Polyimide varnish with excellent adhesive strength and polyimide film containing the same

Abstract

To provide a polyimide varnish that has excellent adhesive strength and adhesion to conductors such as copper, and is therefore highly useful as an insulating coating material for electrical wires.SOLUTION: There is provided a polyimide varnish, which includes a dianhydride monomer and a diamine monomer as polymerized units, wherein the diamine monomer includes a first diamine monomer and a second diamine monomer, and the second diamine monomer is represented by Chemical Formula 1, wherein A may be unsubstituted or substituted and is hydrogen, halogen, C1 to C6 alkyl, phenyl, (C1 to C6 alkylene)-(C3 to C5 heteroaryl), (C1 to C6 alkylene)-COOH, or -OH, where the substitution is to halogen, C1 to C3 alkyl, C1 to C3 haloalkyl, or oxo (=O).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyimide varnish and a polyimide film containing the same, and more particularly to a polyimide varnish having excellent adhesive strength to a conductor and a polyimide film containing the same. [Background technology]

[0002] Generally, polyimide (PI) resin refers to a highly heat-resistant resin produced by solution polymerization of aromatic dianhydrides and aromatic diamines or aromatic diisocyanates to produce polyamic acid derivatives, followed by ring-closing dehydration at high temperatures to form imidized polyimides. Polyimide resins are insoluble, infusible, and ultra-high heat-resistant resins with excellent thermal oxidation resistance, heat resistance, radiation resistance, low-temperature resistance, and chemical resistance. They are widely used in advanced heat-resistant materials for automobiles, aviation, and space radiation, as well as in electronic materials such as insulating coatings, insulating films, semiconductors, and TFT-LCD electrode protection films. Recently, they have also been used in display materials such as optical fibers and liquid crystal alignment films, and in transparent electrode films, either containing conductive fillers within the film or coated on the surface.

[0003] In particular, insulated wires used as coil windings for motors and other devices require the insulating layer (insulating coating) that covers the conductor to have excellent insulation properties, adhesion to the conductor, heat resistance, mechanical strength, and other characteristics, and polyimide is used as the resin that forms the insulating layer.

[0004] However, despite their excellent physical properties, typical polyimide resins have poor adhesive strength with conductors, which can lead to poor appearance when forming insulating coatings. Thus, there are many drawbacks to improving the properties required of polyimide varnishes and polyimide resins produced therefrom. In particular, improving one property generally results in a decrease in other properties. Therefore, satisfying various properties simultaneously is a challenge that is continually being researched in the related technical field.

[0005] Therefore, there is a high demand for a polyimide varnish for coating conductors that simultaneously satisfies the heat resistance, insulating properties, and mechanical properties of polyimide and has excellent adhesive strength to conductors. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a polyimide varnish that contains an azine-based diamine and thus has excellent conductor wire adhesion and adhesion.

[0007] The present invention also provides a cured polyimide product (or film) produced by curing the polyimide varnish.

[0008] The present invention also provides a polyimide coated article comprising a cured product of the polyimide varnish. [Means for solving the problem]

[0009] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated and described in detail, but it should be understood that this does not limit the present invention to the specific embodiments, and that the present invention includes all modifications, equivalents, and alternatives that fall within the spirit and technical scope of the present invention.

[0010] The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" and the like specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0011] Whenever an amount, concentration, or other value or parameter is given herein by a list of ranges, preferred ranges, or upper preferred values ​​and lower preferred values, that should be understood to specifically disclose all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are otherwise disclosed.

[0012] Where a range of numerical values ​​is recited herein, unless otherwise stated, it is intended that the endpoints of the range and any values ​​within the range be included. The scope of the invention is not limited to the specific values ​​recited when defining the range.

[0013] As used herein, "dianhydride" is intended to include precursors or derivatives thereof, but may also be referred to as "dianhydride acids," "dianhydrides," or "acid dianhydrides," which may not technically be dianhydrides but nevertheless react with diamines to form polyamic acids, which in turn can be converted to polyimides.

[0014] As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but which nevertheless react with dianhydride acids to form polyamic acids, which in turn can be converted to polyimides.

[0015] In the present invention, the term "halogen" refers to a substituent selected from fluoro (F), chloro (Cl), bromo (Br) and iodo (I).

[0016] In the present invention, the term "unsubstituted" means not substituted with any substituent, and is in the state of being absent or hydrogen.

[0017] As used herein, the term "substituted" refers to a moiety having a substituent group replacing a hydrogen atom on one or more carbon atoms of the main chain. "Substituted" or "substituted with" is defined to include the implicit proviso that such substitution leads to a stable compound, e.g., a compound that does not spontaneously deform by rearrangement, cyclization, elimination, etc., depending on the acceptability of the substituted atom and the substituent.

[0018] In the present invention, "C x-y " means having at least x but no more than y carbon atoms.

[0019] In the present invention, the term "C1-C6 alkyl" refers to a C1-C6 straight or branched saturated hydrocarbon group, such as methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, etc. Preferred alkyl groups contain about 1, 2, 3, 4, 5 or 6 carbon atoms in the chain.

[0020] In the present invention, the term "C1-C6 alkylene" may be a straight chain or branched chain and specifically refers to a saturated aliphatic hydrocarbon such as, for example, a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, a sec-butylene group, a t-butylene group, an n-pentylene group, or an n-hexylene group. An "alkylene" may be unsubstituted or optionally substituted with one or more substituents which may be the same or different.

[0021] In the present invention, the term "C1-C3 haloalkyl" refers to a C1-C3 straight-chain or branched-chain saturated hydrocarbon in which at least one hydrogen atom of the C1-C3 straight-chain or branched-chain saturated hydrocarbon has been replaced with a halogen atom (i.e., F, Cl, Br, or I). For example, "C1-C3 haloalkyl" may be, but is not limited to, CH2F, CHF2, CF3, etc.

