Polyamic acid composition

Abstract

The present application provides a polyamic acid composition capable of realizing a polyimide film having environmentally friendly surface properties and durability, and capable of realizing a polyimide film having optical properties and durability equivalent to or superior to existing polyimide films produced using environmentally friendly organic solvents but using hazardous substances that are defined as hazardous substances; a polyimide precursor including a polymer of the polyamic acid composition; a polyimide film including a cured product of the polyimide precursor; and a method for producing the polyimide precursor.

Description

[Technical Field]

[0001] The present application relates to a polyamic acid composition, a polyimide precursor containing a polymer of the polyamic acid composition, a polyimide film containing a cured product of the polyimide precursor, and a method for producing the polyimide precursor. [Background technology]

[0002] Generally, polyimide (PI) is a polymer of imide monomers formed by solution polymerization of dianhydrides and diamines or diisocyanates. Due to the chemical stability of the imide ring, it has excellent mechanical properties such as strength, chemical resistance, weather resistance, and heat resistance. Furthermore, due to its excellent electrical properties such as insulating properties and low dielectric constant, polyimide is gaining attention as a highly functional polymer material applicable to a wide range of industrial fields, including electronics, communications, and optics.

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

[0004] On the other hand, existing solution polymerization of polyamic acid was carried out in an organic solvent, but many of the organic solvents used, such as N-methyl-pyrrolidone (NMP), dimethylformamide (DMF), and N,N'-dimethylacetamide (DMAc), are designated as hazardous substances, and have the disadvantages of high purification costs and environmental issues due to the difficulty of achieving 100% purification.

[0005] Recently, attempts have been made to use environmentally friendly solvents, but these solvents have the problem of being inferior in surface properties and durability compared to existing organic solvents. Summary of the Invention [Problem to be solved by the invention]

[0006] The present application provides a polyamic acid composition capable of realizing a polyimide film having environmentally friendly surface properties and durability, and capable of realizing a polyimide film having optical properties and durability equivalent to or superior to existing polyimide films produced using hazardous substances even when an environmentally friendly organic solvent is used; a polyimide precursor including a polymer of the polyamic acid composition; a polyimide film including a cured product of the polyimide precursor; and a method for producing the polyimide precursor. [Means for solving the problem]

[0007] The present application relates to a polyamic acid composition. The polyamic acid composition contains the components described below, and thereby can provide an environmentally friendly polyimide film having excellent surface properties and durability.

[0008] An example polyimide precursor according to the present application includes a polyamic acid having polymerized units derived from a dianhydride monomer and a diamine monomer; an organic solvent satisfying the following Chemical Formula 1; and an end-capping agent having at least one functional group reactive with the end of the polyamic acid. [ka]

[0009] In the above Chemical Formula 1, at least one of A1 to A3 is an alkylamine group, a hydroxy group, an alkoxy group, a thiol group, a thiol ether group, an alkyl group, or a heterocyclic group.

[0010] In one specific example, A1 to A3 each independently represent an alkyl group having 1 to 4 carbon atoms which is substituted or unsubstituted with a hydroxy group, more specifically, A1 is an alkyl group having 1 to 4 carbon atoms which is substituted or unsubstituted with a hydroxy group, and A2 and A3 each independently represent an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms represented by A1 to A3 include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

[0011] A1 is preferably a methyl group, an ethyl group, a propyl group or an isopropyl group, and particularly preferably an ethyl group, a propyl group or an isopropyl group.

[0012] Furthermore, A2 and A3 are preferably independently a methyl group or an ethyl group, and it is particularly preferable that both are a methyl group.

[0013] The polyamic acid composition according to the present invention may be a polyamic acid varnish containing a polyamic acid, an organic solvent, and a first end-capping agent or a second end-capping agent.

[0014] The polyamic acid may be prepared by a polymerization reaction of a dianhydride monomer and a diamine monomer in the presence of an organic solvent represented by Chemical Formula 1, and the polyamic acid composition may be prepared by adding an end-capping agent to the polyamic acid prepared by the polymerization reaction.

[0015] The polyamic acid composition can be prepared into a polyimide precursor, as described below, by reacting a polyamic acid with an end-capping agent. Polyamic acid compositions and polyimide precursors are classified according to whether or not the polyamic acid is end-capped. The polyamic acid in a polyamic acid composition is unend-capped, while the polyamic acid in a polyimide precursor is end-capped. To distinguish between polyamic acids with and without end-capping, the present invention refers to end-capped polyamic acids as modified polyamic acids.

[0016] The polyamic acid composition of the present invention can provide a polyimide precursor containing a modified polyamic acid by reacting a polyamic acid with an end-capping agent, and the polyimide precursor can provide a polyimide film having excellent optical properties, excellent surface properties, and durability (also referred to as mechanical strength) after curing.

[0017] In one embodiment, the compound represented by Chemical Formula 1 may have a negative (-) octanol / water partition coefficient (Log P) calculated by the following Equation 1: [Number 1] Log P = Log (Kow) Kow = Co / Cw In the above mathematical formula 1, Co is the concentration of the solute in octanol, and Cw is the concentration of the solute in water.

[0018] The partition coefficient can be calculated at 25°C using the ACD / LogP module of the ACD / Percepta platform from ACD / Labs, Inc. The ACD / LogP module uses an algorithm based on the QSPR (Quantitative Structure-Property Relationship) methodology using the 2D structure of the molecule. However, because the partition coefficient is an experimental value, it cannot be ruled out that it may be measured as a positive value depending on the measurement method or algorithm used.

[0019] Examples of the compound represented by Formula 1 having a negative partition coefficient include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and N,N-dimethylpropionamide (DMPA).

[0020] Considering the environment, the organic solvent may be N,N-dimethylpropionamide (DMPA) in the compound represented by Chemical Formula 1. DMPA is an environmentally friendly organic solvent that can be disposed of without a separate purification process after the polymerization reaction, which leads to cost reduction.

