WO2017170483A1

WO2017170483A1 - Liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display element

Info

Publication number: WO2017170483A1
Application number: PCT/JP2017/012535
Authority: WO
Inventors: 幸司巴; 泰宏宮本; 玲久小西; 秀則石井; 英之磯貝
Original assignee: 日産化学工業株式会社
Priority date: 2016-03-29
Filing date: 2017-03-28
Publication date: 2017-10-05
Also published as: KR102350408B1; TWI811190B; KR20180128442A; CN109196410B; JP7008946B2; CN109196410A; JPWO2017170483A1; TW201805336A

Abstract

The present invention provides: a liquid crystal aligning agent for obtaining a liquid crystal alignment film that has achieved a good balance between liquid crystal aligning properties and mechanical strength of the film; a liquid crystal alignment film which is obtained using this liquid crystal aligning agent; and a liquid crystal display element which is provided with this liquid crystal alignment film. The present invention provides a liquid crystal aligning agent which contains: a polymer that contains at least one polymer selected from the group consisting of polyimide precursors having a structural unit represented by formula (1) and imidized polymers of the polyimide precursors; a compound represented by formula (3); and an organic solvent. (In formulae (1)-(3), the symbols are as defined in the description.)

Description

Liquid crystal aligning agent, liquid crystal aligning film, and liquid crystal display element

The present invention relates to a liquid crystal aligning agent for producing a liquid crystal aligning film, a liquid crystal aligning film obtained from the liquid crystal aligning agent, and a liquid crystal display element.

The liquid crystal alignment film is a film for controlling the alignment of liquid crystal molecules in a certain direction in a liquid crystal display element or a retardation plate using a polymerizable liquid crystal. For example, a 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. In the liquid crystal display element, the liquid crystal molecules are aligned in a certain direction with a pretilt angle by the liquid crystal alignment film, and respond by applying a voltage to the electrode provided between the substrate and the liquid crystal alignment film. As a result, the liquid crystal display element displays a desired image by utilizing the orientation change due to the response of the liquid crystal molecules. The liquid crystal alignment film is a major constituent member together with liquid crystal molecules and the like in a liquid crystal display element or the like.

There are various properties required for liquid crystal alignment films. High resistance to rubbing is one of the important characteristics. The rubbing process is known as a method of forming a liquid crystal alignment film from a polymer film formed on a substrate in a manufacturing process of a liquid crystal display element, and is still widely used industrially today. In the rubbing process, an alignment process is performed by rubbing the surface of the polymer film such as polyimide formed on the substrate with a cloth.

In such rubbing treatment, there is a known problem that dust generated by scraping the liquid crystal alignment film or scratches on the liquid crystal alignment film deteriorates display quality. For this reason, the liquid crystal alignment film is required to have resistance to rubbing treatment (hereinafter also referred to as rubbing resistance).

As a method for forming a liquid crystal alignment film having high rubbing resistance, a polymer obtained by reacting tetracarboxylic dianhydride and a diamine compound and / or an imidized polymer thereof, and two in a molecule It is disclosed that a liquid crystal alignment film having a constant pretilt angle can be obtained regardless of rubbing conditions by using a liquid crystal aligning agent containing a compound containing the above epoxy group (see Patent Documents 1 and 2). .

JP 7-234410 A Japanese Patent Laid-Open No. 10-338880

In recent years, liquid crystal display elements such as smartphones are rapidly becoming lighter and thinner. Accordingly, in the production of liquid crystal panels, a so-called “sliming process” is often performed in which the glass substrate of the liquid crystal panel after production is polished. In this step, there are a chemical method using hydrofluoric acid and a physical polishing method using an abrasive.
When physically polishing, the produced liquid crystal panel may be bent depending on the apparatus used for polishing, and as a result, stress is applied to the liquid crystal alignment film from all directions. Therefore, when the mechanical strength of the liquid crystal alignment film is weak, the film breaks particularly around the column spacer, which may cause defects. Conventional liquid crystal alignment films having sufficient resistance to rubbing often have insufficient resistance to the slimming process.
In view of the above, a liquid crystal alignment film having further enhanced mechanical strength is demanded.
An object of the present invention is to provide a liquid crystal alignment film having high mechanical strength and a liquid crystal alignment agent for obtaining the same.

The present inventor has intensively studied to achieve the above object, and as a result, a polyimide precursor obtained from an additive having a specific structure and a diamine compound having a specific structure, and an imidized polymer of the polyimide precursor. It has been found that the above object can be achieved by a liquid crystal aligning agent containing at least one polymer selected from the group consisting of:
Thus, the present invention has the following gist.

1. A polymer comprising at least one selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (1) and an imidized polymer of the polyimide precursor, a compound represented by the following formula (3) And a liquid crystal aligning agent containing an organic solvent.

In formula (1), X ¹ is a tetravalent organic group derived from a tetracarboxylic acid derivative,
Y ¹ is a divalent organic group derived from diamine and having the structure of formula (2),
R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
In the formula (2), R ² is a single bond or a divalent organic group, and R ³ is a structure represented by — (CH ₂ ) _n — (where n is an integer of 2 to 20, Arbitrary —CH ₂ — may be replaced with an ether, ester, amide, urea, or carbamate bond under non-adjacent conditions.), R ⁴ is a single bond or a divalent organic group on the benzene ring Any hydrogen atom may be replaced with a monovalent organic group.
In the formula (3), p is an integer of 1 to 6.

Since the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention can achieve both the mechanical strength of the film and the liquid crystal alignment of the film, the film is scraped not only in the rubbing process but also in the slimming process. As a result, a liquid crystal display element having good display characteristics can be obtained.