[0022] In the present invention, the term "C3-C5 heteroaryl" refers to an optionally substituted aromatic ring containing 3 to 5 carbon atoms, in which at least one ring carbon atom is replaced with a heteroatom selected from oxygen (O), nitrogen (N), and sulfur (S), or an aromatic ring fused to one or more rings (e.g., a bicyclic or tricyclic ring), such as a heteroaryl ring, an aryl ring, a heterocyclic ring, or a carbocyclic ring, each of which may have optional substituents. Examples of heteroaryls include, but are not limited to, pyrrole, pyrazole, imidazole, furan, isoxazole, dioxazole, thiophene, isothiazole, thiazole, pyridine, pyridazine, pyrimidine, pyrazine, or triazine (e.g., 1,2,4-triazine, 1,3,5-triazine). The heteroaryl may be substituted or unsubstituted.

[0023] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted in an ideal or overly formal sense unless expressly defined in this application. Specific details for realizing the above invention are described below.

[0024] Polyimide Varnish The present invention relates to a polyimide varnish that has improved adhesive strength and adhesion to conductor wires and can be used for conductor coating.

[0025] In one aspect of the present invention, there is provided a polyimide varnish comprising a dianhydride monomer and a diamine monomer as polymerization units, the diamine monomer comprising a first diamine monomer and a second diamine monomer, and the second diamine monomer being represented by the following Chemical Formula 1:

[0026] [ka]

[0027] In chemical formula 1, A may be unsubstituted or substituted and is hydrogen, halogen, C-C alkyl, phenyl, (C-C alkylene)-(C-C heteroaryl), (C-C alkylene)-COOH, or —OH, where the substitution is to halogen, C-C alkyl, C-C haloalkyl, or oxo (═O).

[0028] Specifically, A is hydrogen, fluoro (F), chloro (Cl), bromo (Br), methyl, ethyl, propyl, phenyl, (C1-C6 alkylene)-imidazolyl, (C1-C6 alkylene)-COOH, or -OH, and A may be unsubstituted or substituted with at least one or more of methyl, ethyl, trifluoromethyl, or oxo (=O).

[0029] More specifically, A is hydrogen, fluoro (F), chloro (Cl), methyl, ethyl, propyl, phenyl, methylene-imidazolyl, ethylene-imidazolyl, propylene-imidazolyl, methylene-COOH, ethylene-COOH, propylene-COOH, butylene-COOH, or —OH, and A may be unsubstituted or substituted with at least one or more of methyl, ethyl, trifluoromethyl, or oxo (═O).

[0030] More specifically, A may be hydrogen, fluoro (F), chloro (Cl), methyl, ethyl, propyl, phenyl, methylene-imidazolyl substituted with methyl, ethylene-imidazolyl substituted with methyl, propylene-imidazolyl substituted with methyl, methylene-COOH substituted with oxo (=O), ethylene-COOH substituted with oxo (=O), propylene-COOH substituted with oxo (=O), butylene-COOH substituted with oxo (=O), or -OH.

[0031] In the above Chemical Formula 1, the ratio of carbon to nitrogen (C / N) may be 0.5 to 2.5, preferably 0.6 to 2.1, and more preferably 0.7 to 1.9.

[0032] The second diamine monomer may include a triazine-based diamine, specifically, 1,3,5-triazine-2,4-diamine, 6-chloro-1,3,5-triazine-2,4-diamine, 4,6-diamino-1,3,5-triazin-2-ol, 6-methyl-1,3,5-triazine-2,4-diamine, ne), 6-Phenyl-1,3,5-triazine-2,4-diamine, 6-[2-(2-methylimidazol-1-yl)ethyl]-1,3,5-triazine-2,4-diamine, and 4-(4,6-diamino-1,3,5-triazin-2-yl)-4-oxobutanoic acid.

[0033] In one embodiment, the second diamine monomer can be 6-chloro-1,3,5-triazine-2,4-diamine alone, 4,6-diamino-1,3,5-triazin-2-ol alone, 6-methyl-1,3,5-triazine-2,4-diamine alone, 2,6-diamino-4-phenyl-1,3,5-triazine alone, 6-[2-(2-methylimidazolyl-1-yl)ethyl]-1,3,5-triazine-2,4-diamine alone, or 4-(4,6-diamino-1,3,5-triazin-2-yl)-4-oxobutanoic acid alone.

[0034] The secondary diamine monomer, which contains a functional group capable of forming a coordinate bond with Cu, is incorporated into the polyimide chain to improve adhesion, thereby preventing peeling of the coating layer due to poor adhesion between the conductor and polyimide insulator. Furthermore, the physical properties of the polyimide film can be tailored to suit the purpose after the varnish is cured.

[0035] In the present invention, the content of the first diamine monomer may be more than 80 mol% and 99.9 mol% or less, and the content of the second diamine monomer may be 0.1 mol% or more and less than 20 mol%, relative to 100 mol% of the total content of the diamine monomers.

[0036] Preferably, the content of the first diamine monomer is more than 90 mol% and 99.9 mol% or less, and the content of the second diamine monomer is 0.1 mol% or more and less than 10 mol%, relative to 100 mol% of the total content of the diamine monomers.

[0037] More preferably, the content of the first diamine monomer may be 90.5 mol% to 99 mol%, 91 mol% to 98 mol%, or 91 mol% to 95 mol%, and the content of the second diamine monomer may be 1 mol% to 9.5 mol%, 2 mol% to 9 mol%, or 5 mol% to 9 mol%, relative to 100 mol% of the total content of the diamine monomers.

[0038] When the content of the second diamine monomer is in the range of 0.1 mol % or more and less than 10 mol %, a film is formed without cracking when the varnish is cured, and the film has excellent physical properties, which is preferable.

[0039] Furthermore, the content of the second diamine monomer may be 0.1 mol% or more and less than 10 mol% relative to the total content of the diamine monomers (100 mol%). For example, the lower limit may be 0.2 mol% or more, 0.5 mol% or more, 1.0 mol% or more, 1.5 mol% or more, 2.0 mol% or more, 3.0 mol% or more, 4.0 mol% or more, or 5.0 mol% or more, and the upper limit may be 9.9 mol% or less, 9.5 mol% or less, 9 mol% or less, 8 mol% or less, 7 mol% or less, 6 mol% or less, or 5 mol% or less.

