Polyamic acid composition

Abstract

The present application provides a polyamic acid composition capable of simultaneously realizing excellent storage stability, low dielectric constant, heat resistance, insulation, and mechanical properties under harsh conditions such as high temperature, a polyimide which is a cured product of the composition, a coating comprising the polyimide, and an electronic device comprising the coating.

Description

Technology Field

[0001] The present application relates to a polyamic acid composition, a polyimide which is a cured product of the composition, a coating comprising the polyimide, and an electronic device comprising the coating. Background Technology

[0002] The insulating layer (insulating coating) covering the conductor is required to have excellent insulation properties, adhesion to the conductor, heat resistance, or mechanical strength.

[0003] In addition, in electrical equipment with high applied voltage, such as motors used at high voltage, high voltage is applied to the insulated wires constituting the electrical equipment, and partial discharge (corona discharge) is likely to occur on the surface of the insulating sheath.

[0004] The occurrence of corona discharge can cause a localized temperature rise or the generation of ozone or ions, which results in the deterioration of the insulation sheathing of insulated wires, leading to premature insulation breakdown and shortening the lifespan of electrical equipment.

[0005] For insulated wires used at high voltages, an improvement in the corona discharge initiation voltage is required for the reasons mentioned above, and it is known that lowering the dielectric constant of the insulation layer is effective for this purpose.

[0006] Examples of resins that can be used in the insulating layer include polyimide resin, polyamideimide resin, or polyesterimide resin.

[0007] Among these, polyimide resin, in particular, is a material with excellent heat resistance and insulation properties, making it suitable for use as a coating material for conductors.

[0008] Polyimide resin refers to a high-heat-resistant resin produced by solution polymerizing an aromatic dianhydride with an aromatic diamine or aromatic diisocyanate to produce a polyamic acid derivative, and then performing ring-closing dehydration at high temperatures to produce an imid.

[0009] As a method for forming an insulating sheath using such a polyimide resin, for example, a method may be used in which a polyimide varnish, which is a precursor of the polyimide resin, is applied or coated around a wire made of a conductor, and then the polyimide varnish is imidized in a curing furnace capable of heat treatment at a predetermined temperature.

[0010] However, despite their excellent physical properties, general polyimide resins have poor storage stability and do not have excellent adhesion to conductors; therefore, when forming an insulating coating, problems such as appearance defects may occur due to delamination between the conductor and the coating.

[0011] Therefore, there is a need to produce polyimide varnish for conductor coatings that simultaneously satisfies storage stability, heat resistance, insulation, low dielectric constant, adhesion, and mechanical properties. The problem to be solved

[0012] The present application provides a polyamic acid composition capable of simultaneously realizing excellent storage stability, low dielectric constant, heat resistance, insulation, and mechanical properties under harsh conditions such as high temperature, a polyimide which is a cured product of the composition, a coating comprising the polyimide, and an electronic device comprising the coating. means of solving the problem

[0013] The present application relates to a polyamic acid composition. The polyamic acid composition according to the present invention may be a polyimide varnish capable of providing a polyimide that can simultaneously satisfy flexibility, light resistance, heat resistance, insulation, adhesion, and mechanical properties at high temperatures after curing.

[0014] The above polyamic acid composition comprises diamine monomers and dianhydride monomers as polymerization units, and the viscosity change rate at 23°C (△V) of the following general formula 1. 23℃ ) satisfies -25% to +25%.

[0015] [General Formula 1]

[0016] △V23℃ = (V2 - V1) / V1 × 100

[0017] In the above general formula 1, △V 23℃ This represents the rate of change of the viscosity (V2) of the polyamic acid composition stored for one week in a sealed storage container at a temperature of 23°C, based on the viscosity (V1) of the polyamic acid composition before storage.

[0018] For example, the above 23℃ viscosity change rate (△V 23℃ ) may satisfy -25% to +25%, -22% to +22%, -20% to +20%, -19% to +19%, -18% to +18%, -16% to +16%, -14% to +14%, -12% to +12%, or -10% to +10%. The viscosity (V1, V2) of the above general formula 1 may be measured using a Haake Rheostress 600 and may be measured under conditions of a shear rate of 1 / s, a temperature of 30°C, and a 1 mm plate gap. The above storage container may be made of various known materials without limitation, for example, an aluminum can or a bottle made of PP material may be used.

[0019] The polyamic acid composition according to the present application satisfies the above general formula 1, and thus has excellent storage stability at 23°C.

[0020] The polyamic acid composition according to the present application has a viscosity change rate (△V) at 30°C of the following general formula 2. 30℃ This can satisfy -30% to +30%.

[0021] [General Formula 2]

[0022] △V 30℃ = (V4 - V3) / V3 × 100

[0023] In the above general formula 2, △V 30℃This represents the rate of change of the viscosity (V4) of the polyamic acid composition stored for one week in a sealed storage container at a temperature of 30°C, based on the viscosity (V3) of the polyamic acid composition before storage.