The liquid crystal aligning agent of the present invention is a polymer containing at least one selected from the group consisting of a polyimide precursor having a structural unit represented by the above formula (1) and an imidized polymer of the polyimide precursor (hereinafter, A liquid crystal aligning agent containing a compound represented by the above formula (3) (hereinafter also referred to as a specific compound) and an organic solvent. Hereinafter, each constituent requirement will be described in detail.

<Specific polymer>
The specific polymer contained in the liquid crystal aligning agent of this invention is a polymer containing the structural unit of following formula (1).

In the formula (1), X ¹ is a tetravalent organic group derived from a tetracarboxylic acid derivative. The specific structure is at least one selected from the group consisting of structures represented by the following formulas (X1-1) to (X1-45).

In the formula (X1-1), R ⁵ , R ⁶ , R ⁷ and R ⁸ 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, An alkynyl group or a phenyl group, which may be the same or different. From the viewpoint of liquid crystal orientation, R ⁵ , R ⁶ , R ⁷ , and R ⁸ are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, more preferably a hydrogen atom or a methyl group, and still more preferably, At least one selected from the group consisting of structures represented by the following formulas (X1-10) to (X1-11).

Among these structures, (X1-10), (X1-11), and (X1-29) are preferable, and (X1-10) and (X1-11) are more preferable from the viewpoint of liquid crystal alignment and reliability. .
In the formula (1), R ₁ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. From the viewpoint of ease of imidization by heating, a hydrogen atom or a methyl group is particularly preferable.
In the polyimide precursor containing the structural unit represented by the formula (1) and the imidized polymer of the polyimide precursor, the structural unit represented by the formula (1) and a structural unit obtained by imidizing the structural unit are selected. The ratio of at least one structural unit is preferably 20 mol% to 100 mol% with respect to 1 mol of all structural units in the polymer. From the viewpoint of achieving both liquid crystal alignment and reliability, 70 mol% is more preferable, and 50 mol% to 70 mol% is more preferable.
Y ¹ is a divalent organic group derived from a diamine and having a structure of the following formula (2).

R ² is a single bond or a divalent organic group, preferably a single bond.
R ³ is a structure represented by — (CH ₂ ) _n —. n is an integer of 2 to 10, preferably 3 to 7. Arbitrary —CH ₂ — may be replaced with an ether, ester, amide, urea, or carbamate bond under the condition that they are not adjacent to each other.
R ⁴ is a single bond or a divalent organic group.
Any hydrogen atom on the benzene ring may be replaced with a monovalent organic group, and a fluorine atom or a methyl group is preferred.
Specific examples include the following structures, but are not limited thereto.

The specific polymer contained in the liquid crystal aligning agent of the present invention may contain a structural unit represented by the following formula (4) in addition to the structural unit represented by the above formula (1).

In formula (4), _{R 1} has the same definition as _{R 1} in the formula (1). X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. Specific examples include the structures of the above formulas (X1-1) to (X-45).
In the above formula (4), Y ₂ is a divalent organic group derived from diamine, and its structure is not particularly limited. Specific examples of Y ₂ include structures of the following formulas (Y-1) to (Y-137).

<Specific compounds>
The specific compound contained in the liquid crystal aligning agent of this invention is represented by following formula (3).

In the formula (3), p is an integer of 1 to 6, preferably 1 to 3, more preferably 1.
Specific examples include the following structures.

The content of the compound represented by the above formula (3) is preferably 1-20 parts by weight, more preferably 1-10 parts by weight.
Moreover, in the range which does not impair the effect of this invention, you may use 2 or more types of compounds of the said Formula (3).

<Method for producing polyamic acid ester>
The polyamic acid ester which is a polyimide precursor used in the present invention can be synthesized by the method (1), (2) or (3) shown below.

(1) When synthesizing from polyamic acid The polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from tetracarboxylic dianhydride and diamine.
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. Can be synthesized.

The esterifying agent is preferably one that can be easily removed by purification, 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.
The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in view of polymer solubility. These may be used alone or in combination of two or more. Good. The concentration at the time of synthesis 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 product is easily obtained.

(2) When synthesized by reaction of tetracarboxylic acid diester dichloride and diamine Polyamic acid ester can be synthesized from tetracarboxylic acid diester dichloride and diamine.
Specifically, tetracarboxylic acid diester dichloride and diamine in the presence of a base and 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 synthesized 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 addition amount of the base is preferably 2 to 4 times the molar amount of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.
The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of the monomer and polymer, and these may be used alone or in combination. The polymer concentration at the time of synthesis is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is difficult to occur and a high molecular weight product is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the synthesis 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 synthesizing polyamic acid ester from tetracarboxylic acid diester and diamine Polyamic acid ester can be synthesized by polycondensation of tetracarboxylic acid diester and diamine.
Specifically, tetracarboxylic acid diester and diamine in the presence of a condensing agent, a base, and an organic solvent at 0 ° C. to 150 ° C., preferably 0 ° C. to 100 ° C., for 30 minutes to 24 hours, preferably 3 to 15 It can synthesize | combine by making it react for time.

Examples of the condensing agent include triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triazide. Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N , N ′, N′-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like. The addition amount of the condensing agent is preferably 2 to 3 times the molar amount of the tetracarboxylic acid diester.
As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is preferably 2 to 4 times mol with respect to 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 mol with respect to the diamine component.
Among the methods for synthesizing the three polyamic acid esters, since a high molecular weight polyamic acid ester is obtained, the synthesis 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, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying. Although a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.

<Method for producing polyamic acid>
The polyamic acid which is a polyimide precursor used in the present invention can be synthesized by the following method.
Specifically, tetracarboxylic dianhydride and diamine 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 12 hours. Can be synthesized.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in view of the solubility of the monomer and polymer. These may be used alone or in combination of two or more. It may be used. 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 difficult 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. Moreover, the powder of polyamic acid refine | purified by performing precipitation several times, washing | cleaning with a poor solvent, and normal temperature or heat-drying can be obtained. Although a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.

