Polyamic acid composition

Abstract

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

Description

Technical Field

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

Background Art

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

[0003] In addition, in an electrical device with a high application voltage, such as a motor used at a high voltage, a high voltage is applied to the insulated wire constituting the electrical device, and partial discharge (corona discharge) is likely to occur on the surface of the coating.

[0004] The occurrence of corona discharge causes local temperature rise and generation of ozone or ions. As a result, deterioration occurs in the insulating coating of the insulated wire, leading to early insulation breakdown and potentially shortening the life of the electrical device.

[0005] For insulated wires used at high voltages, improvement of the corona discharge inception voltage is required for the above reasons, and it is known that reducing the dielectric constant of the insulating layer is effective for this purpose.

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

[0007] Among these, polyimide resin in particular has excellent properties as a material for coating a conductor due to its excellent heat resistance and insulation properties.

[0008] Polyimide resin refers to a high heat-resistant resin produced by solution polymerization of an aromatic dianhydride and an aromatic diamine or aromatic diisocyanate to produce a polyamic acid derivative, followed by ring-closing dehydration at a high temperature for imidization.

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

[0010] However, although general polyimide resins have excellent physical properties, their storage stability decreases, and the adhesion to conductors is not excellent. Therefore, when forming an insulating coating, there may occur a problem that poor appearance is caused by a lifting phenomenon between the conductor and the coating.

[0011] Therefore, there is a demand for the production of a polyimide varnish for conductor coating that simultaneously satisfies storage stability, heat resistance, insulation, low dielectric constant, adhesion, and mechanical properties.

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[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 simultaneously satisfies flexibility, light resistance, heat resistance, insulation, adhesion, and mechanical properties at high temperature after curing.

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

[0015] [General formula 1] △V 23℃ =(V2 - V1) / V1×100

[0016] In the general formula 1, △V 23℃ represents the change rate of the viscosity (V2) of the polyamic acid composition stored for one week in a storage container sealed under the temperature condition of 23°C based on the viscosity (V1) of the polyamic acid composition before storage.

[0017] For example, the viscosity change rate at 23°C (△V 23℃ ) satisfies -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 viscosities (V1, V2) in the general formula 1 may be measured using Rheostress600 of Haake, or may be measured under the conditions of a shear rate of 1 / s, a temperature of 30°C, and a plate gap of 1 mm. The 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.

[0018] The polyamic acid composition according to the present application is excellent in storage stability at 23°C by satisfying the general formula 1.

[0019] The polyamic acid composition according to the present application satisfies a viscosity change rate at 30°C (△V 30℃ ) of -30% to +30%.

[0020] [General formula 2] △V 30℃ =(V4 - V3) / V3×100

[0021] In the general formula 2, △V 30℃ represents the change rate of the viscosity (V4) of the polyamic acid composition stored for one week in a storage container sealed under the temperature condition of 30°C based on the viscosity (V3) of the polyamic acid composition before storage.

[0022] For example, the viscosity change rate at 30°C (△V30℃ ) satisfies -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%.

[0023] The polyamic acid composition according to the present application is excellent in storage stability at 30°C by satisfying the general formula 2.

[0024] The viscosities (V3, V4) of the general formula 2 may be measured using Rheostress600 of Haake, or may be measured under the conditions of a shear rate of 1 / s, a temperature of 30°C, and a plate gap of 1 mm.

[0025] The polyamic acid composition according to the present application may further contain a modified monomer represented by the following chemical formula 1.

[0026] [Chemical formula]

[0027] In the chemical formula 1, A1 to A4 are each independently selected from a hydroxyl group (-OH), an amine group (-NH2), an alkoxy group, or an oxygen anion (-O - ), In the chemical formula 1, X is a tetravalent aliphatic ring group, a tetravalent heteroaliphatic ring group, a tetravalent aromatic ring group, or a tetravalent heteroaromatic ring group, and the carbon atom of the carbonyl group in the chemical formula 1 is linked to the ring-constituting atoms of the aliphatic ring group, heteroaliphatic ring group, aromatic ring group, or heteroaromatic ring group, The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group is a monocyclic ring, joined to each other to form a polycyclic ring, or It is linked by a linking group containing at least one divalent substituent 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.