[0040] Furthermore, the content of the second diamine monomer may be 0.05 mol % or more and less than 10 mol % relative to 100 mol % of the entire polyimide varnish.

[0041] In the present invention, the dianhydride monomer is selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), benzophenonetetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (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, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimeric monoester acid anhydride), p -Biphenylene bis(trimeric 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)benzene dianhydride The compound may include one or more selected from the group consisting of 2,2-bis[(3,4-dicarboxyphenoxy)biphenyl]dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride.

[0042] Specifically, the dianhydride monomer may include one or more selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), and benzophenonetetracarboxylic dianhydride (BTDA), and preferably includes pyromellitic dianhydride (PMDA).

[0043] In addition, the first diamine monomer may be selected from the group consisting of paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), 2,2-bisaminophenoxyphenylpropane (BAPP), metaphenylenediamine (MPD), 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (MDA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2' -Dimethyl-4,4'-diaminobiphenyl (m-tolidine), 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'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-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, 2,2-bis(3- aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 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 (TPE-R), 1,4-bis(3-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenylphenoxy)benzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide) bis(4-aminophenylsulfone)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, 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-amino phenoxy)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-aminophen 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-( The fluorocarbon polymer may include one or more selected from the group consisting of 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0044] Specifically, the first diamine monomer may include at least one selected from the group consisting of paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), metaphenylenediamine (MPD), 2,2-bisaminophenoxyphenylpropane (BAPP), and 1,3-bis(4-aminophenoxy)benzene (TPE-R), and preferably includes at least one selected from the group consisting of 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and mixtures thereof.

[0045] In one embodiment, the first diamine monomer may be 4,4'-diaminodiphenyl ether (ODA) alone or a combination of paraphenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (ODA).

[0046] In one embodiment, the polyimide varnish may contain pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), and 6-methyl-1,3,5-triazine-2,4-diamine as polymerized units.

[0047] In one embodiment, the polyimide varnish may include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), and 6-phenyl-1,3,5-triazine-2,4-diamine as polymerized units.

[0048] In one embodiment, the polyimide varnish can include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), and 6-[2-(2-methylimidazolyl-1-yl)ethyl]-1,3,5-triazine-2,4-diamine as polymerized units.

[0049] In one embodiment, the polyimide varnish may include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), and 6-chloro-1,3,5-triazine-2,4-diamine as polymerized units.

[0050] In one embodiment, the polyimide varnish may include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), and 4,6-diamino-1,3,5-triazin-2-ol as polymerized units.

[0051] In one embodiment, the polyimide varnish can include pyromellitic dianhydride (PMDA), 4,4′-diaminodiphenyl ether (ODA), and 4-(4,6-diamino-1,3,5-triazin-2-yl)-4-oxobutanoic acid as polymerized units.

[0052] In one embodiment, the polyimide varnish may contain pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and 6-methyl-1,3,5-triazine-2,4-diamine as polymerized units.

[0053] In one embodiment, the polyimide varnish can include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and 6-phenyl-1,3,5-triazine-2,4-diamine as polymerized units.

[0054] In one embodiment, the polyimide varnish may include pyromellitic dianhydride (PMDA), 4,4′-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and 6-[2-(2-methylimidazolyl-1-yl)ethyl]-1,3,5-triazine-2,4-diamine as polymerized units.

[0055] In one embodiment, the polyimide varnish may contain pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and 6-chloro-1,3,5-triazine-2,4-diamine as polymerized units.

[0056] In one embodiment, the polyimide varnish can include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and 4,6-diamino-1,3,5-triazin-2-ol as polymerized units.

[0057] In one embodiment, the polyimide varnish may include pyromellitic dianhydride (PMDA), 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and 4-(4,6-diamino-1,3,5-triazin-2-yl)-4-oxobutanoic acid as polymerized units.

[0058] In the present invention, the content of 4,4'-diaminodiphenyl ether (ODA) may be 50 mol% or more, specifically 53 mol% or more, 55 mol% or more, 58 mol% or more, 60 mol% or more, 62 mol% or more, 65 mol% or more, 68 mol% or more, or 70 mol% or more, relative to 100 mol% of the total content of the diamine monomers. Here, the upper limit may be less than 100 mol%, specifically 99.9 mol% or less.

[0059] Furthermore, the content of paraphenylenediamine (PPD) may be 50 mol% or less, specifically 45 mol% or less, 40 mol% or less, 38 mol% or less, 35 mol% or less, 33 mol% or less, 30 mol% or less, 28 mol% or less, or 25 mol% or less, relative to 100 mol% of the total content of the diamine monomers. Here, the lower limit may be 0 mol% or more, and 0 mol% may mean that paraphenylenediamine is not contained in the polyimide varnish.

[0060] Specifically, the copolymer may contain 70 to 99.9 mol% of 4,4'-diaminodiphenyl ether (ODA), 0 to 25 mol% of paraphenylenediamine (PPD), and 0.1 to 19.9 mol% of a secondary diamine monomer, relative to 100 mol% of the total content of the diamine monomers.

[0061] The molar ratio of the dianhydride monomer to the diamine monomer may be 6:4 to 4:6, preferably 5.5:4.5 to 4.5:6.5, and more preferably 5:5.

[0062] The polyimide varnish may have a polyimide solids content of 10 to 50 wt%. The lower limit of the polyimide solids content may be, for example, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, or 15 wt% or more, and the upper limit may be, for example, 48 wt% or less, 45 wt% or less, 43 wt% or less, 40 wt% or less, 38 wt% or less, 35 wt% or less, 33 wt% or less, or 30 wt% or less. Adjusting the polyimide solids content of the polyimide varnish can control the increase in viscosity and shorten the process time during the curing process.

[0063] In addition, the polyimide varnish of the present invention further comprises 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. For example, the organic solvent may be an aprotic polar solvent.

