TWI726965B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element for an alignment film for optical alignment that does not produce bright spots even if it is a negative liquid crystal and can obtain good residual image characteristics.

A liquid crystal alignment agent, which is characterized in that it contains a polyimide precursor having a structural unit represented by formula (1) and a structural unit represented by formula (2), and the polyimide precursor of the polyimide precursor At least one polymer (A) selected from the group of aminated polymers.

式中之記號的定義，係如說明書中所記載之內容。

The definition of the symbol in the formula is as stated in the specification.

Description

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

The present invention relates to a liquid crystal alignment agent suitable for photo-alignment processing, a liquid crystal alignment film obtained using the liquid crystal alignment agent, and a liquid crystal display element obtained using the liquid crystal alignment film.

Liquid crystal display elements used in liquid crystal televisions, liquid crystal displays, etc. usually control the arrangement state of liquid crystals, etc., and a liquid crystal alignment film is provided in the elements. The liquid crystal alignment film mainly uses a liquid crystal alignment agent mainly composed of polyimide precursors such as polyimide (polyimide) or a solution of soluble polyimide, coated on a glass substrate, etc., and then fired. A polyimide-based liquid crystal alignment film prepared by baking. At present, the most popular method in the industry is that the liquid crystal alignment film uses cloth such as cotton, nylon, polyester, etc., to wipe the surface of the polyimide-based liquid crystal alignment film formed on the electrode substrate in one direction, which is called rubbing. Manufactured by the way of processing.

The photo-alignment method is an alignment treatment method that does not require rubbing, and has the advantage that it can be produced in an industrially simple manufacturing process. Therefore, it is a liquid crystal display element that is driven by an IPS driving method or a wide viewing angle opening and closing (hereinafter, FFS) driving method. Among them, the use of the liquid crystal alignment film obtained by the photo-alignment method, when compared with the liquid crystal alignment film obtained by the rubbing treatment method, can improve the liquid crystal display due to the expected improvement of the contrast of the liquid crystal display element or the improvement of the viewing angle characteristics. The performance of the device has attracted attention for its excellent liquid crystal alignment processing method.

However, the liquid crystal alignment film obtained according to the optical alignment method still has the problem of less anisotropy to the alignment direction of the polymer film when compared with the rubbing process. When the anisotropy is small, sufficient liquid crystal alignment cannot be obtained, and when used as a liquid crystal display element, problems such as afterimages may occur. To improve the anisotropy of the liquid crystal alignment film obtained by the photo-alignment method, there have been proposals to remove the low molecular weight component generated by the light irradiation to cut the main chain of the polyimide after light irradiation.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-297313

[Patent Document 2] JP 2011-107266 A

[Non-Patent Literature]

[Non-Patent Document 1] "Liquid Crystal Optical Alignment Film" Kidowaki, Ichimura Functional Materials November 1997 Issue Vol.17 No.11 Pages 13-22

In the liquid crystal display element of the IPS driving method or the FFS driving method, the positive type liquid crystal has been used in the past, but when the negative type liquid crystal is used, the penetration loss at the top of the electrode can be reduced, and the contrast can be improved. When using the liquid crystal display element of the IPS driving method or FFS driving method of the liquid crystal alignment film obtained by the photo-alignment method and the negative liquid crystal, it can be expected to have higher display performance than the conventional liquid crystal display element.

However, the inventors of the present case have studied the results and learned that the liquid crystal alignment film obtained by photo-alignment will have a higher incidence of poor display (bright spots) when using liquid crystal display elements of negative liquid crystals, which will cause display failures. Good and other issues.

The object of the present invention is to provide a liquid crystal alignment agent suitable for photo-alignment treatment, which does not produce bright spots even when negative liquid crystals are used, and can obtain good residual image characteristics for the liquid crystal alignment film used in the photo-alignment method. A liquid crystal alignment film derived from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment agent.

As a result of intensive research, the inventors found that when a liquid crystal alignment agent containing a polyimide-based polymer with a specific structure is effective for achieving the above-mentioned object, and thus completed the present invention.

The gist of the present invention is as described below.

1. A liquid crystal alignment agent, characterized in that it contains a polyimide precursor having a structural unit represented by the following formula (1) and the following formula (2) and the polyimide precursor of the polyimide precursor At least one polymer (A) selected from the group of aminated polymers.

(In formula (1) and formula (2), X ₁ and X ₂ each independently represent a tetravalent organic group, R ₁ and R ₂ each independently represent a hydrogen atom, or an alkyl group with 1 to 4 carbon atoms, A ₁ , A ₂ , A ₃ , and A ₄ each independently represent a hydrogen atom or an alkyl group with 1 to 4 carbon atoms, and Z ₁ , Z ₂ , Z ₃ , and Z ₄ each independently represent a hydrogen atom, a halogen atom, and a carbon number of 1 ~4 alkyl group, n is an integer of 1~4).

According to the content of the present invention, it is possible to provide a liquid crystal alignment film that can suppress the bright spots caused by the photo-alignment treatment method even when a negative type liquid crystal is used, and can produce a liquid crystal alignment film with high irradiation sensitivity and good after-image characteristics. A liquid crystal alignment agent suitable for photo-alignment processing. When the liquid crystal alignment film obtained from the liquid crystal alignment agent is provided, a liquid crystal display element with no display defects and high reliability can be provided.

[The form of implementing the invention] <Specific polymer>

The liquid crystal alignment agent of the present invention, as described above, contains a polyimide precursor having the structural unit represented by the above formula (1) and the above formula (2), and the polyimide precursor of the polyimide precursor At least one polymer selected from the group of aminated polymers (also referred to as specific polymer (A)).

In formula (1) and formula (2), R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. From the viewpoint of easy imidization by heating, a hydrogen atom or a methyl group is particularly preferred. X ₁ and X ₂ are tetravalent organic groups. It is preferably a structure that can be decomposed or isomerized by ultraviolet radiation, and imparts anisotropy. The group is composed of the structures represented by the following formulas (X1-1)~(X1-9) At least one selected is preferred.

In formula (X1-1), R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbons, an alkenyl group with 2 to 6 carbons, and alkynyl group , Or phenyl, which can be the same or different. From the viewpoint of liquid crystal alignment, R ₃ , R ₄ , R ₅ , and R _{6 are} preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and a hydrogen atom or a methyl group is more preferable. The specific structure of the formula (X1-1) includes, for example, the structures represented by the following formulas (X1-10) to (X1-11). From the viewpoint of liquid crystal orientation and sensitivity, (X1-11) is particularly preferred.

In formula (1) and formula (2), A ₁ , A ₂ , A ₃ , and A ₄ each independently represent a hydrogen atom or an alkyl group with 1 to 4 carbon atoms. From the viewpoint of the orientation of the liquid crystal, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is preferred.

In formula (1) and formula (2), Z ₁ , Z ₂ , Z ₃ , and Z ₄ each independently represent a hydrogen atom, a halogen atom, or an alkyl group with 1 to 4 carbon atoms. From the viewpoint of the orientation of the liquid crystal, a hydrogen atom, a halogen atom, or a methyl group is preferred. n is an integer from 1 to 4.

In the specific polymer (A), from the viewpoint of liquid crystal alignment and suppression of bright spots, the ratio of the structural unit represented by the above formula (1) relative to 1 mol of the total structural unit is preferably 10-50 mol% , More preferably 30-50 mol%.

In addition, in the specific polymer (A), the content ratio of the structural unit represented by the above formula (2), from the viewpoint of liquid crystal orientation and suppression of bright spots, is 20 to 90 mol relative to 1 mol of the total structural unit % Is better, more preferably 20-50 mol%.

For the specific polymer (A), from the viewpoint of the mechanical strength of the alignment film, in addition to the structural unit represented by the above formulas (1) and (2), it is preferable to have the structural unit represented by the following formula (3) .

In the formula (3), X ₃ , including its preferred examples, has the same meaning as _{X 1} and X ₂ in the above formulas (1) and (2). R ₃ , including its preferred examples, has the same meaning _{as the above-mentioned R 1} and R _2. Y ₁ is at least one selected from the group of structures represented by the following formulas [1d-1] to [1d-7].

