JP5429236B2 - Liquid crystal alignment agent - Google Patents

Description

  The present invention relates to a liquid crystal aligning agent, and particularly to a liquid crystal aligning agent including a polyimide-polyamic acid having a side chain diamine and a polyamic acid having a side chain diamine.

  Liquid crystal displays (LCDs) are displays that use photoelectric changes in liquid crystals, and have advantages such as small size, light weight, low power consumption, and excellent display quality. It has become.

  Liquid crystal displays are being twisted nematic (TN) and super twisted nematic (STN) liquid crystal displays in response to demands for increased screen size, high color saturation, high contrast, and improved response speed. From now on, it has been developed to a TFT liquid crystal display in which every pixel is provided with a thin film transistor (TFT). In recent years, driving methods for TFT-type liquid crystal displays have been continuously improved. For example, in the direction of viewing angle improvement, vertical alignment (VA) method and lateral electric field switching (IPS) method. Has been developed. Also, an OCB method (optically compensated band) that can improve the reaction speed corresponding to a moving image has been developed.

  A typical example of the liquid crystal display is a twisted nematic (TN) field effect liquid crystal display using a nematic liquid crystal having a positive dielectric anisotropy. In general, liquid crystal molecules are arranged between a pair of substrates having electrodes, the alignment directions of these two substrates are perpendicular to each other, and the alignment method of the liquid crystal molecules is controlled by controlling the electric field. Can do. What is important for this type of liquid crystal display is that the major axis direction of the liquid crystal molecules and the substrate surface are aligned at a uniform tilt angle. A material capable of aligning liquid crystal molecules with a uniform pre-tilt angle is generally referred to as an alignment film.

  Currently, there are two typical methods for preparing alignment films in the industry. The first method is a method of generating an inorganic substance into an inorganic film by vapor deposition. For example, when a thin film is formed by tilting vapor deposition of silica on a substrate, liquid crystal molecules are aligned in the vapor deposition direction. However, even if this method can obtain a uniform orientation, it does not produce much industrial effects and benefits. In the second method, after applying an organic film to the surface of the substrate, friction is applied using a soft cloth such as cotton, nylon or polyester, and the surface of the organic film is oriented to bring the liquid crystal molecules in the friction direction. It is a method of orienting. This method is relatively simple and can be applied very easily on an industrial scale because uniform orientation can be obtained very easily. Polymers that can form organic thin films are, for example, polyvinylalcohol (PVA), polyethylene oxide (PEO), polyamide (polyamide, PA) or polyimide, of which polyimide has chemical stability and thermal properties. Since it has properties such as stability, it is most often used as an alignment film material.

  However, when a voltage is applied to the liquid crystal display, the generated ionic charge is adsorbed on the liquid crystal alignment film, and even if the applied voltage is released, it is very difficult to release the ionic charge from the liquid crystal alignment film. Therefore, there arises a problem that an afterimage is generated on the screen. For this reason, recent developers of alignment film materials have made it a major challenge to improve the afterimage problem.

  An object of the present invention is to provide a liquid crystal aligning agent capable of obtaining a liquid crystal display device having a stable pretilt angle, excellent adhesion, and improved afterimage problems.

  The present invention provides a liquid crystal aligning agent comprising polymer (A) and polymer (B). The polymer (A) is a polyimide-polyamic acid having a side chain diamine represented by the following formula (1). The polymer (B) is a polyamic acid having a side chain diamine represented by the following formula (2). The weight ratio (A) / (B) of the polymer (A) and the polymer (B) is, for example, 5/95 to 95/5.

In formulas (1) and (2), T ₁ , T ₂ and T ₃ each represent a tetravalent organic group obtained from a tetracarboxylic dianhydride monomer, and n / (m + n) ≦ 0.5 And at least a part of D ₁ or D ₂ is selected from divalent organic groups obtained from the diamine compound represented by formula (3) or formula (4), and at least a part of D ₃ is is a divalent organic radical derived from a diamine compound represented by the formula (4), and other parts in the D _1, D ₂ and D ₃ is a divalent organic radical derived from a diamine compound.

