JPWO2016152928A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

Provided are a liquid crystal aligning agent, a liquid crystal aligning film and a liquid crystal display element for obtaining a liquid crystal aligning film for a photo-alignment method which does not generate a bright spot even when a negative type liquid crystal is used and can obtain good afterimage characteristics. A liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor having a structure represented by formula (1) in the main chain and an imidized polymer of the polyimide precursor. [Chemical Formula 1] (R1 and R2 are a single bond, -O-, -S-, -NR12-, etc., R12 is a hydrogen atom, etc., A is an alkylene group having 2 to 20 carbon atoms, B1 and B2 are each independently a divalent organic group selected from the following structures, and B1 and B2 are not the same.] [Chemical Formula 2] (R4 represents an alkylene group having 1 to 5 carbon atoms. , R5 represents a hydrogen atom or the like.)

Description

  The present invention relates to a liquid crystal alignment agent used for manufacturing a liquid crystal display element having good afterimage characteristics, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film.

The photo-alignment method is an industrially simple manufacturing process as a rubbing-less alignment treatment method. In particular, in the liquid crystal display element of the IPS (In-Plane-Switching) driving method and the FFS (Flinge-field-Switching) driving method, the rubbing treatment method is used by using the liquid crystal alignment film obtained by the above-described photo-alignment method. Compared with the obtained liquid crystal alignment film, the contrast and viewing angle characteristics of the liquid crystal display element can be expected to be improved. As a result, the performance of the liquid crystal display element can be improved, and has attracted attention as a promising liquid crystal alignment method.
However, the liquid crystal alignment film obtained by the photo-alignment method has a problem that anisotropy with respect to the alignment direction of the polymer film is smaller than that by rubbing. If the anisotropy is small, sufficient liquid crystal orientation cannot be obtained, and problems such as occurrence of an afterimage occur when a liquid crystal display element is formed.
On the other hand, as a method for increasing the anisotropy of the liquid crystal alignment film obtained by the photo-alignment method, it has been proposed to remove the low molecular weight component generated by cutting the main chain of the polyimide by light irradiation after the light irradiation. .

Japanese Unexamined Patent Publication No. 9-297313 Japanese Unexamined Patent Publication No. 2011-107266

“Liquid crystal alignment film”, Kidowaki, Ichimura Functional Materials Vol.17 (1997) No. 11 p.13-22

Conventionally, a positive type liquid crystal is used for an IPS driving type or FFS driving type liquid crystal display element. By using a negative type liquid crystal, it is possible to reduce the transmission loss at the upper part of the electrode and improve the contrast. Is possible.
When a liquid crystal alignment film obtained by a photo-alignment method is used for an IPS driving type or FFS driving type liquid crystal display element using negative liquid crystal, it is expected to have higher display performance than a conventional liquid crystal display element. However, as a result of examination by the present inventors, when a liquid crystal display element is produced using a so-called photodecomposition type liquid crystal alignment film and negative liquid crystal in which anisotropy is produced by polymer decomposition by light irradiation and liquid crystal is aligned. It was found that the incidence of display defects (bright spots) derived from the decomposition products of the polymer constituting the liquid crystal alignment film produced by irradiation with polarized ultraviolet rays was high.
An object of the present invention is to provide a liquid crystal aligning agent for obtaining a liquid crystal aligning film for a photo-alignment method in which no bright spots are generated and good afterimage characteristics are obtained even when a negative type liquid crystal is used. An object of the present invention is to provide a liquid crystal alignment film obtained and a liquid crystal display device including the liquid crystal alignment film.

（式中、Ｒ_１及びＲ_２は、それぞれ独立して、単結合、−Ｏ−、−Ｓ−、−ＮＲ_１２−、エステル結合、アミド結合、チオエステル結合、ウレア結合、カーボネート結合、又はカルバメート結合であり、Ｒ_１２は、水素原子、又はメチル基である。Ａは炭素数２〜２０のアルキレン基である。Ｂ_１及びＢ_２は、それぞれ独立して、下記構造から選ばれる２価の有機基であり、Ｂ_１とＢ_２は同じ構造ではない。）

（式中、Ｒ_４は、炭素数１〜５のアルキレン基である。Ｒ_５は水素原子、メチル基、ヒドロキシ基又はメトキシ基である。）As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, the present invention is as follows.
1. A liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor having a structure represented by the following formula (1) in the main chain and an imidized polymer of the polyimide precursor.

Wherein R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond. R ₁₂ is a hydrogen atom or a methyl group, A is an alkylene group having 2 to 20 carbon atoms, and B ₁ and B ₂ are each independently a divalent organic compound selected from the following structures: And B ₁ and B ₂ are not the same structure.)

(In the formula, R ₄ is an alkylene group having 1 to 5 carbon atoms. R ₅ is a hydrogen atom, a methyl group, a hydroxy group, or a methoxy group.)

（式中、Ｘ_１は、下記式（Ｘ１−１）及び（Ｘ１−２）で表される構造からなる群から選ばれる少なくとも１種である。Ｙ_１は前記式（１）で表される２価の有機基である。Ｒ_３は水素原子又は炭素数１〜５のアルキル基である。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。）

2. The liquid crystal aligning agent of said 1 whose said polyimide precursor is a polymer containing the structural unit of following formula (2).

(Wherein, _{X 1} is represented by the following formula (X1-1) and (at least one selected from the group consisting of structures represented by Xl-2) .Y ₁ is the formula (1) A divalent organic group, R ₃ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Z ₁ and Z ₂ may each independently have a hydrogen atom or a substituent; A C1-C10 alkyl group, a C2-C10 alkenyl group, or a C2-C10 alkynyl group.)

５．前記式（１）の構造が下記構造である、上記１〜４のいずれかに記載の液晶配向剤。

（式中、Ａ、Ｒ_１及びＲ_２は、前記と同定義である。）3. The liquid crystal aligning agent of said 2 with which the said polyimide precursor has 20-100 mol% of structural units represented by the said Formula (2) with respect to all the structural units.
4). X ₁ is a liquid crystal aligning agent for optical alignment described in 2 or 3 is a formula (Xl-2).

5. The liquid crystal aligning agent in any one of said 1-4 whose structure of the said Formula (1) is the following structure.

(In the formula, A, R ₁ and R ₂ are as defined above.)