[0021] On the other hand, in the case of polyamic acid polymerized in DMPA solvent, the polyimide produced in film form after curing (also called imidization) has drawbacks such as poor surface properties, a low thermal decomposition temperature, and poor mechanical properties. However, the modified polyamic acid produced by polymerization of the polyamic acid composition of the present invention shows the effect of improving the above drawbacks of the polyimide produced in film form after curing.

[0022] In addition, in the case of polyamic acid polymerized in DMPA solvent, the optical properties and durability of the polyimide film produced after curing are inferior to those of polyimide films produced using organic solvents designated as hazardous substances, such as NMP, DMF, or DMAc.

[0023] The polyamic acid composition according to the present invention contains an end-capping agent having a specific functional group that reacts with the terminal of the polyamic acid, thereby improving and resolving the above-mentioned problems that occur when using DMPA solvent.

[0024] In addition, the polyimide precursor according to the present invention may be free of organic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). NMP, DMF, and DMAc are classified as hazardous substances, which require additional costs for purification, are difficult to purify completely, and may cause environmental problems during the purification process.

[0025] In one embodiment, the end-capping agent may include at least one selected from the group consisting of a first end-capping agent that is an anhydride-based compound and a second end-capping agent that is a diamine-based compound having at least one siloxane group.

[0026] In one example, the first end-capping agent may include an anhydride compound having an aliphatic cyclic group, a heterocyclic group, or an aromatic cyclic group. The anhydride compound having the cyclic group has excellent compatibility with polyamic acid and terminal reaction efficiency. The anhydride group of the anhydride compound reacts with the terminal of the polyamic acid to produce a modified polyamic acid.

[0027] In another example, the anhydride compound may include one or more functional groups selected from the group consisting of a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a hydroxyl group, a carboxyl group, an isocyanate group, and a cyanate group. The functional groups may form crosslinks between polyamic acid chains during the imidization (thermal curing) process of the polyamic acid, ultimately improving the bonding strength between polyimide chains and various physical properties such as surface characteristics and durability.

[0028] Specifically, the anhydride-based compound may include at least one selected from the group consisting of phthalic anhydride (PA), maleic anhydride (MA), nadic anhydride (NA), 4-phenylethynylphthalic anhydride (4-PEPA), and 4-ethylphthalic anhydride (EPA).

[0029] In one specific example, the content of the end-capping agent may be within a range of 0.01 to 20 mol% relative to 100 mol% of the diamine monomer, for example, 0.01 to 18 mol%, 0.01 to 16 mol%, 0.01 to 14 mol%, 0.01 to 12 mol%, 0.01 to 10 mol%, 0.05 to 20 mol%, 0.05 to 18 mol%, 0.05 to 16 mol%, 0.05 to 15 mol%, 0.05 to 14 mol%, 0.05 to 12 mol%, 0.05 to 16 mol%, 0.05 to 15 mol%, 0.05 to 14 mol%, 0.05 to 12 mol%, 0.05 to 18 ... The end-capping agent content may be within the ranges of 0.05 to 10 mol%, 0.05 to 5 mol%, 0.1 to 20 mol%, 0.1 to 18 mol%, 0.1 to 16 mol%, 0.1 to 15 mol%, 0.1 to 14 mol%, 0.1 to 12 mol%, 0.1 to 10 mol%, 0.1 to 5 mol%, 0.2 to 18 mol%, 0.2 to 16 mol%, 0.2 to 14 mol%, 0.2 to 12 mol%, or 0.2 to 10 mol%. By adjusting the content of the end-capping agent within the above ranges, a polyimide film exhibiting excellent optical properties, surface properties, and mechanical properties can be realized.

[0030] In the case of the second end-capping agent, the amine group of the diamine compound reacts with the end of the polyamic acid. The diamine compound has excellent compatibility with polyamic acid and terminal reaction efficiency, and is capable of controlling the weight-average molecular weight of the polyamic acid. It also has the characteristic of being able to selectively react with the end of the polyamic acid only during thermal curing (or imidization), which improves and complements the disadvantages of using DMPA.

[0031] For example, the diamine-based compound may include a diamine-based compound having a silsesquioxane structure represented by the following Chemical Formula 2 or Chemical Formula 3. [ka] [Chemical formula 3] [R7SiO 3 / 2 ] m In the above Chemical Formula 2, n is an integer from 1 to 10, R1 to R4 each independently represent an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, R5 and R6 each independently represent a linking group containing one or more divalent substituents selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a substituted or unsubstituted arylene group, -O-, -S-, -C(=O)-, or -S(=O)2-; In the above Chemical Formula 3, m is an integer from 6 to 15; At least two of R7 are amine groups, and the rest are organic groups having 1 to 20 carbon atoms or halogen groups.

[0032] Examples of the organic group include alkyl groups such as methyl, ethyl, and propyl groups; halogen-containing groups such as trifluoromethyl groups; and alkoxy groups such as methoxy and ethoxy groups. Examples of halogen groups include fluoro groups.

[0033] In one embodiment, n is 1 to 4, R1 to R4 each independently represent an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, R5 and R6 may each independently be a single bond or a substituted or unsubstituted alkylene group.

[0034] More specifically, n is 1, R1 to R4 each independently represent a methyl group or a phenyl group; R5 and R6 may be propylene groups.

[0035] Specific examples of the diamine compound of Formula 2 or 3 include 1,3-Bis(3-aminopropyl)tetramethyldisiloxane (SIDA) and 3-Aminopropyl Me, di-Ph Siloxanes, polymers with Ph silsesquioxanes (PSIDA).