In the formula (3), R ₁ , R ₂ , R ₃ , R ₅ and R ₆ each independently represent hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ₄ has 4 to 20 carbon atoms. An alkyl group, CO ₂ R ₂₂ , CON H R ₂₂ or (CH ₂ ) _p CF ₃ ; p is an integer of 1 to 5; R ₂₂ represents an alkyl group having 4 to 20 carbon atoms; In (4), any two of R _{7 to} R ₁₁ are primary amino groups, and the others are each independently a monovalent organic group other than a hydrogen atom or a primary amino group, and R _{7 to} R ₁₁ may be the same or different, and X ₁ and X ₂ are a single bond or a divalent linking group selected from the group consisting of ethers, ketones, esters, amides and secondary amines. are shown, X ₁ and X _2, which may be different from one another respectively the same, X ₃ and X _4, carbon atoms It indicates to 3 straight chain alkylene group, X ₃ and X _4, which may be different from one another respectively the same, R ₁₂ is an alkyl group having 1 to 20 carbon atoms, alicyclic having 3 to 40 carbon atoms A monovalent organic group having a cyclic skeleton, a monovalent organic group having an aromatic skeleton having 6 to 51 carbon atoms, or a monovalent organic group having a heterocyclic skeleton is shown.

According to the embodiment of the present invention, selected from divalent organic groups obtained from the diamine compound represented by the formula (3) or (4) in D ₁ , D ₂ and D ₃ of the liquid crystal aligning agent of the present invention. Except for the parts described above, the other parts in D ₁ , D ₂ and D ₃ described above may be selected from the group consisting of formulas (5) to (12).

Among them, R ₁₃ is an alicyclic monovalent organic group having 4 to 40 carbon atoms or a long-chain aliphatic monovalent organic group having 8 to 20 carbon atoms, and R ₁₄ is a halogen atom or a monovalent organic group. , R ₁₅ is an alicyclic divalent organic group having 4 to 40 carbon atoms, and R ₁₆ is a divalent alicyclic, divalent aromatic or long chain aliphatic divalent organic group having 1 to 8 carbon atoms. Wherein X and Y are each a divalent group selected from the group consisting of —O—, —NH—, —S—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—. And Z is selected from the group consisting of —CF ₃ , —CN, —COCH ₃ , —COOH, —NO ₂ , —SOCH ₃ , —SO ₂ CH ₃ , —OCF ₃ , —F and —Cl. It is a monovalent organic group.

According to the embodiment of the present invention, in the polymer (A), the content of the divalent organic group obtained from the diamine compound represented by the formula (3) is the divalent organic group D ₁ of the polymer (A). And the total amount of D ₂ is 0.1 mol% to 50 mol%.

According to the embodiment of the present invention, in the polymer (B), the content of the divalent organic group obtained from the diamine compound represented by the formula (3) is the divalent organic group D ₃ of the polymer (B). Is made 0.1 mol% to 50 mol%.

According to the embodiment of the present invention, in the polymer (A), the content of the divalent organic group obtained from the diamine compound represented by the formula (4) is the divalent organic group D ₁ of the polymer (A). And the total amount of D ₂ is 5 to 50 mol%.

According to the embodiment of the present invention, in the polymer (B), the content of the divalent organic group obtained from the diamine compound represented by the formula (4) is the divalent organic group D ₃ of the polymer (B). The total amount of is 5 mol% to 100 mol%.

  As described above, the present invention includes a polyimide-polyamic acid having a side chain diamine represented by the formula (1) and a polyamic acid having a side chain diamine represented by the formula (2) in the liquid crystal aligning agent. The liquid crystal alignment film formed by this liquid crystal alignment agent has a stable pretilt angle, improves the adhesion of the liquid crystal alignment film, and improves the afterimage problem. Can achieve the purpose.

  In order to make the above and other objects, features and advantages of the present invention more comprehensible, several embodiments accompanied with figures are described below.

  The liquid crystal aligning agent of this embodiment contains a polymer (A) and a polymer (B). The polymer (A) is a polyimide-polyamic acid having a side chain diamine represented by the following formula (1). The polymer (B) is a polyamic acid having a side chain diamine represented by the following formula (2).