[0024] For example, the above 30℃ viscosity change rate (△V 30℃ ) can satisfy -30% to +30%, -25% to +25%, -22% to +22%, -20% to +20%, -19% to +19%, -18% to +18%, -16% to +16%, -14% to +14%, -12% to +12%, or -10% to +10%.

[0025] The polyamic acid composition according to the present application satisfies the above general formula 2, and thus has excellent storage stability at 30°C.

[0026] The viscosity (V3, V4) of the above general formula 2 may be measured using Haake’s Rheostress 600 and may be measured under conditions of a shear rate of 1 / s, a temperature of 30°C, and a plate gap of 1 mm.

[0027] The polyamic acid composition according to the present application may further comprise a modified monomer represented by the following chemical formula 1.

[0028] [Chemical Formula 1]

[0029]

[0030] In the above Chemical Formula 1, A1 to A4 are each independently a hydroxyl group (-OH), an amine group (-NH2), an alkoxy group, or an oxygen anion (-O - Selected as one of ),

[0031] In the above chemical formula 1, X is a tetravalent aliphatic ring, a tetravalent heteroaliphatic ring, a tetravalent aromatic ring, or a tetravalent heteroaromatic ring, and the carbon atom of the carbonyl group of chemical formula 1 is connected to a ring constituent atom of the aliphatic ring, heteroaliphatic ring, aromatic ring, or heteroaromatic ring, and

[0032] The above aliphatic ring, the above heteroaliphatic ring, the above aromatic ring, or the above heteroaromatic ring is

[0033] It is a single ring, or

[0034] They are joined together to form a polycyclic ring; or

[0035] It is connected by a linker comprising 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)-, -S(=O)2- and -Si(Rb)2-, where Rb is hydrogen or an alkyl group.

[0036] Preferably, X of Formula 1 is phenyl, biphenyl, Or it is an aliphatic ring,

[0037] The above M includes at least one from the group comprising a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O)2-.

[0038] The modified monomer represented by Chemical Formula 1 above may be derived from a dianhydride monomer, which is a polymerization unit of polyamic acid. As the molar amount of the modified monomer increases, the elongation of the cured polyimide tends to decrease. When coating a conductor, the elongation of the conductor coating winding can be induced to match the elongation of the conductor coating winding by controlling the molar amount of the modified monomer, and accordingly, the lifting phenomenon between the winding and the coating can be suppressed.

[0039] In one example, the modified monomer represented by the above chemical formula 1 may be included in a range of 6 to 15 mol% with respect to 100 mol% of the diamine monomer of the polyamic acid. The above modified monomer may be included in a range of 6 to 14 mol%, 6 to 13 mol%, 6 to 12 mol%, 6 to 11 mol%, 6 to 10 mol%, 6.5 to 15 mol%, 6.5 to 14 mol%, 6.5 to 13 mol%, 6.5 to 12 mol%, 6.5 to 11 mol%, 6.5 to 10 mol%, 7 to 15 mol%, 7 to 14 mol%, 7 to 13 mol%, 7 to 12 mol%, 7 to 11 mol%, or 7 to 10 mol% with respect to 100 mol% of the diamine monomer of the polyamic acid. By adjusting the molar ratio of the modified monomer within the above range, excellent storage stability, improved elongation upon curing, and excellent thermal stability, electrical properties, and mechanical stability can be achieved.

[0040] In another example, the molar ratio (A:B) of the dianhydride monomer (A) and the modified monomer (B) of the polyamic acid may be within the range of 1:0.06 to 1:0.15, within the range of 1:0.06 to 1:0.14, within the range of 1:0.06 to 1:0.13, within the range of 1:0.06 to 1:0.12, within the range of 1:0.06 to 1:0.11, within the range of 1:0.06 to 1:0.1, within the range of 1:0.07 to 1:0.14, within the range of 1:0.07 to 1:0.13, within the range of 1:0.07 to 1:0.12, within the range of 1:0.07 to 1:0.11, or within the range of 1:0.07 to 1:0.1.

[0041] In one embodiment, the dianhydride monomer, which is a polymerization unit of polyamic acid, comprises at least one compound represented by the following chemical formula 2.

[0042] [Chemical Formula 2]

[0043]

[0044] In the above chemical formula 2, Y is a tetravalent aliphatic ring, a tetravalent heteroaliphatic ring, a tetravalent aromatic ring, or a tetravalent heteroaromatic ring, and the carbon atom of the carbonyl group of chemical formula 2 is connected to a ring constituent atom of the aliphatic ring, heteroaliphatic ring, aromatic ring, or heteroaromatic ring, and

[0045] The above aliphatic ring, the above heteroaliphatic ring, the above aromatic ring, or the above heteroaromatic ring is

[0046] It is a single ring or;

[0047] They are joined together to form a polycyclic ring; or

[0048] 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 Connected by a linker comprising one or more divalent substituents selected from the group consisting of )2-, where R a is hydrogen or an alkyl group.