<Production method of polyimide>
The polyimide used in the present invention can be produced by imidizing the 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 the polyamic acid ester solution or the 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 during the imidation reaction is −20 ° C. to 140 ° C., preferably 0 ° C. to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, of the amic acid ester group. The imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time. 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, chemical imidation which adds a catalyst to the solution of the said 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 a polymer 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. Among them, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated.

The temperature for carrying out the imidization reaction is −20 ° C. to 140 ° C., preferably 0 ° C. to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times the amic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times the amic acid group. Is double. The imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.
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, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying.
The poor solvent is not particularly limited, and examples thereof include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.

<Liquid crystal aligning agent>
The liquid crystal aligning agent used in the present invention has a form of a solution in which a polymer having a specific structure is dissolved in an organic solvent. The molecular weight of at least one polymer selected from the polyimide precursor having the structural unit represented by the above formula (1) and the imidized polymer of the polyimide precursor is 2,000 to 500,000 in weight average molecular weight. Is more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000.

The liquid crystal aligning agent used in the present invention may contain a polymer other than the polymer described in the present invention. Among them, a specific polymer containing at least one selected from the group consisting of a polyimide having a structural unit represented by the above formula (1) and an imidized polymer of the polyimide precursor, and a polyimide other than the specific polymer It is preferable that a polymer containing at least one selected from the group consisting of a precursor and an imidized polymer of the polyimide precursor is included because the effects of the present invention can be further expressed. Further, the polymer is selected from the group consisting of a polyamic acid other than the specific polymer including at least one selected from the group consisting of a polyimide having a structural unit represented by the above formula (1) and a polyamic acid ester. It is more preferable that a polymer containing at least one kind is included.

The concentration of the polymer of the liquid crystal aligning agent used in the present invention (when a polymer other than the specific polymer is included, it means the total concentration thereof) is the setting of the thickness of the coating film to be formed. However, it is preferably 1% by weight or more from the viewpoint of forming a uniform and defect-free coating film, and preferably 10% by weight or less from the viewpoint of storage stability of the solution. .

<Organic solvent>
The organic solvent contained in the liquid crystal aligning agent used in the present invention is not particularly limited as long as the polymer having a specific structure is uniformly dissolved (hereinafter also referred to as a good solvent). Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, Examples include 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N, N-dimethylpropanamide and the like. You may use these 1 type or in mixture of 2 or more types. Moreover, even if it is a solvent which cannot melt | dissolve a polymer uniformly independently, if it is a range which a polymer does not precipitate, you may mix with said organic solvent. The good solvent in the liquid crystal aligning agent is preferably 20 to 99% by mass of the total solvent, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass.

The liquid crystal aligning agent can contain 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, as long as the effects of the present invention are not impaired. As such a solvent, a solvent having a surface tension lower than that of the organic solvent is generally used. These poor solvents are preferably 1 to 80% by mass of the whole solvent contained in the liquid crystal aligning agent. Of these, 10 to 80% by mass is preferable. More preferred is 20 to 70% by mass.

Although the specific example of a poor solvent is given to the following, 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 acetate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, lactate n-propyl ester, lactate n-butyl ester, lactic acid Examples thereof include isoamyl esters and solvents represented by the following formulas [D-1] to [D-3].
In the formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, and in the formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms, and the formula [D-3] In the formula, D ³ represents an alkyl group having 1 to 4 carbon atoms.

Of these, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or dipropylene glycol dimethyl ether is preferably used.
In addition to the above, the liquid crystal aligning agent of the present invention has a dielectric or conductive material for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film, as long as the effects of the present invention are not impaired. Silane coupling agent for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate, a crosslinkable compound for the purpose of increasing the hardness and density of the liquid crystal alignment film, and polyimide for firing the coating film An imidization accelerator for the purpose of efficiently proceeding imidization by heating the precursor may be added.

<Method for producing liquid crystal alignment film>
The liquid crystal alignment film of the present invention is produced through a step of applying a liquid crystal aligning agent to a substrate and baking, and a step of applying an alignment treatment to the obtained film.
(1) Step of applying liquid crystal aligning agent to substrate and baking The liquid crystal aligning agent obtained as described above is applied to the substrate, dried and fired to form a polyimide film or a polyimide precursor imidized film. Is obtained.
The substrate to which the liquid crystal aligning agent used in 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, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, and the like can be used. The use of a substrate on which an ITO electrode or the like for driving a liquid crystal is formed is preferable from the viewpoint of simplification of the process. Further, in the reflection type liquid crystal display element, an opaque material such as a silicon wafer can be used as long as it is only on one side of the substrate. Examples of the method for applying the liquid crystal aligning agent used in 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 used in the present invention. Usually, in order to sufficiently remove the organic solvent contained, drying is performed at 50 ° C. to 120 ° C. for 1 minute to 10 minutes, and then baking is performed at 150 ° C. to 300 ° C. for 5 minutes to 120 minutes. The thickness of the coating film after baking is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered, and therefore it is 5 to 300 nm, preferably 10 to 200 nm.

(2) Step of applying alignment treatment to the obtained film As alignment treatment, in addition to rubbing treatment performed by a known method, polarized ultraviolet rays are irradiated and liquid crystal alignment is performed on the film by photoreaction of photoreactive groups in the film. The photo-alignment process which provides property is mentioned.
In the case of the photo-alignment treatment, it is manufactured by a method for manufacturing a liquid crystal alignment film, which includes a step of irradiating polarized ultraviolet rays, and a step of cleaning the film irradiated with ultraviolet rays with a cleaning liquid mainly containing water or 2-propanol. Is preferred. Specifically, the process is as follows.

