Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D179/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen, with or without oxygen, or carbon only, not provided for in groups C09D161/00 - C09D177/00
  • C09D179/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
  • C09D179/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/1042—Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/1075—Partially aromatic polyimides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/1075—Partially aromatic polyimides
  • C08G73/1078—Partially aromatic polyimides wholly aromatic in the diamino moiety
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
  • G02F1/133711—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by organic films, e.g. polymeric films
  • G02F1/133723—Polyimide, polyamide-imide
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2205/00—Polymer mixtures characterised by other features
  • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group

Definitions

• This liquid crystal alignment film is generally produced by performing a so-called “rubbing process” in which the surface of a polyimide film formed on a substrate with electrodes is rubbed against the surface with rayon or nylon cloth. Yes.
• a liquid crystal alignment film for VA Vertical Alignment: vertical alignment
• a photo alignment film that imparts anisotropy to the film surface by irradiating polarized UV and aligns the liquid crystal have attracted attention.
• a method of forming a polyimide film to be a liquid crystal alignment film on a substrate with electrodes using a liquid crystal alignment agent using a varnish prepared containing a polyimide precursor such as polyamic acid (also referred to as polyamic acid), A method of producing the coating film and imidizing on the substrate is known.
• a polyimide that has been imidized in advance is dissolved in a solvent to prepare a so-called solvent-soluble polyimide varnish, and a polyimide film is formed using a liquid crystal aligning agent using the polyimide varnish. is there.
• a method for solving such a problem a method of obtaining a liquid crystal aligning agent by blending a polyimide precursor with a varnish prepared by dissolving polyimide in a solvent has been proposed (for example, see Patent Document 1).
• a method of obtaining a liquid crystal aligning agent by blending polyimides having different imidization ratios has been proposed.
• These liquid crystal aligning agents form a polyimide film using phase separation to obtain a liquid crystal aligning film.
• the conventional liquid crystal aligning agent using phase separation is liable to cause a problem of whitening due to moisture absorption and precipitation of aggregates during printing on a substrate for forming a coating film.
• liquid crystal aligning agent which is prepared from a polyimide varnish, suppresses generation
• the present invention has the following gist.
• a method for preparing a polyimide varnish comprising imidizing each of the polyimide precursors in a solution containing two or more types of polyimide precursors, and dissolving and containing two or more types of polyimides.
• a liquid crystal display device comprising the liquid crystal alignment film according to (12) or (13).
• Patent Document 2 and Patent Document 3 conventionally, a liquid crystal aligning agent containing two or more types of polyimide is known, but a conventional polyimide varnish containing two or more types of polyimide is Separately prepare solutions containing two or more kinds of polyimide precursors, perform imidization separately in each solution, and then perform polyimide recovery and purification of the polyimide for each of the obtained polyimide solutions. . And each obtained polyimide is dissolved in a solvent, and two or more types of polyimide solutions corresponding to the number of types of polyimide are obtained.
• the two or more kinds of polyimides mean those having different structures of polyimide precursors as corresponding raw materials. That is, the raw material of the polyimide precursor, which is different from the type of tetracarboxylic acid dihydrate and diamine, and those composed of the same tetracarboxylic acid dihydrate and diamine combination, each having a different ratio It becomes another kind of polyimide precursor.
• the polyimide precursor is a polyamic acid and / or a polyamic acid ester.
• a particularly preferred polyimide precursor is polyamic acid.
• two or more kinds of polyimides or two or more kinds of polyimide precursors are usually two kinds, but depending on circumstances, three or more kinds or even four or more kinds may be used. .
• the method for preparing a polyimide varnish of the present invention In the method for preparing a polyimide varnish of the present invention, imidization and subsequent recovery and purification need only be performed once even if it contains two or more types of polyimide.
• the method for preparing the polyimide varnish of the present invention can improve the production efficiency as compared with the conventional method, and can reduce the amount of solvent and catalyst required for imidization.
• the preparation method of the polyimide varnish of the present invention has a great advantage in terms of manufacturing as compared with the conventional method.
• the raw material tetracarboxylic dianhydride or its derivative and diamine may be appropriately selected according to the polyimide varnish containing two or more types of polyimide to be produced. it can.
• a method for preparing a solution containing two or more kinds of polyimide precursors for two or more kinds of polyimides to be contained in a polyimide varnish, a solution containing a polyimide precursor corresponding to each is separately prepared, and the solutions are mixed with each other. Is possible.
• a solution containing a polyimide precursor corresponding to at least one of two or more types of polyimide to be contained in the polyimide varnish is prepared, and an isolated polyimide precursor corresponding to another polyimide is added to the solution. It is also possible to prepare a solution containing two or more types of polyimide precursors by dissolving them.
• a tetracarboxylic dianhydride having a desired structure or a derivative thereof is selected, and a diamine having a desired structure is selected correspondingly.
• they are reacted with each other in an appropriate solvent and polymerized to obtain a polyimide precursor such as polyamic acid having a desired structure in a solution state.
• a plurality of types of solutions containing polyimide precursors having different structures are obtained.
• the polyimide precursor is recovered from the solution, and after necessary purification and the like, the recovered polyimide precursor may be used for the preparation of the polyimide varnish.
• the polyimide precursor can be dissolved again in a desired solvent, and the resulting polyimide precursor solution can be used to prepare a polyimide varnish.
