TWI699400B - Liquid crystal alignment agent - Google Patents

Abstract

Provided is a liquid crystal alignment agent suitable for inkjet methods, which can obtain a liquid crystal alignment film with excellent film thickness uniformity, film end linearity and dimensional stability.

A liquid crystal alignment agent containing at least one polymer selected from the group consisting of polyamide acid, polyamide ester and polyimide, and a liquid crystal alignment agent with a solvent, the aforementioned solvent containing (A) γ-valerolactone, (B) γ-butyrolactone, and (C) a compound represented by the following formula (c). Furthermore, R ¹ and R ³ are hydrogen atoms, etc., R ² is an alkanediyl group with 2 or 3 carbons, n is 1 or 2, and R ⁴ is an alkyl group with 1 to 5 carbons.

Description

Liquid crystal alignment agent

The present invention relates to a liquid crystal alignment agent for obtaining a liquid crystal alignment film, and particularly relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element suitable for coating by an inkjet method.

As a liquid crystal alignment film used in a liquid crystal display element and the like, a polyimide-based resin film has been widely used. The polyimide-based liquid crystal alignment film is formed by coating a liquid crystal alignment agent mainly composed of polyamide acid, polyamide ester, polyimide, etc., and a solvent on the substrate. Make.

In the past, as the coating method of the liquid crystal alignment agent, the mainstream was the flexographic printing method, but in recent years, from the viewpoint of cost advantages, the inkjet method has gradually increased. However, the liquid crystal alignment film coated by the inkjet method has a trade-off relationship between the uniformity of the film thickness in the coating surface and the shape control of the coating end.

For example, when the liquid crystal alignment agent with high uniformity in the coating film surface is coated by the inkjet method, the shape of the coating film end will be disordered instead of becoming a straight line, or the moisture will spread beyond the set size to make the liquid crystal alignment film Cover to unnecessary parts. Conversely, if a liquid crystal alignment agent that makes the ends of the coating film a straight line or a liquid crystal alignment agent with little wetness and spreading is used, there will be problems such as insufficient in-plane uniformity.

For such a problem, a method of enclosing the liquid crystal alignment agent in a specified range by a structure has been proposed (refer to Patent Document 1, Patent Document 2, and Patent Document 3). In addition, with the composition of the liquid crystal alignment agent as a solution, it has been proposed to use alkyl cellosolve acetate as a solvent to improve the uniformity of the coating film surface and the straight line at the end of the coating film. Sexual method (refer to Patent Document 4), or use alkyl cellosolve acetate and dipropylene glycol monomethyl ether in a solvent to simultaneously improve the uniformity of the coating film surface and the dimensional stability of the coating film Method (refer to Patent Document 5) and so on.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2004-361623 A

[Patent Document 2] JP 2008-145461 A

[Patent Document 3] JP 2010-281925 A

[Patent Document 4] Specification of International Publication WO2012/133826

[Patent Document 5] Specification of International Publication No. WO2014/024885

Among the above-mentioned conventional methods, the method of using structures has The so-called disadvantage of increasing the manufacturing steps of the liquid crystal panel. In addition, the method of using alkyl cellosolve acetate in the solvent, or the method of using alkyl cellosolve acetate and dipropylene glycol monomethyl ether in combination, although excellent effects can be obtained respectively, but the problem has not been achieved yet. Achieve sufficient characteristics.

The purpose of the present invention is to provide a new type of liquid crystal alignment agent suitable for the inkjet method, which is excellent in the uniformity of the film thickness in the coating film surface, the linearity of the end of the coating film, and the dimensional stability of the coating film.

As a result of in-depth examination, the inventor finally completed the present invention which can achieve the above-mentioned problem. That is, the present invention is an invention having the following gist.

1. A liquid crystal alignment agent comprising at least one polymer selected from the group consisting of polyamide acid, polyamide acid ester, and polyimide, and a liquid crystal alignment agent with a solvent, characterized by the aforementioned The solvent contains (A) γ-valerolactone, (B) γ-butyrolactone, and (C) a compound represented by the following formula (c),

(In the formula, R ¹ and R ³ are each independently a hydrogen atom, an alkyl group with 1 to 4 carbons, or an acetyl group, R ² is an alkanediyl group with 2 or 3 carbons, and n is 1 or 2).

2. The liquid crystal alignment agent of 1 above, wherein the content of (A) is 20 to 75% by mass of the entire solvent.

3. The liquid crystal alignment agent as described in 1 above, wherein the content of (A) is 20 to 75% by mass, the content of (B) is 20 to 75% by mass, and the content of (C) relative to the total solvent The amount is 5-60% by mass.

4. The liquid crystal alignment agent of 1 above, wherein the solvent further contains N-methyl-2-pyrrolidone (1-methyl-2-pyrrolidone).

5. The liquid crystal alignment agent according to 4 above, wherein the content of (A) is 20 to 70% by mass, the content of (B) is 20 to 70% by mass, and the content of (C) is 20 to 70% by mass relative to the total solvent The amount is 5 to 55% by mass, and the content of N-methyl-2-pyrrolidone is 3 to 55% by mass.

6. The liquid crystal alignment agent according to any one of 1 to 5 above, wherein the content of the polymer is 1 to 5% by mass.

7. The liquid crystal alignment agent of any one of 1 to 6 above, which is used to coat a substrate by an inkjet method.

8. A liquid crystal alignment film characterized by being obtained from the liquid crystal alignment agent of any one of 1 to 7 above.