[0036] In one embodiment, the dianhydride monomer may be an aromatic tetracarboxylic dianhydride, for example, the dianhydride monomer may include at least one compound represented by the following formula 4: [ka] In the above Chemical Formula 4, [X] represents a tetravalent aliphatic cyclic group, a tetravalent aromatic cyclic group, or a tetravalent heterocyclic group, The aliphatic cyclic group, the aromatic cyclic group, or the heterocyclic group is Is it a single ring? is a fused ring; or a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a substituted or unsubstituted arylene group, -O-, -S-, -C(=O)- or -S(=O)2-, and -Si(R b )2-, wherein R b is hydrogen or an alkyl group.

[0037] Preferably, the [X] is [ka] , [ka] , or an aliphatic cyclic group, The 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-.

[0038] In this specification, unless otherwise specified, the term "aliphatic cyclic group" refers to 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. Specific examples of tetravalent aliphatic cyclic groups include groups in which four hydrogen atoms have been removed from a ring such as a cyclohexane ring, a cycloheptane ring, a cyclodecane ring, a cyclododecane ring, a norbornane ring, an isobornane ring, an adamantane ring, or a dicyclopentane ring.

[0039] In this specification, unless otherwise specified, the term "aromatic ring group" refers to an aromatic ring group having 4 to 30 carbon atoms, 5 to 25 carbon atoms, 6 to 20 carbon atoms, or 6 to 16 carbon atoms. The aromatic ring may be a monocyclic or fused ring. Examples of tetravalent aromatic hydrocarbon ring groups include groups in which four hydrogen atoms have been removed from a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, or a pyrene ring.

[0040] In this specification, the term "arylene group" means a divalent organic group derived from the above aromatic ring group.

[0041] As used herein, the term "heterocyclic group" includes heteroaliphatic cyclic groups and heteroaromatic cyclic groups.

[0042] As used herein, the term "heteroaliphatic cyclic group" refers to a cyclic group in which at least one carbon atom of the aliphatic cyclic group is replaced with one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus.

[0043] As used herein, unless otherwise specified, the term "heteroaromatic ring group" refers to a ring group in which at least one carbon atom of the aromatic ring group is replaced with one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus. The heteroaromatic ring group may be a monocyclic ring or a fused ring.

[0044] The aliphatic cyclic group, the heteroaliphatic cyclic group, the aromatic cyclic group, and the heteroaromatic cyclic group may each independently be substituted with one or more substituents selected from the group consisting of a halogen, a hydroxy group, a carboxy group, an alkyl group having 1 to 4 carbon atoms which is unsubstituted or substituted with a halogen, and an alkoxy group having 1 to 4 carbon atoms.

[0045] As used herein, the term "fused ring" refers to a ring formed by covalently bonding two or more atoms of two or more ring groups, and means that two or more aromatic rings are joined or linked to each other to form a polycyclic ring system, such as a fused aliphatic ring, a fused aromatic ring, a fused heteroaliphatic ring, a fused heteroaromatic ring, or a combination thereof.

[0046] As used herein, the term "single bond" refers to a bond that connects both atoms without any atom. For example, when [X] in the above formula 4 is [ka] where M is a single bond, the aromatic rings on both sides can be directly linked to each other to form a biphenyl structure.

[0047] In this specification, unless otherwise specified, the term "alkyl group" refers to 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. The alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituents include polar functional groups such as one or more substituents consisting of halogen, hydroxyl group, alkoxy group, thiol group, or thiol ether group.

[0048] Unless otherwise specified, the term "alkenyl group" used herein refers to an alkenyl 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 8 carbon atoms, or 2 to 4 carbon atoms. The alkenyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituents include polar functional groups such as one or more substituents consisting of halogen, hydroxyl group, alkoxy group, thiol group, or thiol ether group.

[0049] Unless otherwise specified, the term "alkynyl group" used herein refers to an alkynyl group having 2 to 30, 2 to 25, 2 to 20, 2 to 16, 2 to 12, 2 to 8, or 2 to 4 carbon atoms. The alkynyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituents include polar functional groups such as one or more substituents consisting of halogen, hydroxyl, alkoxy, thiol, or thiol ether groups.

[0050] In this specification, unless otherwise specified, the term "alkylene group" refers to 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. The alkylene group is a divalent organic group formed by removing two hydrogen atoms from different carbon atoms, and may have a linear, branched, or cyclic structure, and may be optionally substituted with one or more substituents. Examples of the substituents include polar functional groups such as one or more substituents consisting of halogen, hydroxyl group, alkoxy group, thiol group, or thiol ether group.

[0051] In this specification, unless otherwise specified, the term "alkylidene group" refers to 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. The alkylidene group is a divalent organic group formed by removing two hydrogen atoms from one carbon atom, and may have a linear, branched, or cyclic structure, and may be optionally substituted with one or more substituents. Examples of the substituents include polar functional groups such as one or more substituents consisting of halogen, hydroxyl group, alkoxy group, thiol group, or thiol ether group.

[0052] In this specification, unless otherwise specified, the term "alkoxy group" refers to 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. The alkoxy group may have a linear, branched, or cyclic alkyl group, and the alkyl group may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0053] In this specification, unless otherwise specified, the term "alkylamine group" includes monoalkylamine (-NHR) and dialkylamine (-NR2), where each R independently represents an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen atom, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0054] In this specification, unless otherwise specified, the term "alkylamide" includes monoalkylamide (-C(O)NHR) or dialkylamide (-C(O)NR), where each R independently represents an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched, or cyclic structure, and may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0055] As used herein, unless otherwise specified, the term "thiol ether group" or "sulfide" refers to -SR, where each R independently represents an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen atom, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0056] Unless otherwise specified, the term "sulfoxide" used herein refers to -S(O)R, where each R independently represents an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen atom, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0057] In this specification, unless otherwise specified, the term "carbonyl" includes -C(O)R, where each R independently represents an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched, or cyclic structure, and may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen atom, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0058] Unless otherwise specified, the term "ester" as used herein includes -C(O)OR or -OC(O)R, where each R independently represents an alkyl group having 1 to 30, 1 to 25, 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms. The alkyl group may have a linear, branched, or cyclic structure and may be optionally substituted with one or more substituents. Examples of the substituent include one or more substituents consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thiol ether group.