• tetracarboxylic dianhydride it is preferable to use tetracarboxylic dianhydride as the tetracarboxylic dianhydride having a desired structure or a derivative thereof.
• tetracarboxylic dianhydrides and diamines that can be selected and diamine will be specifically described below.
• the tetracarboxylic dianhydride to be reacted with the diamine is not particularly limited. Specific examples are given below.
• Examples of the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane.
• Tetracarboxylic dianhydride 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetra Carboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic Acid dianhydride, 3,4-dicarboxy-1-cyclohexylsuccinic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, 1, , 3,4-Butanetetracarboxylic dianhydride, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclo
• Aromatic tetracarboxylic dianhydrides can also be used.
• An aromatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride containing an aromatic ring.
• the aromatic tetracarboxylic dianhydride can be used in addition to the tetracarboxylic dianhydride having the alicyclic structure or the aliphatic structure. If aromatic tetracarboxylic dianhydride is used in this way, the liquid crystal alignment film formed from the liquid crystal aligning agent using the resulting polyimide varnish will improve the liquid crystal alignment and reduce the accumulated charge of the liquid crystal display element. Can be made.
• aromatic tetracarboxylic dianhydrides examples include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 2,2 ′, 3,3′-biphenyl.
• Tetracarboxylic dianhydride 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,3 ′, 4'-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalene Examples thereof include tetracarboxylic dianhydride and 2,3,6,7-naphthalenetetracarboxylic dianhydride.
• tetracarboxylic dianhydrides are 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene.
• CBDA 1,2,3,4-cyclobutanetetracarboxylic dianhydride
• TDA succinic dianhydride
• PMDA pyromellitic dianhydride
• TCA 2,3,5-tricarboxycyclopentylacetic acid dianhydride
• TDA succinic dianhydride
• PMDA pyromellitic dianhydride
• TCA 2,3,5-tricarboxycyclopentylacetic acid dianhydride
• the polyamic acid obtained by using these is converted into polyimide, and is particularly suitable for realizing a polyimide varnish that has excellent printability and suppresses the formation of aggregates when a coating film is formed on the substrate.
• Tetracarboxylic dianhydride is a liquid crystal alignment film formed from a liquid crystal aligning agent that uses the polyimide varnish obtained while considering the printability of the resulting polyimide varnish and the effect of suppressing the formation of aggregates during coating formation.
• a liquid crystal aligning agent that uses the polyimide varnish obtained while considering the printability of the resulting polyimide varnish and the effect of suppressing the formation of aggregates during coating formation.
• one kind or two or more kinds can be used in combination.
• tetracarboxylic dianhydrides When two or more kinds of tetracarboxylic dianhydrides are used in combination to form a single polyimide precursor, the above-described 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 3, 4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride (TDA), pyromellitic dianhydride (PMDA), 2,3,5-tricarboxycyclopentyl acetate dianhydride
• TDA 4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride
• PMDA pyromellitic dianhydride
• TCA 1,2,3,4-cyclobutanetetracarboxylic dianhydride
• TDA 4-dicarboxy-1,2,3,4-tetra
• a tetracarboxylic acid dialkyl ester that is a derivative of tetracarboxylic dianhydride in order to obtain a polyamic acid ester that is a polyimide precursor, a tetracarboxylic acid dialkyl ester that is a derivative of tetracarboxylic dianhydride can be used.
• the tetracarboxylic acid dialkyl ester that can be used is not particularly limited. Specific examples are given below.
• aliphatic tetracarboxylic acid diester examples include 1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dialkyl ester, 1,2 , 3,4-cyclopentanetetracarboxylic acid dialkyl ester, 2,3,4,5-tetrahydrofurantetracarboxylic acid dialkyl ester, 1,2,4,5-cyclohexanetetracarboxylic acid dialkyl ester, 3,4-dicarboxy- 1-cyclohexyl succinic acid dialkyl ester, 3,4-dicarboxy 1,2,3,4-tetrahydro-1-naphthalene
• aromatic tetracarboxylic acid dialkyl ester examples include pyromellitic acid dialkyl ester, 3,3 ′, 4,4′-biphenyltetracarboxylic acid dialkyl ester, 2,2 ′, 3,3′-biphenyltetracarboxylic acid dialkyl ester, 2,3,3 ′, 4′-biphenyltetracarboxylic acid dialkyl ester, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dialkyl ester, 2,3,3 ′, 4′-benzophenone tetracarboxylic acid dialkyl ester Bis (3,4-dicarboxyphenyl) ether dialkyl ester, bis (3,4-dicarboxyphenyl) sulfone dialkyl ester, 1,2,5,6-naphthalenetetracarboxylic acid dialkyl ester, 2,3,6, Dialkyl 7-naphthalenetetracar
• the diamine which can be used for reaction with tetracarboxylic dianhydride etc. is not specifically limited. Selection is preferably made to correspond to the desired polyimide precursor structure. Specific examples of diamines that can be selected are as follows.
• aromatic diamines examples include o-phenylene diamine, m-phenylene diamine, p-phenylene diamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 3,5-diaminotoluene, 1,4-diamino- 2-methoxybenzene, 2,5-diamino-p-xylene, 1,3-diamino-4-chlorobenzene, 3,5-diaminobenzoic acid, 1,4-diamino-2,5-dichlorobenzene, 4,4 ′ -Diamino-1,2-diphenylethane, 4,4'-diamino-2,2'-dimethylbibenzyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diamino-3
• aromatic-aliphatic diamines examples include diamines represented by the following formula [DAM].