[0064] Specifically, the organic solvent may include one or more selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), 3-methoxy-N,N-dimethylpropanamide (KJCMPA), p-chlorophenol, o-chlorophenol, γ-butyrolactone (GBL), diglyme, naphthalene, perchloroethylene, methyl butyl ketone (MBK), oxocyclohexanol, 1-methylcyclohexanol, styrene, 2-methoxyethanol, ethylene glycol monoethyl ether, chlorobenzene (phenyl chloride), cresol, xylene, tetrachloroethylene, and naphtha. Preferably, N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), cresol, xylene, naphtha, and the like can be used.

[0065] The organic solvent may further include a modifier containing a hydroxyl group (OH) or an amine group (NH). Examples of modifiers containing a hydroxyl group (OH) or an amine group (NH) include ethylamine, triethanolamine, dimethylamine, trimethylamine, diethylenetriamine, ethylenediamine, tributylamine, pyridine, pyrrolidine, methanol, ethanol, propanol, isopropanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, hexanol, octanol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, allyl alcohol, crotyl alcohol, propargyl alcohol, ethylene glycol, propylene glycol, benzyl alcohol, and phenol. The modifier may react with the dianhydride monomer to control the reactivity.

[0066] The polyimide varnish of the present invention can further contain nanosilica surface-modified with an organosilane, which prevents aggregation of inorganic particles in the polyimide varnish and enhances the interaction with the solid content (polyamic acid) through the functional groups of the compound, thereby improving dispersibility and miscibility.

[0067] The nanosilica surface-modified with the organosilane may have an average particle size of 1 to 200 nm, specifically 5 to 150 nm, 5 to 100 nm, 5 to 70 nm, 10 to 50 nm, or 10 to 30 nm. The average particle size can be measured using equipment such as BET, SEM, and zeta potential.

[0068] The organic silane of the nanosilica surface-modified with the organic silane may be methyltrimethoxysilane, hexamethyldisiloxane, n-octyltrimethoxysilane, n-octyltriethoxysilane, isooctyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-(methacryloxy)propyltriethoxysilane, 3-(methacryloxy)propylmethyldimethoxysilane, 3-(acryloxypropyl)methyldimethoxysilane, or 3-(methacryloxy)propyldimethyl Ethoxysilane, styrylethyltrimethoxysilane, phenyltriethoxysilane, p-tolyltriethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylethoxysilane, vinylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriphenoxysilane, vinyltri-t-butoxysilane, vinyltris(isobutoxy)silane, vinyltriisoprofenoxysilane, vinyltris(2-methoxyethoxy)silane, diisopropylethylamine phenyltrimethoxysilane (N,N-Diisopropylethylamine The silane may include one or more selected from the group consisting of N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTMS ...MS), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTMS), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTMS), N-phenyl-3-aminopropyltrimethoxysilane (PAPTMS), N-phenyl-3-aminopropyltrimethoxysilane (PAPTES), N-phenyl-3-aminopropyltrimethoxysilane (PAPTMS), N-phenyl-3-aminopropyltrimethoxysilane (PAPTMS), N-phenyl

[0069] The nanosilica surface-modified with the organosilane may have a compound containing at least one phenyl group at its terminal and a compound containing at least one amine group, hydroxy group, thiol group, or epoxide group at its terminal bound to the surface of the nanosilica. Specifically, the compound containing at least one phenyl group at its terminal may be phenyltrimethoxysilane (PTMS) or phenylaminopropyltrimethoxysilane (N-Phenyl-3-aminopropyltrimethoxysilane (PAPTES)). Furthermore, the compound containing at least one amine group, hydroxy group, thiol group, or epoxide group at its terminal may be glycidoxypropyltrimethoxysilane (GPTMS) or aminopropyltrimethoxysilane ((3-Aminopropyl)trimethoxysilane (APTMS)).

[0070] The nanosilica surface-modified with an organosilane can be produced by subjecting nanosilica to a surface treatment with an organosilane. For example, nanosilica can be obtained by heating the organosilane under acidic or basic conditions and subjecting the surface to a surface treatment for approximately 1 to 24 hours. Alternatively, surface modification can be achieved by other known methods, such as mixing the organosilane with a solvent and then reacting at a temperature of 10 to 100°C or 20 to 60°C for 1 to 10 hours or 1 to 5 hours to obtain surface-modified nanosilica. To bond two or more compounds to the surface of nanosilica, the above methods can be used, respectively.

[0071] The nanosilica surface-modified with the organosilane may be contained in an amount of 0.1 to 12.0 parts by weight per 100 parts by weight of the polyimide varnish. For example, the lower limit of the content of the nanosilica surface-modified with the organosilane may be 0.2 parts by weight or more, 0.3 parts by weight or more, 0.35 parts by weight or more, 0.40 parts by weight or more, 0.45 parts by weight or more, 0.50 parts by weight or more, or 0.55 parts by weight or more. The upper limit may be, for example, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1.5 parts by weight or less, 1.25 parts by weight or less, 1.20 parts by weight or less, 1.15 parts by weight or less, 1.10 parts by weight or less, 1.05 parts by weight or less, 1.0 parts by weight or less, 0.95 parts by weight or less, 0.9 parts by weight or less, 0.85 parts by weight or less, 0.8 parts by weight or less, 0.79 parts by weight or less, 0.78 parts by weight or less, 0.77 parts by weight or less, or 0.76 parts by weight or less. By containing the nanosilica within the above range, it is effective in improving properties and can prevent deterioration of physical properties due to aggregation and reduced usability, which is preferable.

[0072] The polyimide varnish of the present invention may further contain an aromatic carboxylic acid, which may be further added to form an optimal molar ratio.

[0073] The aromatic carboxylic acid may include one or more selected from the group consisting of pyromellitic acid (PMA), 3,3',4,4'-biphenyltetracarboxylic acid (BPTA), 1,2,3,4-benzenetetracarboxylic acid, benzophenone-3,3',4,4'-tetracarboxylic acid, pyrazinetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, and naphthalene-1,4,5,8-tetracarboxylic acid. In one embodiment, pyromellitic acid (PMA) is used.