In the above formula [1d-1] to formula [1d-7], D is a tert-butoxymethoxycarbonyl group. n ₁ to n ₅ each independently represent an integer of 1 to 5.

More specific examples of Y ₁ include the following formulas [1d1-1] to [1d1-6] and the like.

In the above [1d1-1] to [1d1-6], D is tert-butoxymethoxycarbonyl.

The content ratio of the structural unit represented by the formula (3) is preferably 10-50 mol%, and more preferably 20-30 mol% relative to 1 mol of the entire structural unit of the specific polymer (A).

The specific polymer (A), in addition to the structural units represented by the above formulas (1) to (3), may further have a polyimide precursor containing the structural unit represented by the following formula (4) and the polyimide Precursor of imine.

In the formula (4), R ₄ , including its preferred examples, has the same meaning as _{R 1} in the above formula (1). A ₅ and A ₆ , including their preferred examples, have the same meaning as _{A 1} and A _{2 of the above formula (1).} X is a tetravalent organic group, and its structure is not particularly limited.

When specific examples are given, for example, the above-mentioned formulas (X1-1) to (X1-9) or the following formulas (X-9) to (X-42), etc. can be mentioned. In terms of easy access to compounds, X can be exemplified by X1-1~X1-9, X-17, X-25, X-26, X-27, X-28, X-32, or X-39. In addition, from the viewpoint of the use of direct current voltage to ease the accumulated residual charge and to obtain an early liquid crystal alignment film, tetracarboxylic dianhydride having an aromatic ring structure is preferred. X is X-26, X-27, X -28, X-32, X-35, or X-37 is preferred.

In the above formula (4), Y is a divalent organic group, and its structure is not particularly limited. When specific examples of Y ₂ are given, for example, the following formulas (Y-1) to (Y-84) and the like can be mentioned.

For the purpose of improving the orientation of the liquid crystal, Y is preferably a structure with high linearity. For example, Y-7, Y-43~Y-48, Y63, or Y-71~Y-76 are preferred. From the viewpoint of using DC voltage to alleviate the accumulated residual charge, and to obtain the liquid crystal alignment film at an early stage, Y-77~Y-84 are preferred.

<Manufacturing method of polyamide ester>

The polyimide precursor of the polyimide used in the present invention can be synthesized according to the method (1), (2) or (3) shown below.

(1) Synthesis of polyamide acid

Polyamide ester can be synthesized by esterification of polyamide acid obtained from tetracarboxylic dianhydride and diamine.

Specifically, for example, the polyamide acid and the esterification agent can be carried out 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, it can be synthesized by reacting for 1 to 4 hours.

-2-基)-4-甲基嗎啉鎓氯化物等。酯化劑之使用量，相對於聚醯胺酸之重複單位1莫耳，以2~6莫耳當量為佳。 The esterification agent is preferably one that can be easily removed through purification, such as N,N-dimethylformamide dimethyl acetal, N,N-dimethylformamide diethyl acetal Aldehydes, N,N-dimethylformamide dipropyl acetal, N,N-dimethylformamide dineopentylbutyl acetal, N,N-dimethylformamide bis-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-tri

-2-yl)-4-methylmorpholinium chloride and the like. The amount of esterification agent used is preferably 2-6 mol equivalents relative to 1 mol of the repeating unit of polyamide acid.

The solvent used in the above reaction is preferably N,N-dimethylformamide, n-methyl-2-pyrrolidone, or γ-butyrolactone in terms of polymer solubility. One type or two or more types can be used. The concentration at the time of synthesis is not easy to cause the precipitation of the polymer, and it is easy to obtain the high molecular polymer. From the viewpoint of 1-30% by mass, 5-20% by mass is more preferable.

(2) When reacting tetracarboxylic acid diester dichloride with amine

Polyurethane can be synthesized from tetracarboxylic acid diester dichloride and diamine.

Specifically, for example, the tetracarboxylic acid diester dichloride and diamine in the presence of a base and an organic solvent are carried out at -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes It can be synthesized by reaction for ~24 hours, preferably 1~4 hours.

As the aforementioned base, pyridine, triethylamine, 4-dimethylaminopyridine, etc. can be used, but when the reaction can proceed stably, pyridine is preferably used. From the viewpoint that the amount of alkali added can be easily removed and the polymer can be easily prepared, it is better to use 2 to 4 times moles of tetracarboxylic acid diester dichloride.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone from the viewpoint of the solubility of monomers and polymers. One or more of these can be used. Either way. In terms of the polymer concentration during synthesis, it is not easy to cause the precipitation of the polymer, and it is easy to prepare the polymer, preferably 1-30% by mass, and more preferably 5-20% by mass. In addition, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used in the synthesis of polyamide esters should preferably be dehydrated as much as possible, and should be used in a nitrogen atmosphere to prevent external air. .

(3) Reaction of tetracarboxylic acid diester and diamine

Polyurethane can be synthesized by polycondensation of tetracarboxylic acid diester and diamine.

Specifically, for example, the tetracarboxylic acid diester and the diamine in the presence of a condensing agent, a base, and an organic solvent are carried out at 0°C to 150°C, preferably 0°C to 100°C, for 30 minutes It can be synthesized by reaction for ~24 hours, preferably 3~15 hours.

甲基嗎啉鎓、O-(苯併三唑-1-基)-N,N,N’,N’-四甲基脲四氟硼酸鹽、O-(苯併三唑-1-基)-N,N,N’,N’-四甲基脲六氟磷酸鹽、(2,3-二氫-2-硫氧雜-3-苯併噁唑基)膦酸(phosphoric acid)二苯酯等。縮合劑之添加量，相對於四羧酸二酯以2~3倍莫耳為佳。 As the aforementioned condensing agent, triphenyl phosphite, dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N, N'-carbonyl diimidazole, dimethoxy-1,3,5-tri

Methylmorpholinium, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethylurea tetrafluoroborate, O-(benzotriazol-1-yl) -N,N,N',N'-tetramethylurea hexafluorophosphate, (2,3-dihydro-2-thioxa-3-benzoxazolyl)phosphoric acid diphenyl Ester etc. The amount of condensing agent added is preferably 2 to 3 times the molar ratio of the tetracarboxylic acid diester.

Among the aforementioned bases, tertiary amines such as pyridine and triethylamine can also be used. The amount of alkali added can be easily removed, and from the viewpoint of obtaining a high polymer easily, it is better to use 2 to 4 times moles relative to the diamine component.

In addition, in the above reaction, when Lewis acid is added as an additive, the reaction can be made to proceed efficiently. Lewis acid is preferably lithium halides such as lithium chloride and lithium bromide. The amount of Lewis acid added is preferably 0~1.0 times mole relative to the diamine component.

Among the above three synthetic methods of polyamide esters, from the viewpoint that high-molecular-weight polyamide esters can be obtained, the synthesis method of the above-mentioned (1) or the above-mentioned (2) is particularly preferred.

The polyamide ester solution obtained according to the above method can be poured into a poor solvent with sufficient stirring to precipitate the polymer. After several times of precipitation, washing with a poor solvent, and drying at room temperature or by heating, a refined polyamide powder can be obtained. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, cellosolve (cellosolve), acetone, and toluene.

<Manufacturing method of polyamide acid>

The polyimide precursor of the polyimide used in the present invention can be synthesized according to the method shown below.

Specifically, for example, tetracarboxylic dianhydride and diamine in the presence of an organic solvent are carried out at -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes to 24 hours. Preferably, it can be synthesized in a reaction mode of 1-12 hours.

For the organic solvent used in the above reaction, in terms of the solubility of monomers and polymers, N,N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone Preferably, one or more of these can be used. The concentration of the polymer is not easy to cause the precipitation of the polymer, and it is easy to obtain a polymer from the viewpoint of preferably 1-30% by mass, and more preferably 5-20% by mass.

The polyamide acid prepared in the above manner can be used to precipitate and recover the polymer by injecting the reaction solution into a poor solvent while fully stirring. In addition, after several times of precipitation, washing with a poor solvent, and drying at room temperature or by heating, a purified polyamide acid powder can be obtained. Examples of poor solvents include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Manufacturing Method of Polyimide>

The polyimide used in the present invention can be prepared by imidizing the aforementioned polyamide ester or polyamide acid. When producing polyimide from polyamide, add alkaline amine to the polyamide solution described above or the polyamide acid solution obtained by dissolving polyamide resin powder in an organic solvent. The chemical imidization of the medium is a simple method. For chemical imidization, the imidization reaction can be carried out at a relatively low temperature, and it is preferred that it does not cause a decrease in the molecular weight of the polymer during the imidization process.

