WO2012056815A1

WO2012056815A1 - Process for producing liquid crystal alignment film, and liquid crystal display element

Info

Publication number: WO2012056815A1
Application number: PCT/JP2011/070495
Authority: WO
Inventors: 林　英治; 宏司平澤
Original assignee: Jsr株式会社
Priority date: 2010-10-28
Filing date: 2011-09-08
Publication date: 2012-05-03
Also published as: JPWO2012056815A1; TWI510528B; JP5741593B2; TW201221561A; KR101418465B1; KR20130020692A

Abstract

Provided are: a process for producing a liquid crystal alignment film, in which a heating procedure in the formation of the liquid crystal alignment film can be carried out at a relatively low temperature; and a liquid crystal display element. The present invention provides a process for producing a liquid crystal alignment film using a liquid crystal aligning agent that comprises at least one polymer selected from the group consisting of a polyamic acid and a polyimide and a solvent capable of solubilizing the polymer, wherein the process comprises: an application step of applying the liquid crystal aligning agent onto a substrate; a contact step of bringing the liquid crystal aligning agent that has been applied on the substrate into contact with a liquid which is compatible with the solvent and has a lower boiling point than that of the solvent and in which the polymer is poorly soluble or insoluble; and a film formation step of, subsequent to the contact step, heating the liquid crystal aligning agent on the substrate to form a coating film on the substrate.

Description

Method for producing liquid crystal alignment film and liquid crystal display element

The present invention relates to a method for producing a liquid crystal alignment film and a liquid crystal display element, and more specifically, to form a liquid crystal alignment film on a substrate by removing the solvent in the liquid crystal alignment agent applied on the substrate by heating. The present invention relates to a preferred method for producing a liquid crystal alignment film, and a liquid crystal display device comprising a liquid crystal alignment film produced by the production method.

Conventionally, as a liquid crystal display element, a horizontal alignment type liquid crystal display element such as a TN (Twisted Nematic) type or an IPS (In-Plane Switching) type and a vertical alignment type liquid crystal display element such as a VA (Vertical Alignment) type are known. . In these liquid crystal display elements, alignment control of liquid crystal molecules is performed by a liquid crystal alignment film formed on a substrate. In general, a liquid crystal alignment film is formed by applying a liquid crystal alignment agent in which polyimide or polyamic acid is dissolved in a solvent such as N-methyl-2-pyrrolidone (NMP) or γ-butyrolactone to the surface of the substrate. It can be obtained by heating. (For example, refer to Patent Document 1 and Patent Document 2).

Japanese Patent Laid-Open No. 9-241646 JP 2010-156934 A

By the way, generally a solvent that can dissolve polyimide or polyamic acid is a high boiling point solvent such as NMP or γ-butyrolactone, and when a coating film is formed on a substrate using a liquid crystal aligning agent containing these solvents, It is necessary to heat the coated surface at a relatively high temperature (for example, 200 ° C.). Therefore, for example, in a color liquid crystal display element, it may be considered that inconveniences such as discoloration of a dye contained in the color filter occur due to heat at the time of forming the liquid crystal alignment film. In addition, since high-temperature heat treatment is required when forming the liquid crystal alignment film, it may be considered that application to, for example, a plastic substrate is limited. On the other hand, when heating is performed at a low temperature in order to suppress discoloration of the dye, the solvent remains in the liquid crystal alignment film, and the voltage holding ratio in the formed liquid crystal alignment film is affected by the residual solvent. There is a risk that inconveniences such as lowering may occur.

Furthermore, if a coating film can be formed at a low temperature, it is possible to reduce the total amount of heat in the manufacturing process, and as a result, it is possible to reduce CO ₂ emissions and reduce costs. Also from such a viewpoint, it is desired to realize coating film formation at a low temperature.

The present invention has been made in view of the above-described problems, and can perform heating at the time of forming a liquid crystal alignment film at a relatively low temperature and can obtain a liquid crystal alignment film having good voltage holding characteristics even by low-temperature heating. The main object is to provide a method for producing a film and a liquid crystal display device comprising a liquid crystal alignment film produced by the production method.

The present invention employs the following means to achieve the above object.

That is, the method for producing a liquid crystal alignment film of the present invention uses a liquid crystal alignment agent containing at least one polymer selected from the group consisting of a polyamic acid and a polyimide, and a solvent soluble in the polymer. A method for producing a film, wherein the liquid crystal aligning agent is applied on a substrate, and the liquid crystal aligning agent applied on the substrate is compatible with the solvent and has a lower boiling point than the solvent. And a contact step of contacting a liquid which is poorly soluble or insoluble with respect to the polymer, and a film that forms a coating film on the substrate by heating the liquid crystal aligning agent on the substrate after the contact step. And a forming step.

According to the present invention, a liquid compatible with a solvent capable of dissolving polyamic acid or polyimide (first solvent) is brought into contact with a liquid crystal aligning agent applied on a substrate before heating for forming a coating film. . Thereby, before the heating, the quantity of the 1st solvent contained in the liquid crystal aligning agent on a board | substrate can be decreased as much as possible. Further, since the liquid used in the contact step has a boiling point lower than that of the first solvent, it can be evaporated by heating at a lower temperature than that of the first solvent. Therefore, even when heating for film formation is performed at a relatively low temperature, the remaining amount of the solvent in the formed liquid crystal alignment film can be reduced as much as possible. As a result, a liquid crystal alignment film having good voltage holding characteristics can be obtained.