Anisotropy is imparted to the film obtained by the method (1) by irradiating polarized ultraviolet rays (hereinafter also referred to as photo-alignment treatment).
A higher extinction ratio of polarized ultraviolet rays is preferable because higher anisotropy can be imparted. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10: 1 or more, and more preferably 20: 1 or more.
As a specific example of the photo-alignment treatment, there is a method in which the surface of the coating film is irradiated with linearly polarized ultraviolet rays, and in some cases, a heat treatment is further performed at a temperature of 150 to 250 ° C. to impart liquid crystal alignment ability. It is done. As the wavelength of ultraviolet rays, ultraviolet rays having a wavelength of 100 nm to 400 nm are preferable, and those having a wavelength of 200 nm to 400 nm are particularly preferable.
Dose of the radiation is preferably in the range of 1 ~ 10,000mJ / cm ^2, and particularly preferably in the range of 100 ~ 5,000mJ / cm ^2.

(3) Step of cleaning the film irradiated with ultraviolet rays The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention has good characteristics as a liquid crystal alignment film by cleaning with a cleaning liquid mainly composed of water or 2-propanol. It is characterized by expressing. Since 2-propanol dissolves organic substances in the film more easily than water, a cleaning liquid containing 2-propanol is more preferable as the cleaning liquid for the liquid crystal alignment film of the present invention.
As a method for cleaning the liquid crystal alignment film, a treatment such that the film and the liquid are sufficiently in contact with each other, such as an immersion treatment or a spraying treatment, is preferable. Among them, a method of immersing the film in the cleaning solution, preferably 10 seconds to 1 hour, more preferably 1 minute to 30 minutes is preferable. The contact treatment may be performed at normal temperature or preferably at 10 to 80 ° C., more preferably 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 used, either or both of rinsing with water, 2-propanol, acetone and other low boiling solvents, drying, or both may be performed. The drying temperature is preferably 80 to 250 ° C, more preferably 80 to 150 ° C.

<Liquid crystal display element>
The liquid crystal display element of this invention comprises the liquid crystal aligning film obtained by the manufacturing method of the said liquid crystal aligning film.
In the liquid crystal display element of the present invention, after obtaining the substrate with the liquid crystal alignment film by the method for producing the liquid crystal alignment film from the liquid crystal alignment treatment agent described in the present invention by the method described above, a liquid crystal cell is prepared by a known method. In this way, a liquid crystal display element is obtained.
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 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 can 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 embodiment 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, a spacer is usually mixed 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. A part of the sealing material is provided with an opening that can be filled with liquid crystal from the outside.

Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealing material through the 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. Since this liquid crystal display element uses the liquid crystal alignment film of the present invention as the liquid crystal alignment film, the liquid crystal display element has excellent afterimage characteristics and can be suitably used for a large-screen, high-definition liquid crystal television.

Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to these examples. In addition, the symbol of a compound and a solvent is as follows.

NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone BCS: butyl cellosolve PB: propylene glycol monobutyl ether IPA: isopropanol DBOP: diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate DA- 1: The following structural formula (DA-1)
DA-2: Structural formula below (DA-2)
DA-3: Structural formula below (DA-3)
DA-4: Structural formula below (DA-4)
DA-5: Structural formula below (DA-5)
DA-6: Structural formula below (DA-6)
DA-7: Structural formula below (DA-7)
DA-8: Structural formula below (DA-8)
DA-9: Structural formula below (DA-9)
CA-1: Structural formula below (CA-1)
CA-2: Structural formula below (CA-2)
CA-3: Structural formula shown below (CA-3)
CA-4: Structural formula below (CA-4)
CA-5: Structural formula below (CA-5)
CA-6: Structural formula below (CA-6)
AD-1: Structural formula below (AD-1)
AD-2: Structural formula below (AD-2)
AD-3: Structural formula below (AD-3)
AD-4: Structural formula below (AD-4)
AD-5: Structural formula below (AD-5)
AD-6: Structural formula below (AD-6)

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

[Measurement of imidization ratio of polyimide]
The imidation ratio of polyimide in the synthesis example was measured as follows. 30 mg of polyimide powder was put into an NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard, φ5 (manufactured by Kusano Kagaku)), and deuterated dimethyl sulfoxide (DMSO-d6, 0.05 mass% TMS (tetramethylsilane)) (Mixed product) (0.53 ml) was added and completely dissolved by applying ultrasonic waves. This solution was measured for proton NMR at 500 MHz with an NMR measuring instrument (JNW-ECA500) (manufactured by JEOL Datum). The imidation rate is determined based on protons derived from structures that do not change before and after imidation as reference protons, and the peak integrated value of these protons and proton peaks derived from NH groups of amic acid that appear in the vicinity of 9.5 ppm to 10.0 ppm. It calculated | required by the following formula | equation using the integrated value.
Imidization rate (%) = (1−α · x / y) × 100
In the above formula, x is a proton peak integrated value derived from NH group of amic acid, y is a peak integrated value of reference proton, α is one NH group proton of amic acid in the case of polyamic acid (imidation rate is 0%) Is the number ratio of the reference proton to.

(Synthesis Example 1)
In a 200 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 11.2 g (46.0 mmol) of DA-1 was weighed, 129 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution under water cooling, 8.38 g (43.0 mmol) of CA-1 was added, 47.4 g of NMP was further added, and the mixture was stirred at 23 ° C. for 5 hours under a nitrogen atmosphere to obtain a polyamic acid solution ( PAA-1) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 154 mPa · s.