9. A method for manufacturing a liquid crystal alignment film, characterized in that the liquid crystal alignment agent of any one of 1 to 6 is applied by an inkjet method.

10. A liquid crystal display element characterized by comprising the liquid crystal alignment film of 8 above.

With the liquid crystal alignment agent of the present invention, especially even when the inkjet method is used, the uniformity of the film thickness in the film surface or the linearity and dimensional stability of the film periphery can be obtained on the substrate. LCD with To the membrane. Thereby, a highly reliable liquid crystal display element whose defects such as display unevenness are suppressed can be obtained.

[Best form to implement invention] <Polymer>

The liquid crystal alignment agent of the present invention contains at least one polymer selected from the group consisting of polyamide acid, polyamide acid ester, and polyimide. The structure of these polymers is not particularly limited as long as they can be used as liquid crystal alignment films. In addition, one type of these polymers can be used in the liquid crystal alignment agent of the present invention, or multiple types can be mixed.

As preferable polyamide acid, polyamide acid ester, and polyimide in the present invention, a polymer having a repeating unit represented by the following formula (1) can be exemplified. In addition, as a preferable polyimide, a polymer having a repeating unit represented by formula (1) can be exemplified by the structure of intramolecular condensation accompanied by the separation of OR and A to form an imide ring The polymer.

In the above formula (1), X represents a tetravalent organic group, two R systems represent a hydrogen atom or a monovalent organic group, respectively, and Y represents a divalent organic group. Organic group, the two A series respectively represent a hydrogen atom or a monovalent organic group. In addition, the X, Y, R, and A systems may be mixed in the polymer in plural structures.

Furthermore, a polymer composed of repeating units in which both Rs of the above formula (1) are hydrogen atoms is polyamide acid, and at least part of R in the polyamide acid is a polymerization of monovalent organic groups The product is polyamide ester. In addition, a polymer in which at least a part of OR is separated from A corresponding to the OR and undergoes intramolecular condensation to form an imine ring is polyimide.

The structure of X in the aforementioned formula (1) is not particularly limited, and the following X-1 to X-46 can be exemplified if a specific example is shown.

Among the above, X-1, X-2, X-3, X-4, X-5, X-6, X-8, X-16, X-19, X-21, X-25, X -26, X-27, X-28 or X-32 are preferred. The preferred X is preferably 2-100 mol% of the entire X in the polymer, and more preferably 40-100 mol%.

The structure of Y in the aforementioned formula (1) is not particularly limited. If a specific example is shown, the following Y-1 to Y-103 can be exemplified.

Among the above, in terms of obtaining good liquid crystal alignment, Y-7, Y-8, Y-10, Y-11, Y-12, Y-13, Y-20, Y-21, Y- 22, Y-23, Y-25, Y-26, Y-27, Y-28, Y-29, Y- 30, Y-41, Y-42, Y-43, Y-44, Y-45, Y-46, Y-48, Y-61, Y-63, Y-64, Y-71, Y-72, Y-73, Y-74, Y-75, or Y-98 are preferred. The preferable content of Y is preferably 1-100 mol% of the total Y in the polymer, and more preferably 50-100 mol%.

In addition, by reducing the volume resistivity of the liquid crystal alignment film, the residual image caused by the accumulation of DC voltage can be reduced, and the structure having heteroatoms in the polymer, the polycyclic aromatic structure, or the combination can be used. The benzene structure is preferable. As the above Y, Y-19, Y-23, Y-25, Y-26, Y-27, Y-30, Y-31, Y-32, Y-33, Y-34, Y-35, Y -36, Y-40, Y-41, Y-42, Y-44, Y-45, Y-49, Y-50, Y-51, or Y-61 are more preferred, Y-31, or Y -40 is particularly good. The content of the above-mentioned Y is preferably 1 to 100 mol% of the entire Y contained in the polymer, and more preferably 50 to 100 mol%.

In addition, in terms of improving the pretilt angle of the liquid crystal, the branch of the polymer preferably has a structure having a long-chain alkyl group, an aromatic ring, an aliphatic ring, a steroid skeleton, or a combination thereof. As the above Y, Y-76, Y-77, Y-78, Y-79, Y-80, Y-81, Y-82, Y-83, Y-84, Y-85, Y-86, Y -87, Y-88, Y-89, Y-90, Y-91, Y-92, Y-93, Y-94, Y-95, Y-96, or Y-97 are more preferred. The content of the above Y is preferably 10 to 90 mol% of the entire Y contained in the polymer, and more preferably 10 to 40 mol%.

The two R systems in the aforementioned formula (1) each independently represent a hydrogen atom or a monovalent organic group. If it is a monovalent organic group, use aryl or carbon An alkyl group of 1 to 4 is preferred. If a specific example is shown, a hydrogen atom, a methyl group, an ethyl group, etc. can be exemplified. Moreover, if a polymer having a repeating unit represented by formula (1) is used as a polyimide precursor, from the viewpoint of the ease of causing intramolecular condensation, R is a hydrogen atom or a methyl group. For better.