Chemical imidization is performed by stirring the polyamide to be imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, the solvent used in the aforementioned polymerization reaction can be used. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, in order to allow triethylamine to react, it is preferable to maintain sufficient alkalinity.

The temperature for carrying out the imidization reaction is -20°C to 140°C, preferably 0°C to 100°C, and the reaction time is preferably 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mole times of the amide acid ester group, preferably 2 to 20 mole times. The imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time. In the solution after the imidization reaction, the added catalyst will remain in the solution, so the resulting imidized polymer can be recovered by the following methods and re-dissolved in an organic solvent as a liquid crystal The alignment agent users are better.

In the case of producing polyimide from polyamic acid, it is simple to add a catalyst to the solution of polyimide obtained by reacting the diamine component with tetracarboxylic dianhydride. method. For chemical imidization, the imidization reaction can be carried out at a relatively low temperature. It is preferable that the molecular weight of the polymer is not easily reduced during the imidization process.

Chemical imidization can be carried out by stirring the polymer to be imidized in the presence of a basic catalyst and acid anhydride in an organic solvent. As the organic solvent, the solvent used in the aforementioned polymerization reaction can be used. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, in order to allow pyridine to react, it is preferable to have an appropriate basicity. Moreover, the acid anhydride can be exemplified by acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, when acetic anhydride is used, it is easier to purify after the reaction is completed.

The temperature during the imidization reaction is -20°C to 140°C, preferably 0°C to 100°C, and the reaction time can be carried out in 1 to 100 hours. The amount of alkaline catalyst is 0.5 to 30 mol times of the amide acid group, preferably 2 to 20 mol times, and the amount of acid anhydride is 1 to 50 mol times of the amide acid group, preferably 3 to 30 mol times. The imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.

In the solution after the imidization reaction of polyamide or polyamide acid, the added catalyst will remain. Therefore, the obtained imidization polymer can be recovered by the following means to make it Re-dissolved in an organic solvent is preferred as the liquid crystal alignment agent of the present invention.

The polyimide solution obtained in the above manner is poured into a poor solvent with sufficient stirring, and the polymer can be precipitated. After several times of precipitation, washing with a poor solvent, and drying at room temperature or by heating, a purified polyamide powder can be obtained.

The aforementioned 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 alignment agent>

The liquid crystal alignment agent used in the present invention has a solution form obtained by dissolving the specific polymer (A) in an organic solvent. The molecular weight of the specific polymer (A) preferably has a weight average molecular weight of 2,000 to 500,000, more preferably 5,000 to 300,000, and more preferably 10,000 to 100,000. In addition, the number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and more preferably 5,000 to 50,000.

The concentration of the polymer in the liquid crystal alignment agent can be appropriately changed according to the thickness of the coating film to be formed, but when a uniform and defect-free coating film is formed, 1% by weight or more is preferred, and the solution is stored In terms of stability, 10% by weight or less is preferable.

The solvent used in the liquid crystal alignment agent of the present invention is not particularly limited as long as it is a solvent (also referred to as a good solvent) that can dissolve the specific polymer (A). The following are specific examples of good solvents.

For example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl methacrylate Suspension, γ-butyrolactone, 1,3-dimethyl-imidazolinone, methyl ethyl ketone, cyclohexanone, cyclopentanone or 4-hydroxy-4-methyl-2-pentanone, etc. Among them, it is preferable to use N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and γ-butyrolactone.

In addition, from the viewpoint of improving the solubility of the specific polymer (A) in a solvent, the solvent represented by the following formula [D-1] to formula [D-3] is preferred.

In formula [D-1] ~ formula [D-3], D ¹ represents an alkyl group with 1 to 3 carbons, D ² represents an alkyl group with 1 to 3 carbons, and D ³ represents an alkyl group with 1 to 4 carbons ).

In the liquid crystal alignment agent, the content of the good solvent is preferably 20 to 99% by mass of the total solvent, preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass.

The liquid crystal alignment agent may contain a solvent (also called a poor solvent) that can improve the coating property or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied. These poor solvents are preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent, preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass.

The following are specific examples of poor solvents.

Ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, Isoamyl alcohol, tert-pentanol, 3-methyl-2-butanol, neopentanol, 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-methyl Cyclohexanol, 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- Pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene two Alcohol 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 acetic acid Ester, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, ethylene 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-(butoxy Ethoxy) 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 acetic acid Ester, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene two Alcohol monobutyl ether acetate, 2-(2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylenedi Alcohol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate , Ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid propyl ester, 3 -Butyl methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate or the aforementioned formula [D-1] to formula [D-3].

Among them, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether or dipropylene glycol dimethyl ether are preferred.

In the liquid crystal alignment agent of the present invention, a cross-linking compound having an epoxy group, an isocyanate group, an oxetane group or a cyclocarbonate group is introduced, and it is composed of a hydroxyl group, a hydroxyalkyl group and a lower alkoxyalkyl group. A crosslinkable compound with at least one substituent selected in a group, or a crosslinkable compound with a polymerizable unsaturated bond is preferable. These substituents or polymerizable unsaturated bonds must have two or more in the crosslinkable compound.

Crosslinkable compounds with epoxy groups or isocyanate groups, for example, bisphenol acetone glycidyl ether, phenol-novolac epoxy resin, cresol-novolac epoxy resin, triglycidyl isocyanurate , Tetraglycidylamino diphenyl ester, tetraglycidyl-m-xylene diamine, tetraglycidyl-1,3-bis(aminoethyl)cyclohexane, tetraphenylglycidyl ether ethane, three Phenyl glycidyl ether ethane, bisphenol hexafluoroacetic acid diglycidyl ether, 1,3-bis(1-(2,3-glycidyloxy)-1-trifluoromethyl-2,2,2 -Trifluoromethyl)benzene, 4,4-bis(2,3-glycidoxy)octylfluorobiphenyl, triglycidyl-p-aminophenol, tetraglycidyl methylxylene diamine, 2 -(4-(2,3-glycidoxy)phenyl)-2-(4-(1,1-bis(4-(2,3-glycidoxy)phenyl)ethyl) Phenyl) propane or 1,3-bis(4-(1-(4-(2,3-epoxypropoxy)phenyl)-1-(4-(1-(4-(2,3- Glycidyloxy)phenyl)-1-methylethyl)phenyl)ethyl)phenoxy)-2-propanol and the like.

The crosslinkable compound having an oxetane group includes, for example, a compound having at least two oxetane group represented by the following formula [4A].

Specifically, for example, the crosslinkable compound shown by formula [4a]~formula [4k] etc. which are disclosed on page 58-59 of International Publication WO2011/132751 (2011.10.27 publication).

The crosslinkable compound having a cyclocarbonate group includes, for example, a crosslinkable compound having at least two cyclocarbonate groups represented by the following formula [5A].

Specifically, for example, the cross-linking compound shown in formula [5-1] to formula [5-42] disclosed on pages 76 to 82 of International Publication No. WO2012/014898 (2012.2.2 publication), etc. .

樹脂、乙炔脲-甲醛樹脂、琥珀醯胺-甲醛樹脂或乙烯脲-甲醛樹脂等。具體而言，可列舉如，可使用胺基中之氫原子被羥甲基或烷氧甲基或該二者所取代之三聚氰胺衍生物、苯併呱

衍生物，或乙炔脲。該三聚氰胺衍生物或苯併呱

衍生物，可 以2聚物或3聚物形式存在。該些以每一三

環，平均具有3個以上6個以下之羥甲基或烷氧甲基者為佳。 A crosslinkable compound having at least one substituent selected from the group consisting of a hydroxyl group and an alkoxy group, for example, an amine-based resin having a hydroxyl group or an alkoxy group, for example, melamine resin, urea resin, and

Resin, acetylene urea-formaldehyde resin, succinamide-formaldehyde resin or ethylene urea-formaldehyde resin, etc. Specifically, for example, a melamine derivative, benzoxan, in which the hydrogen atom in the amino group is replaced by a methylol group, an alkoxymethyl group, or both, can be used.