[0049] Preferably, Y of Formula 2 is phenyl, biphenyl, Or it is an aliphatic ring,

[0050] The above M includes at least one from the group comprising a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O)2-.

[0051] In this specification, the term “aliphatic ring group” may mean an aliphatic ring group having 3 to 30 carbon atoms, 4 to 25 carbon atoms, 5 to 20 carbon atoms, or 6 to 16 carbon atoms, unless specifically otherwise defined. Specific examples of tetravalent aliphatic ring groups include, for example, a group obtained by removing 4 hydrogen atoms 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, a cyclododecane ring, or a dicyclopentane ring.

[0052] In this specification, the term “aromatic ring group” may mean 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, unless specifically otherwise defined. The aromatic ring may be a monocyclic ring or a condensed ring. Examples of tetravalent aromatic hydrocarbon ring groups include, for instance, a benzene ring, a naphthalene ring, anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, or a pyrene ring from which 4 hydrogen atoms have been removed.

[0053] In this specification, the term “arylene group” may mean a divalent organic group derived from the aromatic ring group.

[0054] In this specification, the term “hetero-ring” includes hetero-aliphatic rings and hetero-aromatic rings.

[0055] In this specification, the term “hetero-aliphatic ring” may mean a ring in which at least one of the carbon atoms of the aliphatic ring is replaced by one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus.

[0056] In this specification, the term “hetero-aromatic ring” may mean a ring in which at least one of the carbon atoms of said aromatic ring is replaced by one or more heteroatoms selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus, unless specifically otherwise defined. The hetero-aromatic ring may be a monocyclic ring or a condensed ring.

[0057] The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group may each be independently substituted with one or more substituents selected from the group consisting of a halogen, a hydroxyl group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms that is substituted with or unsubstituted with a halogen, and an alkoxy group having 1 to 4 carbon atoms.

[0058] In this specification, the term “single bond” may mean a bond connecting two atoms without any atoms. For example, X of Formula 1 or Y of Formula 2 And, where M is a single bond, both aromatic rings can be directly connected to each other.

[0059] In this specification, the term “alkyl group” may mean 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 specifically defined otherwise. The alkyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include polar functional groups such as one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0060] In this specification, the term “alkenyl group” may mean 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 specifically otherwise defined. The alkenyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include polar functional groups, such as one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0061] In this specification, the term “alkynyl group” may mean 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 specifically otherwise defined. The alkynyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include polar functional groups, such as one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0062] In this specification, the term “alkylene group” may mean 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 specifically defined otherwise. The alkylene group is a divalent organic group in which two hydrogen atoms are removed from different carbon atoms and may have a straight-chain, branched-chain, or cyclic structure, and may optionally be substituted by one or more substituents. Examples of such substituents may include polar functional groups such as one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0063] In this specification, the term “alkylidene group” may mean 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 specifically otherwise defined. The alkylidene group is a divalent organic group in which two hydrogen atoms are removed from one carbon atom and may have a straight-chain, branched-chain, or cyclic structure, and may optionally be substituted by one or more substituents. Examples of such substituents may include polar functional groups such as one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0064] In this specification, the term “alkoxy group” may mean 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 specifically otherwise defined. The alkoxy group may have a straight-chain, branched-chain, or cyclic alkyl group structure, and the alkyl group may optionally be substituted by one or more substituents. Examples of the substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0065] In this specification, the term “alkylamine group” comprises monoalkylamine (-NHR) or dialkylamine (-NR2) unless specifically otherwise defined, wherein R may independently represent 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. Herein, the alkyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0066] In this specification, the term “alkylamide” comprises a monoalkylamide (-C(O)NHR) or a dialkylamide (-C(O)NR2) unless specifically otherwise defined, wherein R may independently represent 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 straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0067] In this specification, the terms “thiol ether group” or “sulfide” mean -SR unless specifically otherwise defined, wherein R may each independently mean 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. Herein, the alkyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0068] In this specification, the term “sulfoxide” means -S(O)R unless specifically otherwise defined, wherein R may independently mean 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 straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0069] In this specification, the term “carbonyl” comprises -C(O)R unless specifically otherwise defined, wherein R may independently represent 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. Herein, the alkyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0070] In this specification, the term “ester” comprises -C(O)OR or -OC(O)R unless specifically otherwise defined, wherein R may independently represent 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. Herein, the alkyl group may have a straight-chain, branched-chain, or cyclic structure and may optionally be substituted by one or more substituents. Examples of such substituents may include one or more substituents consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thiol ether group.

