Polyimide precursor

Abstract

The present application provides a polyimide precursor that contains a high molecular weight polyamic acid and thereby can simultaneously realize a low dielectric constant and mechanical properties under severe conditions such as light resistance, heat resistance, insulation properties, and high temperatures, a method for producing the polyamic acid, a method for increasing the molecular weight of the polyamic acid, a film containing the precursor, and a display device in which the film is attached to a substrate.

Description

Technical Field

[0001] This application relates to a polyimide precursor containing a polyamic acid, a method for producing the polyamic acid, a method for increasing the molecular weight of the polyamic acid, a film containing the precursor, and a display device in which the film is attached to a substrate.

Background Art

[0002] Generally, polyimide (PI) is a polymer of imide monomers formed by solution polymerization of dianhydrides and diamines or diisocyanates, and has excellent mechanical properties such as strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring. Furthermore, polyimide has excellent electrical properties such as insulation properties and low dielectric constant, and has attracted attention as a high-functional polymer material applicable to a wide range of industrial fields such as electronics, communication, and optics.

[0003] Here, polyimide refers to a high heat-resistant resin produced by solution polymerization of a dianhydride monomer and a diamine monomer to produce a polyamic acid, and then subjecting it to ring-closing dehydration at a high temperature to imidize it.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This application provides a polyimide precursor that can simultaneously exhibit a low dielectric constant, light resistance, heat resistance, insulation properties, and mechanical properties under severe conditions such as high temperature, including a high molecular weight polyamic acid, a method for producing the polyamic acid, a method for increasing the molecular weight of the polyamic acid, a film containing the precursor, and a display device in which the film is attached to the lower part of a substrate.

Means for Solving the Problems

[0005] This application relates to a polyimide precursor. For example, the polyimide precursor may be a polyimide varnish that is applied to a coating target and then imidized by thermal curing. The polyimide precursor can embody the excellent insulating properties, adhesion, heat resistance, mechanical strength, light resistance, and flexibility of polyimide, and can be used as a substrate adhesion material for displays.

[0006] An exemplary polyimide precursor according to this application comprises a polyamic acid containing a dianhydride monomer and a diamine monomer as polymerization units, and an organic solvent containing at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA).

[0007] Furthermore, the weight-average molecular weight of the polyamic acid may be within the range of 40,000 to 100,000 g / mol, 45,000 to 90,000 g / mol, 48,000 to 80,000 g / mol, 50,000 to 75,000 g / mol, or 51,000 to 70,000 g / mol. In this application, the term "weight-average molecular weight" refers to the converted value relative to standard polystyrene measured by GPC (Gel permeation Chromatography).

[0008] The polyimide precursor according to the present invention may be a polyamic acid solution containing polyamic acid and an organic solvent. In the present invention, the terms polyimide precursor, polyamic acid solution, and polyimide varnish are interpreted as having the same meaning.

[0009] The polyamic acid may be produced by a polymerization reaction of a dianhydride monomer and a diamine monomer in the presence of the organic solvent. By polymerizing the polyamic acid of the present invention under the organic solvent, the weight-average molecular weight increases and can satisfy the aforementioned numerical range.

[0010] The polyimide precursor according to this application contains a high molecular weight polyamic acid that satisfies the aforementioned numerical range, thereby providing a polyimide with improved mechanical properties and heat resistance during imidation.

[0011] In one example, the organic solvent may be N,N-dimethylpropionamide (DMPA). On the other hand, the organic solvent does not have to contain N-methyl-2-pyrrolidone (NMP). Polyamic acids polymerized in the presence of N-methyl-2-pyrrolidone may not satisfy the weight-average molecular weight within the aforementioned numerical range.

[0012] In one specific example, the polydispersity index (PDI) of the polyamic acid may be in the range of 1 to 5. For example, the polydispersity index (PDI) of the polyamic acid may be in the range of 1.1 to 4.9, 1.2 to 4.5, 1.3 to 4.3, 1.4 to 4.0, 1.5 to 3.8, 1.6 to 3.4, 1.7 to 3.2, 1.8 to 3.0, 1.9 to 2.9, 2 to 2.8, or 2.1 to 2.7.