In formula (1) and formula (2), T ₁ , T ₂ and T ₃ each represent a tetravalent organic group, n / (m + n) ≦ 0.5, and at least in D ₁ or D ₂ A part is selected from divalent organic groups obtained from the diamine compound represented by formula (3) or formula (4), and at least a part of D ₃ is a diamine compound represented by formula (4) The other part in D ₁ , D ₂ and D ₃ is a divalent organic group obtained from a diamine compound.

In the formula (3), R ₁ , R ₂ , R ₃ , R ₅ and R ₆ each independently represent hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ₄ has 4 to 20 carbon atoms. Represents an alkyl group, CO ₂ R ₂₂ , CON H R ₂₂ or (CH ₂ ) _p CF ₃ , p is an integer of 1 to 5, and R ₂₂ represents an alkyl group having 4 to 20 carbon atoms.

In Formula (4), any two of R _{7 to} R ₁₁ are primary amino groups, and the others are each independently a monovalent organic group other than a hydrogen atom or a primary amino group, R _{7 to} R ₁₁ may be the same or different, and X ₁ and X ₂ are a single bond or a divalent bond selected from the group consisting of ethers, ketones, esters, amides and secondary amines. X ₁ and X ₂ may be the same or different from each other, X ₃ and X ₄ represent a linear alkylene group having 1 to 3 carbon atoms, and X ₃ and X ₄ represent R ₁₂ may be the same as or different from each other, and R ₁₂ represents an alkyl group having 1 to 20 carbon atoms, a monovalent organic group having an alicyclic skeleton having 3 to 40 carbon atoms, and an aromatic group having 6 to 51 carbon atoms. 1 represents a monovalent organic group having a group skeleton or a monovalent organic group having a heterocyclic skeleton.

  The weight ratio (A) / (B) of the polymer (A) and the polymer (B) is, for example, 5/95 to 95/5.

Further, in D _1, D ₂ and D ₃ of the liquid crystal aligning agent of the present embodiment, the formula (3) or selected portions from divalent organic radical derived from a diamine compound represented by the formula (4), except The other parts in D ₁ , D ₂ and D ₃ described above may be selected from the group consisting of formulas (5) to (12).

Among them, R ₁₃ is an alicyclic monovalent organic group having 4 to 40 carbon atoms or a long-chain aliphatic monovalent organic group having 8 to 20 carbon atoms, and R ₁₄ is a halogen atom or a monovalent organic group. , R ₁₅ is an alicyclic divalent organic group having 4 to 40 carbon atoms, and R ₁₆ is a divalent alicyclic, divalent aromatic or long chain aliphatic divalent organic group having 1 to 8 carbon atoms. Wherein X and Y are each a divalent group selected from the group consisting of —O—, —NH—, —S—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—. And Z is selected from the group consisting of —CF ₃ , —CN, —COCH ₃ , —COOH, —NO ₂ , —SOCH ₃ , —SO ₂ CH ₃ , —OCF ₃ , —F and —Cl. It is a monovalent organic group.

  The method for preparing the polymer (A) synthesized by the present embodiment has a side chain diamine by subjecting a tetracarboxylic dianhydride and a diamine compound to a polymerization reaction in an organic solvent and a partial ring-closing reaction by a dehydration reaction. A polyimide-polyamic acid product is obtained.

  The tetracarboxylic dianhydride used for the synthesis of the polymer (A) can be selected from the compounds shown in Table 1. The diamine compound used for the synthesis of the polymer (A) can be selected from the diamine compounds represented by formula (3) and formula (4) shown in Table 2, and the formula (3) and It can also be selected from diamine compounds not represented by formula (4). At least one of the diamine compounds used for the synthesis of the polymer (A) is selected from the compounds shown in Table 2.

  Further, the tetracarboxylic dianhydride used for the synthesis of the polymer (A) of this embodiment may be an isomer of the compounds shown in Table 1 above, or a mixture of these isomers. Also good. The diamine compound used in the synthesis of the polymer (A) of the present embodiment may be an isomer of the compound shown in Table 2 or 3 above, or may be a mixture of these isomers. This embodiment is not limited only to the example mentioned above, The tetracarboxylic dianhydride and diamine compound to be used may be compounds other than the compound mentioned above.

  In particular, in order for the liquid crystal display element to have a high voltage holding ratio, NO. This can be achieved by selecting at least one of compounds having an alicyclic structure such as 1-2, 1-3, 1-4, 1-5, 1-6 and the like.