Derivatives, or acetylene carbamide. The melamine derivative or benzodiazepine

Derivatives can exist in the form of 2-mer or 3-mer. Every three

The ring preferably has 3 or more and 6 or less hydroxymethyl or alkoxymethyl groups on average.

衍生物之例如，市售品之每一個三

環平均具有3.7個甲氧甲基取代之MX-750、每一個三

環平均具有5.8個甲氧甲基取代之MW-30(以上，三和化學公司製)或CYMEL-300、301、303、350、370、771、325、327、703、712等之甲氧甲基化三聚氰胺、CYMEL-235、236、238、212、253、254等之甲氧甲基化丁氧甲基化三聚氰胺、CYMEL-506、508等之丁氧甲基化三聚氰胺、CYMEL-1141等含羧基之甲氧甲基化異丁氧甲基化三聚氰胺、CYMEL-1123等甲氧甲基化乙氧甲基化苯併呱

、CYMEL-1123-10等甲氧甲基化丁氧甲基化苯併呱

、CYMEL-1128等丁氧甲基化苯併呱

、CYMEL-1125-80等含羧基之甲氧甲基化乙氧甲基化苯併呱

(以上，三井氰胺公司製)等。 The above-mentioned melamine derivatives or benzodiazepines

For example of derivatives, each of the three commercially available products

The ring has an average of 3.7 methoxymethyl substituted MX-750, each with three

MW-30 (above, manufactured by Sanwa Chemical Co., Ltd.) or CYMEL-300, 301, 303, 350, 370, 771, 325, 327, 703, 712, etc., with an average ring having 5.8 methoxymethyl substitutions Alkylated melamine, CYMEL-235, 236, 238, 212, 253, 254, etc., butoxymethylated butoxymethylated melamine, CYMEL-506, 508, etc., butoxymethylated melamine, CYMEL-1141, etc. Methoxymethylated isobutoxymethylated melamine, CYMEL-1123 of carboxyl group, methoxymethylated ethoxymethylated benzoquat

, CYMEL-1123-10 and other methoxymethylated butoxymethylated benzoquat

, CYMEL-1128 and other butoxymethylated benzogua

, CYMEL-1125-80 and other carboxyl-containing methoxymethylated ethoxymethylated benzoquat

(Above, manufactured by Mitsui Cyanamide) etc.

Also, examples of acetylene carbamide include butoxymethylated acetylene carbamide such as CYMEL-1170, methylolated acetylene carbamide such as CYMEL-1172, etc., and methoxymethylated acetylene carbamide such as POWERLINK-1174.

Benzene or phenolic compounds with hydroxyl or alkoxy groups, for example, 1,3,5-gins(methoxymethyl)benzene, 1,2,4-gins(isopropoxymethyl)benzene, 1,4- Bis(sec-butoxymethyl)benzene or 2,6-dimethylol-p-tert-butanol, etc.

More specifically, for example, crosslinkable compounds of formula [6-1] to formula [6-48] disclosed on pages 62 to 66 of International Publication No. WO2011/132751 (published on October 27, 2011).

Crosslinkable compounds with polymerizable unsaturated bonds, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, tri(meth)acrylate Base) acryloxy ethoxy trimethylol propane or glycerol polyglycidyl ether poly(meth)acrylate and other cross-linking compounds with 3 polymerizable unsaturated groups in the molecule, another example is ethylene glycol Di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth) Acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide bisphenol A type di(meth)acrylic acid Ester, propylene oxide bisphenol type di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerol di(meth)acrylate, pentaerythritol di(meth)acrylic acid Ester, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ether di(meth)acrylate or hydroxyl new Crosslinkable compounds with two polymerizable unsaturated groups in the molecule such as neopentyl glycol di(meth)acrylate, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (Meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-(meth)acryloyloxy-2- Hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerol mono(meth)acrylate, 2-(meth)acryloyloxyethyl phosphate or Crosslinkable compounds having one polymerizable unsaturated group in the molecule, such as N-hydroxymethyl (meth)acrylamide.

In addition, a compound represented by the following formula [7A] can also be used.

(In formula [7A], E ₁ represents a group selected from the group consisting of cyclohexane ring, bicyclohexane ring, benzene ring, biphenyl ring, terphenyl ring, naphthalene ring, sulphur ring, anthracene ring or phenanthrene ring _{E 2} represents the group selected by the following formula [7a] or formula [7b], and n represents an integer of 1 to 4).

The above is an example of a crosslinkable compound, but it is not limited to these contents. In addition, the crosslinkable compound used for the liquid crystal alignment agent may be used in one type, or may be used in combination of two or more types.

The content of the crosslinking compound in the liquid crystal alignment agent is preferably 0.1 to 150 parts by mass relative to 100 parts by mass of the total polymer components. Among them, from the viewpoint of producing the desired effect due to the cross-linking reaction, it is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of the total polymer components. More preferably, it is 1-50 parts by mass.

The liquid crystal alignment agent of the present invention can be a compound that can improve the film thickness uniformity or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied.

Compounds that improve the film thickness uniformity or surface smoothness of the liquid crystal alignment film include, for example, fluorine-based surfactants, polysiloxane-based surfactants, and nonionic surfactants.

More specifically, for example, F-Top EF301, EF303, EF352 (above, manufactured by Dow Chemical Co., Ltd.), Megaface F171, F173, R-30 (above, manufactured by Dainippon Paint Co., Ltd.), FLUORAD FC430, FC431 (Above, manufactured by Sumitomo 3M), AsahiGuard AG710, SurflonS-382, SC101, SC102, SC103, SC104, SC105, SC106 (above, manufactured by Asahi Glass), etc.

The usage amount of the surfactant is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass relative to 100 parts by mass of all polymer components contained in the liquid crystal alignment agent.

In addition, the liquid crystal alignment agent can also be added with a compound that promotes the movement of charges in the liquid crystal alignment film and removes the charge of the device. For example, it is disclosed in International Publication No. WO2011/132751 (2011.10.27 publication), pages 69~73 The nitrogen represented by the formula [M1]~the formula [M156] contains a heterocyclic amine compound. The amine compound can be directly added to the liquid crystal alignment agent, but it is preferably added in a solution with a concentration of 0.1-10% by mass, preferably 1-7% by mass. The solvent is not particularly limited as long as it can dissolve the specific polymer (A).

In the liquid crystal alignment agent of the present invention, in addition to the above-mentioned poor solvents, cross-linking compounds, compounds that can improve the uniformity or surface smoothness of the resin film or liquid crystal alignment film, and compounds that promote the removal of charges, as long as it does not damage Within the scope of the effect of the present invention, a polymer other than the polymer described in the present invention can be added to improve the adhesion between the alignment film and the substrate as a silane coupling agent, and even when the baked film is fired, it can effectively promote the transfer The polyimide precursor is heated to carry out the imidization of the imidization accelerator and the like.

<Liquid crystal alignment film, liquid crystal display element>

The liquid crystal alignment film is a film obtained by coating the above-mentioned liquid crystal alignment agent on a substrate, drying and baking. The substrate on which the liquid crystal alignment agent of the present invention can be coated is not particularly limited as long as it is a substrate with high transparency. In addition to glass substrates and silicon nitride substrates, acrylic substrates or polycarbonate substrates can be used. The plastic substrate and so on. In this case, when using a substrate formed with ITO electrodes and the like used for the purpose of driving liquid crystals, it is preferable from the viewpoint of simplification of the manufacturing process. In addition, when the reflective liquid crystal display element is only a single-sided substrate, an opaque material such as a silicon wafer can also be used. In this case, an electrode that can reflect light such as aluminum can also be used.

The coating method of the liquid crystal alignment agent is not particularly limited. Industrially, methods such as screen printing, offset printing, Flexo printing, or inkjet methods are generally used. Other coating methods include, for example, a dipping method, a roll coating method, a slit coating method, a spin coater method, or a spray method. These methods can be used according to the purpose.

