TW201809231A - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

A liquid crystal alignment agent which can suppress poor coating of the alignment film occurring due to the effects of C/H or the wiring structure, and display non-uniformities in a liquid crystal element, and which further increases the resin component ratio while reducing viscosity of the liquid crystal alignment agent; also provided are a liquid crystal alignment film, and liquid crystal display element. This liquid crystal alignment agent is characterized by containing at least one type of polymer selected from the group consisting of polyimide precursors and polyimides, which are the imidized products thereof, and a solvent containing a solvent A, a solvent B and a solvent C described below. Solvent A: at least one selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, [gamma]-butyrolactone, and dimethyl-imidazolidinone Solvent B: dipropylene glycol dimethyl ether Solvent C: a compound represented by expression (a) (R1 and R2 are independently a linear or branched alkyl group of 1-8 carbon atoms, and the total number of carbons of R1 and R2 is greater than or equal to 4.).

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 an inkjet film formation method and having high dimensional stability during coating, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display provided with the liquid crystal alignment film. element.

As a liquid crystal alignment film, a liquid crystal alignment agent containing a polyimide precursor such as polyamic acid (also referred to as polyamic acid) or a solution of a soluble polyimide as a main component is widely used and fired. So-called polyfluorene-based liquid crystal alignment film.

As the film-forming method of the liquid crystal alignment film, spin coating, dip coating, flexographic printing, and the like are generally known. In practice, flexographic printing is more commonly used. However, in flexographic printing, there are the following problems: various resin plates are required depending on the type of liquid crystal panel; the plates are exchanged in a complicated manner during the manufacturing steps; in order to stabilize the film forming step, It is necessary to form a film on a dummy substrate; the production of a plate has become a cause of an increase in the manufacturing cost of a liquid crystal display panel.

Therefore, the inkjet method has attracted attention as a method for forming a liquid crystal alignment film without using a printing plate. The inkjet method is a method of dripping fine liquid droplets on a substrate and forming a film by infiltration and diffusion of a liquid. Not only Since a printing plate is used, and the pattern to be printed can be freely set, the manufacturing steps of the liquid crystal display element can be simplified. In addition, since it is not necessary to form a film on a dummy substrate in flexographic printing, there is an advantage that the waste of the coating liquid is less. The inkjet method can be expected to reduce the cost of liquid crystal panels and improve the productivity.

The liquid crystal alignment film formed by the inkjet method is required to have a small film thickness inside the coating surface and a high film forming accuracy at the periphery of the coating. In general, there is a trade-off relationship between the uniformity of the film thickness in the coating surface of the liquid crystal alignment film system formed by the inkjet method and the film formation accuracy of the coating peripheral portion. That is, in general, a material having high in-plane uniformity has a low dimensional stability of the coating peripheral portion, and the film exceeds a set size. On the other hand, if the coating peripheral portion becomes a straight material, the uniformity in the coating surface will decrease.

In order to improve the film formation accuracy of the coating peripheral portion, a method is proposed in which the alignment film is sealed within a specified range by a special structure (refer to Patent Documents 1 to 3). However, these methods have the disadvantage of requiring special structures.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2004-361623

[Patent Document 2] Japanese Patent Laid-Open No. 2008-145461

[Patent Document 3] Japanese Patent Laid-Open No. 2010-281925

In recent years, with the high definition of liquid crystal display elements, the design of TFTs for multilayer wiring has become mainstream. In the TFT design, a contact hole (also referred to as C / H) is formed on the substrate in order to connect the lower-layer wiring to the upper-layer wiring. Along with this, due to the influence of the wiring structure or C / H, the liquid diffusing agent is likely to be hindered when the liquid crystal alignment agent is applied. As a result, unevenness in the thickness of the alignment film such as dot-like unevenness or stripe-like unevenness occurs around the C / H or other portions, and the display of the liquid crystal display element may be uneven.

In addition, the liquid crystal alignment agent used in the inkjet method is required to have a low viscosity in order to spit the alignment agent from the inkjet nozzles stably. For this reason, there is a setting to reduce the ratio of the resin component in the liquid crystal alignment agent. situation. On the other hand, in order to make the thickness of the peripheral portion of the liquid crystal alignment film uniform and to suppress the width of the liquid crystal alignment film, it is necessary to maintain the low viscosity of the liquid crystal alignment agent and increase the resin component ratio in the liquid crystal alignment agent. Therefore, such a liquid crystal alignment agent is required.

The present invention is conceived in view of the above-mentioned problems, and provides a liquid crystal alignment film capable of suppressing poor film formation due to the influence of wiring structure or C / H, or non-uniform display of a liquid crystal display element. At the same time when the viscosity is lowered, the liquid crystal alignment agent which can increase the resin component ratio, and the liquid crystal alignment film using the same.

The present inventors finally completed the present invention as a result of repeated and intensive studies in order to solve the above problems.

The gist of the present invention is a liquid crystal alignment agent, which is characterized by containing at least one polymer selected from the group consisting of polyimide precursors and polyimide of amidine imide, and containing a polymer belonging to the following A Solvents of Groups B, C and C, Group A: selected from N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone ( GBL) and 1,3-dimethylimidazolinone (DMI), at least one kind of solvent; group B: dipropylene glycol dimethyl ether (DME); group C: containing the following formula (a Solvent for the compound represented by)

R ₁ and R ₂ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms, but the total number of carbon atoms of R ₁ and R ₂ is 4 or more.

According to the present invention, it is possible to suppress poor film formation of the liquid crystal alignment film or uneven display of the liquid crystal display element due to the influence of the wiring structure or C / H, and it can maintain a low viscosity while maintaining high viscosity. Resin component ratio, so suitable for film formation by inkjet method Polyimide-based liquid crystal alignment agent, liquid crystal alignment film using the same, and liquid crystal display element.

[Best Mode for Implementing Invention]

The liquid crystal alignment agent of the present invention contains at least one polymer (hereinafter also referred to as a specific polymer) selected from the group consisting of a polyimide precursor and a polyimide of a polyimide, and contains Solvents for solvent A, solvent B, and solvent C (hereinafter also referred to as specific solvents).

<Specific solvent>

The solvent contained in the liquid crystal alignment agent of this invention contains the said solvent A, the solvent B, and the solvent C, and is demonstrated separately below.