• Ar represents a benzene ring or a naphthalene ring
• R 1 represents an alkylene group having 1 to 5 carbon atoms
• R 2 represents a hydrogen atom or a methyl group.
• aromatic-aliphatic diamine examples include 3-aminobenzylamine, 4-aminobenzylamine, 3-amino-N-methylbenzylamine, 4-amino-N-methylbenzylamine, 3-aminophenethylamine, 4 -Aminophenethylamine, 3-amino-N-methylphenethylamine, 4-amino-N-methylphenethylamine, 3- (3-aminopropyl) aniline, 4- (3-aminopropyl) aniline, 3- (3-methylaminopropyl) ) Aniline, 4- (3-methylaminopropyl) aniline, 3- (4-aminobutyl) aniline, 4- (4-aminobutyl) aniline, 3- (4-methylaminobutyl) aniline, 4- (4- Methylaminobutyl) aniline, 3- (5-aminopentyl) aniline, 4- (5-aminopen) L) aniline, 3- (5-methylaminopenty
• aliphatic diamines examples include 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino-2,5-dimethylhexane, 1,7- Diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylnonane, 1,12-diaminododecane, Examples thereof include 1,18-diaminooc
• the diamine that can be selected has an alkyl group, a fluorine-containing alkyl group, an aromatic ring, an aliphatic ring, a heterocyclic ring, and a macrocyclic substituent composed of these in the side chain.
• a diamine compound may be used in combination. Specifically, diamines represented by the following formulas [DA-1] to [DA-40] can be exemplified.
• R 6 represents an alkyl group or a fluorine-containing alkyl group having 1 to 22 carbon atoms.
• S 5 represents —COO—, —OCO—, —CONH—, —NHCO—, —CH 2 —, —O—, —CO—, or NH— and R 6 is an alkyl group or a fluorine-containing alkyl group having 1 to 22 carbon atoms.
• S 6 represents —O—, —OCH 2 —, —CH 2 O—, —COOCH 2 —, or CH 2 OCO—
• R 7 Is an alkyl group, alkoxy group, fluorine-containing alkyl group or fluorine-containing alkoxy group having 1 to 22 carbon atoms.
• S 7 represents —COO—, —OCO—, —CONH—, —NHCO—, —COOCH 2 —, —CH 2 OCO—, —CH 2 O—, —OCH 2 —, or CH 2 —
• R 8 is an alkyl group, alkoxy group, fluorine-containing alkyl group, or fluorine-containing alkoxy group having 1 to 22 carbon atoms.
• S 8 represents —COO—, —OCO—, —CONH—, —NHCO—, —COOCH 2 —, —CH 2 OCO—, —CH 2 O—, —OCH 2 —, —CH 2 —, —O—, or NH—
• R 9 is fluorine, cyano, trifluoromethyl, nitro, azo, formyl, acetyl, acetoxy Group or hydroxyl group.
• the following diamines may be used in combination as the selectable diamine.
• n is an integer of 1 to 5).
• [DA-31] and [DA-32] are liquid crystals that use a liquid crystal aligning film formed from a liquid crystal aligning agent that uses the polyimide varnish obtained by the polyimide varnish preparation method of the present invention.
• the voltage holding ratio (VHR) of the display element can be improved.
• it is preferable to use [DA-39] or [DA-40] because it is effective in reducing the accumulated charge of the liquid crystal display element.
• examples of a diamine that can be selected include diaminosiloxanes represented by the following formula [DA-41].
• m is an integer of 1 to 10.
• the diamine is a single polyimide precursor depending on the liquid crystal alignment properties of the liquid crystal alignment film formed from the liquid crystal aligning agent obtained using the polyimide varnish, voltage holding, accumulated charge and the like.
• the diamine is a single polyimide precursor depending on the liquid crystal alignment properties of the liquid crystal alignment film formed from the liquid crystal aligning agent obtained using the polyimide varnish, voltage holding, accumulated charge and the like.
• a known synthesis method can be used to obtain a polyimide precursor by reaction of tetracarboxylic dianhydride and diamine.
• a method in which tetracarboxylic dianhydride and diamine are reacted in an organic solvent is preferable in that the reaction proceeds relatively efficiently in an organic solvent and generation of by-products is small.
• the organic solvent used for the reaction of tetracarboxylic dianhydride and diamine is not particularly limited as long as the produced polyamic acid can be dissolved.
• Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, ⁇ - Butyrolactone, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl carbitol
• tetracarboxylic dianhydride and / or diamine when they are composed of a plurality of types of compounds, they may be reacted in a premixed state, may be individually reacted sequentially, or may be further reacted individually.
• the body may be mixed and reacted to form a high molecular weight body.
• the temperature for reacting the tetracarboxylic dianhydride and the diamine can be arbitrarily selected within the range of ⁇ 20 to 150 ° C., but in the range of ⁇ 5 to 100 ° C. in consideration of the reaction efficiency. Is preferred.
• reaction can be performed by arbitrary density
• the ratio of the number of moles of the tetracarboxylic dianhydride and the diamine is preferably 0.8 to 1.2. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1, the higher the degree of polymerization of the polymer produced. When the degree of polymerization is too small, the strength of the polyimide coating film by the formed polyimide varnish is insufficient, and when the degree of polymerization is too large, workability at the time of forming the polyimide coating film may be deteriorated.
• each of these solutions is mixed to obtain one reaction solution.
