Classifications

• • 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
  • C08G73/14—Polyamide-imides
• • 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
  • C08G73/1039—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors comprising halogen-containing substituents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets

Definitions

• the present invention relates to a polyamide-imide copolymer that can be suitably used for a cover window of a foldable display element such as a foldable device.
• Foldable devices have recently been attracting attention in order to further enhance the portability of mobile information terminals such as smartphones and tablets.
• a member such as a cover window used for a flexible display constituting such a foldable device, it is necessary to have flexibility in addition to transparency.
• a member having extremely high flexibility that can realize a bending of 180 ° with a small bending radius of about 2.5 mm.
• a fluorine-substituted polyimide film has been attracting attention as a film for a flexible display having heat resistance, transparency, mechanical strength, surface hardness, and bending resistance.
• the polyamideimide copolymer as proposed in Patent Document 1 and the like is 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride as a tetracarboxylic acid dianhydride component that contributes to solubility and transparency.
• a fluorine-substituted acid anhydride such as a substance (6FDA) is used, and 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (sBPDA) or the like is used as a tetracarboxylic acid dianhydride component that contributes to bending resistance. It has an imide structural unit using the acid anhydride of No. 1 and an amide structural unit using terephthalic acid chloride (TPC) which contributes to mechanical strength as a dicarboxylic acid component.
• TPC terephthalic acid chloride
• the toughness such as bending resistance of the copolymer is improved by using an acid anhydride having an intermolecular interaction such as sBPDA
• the YI value (yellowish) of the copolymer is due to ⁇ -electron conjugation.
• an object of the present invention is to provide a polyamide-imide copolymer having excellent toughness such as bending resistance, excellent transparency, and good wettability and adhesion when made into a film.
• the present inventors have focused on the imide structural unit of the polyamide-imide copolymer and investigated various tetracarboxylic acid dianhydrides. By combining two specific tetracarboxylic acid dianhydrides, the above-mentioned We obtained the finding that the problem can be solved. The present invention has been completed based on such findings.
• the gist of the present invention is as follows.
• the imide structural unit is the imide structural unit I-1 represented by the following formula (1): and, At least one imide structural unit selected from the group consisting of the following formulas (2) to (5): I-2: (In the formulas (1) to (5), X 1 to X 5 each independently represent a divalent organic group derived from a diamine.)
• Including The amide structural unit is represented by the following formula (6): amide structural unit A: (In the formula, X 6 represents a divalent organic group derived from a diamine, and Y represents a divalent organic group derived from a dicarboxylic acid or a dicarboxylic acid derivative.)
• a polyamide-imide copolymer comprising.
• X 1 to X 6 are the following equations (7): (In the formula, * is a binding group.)
• Y is the following equations (8) to (10): (In the formula, * is a binding group.)
• [4] The polyamide-imide copolymer according to any one of [1] to [3], wherein the imide structural unit I-2 is represented by the above formula (2).
• [5] The polyamide-imide copolymer according to any one of [1] to [4], wherein the imide structural unit and the amide structural unit are contained in a molar ratio of 2: 8 to 8: 2.
• [6] A film containing the polyamide-imide copolymer according to any one of [1] to [5].
• [7] The film according to [6], wherein the contact angle of water on the surface of a film having a thickness of 50 ⁇ m measured in accordance with JIS R3257: 1999 is 55 degrees or less.
• the film according to [6] or [7] which is used as a cover window of a foldable device.
• the toughness such as bending resistance is excellent, the transparency is also excellent, and the film is wet when formed. It is possible to realize a polyamide-imide copolymer having good properties and adhesion.
• the polyamide imide copolymer according to the present invention is a copolymer having an imide structure and an amide structure, and the imide structural unit is the imide structural unit I-1 represented by the following formula (1) and the following formula (2). It is provided with at least one imide structural unit I-2 selected from the group consisting of the group represented by (5), and has the amide structural unit A represented by the following formula (6) as the amide structural unit. be.
• the imide structural unit constituting the polyamide-imide copolymer As the imide structural unit constituting the polyamide-imide copolymer, the structural unit I-1 represented by the above formula (1) and one or more of the structural units (2) to (5) are used. By combining with I-2, the transparency of the polyamide-imide copolymer, the wettability when formed into a film, and the adhesion to other members can be improved at the same time.