[0074] The content of the aromatic carboxylic acid that can be further contained may be 0 to 1.0 mol%, specifically 0 to 0.8 mol%, more preferably 0.1 to 0.6 mol%, where 0 mol% may mean that the aromatic carboxylic acid is not contained in the polyimide varnish.

[0075] Polyimide varnish and its cured product In the present invention, the tensile strength, modulus, and elongation percentage, which are mainly used as criteria for determining the mechanical properties of the polyimide, were confirmed.

[0076] The tensile strength of the polyimide varnish according to the present invention may be 100 MPa or more after curing, and the lower limit of the tensile strength may be, for example, 102 MPa, 103 MPa, 105 MPa, 107 MPa, 108 MPa, 109 MPa, or 110 MPa or more. The upper limit is not particularly limited, but may be 400 MPa or less. The tensile strength was measured using an Instron 5564 UTM instrument manufactured by Instron Corporation, using samples 220 mm long and 10 mm wide, with a grip spacing of 50 mm and a speed of 50 mm / min, according to ASTM D-882, and the average of 10 samples was calculated.

[0077] The polyimide varnish according to the present invention may have a modulus of 2.0 GPa or more after curing. The lower limit of the modulus may be, for example, 2.1 GPa or more, 2.2 GPa or more, 2.3 GPa or more, 2.4 GPa or more, or 2.5 GPa or more, and the upper limit is not particularly limited, but may be 10 GPa or less. The modulus was measured according to ASTM D-882 standard using an Instron 5564 UTM instrument manufactured by Instron Corporation, with samples 220 mm long and 10 mm wide prepared, at a speed of 50 mm / min, and the average of 10 samples was calculated.

[0078] The polyimide varnish according to the present invention may have an elongation of 8% or more after curing, and the lower limit of the elongation may be, for example, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, or 12% or more. The upper limit is not particularly limited, but may be 80% or less. In one embodiment, the elongation can be measured in accordance with ASTM D-882 standard using an Instron 5564 UTM instrument manufactured by Instron Corporation, where a sample having a length of 220 mm and a width of 10 mm is prepared and the elongation is measured at a rate of 50 mm / min.

[0079] In the present invention, the thermal decomposition temperature (Td), glass transition temperature (Tg), and coefficient of thermal expansion (CTE), which are mainly used as criteria for determining the thermal properties of the polyimide, were confirmed.

[0080] After curing, the polyimide varnish according to the present invention may have a glass transition temperature (Tg) of 300°C or higher, and the lower limit of the glass transition temperature may be, for example, 310°C±5°C, 320°C±5°C, 330°C±5°C, 340°C±5°C, or 350°C±5°C. The upper limit is not particularly limited, but may be 600°C or lower. The glass transition temperature can be measured for polyimide using DMA at a rate of 5°C / min.

[0081] The temperature at which a 1% weight loss occurs after curing of the polyimide varnish according to the present invention, i.e., the 1 wt% thermal decomposition temperature (Td), may be 340°C or higher, and the lower limit of the 1 wt% thermal decomposition temperature (Td) may be, for example, 342°C±2°C, 345°C±2°C, 350°C±2°C, 355°C±2°C, 360°C±2°C, 365°C±2°C, 370°C±2°C, 375°C±2°C, or 380°C±2°C or higher. Here, the upper limit is not particularly limited, but may be 600°C or lower. Furthermore, the temperature at which a 5% weight loss occurs, i.e., the 5 wt% thermal decomposition temperature (Td), may be 500°C or higher. The lower limit of the 5 wt% thermal decomposition temperature (Td) may be, for example, 510°C ± 2°C, 515°C ± 2°C, 520°C ± 2°C, 525°C ± 2°C, 530°C ± 2°C, 533°C ± 2°C, or 535°C ± 2°C. The upper limit is not particularly limited, but may be 750°C or lower. The thermal decomposition temperature can be measured using a thermogravimetric analyzer (Model Q50) manufactured by TA Corporation. Specifically, a polyimide is heated to 150°C at a rate of 10°C / min in a nitrogen atmosphere, and then maintained at the same temperature for 30 minutes to remove moisture. The temperature is then raised to 600°C at a rate of 10°C / min, and the temperature at which a 1% or 5% weight loss occurs can be measured.

[0082] After curing, the polyimide varnish according to the present invention may have a thermal expansion coefficient of 30 ppm / °C or more in the temperature range of 100°C to 350°C, and the lower limit of the thermal expansion coefficient may be, for example, 31 ppm / °C, 32 ppm / °C, 33 ppm / °C, 34 ppm / °C, or 35 ppm / °C or more. The upper limit is not particularly limited, but may be 70 ppm / °C or less. In one embodiment, the thermal expansion coefficient was measured using a TMA device, measuring the gradient in the temperature range of 100 to 250°C when the temperature was increased from room temperature to 350°C at a rate of 10°C / min.

[0083] In the present invention, the dielectric constant and dielectric breakdown strength, which are mainly used as criteria for determining the electrical properties of the polyimide, were confirmed.

[0084] The polyimide varnish according to the present invention may have a dielectric constant of 4 or less after curing, and the upper limit of the dielectric constant may be, for example, 3.9 or less, 3.85 or less, 3.8 or less, 3.75 or less, or 3.7 or less, and the lower limit may be, but is not particularly limited to, 2.0 or more. Here, the dielectric constant was measured at 10 GHz using a Keysight SPDR (Split Post Dielectric Resonator) measuring instrument.