• each of the solutions containing the polyimide precursor is diluted with an appropriate solvent such as the above-described solvent, and these solutions are mixed to obtain one reaction solution.
• concentration of the polyimide precursor in the reaction solution is preferably 1 to 12% by mass.
• concentration of the polyimide precursor in the reaction solution is lower than 1% by mass, the interaction between the polyimide precursors becomes weak, and in the resulting polyimide varnish, sufficient printability improvement effect and aggregates at the time of coating film formation The characteristic that it is difficult to form is not fully realized, and the filterability at the time of recovery of the powdered polyimide obtained on the way is deteriorated.
• concentration of the polyimide precursor in a reaction solution is higher than 12 mass%, when collect
• the concentration of the polyimide precursor in the reaction solution is more preferably 3 to 10% by mass, and further preferably 5 to 8% by mass.
• the reaction solution obtained as described above is allowed to elapse for 10 minutes to 12 hours before imidizing each polyimide precursor in the reaction solution, as described later. Is preferred.
• the elapsed time from the reaction solution to imidization is shorter than 10 minutes, the resulting polyimide varnish sufficiently realizes the effect of improving the printability and that it is difficult to form agglomerates during coating formation.
• elapsed time exceeds 12 hours, preparation of a polyimide varnish will take time too much, and the productivity of a polyimide varnish will fall.
• the elapsed time until imidization after obtaining the reaction solution is more preferably 30 minutes to 6 hours, and further preferably 1 to 5 hours.
• reaction solution after obtaining the reaction solution, it is preferable that the reaction solution is stirred until imidization is performed. Moreover, when it is going to shorten the elapsed time until imidation after obtaining the reaction solution, it is preferable to raise the temperature of the reaction solution from room temperature, for example, in a range in which imidization does not proceed.
• Examples of the method for imidizing the polyimide precursor include thermal imidation in which the reaction solution containing the polyimide precursor is heated as it is, catalyst imidization in which a catalyst is added to the reaction solution containing the polyimide precursor, and the like.
• the temperature for thermal imidization in the reaction solution containing the polyimide precursor is 100 to 400 ° C., preferably 120 to 250 ° C., and it is performed while removing water generated by the imidation reaction from the reaction system. preferable.
• the catalytic imidation of the polyimide precursor is performed by adding a basic catalyst and an acid anhydride to the reaction solution containing the polyimide precursor and stirring at -20 to 250 ° C, preferably 0 to 180 ° C. Can do.
• the amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times the amidic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times the amido group. 30 mole times.
• Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like, and among them, pyridine is preferable in that it has an appropriate basicity for proceeding with the reaction.
• Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, acetic anhydride is preferable in that purification after the completion of the reaction is easy.
• the imidization rate by catalytic imidation can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.
• the polyimide is recovered from the obtained polyimide solution.
• the recovered polyimide is, for example, powdered polyimide, and includes two or more types of polyimides having different structures corresponding to two or more types of polyimide precursors having different structures.
• the polyimide solution may be poured into a poor solvent and precipitated.
• the poor solvent used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water.
• the polymer put into a poor solvent and precipitated can be recovered by filtration, and then dried at normal temperature or under reduced pressure at room temperature or by heating.
• impurities in the polymer can be reduced.
• the molecular weight of each polyimide contained in the powdered polyimide is the weight measured by the GPC (Gel Permeation Chromatography) method in consideration of the strength of the film obtained using the polyimide, the workability at the time of forming the coating film, and the uniformity of the coating film.
• the average molecular weight is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000.
• the powdered polyimide containing two or more kinds of recovered polyimide dissolves the polyimide powder in the solvent that can be used for the above-described synthesis reaction of the polyimide precursor. It is dissolved in a solvent that can. And in the preparation method of the polyimide varnish of this invention, it can be set as the state which dissolved 2 or more types of polyimide in the solvent, and can prepare a polyimide varnish.
• the imidation ratio of the polyimide precursor varies depending on the application and purpose, but is preferably adjusted in the range of 40 to 90%, more preferably 45 to 85%.
• two or more types of polyimides corresponding to the type of polyimide precursor are collected, for example, as powders.
• the collected plural kinds of powdery polyimides are mixed to obtain a mixed polyimide powder.
• a mixing means such as stirring for 15 minutes or more with a stirring bar or the like is used.
• the polyimide varnish of the present invention in which two or more kinds of polyimides are dissolved can be prepared by dissolving the obtained mixed polyimide powder in a solvent.
• the tetracarboxylic dianhydride and the diamine that can be selected can be the same as the method for preparing the polyimide varnish described above. And like the preparation method of the polyimide varnish mentioned above, they are made to react and the solution containing a polyimide precursor can be similarly prepared.
• the imidation of the polyimide precursor contained in each solution can be performed in the same manner as the imidization in the reaction solution in the above-described method for preparing a polyimide varnish.
• dissolve the mixed polyimide powder, such as a solvent that can be used for the synthesis reaction of the polyimide precursor in the same manner as the polyimide varnish preparation method described above. It is dissolved in a solvent capable of
• two or more kinds of polyimides are dissolved in a solvent, and a polyimide varnish of another example can be prepared.