[0028] Preferably, X in Chemical Formula 1 above is phenyl, biphenyl,

Chemical Formula

[0029] M contains at least one selected from the group consisting of a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O)2-.

[0030] The modified monomer represented by Chemical Formula 1 may be derived from a dianhydride monomer which is a polymerization unit of a polyamic acid. As the number of moles of the modified monomer increases, the elongation of the polyimide as the cured product tends to decrease. When coating a conductor, it is possible to induce the elongation to match that of the winding for coating the conductor by adjusting the number of moles of the modified monomer, thereby suppressing the lifting phenomenon between the winding and the coating.

[0031] In one example, the modified monomer represented by the chemical formula 1 may be included in the range of 6 to 15 mol% based on 100 mol% of the diamine monomer of the polyamic acid. The modified monomer may be in the 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% based on 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, improvement in elongation during curing, and excellent thermal stability, electrical properties and mechanical stability can be realized.

[0032] In another example, the molar ratio (A:B) of the dianhydride monomer (A) and the modified monomer (B) of the polyamic acid may be in the range of 1:0.06 to 1:0.15, 1:0.06 to 1:0.14, 1:0.06 to 1:0.13, 1:0.06 to 1:0.12, 1:0.06 to 1:0.11, 1:0.06 to 1:0.11, 1:0.06 to 1:0.1, 1:0.07 to 1:0.14, 1:0.07 to 1:0.13, 1:0.07 to 1:0.12, 1:0.07 to 1:0.11 or 1:0.07 to 1:0.1.

[0033] In one specific example, the dianhydride monomer which is a polymerization unit of the polyamic acid contains at least one compound represented by the following chemical formula 2.

[0034]

Chemical formula

[0035] In Chemical Formula 2, Y is a tetravalent aliphatic cyclic group, a tetravalent heteroaliphatic cyclic group, a tetravalent aromatic cyclic group, or a tetravalent heteroaromatic cyclic group, and the carbon atom of the carbonyl group in Chemical Formula 2 is linked to the ring-constituting atoms of the aliphatic cyclic group, heteroaliphatic cyclic group, aromatic cyclic group or heteroaromatic cyclic group. The aliphatic cyclic group, the heteroaliphatic cyclic group, the aromatic cyclic group or the heteroaromatic cyclic group is monocyclic, fused to each other to form a polycyclic ring, or linked by a linking group containing at least one divalent substituent 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(R a )2-, where R a is hydrogen or an alkyl group.

[0036] Preferably, Y in Chemical Formula 2 is phenyl, biphenyl,

Chemical formula

[0037] As used herein, the term "aliphatic cyclic group" may mean an aliphatic cyclic group having 3 to 30 carbon atoms, 4 to 25 carbon atoms, 5 to 20 carbon atoms, or 6 to 16 carbon atoms, unless otherwise specified. Specific examples of the tetravalent aliphatic cyclic group include, for example, groups obtained by removing 4 hydrogen atoms from rings such as cyclohexane ring, cycloheptane ring, cyclodecane ring, cyclododecane ring, norbornane ring, isobornane ring, adamantane ring, cyclododecane ring, dicyclopentane ring and the like.

[0038] As used herein, 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 otherwise specified. The aromatic ring may be a monocyclic ring or a condensed ring. Examples of the tetravalent aromatic hydrocarbon ring group include a group obtained by removing four hydrogen atoms from a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, or a pyrene ring.

[0039] As used herein, the term "arylene group" may mean a divalent organic group derived from the aromatic ring group.

[0040] As used herein, the term "heterocyclic group" includes a heteroaliphatic ring group and a heteroaromatic ring group.

[0041] As used herein, the term "heteroaliphatic ring group" may mean a ring group in which at least one of the carbon atoms of the aliphatic ring group is replaced by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus.

[0042] As used herein, the term "heteroaromatic ring group" may mean a ring group in which at least one of the carbon atoms of the aromatic ring is replaced by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus, unless otherwise specified. The heteroaromatic ring group may be a monocyclic ring or a condensed ring.

[0043] The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group may each independently be replaced by at least one substituent selected from the group consisting of a halogen, a hydroxy group, a carboxy group, an alkyl group having 1 to 4 carbon atoms which is substituted or unsubstituted with a halogen, and an alkoxy group having 1 to 4 carbon atoms.