[0013] In one specific example, the dianhydride monomer may be an aromatic tetracarboxylic dianhydride. For example, the dianhydride monomer contains at least one compound represented by the following chemical formula 1.

[0014] [ka]

[0015] In the above chemical formula 1, X is a tetravalent aliphatic ring group, a tetravalent heteroaliphatic ring group, a tetravalent aromatic ring group, or a tetravalent heteroaromatic ring group, and the carbon atom of the carbonyl group in chemical formula 1 is linked to the ring constituent atoms of the aliphatic ring group, heteroaliphatic ring group, aromatic ring group, or heteroaromatic ring group.

[0016] The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group are

[0017] Is it a monoring?

[0018] They join together to form a polyring, or

[0019] Single bond, substituted or unsubstituted alkylene group, substituted or unsubstituted alkylidene group, substituted or unsubstituted alkenylene group, substituted or unsubstituted alkynylene group, substituted or unsubstituted arylene group, -O-, -S-, -C(=O)-, -S(=O)2- and -Si(R a The group is linked by a linking group which contains at least one divalent substituent selected from the group consisting of )2-, where R a These are hydrogen atoms or alkyl groups.

[0020] Preferably, X is phenyl, biphenyl, [ka] Alternatively, M is an aliphatic ring group, wherein M includes at least one selected from the group consisting of a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O)2-.

[0021] As used herein, the term "aliphatic cyclic group" means an aliphatic cyclic group having 3 to 30 carbon atoms, 4 to 25 carbon atoms, 5 to 20 carbon atoms, or 6 to 16 carbon atoms, unless otherwise specified. Specific examples of the tetravalent aliphatic cyclic group include, for example, groups obtained by removing 4 hydrogen atoms from rings such as cyclohexane ring, cycloheptane ring, cyclodecane ring, cyclododecane ring, norbornane ring, isobornane ring, adamantane ring, cyclododecane ring, dicyclopentane ring, and the like.

[0022] As used herein, the term "aromatic cyclic group" means an aromatic cyclic group having 4 to 30 carbon atoms, 5 to 25 carbon atoms, 6 to 20 carbon atoms, or 6 to 16 carbon atoms, unless otherwise specified. The aromatic ring may be a monocyclic ring or a condensed ring. Specific examples of the tetravalent aromatic hydrocarbon cyclic group include, for example, groups obtained by removing 4 hydrogen atoms from benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, or pyrene ring.

[0023] As used herein, the term "arylene group" means a divalent organic group derived from the aromatic cyclic group.

[0024] As used herein, the term "heterocyclic group" includes heteroaliphatic cyclic groups and heteroaromatic cyclic groups.

[0025] As used herein, the term "heteroaliphatic cyclic group" means a cyclic group in which at least one of the carbon atoms of the aliphatic cyclic group is replaced by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus.

[0026] As used herein, the term "heteroaromatic cyclic group" means a cyclic group in which at least one of the carbon atoms of the aromatic cyclic group is replaced by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus, unless otherwise specified. The heteroaromatic cyclic group may be a monocyclic ring or a condensed ring.

[0027] The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group may each be independently substituted with at least one substituent selected from the group consisting of halogens, hydroxyl groups, carboxyl groups, halogen-substituted or unsubstituted C1-C4 alkyl groups, and C1-C4 alkoxy groups.

[0028] In this specification, the term “single bond” means a bond that connects two atoms without any other atoms. For example, in the chemical formula 1 above, X is [ka] Here, if M is a single bond, both aromatic rings may be directly linked to each other.