• a fluorine-substituted tetracarboxylic acid dianhydride such as 6FDA is used as the tetracarboxylic acid dianhydride component of the imide structural unit as in the conventional polyamide-imide copolymer, the transparency of the obtained polyamide-imide copolymer is obtained.
• the structural unit represented by the above formula (2) is preferable. That is, in the present invention, a combination of aODPA and sODPA is preferable as the tetracarboxylic dianhydride constituting the imide structural unit.
• the ratio of the polyamide-imide copolymer to I-1 and I-2 constituting the imide structural unit is preferably in the range of 2: 1 to 1: 2 in terms of molar ratio, and is preferably in the range of 3: 2 to 2: 3. It is more preferably in the range.
• the polyamide-imide copolymer of the present invention may contain components other than those described above as the imide structural unit as long as the effects of the present invention are not impaired.
• the tetracarboxylic acid component constituting the imide structural unit include various tetracarboxylic acids or tetracarboxylic acid derivatives, and examples of the tetracarboxylic acid derivative include tetracarboxylic acid anhydrides, preferably dianhydrides and acid chlorides. Be done.
• tetracarboxylic acid compound examples include aromatic tetracarboxylic acid and its anhydride, preferably an aromatic tetracarboxylic acid compound such as its dianhydride; an aliphatic tetracarboxylic acid compound and its anhydride, preferably its dianhydride.
• aromatic tetracarboxylic acid compound such as its dianhydride
• aliphatic tetracarboxylic acid compound and its anhydride preferably its dianhydride.
• examples thereof include aliphatic tetracarboxylic acid compounds such as. These tetracarboxylic acid compounds can be used alone or in combination of two or more.
• aromatic tetracarboxylic acid dianhydride examples include a non-condensed polycyclic aromatic tetracarboxylic acid dianhydride, a monocyclic aromatic tetracarboxylic acid dianhydride, and a condensed polycyclic aromatic tetra. Examples include carboxylic acid dianhydride. Examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (sBPDA), 4,4'-(4,4'-isopropi).
• sBPDA 4,4'-biphenyltetracarboxylic acid dianhydride
• Examples of the monocyclic aromatic tetracarboxylic acid dianhydride include 1,2,4,5-benzenetetracarboxylic acid dianhydride, and the condensed polycyclic aromatic tetracarboxylic acid dianhydride. Examples thereof include 2,3,6,7-naphthalenetetracarboxylic acid dianhydride.
• Examples of the aliphatic tetracarboxylic dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydride.
• the cyclic aliphatic tetracarboxylic acid dianhydride is a tetracarboxylic acid dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride.
• Cycloalkanthtetracarboxylic acid dianhydrides such as (HPMDA), 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic acid dianhydrides, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydrides.
• acyclic aliphatic tetracarboxylic acid dianhydride examples include 1,2,3,4-butanetetracarboxylic acid dianhydride, 1,2,3,4-pentanetetracarboxylic acid dianhydride and the like. These can be used alone or in combination of two or more. Further, a cyclic aliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used in combination.
• the imide structural unit may contain the above-mentioned aqueous adduct of tetracarboxylic dianhydride or the structural unit derived from the tricarboxylic acid compound in addition to the above-mentioned structural unit.
• the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, acid chloride compounds related thereto, acid anhydrides, and the like, and two or more of them may be used in combination.
• Specific examples include anhydrate of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalentricarboxylic acid-2,3-anhydride; a single bond of phthalic anhydride and benzoic acid, -O-. , -CH 2- , -C (CH 3 ) 2- , -SO 2- or a compound linked with a phenylene group can be mentioned.
• the polyamide-imide copolymer according to the present invention contains an amide structural unit A represented by the following formula (6).
• a copolymer having an imide structure having rigid properties and an amide structure having flexible properties there is a trade-off relationship between excellent flexibility and high elasticity without sacrificing transparency and wettability.
• a certain mechanical property can be realized at a high level.
• X 6 represents a divalent organic group derived from a diamine
• Y represents a divalent organic group derived from a dicarboxylic acid or a dicarboxylic acid derivative.
• the polyamide imide copolymer containing the above-mentioned amide structural unit A can be obtained by reacting a diamine compound, a tetracarboxylic acid compound and a dicarboxylic acid compound which are monomer components, and specifically, the diamine compound and the tetracarboxylic acid compound.
• a diamine compound a tetracarboxylic acid compound and a dicarboxylic acid compound which are monomer components, and specifically, the diamine compound and the tetracarboxylic acid compound.