After the liquid crystal alignment agent is coated on the substrate, the liquid crystal alignment film can be formed after the solvent is evaporated by heating means such as a heating plate, a thermal cycle oven or an IR (infrared) oven. In the drying and baking steps after coating the liquid crystal alignment agent of the present invention, any temperature and time can be selected. Usually, for example, the calcination is performed at 50 to 120°C for 1 to 10 minutes by fully removing the contained solvent, and then the calcination is performed at 150 to 300°C for 5 to 120 minutes. If the thickness of the sintered liquid crystal alignment film is too thin, the reliability of the liquid crystal display element may be reduced. Therefore, 5~300nm is better, and 10~200nm is better.

Although the rubbing treatment method can be used for the method of aligning the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention, the photo-alignment treatment method is more preferable. A preferred example of the photo-alignment treatment method is to irradiate the surface of the aforementioned liquid crystal alignment film with radiation deviated in a certain direction. Depending on the situation, it is preferable to perform a heat treatment at a temperature of 150 to 250°C to impart liquid crystal alignment ( Also known as liquid crystal alignment capability) method and so on. For the radiation, ultraviolet or visible light with a wavelength of 100~800nm can be used. Among them, it is preferably an ultraviolet ray having a wavelength of 100 to 400 nm, and more preferably a wavelength of 200 to 400 nm.

In addition, from the viewpoint of improving the alignment of the liquid crystal, the substrate coated with the liquid crystal alignment film can also be heated to 50-250°C and irradiated with radiation. In addition, the irradiation amount of the aforementioned radiation is preferably 1 to 10,000 mJ/cm ^{2 and more} preferably 100 to 5,000 mJ/cm ² . The liquid crystal alignment film obtained by this can make the liquid crystal molecules align in a certain direction stably.

As the extinction ratio of polarized ultraviolet rays is higher, higher anisotropy can be imparted, which is better. Specifically, for example, the extinction ratio of linearly polarized ultraviolet rays is preferably 10:1 or more, and more preferably 20:1 or more.

In addition, in the aforementioned method, the liquid crystal alignment film irradiated with polarized radiation may also be subjected to contact treatment using water or a solvent.

The solvent used in the above-mentioned contact treatment is not particularly limited as long as it can dissolve the decomposition products generated by the liquid crystal alignment film due to irradiation of radiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve ( cellosolve), ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate or cyclohexyl acetate, etc. Among them, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate are preferred from the viewpoint of universality or solvent safety, and water, 1-methoxy-2-propanol is preferred. Alcohol or ethyl lactate is preferred. One type or a combination of two or more types of solvents can be used.

The above-mentioned contact treatment, that is, for example, the treatment of water or solvent applied to the liquid crystal alignment film irradiated with polarized radiation, for example, immersion treatment or spray treatment (Spray treatment). The time required for these treatments can effectively dissolve the decomposition products generated by the liquid crystal alignment film caused by the radiation. 10 seconds to 1 hour is preferable, and the immersion treatment is performed for 1 minute to 30 minutes. The one is better. In addition, the solvent used in the contact treatment may be at room temperature or heated, and it is preferably 10 to 80°C. Among them, 20~50℃ is better. In addition, from the viewpoint of the solubility of the decomposed product, it can be combined with the necessary name, ultrasonic treatment, etc. can also be performed.

After the aforementioned contact treatment, it is better to use a low-boiling solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone for washing (also referred to as "washing") or for baking the liquid crystal alignment film. At this time, either washing or roasting may be performed, or both may be performed. The baking temperature is preferably 150-300°C, preferably 180-250°C, and particularly preferably 200-230°C. The baking time is preferably 10 seconds to 30 minutes, preferably 1 to 10 minutes.

The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film of a liquid crystal display element of a transverse electric field method such as an IPS method or an FFS method, and is particularly suitable for use in a liquid crystal display element of the FFS method. After the liquid crystal display element is prepared with a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, a known method can be used to fabricate a liquid crystal cell, and the liquid crystal cell can be used.

An example of a method for manufacturing a liquid crystal cell will be explained by taking a liquid crystal display element with a passive element matrix structure as an example. In addition, each pixel portion constituting the displayed image may be a liquid crystal display element of an active matrix structure provided with switching elements such as TFT (Thin Film Transistor).

Specifically, for example, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. For these electrodes, for example, ITO electrodes can be formed, and the desired patterning of the displayed image can be performed. Secondly, on each substrate, an insulating film covering the common electrode and the segment electrode can be provided. The insulating film may be, for example, a SiO ₂ -TiO ₂ film formed by a sol-gel method.

Secondly, a liquid crystal alignment film is formed on each substrate, and the one side substrate and the other side substrate are superimposed with the liquid crystal alignment film surface facing each other, and the periphery is bonded with a sealant. When the sealant is used to control the gap between the substrates, it can usually be mixed into the spacers. In addition, it is better to spread the spacers used to control the gap between the substrates in the surface where the sealant is not provided. A part of the sealant is provided with an opening that can be filled with liquid crystal from the outside.

Next, the 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 the adhesive. The injection method can be a vacuum injection method, and a capillary phenomenon can also be used in the atmosphere. The liquid crystal material may be either a positive type liquid crystal material or a negative type liquid crystal material, preferably a negative type liquid crystal material. Secondly, set up the polarizer. Specifically, for example, a pair of polarizing plates can be attached to the surfaces of the two substrates on the opposite side of the liquid crystal layer.

As described above, when the liquid crystal alignment agent of the present invention is used, a liquid crystal alignment film can be obtained that has the ability to suppress the residual image caused by AC driving and has the adhesion of the sealant and the underlying substrate. In particular, it is useful for the liquid crystal alignment film used in the photo-alignment treatment method of irradiating polarized radiation.

[Example]

Examples will be listed below to illustrate the present invention in more detail, but the present invention is not limited by these explanations.

The following are the abbreviations of the compounds used and the measurement methods.

NMP: N-methyl-2-pyrrolidone, BCS: butyl cellosolve (cellosolve)

DA-1: 1,2-bis(4-aminophenoxy)ethane

DA-2: 1,3-bis(4-aminophenoxy)propane

DA-3: p-phenylenediamine

DA-6: 4-(2-(methylamino)ethyl)aniline

[Viscosity]

The viscosity of the polyamic acid ester and polyamic acid solution uses the E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), with a sample volume of 1.1 mL, Conerotar TE-1 (1°34', R24), and temperature Measured at 25°C.

[Molecular Weight]

The molecular weight of polyamide ester is measured by using a GPC (normal temperature gel permeation chromatography) device, and the number average molecular weight (hereinafter, also referred to as Mn) and weight are calculated based on the conversion value of polyethylene glycol and polyethylene oxide Average molecular weight (hereinafter also referred to as Mw).

GPC device: manufactured by Shodex Corporation (GPC-101)

Column: manufactured by Shodex (KD803, KD805 in-line)

Column temperature: 50℃

Eluent: N,N-dimethylformamide (additives are lithium bromide-hydrate (LiBr‧H ₂ O) 30mmol/L, phosphoric acid‧anhydrous crystal (o-phosphoric acid) 30mmol/L, tetrahydrofuran (THF) 10ml/L)

Flow rate: 1.0ml/min

Standard sample for making calibration line: TSK standard polyethylene oxide manufactured by Tosoh Corporation (weight average molecular weight (Mw) approximately 900,000, 150,000, 100,000, 30,000), and polyethylene glycol manufactured by Polymer Research Institute Co., Ltd. (wave peak The molecular weight (Mp) is about 12,000, 4,000, 1,000). In the measurement, in order to avoid overlapping of the peaks, the four types of samples, including 900,000, 100,000, 12,000, and 1,000, and the three types of samples, including 150,000, 30,000, and 4,000, are mixed.