[0059] Aliphatic tetracarboxylic dianhydrides satisfying the chemical formula 4 include 1,2,4,5-cyclohexanetetracarboxylic dianhydride (or 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), bicyclo[2.2.2]oct-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-cycloalkanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (ChODA), cyclopentanonebisspironorbornanetetracarboxylic dianhydride (CpODA), bicyclo[2.2.1]heptane-2,3,5-tricarboxylic-5-acetic dianhydride (BSDA), dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride (DCDA), dicyclohexyl-2,3'3,4'-tetracarboxylic dianhydride (HBPDA), or 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride (DOCDA).

[0060] The aromatic tetracarboxylic dianhydride satisfying the chemical formula 4 includes pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or a-BPDA), oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (or DSDA), bis(3,4-dicarboxamide), bis(3,4-dicarboxylic acid ... 2,2-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 acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, Examples of the dianhydride include p-phenylene bis(trimellitic acid monoester anhydride), p-biphenylene bis(trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)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 dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride (6-FDA).

[0061] The compound represented by Chemical Formula 4 is preferably an aromatic tetracarboxylic dianhydride, particularly pyromellitic dianhydride (or PMDA), 9,10-difluoro-9,10-bis(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetracarboxylic dianhydride (6FDA), oxydiphthalic dianhydride (or ODPA), or 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA).

[0062] For example, the diamine monomer may include at least one compound represented by the following Formula 5: [ka] In Chemical Formula 5, any one of B1 to B5 is an amino group (-NH2), -R-NH2, or -OR-NH2, wherein R is a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, or a substituted or unsubstituted arylene group, and the others are hydrogen, halogen, a hydroxyl group, a carboxyl group, or an alkylene group substituted or unsubstituted with halogen.

[0063] The diamine monomers that can be used to prepare the polyamic acid solution are aromatic diamines, and examples thereof can be classified as follows: 1) Diamines with a relatively rigid structure, such as 1,4-diaminobenzene (or paraphenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, or 3,5-diaminobenzoic acid (or DABA), which have one benzene nucleus in their structure; 2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or 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'-diaminobiphenylmethane, 3,3'-dicarboxy-4,4'-diaminobiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminobiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or is 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, 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, Diamines having two benzene rings in their structure, such as 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, 2,2'-bistrifluoromethylbenzidine (TFMB), or 4,4'-diaminodiphenyl sulfoxide; 3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q), 1,4-bis(4-aminophenoxy)benzene (or 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, 1 Diamines having three benzene nuclei in their structure, such as 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, or 1,4-bis[2-(4-aminophenyl)isopropyl]benzene; 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-aminopenoxy)penyl] ether, bis[3-(4-aminopenoxy)penyl] ether, bis[4-(3-aminopenoxy)penyl] ether, bis[4-(4-aminopenoxy)penyl] ether, bis[3-(3-aminopenoxy)penyl] ketone, bis[3-(4-amino bis[4-(3-aminopenoxy)penyl]ketone, bis[4-(4-aminopenoxy)penyl]ketone, bis[4-(4-aminopenoxy)penyl]ketone, bis[3-(3-aminopenoxy)penyl]sulfide, bis[3-(4-aminopenoxy)penyl]sulfide, bis[4-(3-aminopenoxy)penyl]sulfide, bis[4-(4-aminopenoxy)penyl]sulfide, bis[3-(3-aminopenoxy)penyl]sulfone, bis[3-(4-aminopenoxy)penyl]sulfone, bis[4-(3-aminopenoxy)penyl] Sulfone, bis[4-(4-aminopenoxy)penyl]sulfone, bis[3-(3-aminopenoxy)penyl]methane, bis[3-(4-aminopenoxy)penyl]methane, bis[4-(3-aminopenoxy)penyl]methane, bis[4-(4-aminopenoxy)penyl]methane, 2,2-bis[3-(3-aminopenoxy)penyl]propane, 2,2-bis[3-(4-aminopenoxy)penyl]propane, 2,2-bis[4-(3-aminopenoxy)penyl]propane, 2,2-bis[4-(4-aminopenoxy)penyl] Diamines with four benzene rings in their structure, such as 2,2-bis[3-(3-aminopenoxy)penyl]-1,1,1,3,3,3-hexafluoropropane (BAPP), 2,2-bis[3-(4-aminopenoxy)penyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminopenoxy)penyl]-1,1,1,3,3,3-hexafluoropropane, or 2,2-bis[4-(4-aminopenoxy)penyl]-1,1,1,3,3,3-hexafluoropropane.

[0064] The diamine monomers can be used alone or in combination of two or more types, as needed. For example, the diamine monomers can be selected from the group consisting of 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,5-diaminobenzoic acid (or DABA), 2,2'-bistrifluoromethylbenzidine (TFMB), and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and can be used alone or in combination of two or more types.

[0065] In one example, the dianhydride monomer may be contained in a range of 90 to 100 mol% relative to 100 mol% of the diamine monomer, for example, 91 to 100 mol%, 92 to 100 mol%, 93 to 100 mol%, 94 to 100 mol%, 95 to 100 mol%, 96 to 100 mol%, 97 to 100 mol%, 98 to 100 mol%, 98.5 to 100 mol%, or 98.9 to 100 mol% relative to 100 mol% of the diamine monomer.

[0066] In one embodiment, the polyamic acid composition may contain 5 to 40 wt %, 10 to 30 wt %, or 15 to 20 wt % of solids based on the total weight of the polyamic acid composition. By adjusting the solids content of the polyamic acid composition, the present application can prevent an increase in viscosity and prevent an increase in manufacturing costs and process time that would otherwise be required to remove a large amount of solvent during the curing process.