• To synthesize a polymer having an imide precursor structure and then reacting the polymer with a dicarboxylic acid compound to synthesize a copolymer having an imide precursor structure and an amide structure, and then the co-weight. It is obtained by subjecting the imide precursor structure in the coalescence to a ring-closing reaction (imidization).
• the polyamide imide copolymer consists of a structural unit in which residues obtained by reacting a diamine compound and a tetracarboxylic acid compound are bonded via an imide structure, and residues reacted by a dicarboxylic acid compound via an amide structure. Has a structure.
• Y is a divalent organic group derived from a dicarboxylic acid or a dicarboxylic acid derivative.
• the dicarboxylic acid derivative include an acid chloride of the dicarboxylic acid. Examples include an ester form.
• Dicarboxylic acids can be used alone or in combination of two or more.
• dicarboxylic acid examples include, for example, 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4,4'-oxybis benzoic acid, terephthalic acid, and isophthalic acid.
• 2,6-naphthalenedicarboxylic acid 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, two cyclohexanecarboxylic acids or two An alicyclic dicarboxylic acid or fragrance such as a compound in which the benzoic acid is single-bonded, -CH 2- , -C (CH 3 ) 2- , -C (CF 3 ) 2- , -SO 2- or a phenylene group.
• Group dicarboxylic acids and their derivatives eg, acid chlorides, acid anhydrides
• aliphatic dicarboxylic acids such as dicarboxylic acid compounds of chain hydrocarbons having 8 or less carbon atoms and their derivatives (eg, acid chlorides, esters) and the like. Can be mentioned.
• These dicarboxylic acid compounds can be used alone or in combination of two or more.
• terephthalic acid isophthalic acid, 4,4'-biphenyldicarboxylic acid, or 4,4'-oxybis benzoic acid or a derivative thereof, particularly, from the viewpoint of improving the elongation at break point and the elasticity as a film.
• TPC terephthalic acid chloride
• IPC isophthalic acid chloride
• BPC 4,4'-biphenyldicarbonyl chloride
• OBBC 4,4'-oxybis (benzoyl chloride)
• Y is a divalent organic group derived from TPC, the amide structural unit A-1 represented by the following formula (11), and Y is a divalent organic group derived from IPC, the following formula (12). It is preferable to have the amide structural unit A-2 represented by the above, or the amide structural unit A-3 represented by the following formula (13) in which Y is a divalent organic group derived from BPC, and in particular, the amide structure. It is preferable to have the unit A-1. (In the formula, X 6 represents a divalent organic group derived from diamine.)
• the above-mentioned amide structural unit A-1 and other amide structural units may be used in combination, and examples of the other amide structural unit include those derived from the above-mentioned various dicarboxylic acids or dicarboxylic acid derivatives.
• the amide structural unit A-2 or A-3 is preferred.
• the composition ratio thereof is from the viewpoint of the balance between optical properties such as transparency and mechanical properties such as mechanical strength. Is preferably in the range of 10: 1 to 5: 1.
• the composition ratio (molar ratio) of the imide structure to the amide structure in the polyamide-imide copolymer of the present invention is preferably 0.5 to 4: 3 to 6.5, more preferably 1.5 to 3.5 :.
• the ratio is 3.5 to 5.5, particularly preferably 3: 4, and the composition ratio of the imide structure and the amide structure is the above-mentioned composition ratio, so that excellent flexibility and high elasticity can be achieved in a well-balanced manner.
• the diamine component (that is, the divalent organic group represented by X 1 to X 6 ) constituting the above-mentioned imide structural unit and amide structural unit is not particularly limited, and conventionally known polyimide or polyamide-imide is not particularly limited.
• the diamine component used in the above can be used, and examples thereof include aliphatic diamines, aromatic diamines and mixtures thereof.
• aromatic diamine represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or another substituent may be contained in a part of the structure.
• the aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring. Among these, a benzene ring is preferable.
• the "aliphatic diamine” represents a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be contained as a part of the structure thereof. Diamine compounds can be used alone or in combination of two or more.
• aliphatic diamine examples include acyclic aliphatic diamines such as hexamethylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, norbornanediamine, 4,4'.
• -Cycholic aliphatic diamines such as diaminodicyclohexylmethane can be mentioned. These can be used alone or in combination of two or more.
• aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylene diamine, p-xylylene diamine, 1,5-diaminonaphthalene, and 2,6-diamino.