(Synthesis Example 2)
Into a 200 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube, 9.97 g (38.3 mmol) of CA-2 was added, and 197 g of NMP was added and stirred to dissolve. Next, 12.1 g (120 mmol) of triethylamine, 5.06 g (22.0 mmol) of DA-2, 1.79 g (6.00 mmol) of DA-3, and 4.09 g (12.0 mmol) of DA-4 were added. And dissolved by stirring.
While stirring this solution under water cooling, 30.1 g (78.6 mmol) of DBOP was added, 27.1 g of NMP was further added, and the mixture was stirred at room temperature for 12 hours to obtain a polyamic acid ester solution. The viscosity of this polyamic acid ester solution at a temperature of 25 ° C. was 39.3 mPa · s.

This polyamic acid ester solution was put into 1700 g of IPA, and the resulting 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 polyamic acid ester powder.
In a 200 mL Erlenmeyer flask containing a stirrer, 16.0 g of this polyamic acid ester powder was taken, 117 g of NMP was added, and stirred at 50 ° C. for 30 hours to dissolve, so that a polyamic acid ester solution (PAE- 1) was obtained.

(Synthesis Example 3)
In a 500 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 7.32 g (30.0 mmol) of DA-1 and 23.9 g (120 mmol) of DA-5 were added, and 158 g of NMP and GBL were added, and nitrogen was added. Was dissolved by stirring while feeding. While stirring this diamine solution under water cooling, 12.8 g (65.0 mmol) of CA-1 and 40.0 g of NMP and GBL were added, respectively, and the mixture was stirred at 23 ° C. for 3 hours under a nitrogen atmosphere. Further, 16.3 g (75.0 mmol) of CA-3, 23.0 g of NMP and GBL were added and reacted at 50 ° C. for 15 hours to obtain a polyamic acid solution (PAA-2). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 370 mPa · s.

(Synthesis Example 4)
To a 1 L separable flask equipped with a stirrer and a nitrogen introduction tube, 42.7 g (175 mmol) of DA-1 and 59.7 g (175 mmol) of DA-4 were added, 586 g of NMP was added, and the mixture was stirred while feeding nitrogen. And dissolved. While stirring this diamine solution, 74.5 g (332 mmol) of CA-4 was added, 230 g of NMP was further added, and the mixture was stirred at room temperature for 24 hours to obtain a polyamic acid solution (PAA-3). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 832 mPa · s.
Into a 1 L Erlenmeyer flask containing a stir bar, 200 g of this polyamic acid solution (PAA-3) was taken, 100 g of NMP, 21.8 g of acetic anhydride and 2.81 g of pyridine were added, and the mixture was stirred at room temperature for 30 minutes. Then, it was made to react at 60 degreeC for 3 hours. This reaction solution was put into 700 g of methanol, and the resulting 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 polyimide powder. The imidation ratio of this polyimide powder was 68%.
Into a 200 mL Erlenmeyer flask containing a stir bar, 32.7 g of this polyimide powder was taken, 240 g of NMP was added, and the mixture was stirred and dissolved at 70 ° C. for 20 hours to obtain a polyimide solution (SPI-1). It was.

(Synthesis Example 5)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 7.14 g (31.0 mmol) of DA-2 was added, 32 g of NMP and GBL were added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 2.33 g (9.30 mmol) of CA-5, 6.00 g of NMP and GBL were added, and the mixture was stirred at 40 ° C. for 12 hours under a nitrogen atmosphere. Further, 6.13 g (20.8 mmol) of CA-6, 6.00 g of NMP and GBL were added, respectively, and stirred at 23 ° C. for 5 hours to obtain a polyamic acid solution (PAA-4). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 787 mPa · s.

(Synthesis Example 6)
To a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 1.37 g (5.60 mmol) of DA-1, 0.908 g (8.40 mmol) of DA-6, 2.17 g of DA-7 ( 8.40 mmol) and 2.23 g (5.60 mmol) of DA-8 were added, 76.8 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 5.99 g (26.7 mmol) of CA-4 was added, and 16.1 g of NMP was further added, followed by stirring at room temperature for 24 hours to obtain a polyamic acid solution (PAA-5). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 397 mPa · s.

(Synthesis Example 7)
In a 500 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 15.9 g (80.0 mmol) of DA-5 and 5.96 g (20.0 mmol) of DA-3 were added, 230 g of NMP was added, and nitrogen was added. The solution was stirred and dissolved while feeding. While stirring this diamine solution under water cooling, 4.41 g (22.5 mmol) of CA-1 was added, 12.3 g of NMP was added, and the mixture was stirred at 40 ° C. for 12 hours. Further, 18.8 g (75.0 mmol) of CA-5 and 13.2 of NMP were added, and stirred at 50 ° C. for 10 hours to obtain a polyamic acid solution (PAA-6). The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 1405 mPa · s.

(Synthesis Example 8)
In a 500 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 26.8 g (89.8 mmol) of DA-3 and 9.01 g (60.0 mmol) of DA-9 were added, 290 g of NMP was added, and nitrogen was added. The solution was stirred and dissolved while feeding. While stirring this diamine solution under water cooling, 27.9 g (142 mmol) of CA-1 was added, 71.4 g of NMP was added and stirred at 23 ° C. for 2 hours to obtain a polyamic acid solution (PAA-7). . The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 750 mPa · s.

(Synthesis Example 9)
In a 200 mL four-necked flask equipped with a stirrer and a nitrogen introduction tube, 9.96 g (50.0 mmol) of DA-5 was weighed, 132 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution under water cooling, 8.82 g (45.0 mmol) of CA-1 was added, 36.0 g of NMP was further added, and the mixture was stirred at 23 ° C. for 5 hours under a nitrogen atmosphere to obtain a polyamic acid solution ( PAA-8) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 ° C. was 164 mPa · s.

