WO2019107518A1

WO2019107518A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: WO2019107518A1
Application number: PCT/JP2018/044087
Authority: WO
Inventors: 研造矢田; 暁子杉山
Original assignee: 日産化学株式会社
Priority date: 2017-11-30
Filing date: 2018-11-29
Publication date: 2019-06-06
Also published as: TW201936789A; JPWO2019107518A1; TWI744574B; CN111386494B; CN111386494A; JP7193782B2; KR20200088846A

Abstract

A liquid crystal alignment agent containing at least one type of polymer selected from a polyimide and a polyimide precursor in which a polymer main chain terminal has a structure represented by formula (1). In the formula, R1 represents a C1-20 organic group which may contain an acrylic group, a methyl methacrylate group, or other photoreactive functional group at a terminal thereof.

Description

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

The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display device.

Liquid crystal display devices are known as lightweight, thin and low power consumption display devices. In recent years, high-definition liquid crystal display devices for mobile phones and tablet-type terminals, which have been rapidly increasing their share, have achieved remarkable development that high display quality is required.

The liquid crystal display element is configured by sandwiching a liquid crystal layer by a pair of transparent substrates provided with electrodes. And in a liquid crystal display element, the organic film which consists of organic materials is used as a liquid crystal aligning film so that a liquid crystal may be in a desired orientation state between board | substrates. That is, the liquid crystal alignment film is a component of the liquid crystal display element, and is formed on the surface of the substrate holding the liquid crystal in contact with the liquid crystal, and plays a role of orienting the liquid crystal in a certain direction between the substrates.
In recent years, liquid crystal display devices have been used for mobile applications such as smartphones and mobile phones. In these applications, in order to secure as many display surfaces as possible, it is necessary to narrow the width of the sealing agent used to bond the substrates of the liquid crystal display element as compared with the prior art. Furthermore, for the reason described above, it is also required to position the sealing agent at a position in contact with the end of the liquid crystal alignment film having weak adhesion to the sealing agent, or at the top of the liquid crystal alignment film. In such a case, particularly when used under high temperature and high humidity conditions, water is likely to be mixed in between the sealing agent and the liquid crystal alignment film, and display unevenness occurs in the vicinity of the frame of the liquid crystal display element.
In order to solve this problem, a liquid crystal aligning agent using an additive having a specific structure has been proposed (see Patent Document 1).

WO2015 / 072554

However, in recent years, further improvement in adhesion between the liquid crystal alignment film and the sealing agent is required.

Among them, it is known that in the property improvement from the sealing agent, it is difficult to simultaneously achieve the adhesion property between the sealing agent and the liquid crystal alignment film and the moisture permeation preventing property of the sealing agent. Characteristic improvement is required.
Therefore, an object of the present invention is to provide a liquid crystal aligning agent capable of enhancing the adhesion between a sealing agent and a liquid crystal aligning film and suppressing the occurrence of display unevenness in the vicinity of a frame of a liquid crystal display element under high temperature and high humidity conditions. I assume.

Thus, the present invention is based on the above findings and has the following summary.
1. The liquid-crystal aligning agent containing a polymer precursor in which a polymer principal chain terminal has a structure of following formula (1), and at least 1 sort (s) of polymer chosen from polyimide.

R ₁ represents an organic group having 1 to 20 carbon atoms which may contain a photoreactive functional group such as an acryl group or a methyl methacrylate group at its terminal.

By using the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal alignment film capable of enhancing the adhesion between the sealing agent and the liquid crystal alignment film and suppressing the occurrence of display unevenness near the frame of the liquid crystal display element under high temperature and high humidity conditions. . The liquid crystal display device having this liquid crystal alignment film can solve the display unevenness in the vicinity of the frame by enhancing the adhesion between the sealing agent and the liquid crystal alignment film, and can be suitably used for a large screen and high definition liquid crystal display.

It is a figure showing the preparation methods of the evaluation sample produced when performing the adhesiveness evaluation of the liquid crystal aligning film obtained using the liquid crystal aligning agent of this invention. Details will be described later.

<Terminal structure>
The liquid crystal aligning agent of the present invention contains at least one polymer selected from a polyimide precursor and a polyimide having a structure of the following formula (1) at the polymer main chain terminal.

R ₁ represents an organic group having 1 to 20 carbon atoms which may contain a photoreactive functional group such as an acryl group or a methyl methacrylate group at its terminal.
Here, R ₁ is preferably a group selected from the following structures R-1 to R-10.

In order to introduce such a structure into the polyimide, it is preferable to use a compound such as the following formula (2) during and after the polymerization of the polyimide precursor.

Specific examples of the compound of the formula (2) include the compounds of Z-1 to Z-10 exemplified below, but Z-1 is more preferable in view of seal adhesion and rubbing resistance, and Z-2 is more preferable. Particularly preferred.