• Aromatic diamines having one aromatic ring such as naphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3 '-Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-Aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) Pheny
• a substituent selected from a fluoro group, a trifluoromethyl group, or a trifluoromethoxy group from the viewpoint of easily improving colorless transparency.
• TFMB 2,2'-bis (trifluoromethyl) benzidine
• the above-mentioned TFMB may be used alone, or one or more of the above-mentioned various diamine compounds may be used in combination with TFMB.
• the composition ratio is in the range of 10: 1 to 5: 1 from the viewpoint of the balance between optical properties such as transparency and mechanical properties such as mechanical strength. Is preferable.
• the composition ratio of the monomer components may be 7: 0.5 to 4: 3 to 6.5 as a molar ratio. It is more preferably 7: 1.5 to 3.5: 3.5 to 5.5, and particularly preferably 7: 3: 4.
• the ring-closing reaction (imidization) of the imide precursor obtained by reacting the above-mentioned diamine compound and the tetracarboxylic acid compound, or the imide precursor by reacting the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is coexisting with water.
• a boiling co-boiling solvent eg, toluene, xylene, etc.
• chemical imidization using a condensing agent and a reaction accelerator can be used, but colorless transparency is maintained. Therefore, chemical imidization is preferable.
• Reaction accelerators used for chemical imidization include triethylamine, diisopropylethylamine, N-methylpiperidin, pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 3-ethylpyridine, 3,5-dimethylpyridine, and the like. Examples thereof include 3,5-diethylpyridine, isoquinoline, imidazole, 1-methylimidazole, 2-methylimidazole and 1,2-dimethylimidazole. These reaction accelerators may be one kind or a combination of two or more kinds.
• Condensing agents used for chemical imidization include acid anhydrides such as acetic acid anhydride, propionic acid anhydride, and trifluoroacetic acid anhydride, phosphorous acid ester, triethyl phosphite, triethyl phosphite, tributyl phosphite, and phosphorous acid. Examples thereof include phosphite esters such as dimethyl, diethyl phosphite, and triphenyl phosphite. These condensing agents may be one kind or a combination of two or more kinds.
• the imidization rate is preferably 90% or more, more preferably 93% or more, still more preferably 96% or more. From the viewpoint of easily increasing the optical homogeneity such as transparency, a high imidization ratio is preferable. Further, the upper limit of the imidization rate is 100% or less.
• the imidization ratio indicates the ratio of the molar amount of imide bond in the imide structural unit to the value of twice the molar amount of the structural unit derived from tetracarboxylic acid dianhydride in the imide structural unit.
• the imidization rate can be obtained by an IR method, an NMR method, or the like.
• the organic solvent used for the synthesis of the polyamide-imide copolymer is not particularly limited as long as it is an organic solvent that is inert to the reaction.
• organic solvent for example, N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, m-cresol, ⁇ -butyrolactone, cyclopentanone, cyclohexanone, tetrahydrofuran. And so on.
• DMAc N, N-dimethylacetamide
• N-methyl-2-pyrrolidone 1,3-dimethyl-2-imidazolidinone
• dimethyl sulfoxide m-cresol
• ⁇ -butyrolactone ⁇ -butyrolactone
• cyclopentanone cyclohexanone
• tetrahydrofuran tetrahydrofuran.
• the reaction conditions for the synthesis can be 1 to 27 hours or less at 10 to 50 ° C., and it is preferable to synthesize in a nitrogen atmosphere from the viewpoint of maintaining colorless transparency.
• the polyamide-imide copolymer can be isolated (separated and purified) by a conventional method, for example, a separation means such as filtration, concentration, extraction, crystallization, recrystallization, or column chromatography, or a separation means combining these.
• a separation means such as filtration, concentration, extraction, crystallization, recrystallization, or column chromatography, or a separation means combining these.
• a reaction solution containing a transparent polyamide-imide resin can be isolated by adding a large amount of alcohol such as methanol to precipitate the resin, and concentrating, filtering, drying and the like.
• the weight average molecular weight (Mw) of the resin having an imide structure obtained as described above is preferably in the range of 50,000 to 1,000,000 from the viewpoint of improving the elastic modulus and the elongation at break point. , 80,000 to 800,000, more preferably 110,000 to 650,000.
• the weight average molecular weight (Mw) is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.