（式中、Ｒ_１及びＲ_２は、それぞれ独立して、単結合、−Ｏ−、−Ｓ−、−ＮＲ_１２−、エステル結合、アミド結合、チオエステル結合、ウレア結合、カーボネート結合、又はカルバメート結合であり、Ｒ_１２は、水素原子又はメチル基であり、Ａは炭素数２〜２０のアルキレン基である。）6). 6. A liquid crystal alignment film obtained by irradiating polarized ultraviolet rays on a film obtained by applying and baking the liquid crystal aligning agent according to any one of 1 to 5 above.
7). 7. A liquid crystal display device comprising the liquid crystal alignment film as described in 6 above.
8). Diamine represented by the following formula.

Wherein R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond. R ₁₂ is a hydrogen atom or a methyl group, and A is an alkylene group having 2 to 20 carbon atoms.)

By using the liquid crystal aligning agent of the present invention, it is possible to suppress a bright spot due to a decomposition product derived from the liquid crystal aligning film generated during the photo-alignment treatment, and to obtain a liquid crystal aligning film having high irradiation sensitivity and excellent liquid crystal aligning properties. In addition, it is possible to provide a highly reliable liquid crystal display element free from display defects.
Although it is not necessarily clear whether the above-mentioned effect can be obtained by using the liquid crystal aligning agent of the present invention, the diamine used as a raw material of the polymer constituting the liquid crystal aligning agent has a specific asymmetric structure. It is presumed that the solubility and crystallinity of the decomposition product generated by light irradiation changed.

上記式（１）において、Ｒ_１及びＲ_２は、それぞれ独立して、単結合、−Ｏ−、−Ｓ−、−ＮＲ_１２−、エステル結合、アミド結合、チオエステル結合、ウレア結合、カーボネート結合、又はカルバメート結合であり、Ｒ_１２は、水素原子又はメチル基である。Ａは炭素数２〜２０のアルキレン基である。Ｂ_１及びＢ_２は、それぞれ独立して、下記構造から選ばれる２価の有機基であり、Ｂ_１とＢ_２は同じ構造ではない。なお、Ｂ_１及びＢ_２は、同じ構造にならないことにより、光照射により生じる分解物の溶解性及び結晶性が変化し、ポリマーの分解成分由来の輝点を抑制することができる。<Specific structure>
The main chain of the polymer constituting the liquid crystal aligning agent of the present invention contains a specific structure represented by the above formula (1) (hereinafter also referred to as a specific structure).

In the above formula (1), R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, Or it is a carbamate bond and R < ₁₂ > is a hydrogen atom or a methyl group. A is an alkylene group having 2 to 20 carbon atoms. B ₁ and B ₂ are each independently a divalent organic group selected from the following structures, and B ₁ and B ₂ are not the same structure. Since B ₁ and B ₂ do not have the same structure, the solubility and crystallinity of the decomposition product generated by light irradiation change, and the bright spots derived from the decomposition components of the polymer can be suppressed.

上記式中、Ｒ_４は、炭素数１〜５のアルキレン基である。Ｒ_５は水素原子、メチル基、ヒドロキシ基又はメトキシ基である。）

In the above formula, R ₄ is an alkylene group having 1 to 5 carbon atoms. R ₅ is a hydrogen atom, a methyl group, a hydroxy group or a methoxy group. )

In the above formula (1), among these, R ₁ and R ₂ are preferably a single bond, —O—, —S—, —NR ₁₂ —, an ester bond or an amide bond from the viewpoint of liquid crystal alignment. -O- is particularly preferred. A is preferably an alkylene group having 2 to 6 carbon chains, and particularly preferably an alkylene group having 2 to 4 carbon chains, from the viewpoint of liquid crystal alignment.
In the above formula, R ₄ is preferably an alkylene group having 1 to 3 carbon atoms from the viewpoint of liquid crystal alignment. R ₅ is preferably a hydrogen atom or a methyl group from the viewpoint of liquid crystal orientation.
The specific structure described above is preferably contained in a diamine which is a raw material for the polyimide precursor. Specific examples of the diamine having the specific structure described above include, but are not limited to, the following diamines.

（Ｒ_５は、前記と同定義である。）

(R ₅ has the same definition as above.)

上記式において、Ｒ_５及びＲ_１２は、それぞれの好ましい例も含めて、前記と同定義である。

In the above formula, R ₅ and R ₁₂ are as defined above, including preferred examples thereof.

上記式中、Ｒ_１、Ｒ_２、Ａは、それぞれの好ましい例を含めて、上記したとおりである。上記特定構造を有するジアミンとしては、なかでも、以下のジアミンが好ましい。

Among them, the diamine having the above specific structure is preferably a diamine having the following structure from the viewpoints of orientation and reduction of bright spots when formed into a liquid crystal display element.

In the above formula, R ₁ , R ₂ and A are as described above including preferred examples thereof. Among the diamines having the specific structure, the following diamines are preferable.

<Synthesis of diamine>
The main synthesis method of the diamine will be described in detail below. In addition, the method demonstrated below is an example, and is not limited to this.
The diamine of the present invention can be obtained by reducing a dinitro compound and converting a nitro group to an amino group as shown in the following reaction formula. In addition, the following reaction formula has described the diamine described in the Example as an example.

  The method for reducing the dinitro compound is not particularly limited, and palladium-carbon, platinum oxide, Raney nickel, platinum black, rhodium-alumina, platinum sulfide carbon, etc. are used as a catalyst. Examples of the method include reduction with hydrogen gas, hydrazine, hydrogen chloride and the like in a solvent. If necessary, an autoclave or the like may be used under pressure. On the other hand, when an unsaturated bond site is included in the structure of the substituent that replaces the hydrogen atom of the benzene ring or saturated hydrocarbon portion, using palladium carbon or platinum carbon, the unsaturated bond site is reduced, There is a risk of becoming a saturated bond. Therefore, reducing conditions using transition metals such as reduced iron, tin, and tin chloride as a catalyst are preferable.

In the synthesis of the dinitro compound, as shown in the following reaction formula, the dinitro compound can be obtained by reacting a commercially available biphenyl derivative with nitrobenzene substituted with a leaving group X such as halogen. Preferred leaving groups X include fluorine atom, chlorine atom, bromine atom, iodine atom, tosylate (-OTs), mesylate (-OMs) and the like.

  The above reaction can be carried out in the presence of a base. The base to be used is not particularly limited as long as it can be synthesized. Inorganic bases such as potassium carbonate, sodium carbonate, cesium carbonate, sodium alkoxide, potassium alkoxide, sodium hydroxide, potassium hydroxide, sodium hydride, pyridine, dimethylamino Examples thereof include organic bases such as pyridine, trimethylamine, triethylamine, and tributylamine. In some cases, when a palladium catalyst such as dibenzylideneacetone palladium or diphenylphosphinoferrocene palladium or a copper catalyst is used in combination, the yield can be improved. From the viewpoint of ease of synthesis, a method using potassium carbonate is preferred, but synthesis is not particularly limited because synthesis is possible by methods other than this method.