<Tetracarboxylic acid derivative>
The polyimide precursor contained in the liquid crystal aligning agent of the present invention is obtained from the reaction of a tetracarboxylic acid derivative and a diamine, and the polyimide contained in the liquid crystal aligning agent of the present invention imidizes the polyimide precursor. Obtained by Hereinafter, specific examples of the materials to be used and the production method will be described in detail.
Not only tetracarboxylic acid dianhydrides but also tetracarboxylic acid dianhydrides, tetracarboxylic acid dihalide compounds, tetracarboxylic acid dialkyl esters and tetracarboxylic acid dialkyl esters are used as tetracarboxylic acid derivatives used for producing polyimide precursors Ester dihalides are mentioned.
Among the tetracarboxylic dianhydrides or derivatives thereof, those represented by the following formula (3) are preferable.

The structure of X ₁ is not particularly limited. Preferred specific examples include the following formulas (X1-1) to (X1-44). Among them, (X1-1), (X1-5), (X1-8) and (X1-27) are particularly preferable.

In formulas (X1-1) to (X1-4), R ₃ to R ₂₃ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, It is an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. From the viewpoint of liquid crystal alignment, R ₃ to R ₂₃ are preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, and particularly preferably a hydrogen atom or a methyl group.
Specific examples of the formula (X1-1) include the following formulas (X1-1-1) to (X1-1-6). (X1-1-1) is particularly preferable from the viewpoint of liquid crystal alignment and sensitivity of photoreaction.

<Diamine>
The diamine used for manufacture of a polyimide precursor is represented by following formula (4).

Each of A ₁ and A ₂ independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms.
The structure of Y ₁ is not particularly limited. Preferred structures include the following (Y-1) to (Y-182).

In the above formulae, Me represents a methyl group, and R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms.

Among them, the structure of Y ₁ is (Y-7), (Y-8), (Y-16), (Y-17), (Y-18), (Y-20), (Y-21). ), (Y-22), (Y-28), (Y-35), (Y-38), (Y-43), (Y-48), (Y-64), (Y-66), (Y-71), (Y-72), (Y-76), (Y-77), (Y-80), (Y-81), (Y-82), (Y-83), (Y) (-156), (Y-159), (Y-160), (Y-161), (Y-162), (Y-168), (Y-169) and (Y-170) are preferable, and in particular, (Y-7), (Y-8), (Y-16), (Y-17), (Y-18), (Y-21), (Y-22), (Y-28), (Y) -38), (Y-64), (Y-66), (Y-72), (Y-76) ), (Y-81), (Y-156), (Y-159), (Y-160), (Y-161), (Y-162), (Y-168), (Y-169), (Y-170), (Y-171), (Y-173) and (Y-175) are preferable.

<Polyamic acid>
The polyamic acid which is a polyimide precursor used for this invention can be manufactured by the method shown below. Specifically, a tetracarboxylic dianhydride and a 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 by Further, during and / or after the polymerization, the compound shown in the above (2) is reacted to obtain a polyimide precursor having a specific structure introduced at the end.

The organic solvent used for the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or γ-butyrolactone in view of solubility of monomers and polymers, and one or more of these may be mixed You may use. The concentration of the polymer is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight polymer is easily obtained.

The polyamic acid obtained as described above can be recovered by precipitating a polymer by injecting the reaction solution into a poor solvent while well stirring it. Further, precipitation is carried out several times, and after washing with a poor solvent, it is possible to obtain a purified polyamic acid powder by normal temperature or heat drying. The poor solvent is not particularly limited, and water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene and the like can be mentioned.

<Polyamic acid ester>
The polyamic acid ester which is one of the polyimide precursors used for this invention can be manufactured by the method of (I), (II) or (III) shown below. Further, during and / or after the polymerization, the compound shown in the above (2) is reacted to obtain a polyimide precursor having a specific structure introduced at the end.

(I) When manufacturing from polyamic acid
The polyamic acid ester can be synthesized by esterification of a polyamic acid obtained from tetracarboxylic acid 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. It can be synthesized.

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

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

(II) When manufactured by reaction of tetracarboxylic acid diester dichloride and diamine Polyamic acid ester can be manufactured 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 reaction.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds mildly. The amount of the base used 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 for the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in view of the solubility of monomers and polymers, and these may be used alone or in combination of two or more. The concentration of the polymer in the reaction solution is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, from the viewpoint that precipitation of the polymer hardly occurs and a polymer can be easily obtained. Further, in order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent the mixing of outside air in a nitrogen atmosphere.

(III) When manufactured by reaction of tetracarboxylic acid diester and diamine Polyamic acid ester can be manufactured by polycondensing tetracarboxylic acid diester and diamine. Specifically, a tetracarboxylic acid diester and a 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 be produced by reacting for time.

Examples of the condensing agent include triphenyl phosphite, dicyclohexyl carbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N′-carbonyldiimidazole, dimethoxy-1,3,5-triadidi Nylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazol-1-yl) -N, N And N ′, N′-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate and the like can be used. The addition amount of the condensing agent is preferably 2 to 3 moles per mol of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base used is preferably 2 to 4 moles per mole of the diamine component from the viewpoint of easy removal and high molecular weight.