  Moreover, the pretilt angle of the liquid crystal in the liquid crystal aligning agent of this embodiment is adjusted by changing the size of the side chain on the polyimide-polyamic acid (for example, changing the size of the side chain group on the diamine compound). In Table 2, NO. By selecting at least one of the diamine compounds shown in 2-1 to 2-3, an appropriate pretilt angle can be provided. In addition, NO. By selecting at least one of the diamine compounds shown in 2-4 to 2-7, a liquid crystal aligning agent having excellent adhesion can be obtained.

  The method for preparing the polymer (B) synthesized by this embodiment is to obtain a polyamic acid product having a side chain diamine by polymerizing a tetracarboxylic dianhydride and a diamine compound in an organic solvent.

  The tetracarboxylic dianhydride used for the synthesis of the polymer (B) can be selected from the compounds shown in Table 1. The diamine compound used for the synthesis of the polymer (B) can be selected from the diamine compounds represented by formula (3) and formula (4) shown in Table 2, and the formula (3) and It can also be selected from diamine compounds not represented by formula (4). At least one of the diamine compounds used for the synthesis of the polymer (B) is NO. It is selected from the compounds shown in 2-4 to 2-7.

  Further, the tetracarboxylic dianhydride used for the synthesis of the polymer (B) of this embodiment may be an isomer of the compounds shown in Table 1 above, or a mixture of these isomers. Also good. The diamine compound used for the synthesis of the polymer (B) of the present embodiment may be an isomer of the compound shown in Table 2 or 3 above, or may be a mixture of these isomers. This embodiment is not limited only to the example mentioned above, The tetracarboxylic dianhydride and diamine compound to be used may be compounds other than the compound mentioned above.

The divalent organic group represented by the formula (3) has a stable pretilt angle, and makes the liquid crystal display element have a stable alignment effect. In the polymer (A), the content of the divalent organic group obtained from the diamine compound represented by the formula (3) is such that the total amount of the divalent organic groups D ₁ and D ₂ of the polymer (A) is 0.1. It is preferable to set it as mol%-50 mol%. In the polymer (B), the content of the divalent organic group obtained from the diamine compound represented by the formula (3) is 0.1 mol% to the total amount of the divalent organic group D ₃ of the polymer (B). It is preferably 50 mol%.

The divalent organic group represented by the formula (4) has a stable pretilt angle, and makes the liquid crystal display element have a stable alignment effect. In the polymer (A), the content of the divalent organic group obtained from the diamine compound represented by (4) is 5 mol% to the total amount of the divalent organic groups D ₁ and D ₂ of the polymer (A). It is preferably 50 mol%. In the polymer (B), the content of the divalent organic group obtained from the diamine compound represented by the formula (4) is 5 mol% to 100 mol based on the total amount of the divalent organic group D ₃ of the polymer (B). % Is preferable.

  The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polymer (A) of the present embodiment is such that the content of the acid anhydride group of the tetracarboxylic dianhydride is 1 equivalent, and the amino group of the diamine compound. The content of is preferably 0.5 equivalents to 2 equivalents, and more preferably the content of amino groups of the diamine compound is 0.7 equivalents to 1.5 equivalents.

  In the synthesis of the polymer (A), the reaction is completed in an organic solvent, but the organic solvent to be used is an organic solvent having a relatively high solubility in polyimide-polyamic acid and a relatively low solubility in polyimide-polyamic acid. Divided into organic solvents. Organic solvents having a relatively high solubility in polyimide-polyamic acid include, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylcaprolactam, dimethyl sulfoxide, tetramethylurea, Examples of the solvent include γ-butyrolactone and pyridine. Two or more of the above solvents may be used in combination.

  An organic solvent having a relatively low solubility in polyimide-polyamic acid may be used by mixing with an organic solvent having a relatively high solubility in polyimide-polyamic acid as described above, but it is used that polyimide-polyamic acid is not separated. Limit. Solvents with relatively low solubility include methylol, ethanol, isopropoxide, n-butanol, cyclohexanol, ethylene glycol, ethylene glycol methyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl Includes ether, diethyl ether, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, tetrahydrofuran, dichloromethane, trichloromethane, 1,2-dichloroethane, benzene, ethyl toluene, diethyl toluene, hexane, n-heptane, n-octane, etc. It is.