[Determination of imidization rate]

5(草野科學製))中，添加重氫化二甲基亞碸(DMSO-d6，0.05% TMS(四甲基矽烷)混合品)(0.53ml)，施以超音波使其完全溶解。使用NMR測定機(JNW-ECA500)(日本電子數據製)測定該溶液中之500MHz之質子NMR。醯亞胺化率，為由醯亞胺化前後未產生變化的結構所產生之質子作為基準質子所決定，為使用該質子的波峰積算值，與出現於9.5ppm~10.0ppm附近的醯胺酸之由NH基產生之質子波峰積算值，依以下計算式而求得者。 Add 20mg of polyimide powder into NMR sample tube (NMR sample standard tube,

5 (made by Kusano Science)), add deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53ml), and apply ultrasonic waves to completely dissolve it. The 500 MHz proton NMR in the solution was measured using an NMR measuring machine (JNW-ECA500) (manufactured by JEOL Ltd.). The rate of imidization is determined by the protons produced by the unchanging structure before and after imidization as the reference protons. It is the peak integration value of the protons and is compared with the imidic acid that appears near 9.5 ppm to 10.0 ppm. The proton peak product value generated by the NH group can be obtained according to the following formula.

The imidization rate (%)=(1-α‧x/y)×100

In the above formula, x is the peak product value of protons generated by the NH group of the amide acid, y is the peak product value of the reference proton, and α is the polyamide acid (the imidization rate is 0%). The ratio of the number of standard protons relative to one NH proton of amic acid.

[Anisotropy of Alignment Film]

The measurement was performed using the liquid crystal alignment film evaluation system "Rey‧ScanLab H" (LYS-LH30S-1A) manufactured by Moritex. A polyimide film with a film thickness of 100 nm was irradiated with ultraviolet rays through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained alignment film was measured.

[Production of liquid crystal cell]

Fabricate a liquid crystal cell with the composition content of a Fringe Field Switching (FFS) mode liquid crystal display element.

First, prepare a substrate with electrodes. It is formed on a glass substrate with a length of 30 mm, a width of 0 mm, and a thickness of 0.7 mm to form an ITO electrode with a solid pattern pattern that constitutes the counter electrode as the first layer. The second layer on the counter electrode as the first layer is a SiN (silicon nitride) film formed by a CVD method. The SiN film of the second layer has a thickness of 500 nm and functions as an interlayer insulating film. On the second layer of SiN film, there are arranged as the third layer as an ITO film, a dentate-shaped pixel electrode formed by patterning (patterning) to form two pixels: a first pixel and a second pixel Pixel. The size of each pixel is 10mm in length and 5mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are formed to be electrically insulated through the action of the SiN film of the second layer.

The pixel electrode of the third layer has a tooth-like shape composed of a plurality of electrode elements in the shape of "ㄑ" in which the central part of the arrangement is bent. The width of each electrode element in the short-side direction is 3 μm, and the interval between the electrode elements is 6 μm. The pixel electrode forming each pixel is composed of a plurality of electrode elements with a curved "ㄑ" shape at the center of the arrangement. Therefore, the shape of each pixel is not rectangular, but is the same as the electrode element. The central part is a flexed shape similar to the bold "ㄑ". Therefore, each pixel is divided into upper and lower regions with the flexion part at the center as the boundary, and has a first area above the flexion part and a second area below the flexion part.

When the first area and the second area of each pixel are compared, they are those whose formation directions of the electrode elements constituting the pixel electrode are different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, in the first area of the pixel, the electrode element of the pixel electrode forms an angle of +10° (clockwise), and the second area of the pixel is drawn The electrode elements of the element electrode form an angle of -10° (clockwise). That is, in the first area and the second area of each pixel, the liquid crystal caused by the application of a voltage between the pixel electrode and the counter electrode has a direction of rotation (plane ‧ opening and closing) in the surface of the substrate. They are in opposite directions to each other.

Next, after filtering the obtained liquid crystal alignment agent with a 1.0μm filter, it was coated on the prepared substrate with electrodes and the glass with column spacers having a height of 4μm with an ITO film formed on the inner surface using a spin coater. Substrate. After drying on a hot plate at 80°C for 5 minutes, it is fired in a hot air circulating oven at 230°C for 20 minutes to form a coating film with a thickness of 100nm. The coating film surface is irradiated with ultraviolet rays with a wavelength of 254 nm using linearly polarized light with an extinction ratio of 10:1 or more through a polarizing plate. The substrate is immersed in at least one type of solvent selected from water and organic solvents for 3 minutes, then immersed in pure water for 1 minute, and heated on a hot plate at 150°C to 300°C for 5 minutes to obtain liquid crystal alignment. The substrate of the film. Take the above two substrates as a set, print a sealant on the substrate, and stick the other substrate facing the liquid crystal alignment film surface with the alignment direction at 0°, and then harden the sealant to produce an empty cell . After the liquid crystal MLC-7026-100 (manufactured by Mork Co., Ltd.) was injected into the empty cell by a reduced pressure injection method, the injection port was sealed to obtain an FFS driven liquid crystal cell. Subsequently, the obtained liquid crystal cell was heated at 110° C. for 1 hour, and after being left overnight, it was used for each evaluation.

[Evaluation of residual image caused by long-term AC drive]

A liquid crystal cell having the same structure as the liquid crystal cell used in the above-mentioned residual image evaluation was prepared.

In a constant temperature environment of 60°C, the liquid crystal cell is subjected to an alternating voltage of ±5V with a frequency of 60 Hz for 120 hours. Subsequently, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left at room temperature for one day.

After placement, the liquid crystal cell is placed between the two polarizing plates arranged in a vertical cross mode with the polarization axis, and the backlight is turned on under no applied voltage, and the arrangement angle of the liquid crystal cell is adjusted to transmit light The brightness reaches the minimum state. Subsequently, the angle of rotation from the darkest angle in the second area of the first pixel to the darkest angle in the first area is calculated, and the rotation angle generated when the liquid crystal cell rotates is calculated as the angle Δ. The same is true for the second pixel. After comparing the second area with the first area, the angle Δ is calculated in the same way.

[Evaluation of the bright spots of liquid crystal cells (comparison)]

The bright spots of the liquid crystal cells prepared above were evaluated. The bright spot evaluation of the liquid crystal cell was performed by observing the liquid crystal cell using a polarizing microscope (ECLIPSE E600WPOL) (manufactured by Nikon). Specifically, for example, you can observe the liquid crystal cell with a polarizing microscope with a magnification of up to 5 times and set up a beam, and calculate the number of bright spots that can be confirmed. If the number of bright spots is less than 10, it is marked as "good". Those above are marked as "bad".

<Synthesis Example 1>

In a 50mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA-1 0.81g (3.30mmol), DA-2 0.57g (2.20mmol), DA-3 0.36g (3.30mmol), DA- 4 0.88g (2.20mmol), add 29.99g of NMP, and stir to dissolve in nitrogen gas. While stirring the diamine solution, add 2.35 g (10.51 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 6.40 g of NMP to make it solid The component concentration reached 12% by mass, and the mixture was stirred at room temperature for 24 hours to prepare a polyamide acid solution (A). The viscosity of the polyamide acid solution at a temperature of 25°C was 316mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=13230 and Mw=29550.

<Synthesis example 2>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh DA-1 0.54g (2.20mmol), DA-2 0.85g (3.30mmol), DA-3 0.36g (3.30mmol), DA- 4 0.88 g (2.20 mmol), 30.17 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring the diamine solution, add 2.35 g (10.51 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, and then add 6.34 g of NMP to make it solid The concentration reached 12% by mass, and the mixture was stirred at room temperature for 24 hours to prepare a polyamide acid solution (B). The viscosity of the polyamic acid solution at a temperature of 25°C was 356mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=14,120 and Mw=31,210.

<Synthesis Example 3>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh DA-1 0.88g (3.60mmol), DA-2 0.31g (1.20mmol), DA-3 0.52g (4.80mmol), DA- 4 0.96 g (2.40 mmol), 30.64 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring the diamine solution, add 2.57 g (11.46 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, and then add 7.74 g of NMP to make the solid content concentration It reached 12% by mass and stirred at room temperature for 24 hours to prepare a polyamide acid solution (C). The viscosity of the polyamide acid solution at a temperature of 25°C was 336mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=13410 and Mw=30110.

<Synthesis Example 4>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh DA-1 0.54g (2.20mmol), DA-2 0.57g (2.20mmol), DA-3 0.48g (4.40mmol), DA- 4 0.88 g (2.20 mmol), 28.27 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring the diamine solution, add 2.35g (10.51mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 7.03g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (D). The viscosity of the polyamide acid solution at a temperature of 25°C was 366mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=14530 and Mw=36150.