<Polymer>
The polyimide precursor which comprises the liquid crystal aligning agent of this invention contains the structural unit of following formula (2).

X ₁ is at least one selected from the group consisting of structures represented by the following formulas (X1-1) and (X1-2). Among these, from the viewpoint of liquid crystal alignment, the following formula (X1-2) is preferable.

Y ₁ is a divalent organic group represented by the formula (1).
R ₃ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Specific examples include methyl group, ethyl group, propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-pentyl group and the like. From the viewpoint of ease of imidization by heating, R ₃ is preferably a hydrogen atom or a methyl group.

Z ₁ and Z ₂ are each independently a hydrogen atom or an optionally substituted 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. It is a group. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a decyl group, a cyclopentyl group, a cyclohexyl group, and a bicyclohexyl group. Examples of the alkenyl group include those obtained by replacing one or more CH ₂ —CH ₂ structures present in the above alkyl group with a CH═CH structure. Specifically, vinyl group, allyl group, 1-propenyl group, isopropenyl group, 2-butenyl group, 1,3-butadienyl group, 2-pentenyl group, 2-hexenyl group, cyclopropenyl group, cyclopentenyl group, A cyclohexenyl group etc. are mentioned. Alkynyl groups include those in which one or more CH ₂ —CH ₂ structures present in the alkyl group are replaced with C≡C structures. Specific examples include an ethynyl group, a 1-propynyl group, and a 2-propynyl group.

The above alkyl group, alkenyl group, and alkynyl group may have a substituent and, depending on the substituent, may form a ring structure. Note that forming a ring structure with a substituent means that the substituents or a substituent and a part of the mother skeleton are bonded to form a ring structure.
Examples of substituents include halogen groups, hydroxyl groups, thiol groups, nitro groups, aryl groups, organooxy groups, organothio groups, organosilyl groups, acyl groups, ester groups, thioester groups, phosphate ester groups, amide groups, alkyls. Group, alkenyl group, alkynyl group and the like.
Examples of the halogen group include a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.
A phenyl group is mentioned as an aryl group. This aryl group may be further substituted with the other substituent described above.

As an organooxy group, the structure represented by OR can be shown. The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above. Specific examples include methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and the like.
As an organothio group, the structure represented by -S-R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, and the like. These Rs may be further substituted with the substituent described above. Specific examples include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group.

As an organosilyl group, the structure represented by -Si- (R) ₃ can be shown. The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above. Specific examples include trimethylsilyl group, triethylsilyl group, tripropylsilyl group, tributylsilyl group, tripentylsilyl group, trihexylsilyl group, pentyldimethylsilyl group, hexyldimethylsilyl group and the like.
As an acyl group, the structure represented by -C (O) -R can be shown. Examples of R include the above-described alkyl group, alkenyl group, and aryl group. These Rs may be further substituted with the substituent described above. Specific examples include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoyl group and the like.

As an ester group, the structure represented by -C (O) O-R or -OC (O) -R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, and the like. These Rs may be further substituted with the substituent described above.
As a thioester group, the structure represented by -C (S) OR or -OC (S) -R can be shown. Examples of R include the aforementioned alkyl group, alkenyl group, alkynyl group, aryl group, and the like. These Rs may be further substituted with the substituent described above.
As a phosphate group, the structure represented by -OP (O)-(OR) ₂ can be shown. The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above.

The amide group is represented by —C (O) NH ₂ , or —C (O) NHR, —NHC (O) R, —C (O) N (R) ₂ , or —NRC (O) R. The structure can be shown. The R may be the same or different, and examples thereof include the alkyl group, alkenyl group, alkynyl group, and aryl group described above. These Rs may be further substituted with the substituent described above.
Examples of the aryl group include the same aryl groups as described above. This aryl group may be further substituted with the other substituent described above.
As an alkyl group, 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, 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.
Examples of the alkynyl group include the same alkynyl groups described above. This alkynyl group may be further substituted with the other substituent described above.

In general, when a bulky structure is introduced, there is a possibility that the reactivity of the amino group and the liquid crystal alignment may be lowered. Therefore, as Z ₁ and Z ₂ , a hydrogen atom or a carbon atom that may have a substituent is 1 The alkyl group of ˜5 is more preferable, and a hydrogen atom, a methyl group or an ethyl group is particularly preferable.
It is preferable to have 20-100 mol% of the structural unit represented by the above formula (2) with respect to all the structural units, and from the viewpoint of liquid crystal orientation, 30-100 mol% is particularly preferable.

Ｒ_３、Ｚ_１及びＺ_２の定義は、上記式（２）と同様である。<Other structural units>
When the polymer which comprises the liquid crystal aligning agent of this invention contains structural units other than the structural unit of the said Formula (2), the structural unit is represented by following formula (3).

The definitions of R ₃ , Z ₁ and Z ₂ are the same as in the above formula (2).

X ₂ is a tetravalent organic group, and Y ₂ is a divalent organic group.
X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. In the polyimide precursor, X ₂ is 2 or more may be mixed. If Specific examples of X _2, include structures of the following formulas (X-1) ~ (X -44).

R _{8 to} R ₁₁ in the formula (X-1) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkyl group having 2 to 6 carbon atoms. An alkynyl group or a phenyl group. When R _{8 to} R ₁₁ have a bulky structure, the liquid crystal alignment may be lowered, and therefore a hydrogen atom, a methyl group, or an ethyl group is more preferable, and a hydrogen atom or a methyl group is particularly preferable.

In Formula (3), Y ₂ is a divalent organic group derived from diamine, and its structure is not particularly limited. If it shows a specific example of the structure of Y _2, include the following (Y-1) ~ (Y -118).

(In formula (Y-109), m and n are each independently an integer of 1 to 11, m + n is an integer of 2 to 12, and in formula (Y-114), h is 1 to 3). (In the formulas (Y-111) and (Y-117), j is an integer of 0 to 3).)
The polyimide precursor used in the present invention is obtained from a reaction between a diamine component and a tetracarboxylic acid derivative, and examples thereof include polyamic acid and polyamic acid ester.

<Polyimide precursor (polyamic acid)>
The polyamic acid which is a polyimide precursor used in the present invention is produced by the following method.
Specifically, tetracarboxylic dianhydride and diamine are reacted in the presence of an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 12 hours. Can be synthesized.