  In order to form the polymer (A), it is necessary to perform a dehydration ring-closing reaction. The dehydration ring closure reaction may be carried out by direct heat dehydration ring closure or by adding a dehydrating agent and a catalyst.

(1) Direct heating dehydration ring closure:
The reaction temperature is, for example, between 50 ° C and 300 ° C, and preferably between 100 ° C and 250 ° C. When the reaction temperature is lower than 50 ° C., the dehydration ring closure reaction does not proceed.

(2) Add dehydrating agent and catalyst:
The reaction temperature is, for example, between −20 ° C. and 150 ° C., and preferably between 0 ° C. and 120 ° C. Examples of the dehydrating agent that can be used include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride. The dose of the dehydrating agent is determined in view of the necessary ring closure rate, but it is preferable to use 0.01 to 20 mol of the dehydrating agent for each 1 mol of the polyimide-polyamic acid reproducible unit. As the catalyst, for example, a tertiary amine such as triethylamine, pyridine, dimethylpyridine and the like can be used. The catalyst is preferably used in an amount of 0.01 mol to 10 mol per 1 mol of dehydrating agent.

  In the purification method of the polymer (A), first, a polyimide-polyamic acid reaction solvent is poured into a solvent having a relatively low solubility to obtain a precipitate. Then, polyimide-polyamic acid can be obtained by drying under reduced pressure. Thereafter, the polyimide-polyamic acid is dissolved in an organic solvent, and precipitation is performed with a solvent having a relatively low solubility. This step can be performed once or multiple times to purify the polyimide-polyamic acid. Finally, the polyimide-polyamic acid after performing the above-described steps with a solvent having a relatively high solubility is dissolved to obtain a purified polymer (A).

The viscosity (η _ln ) of the liquid crystal aligning agent of the present embodiment is obtained by Expression (I).

  The liquid crystal aligning agent of this embodiment preferably has a solid content selected on the basis of viscosity and volatility of 1 wt% to 10 wt%.

  A liquid crystal aligning film is formed by applying the liquid crystal aligning agent of this embodiment on a substrate to form a film. When the solid content of the liquid crystal aligning agent is lower than 1% by weight, the thickness of the alignment film to be applied becomes excessively thin, so that the liquid crystal alignment is lowered. When the solid content of the liquid crystal aligning agent is higher than 10% by weight, the coating quality is not affected.

  Moreover, it is preferable that the temperature which prepares the liquid crystal aligning agent of this embodiment is 0 to 150 degreeC, More preferably, it is 20 to 50 degreeC.

  Examples of the organic solvent for the liquid crystal aligning agent of the present embodiment include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylcaprolactam, dimethyl sulfoxide, γ-butyrolactone, and γ-butyrolactam. , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol monobutyl ether, and the like, and the above-mentioned solvents may be used as a mixture of two or more. Other than the above-described solvents, any organic solvent that can dissolve the polyimide-polyamic acid can be used.

  Examples of the liquid crystal aligning agent of the present embodiment include aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinylmethylsilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2 -Aminoethyl) -3-aminopropyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-epoxypropyloxypropyltrimethoxysilane, 3-epoxypropyloxypropylmethyldimethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-carbamidopropyltrimethoxysilane, 3-carbamidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropi Triethoxysilane, N-triethoxymethylsilanepropyltriethylenetriamine, N-trimethoxymethylsilanepropyltriethylenetriamine, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene)- An organic siloxane compound such as 3-aminopropyltriethoxysilane may also be included. Adhesion of the liquid crystal alignment film to the substrate surface can be improved under the condition that the above-described organosiloxane compound does not affect the characteristics required of the liquid crystal alignment film in the content in the liquid crystal alignment agent. When the content of the organosiloxane compound in the liquid crystal aligning agent is too large, the liquid crystal alignment film to be formed easily causes a phenomenon of poor alignment. If the content of the organosiloxane compound in the liquid crystal aligning agent is too small, the liquid crystal aligning film to be formed causes a phenomenon of rubbing mura or excessive particles. Therefore, when the liquid crystal aligning agent of this embodiment contains an organic siloxane compound, the concentration of the organic siloxane compound is 0.01% by weight to 5% by weight with respect to the polymer in the liquid crystal aligning agent. Preferably, it is 0.1 to 3% by weight.