In the above reaction, the reaction proceeds efficiently by adding a 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 molar amount with respect to the diamine component.

Among the three methods for producing the polyamic acid ester, the method for producing the above (I) or the above (II) is particularly preferable because a high molecular weight polyamic acid ester can be obtained.

The solution of the polyamic acid ester obtained as described above can precipitate the polymer by pouring it into a poor solvent while stirring well. Precipitation is carried out several times, and after washing with a poor solvent, it is possible to obtain a purified polyamic acid ester powder at room temperature or by heating and drying. The poor solvent is not particularly limited, and water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene and the like can be mentioned.

<Polyimide>
The polyimide used in the present invention can be produced by imidizing the above-mentioned polyamic acid or polyamic acid ester. The imidation ratio of the polyimide used in the present invention is not limited to 100%. From the viewpoint of electrical characteristics, 20 to 99% is preferable. When producing a polyimide from polyamic acid ester, chemical imidization which adds a basic catalyst to the polyamic acid solution obtained by dissolving the said polyamic acid ester solution or 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 molecular weight reduction of the polymer does not easily occur in the imidization process.

Chemical imidization can be carried out by stirring the polyamic acid or polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. Moreover, the polyimide precursor which introduce | transduced the specific structure at the terminal can be obtained by making the compound shown by said (2) react at that time. As an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine and trioctylamine. Among them, pyridine is preferable because it has a suitable basicity to allow the reaction to proceed. Further, as the acid anhydride, acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like can be mentioned, and it is preferable to use acetic anhydride among them because purification after completion of the reaction becomes easy. Generally, in the case of conventional polyimide, acetylation can be suppressed in the present invention, while acetyl group is formed at the main chain end when acetic anhydride is used.

The temperature at which the imidization reaction is carried out is, for example, −20 ° C. to 120 ° 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 group, and the amount of the acid anhydride is 1 to 50 moles, preferably 3 to 30 moles of the amic acid group. It is a double. The imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature and reaction time.

Since the added catalyst and the like remain in the solution after the imidization reaction of the polyamic acid ester or the polyamic acid, the obtained imidized polymer is recovered by the means described below, and redissolved in an organic solvent. Preferably, the liquid crystal aligning agent of the present invention is used.

The solution of the polyimide obtained as mentioned above can precipitate a polymer by inject | pouring into a poor solvent, stirring it well. Precipitation is carried out several times, and after washing with a poor solvent, it is possible to obtain a purified polyamic acid ester powder at room temperature or by heating and drying.

The poor solvent is not particularly limited, and methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene and the like can be mentioned.

<Liquid crystal alignment agent>
The liquid crystal aligning agent of the present invention has the form of a solution in which a polymer containing a specific polymer is dissolved in an organic solvent containing a specific solvent. The molecular weight of the polyimide precursor and the polyimide described in the present invention is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100, in weight average molecular weight. , 000. Also, 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 concentration of the polymer of the liquid crystal aligning agent used in the present invention can be appropriately changed by setting the thickness of the coating film to be formed, but from the point of forming a uniform and defect-free coating film, 1 weight % Or more is preferable, and from the viewpoint of storage stability of the solution, 10% by weight or less is preferable.

The solvent in the liquid crystal aligning agent of the present invention is a solvent that dissolves a polyimide precursor and a polyimide (also referred to as a good solvent) or a solvent that improves the coating properties and surface smoothness of the liquid crystal alignment film when the liquid crystal aligning agent is applied. (Also referred to as a poor solvent) is preferably used. Specific examples of other solvents are listed below, but are not limited to these examples.

Specific examples of the good solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-butyl-2-pyrrolidone, γ-butyrolactone, γ-valerolactone, 1,3-dimethylimidazolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N, N-dimethylpropanamide or 4-hydroxy-4-methyl-2-pentanone and the like. be able to.
Specific examples of the poor solvent include 1-butoxy-2-propanol, 2-butoxy-1-propanol, 2-propoxyethanol, 2- (2-propoxyethoxy) ethanol, 1-propoxy-2-propanol 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-octano , 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethanediol, 1,2-propanediol, 1 , 3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentane Diol, 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 dimethy 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 Tart, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, butyl cellosolve, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (Hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, 1- (butoxyethoxy) prop Nordol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono Butyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, propylene glycol diacetate, diisopentyl ether, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate Tart, diethylene glycol acetate, triethylene glycol Glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, 3-methoxy Methyl propionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, lactate methyl ester, lactate Ethyl ester, lactic acid n-propyl ester, lactic acid n-butyl ester, lactic acid isoamyl ester, diisobutyl ketone, ethyl carbitol and the like can be mentioned.
Moreover, as a poor solvent, the solvent represented by a following formula is also used preferably.

R _{24 and} R ₂₅ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms. However, R ₂₄ + R ₂₅ is an integer greater than 3.