<Solvent A>

Solvent A is selected from the group consisting of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), and 1,3-dimethyl A solvent of at least one group of imidazolinone (DMI). Solvent A is a polymer that dissolves the polymer in the liquid crystal alignment agent.

Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone (GBL) is preferable, and N-methyl-2-pyrrol Pyridone (NMP), or γ-butyrolactone (GBL).

In the liquid crystal alignment agent of the present invention, the content of the solvent A is preferably 20 to 90% by mass, and 30 to 80% by mass relative to the total mass of the liquid crystal alignment agent. % Is also better, and more preferably 50 to 80% by mass.

<Solvent B>

Solvent B is dipropylene glycol dimethyl ether (DME). Solvent B is a solvent that contributes to the improvement of the uniformity of coating of the liquid crystal alignment agent and the reduction in viscosity.

In the liquid crystal alignment agent of the present invention, the content of the solvent B with respect to the total mass of the liquid crystal alignment agent is preferably 5 to 50% by mass, and more preferably 10 to 50% by mass.

<Solvent C>

The solvent C is a compound represented by the following formula (a).

In formula (a), R ₁ and R ₂ are each independently a linear or branched carbon number 1 to 8, preferably 3 to 8, and more preferably 3 to 6 alkyl groups. However, R ₁ and R ₂ The total carbon number of R ₂ is 4 or more, and preferably 5 to 12.

Specific examples of the solvent C represented by the formula (a) include a-1 to a-48 below, but they are not limited to these.

Among them, in terms of availability and practicality, the solvent C is A-22, a-13 ~ a-21, a-24, a-26, a-27, a-31, a-34, a-37, or a-38 are preferred, and a-22, Or a-37 is more preferable.

In the liquid crystal alignment agent of the present invention, the content of the solvent C is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass for the entire mass of the liquid crystal alignment agent.

In addition, the total content of the solvents B and C is preferably 20 to 50% by mass, and more preferably 20 to 40% by mass relative to the total mass of the liquid crystal alignment agent. In this case, the content of the solvent B is preferably more than the content of the solvent C, and particularly preferably 1 to 20% by mass than the content of the solvent C.

The liquid crystal alignment agent of the present invention may contain a solvent other than the specific solvent. Examples thereof include butyl cellosolve, 1-butoxy-2-propanol, butyl cellosolve acetate, dipropylene glycol monomethyl ether, diacetone alcohol, diethylene glycol diethyl ether, and diisocyanate. Amyl ether, propylene glycol diacetate, diisobutyl ketone, ethyl carbitol and dipropylene glycol dimethyl ether, γ-valerolactone and the like. The solvent other than the specific solvent is preferably 50% by mass or less with respect to the entire mass of the liquid crystal alignment agent, and more preferably 20% by mass or less.

<Specific polymer>

It is preferable that the polyimide precursor of the specific polymer contained in the liquid crystal alignment agent of the present invention has a structure represented by the following formula (1).

In the formula (1), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ₁ is a divalent organic group derived from a diamine. R ₁ is a hydrogen atom or an alkylene group having 1 to 5 carbon atoms. From the viewpoint of the ease of the fluorene imidization reaction during heating, R ₁ is preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group.

A ₁ and A ₂ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. From the viewpoint of liquid crystal alignment, A ₁ and A ₂ are preferably a hydrogen atom or a methyl group.

Hereinafter, each component which is a raw material for manufacturing the said polyfluorene imide precursor is demonstrated.

<Diamine>

The diamine component used in the production of the polyimide precursor is not particularly limited, but the diamine of the raw material of the polyimide precursor represented by the formula (1) is represented by the following formula (2) .

In the formula (2), A ₁ and A ₂ (including a preferable example) have the same definitions as A ₁ and A ₂ in the formula (1). In the case of Y ₁ , the following (Y-1) ~ (Y-170) can be exemplified.

In the formula, n is an integer of 1 to 6, and Me is a methyl group.

Among them, (Y-7), (Y-8), (Y-16), (Y-17), (Y-18), (Y-20), (Y-21), (Y-22) , (Y-28), (Y-35), (Y-38), (Y-43), (Y-48), (Y-64), (Y-66), (Y-71), (Y-72), (Y-76), (Y-77), (Y-80), (Y-81), (Y -82), (Y-83), (Y156), (Y-159), (Y-160), (Y-161), (Y-162) (Y-168), (Y-169), or ( Y-170) is better, especially (Y-7), (Y-8), (Y-16), (Y-17), (Y-18), (Y-21), (Y-22) ), (Y-28), (Y-38), (Y-64), (Y-66), (Y-72), (Y-76), (Y-81), (Y156), (Y -159), (Y-160), (Y-161), (Y-162), (Y-168), (Y-169), or (Y-170) are preferred.

<Tetracarboxylic acid derivative>

The tetracarboxylic acid derivative used in the production of the polyimide precursor is not particularly limited, but the tetracarboxylic acid derivative component as a raw material of the polyimide precursor represented by the formula (1) is not limited to Examples of the tetracarboxylic dianhydride include tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, or tetracarboxylic acid dialkyl ester dihalide.

The tetracarboxylic dianhydride or its derivative is preferably represented by the following formula (3).

In formula (3), X ₁ is a tetravalent organic group having an alicyclic structure, and the structure is not particularly limited. Specific examples include the following formulae (X1-1) to (X1-44).

In the formulae (X1-1) to (X1-4), R ₃ to R ₂₃ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or 2 to 6 carbon atoms. An alkynyl group of 6, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. In terms of liquid crystal alignment, R ₃ to R ₂₃ are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group.

As specific examples of the formula (X1-1), the following formulae (X1-1-1) to (X1-1-6) can be exemplified. In terms of liquid crystal alignment and sensitivity of photoreaction, (X1-1-1) is particularly preferred.

The tetracarboxylic dianhydride and the derivative thereof, which are the precursors of the polyfluorene imide and the raw material of the polyfluorene, of the present invention include 1 mol of all the tetracarboxylic dianhydride and its derivative to include the above formula (3 The tetracarboxylic dianhydride or its derivative represented by) is preferably 60 to 100 mole%. In order to obtain a liquid crystal alignment film with good liquid crystal alignment, it is more preferable to use 80 to 100 mole%. 90 ~ 100 mole% is more preferred.