[0085] After curing, the polyimide varnish according to the present invention may have a dielectric breakdown voltage (BDV) of 100 kV / mm or more, as measured according to the ASTM D149 standard. The lower limit of the dielectric breakdown voltage may be, for example, 105 kV / mm or more, 110 kV / mm or more, 115 kV / mm or more, 120 kV / mm or more, 125 kV / mm or more, 130 kV / mm or more, 135 kV / mm or more, 140 kV / mm or more, or 145 kV / mm or more. The upper limit is not particularly limited, but may be 500 kV / mm or less. Specifically, the dielectric breakdown voltage (BDV) was measured by pretreating the sample in an oven at 100°C to remove moisture, fixing the sample in a measuring device (Phenix, TECHNOLOGIES 6CCE50-5) set to a room temperature atmosphere, and applying a voltage of 10 kV AC to the electrodes while increasing the AC voltage at a constant rate from 0.

[0086] In the present invention, the peel strength and adhesive strength by a crosscut test, which are mainly used as criteria for determining the adhesiveness of the polyimide, were confirmed.

[0087] The polyimide varnish according to the present invention may have a peel strength of 3.0 N / cm or more after curing, and the lower limit of the peel strength may be, for example, 3.1 N / cm or more, 3.2 N / cm or more, 3.3 N / cm or more, 3.4 N / cm or more, or 3.5 N / cm or more. The lower limit is not particularly limited, but may be a level at which peeling is impossible. Here, the peel strength was measured using a UTM (Instron, model 5564) device at 23°C and 50% RH, while pulling at 50 mm / sec at a 90° peel angle.

[0088] After curing, the polyimide varnish according to the present invention may have an adhesion strength of 3B or more, preferably 4B or more, in accordance with ASTM D 3359, and although there is no particular upper limit, it may be 5B or less. The adhesion strength was measured by the method specified in ASTM D 3359.

[0089] The polyimide varnish of the present invention can be cured at a temperature of 23°C and 1 s -1 The viscosity measured under the shear rate condition may be in the range of 200 to 50,000 cP. Specifically, the lower limit of the viscosity of the polyimide solution may be 300 cP or more, 400 cP or more, 500 cP or more, 600 cP or more, 700 cP or more, 800 cP or more, 900 cP or more, or 1,000 cP or more, and the upper limit may be 45,000 cP or less, 40,000 cP or less, 35,000 cP or less, 30,000 cP or less, 25,000 cP or less, 20,000 cP or less, 18,000 cP or less, 16,000 cP or less, 15,000 cP or less, 14,000 cP or less, 13,000 cP or less, 12,000 cP or less, 11,000 cP or less, or 10,000 cP or less. By adjusting the viscosity range of the polyimide varnish, it is possible to produce a polyimide cured product with the desired physical properties with excellent processability.

[0090] In another aspect of the present invention, there is provided a cured polyimide product obtained by curing the polyimide varnish, and the cured polyimide product may be a polyimide film.

[0091] In another aspect of the present invention, there is provided a polyimide prepared by imidizing the polyimide varnish, and the polyimide may be in the form of a film.

[0092] In another aspect of the present invention, there is provided a polyimide coated article comprising the above-described cured polyimide.

[0093] In one embodiment, the method for producing the polyimide coating may include the steps of coating a surface of a conductor with a polyimide varnish and imidizing the polyimide varnish coated on the surface of the conductor.

[0094] The conductor may be a copper wire made of copper or a copper alloy, or may be a conductor made of other metal materials such as silver wire, or various metal-plated wires such as aluminum or tin-plated wire. The thickness of the conductor and coating may conform to the KS C 3107 standard. The diameter of the conductor may be within 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, but is not limited to, a ring wire, a rectangular wire, a hexagonal wire, or the like.

[0095] In another aspect of the present invention, there is provided an electric wire comprising the polyimide coating.

[0096] Specifically, the coated electric wire may include a polyimide coating produced by coating the surface of an electric wire with the polyimide varnish and imidizing the polyimide varnish. In one specific example, the coated electric wire may include an electric wire and a coating formed by coating the surface of the electric wire with the polyimide and imidizing the polyimide.

[0097] The present invention also provides an electronic device including the coated electric wire, such as an electric motor.

[0098] In another aspect of the present invention, a part is provided that includes a molded body formed from a polyimide varnish.

[0099] Specifically, the part may be an electronic circuit board member, a semiconductor device, a lithium ion battery member, a solar cell member, a fuel cell member, a motor winding, an engine peripheral member, a paint, an optical component, a heat dissipation material, an electromagnetic wave shielding material, a surge component, a dental material, a slide coating, or an electrostatic chuck. [Effects of the Invention]

[0100] The polyimide varnish of the present invention has excellent adhesive strength and adhesion to conductors such as copper, and is therefore highly useful as an insulating coating material for electrical wires. DETAILED DESCRIPTION OF THE INVENTION

[0101] Examples are presented below to aid in understanding the present invention. The following examples are provided to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention.

[0102] <Example> Example 1. Polyimide varnish Dimethylacetamide (DMAc) solvent was added to a nitrogen-purged reactor. Organosilane-surface-treated nanosilica (0.5-0.75 mol% based on diamine and dianhydride content) and pyromellitic dianhydride (PMDA) (92 mol%) were mixed and stirred at 40°C for 30 minutes. Next, triazine-based diamine was added and stirred for 30 minutes. After that, paraphenylenediamine (PPD) and / or 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) (8 mol%) were added and stirred at 40°C for approximately 1 hour. The resulting polyimide varnish (solids content: 15-30%, viscosity at 30°C: 1,000-10,000 cP) was polymerized.

[0103] Examples 2 to 24 and Reference Examples 1 to 6 Polyimide varnishes were produced in the same manner as in Example 1, except that the content of each component or the type of triazine-based diamine was changed as shown in Table 1.

[0104] Comparative Examples 1 and 2 Polyimide varnishes were produced in the same manner as in Example 1, except that the content of each component or the type of triazine-based diamine was changed as shown in Table 1.