• the polyamide-imide copolymer of the present invention is dissolved in an appropriate solvent to form a resin composition (resin varnish), and the resin composition is applied onto a support to form a coating film, and then the coating film is dried.
• a film can be obtained by removing the solvent and peeling it from the support.
• the solvent can be used without particular limitation as long as it can dissolve polyamideimide, but from the viewpoint of the coatability of the resin varnish and the transparency of the obtained film, an ester group, an ether group, a ketone group, etc. can be used.
• a solvent containing at least one selected from the group consisting of a hydroxyl group, a sulfone group and a sulfinyl group is preferable.
• Examples of the solvent having an ester group include ester solvents such as methyl acetate, ethyl acetate, butyl acetate and dimethyl carbonate.
• Examples of the solvent having a cyclic ester group include lactone-based solvents such as ⁇ -butyrolactone (GBL), ⁇ -valerolactone, ⁇ -caprolactone, ⁇ -crotonolactone, ⁇ -hexanolactone, and ⁇ -methyl- ⁇ -butyrolactone. , ⁇ -Valerolactone, ⁇ -acetyl- ⁇ -butyrolactone, ⁇ -hexanolactone and the like.
• Examples of the solvent having an ether group include tetrahydrofuran, dioxane, dibutyl ether and the like.
• Examples of the solvent having a ketone group include a ketone solvent, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like.
• Examples of the solvent having a hydroxyl group include phenolic solvents such as m-cresol.
• Examples of the solvent having a sulfone group include methyl sulfone, ethyl phenyl sulfone, diethyl sulfone, diphenyl sulfone, sulfolane, bisphenol S, sorapson, dapson, bisphenol A polysulfone, sulfolane and the like.
• Examples of the solvent having a sulfinyl group include sulfoxide-based solvents such as N, N-dimethyl sulfoxide (DMSO).
• amide solvents such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and the like may be used. Can be done.
• NMP N-methyl-2-pyrrolidone
• DMF N-dimethylformamide
• DMAc N-dimethylacetamide
• the resin composition for forming a film may contain any component other than the polyamideimide copolymer, for example, a leveling agent for improving the coatability of a varnish when producing a film.
• a leveling agent for improving the coatability of a varnish when producing a film.
• the content of the polyamide-imide copolymer in the resin composition is preferably in the range of 65 to 100% by mass, more preferably in the range of 80 to 100% by mass, based on the total amount of solids excluding the solvent. , 90-100% by mass, more preferably.
• conventionally known means can be applied, for example, a dip coating method, a flow coating method, a roll coating method, a bar coater method, and a blade.
• a coater method a screen printing method, a curtain coating method, and a spray coating method.
• the drying conditions of the coating film are not particularly limited as long as the temperature at which the solvent volatilizes, but from the viewpoint of obtaining a film having excellent transparency, it is preferably about 10 to 60 minutes at 60 to 250 ° C.
• the film thickness of the present invention is preferably 5 ⁇ m or more and 100 ⁇ m or less, and more preferably 10 ⁇ m or more and 50 ⁇ m or less. By setting the film thickness within the above range, a film having excellent flexibility can be obtained, so that the film can be suitably used as a cover window of a foldable display or a flexible display.
• the film thickness can be adjusted by the amount of the resin composition applied.
• the film of the present invention is formed from a polyamide-imide copolymer containing two specific imide structural units as described above, it has excellent toughness such as bending resistance, excellent transparency, and a surface surface. It also has good wettability and adhesion to other materials.
• the YI value can be 2.0 or less.
• the film of the present invention is also excellent in wettability and adhesion.
• a film formed on a glass substrate so as to have a film thickness of 50 ⁇ m and having an arithmetic average surface roughness Ra of the surface of 50 nm or less is used.
• the contact angle of water is 55 degrees or less.
• the contact angle of water means the contact angle of water measured in accordance with JIS R3257: 1999, and the arithmetic mean surface roughness Ra was measured by a measuring device in accordance with JIS B0601-1994. Means a value.
• Display members using the film of the present invention include, for example, thin and bendable foldable organic EL displays, mobile terminals such as smartphones and wristwatch-type terminals, display devices inside automobiles, and flexible wristwatches. Examples include the use of members such as panels.
• members for image display devices such as liquid crystal display devices and organic EL display devices, touch panel members, flexible printed substrates, solar cell panel members such as surface protective films and substrate materials, optical waveguide members, and other semiconductor-related members. It can also be applied to such as. Above all, it is suitably used for members such as cover windows and TFT substrates constituting a foldable type organic EL display.