Further, by using a liquid that is poorly soluble or insoluble in polyamic acid or polyimide as the liquid, mixing between the liquid crystal aligning agent and the liquid is suppressed, and the film thickness of the formed coating film is improved. can do. As such a liquid, it is preferable to use at least one selected from the group consisting of water, alcohols having 1 to 5 carbon atoms, ketones having 3 to 5 carbon atoms, and acetonitrile.

The present invention may include a preheating step of heating the liquid crystal aligning agent on the substrate at a temperature lower than the heating temperature in the film forming step after the coating step and before the contacting step. . When removing the solvent, it may be performed by two-stage heating. At this time, the previous heating is performed at a relatively low temperature to prevent the liquid crystal aligning agent from dripping on the substrate, and the subsequent heating is performed at a relatively high temperature. In some cases, a coating film may be formed. In such a configuration, by providing the contact step between the previous heating and the subsequent heating, the heating temperature during the subsequent heating can be made relatively low. Moreover, it is suitable also in the point which can make the influence on the coating film of the said liquid smaller.

In the present invention, the film forming step may be a step of heating the liquid crystal aligning agent on the substrate under atmospheric pressure. In the present manufacturing method, since the contact step is provided before heating for film formation, the heating temperature is kept relatively low even when the liquid crystal aligning agent is heated on the substrate at atmospheric pressure. In addition, the residual amount of the solvent in the formed liquid crystal alignment film can be minimized.

In the present invention, the film forming step may be a step of heating the liquid crystal aligning agent on the substrate under reduced pressure. By doing so, the heating temperature can be further lowered in the heating for film formation.

Furthermore, according to the present invention, there is provided a liquid crystal display device comprising a liquid crystal alignment film manufactured by the method for manufacturing a liquid crystal alignment film described above.

The manufacturing method of the liquid crystal aligning film of this invention includes the process of forming the coating film used as a liquid crystal aligning film on a board | substrate by apply | coating a liquid crystal aligning agent on a board | substrate, and then heating the coating-film surface. Specifically, it is preferable that the following steps (1) to (5) are included.

[Step (1): Preparation step]
This step is a step of preparing a liquid crystal aligning agent for forming a liquid crystal alignment film on the substrate. As the liquid crystal aligning agent, in a solvent, at least one polymer selected from the group consisting of polyamic acid and polyimide (hereinafter also referred to as a specific polymer) and other additives optionally blended as necessary. A composition dissolved in is used.

<Polyamic acid>
The polyamic acid contained in the liquid crystal aligning agent in this invention can be obtained by making tetracarboxylic dianhydride and diamine react.

(Tetracarboxylic dianhydride)
Examples of tetracarboxylic dianhydrides for synthesizing polyamic acid in the present invention include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides and the like. Can be mentioned.

Specifically, examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride. Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 1,3, 3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4 5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2 .1] Octane-2,4-dione-6-spiro-3 ′-(tetrahydrofuran-2 ′, 5′-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl- 3-Cyclohexene-1,2-dica Boric anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, bicyclo [3,3,0] octane-2,4,6,8- And tetracarboxylic dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride. it can. In addition, aliphatic tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides described in JP 2010-97188 A, other than those described above, can be used.

Specific examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, and other aromatic tetracarboxylic dianhydrides described in JP 2010-97188 A Of these, those other than the above can be used.

In addition, said aliphatic, alicyclic, and aromatic tetracarboxylic dianhydride can be used individually by 1 type or in combination of 2 or more types.

(Diamine)
Examples of the diamine for synthesizing the polyamic acid in the present invention include aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, and the like. Specific examples thereof include aliphatic diamines such as 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine and the like;
Examples of alicyclic diamines include 1,4-diaminocyclohexane, 4,4′-methylenebis (cyclohexylamine), 1,3-bis (aminomethyl) cyclohexane, and the like;