The reaction of the diamine component and the tetracarboxylic acid component is usually performed in an organic solvent. The organic solvent used at that time is not particularly limited as long as the produced polyimide precursor is dissolved. Although the specific example of the organic solvent used for reaction below is given, it is not limited to these examples. Examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl-imidazolidinone. It is done.
When the solubility of the polyimide precursor is high, it is represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formula [D-1] to formula [D-3]. An organic solvent can be used.

式［Ｄ−１］中、Ｄ^１は炭素数１〜３のアルキル基を示し、式［Ｄ−２］中、Ｄ^２は炭素数１〜３のアルキル基を示し、式［Ｄ−３］中、Ｄ^３は炭素数１〜４のアルキル基を示す。

In the formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms. In the formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms. The formula [D-3] Among them, D ³ represents an alkyl group having 1 to 4 carbon atoms.

These solvents may be used alone or in combination. Furthermore, even if it is a solvent which does not dissolve a polyimide precursor, you may mix and use it for the said solvent in the range which the produced | generated polyimide precursor does not precipitate. Moreover, since water in the solvent inhibits the polymerization reaction and further causes hydrolysis of the produced polyimide precursor, it is preferable to use a dehydrated and dried solvent.
The concentration of the polyamic acid polymer in the reaction system 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 body is easily obtained.

  The polyamic acid obtained as described above can be recovered by precipitating the polymer by pouring into the poor solvent while thoroughly stirring the reaction solution. In addition, by performing precipitation several times, washing with a poor solvent, and then drying at normal temperature or heat, a purified polyamic acid powder can be obtained. Although a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.

<Polyimide precursor (polyamic acid ester)>
The polyamic acid ester which is a polyimide precursor used in the present invention can be produced by the following production method (1), (2) or (3).

(1) When manufacturing from polyamic acid A polyamic acid ester can be manufactured by esterifying the polyamic acid manufactured as mentioned above. Specifically, it is produced by reacting a polyamic acid and an esterifying agent in the presence of an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 4 hours. be able to.

  As the esterifying agent, those that can be easily removed by purification are preferred, 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 per 1 mol of the polyamic acid repeating unit.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl- Examples include imidazolidinone. When the solvent solubility of the polyimide precursor is high, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the above formula [D-1] to formula [D-3] The indicated solvents 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, you may mix and use it for the said solvent in the range which the produced | generated polyimide precursor does not precipitate. Further, since water in the solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyimide precursor, it is preferable to use a dehydrated and dried solvent.

  The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone from the solubility of the polymer. These may be used alone or in combination. Also good. The 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 polymer precipitation is unlikely to occur and a high molecular weight body is easily obtained.

(2) When manufactured by reaction of tetracarboxylic acid diester dichloride and diamine The polyamic acid ester can be manufactured from tetracarboxylic acid diester dichloride and diamine.
Specifically, tetracarboxylic acid diester dichloride and diamine are -20 to 150 ° C, preferably 0 to 50 ° C, in the presence of a base and an organic solvent, for 30 minutes to 24 hours, preferably 1 to 4 hours. It can be produced by reacting.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently. The amount of the base added is preferably 2 to 4 moles relative to the tetracarboxylic acid diester dichloride from the viewpoint that it can be easily removed and a high molecular weight product can be easily obtained.
The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone from the solubility of the monomer and polymer, and these may be used alone or in combination. The polymer concentration during production 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 body is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the production of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.

(3) When manufacturing from tetracarboxylic-acid diester and diamine Polyamic acid ester can be manufactured by polycondensing tetracarboxylic-acid diester and diamine.
Specifically, tetracarboxylic acid diester and diamine are added in the presence of a condensing agent, a base, and an organic solvent at 0 to 150 ° C., preferably at 0 to 100 ° C., for 30 minutes to 24 hours, preferably 3 to 3 hours. It can be produced by reacting for 15 hours.

  Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazi Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N , N ′, N′-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate, and the like. As for the addition amount of a condensing agent, 2-3 times mole is preferable 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 times the molar amount of the diamine component from the viewpoint of easy removal and high molecular weight.
In the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. 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 mole of the diamine component.

Among the methods for producing the three polyamic acid esters, since the high molecular weight polyamic acid ester is obtained, the production method (1) or (2) is particularly preferable.
The polyamic acid ester solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyamic acid ester powder. Although a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.

<Polyimide>
The polyimide used in the present invention can be produced by imidizing the aforementioned polyamic acid ester or polyamic acid.
When a polyimide is produced from a polyamic acid ester, chemical imidization in which a basic catalyst is added to a polyamic acid solution obtained by dissolving a polyamic acid ester solution or a polyamic acid ester resin powder in an organic solvent is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer does not easily decrease during the imidization process.

Chemical imidation can be performed by stirring the polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst. As an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, triethylamine is preferred because it has sufficient basicity to allow the reaction to proceed.
The temperature at which the imidation reaction is performed is -20 to 140 ° C, preferably 0 to 100 ° C, and the reaction time can be preferably 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times that of the amic acid ester group. The imidation rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, reaction time and the like. Since the added catalyst or the like remains in the solution after the imidation reaction, the obtained imidized polymer is recovered by the means described below, redissolved in an organic solvent, and the liquid crystal alignment according to the present invention. It is preferable to use an agent.

When manufacturing a polyimide from a polyamic acid, the chemical imidation which adds a catalyst to the solution of the polyamic acid obtained by reaction with a diamine component and tetracarboxylic dianhydride is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the imidization process.
Chemical imidation can be performed by stirring the polyamic acid to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Of these, acetic anhydride is preferable because purification after completion of the reaction is easy.

  The temperature at which the imidization reaction is performed is -20 to 140 ° C, preferably 0 to 100 ° C, and the reaction time can be preferably 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times of the amic acid group, and the amount of the acid anhydride is 1 to 50 mol times of the amic acid group, preferably 3 to 3 times. 30 mole times. The imidation rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, reaction time and the like.

In the solution after the imidation reaction of polyamic acid ester or polyamic acid, the added catalyst and the like remain, so the obtained imidized polymer is recovered by the means described below, and redissolved in an organic solvent. Thus, the liquid crystal aligning agent of the present invention is preferable.
The polyimide solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyimide powder.
Although it does not specifically limit as a poor solvent, Methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene etc. are mentioned.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention contains at least one polymer selected from the group consisting of a polyimide precursor having a specific structure in the main chain and an imidized polymer of the polyimide precursor. The molecular weight of the polymer is preferably 2,000 to 500,000 in terms of weight average molecular weight (Mw), more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000. The number average molecular weight (Mn) is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000. .