• the cover window of the display using the film of the present invention for example, the film is arranged and used so as to be located on the surface of various displays.
• the method of arranging on the surface is not particularly limited, and examples thereof include a method via an adhesive layer and the like.
• the material of the adhesive layer a conventionally known adhesive material that can be used for adhering the surface material for a display can be used.
• the cover window of the display using the film of the present invention may be provided with a protective layer such as a hard coat layer and a fingerprint adhesion prevention layer on the film surface.
• the TFT substrate for an organic EL display using the film of the present invention can be obtained, for example, by forming an amorphous silicon TFT (thin film transistor) on the film of the present invention.
• the TFT includes a gate metal layer, a silicon nitride gate dielectric layer, and an ITI pixel electrode. Further, a structure required for an organic EL display can be formed on this by a known method, and the method for forming a circuit or the like is not particularly limited.
• Example 1 ⁇ Preparation of polyamide-imide> A 100 mL reactor was filled with 60.9 g of DMAc and 4.849 g (15.14 mmol) of TFMB was added. Next, 1.007 g (3.245 mmol) of aODPA and 1.4875 g (3.245 mmol) of BPAF are added to this solution of TFMB, and the mixture is stirred and reacted at 30 ° C. for 2 hours to contain a polymer having an imide precursor structure. A solution was obtained. Then, 1.757 g (8.653 mmol) of TPC was added to this solution, and the mixture was stirred and reacted for 1.5 hours while keeping the liquid temperature at 30 ° C.
• Example 2 A polyamide-imide solution was obtained in the same manner as in Example 1 except that 0.9547 g (3.245 mmol) of aBPDA was added instead of BPAF. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-2) of 8.0 g of solid content powder.
• PAI-2 polyamide-imide copolymer
• Example 3 A polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.007 g (3.245 mmol) of sODPA was added instead of BPAF. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-3) of 7.9 g of solid content powder. The polystyrene-equivalent weight average molecular weight by GPC was 407,000.
• Example 4 A polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.442 g (3.245 mmol) of 6FDA was added instead of BPAF. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-4) of 8.3 g of solid content powder.
• the polystyrene-equivalent weight average molecular weight by GPC was 311,000.
• Example 1 A polyamide-imide solution was obtained in the same manner as in Example 1 except that 0.9547 g (3.245 mmol) of sBPDA was added instead of BPAF. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-5) of 8.2 g of solid content powder. The polystyrene-equivalent weight average molecular weight by GPC was 625,000.
• a polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.488 g (3.245 mmol) of BPAF and 0.9547 g (3.245 mmol) of aBPDA were added instead of aODPA and BPAF. ..
• the obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-6) of 7.5 g of solid content powder.
• the polystyrene-equivalent weight average molecular weight by GPC was 114,000.
• Example 3 As the tetracarboxylic dianhydride, a polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.488 g (3.245 mmol) of BPAF and 1.007 g (3.245 mmol) of sOPDA were added instead of aODPA and BPAF. .. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-7) of 7.3 g of solid content powder. The polystyrene-equivalent weight average molecular weight by GPC was 100,000.
• a polyamide-imide solution was obtained in the same manner as in Example 1 except that 0.9547 g (3.245 mmol) of aBPDA and 1.007 g (3.245 mmol) of sODPA were added instead of aODPA and BPAF. ..
• the obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-8) of 7.0 g of solid content powder.
• the polystyrene-equivalent weight average molecular weight by GPC was 97,000.
• Example 5 As the tetracarboxylic dianhydride, a polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.007 g (3.245 mmol) of sODPA and 1.441 g (3.245 mmol) of 6FDA were added instead of aODPA and BPAF. .. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-9) of 8.4 g of solid content powder. The polystyrene-equivalent weight average molecular weight by GPC was 478,000.
• a polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.007 g (3.245 mmol) of 6FDA and 0.9547 g (3.245 mmol) of sBPDA were added instead of aODPA and BPAF. ..
• the obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-10) of 8.0 g of solid content powder.
• the polystyrene-equivalent weight average molecular weight by GPC was 179,000.
• Example 7 As the tetracarboxylic dianhydride, a polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.007 g (3.245 mmol) of sODPA and 0.9547 g (3.245 mmol) of sBPDA were added instead of aODPA and BPAF. .. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-11) of 8.3 g of solid content powder. The polystyrene-equivalent weight average molecular weight by GPC was 593,000.