The two A systems in the aforementioned formula (1) each independently represent a hydrogen atom or a monovalent organic group. In the case of a monovalent organic group, an alkyl group, alkenyl group, or alkynyl group having 1 to 10 carbon atoms is preferred. Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, t-butyl, hexyl, octyl, decyl, cyclopentyl, cyclohexyl, and dicyclohexyl. As the alkenyl group, one or more CH ₂ -CH ₂ structures existing in the above-mentioned alkyl group may be substituted with CH=CH structures, and more specifically, vinyl, allyl, 1-propylene Group, isopropenyl, 2-butenyl, 1,3-butadienyl, 2-pentenyl, 2-hexyl, cyclopropenyl, cyclopentenyl, cyclohexyl, etc. As the alkynyl group, one or more of the CH ₂ -CH ₂ structure existing in the aforementioned alkyl group can be substituted with a C≡C structure. More specifically, ethynyl, 1-propynyl, 2 -Propynyl etc.

<Manufacturing method of polyamide acid>

Polyamide acid can be obtained by the reaction of tetracarboxylic dianhydride and diamine. For example, polyamide acid composed of repeating units in which both Rs of the aforementioned formula (1) are hydrogen atoms is represented by the tetracarboxylic dianhydride represented by the following formula (2) and formula (3) It can be obtained by the reaction of the diamine indicated. X in the formula (2), and Y and A in the formula (3) are the same as those defined in the aforementioned formula (1).

Specifically, by combining tetracarboxylic dianhydride and diamine 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 1-12 hours.

The organic solvent used in the above reaction is based on N,N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolidone in terms of the solubility of monomers and polymers. Esters are preferred, and these systems may be used alone or in combination of two or more. In terms of the concentration of the polymer in the reaction system, the precipitation of the polymer is less likely to occur and the high molecular weight body is easily obtained, preferably 1-30% by mass, and more preferably 5-20% by mass.

The obtained polyamic acid system can be poured into a poorly soluble polymer solvent (hereinafter also referred to as a weak solvent) while sufficiently stirring the reaction solution to precipitate and recover the polymer. In addition, after performing precipitation several times, washing with a weak solvent, and drying at room temperature or by heating, a purified polyamide acid powder can be obtained. The weak solvent is not particularly limited, and examples include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene. The weight average molecular weight of polyamide acid is preferably 10,000-305,000, and more preferably 20,000 ~210,000. In addition, the number average molecular weight is preferably 5,000 to 152,500, and more preferably 10,000 to 105,000.

<Manufacturing method of polyamide ester> (1) When synthesized from polyamide acid

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

Specifically, by combining the polyamide acid and the esterifying agent 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 is allowed to react in 1 to 4 hours, and the synthesis can be carried out.

As the esterification agent, those that can be easily removed by purification are preferred. Examples include 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-1,3,5triazin-2-yl)-4-methylmorpholine chloride, etc. The addition amount of the esterification agent is preferably 2-6 mol equivalent with respect 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 , These systems can be used alone or in combination of two or more. The concentration of polymer in the reaction system is not easy to produce polymer precipitation, In addition, from the viewpoint of easy availability of a high-molecular weight body, 1 to 30% by mass is preferable, and 5 to 20% by mass is more preferable.

(2) When synthesizing by the reaction of tetracarboxylic acid diester dichloride and diamine

Polyurethane can also be synthesized from tetracarboxylic acid diester dichloride and diamine. For example, the polyamide ester in which two Rs of the aforementioned formula (1) are both monovalent organic groups is represented by the tetracarboxylic acid diester dichloride represented by the following formula (4), and the aforementioned formula (3) ) Can be obtained by the reaction of the diamine represented by. The R system of the formula (4) is the same as the definition in the aforementioned formula (1).

Specifically, by combining tetracarboxylic acid diester dichloride and diamine in the presence of a base and an organic solvent under the conditions of -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes to It is allowed to react for 24 hours, preferably 1 to 4 hours, so that synthesis can be performed.

As the aforementioned base, pyridine, triethylamine, 4-dimethylaminopyridine, etc. can be used, and pyridine is preferred in order to make the reaction proceed smoothly. The amount of the base added is preferably 2 to 4 times moles relative to the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and easy obtaining of high molecular weight products.

The solvent used in the above reaction is monomer and polymerization In terms of the solubility of the substance, N-methyl-2-pyrrolidone or γ-butyrolactone is preferred, and these systems may be used alone or in combination of two or more. In terms of the polymer concentration in the reaction system, the precipitation of the polymer is less likely to occur and the high molecular weight body is easily obtained, 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, so as to prevent external air from being affected in a nitrogen atmosphere. Mixing is better.

(3) When polyamide acid is synthesized from tetracarboxylic acid diester and diamine

Polyurethane can also be synthesized by polycondensing tetracarboxylic acid diester and diamine. For example, the polyamide ester in which two Rs of formula (1) are both monovalent organic groups is represented by the tetracarboxylic acid diester represented by the following formula (5) and the aforementioned formula (3) It can be obtained by the reaction of diamine. Furthermore, the R system of the formula (5) is the same as the definition in the aforementioned formula (1).

Specifically, by combining a tetracarboxylic acid diester and a diamine in the presence of a condensing agent, a base, and an organic solvent under the conditions of 0°C to 150°C, preferably 0°C to 100°C, for 30 minutes to 24 hours, preferably 3~15 hours It can be synthesized by reacting at that time.

唑基)膦酸二苯酯等。縮合劑的添加量，相對於四羧酸二酯，以2~3倍莫耳為較佳。 As the aforementioned condensing agent, triphenyl phosphite, dicyclohexyl carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, N,N'-carbonyl diimidazole, dimethoxy-1,3,5-triazinylmethylmorpholine, O-(benzotriazol-1-yl)-N,N,N',N '-Tetramethyluronium tetrafluoroborate, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, (2,3- Dihydro-2-sulfanyl-3-benzo

Azolyl) phosphonic acid diphenyl ester and the like. The addition amount of the condensing agent is preferably 2 to 3 times mol relative to the tetracarboxylic acid diester.