Example 1
In a 50 mL Erlenmeyer flask containing a stir bar, 15.2 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, 9.44 g of NMP, and 1-glycidoxypropyltriethoxysilane were added. 1.48 g of an NMP solution containing 10% by mass, 0.357 g of an NMP solution containing 10% by mass of AD-1, and 6.62 g of BCS were added, and the mixture was stirred for 2 hours with a magnetic stirrer. )

(Example 2)
In a 50 mL Erlenmeyer flask containing a stir bar, 7.30 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 2 was collected, 3.18 g of NMP, 1.75 g of GBL, 3-glycidide. Add 0.750 g of NMP solution containing 1% by mass of xylpropyltriethoxysilane, 0.422 g of NMP solution containing 10% by mass of AD-1, and 3.35 g of BCS, and stir with a magnetic stirrer for 2 hours. A liquid crystal aligning agent (A-2) was obtained.

(Example 3)
In a 50 mL Erlenmeyer flask containing a stir bar, 7.30 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 2 was collected, 3.24 g of NMP, 1.75 g of GBL, 3-glycidide. Add 0.750 g of NMP solution containing 1% by mass of xylpropyltriethoxysilane, 0.362 g of NMP solution containing 10% by mass of AD-2, and 3.35 g of BCS, and stir with a magnetic stirrer for 2 hours. A liquid crystal aligning agent (A-3) was obtained.

(Example 4)
In a 50 mL Erlenmeyer flask containing a stir bar, 7.30 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 2 was collected, 3.00 g of NMP, 1.75 g of GBL, 3-glycidide. Add 0.750 g of NMP solution containing 1% by mass of xylpropyltriethoxysilane, 0.596 g of NMP solution containing 10% by mass of AD-2, and 3.35 g of BCS, and stir with a magnetic stirrer for 2 hours. A liquid crystal aligning agent (A-4) was obtained.

(Example 5)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. , 3.79 g of NMP, 2.05 g of GBL, 0.750 g of NMP solution containing 1% by mass of 3-glycidoxypropyltriethoxysilane, 0.100 g of NMP solution containing 10% by mass of AD-1, and 3.35 g of BCS was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-5).

(Example 6)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. , 3.69 g of NMP, 2.05 g of GBL, 0.750 g of NMP solution containing 1% by mass of 3-glycidoxypropyltriethoxysilane, 0.210 g of NMP solution containing 10% by mass of AD-1, and 3.35 g of BCS was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-6).

(Example 7)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. NMP 3.72 g, GBL 2.05 g, 3-glycidoxypropyltriethoxysilane 1 wt% NMP solution 0.750 g, AD-2 10 wt% NMP solution 0.180 g, and 3.35 g of BCS was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-7).

(Example 8)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. NMP 3.54 g, GBL 2.05 g, 3-glycidoxypropyltriethoxysilane 1 wt% NMP solution 0.750 g, AD-2 10 wt% NMP solution 0.360 g, and 3.35 g of BCS was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-8).

Example 9
In a 50 mL Erlenmeyer flask containing a stir bar, 2.63 g of the polyimide solution (SPI-1) obtained in Synthesis Example 4 and 4.62 g of the polyamic acid solution (PAA-4) obtained in Synthesis Example 5 were collected. , 3.32 g of NMP, 3.45 g of GBL, 0.297 g of NMP solution containing 10% by weight of AD-1, 3.60 g of PB, 0.139 g of AD-4, and 0.139 g of AD-4. By stirring for a while, a liquid crystal aligning agent (A-9) was obtained.

(Example 10)
In a 50 mL Erlenmeyer flask containing a stirring bar, 2.79 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 and 3.60 g of the polyamic acid solution (PAA-6) obtained in Synthesis Example 7 were taken. . 0.45 g of NMP solution containing 5.85 g of NMP, 10% by mass of AD-1 and 5.40 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-10).

(Example 11)
In a 50 mL Erlenmeyer flask containing a stir bar, 9.97 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 6 and 7.43 g of the polyamic acid solution (PAA-7) obtained in Synthesis Example 8 were taken. . Add 2.29 g of NMP, 2.20 g of NMP solution containing 1% by mass of 3-glycidoxypropyltriethoxysilane, 1.10 g of NMP solution containing 10% by mass of AD-3, and 12.0 g of BCS. The mixture was stirred with a tic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-11).

(Comparative Example 1)
In a 50 mL Erlenmeyer flask containing a stir bar, 15.2 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was fractioned, 9.80 g of NMP, and 1 of 3-glycidoxypropyltriethoxysilane. 1.48 g of NMP solution containing 5% by mass and 6.62 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-1).

(Comparative Example 2)
In a 50 mL Erlenmeyer flask containing a stir bar, 15.2 g of the polyamic acid solution (PAA-8) obtained in Synthesis Example 9 was collected, 10.2 g of NMP, and 1 of 3-glycidoxypropyltriethoxysilane. Add 1.58 g of NMP solution containing 10% by mass, 0.316 g of NMP solution containing 10% by mass of AD-1, and 7.04 g of BCS, and stir with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-2 )

(Comparative Example 3)
In a 50 mL Erlenmeyer flask containing a stir bar, 7.72 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 2 was collected, 3.18 g of NMP, 1.75 g of GBL, 3-glycidide. 0.750 g of an NMP solution containing 1% by mass of xylpropyltriethoxysilane and 3.35 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-3).

(Comparative Example 4)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. Then, 3.89 g of NMP, 2.05 g of GBL, 0.750 g of NMP solution containing 1% by mass of 3-glycidoxypropyltriethoxysilane, and 3.35 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 2 hours. As a result, a liquid crystal aligning agent (B-4) was obtained.

(Comparative Example 5)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. NMP 3.64 g, GBL 2.05 g, 3-glycidoxypropyltriethoxysilane 1 wt% NMP solution 0.750 g, AD-5 10 wt% NMP solution 0.260 g, and 3.35 g of BCS was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-5).