• a polyamide-imide solution was obtained in the same manner as in Example 1 except that 0.9547 g (3.245 mmol) of aBPDA and 0.9547 g (3.245 mmol) of sBPDA were added instead of aODPA and BPAF. ..
• the obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-12) of 7.9 g of solid content powder.
• the polystyrene-equivalent weight average molecular weight by GPC was 124,000.
• Example 9 As the tetracarboxylic dianhydride, a polyamide-imide solution was obtained in the same manner as in Example 1 except that 0.9547 g (3.245 mmol) of aBPDA and 1.441 g (3.245 mmol) of 6FDA were added instead of aODPA and BPAF. .. The obtained polyamide imide solution was purified in the same manner as in Example 1 to obtain 8.1 g of solid content powder polyamide imide copolymer (PAI-13). The polystyrene-equivalent weight average molecular weight by GPC was 77,000.
• Example 11 As the tetracarboxylic dianhydride, a polyamide-imide solution was obtained in the same manner as in Example 1 except that 1.488 g (3.245 mmol) of BPAF and 1.441 g (3.245 mmol) of 6FDA were added instead of aODPA and BPAF. .. The obtained polyamide-imide solution was purified in the same manner as in Example 1 to obtain a polyamide-imide copolymer (PAI-15) of 7.8 g of solid content powder. The polystyrene-equivalent weight average molecular weight by GPC was 429,000.
• Table 1 shows the molar ratios of the components constituting each polyamide-imide copolymer obtained as described above.
• a resin varnish was prepared by dissolving 5.0 g of each polyamide-imide obtained as described above in 45 g of DMAc. Next, it was applied onto a glass plate using a table coater (AFA-standard manufactured by Cortec), and in an inert gas oven (INL-45N1 manufactured by Yamato Kagaku Co., Ltd.) at 70 ° C. for 1 hour, and then at 250 ° C. for 1 hour. A film was formed by drying and peeling from a glass plate. The film thickness of the obtained film is as shown in Table 1 below. The following evaluation was performed using each of the obtained films as an evaluation sample.
• ⁇ YI value (yellow index) evaluation> Cut each film to a size of 30 mm x 30 mm, obtain the YI value using a spectrocolorimeter (CM-5, manufactured by Konica Minolta Co., Ltd.) in accordance with ASTM E313, and obtain the YI value according to the following evaluation criteria.
• CM-5 spectrocolorimeter
• YI value is 2 or more and less than 3 ⁇ : YI value is 3 or more
• the evaluation results are as shown in Table 1 below.
• ⁇ Film wettability> The contact angle with water on the surface of each film in contact with the glass plate was measured using a contact angle meter (DM300) manufactured by KYOWA INTERFACE SCIENCE. Based on the measured contact angle, the wettability of the film was evaluated according to the following evaluation criteria. ⁇ : Water contact angle is 55 degrees or less ⁇ : Water contact angle is more than 55 degrees, 65 degrees or less ⁇ : Water contact angle is more than 65 degrees The evaluation results are as shown in Table 1 below.
• a decorative coloring material is applied to the surface of each film in contact with the glass plate by screen printing so that the film thickness after drying is 2 to 3 ⁇ m, and the colored coating film is heated and dried at 80 ° C. for 30 minutes. Was formed, and an adhesion evaluation sample was obtained.
• the decorative coloring material was prepared as follows.
• the adhesion between the film and the colored coating film was evaluated in accordance with JIS K 5600-5-6 (ISO2409). Specifically, after using a single-edged blade to make 100-square grid-shaped cuts in the colored coating film at 1 mm intervals, affix "cellotape” (registered trademark), and then draw cellophane tape (registered trademark). The state of the peeled and colored coating film was visually confirmed, and evaluation was performed based on the evaluation criteria of JIS K 5600-5-6 (ISO2409) (6 grades of 0 to 5 in descending order of adhesion). The evaluation results are as shown in Table 1 below.
• the imide copolymer (Examples 1 to 4) is derived from a polyamide-imide copolymer (Comparative Example 1) in which an imide structural unit (unit I-1) and another imide structural unit (sBPDA) are used in combination, or aODPA. It can be seen that all of the optical properties, mechanical properties, wettability, and adhesion are excellent with respect to the polyamide-imide copolymers having no structural unit (Comparative Examples 2 to 11).

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