  Furthermore, the liquid crystal aligning agent of this embodiment is also, for example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexane glycol diglycidyl ether. Glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexane glycol, N, N, N ′, N′-tetraglycidyl-m -Phenylxylene, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl-4,4-diaminodiphenylmethyl, 3- (N-allyl-N -Glycidyl) aminopropyltrimethoxysilane, 3- (N, An epoxy compound such as N-diglycidyl) aminopropyltrimethoxysilane may also be included. The adhesiveness of the liquid crystal alignment film to the substrate surface can be improved under the condition that the above-described epoxy compound does not affect the characteristics required of the liquid crystal alignment film in the content in the liquid crystal alignment agent. If the content of the epoxy compound in the liquid crystal aligning agent is too large, the formed liquid crystal alignment film easily causes a phenomenon of alignment failure. If the content of the epoxy compound in the liquid crystal aligning agent is too small, the formed liquid crystal alignment film causes a phenomenon of poor friction and excessive grinding. Therefore, when the liquid crystal aligning agent of this embodiment contains an epoxy compound, it is preferable that the density | concentration of an epoxy compound is 0.01 weight%-3 weight% with respect to the total weight of a liquid crystal aligning agent, More preferably Is 0.1 wt% to 2 wt%.

  Below, the liquid crystal display panel manufactured using the liquid crystal aligning agent of this embodiment is demonstrated. The liquid crystal display panel can be manufactured by the following steps.

  (1) The liquid crystal aligning agent of this embodiment is applied on a glass substrate by a roller coating method, a spin coating method, or a printing coating method. This glass substrate has a patterned transparent conductive film. After applying the liquid crystal aligning agent, heat baking is performed to remove the organic solvent in the liquid crystal aligning agent, and the polyamic acid that has not been cyclized is promoted to undergo a dehydration / ring-closing reaction to form a polyimide thin film. The temperature of the heating baking described above is between 80 ° C and 300 ° C, and most preferably between 100 ° C and 240 ° C. The thickness of the thin film formed is most preferably 0.005 μm to 0.5 μm.

  (2) The formed thin film is subjected to frictional orientation with a roller in which a nylon or cotton fabric is wound, so that the liquid crystal molecules have orientation.

  (3) A sealant is applied on the substrate having the liquid crystal alignment film described above, and a gap material is sprayed on the other substrate having the liquid crystal alignment film, and then the two substrates are perpendicular to the friction direction of each other. Alternatively, they are combined in parallel, and liquid crystal is injected into the gap between the two substrates to seal the injection hole, thereby forming a liquid crystal display panel.

  For liquid crystal display elements, the following characteristics are usually used as evaluation indices:

(1) Pretilt angle A liquid crystal display panel filled with liquid crystal is measured by a crystal rotation method.

(2) Measurement of change in pretilt angle Nine points are measured in the liquid crystal box, and the difference between the maximum value and the minimum value is evaluated as the change degree. The smaller the degree of change in the pretilt angle, the better the stability.

(3) Voltage holding ratio A voltage of 3 V is applied to a liquid crystal display element 60 Hz and a pulse width 60 μsec at an environmental temperature of 90 ° C. to measure the voltage holding ratio of the liquid crystal display element.

(4) Determination of Afterimage Phenomenon First, the transmittance and voltage change at a specific position of the liquid crystal display element are measured with a voltage applied. The liquid crystal display element is charged with DC power of 30 V for 2 hours and then discharged for a certain time. Thereafter, the transmittance and the amount of voltage change are measured at the same position. Using a voltage with a transmittance of 50% as a reference, the amount of change before and after the transmittance at the reference voltage is measured, and further divided by the original transmittance and displayed as a percentage. A case where the amount of change before and after the transmittance is <5% is determined to be excellent, a case where it is> 5% is determined to be medium, and a case where it is greater than 10% is determined to be inferior.