• the liquid crystal aligning agent of this invention is manufactured using the polyimide varnish obtained by the preparation method of the polyimide varnish of this invention. That is, the polyimide varnish obtained by the method for preparing the polyimide varnish of the present invention can be used as it is as the liquid crystal aligning agent of the present invention. Moreover, the liquid crystal aligning agent of this invention can also be manufactured by diluting the polyimide varnish obtained by the preparation method of the polyimide varnish of this invention with the suitable solvent mentioned later. Moreover, the liquid crystal aligning agent of this invention can also be manufactured by further adding the additive mentioned later to the polyimide varnish obtained by the preparation method of the polyimide varnish of this invention.
• the liquid crystal aligning agent of this invention is a coating liquid for forming the liquid crystal aligning film used for a liquid crystal display element, and is a solution in which polymers, such as a polyimide contained in the said polyimide varnish, melt
• the liquid crystal aligning agent of this invention is excellent in printability while suppressing generation
• the solid content concentration in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the setting of the thickness of the liquid crystal aligning film formed using the same, but is preferably 0.5 to 10% by mass. It is more preferable to set it as 8 mass%. When the solid content concentration is less than 0.5% by mass, it is difficult to form a uniform and defect-free coating film. When the solid content concentration exceeds 10% by mass, the storage stability of the solution may be deteriorated.
• the term “solid content” as used herein refers to a component obtained by removing the solvent from the liquid crystal aligning agent, and means a polymer such as polyimide as described above and an additive described later.
• the solvent that can be used in the production of the liquid crystal aligning agent of the present invention is not particularly limited as long as it is a solvent that dissolves the resin component. Specific examples are given below.
• solvents that can be used include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethyl-2-pyrrolidone, N -Vinylpyrrolidone, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, ⁇ -butyrolactone, 3-methoxy-N, N-dimethylpropanamide, 3-ethoxy-N, N-dimethylpropanamide, 3- Butoxy-N, N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone
• the liquid crystal aligning agent of this invention can contain an additive.
• additives include solvents and compounds that improve the film thickness uniformity and surface smoothness when a liquid crystal aligning agent is applied, compounds that improve the adhesion between the liquid crystal alignment film to be formed and the substrate, and thermal stability.
• an antioxidant for improving the light resistance and a light stabilizer for improving the light resistance.
• the following are mentioned as a specific example of the solvent (poor solvent) which improves the uniformity of film thickness and surface smoothness.
• These poor solvents may be used alone or in combination.
• the above solvent it is preferably 5 to 80% by mass, more preferably 20 to 60% by mass based on the total amount of the solvent contained in the liquid crystal aligning agent.
• Examples of compounds that improve film thickness uniformity and surface smoothness include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. More specifically, for example, F-top (registered trademark) EF301, EF303, EF352 (manufactured by Tochem Products), MegaFac (registered trademark) F171, F173, R-30 (manufactured by Dainippon Ink and Co., Ltd.), Florard FC430 FC431 (manufactured by Sumitomo 3M), Asahi Guard (registered trademark) AG710, Surflon (registered trademark) S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.) and the like.
• the use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent
• the compound that improves the adhesion between the liquid crystal alignment film and the substrate include the following functional silane-containing compounds and epoxy group-containing compounds.
• the compound that improves the thermal stability include the following phenol compounds.
• Examples of compounds that improve light resistance include the following hindered amine compounds.
• hindered amine compounds For example, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1,2,2,6 , 6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, 1- [2- [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6- Tetramethylpiperidine and the like can be mentioned.
• the liquid crystal aligning agent of the present invention can be applied to a substrate, dried and fired to form a coating film, and the coating film surface is subjected to an alignment treatment such as rubbing treatment or light irradiation to form a liquid crystal alignment film. can do. It is preferable to filter the liquid crystal aligning agent before applying to the substrate.
• the liquid crystal aligning agent of the present invention suppresses the generation of aggregates and is excellent in printability, and the liquid crystal alignment film formed therefrom is excellent in in-plane uniformity of characteristics as a liquid crystal alignment film such as a film thickness. Yes.
• substrate can be used as a board
• a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used in addition to a glass substrate.
• the liquid crystal aligning agent of this invention in manufacture of a liquid crystal display element, it is preferable to form a liquid crystal aligning film using the board
• an opaque substrate such as a silicon wafer can be used as long as only one substrate is used. In this case, a material that reflects light such as aluminum may be used for the electrode. it can.
• the method for applying the liquid crystal aligning agent of the present invention on the substrate is not particularly limited, but industrially, methods such as screen printing, offset printing, flexographic printing, or ink jet method are common. As other coating methods, there are a dipping method, a roll coater method, a slit coater method, a spinner method, a spray method, and the like, and these may be used according to the purpose. Even if the liquid crystal aligning agent of this invention is a case where the above apply
• the drying process after applying the liquid crystal aligning agent is not necessarily required, but if the time from application to baking is not constant for each substrate, or if baking is not performed immediately after application, a drying process is included. Is preferred.
• the drying is not particularly limited as long as the solvent is evaporated to such an extent that the shape of the coating film is not deformed by transporting the substrate or the like. Specific examples include a method of drying on a hot plate at 50 to 150 ° C., preferably 80 to 120 ° C. for 0.5 to 30 minutes, preferably 1 to 5 minutes.
• Calcination of the substrate coated with the liquid crystal aligning agent can be performed at an arbitrary temperature of 100 to 350 ° C. by a heating means such as a hot plate, a thermal circulation oven, or an IR (infrared) oven.
• the firing temperature is preferably 150 to 300 ° C, more preferably 180 to 250 ° C. However, firing is preferably performed at a temperature higher by 10 ° C. or more than the heat treatment temperature required for the manufacturing process of the liquid crystal display element such as sealing agent curing.