Further, as the poor solvent, when the solubility of the polyimide precursor and the polyimide contained in the liquid crystal aligning agent in the solvent is high, the solvents represented by the following [D-1] to the formula [D-3] are preferable.

In Formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, and in Formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms, Formula [D-3] among, ^{D 3} is an alkyl group having 1 to 4 carbon atoms.

Further, the liquid crystal aligning agent of the present invention is at least one kind of substitution selected from the group consisting of a crosslinkable compound having an epoxy group, an isocyanate group, an oxetane group or a cyclocarbonate group, a hydroxyl group, a hydroxyalkyl group and a lower alkoxyalkyl group. A crosslinkable compound having a group or a crosslinkable compound having a polymerizable unsaturated bond may be included.

As such a crosslinking compound, various known compounds can be used depending on the purpose. The following compounds are preferably used.

The content of the crosslinkable compound is preferably 0.1 to 150 parts by mass with respect to 100 parts by mass of all the polymer components. Among these, in order for the crosslinking reaction to proceed and to achieve the desired effect, 0.1 to 100 parts by mass is preferable, and 1 to 50 parts by mass is more preferable.

The liquid crystal aligning agent of this invention can contain the compound which improves the uniformity of the film thickness of a liquid crystal aligning film at the time of apply | coating a liquid crystal aligning agent, and surface smoothness.

As a compound which improves the uniformity of the film thickness of a liquid crystal aligning film, and surface smoothness, a fluorine-type surfactant, a silicone type surfactant, a nonion type surfactant etc. are mentioned.
The amount of surfactant used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 parts by mass, with respect to 100 parts by mass of all polymer components contained in the liquid crystal aligning agent.

<Liquid crystal alignment film, liquid crystal display element>
The liquid crystal aligning film of this invention is a film | membrane obtained by apply | coating said liquid crystal aligning agent to a board | 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, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, or the like can be used. At that time, it is preferable to use a substrate on which an ITO electrode or the like for driving liquid crystal is formed, 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 if it is only on one substrate, and in this case, a material that reflects light such as aluminum can also be used for the electrode.

Industrially, the liquid crystal aligning agent is generally applied by screen printing, offset printing, flexographic printing or ink jet method, and as the other coating methods, dip method, roll coater method, slit coater, etc. Methods, spinner methods or spray methods are known.

After the liquid crystal aligning agent is applied onto the substrate, the solvent can be evaporated by using a heating means such as a hot plate, a thermal circulation type oven or an IR (infrared) type oven to form a liquid crystal alignment film. The drying and baking steps after the application of the liquid crystal aligning agent can be performed at any temperature and time. Usually, in order to sufficiently remove the contained solvent, baking is carried out at 50 to 120 ° C. for 1 to 10 minutes, followed by baking at 150 to 300 ° C. for 5 to 120 minutes. The thickness of the liquid crystal alignment film after firing is preferably 5 to 300 nm, and more preferably 10 to 200 nm, because if it is too thin, the reliability of the liquid crystal display element may decrease.

The liquid crystal aligning agent of the present invention can be used as a liquid crystal alignment film without application of alignment treatment in a vertical alignment application or the like after being coated and baked on a substrate and then subjected to alignment treatment by rubbing treatment or photo alignment treatment. A known method or apparatus can be used in alignment treatment such as rubbing treatment or light alignment treatment.
As an example of a method of manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure is described as an example. It may be a liquid crystal display element of an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting an image display.

Specifically, 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, for example, ITO electrodes, and are patterned to provide a desired image display. Then, 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 of SiO ₂ -TiO ₂ formed by a sol-gel method.

Next, a liquid crystal alignment film is formed on each substrate, the other substrate is superimposed on one of the substrates so that the liquid crystal alignment film faces each other, and the periphery is bonded with a sealing agent. In order to control the substrate gap, it is usually preferable to mix a spacer in the sealing agent, and to disperse the substrate gap control spacer also in the in-plane portion where the sealing agent is not provided. An opening capable of being filled with liquid crystal from the outside is provided in part of the sealing agent. Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealing agent through the opening provided in the sealing agent, and then the opening is sealed with an adhesive. For injection, a vacuum injection method may be used, or a method utilizing capillary action in the atmosphere may be used. The liquid crystal material may be either a positive liquid crystal material or a negative liquid crystal material, preferably a negative liquid crystal material. Next, the polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surface of the two substrates opposite to the liquid crystal layer.

EXAMPLES The present invention will be more specifically described below by way of Examples, but the present invention is not limited thereto. The symbol of the compound in the following and the measuring method of each characteristic are as follows.