<Polyimide precursor> <Manufacturing Method of Polyurethane>

The polyamidate, which is one of the polyamidate precursors used in the present invention, can be produced by the method (1), (2), or (3) shown below.

(1) When it is made of polyamic acid

Polyamidates can be synthesized by esterifying a polycarboxylic acid obtained from a tetracarboxylic dianhydride and a diamine.

Specifically, the polyamidic acid and the esterifying agent can be made at -20 ° C to 150 ° C in the presence of an organic solvent, preferably at 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably 1 to The reaction took 4 hours to synthesize.

The esterifying agent is preferably one which can be easily removed by purification, and examples thereof include N, N-dimethylformamide dimethyl acetal and N, N-dimethylformamide diethyl Acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide dineopentylbutyl acetal N, N-dimethylformamide di-t -Butyl acetal, 1-methyl-3-p-tolyl triazene, 1-ethyl-3-p-tolyl triazene, 1-propyl-3-p-tolyl triazene , 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methyl morpholine chloride and the like. The amount of the esterifying agent is preferably 2 to 6 mol equivalents relative to 1 mol of the repeating unit of the polyamic acid.

The solvent used in the above reaction is N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ- Butyrolactone is preferred, and these can be used singly or in combination of two or more. The concentration of the polymer in the reaction solution is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that it is difficult to cause precipitation of the polymer and to obtain a high molecular weight body.

(2) In the case of production by the reaction of tetracarboxylic acid diester dihydrazine and diamine

The polyfluorene ester system can be produced from a tetracarboxylic acid diester dihydrazine chloride and a diamine. Specifically, the tetracarboxylic acid diester diammonium chloride and diamine can be made in the presence of a base and an organic solvent at -20 ° C to 150 ° C, preferably at 0 ° C to 50 ° C for 30 minutes to 24 hours. It is preferable to perform the reaction for 1 to 4 hours for production.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine, and the like can be used, but in order to allow the reaction to proceed stably, pyridine is preferred. The amount of the alkali used is preferably from 2 to 4 times the mole of the tetracarboxylic acid diester dichloride from the viewpoint of an amount that can be easily removed and a high-molecular-weight body can be easily obtained.

As the solvent used in the above reaction, in terms of the solubility of the monomers and polymers, N-methyl-2-pyrrolidone or γ-butyrolactone is preferred, and these may be used alone or in combination. Use 2 or more types. The polymer concentration in the reaction solution is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that it is difficult to cause precipitation of a polymer and to obtain a high molecular weight body. In addition, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloromethane, it is preferable that the solvent used in the synthesis of the polycarbamate is dehydrated as much as possible, and it is better to prevent the mixing of external gases in a nitrogen environment.

(3) In the case where a polycarboxylic acid ester is produced from a tetracarboxylic acid diester and a diamine

The polyamidate system can be produced by polycondensation of a tetracarboxylic acid diester and a diamine. Specifically, the tetracarboxylic acid diester and diamine can be made in the presence of a condensing agent, a base, and an organic solvent at 0 ° C to 150 ° C, preferably at 0 ° C to 100 ° C for 30 minutes to 24 hours. It is preferable to perform the reaction for 3 to 15 hours for production.

As the condensing agent, triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N 'can be used. -Carbonyldiimidazole, dimethoxy-1,3,5-triazinylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetra Methylurea tetrafluoroborate, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethylurea hexafluorophosphate, (2,3-dihydro-2- Thio-3-benzo (Oxazolyl) diphenylphosphonate and the like. The addition amount of the condensing agent is preferably 2 to 3 times the mole of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the alkali used is preferably 2 to 4 times the mole of the diamine component in terms of the amount that can be easily removed and the high molecular weight body is easily obtained.

In the above reaction, the reaction proceeds efficiently by adding a Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferred. The addition amount of the Lewis acid is preferably from 0 to 1.0 times the mole of the diamine component.

In the above-mentioned three types of polyamidate production methods, in order to obtain a high-molecular-weight polyamidate, the above-mentioned (1) or (2) The method is particularly good.

The polymer solution obtained by the above-mentioned method can be precipitated by pouring into a poor solvent while stirring sufficiently. After carrying out precipitation several times, washing | cleaning with a poor solvent, and drying at normal temperature or heating, the powder of the purified polyamic-acid ester can be obtained. The poor solvent is not particularly limited, but examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Manufacturing method of polyamic acid>

The polyamido acid of the polyamido precursor used in the present invention can be produced according to the method shown below.

Specifically, in the presence of an organic solvent, tetracarboxylic dianhydride and diamine can be used at -20 ° C to 150 ° C, preferably at 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably The reaction was carried out for 1 to 12 hours to synthesize.

The organic solvent used in the above reaction is N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in terms of the solubility of the monomers and polymers. For preference, these systems may be used singly or as a mixture of two or more. The concentration of the polymer is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer is unlikely to occur and a high molecular weight is easily obtained.

The polyamidic acid obtained in the manner as described above can be poured into a poor solvent by sufficiently stirring the reaction solution, thereby allowing the polymer to be precipitated and recovered. Further, after performing precipitation several times, washing with a poor solvent, and then drying at room temperature or heating, a purified polymer can be obtained. Phenylamine powder. The poor solvent is not particularly limited, but examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Manufacturing method of polyimide>

The polyamidoimide used in the present invention can be produced by subjecting the aforementioned polyamidate or polyamidoacid to imidization. When a polyimide is produced from a polyamic acid ester, the polyamino acid solution obtained by dissolving the polyamino acid resin powder in an organic solvent, It is easy to add the chemical imidization of alkaline catalyst. The chemical fluorene imidization is preferred because the fluorene imidization reaction is performed at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the fluorene imidization.

The chemical fluorene imidization can be performed by stirring a polyfluorene ester to be fluorinated in an organic solvent in the presence of a basic catalyst. The organic solvent is a solvent that can be used in the aforementioned polymerization reaction. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, triethylamine is preferred because it has sufficient basicity to allow the reaction to proceed.

The temperature at which the amidine imidization reaction is performed may be -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time may be 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mol times of the polyamidate group, preferably 2 to 20 mol times. The hydrazone imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time. Since the added catalyst and the like remain in the solution after the fluorene imidization reaction, the obtained fluorene imidized polymer is recovered and re-dissolved with an organic solvent as the liquid crystal of the present invention. An alignment agent is preferred.