  The concentration of the polymer in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the setting of the thickness of the coating film to be formed, but from the point of forming a uniform and defect-free coating film, 1 The content is preferably at least 10% by mass, and is preferably 10% by mass or less from the viewpoint of storage stability of the solution. The concentration of the polymer is preferably 2 to 7% by mass.

The organic solvent for dissolving the polymer (hereinafter also referred to as a good solvent) contained in the liquid crystal aligning agent used in the present invention is not particularly limited as long as the polymer is uniformly dissolved.
For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone , Cyclohexanone, cyclopentanone or 4-hydroxy-4-methyl-2-pentanone. Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferably used.
Furthermore, when the solubility of the polymer of the present invention in a solvent is high, it is preferable to use a solvent represented by the formula [D-1] to the formula [D-3].
It is preferable that content of the good solvent in the liquid crystal aligning agent of this invention is 20-99 mass% of the whole solvent contained in a liquid crystal aligning agent. Especially, 20-90 mass% is preferable. More preferably, it is 30-80 mass%.

As long as the effects of the present invention are not impaired, the liquid crystal aligning agent of the present invention uses a solvent (also referred to as a poor solvent) that improves the coating properties and surface smoothness of the liquid crystal aligning film when the liquid crystal aligning agent is applied. it can. Although the specific example of a poor solvent is given, it is not limited to these examples.
For example, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2- Etanji 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentane Diol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2 Heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1- (Butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, Dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate Tar, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol Monoethyl ether, milk Methyl, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, 3-methoxypropion Ethyl acid, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, lactic acid Examples thereof include isoamyl esters and solvents represented by the formula [D-1] to the formula [D-3].

Of these, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether or dipropylene glycol dimethyl ether are preferable.
The content of these poor solvents is preferably 1 to 80% by mass of the whole solvent contained in the liquid crystal aligning agent. Especially, 10-80 mass% is preferable and 20-70 mass% is more preferable.

  In the liquid crystal aligning agent of the present invention, in addition to the above, as long as the effects of the present invention are not impaired, a polymer other than the polymer described in the present invention, the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film, etc. Dielectric or conductive material for changing characteristics, silane coupling agent for improving adhesion between liquid crystal alignment film and substrate, crosslinkability for increasing hardness and density of liquid crystal alignment film When baking a compound and also a coating film, you may add the imidation promoter for the purpose of making the imidation by the heating of a polyimide precursor progress efficiently.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention is a film obtained by applying the liquid crystal aligning agent to a substrate, drying and baking. 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 a glass substrate, a silicon nitride substrate, an acrylic substrate, a plastic substrate such as a polycarbonate substrate, or the like can be used. It is preferable to use a substrate on which an ITO electrode or the like for driving is formed in terms of simplification of the process. In the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light such as aluminum can be used as the electrode.

Examples of the method for applying the liquid crystal aligning agent of the present invention include a spin coating method, a printing method, and an ink jet method.
Arbitrary temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent. Usually, in order to sufficiently remove the contained organic solvent, the drying temperature is preferably 50 to 120 ° C., and the drying time is preferably 1 to 10 minutes. The firing temperature is preferably 150 to 300 ° C., and the firing time is preferably 5 to 120 minutes.
The thickness of the film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be impaired, so it is preferably 5 to 300 nm, more preferably 10 to 120 nm.

As a method of photo-alignment treatment of the liquid crystal alignment film, the coating film surface is irradiated with radiation deflected in a certain direction, and in some cases, heat treatment is further performed at a temperature of 150 to 250 ° C. to impart liquid crystal alignment ability. A method is mentioned. As the radiation, ultraviolet rays and visible rays 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.
Since higher anisotropy can be imparted, the higher the extinction ratio of polarized ultraviolet light, the better. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10: 1 or more, and more preferably 20: 1 or more.

The film irradiated with polarized radiation may then be contact-treated with a solvent containing at least one selected from water and an organic solvent.
The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves a decomposition product generated by light irradiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, 3- Examples include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate and the like. Two or more of these solvents may be used in combination. In view of versatility and safety, at least one selected from the group consisting of water, 2-propanol, 1-methoxy-2-propanol and ethyl lactate is more preferable. Water, 2-propanol, or a mixed solvent of water and 2-propanol is particularly preferable.

In the present invention, examples of the contact treatment between the film irradiated with polarized radiation and the solution containing the organic solvent include immersion treatment, spraying treatment, and the like, such that the membrane and the liquid are sufficiently in contact with each other. Is preferred. Especially, the method of immersing a film | membrane in the solution containing an organic solvent for 10 seconds to 1 hour, more preferably 1 to 30 minutes is preferable. The contact treatment may be heated at normal temperature, but is preferably performed at 10 to 80 ° C, more preferably at 20 to 50 ° C. Moreover, a means for enhancing contact such as ultrasonic waves can be applied as necessary.
After the contact treatment, for the purpose of removing the organic solvent in the used solution, rinsing (rinsing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, drying, or both are performed. You may go.

Furthermore, the film subjected to the contact treatment with the solvent may be heated at 150 ° C. or higher for the purpose of drying the solvent and reorienting the molecular chains in the film. As heating temperature, 150-300 degreeC is preferable. A higher temperature promotes reorientation of molecular chains. However, if the temperature is too high, molecular chains may be decomposed. Therefore, the heating temperature is more preferably 180 to 250 ° C, and particularly preferably 200 to 230 ° C.
If the heating time is too short, the effect of reorientation of the molecular chain may not be obtained, and if it is too long, the molecular chain may be decomposed, so 10 seconds to 30 minutes are preferable. 10 minutes is more preferable.

<Liquid crystal display element>
The liquid crystal display device of the present invention is a device in which a liquid crystal cell is prepared by a known method after obtaining a substrate having a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention, and the cell is used as an element. is there.
As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described below as an example. Note that an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may be used.

First, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes may be ITO electrodes, for example, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ —TiO ₂ formed by a sol-gel method.
Next, the liquid crystal alignment film of the present invention is formed on each substrate. Next, the other substrate is superposed on one substrate so that the alignment film surfaces face each other, and the periphery is bonded with a sealant. In order to control the substrate gap, it is usually preferable to mix a spacer in the sealing material. In addition, it is preferable that spacers for controlling the substrate gap are also sprayed on the in-plane portion where no sealing material is provided. Also, a part of the sealing material is usually provided with an opening that can be filled with liquid crystal from the outside.