[0067] The polyamic acid composition of the present application contains a high molecular weight polyamic acid and at the same time has low viscosity characteristics. The polyamic acid composition of the present application can be heated at a temperature of 23° C. and 1 s -1 The viscosity measured under the shear rate condition 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.

[0068] In one embodiment, the polyamic acid composition of the present application may have a viscosity in the range of 500 to 10,000 cp. The viscosity may be measured, for example, using a Haake MARS40 at a temperature of 23°C. By adjusting the viscosity range, the present application can provide a polyamic acid composition with excellent processability and easy product application.

[0069] The present application also relates to a polyimide precursor comprising a polymerized product of the aforementioned polyamic acid composition.

[0070] In one example, the polymer comprises a modified polyamic acid having polymerized units derived from a dianhydride monomer and a diamine monomer, and end-capped with an end-capping agent.

[0071] Specifically, the modified polyamic acid may include at least one of a first modified polyamic acid having polymerization units derived from a dianhydride monomer and a diamine monomer and having terminals capped with a first terminal capping agent; and a second modified polyamic acid having polymerization units derived from a dianhydride monomer and a diamine monomer and having terminals capped with a second terminal capping agent.

[0072] The modified polyamic acid is produced by reacting a polyamic acid with an end-capping agent at a temperature of 25 to 50°C for 1 to 5 hours, at a temperature of 25 to 50°C for 5 to 15 hours, or at a temperature of 25 to 30°C for 7 to 12 hours.

[0073] For example, the first modified polyamic acid is produced by reacting a polyamic acid with a first end-capping agent at a temperature of 25 to 50°C for 5 to 15 hours, or at a temperature of 25 to 30°C for 7 to 12 hours.

[0074] The second modified polyamic acid is produced by reacting a polyamic acid with a second end-capping agent at a temperature of 25 to 50° C. for 7 to 12 hours.

[0075] The explanation of each component is omitted below since it overlaps with the above content.

[0076] The present application also relates to a polyimide film including a cured product of a polyimide precursor. For example, the polyimide film may include a cured product of a modified polyamic acid. The polyimide film may include at least one of the cured products of the first modified polyamic acid and the second modified polyamic acid.

[0077] The polyimide film is produced by imidizing a polyimide precursor through thermal curing. The thermal curing conditions are not particularly limited, but may be within a temperature range of 100 to 400°C.

[0078] The polyimide film may be attached to the lower substrate of a display device, and thus the film may have a small thickness suitable for attachment to a product, for example, the thickness may be within the range of 1 to 100 μm, 5 to 90 μm, 5 to 80 μm, 5 to 70 μm, 10 to 100 μm, 10 to 90 μm, 10 to 80 μm, 10 to 70 μm, 10 to 60 μm, or 10 to 50 μm.

[0079] Furthermore, the polyimide film is manufactured by curing a modified polyamic acid, and therefore has excellent optical properties, surface properties, and mechanical properties.

[0080] Specifically, the polyimide film may have a 1% thermal decomposition temperature (td) measured using a TGA (Thermo Gravimetric Analysis) device within a range of 300 to 600° C., 350 to 600° C., or 400 to 600° C. The 1% thermal decomposition temperature (td) can be measured by removing moisture from the film at 150° C. using a TGA device and then heating the film to 600° C. at a heating rate of 10° C. / min.

[0081] In one specific example, the 1% thermal decomposition temperature (td) of the polyimide film containing the cured product of the first modified polyamic acid may be within a range of 150 to 600°C, 200 to 600°C, 250 to 600°C, 300 to 600°C, 350 to 600°C, or 400 to 600°C, and the 1% thermal decomposition temperature (td) of the polyimide film containing the cured product of the second modified polyamic acid may be within a range of 100 to 600°C, 200 to 600°C, 300 to 600°C, 400 to 600°C, 450 to 600°C, or 500 to 600°C.

[0082] In one example, the polyimide film may have a coefficient of thermal expansion (CTE) of 10.0 ppm / °C or less in the temperature range of 50 to 400°C. For example, the upper limit of the CTE may be 9.5 ppm / °C, 9 ppm / °C, 8.5 ppm / °C, 8 ppm / °C, 7.5 ppm / °C, 7 ppm / °C, 6.5 ppm / °C, 6 ppm / °C, 5.5 ppm / °C, 5 ppm / °C, 4.5 ppm / °C, 4 ppm / °C, 3.5 ppm / °C, 3 ppm / °C, 2.5 ppm / °C, or 2 ppm / °C or less. The coefficient of thermal expansion is measured at 100 to 460°C using a thermomechanical analyzer (TA Corporation) and may be measured in accordance with the ASTM E831 standard. Specifically, polyimide is manufactured into a film and cut into a width of 5 mm and a length of 16 mm. Then, under a nitrogen atmosphere, a tension of 0.02 N to 0.1 N, for example 0.02 N, is applied, and the temperature is raised from room temperature to 500°C at a rate of 10°C / min. Then, the film is cooled again at a rate of 10°C / min. After that, the temperature is raised at the same rate, and the gradient from 100°C to 460°C is measured.

[0083] In one specific example, the coefficient of thermal expansion (CTE) of a polyimide film containing a cured product of the first modified polyamic acid may be 10.0 ppm / °C or less in the temperature range of 50 to 400°C. For example, the coefficient of thermal expansion of the polyimide film may be 20.0 ppm / °C or less, 15.0 ppm / °C or less, 10.0 ppm / °C or less, 9.9 ppm / °C or less, 9.8 ppm / °C or less, or 9.5 ppm / °C or less in the temperature range of 100 to 460°C, and the lower limit may be, for example, -2 ppm / °C, -1 ppm / °C, -0.5 ppm / °C, or -0.1 ppm / °C or more. The coefficient of thermal expansion was measured at 100 to 460°C using a thermomechanical analyzer (TA Q450) in accordance with ASTM E831. Specifically, polyimide is manufactured into a film and cut into a width of 5 mm and a length of 16 mm. Then, under a nitrogen atmosphere, a tension of 0.02 N to 0.1 N, for example 0.02 N, is applied, and the temperature is raised from room temperature to 500°C at a rate of 10°C / min. Then, the film is cooled again at a rate of 10°C / min. After that, the temperature is raised at the same rate, and the gradient from 100°C to 460°C is measured.