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

Moreover, in the above reaction, by adding a Lewis acid as an additive, the reaction can proceed efficiently. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferred. The amount of Lewis acid added is preferably 0 to 1.0 times mol relative to the diamine component.

Even among the above-mentioned three kinds of synthetic methods of polyamide, in order to obtain a high-molecular-weight polyamide, the synthesis method of (1) or (2) above is particularly preferred.

The obtained solution of polyamide ester can be poured into a poorly soluble polymer (weak solvent) while fully stirring to precipitate the polymer. After several times of precipitation, washing with a weak solvent, and drying at room temperature or by heating, a purified polyamide ester powder can be obtained. The weak solvent is not particularly limited, and examples include water, methanol, ethanol, hexane, butyl cellosolve, acrylic Ketones, toluene, etc.

The weight average molecular weight of the polyamide is preferably 5,000 to 300,000, and more preferably 10,000 to 200,000. In addition, the number average molecular weight is preferably 2,500 to 150,000, and more preferably 5,000 to 100,000.

<Manufacturing Method of Polyimide>

Polyimines can be obtained by imidizing the above-mentioned polyamide acid or polyamide acid ester. As the method of the above-mentioned imidization, thermal imidization by heating or catalyst imidization using a catalyst is generally used. It is preferable to use a catalyst for imidization at a relatively low temperature because it is difficult to reduce the molecular weight of the obtained polyimid.

Catalytic imidization is achieved by stirring polyamide acid in the presence of a basic catalyst and acid anhydride in an organic solvent, or stirring polyamide acid in the presence of a basic catalyst. Can proceed. The reaction temperature at this time is -20 to 250°C, preferably 0 to 180°C. When the catalyst of polyimide is imidized, the imidization will accelerate if the reaction temperature is higher, but if it is too high, the molecular weight of the polyimide may decrease. The amount of the alkaline catalyst is 1 to 60 mol times, preferably 2 to 40 mol times, with respect to 1 mol of repeating unit of polyamide acid or polyamide ester. The amount of acid anhydride used for catalytic imidization of polyamide is 2-100 mol times, preferably 6-60 mol times, relative to 1 mol of repeating unit of polyamide. If the amount of the alkaline catalyst or acid anhydride is small, the reaction will not proceed sufficiently, and if the amount is too large, it will be difficult to completely remove it after the reaction.

As the base used in the imidization of polyamide acid as a catalyst The sexual catalyst can be exemplified by pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine is preferred because it has a moderate basicity that allows the reaction to proceed. As the basic catalyst used in the imidization of the catalyst of polyamide ester, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. can be exemplified. The base amine reaction is fast, so it is particularly preferred.

Moreover, as an acid anhydride used in the catalyst imidization of polyamic acid, acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. are mentioned. Among them, when acetic anhydride is used, since purification after the completion of the reaction will be easy, it is preferred. The organic solvent is not limited as long as it dissolves polyamide acid or polyamide acid ester. If this specific example is given, N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactone Amide, dimethyl sulfide, tetramethylurea, dimethyl sulfide, hexamethyl sulfide, γ-butyrolactone, γ-valerolactone, etc. The rate of imidization of the catalyst can be controlled by adjusting the amount of catalyst, reaction temperature and reaction time.

The produced polyimide can be obtained by throwing the above reaction solution into a poorly soluble polymer solvent (also referred to as a weak solvent), and recovering the produced precipitate. At this time, the weak solvent used is not particularly limited. Examples include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, water and the like. The polyimide that has been poured into a weak solvent and precipitated is filtered and then dried under normal pressure or reduced pressure at room temperature or by heating to be used as a powder. When the polyimide powder is dissolved in an organic solvent, and the reprecipitation operation is repeated 2 to 10 times, the polyimide can also be purified. If you return with a precipitation When the impurity cannot be completely removed by the collection operation, it is better to perform this purification step. The molecular weight of polyimide is not particularly limited. From the standpoint of ease of handling and stability of characteristics during film formation, the weight average molecular weight is preferably 2,000 to 200,000, and more preferably 4,000 to 50,000. .

<Terminal modification of polyimide, polyamide, or polyamide>

The terminal system of the polyimide or polyamide acid or polyamide ester used in the present invention may be modified. By using a terminal-modified polymer, solubility or coatability can be improved. The terminal modification system can be synthesized by adding an acid anhydride, a monoamine compound, an acid chloride, a monoisocyanate compound, and the like when synthesizing polyamide acid or polyamide acid ester.

<Solvent>

The solvent contained in the liquid crystal alignment agent of the present invention contains (A) γ-valerolactone, (B) γ-butyrolactone, and (C) a compound represented by the following formula (c).

In the above formula (c), R ¹ and R ³ are each independently a hydrogen atom, and the carbon number is 1 to 4, preferably 1 to 4 linear or branched alkyl group, or acetyl group. In addition, R ² is an alkanediyl group having 2 or 3 carbons. n is 1 or 2.

Preferred specific examples of R ¹ and R ³ in the above formula (c) include methyl, ethyl, n-propyl, isopropyl, n-butyl and the like. Specific examples of R ² include ethylene, trimethylene, and propylene.