In the case of producing polyimide from polyacrylic acid, a catalyst chemical hydrazone is added to a solution of the polyamic acid obtained by the reaction of a diamine component and a tetracarboxylic dianhydride. Imination is simple. The chemical fluorene imidization is preferred because the fluorene imidization reaction is performed at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the fluorene imidization.

Chemical fluorene imidization can be performed by stirring a polymer to be fluorinated in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, a solvent used in the aforementioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferred because it has a moderate basicity that allows the reaction to proceed. In addition, examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic dianhydride. Among them, when acetic anhydride is used, purification after the reaction is facilitated, so it is preferable.

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

Since the added catalyst and the like remain in the solution after the polyimidation reaction of the polyamic acid ester or polyamic acid, the obtained imidization is recovered by the method described below. The polymer is preferably used as the liquid crystal alignment agent of the present invention after redissolution with an organic solvent.

The polyimide solution obtained as described above is poured into a poor solvent by sufficiently stirring while the polymer is precipitated. After carrying out precipitation several times, washing | cleaning with a poor solvent, and drying at normal temperature or heating, the powder of the purified polyamic-acid ester can be obtained.

The aforementioned poor solvent is not particularly limited, but 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 of the present invention has a solution form in which a specific polymer is dissolved in a solvent containing a specific solvent. The molecular weight of the polyimide precursor and polyimide described in the present invention is preferably 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. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and even more preferably 5,000 to 50,000.

The concentration of the polymer of the liquid crystal alignment agent used in the present invention may be appropriately changed according to the thickness setting of the coating film to be formed. In terms of forming a uniform and defect-free coating film, the weight is 1 weight. % Or more is preferable, and in terms of storage stability of the solution, 10% by weight or less is preferable.

<Other solvents>

The liquid crystal alignment agent of the present invention may contain the above solvents A, B, and C Other solvents (hereinafter also referred to as other solvents). Other solvents may include a solvent (also referred to as a good solvent) that dissolves the polyimide precursor and polyimide, or improves the coating property or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied. Solvents (also known as poor solvents).

Although specific examples of other solvents can be exemplified below, they are not limited to these examples. Examples of good solvents include N, N-dimethylformamide, N, N-dimethylacetamide, dimethylmethylene, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N, N-dimethylpropanamide (IPME) or 4-hydroxy-4-methyl-2-pentanone, etc.

Specific examples of the poor solvent include ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, and 3-pentanol. , 2-methyl-1-butanol, isoamyl alcohol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2 -Methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1 -Hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethylene glycol, 1,2-propylene glycol, 1,3- Propylene glycol, 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 glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethyl ether Glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentylethyl Ester, 2- Butyl acetate, 2-ethylhexyl acetate, ethylene Alcohol monoacetate, ethylene glycol diacetate, propylene carbonate, ethyl acetate, 2- (methoxymethoxy) ethanol, butyl cellosolve, ethylene glycol monoisoamyl ether, ethyl acetate Glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, 1-butoxy-2-propanol, 1- (butoxyethoxy) propanol, propylene glycol mono Methyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether ethyl Acid ester, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diacetone alcohol, propylene glycol diacetic acid Ester, diisoamyl ether, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol , Triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, Methyl pyruvate, ethyl pyruvate, methyl 3-ethoxypropionate Methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, 3-ethoxypropionate, 3-methoxypropionate, 3-methoxypropionate, 3- Butyl methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, diisobutyl ketone, ethyl carbitol and the like.

Examples of the poor solvent include solvents represented by the following formulas [D-1] to [D-3].

In formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], D ³ represents an alkyl group having 1 to 4 carbon atoms.

The liquid crystal alignment agent of the present invention may further include a crosslinkable compound having an epoxy group, an isocyanate group, an oxetanyl group, or a cyclic carbonate, and a member selected from the group consisting of a hydroxyl group, a hydroxyalkyl group, and a lower-order alkoxyalkyl group. Crosslinkable compounds having at least one type of substituent group or crosslinkable compounds having a polymerizable unsaturated bond. These substituents or polymerizable unsaturated bonds must have two or more in a crosslinkable compound.

Examples of the crosslinkable compound having an epoxy group or an isocyanate group include bisphenol acetone glycidyl ether, phenol novolac epoxy resin, cresol novolac epoxy resin, triglycidyl trimeric isocyanate, and tetraglycidylamine. Diphenylene, tetraglycidyl-m-xylylenediamine, tetraglycidyl-1,3-bis (aminoethyl) cyclohexane, tetraphenylglycidyl ether ethane, triphenylglycidyl Etherethane, bisphenol hexafluoroacetamidine diglycidyl ether, 1,3-bis (1- (2,3-epoxypropoxy) -1-trifluoromethyl-2,2,2-tri Fluoromethyl) benzene, 4,4-bis (2,3-epoxypropoxy) octafluorobiphenyl, triglycidyl-p-aminophenol, tetraglycidyl-m-xylylenediamine, 2- (4- (2,3-epoxypropoxy) phenyl) -2- (4- (1,1-bis (4- (2,3-epoxypropoxy) phenyl) ethyl) phenyl) propane or 1,3-bis (4- (1- (4- (2,3-epoxypropoxy) benzene Yl) -1- (4- (1- (4- (2,3-epoxypropoxy) phenyl) -1-methylethyl) phenyl) ethyl) phenoxy) -2- Propanol and so on.

The crosslinkable compound having an oxetanyl group is a compound having at least two oxetanyl groups represented by the following formula [4A].

Specifically, the crosslinkable compound represented by the formula [4a]-a formula [4k] which are listed on page 58-59 of International Publication WO2011 / 132751 (2011.10.27 publication) is mentioned.

The crosslinkable compound having a cyclic carbonate is a crosslinkable compound having at least two cyclic carbonates represented by the following formula [5A].

Specifically, the crosslinkable compound represented by the formula [5-1]-a formula [5-42] which are listed on page 76-82 of International Publication WO2012 / 014898 (2012.2.2 publication) is mentioned.