[0084] In another example, the polyimide film containing the cured product of the second modified polyamic acid may have a coefficient of thermal expansion (CTE) in the range of 5 ppm / °C or less. For example, the upper limit of the CTE may be 4.5 ppm / °C, 4 ppm / °C, 3.5 ppm / °C, 3 ppm / °C, 2.5 ppm / °C, or 2 ppm / °C or less. The CTE may be measured at 100 to 460°C. The CTE can be measured using a TA Thermomechanical Analyzer (Model Q400) by heating a 10 μm thick, 5 mm wide, and 16 mm long polyimide film from room temperature to 500°C at a rate of 10°C / min under a tension of 0.02 N in a nitrogen atmosphere, and then cooling it again at a rate of 10°C / min to measure the slope from 100°C to 460°C.

[0085] In one example, the polyimide film may have an average light transmittance of 60% or more at a wavelength of 400 to 760 nm. For example, the average light transmittance may be 61% or more, 62% or more, 63% or more, 64% or more, 65% or more, 66% or more, 67% or more, 68% or more, 69% or more, 70% or more, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, or 78% or more. The upper limit is not particularly limited, but may be 99% or less, 95% or less, or 90% or less. The average light transmittance may be measured using a UV-Vis spectrophotometer, for example, a Hunter Lab Color-meter. A polyimide film satisfying the above average light transmittance may include a cured product of a second modified polyamic acid.

[0086] The present application also relates to a display device. For example, the device includes a substrate and the polyimide film attached to the lower surface of the substrate. The type of the display device is not particularly limited, and various types can be used without limitation. The display device has excellent heat resistance, light resistance, and electrical properties due to the polyimide film attached to the lower surface of the substrate.

[0087] The present application relates to a method for producing a polyimide precursor containing polyamic acid, which includes the steps of: polymerizing a dianhydride monomer and a diamine monomer in an organic solvent represented by the following Chemical Formula 1 to produce a polyamic acid; and reacting the produced polyamic acid with an end-capping agent having at least one functional group reactive with the end of the polyamic acid to produce a modified polyamic acid. [ka] In the above Chemical Formula 1, at least one of A1 to A3 is an alkylamine group, a hydroxy group, an alkoxy group, a thiol ether group, an alkyl group, or a heterocyclic group.

[0088] In one example, in the step of preparing the modified polyamic acid, the polymerization reaction may be carried out at a temperature of 25 to 50°C for 1 to 5 hours, at a temperature of 25 to 50°C for 5 to 15 hours, or at a temperature of 25 to 30°C for 7 to 12 hours.

[0089] In one specific example, the production method is a method for producing a polyimide precursor containing at least one of the first modified polyamic acid and the second modified polyamic acid.

[0090] For example, the method may include the steps of: preparing a polyamic acid by polymerizing a dianhydride monomer and a diamine monomer in an organic solvent represented by the following Chemical Formula 1; and preparing a first modified polyamic acid by reacting the prepared polyamic acid with a first end-capping agent, which is an anhydride-based agent having at least one functional group reactive with an end of the polyamic acid. [ka] In the above Chemical Formula 1, at least one of A1 to A3 is an alkylamine group, a hydroxy group, an alkoxy group, a thiol group, a thiol ether group, an alkyl group, or a heterocyclic group.

[0091] In one example, the polymerization reaction in the step of preparing the first modified polyamic acid may be carried out at a temperature ranging from 25 to 50° C. for 1 to 5 hours.

[0092] In another example, in the step of preparing the first modified polyamic acid, the polymerization reaction may be carried out at a temperature of 25 to 50° C. for 5 to 15 hours or at a temperature of 25 to 30° C. for 7 to 12 hours.

[0093] In another example, the method includes the steps of: preparing a polyamic acid by polymerizing a dianhydride monomer and a diamine monomer in an organic solvent represented by the following Chemical Formula 1; and preparing a second modified polyamic acid by reacting the prepared polyamic acid with a second end-capping agent, which is a diamine-based compound having at least one siloxane group and reactive with the end of the polyamic acid. [ka] In the above Chemical Formula 1, at least one of A1 to A3 is an alkylamine group, a hydroxy group, an alkoxy group, a thiol group, a thiol ether group, an alkyl group, or a heterocyclic group.

[0094] In another example, the step of preparing the second modified polyamic acid may be carried out at a temperature of 25 to 50° C. for 7 to 12 hours.

[0095] The explanation of each component is omitted below since it overlaps with the above content. [Effects of the Invention]

[0096] The present application provides a polyamic acid composition capable of realizing a polyimide film having environmentally friendly surface properties and durability, and capable of realizing a polyimide film having optical properties and durability equivalent to or superior to existing polyimide films produced using environmentally friendly organic solvents but using hazardous substances that are defined as hazardous substances; a polyimide precursor including a polymer of the polyamic acid composition; a polyimide film including a cured product of the polyimide precursor; and a method for producing the polyimide precursor. DETAILED DESCRIPTION OF THE INVENTION

[0097] The present application will be specifically described through the following examples, but the scope of the present application is not limited to the following examples.