<Tetracarboxylic acid dianhydride>
CBDA: 1,2,3,4, -cyclobutanetetracarboxylic acid dianhydride
1,3-DM-CBDA: (1,3-dimethyl) -1,2,3,4-cyclobutanetetracarboxylic acid dianhydride BDA: 1,2,3,4-butanetetracarboxylic acid dianhydride BPDA: 3,3'4,4'-biphenyltetracarboxylic dianhydride

<Diamine>
DA-1: bis (4-aminophenoxy) ethane DA-2: tert-butyl bis (4-aminophenyl) carbamate DA-3: di-tert-butyl ((adipoyl bis (azanecyl)) bis (3-amino-6) , 1-phenylene)) dicarbamate
DA-4: para-phenylenediamine DA-5: 5-((4- (4-heptylcyclohexyl) phenoxy) methyl) benzene-1,3-diamine DA-6: 4,4 '-(1H-pyrrole-2, 5-Diyl) dianiline DA-7: 4,4'-diaminodiphenylamine DA-8: 4,4'-diaminodiphenylmethane

<Isothiocyanate>
SCN-1: Ethyl isothiocyanate SCN-2: Allyl isothiocyanate

<Additives>
AD-1: 3-glycidoxypropyltriethoxysilane AD-2: N, N, N ', N'-tetrakis (2-hydroxyethyl) adipamide

<Organic solvent>
NMP: N-methyl-2-pyrrolidone
BCS: Butyl Cellosolve
GBL: γ-butyrolactone

In Examples, the molecular weight and imidation ratio of the polyamic acid, the polyimide precursor and the polyimide were evaluated as follows.

<Molecular weight measurement>
For the molecular weight of polyamic acid and polyimide, a room temperature gel permeation chromatography (GPC) apparatus (GPC-101) manufactured by Showa Denko K. K. and columns manufactured by Shodex (KD-803, KD-805) were used. The measurement conditions are as follows.
Column temperature: 50 ° C
Eluent: N, N'-dimethylformamide (Additive: 30 mmol / L of lithium bromide-hydrate (LiBr · H2O), 30 mmol / L of phosphoric acid / anhydrous crystal (o-phosphoric acid), tetrahydrofuran (THF) ) 10ml / L)
Flow rate: 1.0 ml / min
Standard samples for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight: approximately 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corp., and polyethylene glycol (molecular weight: approximately 12,000, 4 manufactured by Polymer Laboratory) , 000, 1,000)

<Measurement of imidation ratio>
20 mg of polyimide powder is placed in an NMR sample tube (manufactured by Kusano Scientific Co., Ltd., NMR sampling tube standard φ5), and 0.53 ml of deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) is added The solution was sonicated and completely dissolved. For this solution, proton NMR at 500 MHz was measured using an NMR meter (JNW-ECA500) manufactured by Nippon Denshi Datum Co., Ltd. The imidation ratio is determined using a proton derived from a structure which does not change before and after imidization as a reference proton, and a peak integrated value of this proton and a proton peak derived from the NH group of amic acid appearing around 9.0 to 11.0 ppm. It calculated | required by the following Numerical formula (1) using an integral value.

Imidation ratio (%) = (1−α · x / y) × 100 (1)

In the above formula (1), x is a proton peak integrated value derived from the NH group of the amic acid, y is a peak integrated value of the reference proton, and α is the NH group of the amic acid in the case of polyamic acid (imidation ratio is 0%) It is the number ratio of reference protons to one proton.

Synthesis Example 1
1,3-DM-CBDA (12.68 g, 56.6 mmol), DA-2 (10.4 g, 26.1 mmol), DA-3 (7.26 g, 13.1 mmol), DA-1 (11.69 g) (47.9 mmol) in NMP (191.48 g) and reacted at 40 ° C. for 1 hour, and then CBDA (3.67 g, 18.7 mmol) and NMP (16.7 g) are added, and 20-25 The reaction was carried out for 2 hours at .degree. C. to obtain a polyamic acid solution (a). The number average molecular weight of this polyamic acid solution (a) was 11440, and the weight average molecular weight was 23,220.
Ethylic isocyanate (0.45 g, 5.2 mmol) is added to polyamic acid solution (a) (30.0 g) and reacted at 20-25 ° C. for 20 hours to introduce a polyimide precursor having a specific structure introduced at the end of polyamic acid (a- 1) A solution was obtained. NMP is added to this polyimide precursor (a-1) solution (30.0 g) to dilute the content of the polyimide precursor (a-1) to 12% by mass, and then acetic anhydride (as an imidization catalyst) 3.52 g) and pyridine (0.91 g) were added and allowed to react at 50 ° C. for 2.5 hours. The reaction solution was poured into methanol (300 ml) and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried at 100 ° C. under reduced pressure to obtain a specific imidized polymer (A-1) having a specific structure introduced at its end. The imidation ratio of this specific polymer (A-1) was 76%.