As specific examples of the compound represented by the above formula (c), ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol , 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, butyl cellosolve acetic acid Ester, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2-( 2-ethoxy propoxy) propanol, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, etc. Among them, butyl cellosolve, butyl cellosolve acetate, or 1-butoxy-2-propanol is preferred.

Regarding the content of (A), (B), and (C) in the solvent contained in the liquid crystal alignment agent of the present invention, the γ-valerolactone of (A) contributes to the linearity of the coating film end Or dimensional stability, 20 to 75% by mass of the entire solvent is preferable, and 20 to 70% by mass is more preferable. (B) The γ-butyrolactone contributes to dimensional stability, so 20 to 80% by mass of the entire solvent is preferable, and 20 to 70% by mass is more preferable. The compound of (C) is preferably 5 to 50% by mass of the entire solvent, more preferably 5 to 40% by mass, and more preferably 10 to 40% by mass.

The specific and preferable content of (A), (B), and (C) is selected from (A) 20 to 75% by mass, and preferably 20 to 70% by mass so that the total amount becomes 100% by weight , (B) is 20 to 75% by mass, and preferably 20 to 70% by mass, (C) is 5 to 60% by mass, and more preferably 5 to 55% by mass.

The liquid crystal alignment agent of the present invention may also contain solvents other than the above (A), (B), and (C) (hereinafter also referred to as other solvents). As specific examples of other solvents, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-diethyl Methamide, N,N-dimethylacetamide, N-methylcaprolactone, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfide, dimethylsulfide , 1,3-dimethyl-imidazolinone, 3-methoxy-N,N-dimethylpropanamide, etc., these systems can also be used in combination of multiple types. Among them, the addition of N-methyl-2-pyrrolidone is preferable because the solubility of the polymer, the suppression of unevenness in the surface of the coating film, and the linearity of the end of the coating film will be further improved. In this case, the content of N-methyl-2-pyrrolidone is preferably 3 to 55% by mass, and more preferably 3 to 50% by mass relative to the entire solvent. The specific and preferable content is such that the total content is 100% by weight, the content of (A) is 20 to 70% by mass, the content of (B) is 20 to 70% by mass, and the content of (C) is 5 to 55% by mass, and the content of N-methyl-2-pyrrolidone is preferably 3 to 55% by mass.

<Liquid crystal alignment agent>

The liquid crystal alignment agent of the present invention is a composition containing the above-mentioned polymer and solvent, and the content (concentration) of the polymer can also be appropriately changed by setting the thickness of the liquid crystal alignment film to be formed, but it can be formed In terms of a uniform and flawless coating film, it is preferably 1 to 5% by mass, particularly preferably 2% to 4% by mass. The viscosity of the liquid crystal alignment agent of the present invention is preferably 5-20 mPa·s, particularly preferably 5-15 mPa·s in terms of inkjet coating points.

The content of the solvent in the liquid crystal alignment agent is selected in consideration of the aforementioned viscosity, and is preferably 95-99% by mass, particularly preferably 96-98% by mass. In this case, a concentrated polymer solution is prepared in advance, and the above-mentioned concentrated solution can also be diluted when used as a liquid crystal alignment agent. If the solvent content is higher than 99% by mass, the film thickness of the liquid crystal alignment film will become too small and a good liquid crystal alignment film cannot be obtained. If the solvent content is lower than 95% by mass, the nozzle The spitting out will become worse.

The liquid crystal alignment agent of the present invention may also contain various additives such as a silane coupling agent or a crosslinking agent. The silane coupling agent is added for the purpose of improving the adhesion between the substrate coated with the liquid crystal alignment agent and the liquid crystal alignment film formed thereon. The silane coupling agent can be added by well-known ones. If the addition amount of the silane coupling agent is too large, unreacted substances may have an adverse effect on the alignment of the liquid crystal. If it is too small, the effect on adhesion cannot be exhibited. Therefore, it is relative to the solid content of the polymer. 0.01 to 5.0% by weight is preferable, and 0.1 to 1.0% by weight is more preferable.

In addition, in order to efficiently perform the imidization of polyamide acid and polyamide acid ester when the liquid crystal alignment agent is used for firing the coating film, an imidization accelerator may be added. Well-known ones can be used as the imidization accelerator system.

<Liquid crystal alignment film>

The liquid crystal alignment agent of the present invention is coated on the substrate, and the liquid crystal alignment film can be obtained by drying and firing. The substrate on which the liquid crystal alignment agent of the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and plastics such as glass substrates, silicon nitride substrates, acrylic substrates, polycarbonate substrates, etc. can be used. Adhesive substrate, etc. Among them, it is preferable to use a substrate on which an ITO electrode or the like for liquid crystal driving is formed, from the viewpoint of simplification of the manufacturing process. In the case of a reflective liquid crystal display element, if it is a single-sided substrate, an opaque substrate such as a silicon wafer may also be used. In this case, a light-reflecting material such as aluminum may also be used for the electrode.

As the coating method of the liquid crystal alignment agent of the present invention, a spin coating method, a printing method, etc. can also be used, but the inkjet method is particularly preferred. When the liquid crystal alignment agent of the present invention is applied by the inkjet method to form a coating film, the uniformity of the film thickness in the coating surface or the linearity of the coating periphery can be obtained, and the coating can be suppressed It is a coating film with excellent size expansion and dimensional stability. In the present invention, a well-known inkjet device can be used, and well-known conditions can also be used for coating. For example, the devices or conditions disclosed in International Publication WO2014-024885 can be used.