Next, a liquid crystal material is injected into a space surrounded by two substrates and the sealing material through an opening provided in the sealing material. Thereafter, the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method utilizing capillary action in the atmosphere may be used. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surfaces of the two substrates opposite to the liquid crystal layer. By passing through the above process, the liquid crystal display element of this invention is obtained.
In the present invention, as the sealing agent, for example, a resin that is cured by ultraviolet irradiation or heating having a reactive group such as an epoxy group, an acryloyl group, a methacryloyl group, a hydroxy group, an allyl group, or an acetyl group is used. In particular, it is preferable to use a cured resin system having reactive groups of both an epoxy group and a (meth) acryloyl group.

  In order to improve adhesiveness, moisture resistance, etc., you may mix | blend an inorganic filler with said sealing agent. The inorganic filler that can be used is not particularly limited, and specifically, spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, sulfuric acid. Barium, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, Examples include asbestos. Preferably, spherical silica, fused silica, crystalline silica, titanium oxide, titanium black, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, aluminum silicate Etc. Two or more of the above inorganic fillers may be mixed and used.

  The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. The abbreviations of the compounds used are as follows.

NMP: N-methyl-2-pyrrolidone, BCS: Butyl cellosolve

[Synthesis of DA-1 (4 ′-(2- (4-aminophenoxy) ethoxy)-[1,1′-biphenyl] -4-amine)]
First Step: Synthesis of 4-nitro-4 ′-(2- (4-nitrophenoxy) ethoxy) -1,1′-biphenyl (DA-1-1)

4-Hydroxy-4′-nitrobiphenyl (10.0 g, 46.5 mmol) is dissolved in DMF (40.0 g), potassium carbonate (17.2 g, 69.7 mmol) is added, and β-bromo-4-nitro is added. A DMF solution (40.0 g) of phenetole (17.2 g, 69.7 mmol) was added dropwise at 80 ° C.
The mixture was stirred as it was at 80 ° C. for 2 hours, and disappearance of raw materials was confirmed by high performance liquid chromatography (hereinafter abbreviated as HPLC). Thereafter, the reaction solution was allowed to cool to room temperature, water (500.0 g) was added, the precipitate was filtered, and the filtrate was washed twice with water (100.0 g). The obtained filtrate was washed twice with MeOH (500.0 g). The precipitate was filtered and dried under reduced pressure at 50 ° C. to obtain 4-nitro-4 ′-(2- (4-nitrophenoxy) ethoxy) -1,1′-biphenyl (DA-1-1). (White powder, yield: 17.6 g, yield: 99%).

¹ H NMR (DMSO-d ₆ ): δ 8.22-8.29 (m, 4H, C ₆ H ₄ ), 7.94 (d, J = 7.2 Hz, 2H, C ₆ H ₄ ), 7.79 (d, J = 8.8 Hz , 2H, C ₆ H ₄ ), 7.25-7.15 (m, 4H, C ₆ H ₄ ) 4.54-4.45 (m, 4H, CH ₂ ). ¹³ C { ¹ H} NMR (DMSO-d ₆ ): δ 164.1 , 159.6, 146.6, 146.5, 141.4, 130.7, 129.1, 127.5, 126.4, 124.5, 115.7, 115.6, 67.8, 66.7 (each s).
Melting point (DSC): 193 ° C

Second Step: Synthesis of 4 ′-(2- (4-aminophenoxy) ethoxy)-[1,1′-biphenyl] -4-amine (DA-1)

  DA-1-1 (5.0 g, 13.1 mmol) was dissolved in tetrahydrofuran (100.0 g), 5 mass% palladium-carbon (0.1 g) was added, and the mixture was stirred at room temperature for 2 hours in a hydrogen atmosphere. After confirming disappearance of the raw material by HPLC, the reaction solution was dissolved in tetrahydrofuran (800.0 g), the catalyst was removed by filtration, and the filtrate was concentrated. The precipitated solid was stirred and washed in heptane (200.0 g) and filtered. The obtained solid was dried to obtain DA-1 (white powder, yield: 4.0 g, yield: 94%).

¹ H NMR (DMSO-d ₆ ): δ 7.45 (d, J = 8.8 Hz, 2H, C ₆ H ₄ ), 7.29 (d, J = 8.8 Hz, 2H, C ₆ H ₄ ), 6.97 (d, J = 8.8 Hz, 2H, C ₆ H ₄ ), 6.70 (d, J = 8.8 Hz, 2H, C ₆ H ₄ ), 6.62 (d, J = 8.8 Hz, 2H, C ₆ H ₄ ), 6.52 (d, J = 8.8 Hz, 2H, C ₆ H ₄ ), 5.14 (s, 2H, NH ₂ ), 4.64 (s, 2H, NH ₂ ), 4.24 (br, 2H, CH ₂ ), 4.16 (br, 2H, CH ₂ ). ¹³ C { ¹ H} NMR (DMSO-d ₆ ): δ 157.2, 150.0, 148.2, 143.1, 133.9, 127.7, 126.2, 116.3, 115.9, 115.5, 115.0, 114.4, 67.2, 66.9 (each s).
Melting point (DSC): 156 ° C

The hydrogen nuclear magnetic resonance ( ¹ HNMR, 500 MHz) of the synthesis example was measured in a deuterated dimethyl sulfoxide (DMSO-d6) solvent, and the chemical shift was the δ value (ppm) when tetramethylsilane was used as an internal standard. ).

[viscosity]
The viscosity of each solution was measured using an E-type viscometer (TVE-22H, manufactured by Toki Sangyo Co., Ltd.) at a sample amount of 1.1 mL, cone rotor TE-1 (1 ° 34 ′, R24), and a temperature of 25 ° C. .

[Molecular weight]
GPC apparatus: manufactured by Shodex (GPC-101), column: manufactured by Shodex (KD803, series of KD805), column temperature: 50 ° C., eluent: N, N-dimethylformamide (as an additive, lithium bromide-water) Japanese product (LiBr · H ₂ O) is 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L, tetrahydrofuran (THF) is 10 ml / L), flow rate: 1.0 ml / min.
Standard sample for preparing calibration curve: TSK standard polyethylene oxide (weight average molecular weight (Mw); about 900,000, 150,000, 100,000 and 30,000) manufactured by Tosoh Corporation, and polyethylene glycol (peak top) manufactured by Polymer Laboratories Molecular weight (Mp); about 12,000, 4,000 and 1,000).
In order to avoid the overlapping of peaks, the measurement was performed by mixing four types of 900,000, 100,000, 12,000 and 1,000, and three types of 150,000, 30,000 and 4,000. Two samples of the mixed sample were measured separately.