Synthesis Example 2
Allyl isothiocyanate (0.51 g, 5.2 mmol) is added to the polyamic acid solution (a) (30.0 g) prepared in Synthesis Example 1 and reacted at 20-25 ° C. for 20 hours to introduce a specific structure at the end of polyamic acid The obtained polyimide precursor (a-2) solution was obtained. NMP is added to this polyimide precursor (a-2) solution (30.0 g) to dilute the content of the polyimide precursor (a-2) to 12% by mass, and then acetic anhydride (as an imidization catalyst) 3.52 g) and pyridine (0.91 g) were added and allowed to react at 50 ° C. for 2.5 hours. The reaction solution was poured into methanol (300 ml) and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried at 100 ° C. under reduced pressure to obtain a specific imidized polymer (A-2) having a specific structure introduced at its end. The imidation ratio of this specific imidation polymer (A-2) was 76%.

Synthesis Example 3
BDA (8.9 g, 45 mmol), DA-5 (14.21 g, 36.0 mmol), DA-4 (5.84 g, 54.0 mmol) are mixed in NMP (164.11 g), 2 at 40 ° C. After being reacted for time, CBDA (8.65 g, 44.1 mmol) and NMP (49.0 g) were added, and reacted at 40 ° C. for 2 hours to obtain a polyamic acid solution (b). The number average molecular weight of this polyamic acid solution (b) was 9,100, and the weight average molecular weight was 34,500. Ethyl isothiocyanate (0.53 g, 10.0 mmol) is added to polyamic acid solution (b) (30.0 g), and it reacts at 20-25 degreeC for 20 hours, The polyimide precursor which introduce | transduced the specific structure into the polyamic acid terminal (b) -1) Obtained a solution. NMP is added to this polyimide precursor (b-1) solution (30.0 g) to dilute the content of the polyimide precursor (b-1) to 7% by mass, and then acetic anhydride (as an imidization catalyst) 5.47 g) and pyridine (1.70 g) were added and reacted at 40 ° C. for 3.5 hours. The reaction solution was poured into methanol (300 ml) and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ° C. to obtain a specific imidized polymer (B-1) having a specific structure introduced at its end. The imidation ratio of this specific imidation polymer (B-1) was 65%.

Synthesis Example 4
Allyl isothiocyanate (0.54 g, 5.4 mmol) is added to the polyamic acid (b) prepared in Synthesis Example 3 and reacted at 20-25 ° C. for 20 hours to introduce a polyimide precursor having a specific structure introduced at the end of the polyamic acid (b) -2) Obtained a solution. NMP is added to this polyimide precursor (b-2) solution (30.0 g) to dilute the content of the polyimide precursor (b-2) to 7% by mass, and then acetic anhydride (as an imidization catalyst) 5.47 g) and pyridine (1.70 g) were added and reacted at 40 ° C. for 3.5 hours. The reaction solution was poured into methanol (300 ml) and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ° C. to obtain a specific imidized polymer (B-2) having a specific structure introduced at its end. The imidation ratio of this specific imidation polymer (B-2) was 65%.

Synthesis Example 5
CBDA (4.20 g, 21.4 mmol), DA-7 (6.68 g, 33.5 mmol), DA-6 (5.01 g, 20.1 mmol), DA-8 (2.66 g, 13.4 mmol) After mixing in NMP (24.65 g) and GBL (111.38 g) and reacting at 40 ° C. for 1 hour, BPDA (11.83 g, 40.2 mmol) and NMP (86.73 g) are added and 50 ° C. The reaction was carried out for 15 hours to obtain a polyamic acid solution (c). The number average molecular weight of this polyamic acid solution (c) was 9370, and the weight average molecular weight was 20,690.

Synthesis Example 6
NMP is added to the polyamic acid solution (a) (30.0 g) prepared in Synthesis Example 1 to dilute the polyamic acid (a) content to 12% by mass, and then acetic anhydride (3 as an imidization catalyst) .52 g) and pyridine (0.91 g) were added and reacted at 50 ° C. for 2.5 hours. The reaction solution was poured into methanol (300 ml) and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ° C. to obtain an imidized polymer (A). The imidation ratio of this imidation polymer (A) was 75%.

Synthesis Example 7
After adding NMP to the polyamic acid solution (b) (30.0 g) prepared in Synthesis Example 3 and diluting it to a polyamic acid (b) content of 7% by mass, acetic anhydride (5 47 g) and pyridine (1.70 g) were added and reacted at 40 ° C. for 3.5 hours. The reaction solution was poured into methanol (300 ml) and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ° C. to obtain an imidized polymer (B). The imidation ratio of this imidation polymer (B) was 65%.

Preparation of liquid crystal aligning agent:
Example 1
NMP (36.6 g) was added to the specific imidation polymer (A-1) (5.0 g) obtained in Synthesis Example 1 and dissolved at 70 ° C. for 20 hours with stirring. NMP (25.1 g) and BCS (16.6 g) were added to this solution, and liquid crystal aligning agent [A] was obtained by stirring at 25 ° C. for 2 hours.

Example 2
NMP (36.6 g) was added to the specific imidated polymer (A-2) (5.0 g) obtained in Synthesis Example 2 and stirred at 70 ° C. for 20 hours for dissolution. NMP (25.1 g) and BCS (16.6 g) were added to this solution, and liquid crystal aligning agent [B] was obtained by stirring at 25 ° C. for 2 hours.