The drying and firing steps after applying the liquid crystal alignment agent can be selected at any temperature and time, but usually in order to fully remove the organic solvent contained, it is dried at 40°C to 120°C for 1 minute to 10 minutes. Afterwards, it is fired at 150°C to 300°C for 5 minutes to 120 minutes. If the thickness of the coating film after firing is too thin, the reliability of the liquid crystal display element may decrease, so it is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

<Liquid crystal display element>

The obtained liquid crystal alignment film is aligned by rubbing treatment or photo-alignment treatment, or if it is used for vertical alignment, it does not require alignment treatment and can be used in liquid crystal display elements. Liquid crystal display element is used with liquid crystal Align the substrate of the film, and use a well-known method to fabricate a liquid crystal cell to form a device.

The method of manufacturing the liquid crystal cell is not particularly limited, but to give an example, for a pair of substrates on which the liquid crystal alignment film is formed, the surface of the liquid crystal alignment film is inside, and the sandwiching thickness is preferably 1-30 μm, and more preferably 2 After the spacers of ~10μm are installed, the surroundings are fixed with a sealant and liquid crystal is injected for sealing. There is no particular limitation on the method of enclosing the liquid crystal, and examples include a vacuum method in which liquid crystal is injected after pressure is reduced in the produced liquid crystal cell, and a drip method in which liquid crystal is dripped and sealed.

[Example]

The following examples are given to illustrate the present invention more specifically, but the present invention is not limited to them. The abbreviated symbols used hereafter and the measurement methods of each characteristic are as follows.

<Single>

1,3DMCBDE-Cl: Dimethyl 1,3-bis(chlorocarbonyl)-1,3-dimethylcyclobutane-2,4-dicarboxylate

BDA: 1,2,3,4-butane tetracarboxylic dianhydride, PMDA: pyromellitic anhydride

DADPA: 4,4’-Diaminodiphenylamine

Me-DADPA: N,N-bis(aminophenyl)-methylamine

DBA: 3,5-diaminobenzoic acid

p-PDA: p-phenylenediamine

TDA: 4-(2,5-Dioxytetrahydrofuran-3-yl)-1,2,3,4,-tetrahydronaphthalene-1,2,-dicarboxylic anhydride

<Solvent>

NMP: N-methyl-2-pyrrolidone, BCS: Butyl cellosolve

BCA: butyl cellosolve acetate, GBL: γ-butyrolactone

GVL: γ-valerolactone, DPM: dipropylene glycol monomethyl ether

NEP: N-ethyl-2-pyrrolidone, PB: 1-butoxy-2-propanol

<Viscosity>

The viscosity of the polymer solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a cone rotor TE-1 (1°34', R24), and a temperature of 25°C. .

<Molecular weight>

The molecular weight of the polymer is determined by GPC (normal temperature gel permeation chromatography) The measurement was carried out with an apparatus, and the number average molecular weight (hereinafter also referred to as Mn) and the weight average molecular weight (hereinafter also referred to as Mw) as converted values of polyethylene glycol and polyethylene oxide were calculated.

GPC device: manufactured by Shodex (GPC-101)

Column: manufactured by Shodex (KD803 and KD805 in series), column temperature: 50°C

Eluent: N,N-dimethylformamide (as an additive, lithium bromide-hydrate (LiBr‧H ₂ O) is 30mmol/L, phosphoric acid‧anhydrous crystal (o-phosphoric acid) is 30mmol/L, tetrahydrofuran (THF) ) Is 10ml/L), flow rate: 1.0ml/min

Standard samples for making calibration lines: Tosoh Corporation, TSK standard polyethylene oxide (weight average molecular weight (Mw) approximately 900,000, 150,000, 100,000, 30,000), and Polymer Laboratories polyethylene glycol (peak top molecular weight ( Mp) about 12,000, 4,000, 1,000). In order to avoid overlapping of the peaks, the measurement was performed on two samples of the four types of samples mixed with 900,000, 100,000, 12,000, and 1,000, and the three types of samples mixed with 150,000, 30,000, and 4,000.

<Iimidization rate>

Put 20 mg of polyimide powder into the NMR sample tube, add 0.53 mL of deuterated dimethyl sulfide (DMSO-d6 and 0.05% by mass TMS (tetramethylsilane) mixture), and completely dissolve it. The solution was passed through an NMR measuring device (JNM-ECA500) manufactured by Japan Electronics Datum Corporation To measure 500MHz proton NMR.

The rate of imidization is based on the proton peak from the unchanged structure before and after imidization, and can be obtained by the following formula.

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

In the above formula, x is the cumulative value of proton peaks derived from the NH group of polyamide, y is the cumulative value of reference proton peaks, and α-based polyamide (with an imidization rate of 0%) is relative to one polyamide The ratio of the number of base protons of the NH protons of amide acid.

(Synthesis example 1)

In a separable flask with a stirring device and a 10L (liter) nitrogen introduction tube, measure 114.59g (1.06mol) of p-phenylenediamine and 44.68g (0.12mol) of DA-A, and add 2972g of NMP and 210.1g of pyridine. (2.66mol) and then dissolve it. Next, while stirring this solution, 1,3DMCBDE-Cl 359.85 and (1.11 mol) were added, and it was made to react under water cooling for 4 hours. 500 g of GBL was added to the obtained polyamide acid solution and diluted. While stirring the solution, it was poured into 19103ml isopropanol, and the white precipitate was filtered to obtain the precipitated white precipitate. Then, 9551ml isopropanol was used to wash it in 5 times, and the white polyamide acid was obtained by drying. Ester resin powder (PWD-1). The molecular weight of this polyamide ester is Mn=5,182 and Mw=30,115.