[Production of liquid crystal cell]
A liquid crystal cell having a configuration of a fringe field switching (FFS) mode liquid crystal display element is manufactured.
A glass substrate with an electrode having a size of 30 mm × 50 mm and a thickness of 0.7 mm was prepared. On the substrate, an ITO electrode having a solid pattern constituting a counter electrode as a first layer is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. A comb-like pixel electrode formed by patterning an ITO film as the third layer is disposed on the second SiN film, and the two pixels, the first pixel and the second pixel, are arranged. Forming. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

  The pixel electrode of the third layer has a comb-like shape configured by arranging a plurality of electrode elements having a dogleg shape 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 formed by arranging a plurality of bent-shaped electrode elements in the central portion, the shape of each pixel is not rectangular, but in the central portion like the electrode elements. It has a shape that bends and resembles a bold-faced koji. Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

  When the first region and the second region of each pixel are compared, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film to be described later is used as a reference, in the first region of the pixel, the electrode element of the pixel electrode is formed to form an angle of + 10 ° (clockwise), and in the second region of the pixel The electrode elements of the pixel electrode are formed at an angle of −10 ° (clockwise). That is, in the first region and the second region of each pixel, the direction of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode in the substrate plane is It is comprised so that it may become a mutually reverse direction.

  Next, after filtering the liquid crystal aligning agent through a 1.0 μm filter, the prepared substrate with electrodes, and a glass substrate having a columnar spacer with a height of 4 μm on which an ITO film is formed on the back surface, It applied by spin coat application. After application, the film was dried on an 80 ° C. hot plate for 5 minutes, and then baked in a hot air circulation oven at 230 ° C. for 20 minutes to form a coating film having a thickness of 100 nm. The coated film surface was irradiated with linearly polarized ultraviolet light having a wavelength of 254 nm with an extinction ratio of 10: 1 or more via a polarizing plate. This substrate is immersed in at least one solvent selected from water and an organic solvent for 3 minutes, then immersed in pure water for 1 minute, and then heated on a hot plate at 150 to 300 ° C. for 5 minutes to obtain liquid crystal alignment A substrate with a film was obtained.

  A sealant is printed on one substrate as a set of two substrates, and the other substrate is bonded so that the liquid crystal alignment film surfaces face each other and the orientation direction becomes 0 °. An empty cell was produced by curing. Liquid crystal MLC-7026-100 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS drive liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour and allowed to stand overnight before being used for each evaluation.

[Afterimage evaluation by long-term AC drive]
A liquid crystal cell having the same structure as the liquid crystal cell described above was prepared, and an AC voltage of ± 5 V was applied for 120 hours at a frequency of 60 Hz in a constant temperature environment of 60 ° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left as it was at room temperature for one day.
After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second area of the first pixel became darkest to the angle at which the first area became darkest was calculated as the angle Δ. Also in the second pixel, as in the case of the first pixel, the second area was compared with the first area, and the same angle Δ was calculated.

[Evaluation of bright spot of liquid crystal cell (contrast)]
The bright spot of the liquid crystal cell described above was evaluated. The bright spot of the liquid crystal cell was evaluated by observing the liquid crystal cell with a polarizing microscope (ECLIPSE E600WPOL) (Nikon Corporation). Specifically, the liquid crystal cell was installed with crossed Nicols, and the liquid crystal cell was observed with a polarizing microscope having a magnification of 5 times. The number of confirmed bright spots was counted, and the number of bright spots was less than 10. “Good” and more than “bad”.

<Synthesis Example 1>
In a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 1.44 g (4.50 mmol) of DA-1 and 0.49 g (4.53 mmol) of DA-2 were weighed, and NMP was 25. 38 g was added, and dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 1.92 g (8.56 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and the solid concentration was 12% by mass. Then, 2.82 g of NMP was added and stirred at room temperature for 24 hours to obtain a polyamic acid solution (A). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 1680 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 14700 and Mw = 35000.

<Synthesis Example 2>
In a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 2.24 g (7.00 mmol) of DA-1 was weighed, 24.64 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. . While stirring the diamine solution, 1.49 g (6.65 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and the solid concentration was 12% by mass. Then, 2.73 g of NMP was added and stirred at room temperature for 24 hours to obtain a polyamic acid solution (B). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 2650 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 21300 and Mw = 52300.

<Synthesis Example 3>
In a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 1.51 g (4.71 mmol) of DA-1 and 1.14 g (4.71 mmol) of DA-3 were weighed, and NMP 16. 99 g was added and dissolved by stirring while feeding nitrogen. While stirring the diamine solution, 2.07 g (9.23 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and the solid content concentration was further 20% by mass. Then, 1.89 g of NMP was added and stirred at 40 ° C. for 24 hours to obtain a polyamic acid solution (C). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 5000 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 13900 and Mw = 34100.

<Synthesis Example 4>
In a 50 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 1.59 g (6.51 mmol) of DA-4 and 0.70 g (6.47 mmol) of DA-2 were weighed and 33. 07 g was added and stirred while feeding nitrogen to dissolve. While stirring the diamine solution, 2.71 g (12.09 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and the solid content concentration was 12% by mass. Then, 3.67 g of NMP was added and stirred at room temperature for 24 hours to obtain a polyamic acid solution (D). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 360 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 14500 and Mw = 30200.

<Synthesis Example 5>
In a 50 mL four-necked flask with a stirrer and a nitrogen inlet tube, weigh out 3.59 g (16.01 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 34.18 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this acid dianhydride solution, 1.59 g (14.70 mmol) of DA-2 was added, and 3.80 g of NMP was further added so that the solid content concentration would be 12% by mass. Stirring to obtain a polyamic acid solution (E). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 200 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 12600 and Mw = 30500.