[0071] The aliphatic tetracarboxylic dianhydrides satisfying Chemical Formula 2 above are 1,2,4,5-cyclohexane tetracarboxylic dianhydride (or HPMDA), bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BODA), 1,2,3,4-cyclohexane tetracarboxylic dianhydride (CHMDA), bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BHDA), butane-l,2,3,4-tetracarboxylic dianhydride (BTD), and bicyclo-[2.2.2]oct-7-en-2-exo,3-exo,5-exo,6-exo-2,3:5,6-dianhydride (BTA). 1,2,3,4-cyclobutane tetracarboxylic dianhydride (CBDA), bicyclo[4.2.0]octane-3,4,7,8-tetracarboxylic dianhydride (OTD), norbonan-2-spiro-α-cyclohexanone-α'-spiro-2"-norbonan-5,5",6,6"-tetracarboxylic dianhydride (ChODA), cyclopentanone bis-spironorbonan tetracarboxylic dianhydride (CpODA), bicyclo[2.2.1]Heptane-2,3,5-tricarboxyl-5-acetic dianhydride (BSDA), dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride (DCDA), dicyclohexyl-2,3'3,4'-tetracarboxylic dianhydride (HBPDA), 5,5'-Oxybis(hexahydro-1,3-isobenzofurandion) (HODPA), 5,5'-Methylenebis(hexahydro-1,3-isobenzofurandion) (HMDPA), 3,3'-(1,4-piperazinediyl)bis[dihydro-2,5-furandion] (PDSA), 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexane-1,2-dicarboxylic anhydride (DOCDA), 3,4-Dicarboxy-1,2,3,4-Tetrahydro-1-Naphthalene Succinic Dianhydride (TDA), 3,4-Dicarboxy-1,2,3,4-Tetrahydro-6-Methyl-1-Naphthalene Succinic Dianhydride (MTDA), 3,4-Dicarboxy-1,2,3,4-Tetrahydro-6-Fluoro-1-Naphthalene Succinic Dianhydride (FTDA), 3,3,3',3'-Tetramethyl-1,1'-Spirobisindane-5,5',6,6'-Tetracarboxylic Anhydride (SBIDA), 4,4,4',4'-Tetramethyl-3,3',4,4'-Tetrahydro-2,2'-Spirobi[Furo[3,4-g]chromene]-6,6',8,8'-Tetraone (SBCDA), Examples include 9,10-difluoro-9,10-bis(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetracarboxylic acid dianhydride (6FDA).

[0072] The aromatic tetracarboxylic dianhydrides satisfying Chemical Formula 2 above are pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or α-BPDA), oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (or 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, and 3,3',4,4'-benzophenonetetracarboxylic Dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimelytic monoester acid anhydride), p-biphenylenebis(trimelytic monoester acid 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-dicarboxy Examples include phenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride (6-FDA).

[0073] In one embodiment, the dianhydride monomer may preferably be one or more selected from aromatic tetracarboxylic dianhydrides, for example, PDMA, BPDA, α-BPDA, ODPA, DSDA, or BTDA.

[0074] In one embodiment, the diamine monomer may include at least one compound represented by the following chemical formula 3.

[0075] [Chemical Formula 3]

[0076]

[0077] In the above chemical formula 3, any one of B1 to B5 is an amino group, and the remainder represents hydrogen; a halogen; a hydroxyl group; a carboxyl group; or an alkyl group substituted with or unsubstituted with a halogen.

[0078] As one example, the above diamine monomer is an aromatic diamine, and can be classified as follows.

[0079] 1) A diamine having one benzene nucleus in its structure, such as 1,4-diaminobenzene (or paraphenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (or DABA), etc., a diamine having a relatively rigid structure;

[0080] 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'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-Dimethylbenzidine (or o-tolidine), 2,2'-Dimethylbenzidine (or 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'-Diaminodiphenylsulfone, 3,4'-Diaminodiphenylsulfone, 4,4'-Diaminodiphenylsulfone, 3,3'-Diaminobenzophenone, 4,4'-Diaminobenzophenone, 3,3'-Diamino-4,4'-Dichlorobenzophenone, Diamines having two benzene nuclei in their structure, such as 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, 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'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide, etc.;

[0081] 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, 1,3-Bis(3-aminophenylsulfide)benzene, 1,3-Bis(4-aminophenylsulfide)benzene, A diamine having three benzene nuclei in its structure, such as 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, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, etc.;

[0082] 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)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]sulfide, Bis[3-(3-aminophenoxy)phenyl]sulfone, Bis[3-(4-aminophenoxy)phenyl]sulfone, Bis[4-(3-aminophenoxy)phenyl]sulfone, Bis[4-(4-aminophenoxy)phenyl]sulfone, Bis[3-(3-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, A diamine having four benzene nuclei in its structure, such as 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-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, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, etc.

[0083] The above diamine monomers may be used alone or in combination of two or more types as needed, and the present application may use two or more diamine monomers having different structural characteristics in consideration of bond dissociation energy, for example, a diamine having one benzene nucleus in its structure and a diamine having two or more benzene nuclei in its structure in combination.

[0084] In one embodiment, the diamine monomer may comprise at least two of 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, and 4,4'-methylenediamine (MDA), and, for example, may comprise 1,4-diaminobenzene (PPD) and 4,4'-diaminodiphenyl ether (or oxydianiline, ODA).