The polyamide resin powder (PWD-1) obtained above is dissolved in GBL to obtain a polyamide resin solution (PAE-1) having a solid content of 10% by mass.

(Synthesis example 2)

In a 100 mL four-necked flask with a stirring device and a nitrogen introduction tube, weigh 1.30 g (12.0 mmol) of p-phenylenediamine and 3.01 g (7.99 mmol) of DA-B, and add 36.72 g of NMP and 29.38 g of GBL. Dissolve by adding nitrogen while stirring. While stirring the diamine solution, 5.70 g (19.0 mmol) of TDA was added, and NMP was added so that the solid content concentration was 12% by weight, and after stirring at room temperature for 24 hours, a polyamide acid solution ( PAA-1). The viscosity of the polyamic acid solution at a temperature of 25℃ is 285mPa‧s. In addition, the molecular weight of the polyamide acid is Mn=8,042 and Mw=18,958.

(Synthesis example 3)

In a four-necked flask equipped with a stirring device and a 100 ml nitrogen introduction tube, 50 g of the obtained polyamide acid solution (PAA-1) was taken out, 16.67 g of NMP was added, and the mixture was stirred for 30 minutes. Next, 3.86 g of acetic anhydride and 1.0 g of pyridine were added, and it was heated at 60°C for 3 hours to perform chemical imidization. While stirring the resultant reaction liquid, it was poured into 321 ml of methanol, and the deposited precipitate was collected by filtration, and then washed with 321 ml of methanol in three portions. By drying the obtained resin powder at 60°C for 12 hours, a polyimide resin powder can be obtained. The polyimide resin powder had an imidization rate of 86%, a molecular weight of Mn=6,920, and Mw=12,721.

The polyimide resin powder obtained above is dissolved in GBL to obtain a polyimide solution (SPI-1) with a solid concentration of 10% by mass.

(Synthesis example 4)

In a 200mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh out 1.10g (7.2mmol) of DBA and 6.14g (28.8mmol) of Me-DADPA, add 15.0g of NMP and 42.0g of GBL, while feeding nitrogen Stir to dissolve. While stirring the diamine solution, 6.42 g (32.4 mmol) of BDA, 0.62 g (2.8 mmol) of PMDA, and 18.0 g of GBL were added. After stirring at room temperature for 24 hours, a solid content concentration of 16% by mass and NMP were obtained. /GBL=2/8 polyamide acid solution (PAA-2). The viscosity of the polyamide acid solution at a temperature of 25°C is 380.5mPa‧s. In addition, the molecular weight of the obtained polyamide acid was Mn=7,048 and Mw=16,664.

(Example 1)

In a 200 ml sample tube with a stir bar, weigh 10.4 g of the polyamide acid solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4 After adding 3.2 g of NMP, 47.4 g of GBL, 19.5 g of GVL, and 9.7 g of BCA, stirring with a magnetic stirrer for 30 minutes can obtain the liquid crystal alignment agent (A-1).

(Example 2)

In a 200 ml sample tube containing a stir bar, weigh 10.4 g of the polyamide solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4 g, add NMP 3.2g, GBL After 27.0 g, GVL 40.0 g, and BCA 9.7 g, it was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-2).

(Example 3)

In a 200 ml sample tube containing a stir bar, weigh 10.4 g of the polyamide solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4 g, after adding 2.3 g of NMP, 7.5 g of GBL, 60.4 g of GVL, and 9.7 g of BCA, stirring with a magnetic stirrer for 30 minutes can obtain a liquid crystal alignment agent (A-3).

(Example 4)

In a 200 ml sample tube containing a stir bar, weigh 10.4 g of the polyamide solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4 g, after adding 2.3 g of NMP, 32.8 g of GBL, 19.5 g of GVL, and 25.3 g of BCS, stirring with a magnetic stirrer for 30 minutes can obtain a liquid crystal alignment agent (A-4).

(Example 5)

After adding 26.0 g of the polyimide solution (SPI-1) obtained in Synthesis Example 3, 4.9 g of NMP, 39.9 g of GBL, 19.5 g of GVL, and 9.7 g of BCA into a 200 ml sample tube with a stir bar, The liquid crystal alignment agent (A-5) can be obtained by stirring with a magnetic stirrer for 30 minutes.

(Example 6)

In a 200ml sample tube with a stir bar, take out 26.0g of the polyamide ester solution (PAE-1) obtained in Synthesis Example 1, add 44.8g of GBL, 19.5g of GVL, and 9.7g of BCA, and stir with magnetic The liquid crystal alignment agent (A-6) can be obtained by stirring for 30 minutes.

(Example 7)

In a 200 ml sample tube with a stir bar, weigh 10.4 g of the polyamide acid solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4, After adding NMP 1.6g, NEP 1.6g, GBL 47.4g, GVL 19.5g, and BCA 9.7g, it was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-7).

(Example 8)

In a 200 ml sample tube with a stir bar, weigh 10.4 g of the polyamide acid solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4, After adding 3.2 g of NMP, 47.4 g of GBL, 19.5 g of GVL, 4.9 g of BCA, and 4.9 g of PB, it was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (A-8).