<Synthesis Example 5>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh DA-1 0.95g (3.90mmol), DA-2 0.67g (2.60mmol), DA-3 0.70g (6.50mmol), and add NMP 26.76g, stirred in nitrogen gas to dissolve. While stirring the diamine solution, add 2.78g (12.42mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 10.71g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (E). The viscosity of the polyamide acid solution at a temperature of 25°C was 301mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=11990 and Mw=25310.

<Synthesis Example 6>

In a 50mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA-1 0.81g (3.30mmol), DA-2 0.57g (2.20mmol), DA-3 0.36g (3.30mmol), DA- 5 0.75 g (2.20 mmol), 28.55 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring the diamine solution, add 2.35g (10.51mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 6.93g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (F). The viscosity of the polyamide acid solution at a temperature of 25°C is 350mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=15220 and Mw=31850.

<Synthesis Example 7>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh DA-1 0.88g (3.60mmol), DA-3 0.65g (6.00mmol), DA-4 0.96g (2.40mmol), and add NMP 28.57g, stirred in nitrogen gas to dissolve. While stirring the diamine solution, add 2.57g (11.46mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 8.49g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (G). The viscosity of the polyamide acid solution at a temperature of 25°C was 386mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=16530 and Mw=37220.

<Synthesis Example 8>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh 1.59g (6.50mmol) of DA-1 and 0.70g (6.50mmol) of DA-3, add 26.34g of NMP, and stir under nitrogen. , Make it dissolve. While stirring the diamine solution, add 2.78g (12.42mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 10.86g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (H). The viscosity of the polyamic acid solution at a temperature of 25°C was 310mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=13310 and Mw=26210.

<Synthesis Example 9>

In a 50mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh 1.68g (6.50mmol) of DA-2 and 0.70g (6.50mmol) of DA-3, add 27.39g of NMP, and stir under nitrogen , Make it dissolve. While stirring the diamine solution, add 2.78g (12.42mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 10.48g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (I). The viscosity of the polyamic acid solution at a temperature of 25°C was 322mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=14430 and Mw=29950.

<Synthesis Example 10>

In a 50mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh DA-3 1.46g (13.50mmol) and DA-6 0.36g (1.50mmol), add 20.88g of NMP, and stir under nitrogen , Make it dissolve. While stirring the diamine solution, add 3.21g (14.33mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 15.98g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (J). The viscosity of the polyamic acid solution at a temperature of 25°C was 344mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=14430 and Mw=34850.

<Synthesis Example 11>

In a 50 mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh 2.69 g (11.00 mmol) of DA-1, add 30.90 g of NMP, and stir in the nitrogen gas to dissolve it. While stirring the diamine solution, add 2.35g (10.51mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and then add 6.07g of NMP to make the solid content concentration reach 12% by mass, and stirred at room temperature for 24 hours to prepare a polyamide acid solution (K). The viscosity of the polyamic acid solution at a temperature of 25°C was 367mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=17110 and Mw=33310.

<Example 1>

In a 100ml Erlenmeyer flask, weigh 15.00g of the 12% by mass polyamide acid solution (A) obtained in Synthesis Example 1, add 9.00g of NMP and 6.00g of BCS, and mix at 25°C for 8 hours to prepare a liquid crystal alignment agent (1). No abnormal phenomena such as turbidity or precipitation were found in the liquid crystal alignment agent, and it was confirmed that it was a uniform solution.

<Examples 2~6>

Except for using the 12% by mass polyamide acid solutions (B) to (F) obtained in Synthesis Examples 2 to 6, everything else was implemented in the same manner as in Example 1, and liquid crystal alignment agents (2) to ( 6). Among these liquid crystal alignment agents, no abnormal phenomena such as turbidity or precipitation were found, and it was confirmed that it was a uniform solution.

<Comparative Examples 1 to 5>

Except for using the 12% by mass polyamide acid solutions (G) to (K) obtained in Synthesis Examples 7 to 11, the others were implemented in the same manner as in Example 1, to obtain a liquid crystal alignment agent (7) to (11). Among these liquid crystal alignment agents, no abnormal phenomena such as turbidity or precipitation were found, and it was confirmed that it was a uniform solution.

(Example 7)

After filtering the liquid crystal alignment agent (1) obtained in Example 1 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation was 100 / cm ² of different anisotropy value 1.31,150mJ / cm ² of different anisotropy value 3.10,200mJ / cm ² of different tropism is 2.25. The irradiation amount of the above-mentioned ultraviolet rays that can obtain the highest anisotropy is 150 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment treatment.

(Example 8)

After filtering the liquid crystal alignment agent (2) obtained in Example 2 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation is 50mJ / cm ² of different anisotropy value 0.43,100mJ / cm ² of different anisotropy value 3.53,150mJ / cm ² of Time anisotropy value of 3.26. The irradiation amount of the above-mentioned ultraviolet rays that can obtain the highest anisotropy is 150 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment treatment.

(Example 9)

After filtering the liquid crystal alignment agent (3) obtained in Example 3 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 200mJ / cm ² of different anisotropy value 2.24,300mJ / cm ² of different anisotropy value 3.41,400mJ / cm ² of different tropism is 1.51. The irradiation amount of the above-mentioned ultraviolet rays, which can obtain the highest anisotropy, is 300 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment treatment.

(Example 10)

After filtering the liquid crystal alignment agent (4) obtained in Example 4 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of different anisotropy value 1.15,200mJ / cm ² of different anisotropy value 2.30,300mJ / cm ² of Time anisotropy value of 2.26. The irradiation amount of the above-mentioned ultraviolet rays, which can obtain the highest anisotropy, is 200 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment treatment.

(Example 11)

After filtering the liquid crystal alignment agent (5) obtained in Example 5 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of different anisotropy value 4.29,150mJ / cm ² of Time anisotropy value 5.23,200mJ / cm ² of different tropism is 3.00. The irradiation amount of the above-mentioned ultraviolet rays that can obtain the highest anisotropy is 150 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment treatment.

(Example 12)

After filtering the liquid crystal alignment agent (6) obtained in Example 6 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of Time anisotropy value 2.76,150mJ / cm ² of different anisotropy value 4.87,200mJ / cm ² of different tropism is 4.01. The irradiation amount of the above-mentioned ultraviolet rays that can obtain the highest anisotropy is 150 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment treatment.

(Comparative Example 6)

After filtering the liquid crystal alignment agent (7) obtained in Comparative Example 1 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of Time anisotropy value 2.02,200mJ / cm ² of different anisotropy value 2.87,300mJ / cm ² of different tropism is 2.51. The irradiation amount of the above-mentioned ultraviolet rays at the maximum anisotropy is 200 mJ/cm ² , which is the most suitable irradiation condition for the photo-alignment process.

(Comparative Example 7)

After filtering the liquid crystal alignment agent (8) obtained in Comparative Example 2 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of different anisotropy value 5.02,150mJ / cm ² of Time anisotropy value 7.37,200mJ / cm ² of different tropism is 6.40. The irradiation amount of the ultraviolet rays at the maximum anisotropy is 150 mJ/cm ² , which is the most suitable irradiation condition for the photo-alignment process.

(Comparative Example 8)

After filtering the liquid crystal alignment agent (9) obtained in Comparative Example 3 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation is 50mJ / cm ² of Time anisotropy value 4.11,100mJ / cm ² of different anisotropy value 5.78,150mJ / cm ² of different tropism is 4.55. The irradiation amount of the above-mentioned ultraviolet rays at the maximum anisotropy is 100 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment process.

(Comparative Example 9)

After filtering the liquid crystal alignment agent (10) obtained in Comparative Example 4 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 400mJ / cm ² of different anisotropy value 1.60,600mJ / cm ² of different anisotropy value 1.78,800mJ / cm ² of different tropism is 1.33. The irradiation amount of the ultraviolet rays at the maximum anisotropy is 600 mJ/cm ² , which is the most suitable irradiation condition for the photo-alignment process.