[0098] Example 1A A 500 mL glass reaction vessel equipped with a stirrer, nitrogen gas inlet, and outlet was charged with N,N-dimethylpropionamide (DMPA) as an organic solvent, 100 mol% 1,4-diaminobenzene (PPD), and 95 mol% 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) at a ratio of 100 mol% to 1,4-diaminobenzene (PPD). Polymerization was carried out at 25°C to produce a polyamic acid solution with a solids concentration of 15%. Phthalic anhydride (PA) at a ratio of 10 mol% to 100 mol% 1,4-diaminobenzene was added to the polyamic acid solution to produce a polyamic acid composition. The polyamic acid composition was stirred for 2 hours to produce a polyimide precursor.

[0099] The polyimide precursor was then heat-cured from 100° C. to 460° C. at a temperature increase rate of 5° C. / min to prepare a polyimide film (the film thickness is shown in Table 2 below).

[0100] Examples 2A to 9A A polyimide precursor was prepared in the same manner as in Example 1A, except for the composition shown in Table 1 below.

[0101] Comparative examples 1A~2A A polyamic acid solution was prepared in the same manner as in Example 1A, except for the composition shown in Table 1 below.

[0102] [Table 1]

[0103] Example 1A - Surface Properties The surface properties of the polyimide films prepared in the Examples and Comparative Examples were evaluated according to the following criteria, and the results are shown in Table 2 below. O: No bubbles (excellent surface properties) △: Little bubble generation (normal surface characteristics) X: Many bubbles occur (poor surface properties)

[0104] Experimental Example 2A - 1% Thermal Decomposition Temperature (1% Td) The 1% thermal decomposition temperature of the polyimide films prepared in the Examples and Comparative Examples was measured using a TA thermogravimetric analyzer, Model Q50. The polyimide films were heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere and maintained at the same temperature for 30 minutes to remove moisture. The temperature was then increased to 600°C at a rate of 10°C / min, and the temperature at which a 1% weight loss occurred was measured. The results are shown in Table 2 below.

[0105] Example 3A - Coefficient of Thermal Expansion (CTE) The coefficient of thermal expansion (CTE) of the polyimide films prepared in the examples and comparative examples was measured at 100 to 460°C using a thermomechanical analyzer (TA Q450).

[0106] Specifically, the polyimide films prepared in the examples and comparative examples were cut into a width of 5 mm and a length of 16 mm. Then, under a nitrogen atmosphere, a tension of 0.02 N was applied and the temperature was raised from room temperature to 500°C at a rate of 10°C / min. Then, the film was cooled again at a rate of 10°C / min. The temperature was then raised at the same rate and the gradient in the range from 100°C to 460°C was measured. The results are shown in Table 2 below.

[0107] [Table 2]

[0108] Referring to Tables 1 and 2, in the case of Examples 1A to 9A, which used the environmentally friendly solvent DMPA and the first end-capping agent, the thermal expansion coefficient in the range of 100 to 460°C was 3.4 ppm / °C or less, and the 1% thermal decomposition temperature was 555°C or more. Therefore, it was confirmed that the durability was similar to that of Comparative Example 1A, which used NMP, which is defined as a hazardous substance, as the organic solvent, and the appearance (surface properties) was also excellent.

[0109] On the other hand, in the case of Comparative Example 2A, in which DMPA was used but no first end-capping agent was used, the thermal expansion coefficient in the range of 100 to 460°C was 3.6 ppm / °C, and the 1% thermal decomposition temperature was 541°C, indicating poor durability and poor appearance.

[0110] Example 1B N,N-dimethylpropionamide (DMPA) was added as an organic solvent to a 500 mL glass reaction vessel equipped with a stirrer, nitrogen gas inlet, and outlet. 100 mol% of 1,4-diaminobenzene (PPD) and 99.9 mol% of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were then added. The mixture was polymerized at 25°C for 2 hours to produce a polyamic acid solution with a solids concentration of 15%. 1,3-Bis(3-aminopropyl)tetramethyldisiloxane (SIDA) was added to the polyamic acid solution to produce a polyamic acid composition. The SIDA was added at 0.1 wt% based on the total polyamic acid composition. The polyamic acid composition was reacted at 25°C for 7 hours to produce a polyimide precursor.

[0111] The polyimide precursor was then heat-cured from 100° C. to 460° C. at a temperature increase rate of 5° C. / min to prepare a polyimide film (the film thickness is shown in Table 4 below).

[0112] Examples 2B to 6B Polyimide precursors and cured polyimide films were prepared in the same manner as in Example 1B, except for the compositions shown in Table 3 below.

[0113] Comparative Examples 1B and 2B Polyimide precursors and cured polyimide films were prepared in the same manner as in Example 1B, except for the compositions shown in Table 3 below.

[0114] [Table 3]

[0115] Experimental Example 1B - 1% Thermal Decomposition Temperature (1% Td) The 1% thermal decomposition temperature of the polyimide films prepared in the Examples and Comparative Examples was measured using a TA thermogravimetric analyzer, Model Q50. The polyimide films were heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere and then maintained at the same temperature for 30 minutes to remove moisture. The temperature was then increased to 600°C at a rate of 10°C / min to measure the temperature at which a 1% weight loss occurred. The results are shown in Table 4 below.

[0116] Example 2B - Average Light Transmission The average light transmittance of the polyimide films prepared in the examples and comparative examples was measured at wavelengths of 400 to 760 nm using a Hunter Lab Color-meter, and the results are shown in Table 4 below.

[0117] Example 3B - Coefficient of Thermal Expansion (CTE) To measure the CTE, first, samples of 10 μm thick, 5 mm wide, and 16 mm long were prepared from the polyimide films prepared in the examples and comparative examples. Using a TA thermomechanical analyzer (model Q400), the prepared samples were heated from room temperature to 500°C at a rate of 10°C / min while applying a tension of 0.02 N under a nitrogen atmosphere, and then cooled again at a rate of 10°C / min, while measuring the slope in the 100°C to 460°C range. The results are shown in Table 4 below.