Examples of aromatic diamines include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4-aminophenyl-4′-aminobenzoate, 3,3′-dimethyl-4-aminophenyl-4′-aminobenzoate, 3,3 ′, 5,5′-tetramethyl-4-aminophenyl-4′-aminobenzoate, 3-methyl-4-aminophenyl-4′-aminobenzoate, 4,4′-diaminodiphenylmethane, 4,4 '-Diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2, 7-diaminofluorene, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) fe Ru] propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoro Propane, 4,4 '-(p-phenylenediisopropylidene) bisaniline, 4,4'-(m-phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4,4'- Bis (4-aminophenoxy) biphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3, 6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole N, N′-bis (4-aminophenyl) -benzidine, N, N′-bis (4-aminophenyl) -N, N′-dimethylbenzidine, 1,4-bis- (4-aminophenyl)- Piperazine, 3,5-diaminobenzoic acid, dodecanoxy-2,4-diaminobenzene, tetradecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2, 4-diaminobenzene, dodecanoxy-2,5-diaminobenzene, tetradecanoxy-2,5-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, hexadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, Cholestanyloxy-3,5-diaminobenze Cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, 3,5-diaminobenzoic acid Cholestenyl, Lanostanyl 3,5-diaminobenzoate, 3- (3,5-diaminobenzoyloxy) cholestane, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 4- (4′-trifluoromethylbenzoyloxy) cyclohexyl-3,5-diaminobenzoate, 1,1-bis (4-((Aminophenyl) methyl) phenyl) -4-butylcyclo Hexane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-heptylcyclohexane, 1,1-bis (4-((aminophenoxy) methyl) phenyl) -4-heptylcyclohexane, 1-bis (4-((aminophenyl) methyl) phenyl) -4- (4-heptylcyclohexyl) cyclohexane, 2,4-diamino-N, N-diallylaniline, 4-aminobenzylamine, 3-aminobenzylamine 1- (2,4-diaminophenyl) piperazine-4-carboxylic acid, 4- (morpholin-4-yl) benzene-1,3-diamine, 1,3-bis (N- (4-aminophenyl) piperidinyl ) Propane, α-amino-ω-aminophenylalkylene, and the following formula (A-1)

(In the formula (A-1), X ^I and X ^II are each a single bond, —O—, —COO— or —OCO—, and R ^I is a methylene group or an alkylene group having 2 or 3 carbon atoms. A is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and n is 0 or 1. provided that a and b are 0 at the same time. No.)
A compound represented by:

Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, and other diamines described in JP 2010-97188 A except for the above. Can be used.

Examples of the divalent group represented by “—X ^I — (R ^I —X ^II ) _n —” in the above formula (A-1) include a methylene group, an alkylene group having 2 or 3 carbon atoms, ^* —O— , ^* —COO— or ^* —O—CH ₂ CH ₂ —O— (wherein a bond marked with “*” is bonded to a diaminophenyl group). Specific examples of the group “—C _c H _{2c + 1} ” include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, and n-octyl group. N-nonyl group, n-decyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group And n-eicosyl group. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position with respect to the other groups.

Specific examples of the compound represented by the formula (A-1) include compounds represented by the following formulas (A-1-1) to (A-1-3).

(Synthesis of polyamic acid)
The ratio of the tetracarboxylic dianhydride and the diamine used for the polyamic acid synthesis reaction is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 with respect to 1 equivalent of the amino group of the diamine. A ratio of equivalents is preferable, and a ratio of 0.3 to 1.2 equivalents is more preferable. The synthesis reaction of polyamic acid is preferably performed in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., more preferably 0 to 100 ° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

(Organic solvent)
Examples of the organic solvent used for the synthesis of the polyamic acid include a solvent (first solvent) in which the specific polymer is soluble. For example, polyamic acid such as an aprotic polar solvent or a phenolic solvent can be used. Good solvents can be mentioned. Specific examples of these first solvents include, for example, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ- Butyrolactone, tetramethylurea, hexamethylphosphortriamide and the like; Examples of the phenol solvent include m-cresol, xylenol, and halogenated phenol. Among these, from the viewpoint of solubility, an aprotic polar solvent is preferable, and NMP or γ-butyrolactone is more preferable. In addition, these can be used individually or in mixture of 2 or more types.

As the organic solvent, a solvent (second solvent) that has low solubility in the specific polymer or does not dissolve the specific polymer is used in combination with the first solvent as long as the specific polymer does not precipitate. Can do. Examples of the second solvent include poor solvents and non-solvents of polyamic acid, and specific examples include alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. More specifically, examples of the alcohol include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, and ethylene glycol monomethyl ether;
Examples of the ketone include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;

Examples of the ester include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate;
Examples of the ether include diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate. Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran and the like;
Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene and the like;
Examples of the hydrocarbon include hexane, heptane, octane, benzene, toluene, xylene, isoamylpropionate, isoamylisobutyrate, and diisopentyl ether.

The content ratio of the second solvent in the organic solvent is preferably 50% by weight or less, more preferably 40% by weight or less, based on the total amount of the first solvent and the second solvent. Preferably it is 30 weight% or less. The amount (a) of the organic solvent used is such that the total amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by weight based on the total amount (a + b) of the reaction solution. It is preferable that

As described above, a reaction solution obtained by dissolving polyamic acid is obtained. This reaction solution may be used for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution. Or you may use for preparation of a liquid crystal aligning agent, after refine | purifying the isolated polyamic acid. Isolation and purification of the polyamic acid can be performed according to known methods.

<Polyimide>
The polyimide in the present invention can be obtained by dehydrating and ring-closing and imidizing the synthesized polyamic acid. In this case, the reaction solution obtained by dissolving the polyamic acid may be used for the dehydration ring-closing reaction as it is, or the polyamic acid contained in the reaction solution may be isolated and then used for the dehydration ring-closing reaction. Alternatively, the isolated polyamic acid may be purified and then subjected to a dehydration ring closure reaction.