[0029] In this specification, the term "alkyl group" means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0030] In this specification, the term "alkenyl group" means an alkenyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkenyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0031] In this specification, the term "alkynyl group" means an alkynyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkynyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0032] In this specification, the term "alkylene group" means an alkylene group having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 10 carbon atoms, or 2 to 8 carbon atoms, unless otherwise specified. The alkylene group may have a linear, branched, or cyclic structure as a divalent organic group from which two hydrogen atoms have been removed from different carbon atoms, and may optionally be substituted with at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0033] In this specification, the term "alkylidene group" means an alkylidene group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, or 1 to 8 carbon atoms, unless otherwise specified. The alkylidene group may have a linear, branched, or cyclic structure as a divalent organic group in which two hydrogen atoms have been removed from one carbon atom, and may optionally be substituted with at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0034] In this specification, the term "alkoxy group" means an alkoxy group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkoxy group may have a linear, branched, or cyclic alkyl group, and the alkyl group may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0035] In this specification, the term "alkylamine group" includes monoalkylamines (-NHR) or dialkylamines (-NR2) unless otherwise specified, where R independently represents an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0036] In this specification, the term "alkylamide" includes monoalkylamides (-C(O)NHR) or dialkylamides (-C(O)NR2) unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0037] In this specification, the terms "thioether group" or "sulfide" mean -SR unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0038] In this specification, the term "sulfoxide" means -S(O)R unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0039] In this specification, the term "carbonyl" includes -C(O)R unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0040] In this specification, the term "ester" includes -C(O)OR or -OC(O)R unless otherwise specified, where R independently represents an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0041] The aliphatic tetracarboxylic dianhydrides satisfying the aforementioned chemical formula 1 are 1,2,4,5-cyclohexanetetracarboxylic dianhydride (i.e., HPMDA), bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BODA), 1,2,3,4-cyclohexanetetracarboxylic dianhydride (CHMDA), bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BHDA), butane-1,2,3,4-tetracarboxylic dianhydride (BTD), and bicyclo-[2.2.2]octane. To-7-ene-2-exo,3-exo,5-exo,6-exo-2,3:5,6-dianhydride (BTA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo[4.2.0]octane-3,4,7,8-tetracarboxylic dianhydride (OTD), norbornane-2-spiro-α-cyclohexanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (ChODA), cyclopentanonebis-spironorbornanetetracarboxylic dianhydride (CpODA), bicyclo[2.2.1]Heptane-2,3,5-tricarboxyl-5-acetic acid dianhydride (BSDA), dicyclohexyl-3,3',4,4'-tetracarboxylic acid dianhydride (DCDA), dicyclohexyl-2,3'-3,4'-tetracarboxylic acid dianhydride (HBPDA), 5,5'-oxybis(hexahydro-1,3-isobenzoflangion) (HODPA), 5,5'-methylenebis(hexahydro-1,3-isobenzoflangion) (HMDPA), 3,3'-(1,4-piperazinediyl)bis[dihydro-2,5-flangion] (PDSA), 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride (DOCDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinate di Examples include anhydrides (TDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-6-methyl-1-naphthalenesuccinate dianhydride (MTDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-6-fluoro-1-naphthalenesuccinate dianhydride (FTDA), 3,3,3',3'-tetramethyl-1,1'-spirobisindan-5,5',6,6'-tetracarboxylic anhydride (SBIDA), 4,4,4',4'-tetramethyl-3,3',4,4'-tetrahydro-2,2'-spirobi[flo[3,4-g]chromene]-6,6',8,8'-tetraone (SBCDA), and 9,10-difluoro-9,10-bis(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetracarboxylic anhydride (6FDA). .

[0042] The aromatic tetracarboxylic dianhydrides satisfying the aforementioned chemical formula 1 are pyromellitic dianhydride (i.e., PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (i.e., BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (i.e., α-BPDA), oxydiphthalic dianhydride (i.e., ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (i.e., DSDA), bis(3,4-dicarboxyphenyl) sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (i.e., BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, and 2,2-bis(3,4-dicarboxyphenyl) Phenyl)propane dianhydride, p-phenylenebis(trimellitic acid monoester anhydride), p-biphenylenebis(trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic acid dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic acid dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy) Examples include benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, or 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride (6-FDA).