• the thickness of the coating film after baking is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may be lowered, so it is preferably 10 to 200 nm, more preferably 50 to 100 nm.
• an existing rubbing apparatus can be used.
• the material of the rubbing cloth at this time include cotton, rayon, and nylon.
• a liquid crystal display element can be produced by a known method after obtaining a substrate with a liquid crystal aligning film by the method described above.
• a pair of substrates having a liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention is prepared.
• the pair of substrates is preferably placed with a spacer of 1 to 30 ⁇ m, more preferably 2 to 10 ⁇ m so that the rubbing direction is an arbitrary angle of 0 to 270 °, and the periphery is sealed with a sealant. Fix it.
• liquid crystal is injected between the substrates and sealed.
• the method for enclosing the liquid crystal is not particularly limited, and examples thereof include a vacuum method in which liquid crystal is injected after reducing the pressure inside the manufactured liquid crystal cell, and a dropping method in which sealing is performed after dropping the liquid crystal.
• the liquid crystal display device thus produced has a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention, has no gap unevenness between substrates that sandwich the liquid crystal, and has excellent display quality, Have high reliability.
• CBDA 1,2,3,4-cyclobutanetetracarboxylic dianhydride
• TDA 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride
• PMDA pyromellitic acid dianhydride
• Anhydride BODA Bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride
• TCA 2,3,5-tricarboxycyclopentylacetic acid dianhydride
• NMP N-methyl-2-pyrrolidone
• GBL ⁇ -butyrolactone
• BCS Butyl cellosolve
• the molecular weights of polyamic acid and polyimide were determined by measuring the polyimide and the like with a GPC (room temperature gel permeation chromatography) apparatus, and calculating the number average molecular weight and the weight average molecular weight as polyethylene glycol and polyethylene oxide equivalent values.
• GPC room temperature gel permeation chromatography
• GPC device manufactured by Shodex (GPC-101) Column: manufactured by Shodex (series of KD803 and KD805) Column temperature: 50 ° C Eluent: N, N-dimethylformamide (as additives, lithium bromide-hydrate (LiBr ⁇ H 2 O) is 30 mmol / L (liter), phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 Mmol / L, tetrahydrofuran (THF) 10 ml / L) Flow rate: 1.0 ml / min Standard sample for preparing calibration curve: TSK standard polyethylene oxide (molecular weight: about 900,000, 150,000, 100,000, and 30000) manufactured by Tosoh Corporation, and polyethylene glycol (molecular weight: about 12,000, 4000, and 1000).
• a polyamic acid is prepared by reacting TDA (14.87 g, 0.049 mol) as a tetracarboxylic dianhydride component and 9.91 g (0.05 mol) as a diamine component in NMP (74.6 g) at 50 ° C. for 20 hours.
• a solution of (PAA-7) having a concentration of 20 wt% was obtained.
• the viscosity of this polyamic acid solution at a temperature of 25 ° C. was 483 mPa ⁇ s.
• Example 1 278.9 g of NMP was added to 276.9 g of the polyamic acid solution (PAA-1) obtained in the same manner as in Synthesis Example 1 and diluted to prepare a polyamic acid solution (PAA-1-2) having a concentration of 8% by mass. did.
• PAA-1-2 polyamic acid solution
• PAA-2-2 polyamic acid solution
• Example 2 32.0 g of NMP was added to 22.0 g of the polyamic acid solution (PAA-3) obtained in the same manner as in Synthesis Example 3 and diluted to prepare a polyamic acid solution (PAA-3-2) having a concentration of 8% by mass. did.
• PAA-3-2 polyamic acid solution obtained in the same manner as in Example 1
• 505.0 g of acetic anhydride was added to 275.0 g of this mixed solution.
• .13 g and pyridine 23.31 g were added and reacted at 40 ° C. for 3 hours to imidize.
• the obtained polyimide solution was cooled to about room temperature and then poured into 1186 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-2).
• SPI-2 polyimide
• the number average molecular weight of this polyimide was 9967, and the weight average molecular weight was 24637.
• the imidation ratio was 94%.
• Example 3 22.5 g of NMP was added to 15.0 g of the polyamic acid solution (PAA-4) obtained in the same manner as in Synthesis Example 4 and diluted to prepare a polyamic acid solution (PAA-4-2) having a concentration of 8% by mass. did.
• PAA-4-2 polyamic acid solution obtained in the same manner as in Synthesis Example 4
• PAA-4-2 polyamic acid solution obtained in the same manner as in Example 1
• 87.5 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1 was mixed with 37.5 g of PAA-4-2, and 125.0 g of this mixed solution was mixed with 13 acetic anhydride. .26 g and 10.28 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize.
• the obtained polyimide solution was cooled to about room temperature, and then poured into 509 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-3).
• the number average molecular weight of this polyimide was 5185, and the weight average molecular weight was 20781. Moreover, the imidation ratio was 50%.
• SPI-3 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring.
• Example 4 22.5 g of NMP was added to 15.0 g of the polyamic acid solution (PAA-5) obtained in the same manner as in Synthesis Example 5 and diluted to prepare a polyamic acid solution (PAA-5-2) having a concentration of 8% by mass. did.
• PAA-5-2 polyamic acid solution obtained in the same manner as in Synthesis Example 5
• PAA-5-2 polyamic acid solution having a concentration of 8% by mass.