The polyimide in the present invention may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure possessed by the polyamic acid that is a precursor thereof, and by dehydrating and cyclizing only a part of the amic acid structure, A partially imidized product in which a structure and an imide ring structure coexist may be used. The imidation ratio of the polyimide in the present invention is preferably 30% or more, more preferably 50 to 99%, still more preferably 65 to 99%. This imidation ratio represents the ratio of the number of imide ring structures to the total of the number of amic acid structures of polyimide and the number of imide ring structures, expressed as a percentage. Here, a part of the imide ring may be an isoimide ring.

The polyamic acid is preferably dehydrated and closed by heating the polyamic acid, or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to the solution, and heating the solution as necessary. . Of these, the latter method is preferred.

In the method of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride can be used as the dehydrating agent. The amount of the dehydrating agent used is preferably 0.01 to 20 mol with respect to 1 mol of the amic acid structure of the polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of the organic solvent used in the dehydration ring-closing reaction include the organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. May be used for the preparation of a liquid crystal aligning agent, or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. These purification operations can be performed according to known methods.

(Solution viscosity of polymer)
The specific polymer obtained as described above preferably has a solution viscosity of 20 to 800 mPa · s, and a solution viscosity of 30 to 500 mPa · s, when this is a 10% by weight solution. It is more preferable that it has. The solution viscosity (mPa · s) of the specific polymer is a polymer solution having a concentration of 10% by weight prepared using a good solvent for the specific polymer (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). Is a value measured at 25 ° C. using an E-type viscometer.

<Other additives>
Although the liquid crystal aligning agent of this invention contains the said specific polymer, you may contain the other component as needed. Such other components include, for example, a compound having at least one epoxy group in the molecule (hereinafter, referred to as “improvement of mechanical strength in the liquid crystal alignment film” or “adhesion between the liquid crystal alignment film and the substrate”). "Epoxy compound").

Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6- Hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodi Enirumetan, N, N-diglycidyl - benzylamine, N, N-diglycidyl - aminomethyl cyclohexane, N, N-diglycidyl - cyclohexyl amine may be mentioned as preferred.

When these epoxy compounds are added to the liquid crystal aligning agent, the blending ratio is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the total of the polymers contained in the liquid crystal aligning agent. preferable.

In addition to the above epoxy compounds, other additives include, for example, polymers other than polyamic acid and polyimide, functional silane compounds, imidization accelerators, and the like.

<Solvent>
As a solvent used for the liquid crystal aligning agent in this invention, the solvent which can dissolve said specific polymer can be mentioned, Specifically, what was illustrated as said 1st solvent can be mentioned. Among these, an aprotic polar solvent is preferable, and NMP or γ-butyrolactone is more preferable. In addition, they can be used individually or in mixture of 2 or more types.

As the solvent, a solvent that has low solubility in the specific polymer or does not dissolve the specific polymer, specifically, those exemplified as the second solvent, the first solvent in the range where the specific polymer does not precipitate. It can be used in combination with a solvent. In this case, the content ratio of the second solvent in the solvent is preferably 50% by weight or less, more preferably 40% by weight or less, and still more preferably 30% by weight or less with respect to the whole solvent.

[Step (2): Application step]
This step is a step of applying the liquid crystal aligning agent on the substrate. Examples of the substrate to be used include glass such as float glass and soda glass; and a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly (alicyclic olefin). In the case of manufacturing a liquid crystal display element in which the operation mode of the liquid crystal display element is a TN type, STN type, or VA type, two substrates provided with a patterned transparent conductive film are used. As the transparent conductive film provided on one surface of the substrate, a NESA film (registered trademark of US PPG) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), etc. Can be used. Moreover, in order to obtain the patterned transparent conductive film, for example, a method of forming a pattern by photo-etching after forming a transparent conductive film without a pattern, and a method of using a mask having a desired pattern when forming the transparent conductive film And so on. On the other hand, when manufacturing an IPS liquid crystal display element, a substrate provided with a transparent conductive film patterned in a comb shape and a counter substrate provided with no conductive film are used.

<Application method>
The application method for applying the liquid crystal aligning agent on the substrate is not particularly limited, and for example, an offset printing method, a spin coating method, a roll coater method, and an ink jet printing method can be applied.

The solid content concentration of the liquid crystal aligning agent used when applying the liquid crystal aligning agent on the substrate (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is viscous and volatile. However, it is preferably in the range of 1 to 10% by weight. When the solid content concentration is less than 1% by weight, the film thickness of the coating film is too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by weight, it is difficult to obtain a good liquid crystal alignment film due to excessive film thickness, and the viscosity of the liquid crystal aligning agent may increase, resulting in poor coating characteristics. There is.

The particularly preferable solid content concentration range varies depending on the method used when applying the liquid crystal aligning agent to the substrate. For example, when the spin coating method is used, the solid content concentration is particularly preferably in the range of 1.5 to 4.5% by weight. In the case of the offset printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight, and thereby the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the ink jet printing method, it is particularly preferable that the solid content concentration is in the range of 1 to 5% by weight, and thereby the solution viscosity is in the range of 3 to 15 mPa · s.

Before applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound, You may give the pretreatment which apply | coats a functional titanium compound etc. previously.