[0043] The compound represented by chemical formula 1 is preferably an aromatic tetracarboxylic dianhydride, and may particularly include 3,3',4,4'-biphenyltetracarboxylic dianhydride (i.e., BPDA) or 2,3,3',4'-biphenyltetracarboxylic dianhydride (i.e., α-BPDA).

[0044] As an example, the diamine monomer may contain at least one compound represented by the following chemical formula 2.

[0045] [ka]

[0046] In the above chemical formula 2, one of B1 to B5 is an amino group, and the remaining ones represent hydrogen, halogen, hydroxyl group, carboxyl group, or alkyl group substituted or unsubstituted for a halogen.

[0047] Furthermore, diamine monomers that may be used in the production of polyamic acid solutions are aromatic diamines, and examples can be given by classifying them as follows.

[0048] 1) Diamines that structurally have one benzene ring and have a relatively rigid structure, such as 1,4-diaminobenzene (i.e., paraphenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, or 3,5-diaminobenzoic acid (i.e., DABA),

[0049] 2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (i.e., oxydianiline, ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenyl Phenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl) sulfide, 4,4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (i.e., o-tolidine), 2,2'-dimethylbenzidine (i.e., m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3, 3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane Diamines that structurally have two benzene rings, such as tan, 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, and 4,4'-diaminodiphenyl sulfoxide,

[0050] 3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-amino)phenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (i.e., TPE-Q), 1,4-bis(4-aminophenoxy)benzene (i.e., TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone Diamines that structurally have three benzene rings, such as benzene, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, and 1,4-bis[2-(4-aminophenyl)isopropyl]benzene,

[0051] 4) 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl] ether, bis[3-(4-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] ether, bis[4-(4-aminophenoxy)phenyl] ether, bis[3-(3-aminophenoxy)phenyl] ketone, bis[3-(4-aminophenoxy] [4-(3-aminophenoxy)phenyl] ketone, bis[4-(3-aminophenoxy)phenyl] ketone, bis[4-(4-aminophenoxy)phenyl] ketone, bis[3-(3-aminophenoxy)phenyl] sulfide, bis[3-(4-aminophenoxy)phenyl] sulfide, bis[4-(3-aminophenoxy)phenyl] sulfide, bis[4-(4-aminophenoxy)phenyl] sulfone, bis[3-(3-aminophenoxy)phenyl] sulfone, bis[4-(3-aminophenoxy)phenyl] [Nyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane Diamines that structurally have four benzene rings, such as bis(((((3-aminophenoxy)phenyl))propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0052] The diamine monomers may be used individually or in combination of two or more as needed. This application may include, for example, 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, or 4,4'-methylenediamine (MDA), taking into consideration their bond dissociation energies. Preferably, the compound represented by chemical formula 2 may include 1,4-diaminobenzene (PPD).

[0053] In one specific example, the polyimide precursor may contain 5-40% by weight, 10-30% by weight, or 15-20% by weight of solids based on the total weight. This application aims to control the increase in viscosity by adjusting the solids content of the polyimide precursor, while also preventing an increase in manufacturing costs and process time that would otherwise be required to remove a large amount of solvent during the curing process.

[0054] In one specific example, the polyamic acid may be in the range of 1 to 50% by weight based on the total solid content. For example, the range may be 3 to 40% by weight, 5 to 30% by weight, or 10 to 20% by weight. If it is less than 1% by weight, the consistency of the varnish coating layer decreases, and conversely, if it exceeds 40% by weight, the storage stability deteriorates.

[0055] The polyimide precursor of this application may contain a high molecular weight polyamic acid and may also have low viscosity properties. The polyimide precursor of this application is measured at a temperature of 23°C and 1 s. -1The viscosity measured under the shear rate conditions may be 50,000 cP or less, 40,000 cP or less, 30,000 cP or less, 20,000 cP or less, 10,000 cP or less, 9,000 cP or less, 5,000 cP or less, 4,000 cP or less, or 3,000 cP or less. The lower limit is not particularly limited, but may be 500 cP or more, or 1,000 cP or more. In one specific example, the polyimide precursor of this application may be in the range of 500 to 10,000 cP. The viscosity may be measured, for example, at a temperature of 23°C using Haake's MARS40. By adjusting the viscosity range, this application can provide a polyimide precursor with excellent processability and ease of product application.