[0118] [Table 4]

[0119] Referring to Tables 3 and 4, in the case of Examples 1B to 6B, which used the environmentally friendly solvent DMPA and the second end-capping agent, the average light transmittance was 70% or more at a wavelength of 400 to 760 nm, the thermal expansion coefficient was 3.6 ppm / °C or less in the range of 100 to 460°C, and the 1% thermal decomposition temperature was 564°C or more. Therefore, it was found that the optical properties and durability were equivalent to those of Comparative Example 1B, which used NMP, which is defined as a hazardous substance, as the organic solvent.

[0120] On the other hand, in Comparative Example 2B, which used DMPA but did not use a second end-capping agent, the 1% thermal decomposition temperature was lower and the CTE value was higher than in the Examples. This confirmed that the use of a second end-capping agent helps improve durability when using DMPA.

[0121] The present invention described above is not limited to the above-described embodiments, as various substitutions and modifications may be made by a person having ordinary skill in the art to which the present invention pertains without departing from the technical spirit of the present invention.

Claims

1. a polyamic acid having polymerized units derived from a dianhydride monomer and a diamine monomer; An organic solvent containing a compound represented by the following chemical formula 1: A polyamic acid composition comprising an end-capping agent having at least one functional group reactive with an end of a polyamic acid: 【Chemistry 1】 In the above Chemical Formula 1, A 1 ~A 3 At least one of the groups is an alkylamine group, a hydroxy group, an alkoxy group, a thiol group, a thiol ether group, an alkyl group, or a heterocyclic group.

2. 2. The polyamic acid composition according to claim 1, wherein the end-capping agent comprises at least one selected from the group consisting of a first end-capping agent which is an anhydride-based compound and a second end-capping agent which is a diamine-based compound having at least one siloxane group.

3. 2. The polyamic acid composition according to claim 1, wherein the compound represented by Chemical Formula 1 is N,N-dimethylpropionamide (DMPA).

4. 3. The polyamic acid composition according to claim 2, wherein the first end-capping agent comprises an anhydride compound having an aliphatic ring group, a heterocyclic group, or an aromatic ring group.

5. 5. The polyamic acid composition according to claim 4, wherein the anhydride compound contains one or more functional groups selected from the group consisting of a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a hydroxy group, a carboxyl group, an isocyanate group, and a cyanate group.

6. 2. The polyamic acid composition according to claim 1, wherein the content of the end-capping agent is in the range of 0.01 to 20 mol % relative to 100 mol % of the diamine monomer.

7. The polyamic acid composition according to claim 2, wherein the second end-capping agent is a diamine compound having a silsesquioxane structure represented by the following Chemical Formula 2 or Chemical Formula 3: 【Chemistry 2】 [Chemical formula 3] [R 7 SiO 3 / 2 ] m In the above Chemical Formula 2, n is an integer from 1 to 10, R 1 ~R 4 are each independently an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, R 5 and R 6 each independently represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a substituted or unsubstituted arylene group, -O-, -S-, -C(=O)-, or -S(=O) 2 - is a linking group containing one or more divalent substituents selected from the group consisting of In the above Chemical Formula 3, m is an integer from 6 to 15; R 7 At least two of the groups are amine groups, and the rest are organic groups having 1 to 20 carbon atoms or halogen groups.

8. 2. The polyamic acid composition of claim 1, wherein the dianhydride monomer comprises at least one compound represented by the following formula 4: 【Transformation 3】 In the above Chemical Formula 4, [X] represents a tetravalent aliphatic cyclic group, a tetravalent aromatic cyclic group, or a tetravalent heterocyclic group, The aliphatic cyclic group, the aromatic cyclic group, or the heterocyclic group is Is it a single ring? is a fused ring; or A single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a substituted or unsubstituted arylene group, -O-, -S-, -C(=O)- or -S(=O) 2 - and -Si(R b ) 2 -, wherein R b is hydrogen or an alkyl group.

9. The [X] is 【Chemistry 4】 、 【Transformation 5】 、 or an aliphatic cyclic group, The M is a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O) 2 9. The polyamic acid composition according to claim 8, comprising at least one selected from the group consisting of -.

10. 2. The polyamic acid composition according to claim 1, wherein the diamine monomer comprises at least one compound represented by the following formula 5: 【Transformation 6】 In the above-mentioned Chemical Formula 5, B 1 ~B 5 One of the amino groups (-NH 2 ), -R-NH 2 , or -OR-NH 2 wherein R is a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, or a substituted or unsubstituted arylene group, and the others are hydrogen, halogen, a hydroxyl group, a carboxyl group, or an alkylene group substituted or unsubstituted with a halogen.

11. A polyimide precursor comprising a polymer of the polyamic acid composition according to claim 1.

12. 12. The polyimide precursor according to claim 11, wherein the polymer comprises a modified polyamic acid having polymerized units derived from a dianhydride monomer and a diamine monomer and whose ends are capped with an end-capping agent.

13. A polyimide film comprising a cured product of the polyimide precursor according to claim 11.

14. 14. The polyimide film according to claim 13, wherein the 1% thermal decomposition temperature (td) is in the range of 300 to 600°C.

15. 14. The polyimide film according to claim 13, having a coefficient of thermal expansion (CTE) of 10.0 ppm / °C or less in the range of 100 to 460°C.

16. 14. The polyimide film according to claim 13, having an average light transmittance of 60% or more at wavelengths of 400 to 760 nm.

17. preparing a polyamic acid by polymerizing a dianhydride monomer and a diamine monomer in an organic solvent represented by the following formula 1: A method for producing a polyimide precursor, comprising the step of reacting the produced polyamic acid with an end-capping agent having at least one functional group reactive with an end of the polyamic acid to produce a modified polyamic acid: 【Transformation 7】 In the above Chemical Formula 1, A 1 ~A 3 At least one of the groups is an alkylamine group, a hydroxy group, an alkoxy group, a thiol group, a thiol ether group, an alkyl group, or a heterocyclic group.

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