• 87.5 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1 was mixed with 37.5 g of PAA-5-2, and 125.0 g of this mixed solution was mixed with acetic anhydride 13 .31 g and 10.31 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize.
• the obtained polyimide solution was cooled to about room temperature, and then poured into 513 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-4).
• the number average molecular weight of this polyimide was 9996, and the weight average molecular weight was 26884. Moreover, the imidation ratio was 65%.
• SPI-4 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring.
• Example 5 To 350.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1, 21.08 g of acetic anhydride and 8.99 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1330 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-5). The number average molecular weight of this polyimide was 10920, and the weight average molecular weight was 31108. The imidation ratio was 80%.
• Example 6 To 110.0 g of the polyamic acid solution (PAA-1-2) obtained in the same manner as in Example 1, 52.68 g of acetic anhydride and 24.50 g of pyridine were added and reacted at 40 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 1185 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-7). The number average molecular weight of this polyimide was 9781, and the weight average molecular weight was 24985. Moreover, the imidation ratio was 95%.
• SPI-7 ocher powder of polyimide
• polyimide (SPI-5) obtained in the same manner as in Example 5 and 2.1 g of SPI-9 were mixed, 58.3 g of GBL was added, and the mixture was stirred at 50 ° C. for 20 hours.
• the polyimide was completely dissolved at the end of stirring.
• 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours.
• the solid content (SPI-5 + SPI-9) was 5.0% by mass, and GBL was 47.5% by mass. %, NMP was 19.0 mass%, and BCS was 28.5 mass%.
• This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is.
• the aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.
• Example 8 To 450.0 g of the polyamic acid solution (PAA-5-2) obtained in the same manner as in Example 4, 14.45 g of acetic anhydride and 11.20 g of pyridine were added and reacted at 50 ° C. for 2 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 559 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-10). The number average molecular weight of this polyimide was 11133, and the weight average molecular weight was 23773. Moreover, the imidation ratio was 65%.
• polyimide (SPI-5) obtained in the same manner as in Example 5 and 2.1 g of SPI-10 were mixed, 58.3 g of GBL was added, and the mixture was stirred at 50 ° C. for 20 hours.
• the polyimide was completely dissolved at the end of stirring.
• 8.2 g of GBL, 26.6 g of NMP and 39.9 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours.
• the solid content (SPI-5 + SPI-10) was 5.0% by mass, and GBL was 47.5% by mass. %, NMP was 19.0 mass%, and BCS was 28.5 mass%.
• This polyimide varnish can be used as a liquid crystal aligning agent for forming a liquid crystal alignment film as it is.
• the aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.
• the solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-11).
• the number average molecular weight of this polyimide was 10739, and the weight average molecular weight was 23,093.
• the imidation ratio was 87%.
• the solid content (SPI-11) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33.3%.
• a polyimide varnish having 3 wt% and 14.3 wt% BCS was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is.
• the aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.
• Example 11 100.0 g of the polyamic acid solution (PAA-3-2) obtained in the same manner as in Example 2 and 100.0 g of the polyamic acid solution (PAA-5-2) obtained in the same manner as in Example 4 were mixed. Then, 43.14 g of acetic anhydride and 20.06 g of pyridine were added to 200.0 g of this mixed solution, and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 834 g of methanol to recover the precipitated solid. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-13).
• This polyimide had a number average molecular weight of 9,986 and a weight average molecular weight of 2,016. Moreover, the imidation ratio was 70%. 80.7 g of GBL was added to 11.0 g of the obtained polyimide (SPI-13), and the mixture was stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours. The solid content (SPI-13) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33.
• Example 12 5.5 g of polyimide (SPI-8) obtained in the same manner as in Example 6 and 5.5 g of polyimide (SPI-10) obtained in the same manner as in Example 8 were mixed, and 80.7 g of GBL was added. Stir at 20 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours.
• the solid content (SPI-8 + SPI-10) was 5.0 wt%, GBL was 47.4 wt%, and NMP was 33 A polyimide varnish having a content of 0.3 wt% and a BCS of 14.3 wt% was obtained.
• This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is.
• the aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.
• the solid was washed twice with methanol and dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-14).
• the number average molecular weight of this polyimide was 10917, and the weight average molecular weight was 22582. Moreover, the imidation ratio was 85%.
• 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours.
• Example 14 To 100.0 g of the polyamic acid solution (PAA-7-2) obtained in the same manner as in Example 13, 16.38 g of acetic anhydride and 7.62 g of pyridine were added and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 345 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-15). The number average molecular weight of this polyimide was 10003, and the weight average molecular weight was 21093. Further, the imidization ratio was 83%.
• Example 15 100.0 g of the polyamic acid solution (PAA-4-2) obtained in the same manner as in Example 3 and 100.0 g of the polyamic acid solution (PAA-7-2) obtained in the same manner as in Example 13 were mixed. Then, 22.46 g of acetic anhydride and 17.40 g of pyridine were added to 200.0 g of this mixed solution, and reacted at 50 ° C. for 3 hours to imidize. The obtained polyimide solution was cooled to about room temperature and then poured into 840 g of methanol, and the precipitated solid was recovered. The solid was washed twice with methanol and then dried under reduced pressure at 100 ° C. to obtain an ocher powder of polyimide (SPI-16).
• SPI-16 ocher powder of polyimide
• the number average molecular weight of this polyimide was 9765, and the weight average molecular weight was 21724. Moreover, the imidation ratio was 61%.