<Example 1>
15.00 g of 12% by mass polyamic acid solution (A) was weighed into a 100 ml Erlenmeyer flask, 9.00 g of NMP and 6.00 g of BCS were added, and mixed at 25 ° C. for 8 hours to obtain a liquid crystal aligning agent (1). . Abnormalities such as turbidity and precipitation were not observed in the liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Example 2>
A liquid crystal aligning agent (2) was obtained in the same manner as in Example 1 except that the polyamic acid solution (B) was used instead of the polyamic acid solution (A). Abnormalities such as turbidity and precipitation were not observed in the liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Example 3>
9.00 g of a 20% by mass polyamic acid solution (C) was placed in a 100 ml Erlenmeyer flask, 15.00 g of NMP and 6.00 g of BCS were added, and the mixture was mixed at 25 ° C. for 8 hours to obtain a liquid crystal aligning agent (3). Abnormalities such as turbidity and precipitation were not observed in the liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Comparative Example 1>
A liquid crystal aligning agent (4) was obtained in the same manner as in Example 1 except that the polyamic acid solution (D) was used instead of the polyamic acid solution (A). Abnormalities such as turbidity and precipitation were not observed in the liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Comparative example 2>
A liquid crystal aligning agent (5) was obtained in the same manner as in Example 1 except that the polyamic acid solution (E) was used instead of the polyamic acid solution (A). Abnormalities such as turbidity and precipitation were not observed in the liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Example 4>
After the liquid crystal aligning agent (1) is filtered through a 1.0 μm filter, spin coating is applied to the substrate with electrodes and a glass substrate having a columnar spacer with a height of 4 μm on which an ITO film is formed on the back surface. Was applied. Next, it was dried on an 80 ° C. hot plate for 5 minutes, and baked in a hot air circulation oven at 230 ° C. for 20 minutes to form a coating film having a thickness of 100 nm. The surface of the coating film was irradiated with 0.2 J / cm ² of linearly polarized ultraviolet light having an extinction ratio of 26: 1 and a wavelength of 254 nm through a polarizing plate. Then, it heated for 14 minutes on a 230 degreeC hotplate, and obtained the board | substrate with a liquid crystal aligning film.

  A pair of two substrates was set, a sealant was printed on one substrate, and the other substrate was bonded so that the liquid crystal alignment film faces each other and the alignment direction was 0 °. Then, the sealing agent was hardened and the empty cell was produced. Liquid crystal MLC-7026-100 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and then the injection port was sealed to obtain an FFS drive liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour and left to stand for evaluation of afterimages by long-term AC driving. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.01 °. Further, as a result of observation of bright spots in the liquid crystal cell, the number of bright spots was less than 10 and was good.

<Example 5>
A coating film was formed in the same manner as in Example 4 except that the liquid crystal aligning agent (2) was used. The surface of the coating film was irradiated with 0.5 J / cm ² of linearly polarized ultraviolet light having an extinction ratio of 26: 1 and a wavelength of 254 nm through a polarizing plate. Then, it heated for 14 minutes on a 230 degreeC hotplate, and obtained the board | substrate with a liquid crystal aligning film. An FFS drive liquid crystal cell was produced in the same manner as in Example 4 except that this substrate with a liquid crystal alignment film was used, and the same evaluation as in Example 4 was performed on the obtained liquid crystal cell. As a result, the value of the angle Δ was 0.03 °. The number of bright spots was less than 10 and was good.

<Example 6>
A coating film was formed in the same manner as in Example 4 except that the liquid crystal aligning agent (3) was used, and irradiated with ultraviolet rays and heated to obtain a substrate with a liquid crystal alignment film. An FFS drive liquid crystal cell was produced in the same manner as in Example 4 except that this substrate with a liquid crystal alignment film was used, and the same evaluation as in Example 4 was performed on the obtained liquid crystal cell. As a result, the value of the angle Δ was 0.02 °. The number of bright spots was less than 10 and was good.

<Comparative Example 3>
Except for using the liquid crystal aligning agent (4), a coating film was formed in the same manner as in Example 4, irradiated with ultraviolet rays, and heated to obtain a substrate with a liquid crystal alignment film. An FFS drive liquid crystal cell was produced in the same manner as in Example 4 except that this substrate with a liquid crystal alignment film was used, and the same evaluation as in Example 4 was performed on the obtained liquid crystal cell. As a result, the value of the angle Δ was 0.10 °. Further, the number of bright spots was 10 or more, which was poor.

<Comparative Example 4>
Except for using the liquid crystal aligning agent (5), a coating film was formed in the same manner as in Example 4, irradiated with ultraviolet rays at 0.5 J / cm ² and heated to obtain a substrate with a liquid crystal aligning film. It was. An FFS drive liquid crystal cell was produced in the same manner as in Example 4 except that this substrate with a liquid crystal alignment film was used, and the same evaluation as in Example 4 was performed on the obtained liquid crystal cell. As a result, the value of the angle Δ was 0.19 °. Further, the number of bright spots was 10 or more, which was poor.

The liquid crystal aligning agent of the present invention is capable of forming a liquid crystal alignment film for a photo-alignment method having a good afterimage characteristic without generating a bright spot even when a negative type liquid crystal is used, and having a high display quality. It can be used for an FFS driving type liquid crystal display element.
The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2015-061095 filed on March 24, 2015 are incorporated herein as the disclosure of the specification of the present invention. Is.

Claims (8)

A liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor having a structure represented by the following formula (1) in the main chain and an imidized polymer of the polyimide precursor.

Wherein R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond. R ₁₂ is a hydrogen atom or a methyl group, A is an alkylene group having 2 to 20 carbon atoms, and B ₁ and B ₂ are each independently a divalent organic group selected from the following structures: And B ₁ and B ₂ are not the same structure.)

(In the formula, R ₄ is an alkylene group having 1 to 5 carbon atoms. R ₅ is a hydrogen atom, a methyl group, a hydroxy group, or a methoxy group.) The liquid crystal aligning agent according to claim 1, wherein the polyimide precursor is a polymer containing a structural unit represented by the following formula (2).

(Wherein, _{X 1} is represented by the following formula (X1-1) and (at least one selected from the group consisting of structures represented by Xl-2) .Y ₁ is the formula (1) A divalent organic group, R ₃ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and Z ₁ and Z ₂ may each independently have a hydrogen atom or a substituent; A C1-C10 alkyl group, a C2-C10 alkenyl group, or a C2-C10 alkynyl group.)

  The liquid crystal aligning agent of Claim 2 in which the said polyimide precursor has 20-100 mol% of structural units represented by the said Formula (2) with respect to all the structural units. X ₁ is, the liquid crystal alignment agent according to claim 2 or 3 is a formula (Xl-2).

The liquid crystal aligning agent of any one of Claims 1-4 whose structure of the said Formula (1) is the following structure.

(In the formula, A, R ₁ and R ₂ are as defined above.)   The liquid crystal aligning film obtained by irradiating the ultraviolet-ray which polarized the film | membrane obtained by apply | coating and baking the liquid crystal aligning agent of any one of Claims 1-5.   A liquid crystal display device comprising the liquid crystal alignment film according to claim 6. Diamine represented by the following formula.

Wherein R ₁ and R ₂ are each independently a single bond, —O—, —S—, —NR ₁₂ —, an ester bond, an amide bond, a thioester bond, a urea bond, a carbonate bond, or a carbamate bond. R ₁₂ is a hydrogen atom or a methyl group, and A is an alkylene group having 2 to 20 carbon atoms.)