Examples of the crosslinkable compound having at least one kind of substituent selected from the group consisting of a hydroxyl group and an alkoxy group include, for example, an amine resin having a hydroxyl group or an alkoxy group, and examples thereof include a melamine resin, a urea resin, and a guanamine resin. , Acetylene urea-formaldehyde resin, succinamide-formaldehyde resin or ethylene urea-formaldehyde resin, etc. Specifically, a melamine derivative, a benzoguanamine derivative, or an acetylene urea, in which a hydrogen atom of an amine group is substituted with a methylol group or an alkoxymethyl group or both, can be used. The melamine derivative or benzoguanamine derivative may be a dimer or a trimer. These systems are preferably methylol or alkoxymethyl having an average of 3 to 6 per triazine ring.

Examples of the above-mentioned melamine derivative or benzoguanamine derivative include MX-750 substituted with an average of 3.7 methoxymethyl groups per one triazine ring in a commercially available product, and one triazine per one triazine MW-30 (made by Sanwa Chemical Co., Ltd.) or CYMEL 300, 301, 303, 350, 370, 771, 325, 327, 703, 712, etc., substituted by an average of 5.8 methoxymethyl rings Methylmethylated melamine, CYMEL 235, 236, 238, 212, 253, 254, etc. methoxymethylated butoxymethylated melamine, CYMEL 506, 508, etc. butoxymethylated melamine, such as CYMEL Methoxymethylated isobutoxymethylated melamine containing carboxyl groups such as 1141, methoxymethylated ethoxymethylated benzoguanamine, CYMEL 1123-10, etc. Oxymethylated butoxymethylated benzoguanamine, butoxymethylated benzoguanamine such as CYMEL 1128, methoxymethylated ethoxy containing carboxyl groups such as CYMEL 1125-80 Methylmethyl benzoguanamine (manufactured by Mitsui Cyyanmid Co., Ltd.). In addition, as an example of acetylene urea, butyl such as CYMEL 1170 can be exemplified. Oxymethylated acetylene urea, hydroxymethylated acetylene urea and the like such as CYMEL 1172, and methoxymethylated acetylene urea and the like such as Powderlink 1174.

Examples of the benzene or phenolic compound having a hydroxyl group or an alkoxy group include 1,3,5-ginsyl (methoxymethyl) benzene and 1,2,4-ginsyl (isopropoxymethyl) benzene , 1,4-bis (sec-butoxymethyl) benzene or 2,6-dihydroxymethyl-p-tert-butylphenol.

More specifically, a crosslinkable compound of the formula [6-1] to the formula [6-48] described in pages 62 to 66 of International Publication WO2011 / 132751 (published on 2011.10.27) can be exemplified.

Examples of the crosslinkable compound having a polymerizable unsaturated bond include trimethylolpropane tri (meth) acrylate, neopentaerythritol tri (meth) acrylate, and dipentaerythritol penta (methyl) Cross-linking properties of acrylate, tris (meth) acryloxyethoxytrimethylolpropane, glycerol polyglycidyl ether poly (meth) acrylate, etc. with 3 polymerizable unsaturated groups in the molecule Compounds, and further 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, butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide bisphenol A Type di (meth) acrylate, propylene oxide bisphenol type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, neopentyl Alcohol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, phthalic acid di Glycidyl ester Cross-linking compounds having two polymerizable unsaturated groups in the molecule, such as di (meth) acrylate or hydroxytrimethylacetic acid neopentyl glycol di (meth) acrylate, and 2-hydroxyethyl ( (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl (meth) acrylate, 2- (Meth) acryloxy-2-hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl (meth) acrylate, glycerol mono (meth) acrylate, 2- (formaldehyde) Group) a crosslinkable compound such as acryloxyethyl phosphate and N-methylol (meth) acrylamido having a polymerizable unsaturated group in the molecule.

Furthermore, a compound represented by the following formula [7A] may be used.

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

The crosslinkable compound used in the liquid crystal alignment agent of the present invention may be one kind You can also combine 2 or more types.

The content of the crosslinkable compound in the liquid crystal alignment agent of the present invention is preferably 0.1 to 150 parts by mass relative to 100 parts by mass of the entire polymer component. Among them, in order to perform the crosslinking reaction and exhibit the target effect, it is preferably 0.1 to 100 parts by mass. It is more preferably 1 to 50 parts by mass.

The liquid crystal alignment agent of the present invention may contain a compound that improves the uniformity or surface smoothness of the film thickness of the liquid crystal alignment film when the liquid crystal alignment agent is applied.

Examples of the compound that improves the uniformity or surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, polysiloxane-based surfactants, and nonionic surfactants.

Specific examples include F-Top EF301, EF303, EF352 (manufactured by Tokem Products), MEGAFACE F171, F173, R-30 (manufactured by Dainippon Ink Co., Ltd.), Fluorad FC430, FC431 (above Sumitomo 3M Corporation) ), AashiGuard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), etc.

The amount of the surfactant used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the entire polymer component contained in the liquid crystal alignment agent.

Furthermore, a compound that promotes charge movement in the liquid crystal alignment film and promotes charge release of the device may be added to the liquid crystal alignment agent, as disclosed in pages 69 to 73 of International Publication Gazette WO2011 / 132751 (2011.10.27) The nitrogen-containing heterocyclic amine represented by the formulas [M1] to [M156]. The It is not a problem to directly add the amine to the liquid crystal alignment agent, but it is preferable to add the solution to a solution having a concentration of 0.1 to 10% by mass, preferably 1 to 7% by mass. The solvent is not particularly limited as long as it can dissolve a specific polymer.

The liquid crystal alignment agent of the present invention may contain, in addition to the above-mentioned poor solvent, a crosslinkable compound, a resin film, a compound that improves the uniformity or surface smoothness of the film thickness of the liquid crystal alignment film, and a compound that promotes charge release, The purpose is to improve the adhesion between the liquid crystal alignment film and the substrate as a silane coupling agent, and to heat the polyimide precursor during firing of the coating film to efficiently perform the imidization reaction.醯 Imidation accelerator and so on.