[0105] [Table 1] TIFF2025181709000003.tif212170

[0106] The abbreviations in Table 1 are defined as follows: PMDA: Pyromeric dianhydride PPD: Paraphenylenediamine ODA: 4,4'-diaminodiphenyl ether

[0107] Example 25 Polyimide Film (Cured Polyimide) The polyimide varnish prepared in Example 1 was spun at a high speed of 2,000 rpm to remove air bubbles. Next, a spin coater was used to coat the polyimide varnish onto a soda-lime glass substrate to a thickness of 20 to 26 μm. The varnish was then cured under a nitrogen atmosphere at temperatures of 110°C (20 minutes), 150°C (20 minutes), 200°C (20 minutes), and 300°C (20 minutes) to obtain a polyimide film.

[0108] Examples 26 to 48 and Reference Examples 7 to 12 A polyimide film was produced in the same manner as in Example 25, except that the polyimide varnish was changed as shown in Table 2.

[0109] On the other hand, Reference Examples 7 to 12, which contained 10 mol% or more of a triazine diamine, specifically 6-Methyl-1,3,5-triazine-2,4-diamine, 6-Phenyl-1,3,5-triazine-2,4-diamine, 6-[2-(2-methylimidazol-1-yl)ethyl]-1,3,5-triazine-2,4-diamine, 4-(4,6-diamino-1,3,5-triazin-2-yl)-4-oxobutanoic acid, 6-chloro-1,3,5-triazine-2,4-diamine, or 4,6-Diamino-1,3,5-triazin-2-ol, cracked during the curing step and no film was formed.

[0110] Comparative Examples 3 and 4 A polyimide film was produced in the same manner as in Example 25, except that the polyimide varnish was changed as shown in Table 2.

[0111] [Table 2] TIFF2025181709000005.tif164170

[0112] <Experimental Example> Experimental Example 1: Evaluation of mechanical and thermal properties The cured products of Examples 25 to 48, which were obtained by curing the polyimide varnishes prepared in Examples 1 to 24, were examined for physical properties by the following methods, and the results are shown in Table 3 below.

[0113] (1) Tensile strength, Young's modulus, and elongation For the polyimide films manufactured in the examples and comparative examples, samples of 50 mm in length and 10 mm in width were prepared and measured at a speed of 50 mm / min according to ASTM D-882-91 using an Instron 5564 UTM instrument manufactured by Instron Corporation. The average of 10 samples was calculated, and the results are shown in Table 3 below.

[0114] (3) 1% weight loss temperature and 5% weight loss temperature (Td) Using a thermogravimetric analyzer (TA Q50 model), the polyimide films prepared in the examples and comparative examples 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 films were then heated to 600°C at a rate of 10°C / min, and the temperatures at which a 1% or 5% weight loss occurred were measured. The results are shown in Table 3 below.

[0115] (5) Glass transition temperature (Tg) The glass transition temperatures of the polyimide films prepared in the examples and comparative examples were measured using DMA at a rate of 5°C / min up to 350°C, and the results are shown in Table 3 below.

[0116] (6) Coefficient of thermal expansion (CTE) The polyimide films prepared in the examples and comparative examples were heated from room temperature to 350°C at a heating rate of 10°C / min using a TMA (Testerson Machinery) Q400 manufactured by TA Co., Ltd., and the gradient in the 100-250°C range was measured. The results are shown in Table 3 below.

[0117] [Table 3] TIFF2025181709000007.tif38170

[0118] It was confirmed from Table 3 that the polyimide films of Examples 25 to 48, which contained an appropriate amount of triazine-based diamine, had good mechanical and thermal properties.

[0119] Experimental example 2: Evaluation of electrical characteristics The cured products of Examples 25 to 48, which were obtained by curing the polyimide varnishes prepared in Examples 1 to 24, were examined for physical properties by the following methods, and the results are shown in Table 4 below.

[0120] (1) Dielectric constant The dielectric constant of the polyimide films manufactured in the examples and comparative examples was measured at 10 GHz using a Keysight SPDR (Split Post Dielectric Resonator) measuring instrument at 23°C and 50% RH, and the average of two to three samples was calculated. The results are shown in Table 2 below.

[0121] (2) Dielectric breakdown strength The dielectric breakdown voltage (BDV) of the polyimide films prepared in the examples and comparative examples was measured according to ASTM D149 standard, and the average of eight samples was calculated. Specifically, the polyimide films were pretreated in an oven at 100°C to remove moisture, and then fixed in a measuring device (Phenix Technologies 6CCE50-5) set at room temperature. A voltage of 10 kVAc was applied to the electrodes, and the AC voltage was increased from 0 at a constant rate to measure the BDV. The results are shown in Table 4 below.

[0122] [Table 4] TIFF2025181709000009.tif38170

[0123] It was confirmed from Table 4 that the polyimide films according to Examples 25 to 48, which contained the triazine-based diamine in an appropriate content, all had good electrical properties.

[0124] Experimental Example 3: Evaluation of adhesive strength The polyimide varnishes prepared in Examples 1 to 24 and Comparative Examples 1 and 2 were cured to obtain cured products of Examples 25 to 48 and Comparative Examples 3 and 4, which were then examined for physical properties by the methods described below. The results are shown in Table 5 below.

[0125] (1) Peel Strength The polyimide varnishes prepared in the Examples and Comparative Examples were applied to copper foil (Cu foil), spin-coated, and cured to form a cured polyimide film on the copper foil (Cu foil). Peel strength was measured by peeling the copper foil (Cu foil) and cured polyimide layers using a UTM (Instron Model 5564) instrument. The cured polyimide layer (film layer) was secured to the upper grip and the copper foil (Cu foil) to the lower grip. Strength was measured by applying a force at a 90° peel angle and a peel rate of 50 mm / min under conditions of 23°C and 50% RH. The results are shown in Table 5 below.

[0126] (2) Adhesion (Crosscut Test) The adhesion strength of the polyimide films produced in the Examples and Comparative Examples was measured using the method prescribed in ASTM D 3359, and the results are shown in Table 5 below. Specifically, the polyimide films produced in the Examples and Comparative Examples were cut into a grid pattern with 1 mm intervals using a cutter, and then a peel test was conducted using special tape, and the degree of peeling was recorded. The fewer peeled areas, the higher the reliability as an insulator, and therefore the more preferable (5B: 0% of the total area removed; 4B: more than 0 to less than 5% of the total area removed; 3B: 5 to less than 15% of the total area removed; 2B: 15 to less than 35% of the total area removed; 1B: 35 to less than 65% of the total area removed).