[0056] This application relates to a method for producing polyamic acid. The production method can provide polyamic acid having a high weight-average molecular weight by polymerizing polyamic acid under a specific solvent. Detailed explanations that overlap with the above are omitted below.

[0057] Specifically, the above-mentioned manufacturing method may include a step of polymerizing a dianhydride monomer and a diamine monomer using an organic solvent containing at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA).

[0058] This application relates to a method for further increasing the molecular weight of polyamic acids. Specifically, this application relates to a method for increasing the molecular weight of polyamic acids containing polymerization units derived from dianhydride monomers and diamine monomers using an organic solvent containing at least one of the aforementioned compounds.

[0059] By polymerizing under the aforementioned organic solvent, the weight-average molecular weight of the polyamic acid increases, and compared to the case where NMP is used as the organic solvent, the weight-average molecular weight increases in an environmentally friendly manner, thereby providing a polyimide with improved mechanical properties and heat resistance during imidization.

[0060] More specifically, the weight-average molecular weight of the polyamic acid may be in the range of 40,000 g / mol to 100,000 g / mol.

[0061] This application further relates to a film comprising the aforementioned polyimide precursor. The film may be attached to a substrate of a display device.

[0062] Therefore, the thickness of the film may be formed to be thin enough to be suitable for attachment to the product, for example, the thickness may be within the range of 1-100 μm, 5-90 μm, 5-80 μm, 5-70 μm, 10-100 μm, 10-90 μm, 10-80 μm, 10-70 μm, 10-60 μm, 10-50 μm, 20-100 μm, 20-90 μm, 20-80 μm, or 20-70 μm, 20-60 μm, or 20-50 μm.

[0063] Furthermore, by adjusting the composition and content ratio of the polyimide precursor mentioned above, the film's various physical properties can be controlled within the following numerical range.

[0064] For example, the film is UTM (Universal Testing The elongation measured using the machine may be 100% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, or 25% or less; the tensile strength may be 700 MPa or less, 650 MPa or less, 600 MPa or less, 550 MPa or less, 500 MPa or less, 450 MPa or less, 400 MPa or less, 350 MPa or less, 300 MPa or less, 250 MPa or less, 200 MPa or less, or 150 MPa or less; and the modulus may be 12 Gpa or less, 11 Gpa or less, 10 Gpa or less, 9 Gpa or less, 8 Gpa or less, 7 Gpa or less, 6 Gpa or less, 5 Gpa or less, 4 Gpa or less, or 3 Gpa or less. The measurement may be performed using a UTM device under the conditions of a width of 20 mm, a grip distance of 50 mm, and a crosshead speed of 20 min / min.

[0065] Furthermore, the film may have a coefficient of thermal expansion (CTE) measured using a Thermo Mechanical Analysis (TMA) device within the ranges of 0.1 ppm / °C to 50 ppm / °C, 0.5 ppm / °C to 50 ppm / °C, 1 ppm / °C to 50 ppm / °C, 5 ppm / °C to 50 ppm / °C, 10 ppm / °C to 45 ppm / °C, 15 ppm / °C to 40 ppm / °C, 20 ppm / °C to 40 ppm / °C, 25 ppm / °C to 40 ppm / °C, or 25 ppm / °C to 35 ppm / °C. The measurement may be performed using a TMA device at a temperature range of 50 to 200°C with a heating rate of 10°C / min while applying a load of 0.02 N.

[0066] Furthermore, the 1% thermal decomposition temperature (td) of the film, measured using a TGA (Thermo Gravimetric analysis) apparatus, may be within the range of 300-600°C, 350-600°C, 400-600°C, 450-600°C, 500-600°C, or 540-600°C. The measurement may be performed by preheating to 150°C and then measuring using a TGA apparatus at a heating rate of 10°C / min for 30 minutes.