(Comparative Example 6)
In a 50 mL Erlenmeyer flask containing a stir bar, 2.19 g of the polyimide solution (PAE-1) obtained in Synthesis Example 2 and 4.51 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 were fractionated. NMP 3.60 g, GBL 2.05 g, 3-glycidoxypropyltriethoxysilane 1 wt% NMP solution 0.750 g, AD-6 10 wt% NMP solution 0.300 g, and 3.35 g of BCS was added and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-6).

(Example 12)
The liquid crystal aligning agent (A-1) obtained in Example 1 was subjected to pressure filtration with a membrane filter having a pore diameter of 1 μm, and then spin-coated on the ITO surface of a glass substrate having an ITO electrode on the entire surface, and the temperature was adjusted to 80 ° C. Dry on hot plate for 2 minutes. Thereafter, baking was performed in an IR oven at 230 ° C. for 20 minutes to form a coating film having a thickness of 100 nm to obtain a substrate with a liquid crystal alignment film.

<Evaluation of pencil hardness>
The obtained substrate with a liquid crystal alignment film was measured with a pencil hardness test method (JIS K5400), and the result was 2H, which was good.
A method for manufacturing a liquid crystal cell for evaluating the liquid crystal alignment will be described below.
A liquid crystal cell having a configuration of an FFS liquid crystal display element is manufactured. First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 35 mm and a thickness of 0.7 mm. On the substrate, an IZO electrode constituting the counter electrode as the first layer is formed on the entire surface. 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 IZO film is arranged as a third layer on the second layer SiN film to form two pixels, a first pixel and a second pixel. is doing. 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 bow shape with a bent central portion. 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-shaped electrode elements having a bent central portion, the shape of each pixel is not a rectangular shape, and the central portion is similar to the electrode element. It has a shape similar to that of a bold, bent, bent at 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, the liquid crystal aligning agent (A-1) obtained in Example 1 was filtered through a 1.0 μm filter, and then applied to the prepared substrate with electrodes by spin coating. After drying on an 80 ° C. hot plate for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C. for 20 minutes to obtain a polyimide film having a thickness of 60 nm. This polyimide film is rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm / sec, indentation length: 0.3 mm, rubbing direction: inclined by 10 ° with respect to the third-layer IZO comb-teeth electrode Then, ultrasonic cleaning was performed for 1 minute in pure water for cleaning, and water droplets were removed by air blow. Then, it dried for 15 minutes at 80 degreeC, and obtained the board | substrate with a liquid crystal aligning film. Also, as a counter substrate, a polyimide film is formed on a glass substrate having an ITO electrode on the back surface and having a columnar spacer with a height of 4 μm in the same manner as described above. A substrate with a liquid crystal alignment film was obtained. One set of these two substrates with a liquid crystal alignment film is printed, and the sealant is printed on the substrate leaving the liquid crystal injection port. The other substrate has the liquid crystal alignment film surface facing and the rubbing direction is antiparallel. They were pasted together. Thereafter, the sealing agent was cured to produce an empty cell having a cell gap of 4 μm. 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 liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand at 23 ° C. overnight, and then used for evaluation of liquid crystal alignment.

<Evaluation of liquid crystal alignment>
Using this liquid crystal cell, an AC voltage of 10 VPP was applied at a frequency of 30 Hz in a constant temperature environment of 60 ° C. for 168 hours. 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 region of the first pixel became darkest to the angle at which the first region became darkest was calculated as an angle Δ. Similarly, for the second pixel, the second area was compared with the first area, and a 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. When the value of the angle Δ of the liquid crystal cell exceeded 0.6 degrees, it was defined as “defective” and evaluated. When the value of the angle Δ of the liquid crystal cell did not exceed 0.6 degrees, it was defined as “good” and evaluated.
Further, when the liquid crystal alignment was evaluated in the liquid crystal cell treated as described above, Δ was 0.10 °, which was favorable.

(Example 13)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-2) obtained in Example 2 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.15 °, which was favorable.

(Example 14)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-3) obtained in Example 3 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.13 °, which was favorable.

(Example 15)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-4) obtained in Example 4 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.17 °, which was favorable.

(Example 16)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-5) obtained in Example 5 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.41 °, which was favorable.

(Example 17)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-6) obtained in Example 6 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.45 °, which was favorable.

(Example 18)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-7) obtained in Example 7 was used.
Further, when the liquid crystal orientation was evaluated in the same manner as in Example 12, Δ was 0.43 °, which was favorable.

(Example 19)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (A-8) obtained in Example 8 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.49 °, which was favorable.

(Example 20)
The liquid crystal aligning agent (A-9) obtained in Example 9 was subjected to pressure filtration with a membrane filter having a pore diameter of 1 μm, and then spin-coated on the ITO surface of a glass substrate having an ITO electrode on the entire surface, and the temperature was 80 ° C. For 2 minutes on a hot plate. Thereafter, the film was baked for 20 minutes in a hot air circulating oven at a temperature of 230 ° C. to obtain an imidized film having a thickness of 110 nm. The fired film was irradiated with 200 mJ / cm ^{2 of} 254 nm ultraviolet light through a polarizing plate. Thereafter, the substrate was washed with a mixed solvent of IPA / water = 1: 1 for 5 minutes and further baked for 20 minutes in a 230 ° C. hot air circulation oven. Thereby, a substrate with a liquid crystal alignment film was obtained.
As a result of evaluating the pencil hardness in the same manner as in Example 12, it was 2H, which was favorable.