(4) Cyclization rate (imidation rate)
The polymer or liquid crystal aligning agent is dried under reduced pressure at room temperature, and the dried solid is dissolved in deuterated dimethyl sulfoxide. Tetramethylsilane is used as a reference substance, measured by ¹ H-NMR, and the imidization ratio is obtained from Formula (II).

[Equation 2]
Imidization rate (%) = (1-A ¹ / A ² × α) × 100 (II)

A ¹ : Peak area derived from NH group protons (10 ppm)
A ² : Peak area derived from other protons α: Quantity ratio of other protons to one proton of NH group in polymer precursor (polyamic acid)

(5) Adhesiveness A liquid crystal aligning agent is apply | coated on an ITO board | substrate, and an ITO board | substrate is boiled at 100 degreeC for 1 hour, Then, a cross cut method (cross cut method) is performed with a 3m adhesive tape.

  Below, the synthesis | combining method of polymer A1-A7, B1-B6 and a1, b1-b3 is demonstrated.

  A diamine compound and tetracarboxylic dianhydride are sequentially added to N-methyl-2-pyrrolidone (the ratio is as shown in Tables 4 and 5) to produce a solution having a solid content of 25% by weight. The polyamic acid was obtained by reacting at a temperature of from 60 to 60 ° C. for 4 to 5 hours. In polyamic acid obtained by adding pyridine and acetic anhydride (dose is always added based on the ratio of polyimide formation), dehydration / ring-closure reaction was performed at 100 to 110 ° C. for 3 to 4 hours. The resulting solution was precipitated using methanol and purified with methanol. Finally, the polymer was collected and dried under reduced pressure to obtain polymers A1 to A7, B1 to B6 and a1, b1 to b3 having intrinsic viscosity and polyimide ratio shown in Tables 4 and 5. Among them, a1 and b1 to b3 do not include the diamine compound represented by Formula (3) and Formula (4).

[Experimental methods of Examples and Controls]
The solid polymer (A) and the solid polymer (B) having a fixed ratio were dissolved in a mixed solvent of γ-butyrolactone and N-methyl-2-pyrrolidone to produce a solution having a solid component of 6% by weight, and having a diameter of 1 μm. It filtered with the filter. The collected filtrate is the liquid crystal aligning agent of this embodiment.

  The liquid crystal aligning agent of this embodiment was applied on the glass substrate with the roller printer, and it dried with the heating plate whose temperature is 200 degreeC for 20 minutes, and formed the thin film with a thickness of 0.08 micrometer. This thin film was subjected to orientation friction at a roller rotation speed of 1000 (rotation / min), a plate moving speed of 60 (mm / sec), and a penetration depth of 0.4 μm.

  A sealant was applied on the substrate and the interstitial material was sprayed on the other substrate. Thereafter, the two substrates were combined perpendicularly or parallel to the direction of friction with each other, and liquid crystal (ZLI-4792) was injected into the gap between the two substrates to seal the injection hole, thereby forming a liquid crystal display element.

  The obtained liquid crystal display element was evaluated for pretilt angle, voltage holding ratio, afterimage characteristics, and adhesion. The evaluation results are as shown in Table 6.

  As described above, this embodiment includes a polyimide-polyamic acid having a side chain diamine represented by the formula (1) and a polyamic acid having a side chain diamine represented by the formula (2) in the liquid crystal aligning agent. Accordingly, the liquid crystal alignment film formed by this liquid crystal alignment agent has a stable pretilt angle, improves the adhesion and friction of the liquid crystal alignment film, and further improves the afterimage problem. The purpose of improving the function of the display element can be achieved.

  As described above, the present invention has been disclosed by the embodiments. However, the present invention is not intended to limit the present invention, and is within the scope of the technical idea of the present invention so that those skilled in the art can easily understand. Since such changes and modifications can be made naturally, the scope of patent protection must be defined on the basis of the scope of claims and a uniform area thereof.