[0127] [Table 5] TIFF2025181709000011.tif27170

[0128] Table 5 shows that the copper (Cu) adhesion of the polyimide films of Examples 26 to 28, 30 to 32, 34 to 36, 38 to 40, 42 to 44, and 46 to 48, which contained an appropriate amount of triazine-based diamine, was significantly improved. On the other hand, the adhesion (Crosscut Test) evaluation results of Comparative Examples 3 and 4, which did not contain triazine-based diamine, were 2B and 1B, respectively, which were somewhat lower.

[0129] Based on the results of Experimental Examples 1 to 3, it was found that the polyimide varnish of the present invention and the film containing the same contain a specific triazine-based diamine, which provides stable mechanical, thermal, and electrical properties and significantly improves adhesion to Cu. In particular, when obtaining a polyimide varnish that achieves these effects, improving one property generally results in a decrease in another property, and achieving various properties simultaneously is quite restrictive and complicated. Therefore, the present invention is technically significant in that it has discovered optimal monomer components and component ratios that are excellent in various properties.

[0130] This specification omits detailed descriptions of content that can be fully recognized and inferred by a person having ordinary skill in the art of the present invention, and various modifications are possible within the scope of the specific examples described herein without changing the technical idea or essential configuration of the present invention. Therefore, the present invention may be implemented in ways different from those specifically explained and exemplified in this specification, and this is something that can be understood by a person having ordinary skill in the art of the present invention.

Claims

1. containing a dianhydride monomer and a diamine monomer as polymerized units, the diamine monomer comprises a first diamine monomer and a second diamine monomer; The polyimide varnish, wherein the second diamine monomer is represented by the following chemical formula 1: 【Chemistry 1】 In chemical formula 1, A may be unsubstituted or substituted and is selected from the group consisting of hydrogen, halogen, C 1 -C 6 Alkyl, phenyl, (C 1 -C 6 alkylene)-(C 3 -C 5 Heteroaryl), (C 1 -C 6 alkylene)-COOH, or -OH, where the substitutions are halogen, C 1 -C 3 Alkyl, C 1 -C 3 Substitution to haloalkyl or oxo (=O).

2. The A is hydrogen, fluoro (F), chloro (Cl), bromo (Br), methyl, ethyl, propyl, phenyl, (C 1 -C 6 alkylene)-imidazolyl, (C 1 -C 6 alkylene)-COOH, or -OH; 2. The polyimide varnish according to claim 1, wherein A is unsubstituted or substituted with at least one of methyl, ethyl, trifluoromethyl, or oxo (=O).

3. 2. The polyimide varnish according to claim 1, wherein the carbon to nitrogen ratio (C / N) of the second diamine monomer is 0.5 to 2.

5.

4. The second diamine monomer is selected from the group consisting of 1,3,5-triazine-2,4-diamine, 6-chloro-1,3,5-triazine-2,4-diamine, 4,6-diamino-1,3,5-triazine-2-ol, 6-methyl-1,3,5-triazine-2,4-diamine, and 6-phenyl-1, 2. The polyimide varnish according to claim 1, comprising one or more compounds selected from the group consisting of 6-phenyl-1,3,5-triazine-2,4-diamine, 6-[2-(2-methylimidazolyl-1-yl)ethyl]-1,3,5-triazine-2,4-diamine, and 4-(4,6-diamino-1,3,5-triazin-2-yl)-4-oxobutanoic acid.

5. With respect to 100 mol% of the total content of the diamine monomers, The content of the primary diamine monomer is more than 90 mol% and 99.9 mol% or less, 2. The polyimide varnish according to claim 1, wherein the content of the secondary diamine monomer is 0.1 mol % or more and less than 10 mol %.

6. With respect to 100 mol% of the total content of the diamine monomers, the content of the primary diamine monomer is 90.5 mol% to 99 mol%, 2. The polyimide varnish according to claim 1, wherein the content of the secondary diamine monomer is 1 mol % to 9.5 mol %.

7. With respect to 100 mol% of the total content of the diamine monomers, the content of the primary diamine monomer is 91 mol% to 98 mol%, 2. The polyimide varnish according to claim 1, wherein the content of the secondary diamine monomer is 2 mol % to 9 mol %.

8. The polyimide varnish of claim 1 , wherein the dianhydride monomer comprises pyromellitic dianhydride (PMDA).

9. 2. The polyimide varnish according to claim 1, wherein the first diamine monomer comprises any one selected from the group consisting of 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), and mixtures thereof.

10. 10. The polyimide varnish according to claim 9, wherein the content of 4,4'-diaminodiphenyl ether (ODA) is 50 mol % or more relative to 100 mol % of the total content of the diamine monomers.

11. The polyimide varnish has a tensile strength of 100 MPa or more after curing; The modulus is 2.0 GPa or more, 2. The polyimide varnish according to claim 1, having an elongation of 8% or more.

12. The polyimide varnish has a glass transition temperature of 300°C or higher after curing, The temperature (Td) at which a weight loss of 1% occurs is 340°C or higher, The temperature (Td) at which a 5% weight loss occurs is 500°C or higher, 2. The polyimide varnish according to claim 1, which has a coefficient of thermal expansion (CTE) of 30 ppm / °C or more in the temperature range of 100°C to 350°C.

13. 2. The polyimide varnish according to claim 1, wherein the polyimide varnish has an adhesion of 3B or greater according to ASTM D 3359 after curing.

14. 2. The polyimide varnish according to claim 1, wherein the polyimide varnish has a peel strength of 3.0 N / cm or more after curing.

15. A cured polyimide product produced by curing the polyimide varnish according to any one of claims 1 to 14.

16. A polyimide coating comprising the polyimide cured product according to claim 15.

17. An electrical wire comprising the polyimide coating of claim 16.

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