<Liquid crystal alignment film and liquid crystal display element>

The liquid crystal alignment film of the present invention is a film obtained by coating the above-mentioned liquid crystal alignment agent on a substrate, and drying and firing it. The substrate to which the liquid crystal alignment agent of the present invention is applied is not particularly limited as long as it is a substrate having high transparency, and a plastic substrate such as a glass substrate, a silicon nitride substrate, an acrylic substrate, or a polycarbonate substrate may be used. In this case, if a substrate formed with an ITO electrode or the like for driving the liquid crystal is used, it is preferable from the viewpoint of simplification of the manufacturing process. In the case of a reflective liquid crystal display element, if the substrate is only one side, an opaque material such as a silicon wafer may be used. In this case, an electrode that reflects light may be used.

The coating method of the liquid crystal alignment agent is generally carried out by screen printing, lithography, flexographic printing or inkjet method in the industry. As other coating methods, a dipping method, a roll coating method, and a slit coating method are known Method, spin coating method or spray method.

Among them, the liquid crystal alignment agent of the present invention can maintain the high polymer content ratio or the molecular weight of the polymer as described above, and can make the liquid crystal alignment agent low viscosity, so it can be suitably used by the inkjet method. Coating film formation method.

After the liquid crystal alignment agent is coated on the substrate, the liquid crystal alignment film can be formed by evaporating the solvent by heating means such as a hot plate, a thermal cycle type oven, or an IR (infrared) type oven. The steps of drying and firing after applying the liquid crystal alignment agent can be selected at any temperature and time. In general, in order to sufficiently remove the solvent contained, for example, conditions such as firing at 50 to 120 ° C for 1 to 10 minutes, and then firing at 150 to 300 ° C for 5 to 120 minutes. The thickness of the fired liquid crystal alignment film may decrease the reliability of the liquid crystal display element if it is too thin. Therefore, the thickness is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

After the liquid crystal alignment agent of the present invention is coated on a substrate and fired, it can be subjected to alignment treatments such as rubbing treatment or photo alignment treatment, and can also be used as a liquid crystal alignment film without vertical alignment when used for vertical alignment applications. A known method or device can be used for the alignment process such as the rubbing process or the photo-alignment process.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. In addition, each pixel portion constituting the screen display may be a liquid crystal display element having an active matrix structure provided with a switching element such as a TFT (Thin Film Transistor).

Specifically, a transparent glass substrate is prepared, and a common electrode is provided on one substrate and a segment electrode is provided on the other substrate. These electrodes can be used, for example, as ITO electrodes, and can be patterned in such a manner as to display a desired screen display. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film is, for example, a film of SiO ₂ -TiO ₂ formed by a sol-gel method.

Next, a liquid crystal alignment film is formed on each substrate. On one substrate, the liquid crystal alignment films face each other so as to overlap with each other, and the periphery is adhered with a sealant. In order to control the substrate gap, a spacer is usually mixed into the sealant, and a spacer for controlling the substrate gap is also preferably dispersed in the in-plane portion where the sealant is not provided. A part of the sealant may be provided with an opening portion capable of filling the liquid crystal from the outside. Next, a liquid crystal material is injected into a space surrounded by the two substrates and the sealant through an opening provided in the sealant, and then the opening is sealed with an adhesive. As the injection system, a vacuum injection method can be used, and a method using a capillary phenomenon in the atmosphere can also be used. The liquid crystal material may be either a positive liquid crystal material or a negative liquid crystal material, but a negative liquid crystal material is preferred. Next, set the polarizing plate. Specifically, a pair of polarizing plates is stuck on the surface opposite to the liquid crystal layer of two substrates.

[Example]

The following examples illustrate the invention in more detail, but the invention is not limited to these. The abbreviations used in the following are as follows.

DA-1: 1,5-bis (4-aminophenoxy) pentane

DA-2: 4,4'-diaminodiphenylmethane

DA-3: 4,4'-diaminodiphenylamine, CA-1: pyromelite dianhydride

CA-2: 1,2,3,4-cyclobutane tetracarboxylic dianhydride

CA-3: 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride

NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone, BCS: butyl cellosolve, PB: 1-butoxy-2-propanol

DME: Dipropylene glycol dimethyl ether

DPM: Dipropylene glycol monomethyl ether

DAA: diacetone alcohol, DEDG: diethylene glycol diethyl ether

DIBC: 2,6-dimethyl-4-heptanol

AD-1: Compound of the formula

<Determination of viscosity>

The viscosity of the polyamic acid, the liquid crystal alignment agent, and the like are measured at a temperature of 25 ° C. using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

<Determination of solid content concentration>

Measure 1.0 g of the solution in an aluminum cup and feed it at 200 ° C for 2 hours. After the heat treatment, the amount of solids remaining on the cup was measured, and the solid content concentration of the solution was determined.

[Manufacture of Polyamic Acid A1]

In a 2000 ml flask equipped with a stirring device and a nitrogen introduction tube, 171.8 g of DA-1 was placed, and 1676 g of NMP was added, and the mixture was stirred and dissolved while sending nitrogen gas. This diamine solution was added with 113.8 g of CA-1 while stirring under water cooling, and further NMP was added so that the solid content concentration became 12% by weight. Under a nitrogen environment, the solution was stirred for 20 hours while heating at 50 degrees. A solution of polyamic acid (A1) (viscosity: 90 mPa.s) was obtained. 1.0 g of this polyamic acid (A1) solution was measured in an aluminum cup, and the solid content concentration at the time of processing at 200 ° C for 2 hours was 11.2% by weight.

[Manufacturing of Polyamic Acid Solution a1]

With respect to 535.7 g of the polyamic acid (A1) solution, 264.3 g of NMP and 200.0 g of BCS were added to obtain a polyamic acid solution (a1) solution having a solid concentration concentration of 6.0% by weight.

[Manufacturing of Polyamic Acid Solution a2]

With respect to 535.7 g of the polyamic acid (A1) solution, 264.3 g of NMP and 200.0 g of PB were added to obtain a polyamic acid solution (a2) solution having a solid concentration concentration of 6.0% by weight.

[Manufacturing of Polyamic Acid Solution a3]

With respect to 535.7 g of the polyamic acid (A1) solution, 264.3 g of NMP and 200.0 g of DME were added to obtain a polyamic acid solution (a3) having a solid content concentration of 6.0% by weight.