[Step (3) provisional coating film forming step]
After the coating step, it is preferable to perform a treatment for reducing the amount of the solvent in the liquid crystal aligning agent on the surface of the liquid crystal aligning agent on the substrate for the purpose of preventing dripping. By this step, a part of the solvent in the liquid crystal aligning agent is removed, and a temporary coating film made of the liquid crystal aligning agent is formed on the substrate. The form of solvent removal is not particularly limited, and for example, natural drying, reduced pressure drying, heat drying or the like can be applied. Especially, the thing by the preheating (prebaking) shown below is preferable.

[Step (3-1): Preheating step]
The heating temperature for preheating the liquid crystal aligning agent coating surface may be any temperature that can evaporate the solvent to such an extent that dripping can be prevented. For example, the specific polymer is dissolved in the preparation of the liquid crystal aligning agent. The temperature may be lower than the boiling point of the solvent (first solvent) used in the above. Moreover, it is preferable that the heating temperature at this time is low temperature rather than the heating (process (5) mentioned later) for forming the coating film used as an orientation film. Specifically, the pre-baking temperature is preferably 30 to 150 ° C., more preferably 40 to 120 ° C., and further preferably 40 to 100 ° C. The prebake time is preferably 0.25 to 20 minutes, more preferably 0.5 to 10 minutes.

[Step (4): Contacting step]
In this step, a liquid crystal aligning agent applied on the substrate, preferably a temporary coating film made of the liquid crystal aligning agent formed by the preheating step is applied to a liquid compatible with the first solvent (hereinafter referred to as a specific liquid). It is also a step of contacting with. By this step, the solvent contained in the liquid crystal aligning agent on the substrate, particularly the first solvent can be extracted. In addition, when the contact with the specific liquid is performed on the temporary coating after the preheating, the solvent remaining in the temporary coating can be more suitably extracted, and the specific liquid and the liquid crystal alignment Mixing with the agent is further suppressed, and it becomes easy to ensure a sufficient film thickness in the coating film.

<Specific liquid>
The specific liquid in the present invention is compatible with the first solvent used for the purpose of solubilizing the specific polymer in the preparation of the liquid crystal aligning agent among those exemplified above as the second solvent. A solvent having a boiling point lower than that of the first solvent can be used. Specific examples of such a liquid include a single solvent such as water, an alcohol having 1 to 5 carbon atoms, a ketone having 3 to 5 carbon atoms, and acetonitrile, or a mixed solvent of two or more kinds. Among these, examples of the alcohol having 1 to 5 carbon atoms include methanol, ethanol, isopropanol, isobutanol, and isopentyl alcohol. Examples of the ketone having 3 to 5 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, And methyl isopropyl ketone. Among them, water, methanol, ethanol, isopropanol, acetone or methyl ethyl ketone is preferably a single solvent or a mixed solvent of two or more of them, and is a single solvent with water or at least one of methanol, ethanol and isopropanol and water. It is more preferable that it is a mixed solvent.

When a mixed solvent of alcohol and water is used as the specific liquid, the concentration of alcohol with respect to the entire specific liquid is preferably 5 to 55% by weight, and more preferably 10 to 50% by weight. When the content is 55% by weight or less, the flammability of the mixed solution can be suitably reduced. Further, if it is 10% by weight or more, the residual amount of the solvent in the liquid crystal alignment film can be further reduced, and a liquid crystal alignment film having good voltage holding characteristics even by low-temperature heating, which is the object of this patent, is obtained. It is significant to realize such things.

<Contact method>
A method for bringing the liquid crystal aligning agent and the specific liquid into contact with each other on the substrate is not particularly limited, and for example, a shower method, a spray method, a dip (immersion) method, a paddle (liquid accumulation) method, or the like can be applied. In contact with the specific liquid, a part of the surface of the liquid crystal aligning agent may be brought into contact with the specific liquid, but the entire surface of the liquid crystal aligning agent is preferably brought into contact with the specific liquid. At this time, in order to extract and remove the solvent in the liquid crystal aligning agent as much as possible, for example, a series of processes of supplying and contacting the specific liquid onto the substrate are performed a plurality of times, or if the dipping method is used, the specific liquid is stirred. Alternatively, shaking is also effective. The temperature at the time of contact with the specific liquid is preferably 10 to 50 ° C., more preferably 20 to 30 ° C. The contact time is preferably 5 seconds to 30 minutes, more preferably 5 seconds to 15 minutes. In addition, the usage-amount of the specific liquid in the case of contact with a liquid crystal aligning agent is suitably selected in consideration of the contact method etc. with a specific liquid.

[Step (5): Film formation step]
This step is a step of heating the application surface of the liquid crystal aligning agent on the substrate. By the heating (post-bake) in this step, the solvent remaining in the liquid crystal aligning agent applied on the substrate is almost removed, and a coating film that becomes a liquid crystal aligning film is formed on the substrate. Moreover, this process is also heat processing performed in order to thermally imidize the amic acid unit contained in a liquid crystal aligning agent as needed.