After the liquid crystal aligning agent (A-9) obtained in Example 9 was filtered through a 1.0 μm filter, it was spin-coated on the electrode-attached substrate described in Example 12, and 2 on a hot plate at a temperature of 80 ° C. Let dry for minutes. Thereafter, the film was baked for 20 minutes in a hot air circulating oven at a temperature of 230 ° C. to obtain an imidized film having a thickness of 110 nm. The fired film was irradiated with 200 mJ / cm ^{2 of} 254 nm ultraviolet light through a polarizing plate. Thereafter, the substrate was washed with a mixed solvent of IPA / water = 1: 1 for 5 minutes and further baked for 20 minutes in a 230 ° C. hot air circulation oven. Thereby, a substrate with a liquid crystal alignment film was obtained.

Thereafter, in the same manner as described in Example 12, two substrates with a liquid crystal alignment film were prepared, and empty cells having a cell gap of 4 μm were prepared. 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 liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand at 23 ° C. overnight, and then used for evaluation of liquid crystal alignment.
When the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.10 °, which was favorable.

(Example 21)
The liquid crystal aligning agent (A-10) obtained in Example 10 was subjected to pressure filtration with a membrane filter having a pore size of 1 μm, and then spin-coated on the ITO surface of a glass substrate having an ITO electrode on the entire surface, and the temperature was 80 ° C. For 2 minutes on a hot plate. Thereafter, the film was baked for 30 minutes in a hot air circulating oven at a temperature of 230 ° C. to obtain an imidized film having a thickness of 100 nm. The fired film was irradiated with UV light of 254 nm through a polarizing plate at 150 mJ / cm ² . Thereafter, baking was further performed in a hot air circulation oven at 230 ° C. for 30 minutes. Thereby, a substrate with a liquid crystal alignment film was obtained.
As a result of evaluating the pencil hardness in the same manner as in Example 12, it was 4H, which was favorable.

The liquid crystal aligning agent (A-10) obtained in Example 10 was filtered through a 1.0 μm filter, and then spin-coated on the electrode-attached substrate described in Example 11, and 2 on a hot plate at a temperature of 80 ° C. Let dry for minutes. Thereafter, the film was baked for 30 minutes in a hot air circulating oven at a temperature of 230 ° C. to obtain an imidized film having a thickness of 100 nm. The fired film was irradiated with UV light of 254 nm through a polarizing plate at 150 mJ / cm ² . Thereafter, baking was further performed in a hot air circulation oven at 230 ° C. for 30 minutes. Thereby, a substrate with a liquid crystal alignment film was obtained.

Thereafter, in the same manner as described in Example 12, two substrates with a liquid crystal alignment film were prepared, and empty cells having a cell gap of 4 μm were prepared. 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 liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand at 23 ° C. overnight, and then used for evaluation of liquid crystal alignment.
When the liquid crystal orientation was evaluated in the same manner as in Example 12, Δ was 0.21 ° and was good.

(Example 22)
The pencil hardness was evaluated in the same manner as in Example 21 except that the liquid crystal aligning agent (A-11) obtained in Example 11 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 21, Δ was 0.13 °, which was favorable.

(Comparative Example 7)
The pencil hardness was evaluated by the same method as in Example 12 except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 1 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.05 °, which was favorable.

(Comparative Example 8)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (B-2) obtained in Comparative Example 2 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 1.5 °, which was poor.

(Comparative Example 9)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (B-3) obtained in Comparative Example 3 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.11 °, which was favorable.

(Comparative Example 10)
The pencil hardness was evaluated by the same method as in Example 12 except that the liquid crystal aligning agent (B-4) obtained in Comparative Example 4 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.45 °, which was favorable.

(Comparative Example 11)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (B-5) obtained in Comparative Example 5 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.86 °, which was poor.

(Comparative Example 12)
The pencil hardness was evaluated in the same manner as in Example 12 except that the liquid crystal aligning agent (B-6) obtained in Comparative Example 4 was used.
Further, when the liquid crystal alignment was evaluated in the same manner as in Example 12, Δ was 0.65 °, which was poor.
Table 1 shows the results of evaluation of pencil hardness and evaluation of liquid crystal orientation when the liquid crystal aligning agents obtained in Examples and Comparative Examples are used.

Claims

The following formula (1) (in formula (1), X 1 is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y 1 is derived from diamine, and the following formula (2) (in formula (2): R 2 is a single bond or a divalent organic group, and R 3 has a structure represented by — (CH 2 ) n — (where n is an integer of 2 to 20, and any —CH 2 — Each may be replaced with an ether, ester, amide, urea, or carbamate bond under non-adjacent conditions.), R 4 is a single bond or a divalent organic group, and any hydrogen atom on the benzene ring is 1 And a polyimide having a structural unit represented by the following formula: R 1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) Selected from the group consisting of a precursor and an imidized polymer of the polyimide precursor Polymer comprising at least one that,
A liquid crystal aligning agent comprising a compound represented by the following formula (3) (wherein p is an integer of 1 to 6 in formula (3)) and an organic solvent.
The liquid crystal aligning agent of Claim 1 with which X1 in the said Formula (1) is chosen from the following structures.
The liquid crystal aligning agent of Claim 1 or Claim 2 from which the said Formula (2) is chosen from the following structures.
In the polyimide precursor containing the structural unit represented by the formula (1) and the imidized polymer of the polyimide precursor, the structural unit represented by the formula (1) and a structural unit obtained by imidizing the structural unit are selected. The liquid crystal according to any one of claims 1 to 3, wherein a ratio of at least one structural unit is 20 mol% to 100 mol% with respect to 1 mol of all structural units in the polymer. Alignment agent.
The liquid crystal aligning agent of any one of Claims 1-4 whose compound of the said Formula (3) is at least 1 sort (s) chosen from the following structures.
The liquid crystal aligning agent according to any one of claims 1 to 5, wherein the compound represented by the formula (3) is contained in an amount of 1 to 20 parts by weight based on the weight of the whole polymer.
A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 6.
A liquid crystal display device comprising the liquid crystal alignment film according to claim 7.