(Comparative example 1)

In a 200 ml sample tube with a stir bar, weigh 2.6 g of the polyamide resin powder (PWD-1) obtained in Synthesis Example 1, add 87.7 g of GVL and 9.7 g of BCS, and stir with a magnetic stirrer After being dissolved, the liquid crystal alignment agent (B-1) can be obtained.

(Comparative example 2)

In a 200 ml sample tube containing a stir bar, weigh 10.4 g of the polyamide solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4 g, after adding 3.2 g of NMP, 66.9 g of GBL, and 9.7 g of BCS, stirring with a magnetic stirrer for 30 minutes can obtain a liquid crystal alignment agent (B-2).

(Comparative example 3)

Take out 10.4 g of the polyamide acid solution (PAE-1) obtained in Synthesis Example 1 and 9.8 g of the polyamide acid solution (PAA-2) obtained in Synthesis Example 4 into a 200 ml sample tube containing a stir bar. After adding 3.2 g of NMP, 71.5 g of GBL, and 4.9 g of DPM, stirring with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (B-3).

[Method of Formation and Evaluation of Coating Film]

After filtering the liquid crystal alignment agent with a membrane filter with a pore size of 1.0 μm, the substrate was coated by an inkjet method using the following equipment and conditions, and then the following preliminary drying and main firing were performed to form a coating film.

Inkjet coating device: HIS-200-1H (manufactured by Hitachi Plant Technologies)

Coating conditions: resolution 15μm, step speed 40mm/sec, frequency 2000Hz, pulse width 9.6μsec, droplet volume 42pl, pitch width 80μm, pitch length 141μm, applied voltage: 15V, nozzle interval 0.5mm

Substrate: A glass substrate with a size of 100 mm long x 100 mm wide and with ITO electrodes attached to the entire surface on one side

Coating area: on the ITO electrode surface of the substrate, use a rectangular area with a size of 72mm long x 80mm wide for coating

Placement time from the end of coating to preliminary drying: 60 seconds

Preliminary drying: 45℃/2 minutes (hot plate)

Full firing: 230°C/30 minutes (IR oven)

<Method of evaluating dimensional stability>

Using a vernier caliper to measure the longitudinal width and lateral width of the coating film obtained above, the difference of length 100mm×width 72×80mm from the set size can be obtained, and the average value is calculated as the "expansion width".

<Method of evaluating in-plane uniformity>

Observe the in-plane of the coating film obtained above by visual inspection and an optical microscope. If there is no orange peel-like unevenness, linear unevenness, film thickness unevenness, etc., the in-plane is uniform as "A". Observe by microscope Or visual observation, the unevenness as mentioned above can be identified as "B".

<Evaluation method of end straightness>

The end of the coating film obtained above was observed with an optical microscope. The shape of the coating film end was regarded as "A", and the shape of the coating film end was "B".

[evaluation result]

Table 1 below shows the evaluation results of the liquid crystal alignment agents obtained in Examples 1 to 6 and Comparative Examples 1 to 4.

[Industrial Utilization]

The liquid crystal alignment agent of the present invention can provide a liquid crystal display element with high reliability and suppressed defects such as display unevenness, so it can be used for TN, STN, IPS, FFS, VA (including MVA (Multi domain Vertical Alignment), optical vertical alignment, PSA (Polymer Sustained Alignment, etc.) are in the manufacturing of liquid crystal display elements in a wide range of drive modes.

However, all the contents of the specification, scope of patent claims, drawings, and abstract of Japanese Patent Application No. 2015-025606 filed on February 12, 2015 are cited here as the disclosure content of the specification of the present invention.

Claims (10)

A liquid crystal alignment agent containing at least one polymer selected from the group consisting of polyamide acid, polyamide ester, and polyimide, and a liquid crystal alignment agent with a solvent, characterized by the aforementioned solvent system Contains (A) γ-valerolactone, (B) γ-butyrolactone, and (C) a compound represented by the following formula (c),

(In the formula, R ¹ and R ³ are each independently a hydrogen atom, an alkyl group with 1 to 4 carbons, or an acetyl group, R ² is an alkanediyl group with 2 or 3 carbons, and n is 1 or 2). The liquid crystal alignment agent of claim 1, wherein the content of (A) is 20 to 75% by mass of the entire solvent. The liquid crystal alignment agent of claim 1, wherein the content of (A) is 20 to 75% by mass, the content of (B) is 20 to 75% by mass, and the content of (C) relative to the total solvent It is 5-60% by mass. The liquid crystal alignment agent according to any one of claims 1 to 3, wherein the solvent further contains N-methyl-2-pyrrolidone. The liquid crystal alignment agent of claim 4, wherein, relative to the total solvent, the content of (A) is 20 to 70% by mass, the content of (B) is 20 to 70% by mass, and the content of (C) is It is 5 to 55% by mass, and the content of N-methyl-2-pyrrolidone is 3 to 55% by mass. Such as the liquid crystal alignment agent of claim 1, wherein the polymer content It is 1~5 mass%. The liquid crystal alignment agent of claim 1, which is used to coat a substrate by an inkjet method. A liquid crystal alignment film characterized by being obtained from the liquid crystal alignment agent of any one of claims 1-7. A method for manufacturing a liquid crystal alignment film, characterized in that the liquid crystal alignment agent of any one of claims 1 to 6 is coated by an inkjet method. A liquid crystal display element characterized by being provided with the liquid crystal alignment film of claim 8.