Regarding the post-bake conditions, specifically, the post-bake temperature is preferably 80 to 190 ° C, more preferably 120 to 180 ° C, and further preferably 140 to 180 ° C. The post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The first solvent generally has a high boiling point, but when heated in this step, the amount of the first solvent contained in the liquid crystal aligning agent on the substrate is reduced in advance by the contact step. In the case of carrying out the process, the residual solvent amount in the coating film can be sufficiently reduced. The film thickness of the coating film thus formed is preferably 30 nm to 150 nm, more preferably 30 nm to 120 nm.

The above heat treatment may be performed under atmospheric pressure (normal pressure) or under reduced pressure. Or after performing the pressure reduction process after the said contact process, you may implement said heat processing in the state returned to atmospheric pressure. When performing a pressure reduction process, it is preferable that the pressure during the pressure reduction process be equal to or lower than the saturated vapor pressure in the solvent having the highest saturated vapor pressure among the solvents contained in the liquid crystal aligning agent. Further, when a plurality of types of solvents are contained in the liquid crystal aligning agent, the pressure reducing operation may be performed in a plurality of stages in consideration of the difference between the saturated vapor pressures.

The method for producing a liquid crystal alignment film of the present invention may include, for example, the following step (6) as necessary in addition to the above steps (1) to (5).

[Step (6): rubbing treatment]
When manufacturing a TN, STN, or IPS type liquid crystal display element, the liquid crystal display element is wound with a cloth made of fibers such as nylon, rayon, and cotton, for example. A rubbing process that rubs in a certain direction with a roll is applied. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film.

Furthermore, with respect to the liquid crystal alignment film, a treatment for changing the pretilt angle of a part of the liquid crystal alignment film by irradiating a part of the liquid crystal alignment film with ultraviolet rays, or a resist film on a part of the liquid crystal alignment film surface After forming the film, the resist film may be removed after the rubbing treatment in a direction different from the previous rubbing treatment. By making the liquid crystal alignment film have different liquid crystal alignment ability for each region, it is possible to improve the visual field characteristics of the obtained liquid crystal display element.

In addition, when manufacturing a VA type liquid crystal display element, although the coating film formed as mentioned above can be used as a liquid crystal alignment film as it is, you may give said rubbing process.

[Liquid crystal display element]
The liquid crystal display element of this invention comprises the liquid crystal aligning film manufactured by the said manufacturing method, for example, can be manufactured by the following process (7).
[Step (7): Construction of liquid crystal display element]
In constructing a liquid crystal display element, first, with respect to a pair of substrates on which a liquid crystal alignment film is formed by the above manufacturing method, a gap (cell) is set so that the rubbing directions of the liquid crystal alignment films of the two substrates are orthogonal or antiparallel. It is arranged oppositely through a gap). Subsequently, the peripheral portions of the two substrates are bonded together using a sealant, and liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealant, and the injection hole is sealed to form a liquid crystal cell. . And a liquid crystal display element can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell so that the polarization direction thereof matches or is orthogonal to the rubbing direction of the liquid crystal alignment film formed on each substrate.

As the sealant, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.

Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable. For example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl. Cyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used. Further, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonate, cholesteryl carbonate, etc .; chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck) A ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used.

As a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film itself in which a polarizing film called an “H film” in which iodine is absorbed while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of can be mentioned.

The liquid crystal display element of the present invention can be effectively applied to various devices such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, various monitors. It can be used for a display device such as a liquid crystal television.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

The solution viscosity of the polymer in each of the following synthesis examples is a value measured at 25 ° C. using an E-type rotational viscometer. Moreover, the imidation ratio of polyimide was measured as follows.
[Imidation rate of polyimide]
The polyimide solution was poured into pure water, and the resulting precipitate was sufficiently dried at room temperature under reduced pressure, then dissolved in deuterated dimethyl sulfoxide, and ¹ H-NMR was measured at room temperature using tetramethylsilane as a reference substance. From the obtained ¹ H-NMR spectrum, the imidation ratio was determined by the formula shown by the following formula (1).
Imidation ratio (%) = (1−A ¹ / A ² × α) × 100 (1)
(In Formula (1), A ¹ is a peak area derived from protons of NH groups appearing near a chemical shift of 10 ppm, A ² is a peak area derived from other protons, and α is a precursor of a polymer (polyamic acid). The number ratio of other protons to one proton of NH group in)

[Preparation process]
<Synthesis of polymer>
(Synthesis Example 1)
110 g (0.50 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride as tetracarboxylic dianhydride, 43 g (0.40 mol) of p-phenylenediamine and 3- (3,5- Diaminobenzoyloxy) cholestane 52 g (0.10 mol) was dissolved in NMP 830 g and reacted at 60 ° C. for 6 hours. A small amount of the resulting polyamic acid solution was taken, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it was 60 mPa · s. Next, 1900 g of NMP was added to the obtained polyamic acid solution, 40 g of pyridine and 51 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with new NMP (pyridine and acetic anhydride used for the imidization reaction were removed from the system in this operation), and about 50% of the imidation ratio of polyimide was reduced. A solution (A-1) containing 15% by weight was obtained. A small amount of the obtained polyimide solution was taken, NMP was added, and the solution viscosity measured as a solution having a polyimide concentration of 10% by weight was 47 mPa · s.