[0085] In one specific example, the polyamic acid composition may have a solid content of 5 to 40 weight%, 5 to 35 weight%, 10 to 40 weight%, 10 to 35 weight%, 10 to 30 weight%, 15 to 40 weight%, or 15 to 35 weight% based on the total weight, and preferably may contain 15 to 30 weight%. By controlling the solid content of the polyamic acid composition, the present application can prevent increased manufacturing costs and process time that require removing a large amount of solvent during the curing process while controlling the increase in viscosity.

[0086] In one embodiment, the polyamic acid of the present application may have a weight-average molecular weight in the range of 10,000 to 100,000 g / mol, 15,000 to 80,000 g / mol, 18,000 to 70,000 g / mol, 20,000 to 60,000 g / mol, 25,000 to 55,000 g / mol, or 30,000 to 50,000 g / mol. In the present application, the term weight-average molecular weight refers to a converted value for standard polystyrene measured by a Gel Permeation Chromatograph (GPC).

[0087] The present application may have a polyamic acid content in the range of 1 to 50 wt%, 1 to 45 wt%, 1 to 40 wt%, 1 to 30 wt%, 5 to 50 wt%, 5 to 45 wt%, 5 to 40 wt%, 5 to 30 wt%, 5 to 25 wt%, 5 to 20 wt%, 10 to 20 wt%, or 15 to 20 wt% based on the total amount of solids.

[0088] The polyamic acid composition of the present application may have low viscosity characteristics. The polyamic acid composition of the present application is at a temperature of 23°C and 1s -1 The viscosity measured under shear rate conditions may be 50,000 cP, 40,000 cP, 30,000 cP, 20,000 cP, 10,000 cP or less, and 9,000 cP or less. The lower limit is not specifically limited, but may be 500 cP or more or 1,000 cP or more. Preferably, the viscosity may be in the range of 1,000 to 30,000 cP. The viscosity may be measured, for example, using a Haake Rheostress 600 and under conditions of a shear rate of 1 / s, a temperature of 23°C, and a plate gap of 1 mm. By controlling the viscosity range, the present application can provide a polyamic acid composition with excellent processability and ease of product application.

[0089] The present application states that the polyamic acid composition may include an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent in which the polyamic acid can be dissolved, but as one example, it may be an aprotic polar solvent.

[0090] The above-mentioned aprotic polar solvents may include, for example, amide solvents such as N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc) or dimethylpropanamide (DMPA), phenol solvents such as p-chlorophenol or o-chlorophenol, N-methylpyrrolidone (NMP), gamma butyrolactone (GBL) or Diglyme, and these may be used alone or in combination of two or more.

[0091] In some cases, the solubility of the polyamic acid may be controlled by using an auxiliary solvent such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, or water.

[0092] In one example, the organic solvent may be, for example, N-methyl-pyrrolidone (NMP).

[0093] The above polyamic acid can be formed by polymerizing a diamine monomer and a dianhydride monomer in an inert atmosphere and within a temperature range of 20 to 60°C.

[0095] The present application also relates to a polyimide which is a cured product of the aforementioned polyamic acid composition. As the polyimide is cured from the aforementioned polyamic acid composition, it can simultaneously satisfy flexibility, light resistance, heat resistance, insulation, adhesion, and mechanical properties at high temperatures.

[0096] The above polyimide can be formed by thermal curing of polyamic acid. The thermal curing can be performed, for example, within a temperature range of 100 to 600°C.

[0097] The above polyimide can be controlled to have various physical properties within the following numerical ranges by adjusting the material and content ratio of the aforementioned polyamic acid composition.

[0098] The following physical properties may have been measured after preparing a sample of polyimide in the form of a film having a thickness of 10 to 30 μm.

[0099] For example, the elongation of the above polyimide measured using a Universal Testing Machine (UTM) device may be in the range of 10 to 60%. For example, the upper limit of the elongation may be 58% or less, 55% or less, 53% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, or 25% or less, and the lower limit of the elongation may be 10% or more, 12% or more, 15% or more, 18% or more, or 20% or more.

[0100] The above polyimide may have a tensile strength of 500 MPa or less as measured using a Universal Testing Machine (UTM) device, for example, 450 MPa or less, 400 MPa or less, 350 MPa or less, 300 MPa or less, 250 MPa or less, 200 MPa or less, 195 MPa or less, 190 MPa or less, or 150 MPa or less, and the modulus may be 15 GPa or less, 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 above measurement may be performed using a UTM device under conditions of a width of 20 mm, a grip distance of 50 mm, and a crosshead speed of 20 min / min.