Claims (6)

A polymer (A) which is a polyimide-polyamic acid having a side chain diamine represented by the formula (1);
A polymer (B) which is a polyamic acid having a side chain diamine represented by the formula (2), and the weight ratio (A) / (B) of the polymer (A) to the polymer (B) is 5 / A liquid crystal aligning agent that is 95 to 95/5,

In formula (1) and formula (2), T ₁ , T ₂ and T ₃ are each a tetravalent organic group, n / (m + n) ≦ 0.5, and D ₁ , D ₂ and D ₃ Is a divalent organic group, and at least a part of D ₁ or D ₂ is selected from divalent organic groups obtained from a diamine monomer represented by formula (3) or formula (4), and D ₃ At least a part thereof is a divalent organic group obtained from a diamine monomer represented by the formula (4),

In formula (3), R ₁ , R ₂ , R ₃ , R ₅ and R ₆ each independently represent hydrogen or an alkyl group having 1 to 5 carbon atoms, and R ₄ has ₄ to 20 carbon atoms. Represents an alkyl group, CO ₂ R ₂₂ , CON H R ₂₂ or (CH ₂ ) _p CF ₃ , p is an integer of 1 to 5, R ₂₂ represents an alkyl group having 4 to 20 carbon atoms,

In the formula (4), any two of R _{7 to} R ₁₁ are primary amino groups, and the others are each independently a monovalent organic group other than a hydrogen atom or a primary amino group, and R _{7 to} R ₁₁ may be the same or different and each of X ₁ and X ₂ is a single bond or a divalent linking group selected from the group consisting of ethers, ketones, esters, amides and secondary amines. X ₁ and X ₂ may be the same or different from each other, X ₃ and X ₄ represent a linear alkylene group having 1 to 3 carbon atoms, and X ₃ and X ₄ are Each may be the same or different, and R ₁₂ is an alkyl group having 1 to 20 carbon atoms, a monovalent organic group having an alicyclic skeleton having 3 to 40 carbon atoms, or an aromatic group having 6 to 51 carbon atoms. Liquid crystal alignment showing a monovalent organic group having a skeleton or a monovalent organic group having a heterocyclic skeleton Agent. The portion not selected from the divalent organic group obtained from the diamine monomer represented by the formula (3) or the formula (4) in the D ₁ and D ₂ is represented by the formula (5) to the formula (12). Selected from the group consisting of
The portion not selected from the divalent organic group obtained from the diamine monomer represented by formula (4) in D ₃ is selected from the group consisting of formula (5) to formula (12). ,

Among them, R ₁₃ is an alicyclic monovalent organic group having 4 to 40 carbon atoms or a long-chain aliphatic monovalent organic group having 8 to 20 carbon atoms, and R ₁₄ is a halogen atom or a monovalent organic group. R ₁₅ is an alicyclic divalent organic group having 4 to 40 carbon atoms, and R ₁₆ is a divalent alicyclic, divalent aromatic or long chain aliphatic divalent organic group having 1 to 8 carbon atoms. Wherein X and Y are each selected from the group consisting of —O—, —NH—, —S—, —CO—, —COO—, —OCO—, —NHCO—, —CONH—. A group wherein Z is selected from the group consisting of —CF ₃ , —CN, COCH ₃ , —COOH, —NO ₂ , SOCH ₃ , —SO ₂ CH ₃ , —OCF ₃ , —F and —Cl; The liquid crystal aligning agent according to claim 1 which is a valent organic group. In the polymer (A), the content of the divalent organic group obtained from the diamine monomer represented by the formula (3) is such that the total amount of the divalent organic groups D ₁ and D ₂ of the polymer (A) is 0. The liquid crystal aligning agent of Claim 1 or 2 made into 1 mol%-50 mol%. In the polymer (B), the content of the divalent organic group obtained from the diamine monomer represented by the formula (3) is 0.1 mol of the total amount of the divalent organic group D ₃ of the polymer (B). The liquid crystal aligning agent of any one of Claim 1 to 3 made into%-50 mol%. In the polymer (A), the content of the divalent organic group obtained from the diamine compound represented by the formula (4) is 5 as the total amount of the divalent organic groups D ₁ and D ₂ of the polymer (A). The liquid crystal aligning agent of any one of Claim 1 to 4 made it mol%-50 mol%. In the polymer (B), Formula (4) content of divalent organic radical derived from a diamine compound represented by the polymer (B) 5 mol% to 100 the total amount of divalent organic radical D ₃ having the The liquid crystal aligning agent of any one of Claim 1 to 5 made into mol%.