(Synthesis Example 2)
110 g (0.50 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, 38 g (0.35 mol) of p-phenylenediamine as a diamine compound, 4,4′-diaminodiphenylmethane 20 g (0.1 mol) and 26 g (0.05 mol) of 3- (3,5-diaminobenzoyloxy) cholestane were dissolved in 800 g of NMP and reacted at 60 ° C. for 6 hours. A small amount of the resulting polyamic acid solution was taken, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it was 60 mPa · s. Next, 1800 g of NMP was added to the obtained polyamic acid solution, 80 g of pyridine and 100 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidization reaction, the solvent in the system was replaced with a new γ-butyrolactone (the pyridine and acetic anhydride used for the imidation reaction were removed from the system in this operation), and the polyimide with an imidation ratio of about 80% A solution (A-2) containing about 15 wt% was obtained. A small amount of the obtained polyimide solution was taken, and γ-butyrolactone was added to measure the solution viscosity as a solution having a polyimide concentration of 10% by weight. The solution viscosity was 87 mPa · s.

<Preparation of liquid crystal aligning agent>
(Liquid crystal aligning agent (1))
NMP and butyl cellosolve (BC) are added to the polyimide solution (A-1) obtained in Synthesis Example 1, and N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane is added as an epoxy compound. 10 parts by weight with respect to a total of 100 parts by weight of the polymer was added and stirred sufficiently to obtain a solution having a solvent composition of NMP: BC = 50: 50 (weight ratio) and a solid content concentration of 3.5% by weight. The solution was filtered using a filter having a pore diameter of 1 μm to prepare a liquid crystal aligning agent (1) as a coating solution.

(Liquid crystal aligning agent (2))
Γ-Butyrolactone (BL), NMP and BC are added to the polyimide solution (A-2) obtained in Synthesis Example 2, and N, N, N ′, N′-tetraglycidyl-4,4 ′ is added as an epoxy compound. -Add 10 parts by weight of diaminodiphenylmethane to 100 parts by weight of the total amount of polymer, stir well, solvent composition BL: NMP: BC = 30: 40: 30 (weight ratio), solid content concentration 3.5 weight % Solution. The solution was filtered using a filter having a pore diameter of 1 μm to prepare a liquid crystal aligning agent (2) as a coating solution.

[Coating process]
A glass substrate with a transparent electrode made of ITO is subjected to ultrasonic cleaning in order for 30 minutes each in an alkaline aqueous solution for glass cleaning and ultrapure water, and then washed with running water for 30 minutes with ultrapure water. After ultrasonic cleaning for 30 minutes in isopropanol, drying was performed in a 100 ° C. oven for 30 minutes. The substrate was further dehydrated by heating on a 200 ° C. hot plate for 1 minute, and then UV ozone cleaning was performed with a UV ozone cleaner (SEN LIGHT CORP., Model “PM9011 N-1”).

On the transparent electrode surface of the glass substrate with a transparent electrode immediately after the UV cleaning, each of the liquid crystal alignment agents (1) and (2) is 200 to 280 mg using an ink jet printing apparatus (manufactured by Shibaura Mechatronics). / Head · 10 seconds, 2,500 times / nozzle · second, 2 reciprocating coatings (4 times coating). By this application, a substrate in which a liquid crystal aligning agent was applied in the form of a regular square (10 cm × 10 cm) on a glass substrate was obtained.

[Preheating step (pre-baking)]
Each of the obtained glass substrates was heated on a hot plate at 100 ° C. for 10 minutes to remove a part of the solvent. As a result, pre-fired alignment films (1) and (2) having an average film thickness of 100 nm were obtained.

[Contact process (cleaning process)]
The prepared pre-fired alignment films (1) and (2) were each immersed in 500 mL of ultrapure water or 500 g of a 50 wt% / 50 wt% mixed solution of ultrapure water and ethanol at 25 ° C. for 10 minutes. Thereafter, the droplets on the alignment film surface were removed with an air knife or the like. As a result, water-washed alignment films (M-1) and (M-2) and water / ethanol mixed solution cleaning-treated alignment films (M-3) and (M-4) were obtained.

[Film formation process (post-bake)]
Each of the water-washed alignment films (M-1) and (M-2) and the water / ethanol mixed solution washing-treated alignment films (M-3) and (M-4) obtained as described above was heated at 150 ° C. or Heated at 180 ° C. The heating was performed under vacuum or normal pressure.
<Baking under vacuum>
Firing was performed using a vacuum firing apparatus capable of controlling the pressure reduction speed up to a constant pressure by inserting a slow bend valve in the middle of the exhaust passage using a pump having an exhaust capacity of 3200 liters / min. First, each of the cleaning-treated alignment films (M-1) to (M-4) is put in an apparatus and depressurized at 150 ° C. or 180 ° C. to 2.7 mmHg over 14 seconds. Fully opened and further depressurized to 0.5 mmHg over 21 seconds. It hold | maintained for 20 minutes in this state, Then, it returned to a normal pressure and obtained the liquid crystal aligning film on the glass substrate.