[0101] In addition, the coefficient of thermal expansion (CTE) of the polyimide measured using a Thermo Mechanical Analysis (TMA) device may be within the range of 0.1 ppm / ℃ to 50 ppm / ℃, 0.5 ppm / ℃ to 50 ppm / ℃, 1 ppm / ℃ to 50 ppm / ℃, 5 ppm / ℃ to 50 ppm / ℃, 10 ppm / ℃ to 45 ppm / ℃, 15 ppm / ℃ to 40 ppm / ℃, 20 ppm / ℃ to 40 ppm / ℃, 25 ppm / ℃ to 40 ppm / ℃, or 25 ppm / ℃ to 35 ppm / ℃. The measurement may be performed using a TMA device while applying a load of 0.02 N at a temperature range of 50 to 200℃ at a heating rate of 10℃ / min.

[0102] The glass transition temperature of the above polyimide, measured using a Dynamic Mechanical Analysis (DMA) device, may be within the range of 200 to 500°C, 250 to 450°C, 300 to 400°C, or 350 to 400°C. The above measurement may be performed using a DMA device at a heating rate of 5°C / min.

[0103] In addition, the 5% thermal decomposition temperature of the above polyimide, measured using a TGA (Thermo Gravimetric Analysis) device, may be within the range of 450 to 650°C, 450 to 600°C, or 450 to 580°C. The measurement may be performed by preheating to a temperature of 150°C and using a TGA device at a heating rate of 10°C / min for 30 minutes.

[0104] In addition, the above polyimide may have a dielectric constant (Dk) measured according to ASTM D150 in the range of 1 to 5, 1 to 4.5, 1.5 to 4.5, 2 to 4, 2.5 to 4, 3 to 4, or 3.2 to 4.

[0105] The above polyimide may have a dielectric breakdown voltage (BDV) measured according to ASTM D149 in the range of 100 to 500 kV / mm, 120 to 480 kV / mm, 140 to 450 kV / mm, 150 to 400 kV / mm, 170 to 350 kV / mm, 190 to 320 kV / mm, 200 to 300 kV / mm, 210 to 280 kV / mm, or 220 to 250 kV / mm. The dielectric breakdown voltage may be measured by methods known in the industry. In one example, the dielectric breakdown voltage may be measured as follows: The polyimide is prepared into a film specimen, and all moisture is removed from the film in an oven at 100°C or lower. After that, the specimen was cut to an appropriate size, and an insulation breakdown tester (Automated Test Set for Insulating Materials, equipment conforming to ASTM D149, PHENIX TECHNOLOGIES 6CCE50-5) was used. After placing the specimen on the sample stage, the limit dielectric strength of the insulator was measured by increasing the voltage from 0 at a constant rate.

[0107] Furthermore, the present application relates to a coating. The coating may comprise a polyimide which is a cured product of the aforementioned polyamic acid composition. The coating may comprise a substrate; and a polyimide coated on the substrate. The polyimide may be, for example, coated and cured on the surface of a conductor.

[0108] The above description may be a conductor. The conductor may be a copper wire made of copper or a copper alloy, but may also include a conductor made of other metal materials such as silver wire, or various metal-plated wires such as aluminum or tin-plated wires. The thickness of the conductor and the coating may comply with the KSC 3107 standard. The diameter of the conductor may be in the range of 0.3 to 3.2 mm, and the standard coating thickness of the coating (average value of the maximum and minimum coating thicknesses) may be 21 to 194 μm for Type 0, 14 to 169 μm for Type 1, and 10 to 31 μm for Type 2. The cross-sectional shape of the conductor may be a round wire, a flat wire, a hexagonal wire, etc., but is not limited to these.

[0109] In one example, the coating may include the step of coating a polyamic acid composition on a conductor surface; and the step of imidizing the polyamic acid composition coated on the conductor surface.

[0111] The present invention may also provide an electronic device comprising the above-mentioned coating. Effects of the invention

[0112] The present application provides a polyamic acid composition capable of simultaneously realizing excellent storage stability, low dielectric constant, heat resistance, insulation, and mechanical properties under harsh conditions such as high temperature, a polyimide which is a cured product of the composition, a coating material comprising the polyimide, a coated wire comprising the coating material, and an electronic device comprising the coated wire. Specific details for implementing the invention

[0113] The present invention will be explained in more detail below through embodiments according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited by the embodiments presented below.

[0115] Example 1

[0116] Preparation of polyamic acid compositions

[0117] N-methyl-pyrrolidone (NMP) was introduced into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge pipe while injecting nitrogen, and the temperature of the reactor was set to 40°C. Then, 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), pyromellitic dianhydride (PMDA), and modified pyromellitic dianhydride (PMDA*) were introduced and confirmed to be completely dissolved. Subsequently, 1,4-diaminobenzene (or paraphenylenediamine, PPD) was introduced, and the polymerization reaction was carried out in the same manner to prepare a polyamic acid composition.

[0118] The modified pyromellitic dianhydride (PMDA*) described above is represented by the following chemical formula 4.

[0119] [Chemical Formula 4]

[0120]

[0122] Polyimide film manufacturing

[0123] A polyimide film with a thickness of 30 μm was prepared by sequentially curing the above polyamic acid composition at 100°C for 20 minutes, at 150°C for 20 minutes, at 200°C for 20 minutes, at 300°C for 20 minutes, at 350°C for 20 minutes, and at 110°C for 60 minutes.