Example 3
NMP (36.6 g) was added to the specific imidated polymer (B-1) (5.0 g) obtained in Synthesis Example 3 and stirred at 70 ° C. for 20 hours for dissolution. NMP (8.4 g) and BCS (33.3 g) were added to this solution, and liquid crystal aligning agent [C] was obtained by stirring at 25 ° C. for 2 hours.

Example 4
NMP (36.6 g) was added to the specific imidation polymer (B-2) (5.0 g) obtained in Synthesis Example 4 and stirred at 70 ° C. for 20 hours for dissolution. NMP (8.4 g) and BCS (33.3 g) were added to this solution, and liquid crystal aligning agent [D] was obtained by stirring at 25 ° C. for 2 hours.

Example 5
NMP (36.6 g) was added to the specific imidated polymer (A-2) (5.0 g) obtained in Synthesis Example 2 and stirred at 70 ° C. for 20 hours for dissolution. This solution (3.63 g) and the polyamic acid solution (c) (8.5 g) obtained in Synthesis Example 5 were weighed, NMP (2.85 g), GBL (5.36 g), BCS (5.1 g), Add 3-glycidoxypropyltriethoxysilane (0.0145 g), N, N, N ', N'-tetrakis (2-hydroxyethyl) adipinamide (0.043 g) and stir at 25 ° C for 2 hours Thus, a liquid crystal aligning agent [E] was obtained.

Comparative Example 1
NMP (36.6 g) was added to the imidated polymer (A) (5.0 g) obtained in Synthesis Example 6 and stirred at 70 ° C. for 20 hours for dissolution. NMP (25.1 g) and BCS (16.6 g) were added to this solution, and liquid crystal aligning agent [F] was obtained by stirring at 25 ° C. for 2 hours.

Comparative Example 2
NMP (36.6 g) was added to the imidated polymer (B) (5.0 g) obtained in Synthesis Example 7 and stirred at 70 ° C. for 20 hours for dissolution. NMP (8.4 g) and BCS (33.3 g) were added to this solution, and liquid crystal aligning agent [G] was obtained by stirring at 25 ° C. for 2 hours.

Comparative Example 3
NMP (36.6 g) was added to the imidated polymer (A) (5.0 g) obtained in Synthesis Example 6 and stirred at 70 ° C. for 20 hours for dissolution. This solution (3.63 g) and the polyamic acid solution (c) (8.5 g) obtained in Synthesis Example 5 were weighed, NMP (2.85 g), GBL (5.36 g), BCS (5.1 g), Liquid crystal alignment is achieved by adding 3-glycidoxypropyltriethoxysilane (0.0145 g), N, N, N ', N'-tetrakis (2-hydroxyethyl) adipinamide and stirring at 25 ° C. for 2 hours. An agent [H] was obtained.

Comparative Example 4
The seal adhesion of Comparative Example 4 is the result of the seal adhesion (N / mm ² ) of the ITO substrate and the sealing agent.

<Preparation of adhesion evaluation sample>
The liquid crystal alignment agent is filtered through a 1.0 μm filter, spin-coated on a 30 mm × 40 mm glass substrate with ITO, dried on an 80 ° C. hot plate for 2 minutes, and baked at 230 ° C. for 20 minutes. A polyimide film having a thickness of 100 nm was obtained. A polyimide film coated substrate and a 30 mm × 40 mm glass substrate with ITO thus obtained are prepared, and a bead spacer having a diameter of 4 μm is dispersed on the polyimide film surface of one of the substrates, and then a UV curable seal is produced. The agent was applied in spots. Next, as shown in FIG. 1, bonding was performed such that the sealing agent was positioned at the center of the overlapping portion of the substrates. At that time, the dropping amount of the sealing agent was adjusted so that the diameter of the sealing agent after bonding was about 3 mm. The two bonded substrates were fixed by clips, irradiated with 3 J of UV by a high pressure mercury lamp, and then thermally cured at 120 ° C. for 1 hour to prepare a sample for evaluation of adhesion.

<Measurement of adhesion>
The upper and lower substrates are fixed at 5 mm wide by upper and lower substrates using the bench type precision universal testing machine (QC-H42A2-S00) manufactured by Yangshuo Technology Co., Ltd. In the direction, the upper substrate was pulled upward, and the pressure (N) at which the seal peeled was measured. The pressure (N) was divided by the area (mm ² ) estimated from the measured diameter of the sealing agent, and the normalized value was used as an index of seal adhesion.

<Evaluation of rubbing resistance>
The liquid crystal alignment agent is filtered through a 1.0 μm filter, spin-coated on a 30 mm × 40 mm glass substrate with ITO, dried on an 80 ° C. hot plate for 2 minutes, and baked at 230 ° C. for 20 minutes. A polyimide film having a thickness of 100 nm was obtained. This polyimide film was rubbed once with a rayon cloth (roll system 120 mm, rotation speed 1000 rpm, moving speed 20 mm / sec, pushing amount 0.6 mm). The surface of the film was observed with an optical microscope, and the presence or absence of scum and scratches was observed at a magnification of 200 times. Those with few scrapes and scratches were defined as "good", and those with many scraps and rubbing scratches were evaluated as "defect".