[Manufacture of Polyamic Acid A2]

In a 2000 ml flask equipped with a stirring device and a nitrogen introduction tube, 100.8 g of DA-1 and 34.9 g of DA-5 were placed, and then 1337 g of NMP was added. The mixture was stirred and dissolved while sending nitrogen gas. 92.2 g of CA-1 was added to this diamine solution while stirring under water cooling, and then NMP was added so that the solid content concentration became 12% by weight. Under a nitrogen environment, the solution was stirred for 20 hours while being heated to 50 ° C. Solution of polyamic acid (A2) (viscosity: 520 mmPa.s).

[Manufacture of Polyamic Acid B1]

In a 2000 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, 87.7 g of DA-3 was placed, and 1052.5 g of a solvent (the following solvent 1) blended with NMP and GBL at a ratio of 50% by weight was added. Stir and dissolve while feeding nitrogen. 70.1 g of CA-2 and 382.7 g of solvent 1 were added to this diamine solution while stirring under water cooling, and the mixture was stirred under water cooling for 3 hours under a nitrogen atmosphere. After that, 21.8 g of DA-2 and 191.3 g of solvent 1 were added and stirred. After DA-2 was dissolved, 33.0 g of CA-3 and 287.0 g of solvent 1 were added, and by stirring again under water cooling under a nitrogen environment for 3 hours, a polyamic acid having a solid content concentration of 9.8% by weight was obtained. (B1) solution (viscosity: 65mPa. s). The solid content concentration when 1.0 g of this polyamic acid (B1) solution was measured in an aluminum cup and treated at 200 ° C for 2 hours was 9.8% by weight.

[Manufacturing of Polyamic Acid B2]

In a 2000 ml four-necked flask equipped with a stirring device and a nitrogen introduction tube, 95.6 g of DA-3 and 18.2 g of DA-4 were placed, and 967 g of NMP was added. The nitrogen was stirred and dissolved while sending nitrogen gas. 54.8 g of CA-2 and 276 g of NMP were added to this diamine solution while stirring under water cooling, and the mixture was stirred under water cooling for 3 hours under a nitrogen environment. Thereafter, 75.0 g of CA-4 and NMP were added so that the solid content concentration became 15% by weight, and the mixture was heated to 50 ° C. for 12 hours under a nitrogen environment to obtain a polyamic acid (B2) solution (viscosity: 302mmPa.s).

[Example 1]

153.4 g of a solution of polyamic acid (B1) was weighed, and 1.3 g of NMP, 38.5 g of 3-glycidyloxypropyltriethoxysilane containing 1.3% by weight GBL solution, 95.9 were added to the solution, and 95.9 g of GBL, 53.5 g of DME, and 50.0 g of DIBC were stirred at room temperature for 1 hour. Thereafter, 107.5 g of a3 was added, and by stirring for 1 hour, 500.0 g of a solid content: NMP: GBL: DME: DIBC ratio of 4.3: 30: 40.7: 15: 10 (% by weight) was obtained ( C1).

[Example 2]

Measure 153.4 g of a polyamidic acid (B1) solution, and add 1.3 g of NMP and 38.5 g of a GBL solution containing 3-glycidyloxypropyltriethoxysilane to the solution. 120.9 g of GBL, 28.5 g of DME, and 50.0 g of DIBC were stirred at room temperature for 1 hour. Thereafter, 107.5 g of a3 was added, and by stirring for 1 hour, 500.0 g of a solid content: NMP: GBL: DME: DIBC = 4.3: 30: 40.7: 10: 10 (% by weight) solution (C2) was obtained. .

[Example 3]

After stirring a mixed solution of 33.3 g of a 12% by weight polyamic acid (A2) solution and 106.6 g of a 15% by weight polyamic acid (B2) solution, the mixture was stirred for 30 minutes, and 11.1 g of NMP, 20.0 g of 3-glycidyloxypropyltriethoxysilane containing 1.0% by weight of NMP solution, 204.0 g of GBL, 75.0 g of DME, and 50.0 g of DIBC were stirred at room temperature for 3 hours, Thus, a solution (C8) of 500.0 g of the polymer solid content ratio of A2 and B2 of 2: 8 and the solid content: NMP: GBL: DME: DIBC = 4.2: 30: 40.8: 15: 10 (% by weight) can be obtained. .

[Example 4]

After stirring a mixed solution of 33.3 g of a 12% by weight polyamidic acid (A2) solution and 106.6 g of a 15% by weight polyamidic acid (B2) solution, the mixture was stirred for 30 minutes, and then 5.1g of NMP, 20.0g of 3-glycidoxypropyltriethoxysilane containing 1.0% by weight of NMP solution, 6.0g of AD-1 containing 10% by weight of NMP solution, 204.0g of GBL, 75.0g of DME and 50.0g of DIBC can be obtained by stirring at room temperature for 3 hours to obtain 500.0g of polymer A2 and B2 with a solid content ratio of 2: 8 and solid content: NMP: GBL: DME: DIBC = 4.2: 30 : 40.8: 15: 10 (% by weight) solution (C9).

[Comparative Example 1]

Measure 153.4g of polyamidic acid (B1) solution, add 1.3g of NMP, 38.5g of 3-glycidyloxypropyltriethoxysilane containing 1.3% by weight GBL solution, 145.9 g of GBL and 53.5 g of DME were stirred at room temperature for 1 hour. Thereafter, 107.5 g of a3 was added, and by stirring for 1 hour, 500.0 g of a solid content: NMP: GBL: DME = 4.3: 30: 50.7: 15 (% by weight) solution (C3) was obtained.

[Comparative Example 2]

Measure 153.4g of polyamidic acid (B1) solution, add 1.3g of NMP, 38.5g of 3-glycidyloxypropyltriethoxysilane containing 1.3% by weight GBL solution, 145.9 g of GBL and 53.5 g of BCS were stirred at room temperature for 1 hour. Thereafter, 107.5 g of a1 was added, and by stirring for 1 hour, 500.0 g of a solid content: NMP: GBL: BCS = 4.3: 30: 50.7: 15 (% by weight) solution (C4) was obtained.

[Comparative Example 3]

Measure 153.4g of polyamidic acid (B1) solution, and add 1.3g of NMP and 38.5g of 3-glycidyloxypropyltriethoxysilane to this solution. The solution was a 1.3% by weight GBL solution, 95.9 g of GBL, 53.5 g of BCS, and 50.0 g of DPM, and stirred at room temperature for 1 hour. Thereafter, 107.5 g of a1 was added, and by stirring for 1 hour, 500.0 g of a solid content: NMP: GBL: BCS: DPM = 4.3: 30: 40.7: 15: 10 (% by weight) solution (C5) was obtained. .