[0125] Examples 2 to 4 and Comparative Examples 1 to 2

[0126] Polyamic acid compositions and polyimide films of Examples 2 to 4 and Comparative Examples 1 to 2 were prepared in the same manner as in Example 1, except that the monomer and the content ratio thereof were changed as shown in Table 1 below.

[0127] diamine dianhydride Modified monomer ODA (mol%) PPD (Moll%) PMDA (mol%) PMDA*(mol%) Example 1 75 25 95 7 Example 2 75 25 8.5 Example 3 75 25 9 Example 4 75 25 10 Comparative Example 1 75 25 5 Comparative Example 2 75 25 0

[0128] Experimental Example 1 - Viscosity change rate at 23℃ and 30℃

[0129] The polyamic acid compositions of the examples and comparative examples were stored in sealed storage containers at temperatures of 23°C and 30°C for one week, and the rate of change in viscosity before and after storage was measured, respectively, and the results are shown in Table 2 below.

[0130] The viscosity before and after storage was measured using Haake’s Rheostress 600 at a shear rate of 1 / s, a temperature of 23°C (or 30°C), and a 1 mm plate gap.

[0132] Experimental Example 2 - Elongation, Tensile Strength, and Modulus

[0133] The elongation, tensile strength, and modulus of the polyimide films prepared in the examples and comparative examples were measured using a Universal Testing Machine (UTM), and the results are shown in Table 2 below.

[0135] Experimental Example 3 - Glass Transition Temperature

[0136] The glass transition temperature of the polyimide films prepared in the examples and comparative examples was measured using a Dynamic Mechanical Analysis (MA) device, and the results are shown in Table 2 below.

[0138] Experimental Example 4 - 5% Pyrolysis Temperature

[0139] The 5% thermal decomposition temperature of the polyimide films prepared in the examples and comparative examples was measured using a GA (Thermo Gravimetric Analysis) device, and the results are shown in Table 2 below.

[0141] Experimental Example 5 - Coefficient of Thermal Expansion (CTE)

[0142] The coefficient of thermal expansion of the polyimide films prepared in the examples and comparative examples was measured using a TMA (Thermo Mechanical Analysis) device, and the results are shown in Table 2 below.

[0144] Experimental Example 6 - Dielectric Constant

[0145] The dielectric constants of the polyimide films prepared in the examples and comparative examples were measured according to ASTM D150, and the results are shown in Table 2 below.

[0147] Experimental Example 7 - Dielectric Breakdown Voltage

[0148] The polyimide films prepared in the examples and comparative examples were prepared as specimens, and all moisture was removed from the films in an oven at 100°C or lower. Afterward, the specimens were cut to an appropriate size, and an Automated Test Set for Insulating Materials (equipment conforming to ASTM D149, PHENIX TECHNOLOGIES 6CCE50-5) was used. After placing the specimens on the sample stage, the limit dielectric strength of the insulator was measured by increasing the voltage from 0 at a constant rate, and the results are shown in Table 2 below.

[0150] Viscosity change rate (%) at 23℃ Viscosity change rate (%) at 30℃ Tensile strength (MPa) Modulus (GPa) Growth Rate (%) Glass transition temperature (°C) 5% Pyrolysis Temperature (°C) Coefficient of thermal expansion (ppm / ℃) genetic constant Dielectric breakdown voltage (kV / mm) Example 1 8 18 185 3.2 56 402 561 27 3.5 244 Example 2 2 3 154 3.1 48 412 556 29 3.5 244 Example 3 -3 2 140 3.0 32 385 568 28 3.6 240 Example 4 7 10 123 3.2 13 380 558 28 3.5 229 Comparative Example 1 28 51 200 3.2 63 414 556 27 3.6 252 Comparative Example 2 35 80 Unmeasurable

[0152] As confirmed in Table 2 above, Comparative Example 1 is a sample containing relatively less modified monomer compared to the Examples, and the viscosity change rate values ​​at 23°C and 30°C were 28% and 51%, respectively, showing results that exceeded the upper limits of 25% and 30%. In addition, even though the molar ratio of diamine to dianhydride was close to 1:1, the modified monomer was not sufficiently included, so the desired storage stability could not be secured, resulting in a viscosity change rate value exceeding the upper limit.

[0153] In addition, Comparative Example 2 is a sample that does not contain modified monomers, and the viscosity change rate values ​​at 23°C and 30°C were 35% and 80%, respectively, showing results exceeding the upper limits of 25% and 30%. The molar ratio of diamine to dianhydride was 100:95, which is lower than the general mixing ratio of 1:1, and because the molecular weight was low, no film was formed, so other physical properties could not be measured.