• SPI-16 polyimide
• 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.7 g of GBL, 73.2 g of NMP and 31.4 g of BCS were added to this solution and stirred at 50 ° C. for 20 hours.
• the solid content (SPI-16) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33.
• a polyimide varnish having 3 wt% and 14.3 wt% BCS was obtained. This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is.
• the aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.
• the solid content (SPI-9 + SPI-15) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33 A polyimide varnish having a content of 0.3 wt% and a BCS of 14.3 wt% was obtained.
• This polyimide varnish becomes a liquid crystal alignment agent for forming a liquid crystal alignment film as it is.
• the aggregation start time of the obtained polyimide varnish was evaluated according to the evaluation method described above. The evaluation results are shown in Table 1.
• polyimide (SPI-6) obtained in the same manner as in Example 5, 80.7 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours.
• the solid content (SPI-6) was 5.0% by mass
• GBL was 47.5% by mass
• a polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
• the polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours.
• the solid content (SPI-8) was 5.0% by mass
• GBL was 47.4% by mass
• a polyimide solution having NMP of 33.3% by mass and BCS of 14.3% by mass was obtained.
• 140 g of the polyimide solution obtained above (SPI-7 concentration 5.0 mass%) and 60 g polyimide solution (SPI-8 concentration 5.0 mass%) were mixed and stirred at room temperature for 2 hours.
• polyimide (SPI-5) obtained in the same manner as in Example 5, 58.3 g of GBL was added and stirred at 50 ° C. for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-5) was 5.0 mass%, GBL was 47.5 mass%, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
• GBL58.3g was added to 7.0g of polyimides (SPI-5) obtained by carrying out similarly to Example 5, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Furthermore, GBL8.2g, NMP26.6g, and BCS39.9g were added to this solution, and it stirred at 50 degreeC for 20 hours, solid content (SPI-5) was 5.0 mass%, GBL was 47.5 mass%, A polyimide solution having NMP of 19.0% by mass and BCS of 28.5% by mass was obtained.
• GBL80.7g was added to 11.0g of polyimides (SPI-12) obtained by carrying out similarly to Example 10, and it stirred at 50 degreeC for 20 hours. The polyimide was completely dissolved at the end of stirring. Further, 23.8 g of GBL, 41.8 g of NMP and 62.7 g of BCS were added to this solution, and the mixture was stirred at 50 ° C. for 20 hours. The solid content (SPI-12) was 5.0 wt%, GBL was 47.4 wt% and NMP was 33. A polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
• GBL80.7g was added to 11.0g of polyimides (SPI-10) obtained by carrying out similarly to Example 8, and it stirred at 50 degreeC for 20 hours.
• the polyimide was completely dissolved at the end of stirring.
• 23.8 g of GBL, 41.8 g of NMP, and 62.7 g of BCS were added to this solution, followed by stirring at 50 ° C. for 20 hours.
• the solid content (SPI-10) was 5.0 wt%
• GBL was 47.4 wt%
• NMP was 33.
• a polyimide solution with 3 wt% and BCS 14.3 wt% was obtained.
• Example 5 to 8, 10, 12, 14 and 16 two kinds of powdered polyimides were separately prepared, mixed, and then dissolved in a solvent, and two kinds of polyimide were dissolved in the solvent. A polyimide solution is obtained and a polyimide varnish is prepared.
• the varnish preparation methods of Examples 5 to 8, 10, 12, 14, and 16 are described as “II” in Table 1.
• Comparative Examples 1 to 8 two kinds of powdered polyimides were prepared separately, and each was dissolved in a solvent to obtain two kinds of polyimide solutions, and then each polyimide solution was mixed to obtain two kinds of polyimides.
• a polyimide varnish is prepared by obtaining a polyimide solution in which is dissolved in a solvent.
• the varnish preparation methods of Comparative Examples 1 to 8 are described as “III” in Table 1.
• the polyimide varnishes of Examples 1 to 4, 9, 11, 13 and 15 are comparative examples in which the polyamic acid solutions (PAA-1 to PAA-7) used are the same and the varnish preparation methods are different. Compared with 1 to 8, it was found that the aggregation start time was longer and the generation of aggregates during the formation of the coating film hardly occurred. Similarly, in the polyimide varnishes of Examples 5 to 8, 10, 12, 14 and 16, the polyamic acid solutions (PAA-1 to PAA-7) used were the same, and Comparative Examples 1 to 8 having different varnish preparation methods were used. In comparison, it was found that the aggregation start time was long and the generation of aggregates during the formation of the coating film hardly occurred.
• the polyimide varnishes of Examples 1 to 16 can provide a liquid crystal aligning agent in which aggregates are hardly generated when a coating film is formed.
• the liquid crystal aligning agents using the polyimide varnishes of Examples 1 to 4 are particularly suitable for suppressing the generation of aggregates during the formation of the coating film.
• the polyimide varnish obtained by the method for preparing a polyimide varnish of the present invention is suitably used as a liquid crystal aligning agent having characteristics that it is excellent in printability and is difficult to form an aggregate during coating film formation.
• a liquid crystal display element having a liquid crystal alignment film formed using the liquid crystal aligning agent of the present invention has a high display quality with excellent display uniformity, and displays a large liquid crystal TV or a high-definition image. It can use suitably as a display element for portable information terminals, such as a smart phone.

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