(Comparative Example 10)

After filtering the liquid crystal alignment agent (11) obtained in Comparative Example 5 with a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm×40 mm. After drying for 2 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 14 minutes to form a coating film with a thickness of 100nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light with an extinction ratio of 26:1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation is 50mJ / cm ² of Time anisotropy value 5.54,100mJ / cm ² of different anisotropy value 7.34,200mJ / cm ² of different tropism is 6.40. The irradiation amount of the above-mentioned ultraviolet rays at the maximum anisotropy is 100 mJ/cm ² , which is regarded as the most suitable irradiation condition for the photo-alignment process.

(Example 13)

After filtering the liquid crystal alignment agent (1) obtained in Example 1 with a 1.0 μm filter, it was coated with a spin coater on the prepared substrate with the above electrodes and the inner surface of the ITO film formed with columnar spacers with a height of 4 μm The glass substrate of the device. After drying for 5 minutes on a hot plate at 80°C, it is fired in a hot-air circulating oven at 230°C for 20 minutes to form a coating film with a thickness of 100 nm. UV rays with a wavelength of 254nm of linearly polarized light with an extinction ratio of 26:1 are ^{irradiated with 150mJ/cm 2 of} the coating film through a polarizing plate, and then heated on a hot plate at 230°C for 14 minutes to produce an alignment film with liquid crystal. The substrate. Using the above two substrates as a set, a sealant is printed on the substrate, and the other substrate is bonded so that the surface of the liquid crystal alignment film is facing and the alignment direction is 0°, and then the sealant is cured to obtain an empty cell. After the liquid crystal MLC-7026-100 (manufactured by Mork) was injected into the empty cell using a reduced pressure injection method, the injection port was sealed to obtain an FFS driven liquid crystal cell. Subsequently, the obtained liquid crystal cell was heated at 110° C. for 1 hour, and after being left overnight, the residual image was evaluated using long-term AC driving. The value of the angle Δ of the liquid crystal cell after long-term AC driving is 0.08 degrees. In addition, as a result of observing the bright spots in the unit cell, the number of bright spots is less than 10, which is good.

(Example 14)

After irradiating the liquid crystal alignment agent (1) obtained in Example 1 with polarized ultraviolet rays, it was immersed in 2-propanol for 3 minutes, and then immersed in pure water for 1 minute. The others were the same as in Example 13. The FFS driving liquid crystal cell is prepared. For this FFS-driven liquid crystal cell, a long-term AC driving method was used to evaluate the residual image. The value of the angle Δ of the liquid crystal cell after long-term AC driving is 0.10 degrees. In addition, as a result of observing the bright spots in the unit cell, the number of bright spots is less than 10, which is good.

(Examples 15-19)

Except that the liquid crystal alignment agents (2) to (6) obtained in Examples 2 to 6 were used, other coating films with a thickness of 100 nm were formed in the same manner as in Example 13. The ultraviolet rays with a wavelength of 254nm of linearly polarized light with an extinction ratio of 26:1 are irradiated through the polarizer according to the irradiation amount (unit: mJ/cm ² ) described in Table 1 below. In Example 13, a substrate with a liquid crystal alignment film was prepared by the same method, and then each FFS driven liquid crystal cell was fabricated, and the residual image evaluation in long-term AC driving was carried out. The angle Δ value of each liquid crystal cell after long-term AC driving and the results obtained by observing the bright spots in the cell are shown in Table 1. In addition, when the number of bright spots is less than 10, it is marked as good, and when the number of bright spots is 10 or more, it is marked as bad.

(Comparative Examples 11-15)

Except that the liquid crystal alignment agents (7) to (11) obtained in Comparative Examples 1 to 5 were used, the other coating films with a thickness of 100 nm were formed in the same manner as in Example 13. The ultraviolet rays with a wavelength of 254nm of linearly polarized light with an extinction ratio of 26:1 are irradiated on the surface of each coating film according to ^{the irradiation amount (unit: mJ/cm 2) described in Table 1 below through the polarizing plate, and everything else depends on} In the same way as in Example 13, a substrate with a liquid crystal alignment film was prepared, and then each FFS driven liquid crystal cell was fabricated, and the after-image evaluation of long-term AC driving was performed. The angle Δ value of each liquid crystal cell after long-term AC driving and the result of observing the bright spot in the cell are shown in Table 1. In addition, when the number of bright spots is less than 10, it is marked as good, and when the number of bright spots is 10 or more, it is marked as bad.

[Industrial Utilization]

Even when the liquid crystal alignment agent of the present invention uses negative liquid crystals, it does not produce bright spots caused by the decomposition products generated by the liquid crystal alignment film during the photo-alignment process, and is a liquid crystal with good after-image characteristics. Alignment film. Therefore, the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention has extremely low bright spots due to the decrease in contrast, and can reduce the AC drive generated in the liquid crystal display element of the IPS drive mode or the FFS drive mode. The residual image caused by this can be obtained by an IPS drive or FFS drive liquid crystal display device with excellent residual image characteristics. Therefore, it can be used in a liquid crystal display element seeking high display quality.

Claims (12)

A liquid crystal alignment agent, characterized in that it contains a polyimide precursor having the structural unit represented by the following formula (1) and the following formula (2) and an imidization of the polyimine precursor At least one polymer selected from the group of polymers (A);

(In formula (1) and formula (2), X ₁ and X ₂ each independently represent a tetravalent organic group, R ₁ and R ₂ each independently represent a hydrogen atom, or an alkyl group with 1 to 4 carbon atoms, A ₁ , A ₂ , A ₃ , and A ₄ each independently represent a hydrogen atom or an alkyl group with 1 to 4 carbon atoms, and Z ₁ , Z ₂ , Z ₃ , and Z ₄ each independently represent a hydrogen atom, a halogen atom, and a carbon number of 1 ~4 alkyl group, n is an integer of 1~4). The liquid crystal alignment agent of claim 1, wherein the content ratio of the structural unit represented by the above formula (1) is 10-50 mol% relative to 1 mol of the whole structural unit of the above-mentioned polymer (A), and the above formula (2) The content ratio of the structural unit shown is 20 to 90 mol% relative to 1 mol of the entire structural unit of the above-mentioned polymer (A). For the liquid crystal alignment agent of claim 1 or 2, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X _{3 are represented} by the following formulas (X1-1)~( X1-9) at least one selected from the group of structures represented;

(In formula (X1-1), R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbons, an alkenyl group with 2 to 6 carbons, and alkyne Group, or phenyl, which can be the same or different). The liquid crystal alignment agent of claim 1 or 2, wherein the polymer (A) has a structural unit other than formula (1) and formula (2), which is a structural unit represented by the following formula (3);

(In formula (3), X ₃ each independently represents at least one selected from the group of structures represented by formulas (X1-1) to (X1-9), R ₃ is a hydrogen atom, or carbon number 1 ~4 alkyl group, Y ₁ is at least one selected from the group of structures represented by the following formulas [1d-1]~[1d-7])

(In formula [1d-1] to formula [1d-7], D is a tert-butoxymethoxycarbonyl group, and n1 to n5 each independently represent an integer of 1 to 5). The liquid crystal alignment agent of claim 1 or 2, wherein the content ratio of the structural unit represented by the formula (3) is 10-50 mol% relative to 1 mol of the whole structural unit of the above-mentioned polymer (A). The liquid crystal alignment agent of claim 1 or 2, wherein, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X ₃ are represented by the above formula (X1-1) At least one selected from the group of the structure. For the liquid crystal alignment agent of claim 1 or 2, wherein, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X _{3 are represented} by the following formulas (X1-10) and (X1-11) At least one selected from the group of structures represented by (X1-11);

The liquid crystal alignment agent of claim 1 or 2, wherein, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X ₃ are the aforementioned formulas (X1-11). A liquid crystal alignment film, characterized in that it is obtained by irradiating polarized ultraviolet rays on a film obtained by coating and firing the liquid crystal alignment agent of any one of claims 1 to 8. A liquid crystal alignment film, which is characterized by using the liquid crystal alignment agent of claim 1 or 2, which is obtained by an inkjet method. A liquid crystal display element characterized by having the liquid crystal alignment film of any one of claim 9 and claim 10. Such as the liquid crystal display element of claim 11, wherein the liquid crystal is a negative type liquid crystal material.