[0067] This application further relates to a display device. For example, the device includes a substrate and the aforementioned film attached to the substrate. The type of the display device is not particularly limited and can be applied to a variety of types without restriction. The display device has excellent heat resistance, light resistance and electrical properties because the aforementioned film is attached to the bottom of the substrate. [Effects of the Invention]

[0068] This application provides a polyimide precursor that simultaneously embodies a low dielectric constant and mechanical properties under harsh conditions such as light resistance, heat resistance, insulation, and high temperature by containing a high molecular weight polyamic acid, a method for producing the polyamic acid, a method for increasing the molecular weight of the polyamic acid, a film containing the precursor, and a display device in which the film is mounted on a substrate. [Modes for carrying out the invention]

[0069] The present application will be specifically described through the following embodiments, but the scope of this application is not limited by the embodiments described below.

[0070] Examples In a 500 mL glass reaction vessel equipped with a stirrer, nitrogen gas introduction and discharge pipes, 417 g of N,N-dimethylpropionamide (DMPA), 21.7 g (0.2 mol) of 1,4-diaminobenzene (PPD), and 59.1 g (0.2 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added, and the polymerization reaction was carried out at 25°C to produce a polyamic acid solution with a solid content of 15%.

[0071] Comparative Example In a 500 mL glass reaction vessel equipped with a stirrer, nitrogen gas introduction and discharge pipes, 417 g of N-methyl-2-pyrrolidone (NMP), 21.7 g (0.2 mol) of 1,4-diaminobenzene (PPD), and 59.1 g (0.2 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added, and the polymerization reaction was carried out at 25°C to produce a polyamic acid solution (polyimide precursor) with a solid content of 15%.

[0072] 1. Viscosity measurement The viscosity of the polyamic acid solutions prepared in the examples and comparative examples was measured at a temperature of 23°C using a Haake MARS40, and the results are shown in Table 1 below.

[0073] [Table 1]

[0074] 2. Measurement of weight-average molecular weight (Mw) The polyamic acid solutions of the examples and comparative examples were repeatedly prepared to produce four samples each (Examples: Samples 1-4, Comparative Examples: Samples 5-8).

[0075] The weight-average molecular weight of polyamic acid in each sample was measured using GPC, and the results are shown in Table 2 below.

[0076] [Table 2]

[0077] As shown in Table 2 above, it was confirmed that the example using DMPA as the solvent had a higher weight-average molecular weight compared to the comparative example using NMP as the solvent.

Claims

1. A polyamic acid comprising 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 1,4-diaminobenzene (PPD) as polymerization units, A polyimide precursor comprising dimethylpropionamide (DMPA), The weight-average molecular weight of the polyamic acid is in the range of 40,000 g / mol to 70,000 g / mol. The polyimide precursor contains 15 to 20% by weight of solids, based on the total weight. The polyimide precursor is a polyimide precursor whose viscosity, measured at a temperature of 23°C and a shear rate of 1 s⁻¹, is in the range of 5,000 cp or less.

2. The polyamic acid is a polyimide precursor according to claim 1, wherein the polyamic acid has a polydispersity index (PDI) in the range of 1 to 5.

3. The polyimide precursor according to claim 1, wherein the polyamic acid content is in the range of 1 to 50% by weight based on the total solid content.

4. A film comprising the polyimide precursor described in claim 1.

5. The film according to claim 4, wherein the thickness is in the range of 1 to 100 μm.

6. The film according to claim 4, wherein the elongation is 100% or less, the tensile strength is 700 MPa or less, and the modulus is 12 GPa or less.

7. The film according to claim 4, wherein the coefficient of thermal expansion (CTE) is in the range of 0.1 ppm / °C to 50 ppm / °C.

8. The film according to claim 4, wherein the 1% thermal decomposition temperature (td) is in the range of 300 to 600°C.

9. circuit board and The film according to claim 4 attached to the substrate, Display devices, including

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