Claims

Claim 1 A polyamic acid having a diamine monomer and a dianhydride monomer as polymerization units, and a modified monomer represented by the following chemical formula 1, wherein the modified monomer is included in a range of 6 to 15 mol% with respect to 100 mol% of the diamine monomer of the polyamic acid, the molar ratio (A:B) of the dianhydride monomer (A) of the polyamic acid and the modified monomer (B) is in the range of 1:0.06 to 1:0.15, and the viscosity change rate (△V) at 23°C of the following general formula 1 23℃ ) satisfies -25% to +25%, and the viscosity change rate at 30℃ of the following general formula 2 (△V 30℃ Polyamic acid composition satisfying -30% to +30%: [Chemical Formula 1] In the above Chemical Formula 1, A1 to A4 are each independently a hydroxyl group (-OH), an amine group (-NH2), an alkoxy group, or an oxygen anion (-O - Selected as any one of ), wherein in Formula 1, X is a tetravalent aliphatic ring, a tetravalent heteroaliphatic ring, a tetravalent aromatic ring, or a tetravalent heteroaromatic ring, and the carbon atom of the carbonyl group of Formula 1 is connected to a ring constituent atom of the aliphatic ring, heteroaliphatic ring, aromatic ring, or heteroaromatic ring, and the aliphatic ring, the heteroaliphatic ring, the aromatic ring, or the heteroaromatic ring are single rings or are joined together to form a polycyclic 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)-, -S(=O)2- and -Si(R a Connected by a linker comprising one or more divalent substituents selected from the group consisting of )2-, where R a is hydrogen or an alkyl group: [General Formula 1]△V 23℃ = (V2 - V1) / V1 × 100 In the above general formula 1, △V 23℃ ΔV represents the rate of change of the viscosity (V2) of a polyamic acid composition stored for one week in a sealed storage container at a temperature of 23°C, based on the viscosity (V1) of the polyamic acid composition before storage: [General Formula 2] ΔV 30℃ = (V4 - V3) / V3 × 100 In the above general formula 2, △V 30℃ This represents the rate of change of the viscosity (V4) of the polyamic acid composition stored for one week in a sealed storage container at a temperature of 30°C, based on the viscosity (V3) of the polyamic acid composition before storage. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 The polyamic acid composition of claim 1, wherein the dianhydride monomer comprises at least one compound represented by the following chemical formula 2: [Chemical Formula 2] In the above Chemical Formula 2, Y is a tetravalent aliphatic ring, a tetravalent heteroaliphatic ring, a tetravalent aromatic ring, or a tetravalent heteroaromatic ring, and the carbon atom of the carbonyl group of Chemical Formula 2 is connected to a ring constituent atom of the aliphatic ring, heteroaliphatic ring, aromatic ring, or heteroaromatic ring, and the aliphatic ring, the heteroaliphatic ring, the aromatic ring, or the heteroaromatic ring is a single ring; or is joined to form a polycyclic ring; or has 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)-, -S(=O)2- and -Si(R a Connected by a linker comprising one or more divalent substituents selected from the group consisting of )2-, where R a is hydrogen or an alkyl group. Claim 6 The polyamic acid composition of claim 1, wherein the diamine monomer comprises at least one compound represented by the following chemical formula 3: [Chemical Formula 3] In the above chemical formula 3, any one of B1 to B5 is an amino group, and the remainder represents hydrogen; a halogen; a hydroxyl group; a carboxyl group; or an alkyl group substituted with or unsubstituted with a halogen. Claim 7 delete Claim 8 A polyamic acid composition according to claim 1, wherein the solid content is within the range of 5 to 40 weight%. Claim 9 In claim 1, a temperature of 30℃ and 1s -1 A polyamic acid composition having a viscosity within the range of 1,000 to 50,000 cp measured under shear rate conditions. Claim 10 Polyimide, which is a cured product of a polyamic acid composition according to claim 1. Claim 11 In claim 10, the polyimide having an elongation measured using a Universal Testing Machine (UTM) device within the range of 10% to 60%. Claim 12 In claim 10, the polyimide has a coefficient of thermal expansion (CTE) measured using a Thermo Mechanical Analysis (TMA) device within the range of 0.1 ppm / ℃ to 50 ppm / ℃. Claim 13 In claim 10, the polyimide having a glass transition temperature within the range of 200 to 500°C as measured using a DMA (Dynamic mechanical analysis) device. Claim 14 In claim 10, the polyimide having a 5% thermal decomposition temperature measured using a TGA (Thermo Gravimetric Analysis) device within the range of 450 to 650℃. Claim 15 In claim 10, the polyimide having a dielectric constant (Dk) measured according to ASTM D150 in the range of 1 to 5. Claim 16 In claim 10, the polyimide having a dielectric breakdown voltage (BDV) measured according to ASTM D149 within the range of 100 to 500 kV / mm. Claim 17 A substrate; and a coating comprising a polyimide of any one of claims 10 to 16 coated on the substrate. Claim 18 In claim 17, the above description is a conductive coating. Claim 19 An electronic device comprising a covering according to claim 17.

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