<Fabrication of liquid crystal cell>
The liquid crystal aligning agents obtained in Examples 1, 2 and 5 and Comparative Examples 1 and 3 were respectively filtered with a filter of 1.0 μm, and a liquid crystal cell was produced in the following procedure. The liquid crystal aligning agent was spin-coated on a glass substrate with ITO, dried on a hot plate at 80 ° C. for 2 minutes, and fired at 230 ° C. for 20 minutes to obtain a coating having a thickness of 100 nm. This polyimide film is rubbed with a rayon cloth (roll diameter 120 mm, rotation speed 1000 rpm, moving speed 20 mm / sec, pushing amount 0.4 mm), and then ultrasonic wave irradiation is performed in pure water for 1 minute, and 80 ° C. for 10 minutes It was dry. After preparing two substrates with a liquid crystal alignment film obtained in this way and placing a 4 μm spacer on the liquid crystal alignment film surface of one of the substrates, combine the two substrates so that the rubbing directions become antiparallel. The periphery was sealed leaving a liquid crystal injection port, and an empty cell having a cell gap of 4 μm was fabricated. Liquid crystal (MLC-2041, manufactured by Merck & Co., Ltd.) was vacuum injected into this cell at normal temperature, and the inlet was sealed to form an anti-parallel liquid crystal cell.

<Fabrication of liquid crystal cell (PSA cell)>
Each of the liquid crystal aligning agents obtained in Examples 3 and 4 and Comparative Example 2 was filtered with a filter of 1.0 μm, and a liquid crystal cell was manufactured by the following procedure. The liquid crystal aligning agent was spin-coated on a glass substrate with ITO, dried on a hot plate at 80 ° C. for 2 minutes, and fired at 230 ° C. for 20 minutes to obtain a coating having a thickness of 100 nm. After preparing two substrates with a liquid crystal alignment film obtained in this way, and placing a 4 μm spacer on the liquid crystal alignment film surface of one of the substrates, combine the two substrates and leave the liquid crystal injection port around the periphery. It sealed and produced the empty cell whose cell gap is 4 micrometers. Liquid crystal (MLC-3023, manufactured by Merck & Co., Ltd.) is vacuum injected into this cell at normal temperature and the injection port is sealed, and then a metal halide lamp with an illuminance of 140 mW is applied to the obtained liquid crystal cell while applying a voltage of 15 V DC. A wavelength of 325 nm or less was cut using the film, ultraviolet light was irradiated at 5 J / cm ^{2 in} terms of 365 nm, and a liquid crystal cell (PSA cell) in which the alignment direction of the liquid crystal was controlled was obtained.

<Liquid crystal orientation>
The alignment state of the produced liquid crystal cell was observed with a polarizing microscope, and those having no alignment defect were regarded as “good”, and those having an alignment defect as “defective”.

The liquid crystal aligning agent of the present invention can solve display unevenness in the vicinity of the frame by improving the adhesion between the sealing agent and the liquid crystal alignment film in a narrow frame liquid crystal display element capable of securing a large number of display surfaces. It is useful.

Claims

The liquid-crystal aligning agent containing a polymer precursor in which a polymer principal chain terminal has a structure of following formula (1), and at least 1 sort (s) of polymer chosen from polyimide.

R 1 represents an organic group having 1 to 20 carbon atoms which may contain a photoreactive functional group such as an acryl group or a methyl methacrylate group at its terminal.
The liquid crystal aligning agent according to claim 1, wherein R 1 is a group selected from the following structures R-1 to R-10.
The polyimide is an imidized polyimide precursor obtained by the reaction of a tetracarboxylic acid derivative component and a diamine component, and the tetracarboxylic acid derivative component contains a tetracarboxylic acid dianhydride represented by the following formula. The liquid crystal aligning agent of Claim 1 or Claim 2.

X 1 represents a tetravalent organic group selected from the following.

R 3 to R 6 each independently contain 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 having 2 to 6 carbon atoms, or a fluorine atom It is a monovalent organic group having 1 to 6 carbon atoms, or a phenyl group.
The polyimide is an imidized polyimide precursor obtained by the reaction of a tetracarboxylic acid derivative component and a diamine component, and a compound of the following formula (2) is added to a solution during and / or after polymerization of the polyimide precursor. The method for producing a polyimide according to any one of claims 1 to 3, which is added.

R 1 is the same as R 1 above.
The method for producing a polyimide according to claim 4, wherein the compound of the formula (2) is selected from the compounds of Z-1 to Z-10 exemplified below.
The liquid crystal aligning film obtained from the liquid crystal aligning agent of any one of Claims 1-3.
The liquid crystal display element which comprises the liquid crystal aligning film of Claim 6.