[Comparative Example 4]

153.4 g of a solution of polyamic acid (B1) was weighed, and 1.3 g of NMP, 38.5 g of 3-glycidyloxypropyltriethoxysilane containing 1.3% by weight GBL solution, 95.9 were added to the solution, and 95.9 g GBL, 53.5 g of DME, and 50.0 g of DPM were stirred at room temperature for 1 hour. Thereafter, 107.5 g of a3 was added, and by stirring for 1 hour, a solid content of 500.0 g: NMP: GBL: DME: DPM = 4.3: 30: 40.7: 15: 10 (% by weight) solution (C6) was obtained. .

[Comparative Example 5]

153.4 g of a solution of polyamic acid (B1) was weighed, and 1.3 g of NMP, 38.5 g of 3-glycidyloxypropyltriethoxysilane containing 1.3% by weight GBL solution, 95.9 were added to the solution, and 95.9 g of GBL, 53.5 g of PB, and 50.0 g of DPM were stirred at room temperature for 1 hour. Thereafter, 107.5 g of a2 was added, and by stirring for 1 hour, 500.0 g of a solid content: NMP: GBL: PB: DPM = 4.3: 30: 40.7: 15: 10 (% by weight) solution (C7) was obtained. .

For Examples 1 to 4 and Comparative Examples 1 to 5, those having a pore diameter of 1 μm were used. After the filter was filtered, the viscosity was measured and shown in Table 2. Then, the following applicability evaluation was performed.

[Evaluation of inkjet coatability]

Examples 1-4 and Comparative Examples 1 to 5 prepared as described above were applied to a TFT substrate using an inkjet coating device (manufactured by Ishii Keiki Co., Ltd.). The coating conditions were performed with a nozzle pitch of 127 μm, a coating speed of 250 mm / sec, a dispensing amount of 70 pL, and a coating area of 36 × 36 mm. In addition, the coating was pre-dried on a hot plate at 110 ° C for 1 minute, and then fired using an IR oven at 230 ° C for 15 minutes. The coating was performed under the condition that the thickness of the coating film was 120 nm.

[Evaluation method of coating film]

The coated substrate was pre-dried at 110 ° C, and the obtained coating film was compared with the degree of dot or line-shaped unevenness due to the effect of contact holes or wiring, and evaluated in the following four stages.

It can be confirmed by visual inspection that Lv4 is set for those who show obvious unevenness, Lv3 is used for those who can be visually confirmed as uneven, and Lv2 is used for those who cannot see the unevenness by visual inspection. Even if using an optical microscope, there is no unevenness at all. This is set to Lv1.

Further, coating was also performed on a glass substrate on which chromium was vapor-deposited on the surface, and a vernier caliper was used to measure the width of a portion having a hue change (film thickness unevenness) at the end of the coating film, and evaluated as the Halo size. However, if the value of Halo is smaller, it is regarded as a good coating film.

Furthermore, the coating film width was actually measured, and the difference between the actual measured value and the set value with respect to the set coating area was evaluated as dimensional stability. However, a smaller value in this evaluation is considered to be a good coating film.

These results are shown in Tables 1 and 2.

Here, the entire contents of the specification, patent application scope, drawings, and abstract of Japanese Patent Application No. 2016-072567 filed on March 31, 2016 are incorporated herein as a disclosure of the specification of the present invention.

Claims (14)

A liquid crystal alignment agent, which is characterized by containing at least one polymer selected from the group consisting of a polyimide precursor and a polyimide of a polyimide, and a solvent A, a solvent B, and Solvent for solvent C, solvent A: at least 1 selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, and dimethylimidazolinone Species; solvent B: dipropylene glycol dimethyl ether; solvent C: a compound represented by the following formula (a) (R ₁ and R ₂ are each independently a linear or branched alkyl group having 1 to 8 carbon atoms, but the total number of carbon atoms of R ₁ and R ₂ is 4 or more). The liquid crystal alignment agent according to claim 1, wherein the solvent A is N-methyl-2-pyrrolidone or γ-butyrolactone. For example, the liquid crystal alignment agent of claim 1, wherein the solvent C is at least one selected from the group consisting of the following formulas a-1 to a-48, The liquid crystal alignment agent according to any one of claims 1 to 3, wherein the solvent C is at least one selected from the group consisting of the following formulas a-22 and a-37, The liquid crystal alignment agent according to any one of claims 1 to 4, wherein the polyfluorene imide precursor has a structure represented by the following formula (1), (X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine, R ₁ is a hydrogen atom or an alkylene group having 1 to 5 carbon atoms, A ₁ and A ₂ is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms or an alkynyl group having 2 to 5 carbon atoms). The liquid crystal alignment agent according to any one of claims 1 to 5, which contains 20 to 80% by mass of the solvent A with respect to the entire mass of the liquid crystal alignment agent. The liquid crystal alignment agent according to any one of claims 1 to 6, wherein the solvent B is contained in an amount of 1 to 30% by mass based on the entire mass of the liquid crystal alignment agent. The liquid crystal alignment agent according to any one of claims 1 to 7, which contains 1 to 30% by mass of the solvent C with respect to the entire mass of the liquid crystal alignment agent. For example, the liquid crystal alignment agent according to any one of claims 1 to 8, wherein the total of the solvent A is 50 to 80% by mass, the solvent B is 1 to 30% by mass, and the solvent C is Contains 1 to 20% by mass. The liquid crystal alignment agent according to any one of claims 1 to 9, wherein the total amount of the solvent B and the solvent C is 10 to 60% by mass with respect to the entire mass of the liquid crystal alignment agent, and contains more solvents than the solvent C B. The liquid crystal alignment agent according to any one of claims 1 to 9, which contains 1 to 20% by mass of the solvent B as compared with the solvent C. The liquid crystal alignment agent according to any one of claims 1 to 11, which is used for film formation by an inkjet method. A liquid crystal alignment film obtained by the liquid crystal alignment agent according to any one of claims 1 to 12. A liquid crystal display element comprising a liquid crystal alignment film according to claim 13.