<Baking under normal pressure>
A clean oven was used as the baking apparatus. Each of the cleaning treatment alignment films (M-1) to (M-4) is baked at 150 ° C. or 180 ° C. under normal pressure for 20 minutes under a nitrogen stream to obtain a liquid crystal alignment film on a glass substrate. It was.

[Measurement and evaluation of solvent residue]
No. shown in Table 1 below. 1-No. The solvent residual amount was measured for the liquid crystal alignment film formed on the substrate under each of the 24 conditions. First, 10 substrates having a liquid crystal alignment film were cut into 1 cm × 8 cm, and post-baked by a headspace gas chromatogram analyzer consisting of JTD-505II manufactured by Nippon Analytical Chemical Industry, HP6890 manufactured by Hewlett Packard, and WJMS-Q1000GC K9 manufactured by JEOL. The residual amount of solvent was measured. Residual amount of solvent was quantitatively evaluated in terms of octadecane as a standard substance. The measurement results are shown in Table 1 below.

[Production of liquid crystal cell for evaluating voltage holding ratio]
No. shown in Table 1 below. 1-No. Prepare a pair (two) of substrates having alignment films formed under each of the 16 conditions, and then apply an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer edge of one of the pair of substrates. After coating, the adhesive was cured by overlapping and pressing so that the liquid crystal alignment film surfaces face each other. Next, a nematic liquid crystal (MLC-6608, manufactured by Merck & Co., Inc.) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an acrylic photo-curing adhesive. Thereby, evaluation cells of Examples 1 to 16 were obtained.

[Measurement and evaluation of voltage holding ratio]
A voltage of 5 V was applied to the obtained evaluation cells (No. 1 to No. 16) of Examples 1 to 16 with an application time of 60 microseconds and a span of 167 milliseconds, and 167 milliseconds after the application release. The voltage holding ratio was measured. As a measuring device, VHR-1 manufactured by Toyo Corporation was used. The case where the voltage holding ratio was 98% or more was evaluated as “good”, and the other cases were evaluated as “bad”. The results are shown in Table 1 below.

An evaluation cell was prepared by the same method as that for the cleaning-treated alignment films (M-1) to (M-4) except that the cleaning treatment was not performed. 17-No. 24 (comparative example). For these evaluation cells, the evaluation cell no. 1-No. The voltage holding ratio was measured by the same method as in No. 16, and the voltage holding characteristics were evaluated. The results are shown in Table 1 below.

As shown in Table 1, in the examples (No. 1 to No. 16) in which the cleaning treatment was performed before the post-baking, comparative examples (No. 17 to No. 16) in which the cleaning treatment was not performed before the post-baking. The amount of residual solvent in the liquid crystal alignment film was smaller than that of 24), which was about 0.6 to 0.7 of the residual amount of solvent in the comparative example. Further, when the amount of residual solvent was compared between the case where water was used as the cleaning liquid and the case where the mixed liquid of water / ethanol was used, the amount of residual solvent was almost the same or less when water was used.

In addition, as shown in Table 1, the evaluation cell numbers using the cleaning alignment films (M-1) to (M-4) are shown. 1-No. No. 16 (Example) showed good voltage holding characteristics when the post-bake temperature was 180 ° C. and 150 ° C. This result was observed in both cases where post-baking was performed under normal pressure or under vacuum. On the other hand, evaluation cell No. provided with the liquid crystal aligning film produced without performing the washing | cleaning process. 17-No. No. 24 (Comparative Example) had a low voltage holding ratio of less than 98% when the post-bake temperature was 180 ° C. and 150 ° C.

Claims

A method for producing a liquid crystal alignment film using a liquid crystal aligning agent containing at least one polymer selected from the group consisting of polyamic acid and polyimide, and a solvent soluble in the polymer,
An application step of applying the liquid crystal aligning agent on a substrate;
Contacting the liquid crystal aligning agent applied on the substrate with a liquid that is compatible with the solvent and has a lower boiling point than the solvent and is poorly soluble or insoluble in the polymer;
After the contacting step, a film forming step of forming a coating film on the substrate by heating the liquid crystal aligning agent on the substrate;
A method for producing a liquid crystal alignment film, comprising:
2. The liquid crystal alignment according to claim 1, further comprising a preheating step of heating the liquid crystal alignment agent on the substrate at a temperature lower than the heating temperature in the film forming step after the coating step and before the contact step. A method for producing a membrane.
3. The method for producing a liquid crystal alignment film according to claim 1, wherein the liquid is at least one selected from the group consisting of water, alcohol having 1 to 5 carbon atoms, ketone having 3 to 5 carbon atoms, and acetonitrile.
The method for producing a liquid crystal alignment film according to any one of claims 1 to 3, wherein the film forming step is a step of heating a liquid crystal alignment agent on the substrate under atmospheric pressure.
The method for producing a liquid crystal alignment film according to any one of claims 1 to 3, wherein the film forming step is a step of heating the liquid crystal alignment agent on the substrate under reduced pressure.
A liquid crystal display element comprising a liquid crystal alignment film manufactured by the method for manufacturing a liquid crystal alignment film according to any one of claims 1 to 5.