[0044] As used herein, the term "single bond" may mean a bond connecting both atoms without any atoms. For example, X in Chemical Formula 1 or Y in Chemical Formula 2 is [Chemical] wherein when M is a single bond, the two aromatic rings may be directly linked to each other.

[0045] As used herein, 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 otherwise specified. The alkyl group may have a linear, branched or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include polar functional groups such as at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group or a thioether group.

[0046] As used herein, 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 otherwise specified. The alkenyl group may have a linear, branched or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include polar functional groups such as at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group or a thioether group.

[0047] As used herein, 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 otherwise specified. The alkynyl group may have a linear, branched or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include polar functional groups such as at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group or a thioether group.

[0048] As used herein, the term "alkylene group" shall, unless otherwise specified, 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. The alkylene group may have a linear, branched or cyclic structure as a divalent organic group from which two hydrogens are removed from different carbon atoms, and may optionally be replaced by at least one substituent. Examples of the substituent include polar functional groups such as at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0049] As used herein, the term "alkylidene group" shall, unless otherwise specified, 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. The alkylidene group may have a linear, branched or cyclic structure as a divalent organic group from which two hydrogens are removed from one carbon atom, and may optionally be replaced by at least one substituent. Examples of the substituent include polar functional groups such as at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0050] As used herein, the term "alkoxy group" shall, unless otherwise specified, 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. The alkoxy group may have an alkyl group with a linear, branched or cyclic structure, and the alkyl group may optionally be replaced by at least one substituent. Examples of the substituent include, for example, at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0051] As used herein, the term "alkylamine group" includes monoalkylamine (-NHR) or dialkylamine (-NR2) unless otherwise specified, where each 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. Here, the alkyl group may have a linear, branched, or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0052] As used herein, the term "alkylamide" includes monoalkylamide (-C(O)NHR) or dialkylamide (-C(O)NR2) unless otherwise specified, where each 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. Here, the alkyl group may have a linear, branched, or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0053] As used herein, the term "thioether group" or "sulfide" means -SR unless otherwise specified, where each 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. Here, the alkyl group may have a linear, branched, or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0054] As used herein, the term "sulfoxide" means -S(O)R, unless otherwise specified, where each R independently may be an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0055] As used herein, the term "carbonyl" includes -C(O)R, unless otherwise specified, where each R independently may be an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0056] As used herein, the term "ester" includes -C(O)OR or -OC(O)R, unless otherwise specified, where each R independently may be an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may optionally be replaced by at least one substituent. Examples of the substituent include at least one substituent consisting of a halogen, a hydroxy group, an alkoxy group, a thiol group, or a thioether group.

[0057] The aliphatic tetracarboxylic dianhydrides satisfying the chemical formula 2 are 1,2,4,5-cyclohexanetetracarboxylic dianhydride (or HPMDA), bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BODA), 1,2,3,4-cyclohexanetetracarboxylic dianhydride (CHMDA), bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BHDA), butane-1,2,3,4-tetracarboxylic dianhydride (BTD), bicyclo-[2.2.2]oct-7-ene-2-exo,3-exo,5-exo,6-exo-2,3:5,6-dianhydride (BTA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo[4.2.0]octane-3,4,7,8-tetracarboxylic dianhydride (OTD), norbornane-2-spiro-α-cyclohexanone-α’-spiro-2’’-norbornane-5,5’’,6,6’’-tetracarboxylic dianhydride (ChODA), cyclopentanone bis-spironorbornane 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-isobenzofurandione) (HODPA), 5,5’-methylenebis(hexahydro-1,3-isobenzofurandione) (HMDPA), 3,3’-(1,4-piperazinediyl)bis[dihydro-2,5-furandione] (PDSA), 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexane-1,2-dicarboxylic anhydride (DOCDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride (TDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-6-methyl-1-naphthalenesuccinic dianhydride (MTDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-6-fluoro-1-naphthalenesuccinic 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), 9,10-difluoro-9,10-bis(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetracarboxylic dianhydride (6FDA), etc.

[0058] The aromatic tetracarboxylic dianhydrides satisfying the above Chemical Formula 2 include pyromellitic dianhydride (or PMDA), 3,3’,4,4’-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3’,4’-biphenyltetracarboxylic dianhydride (or a-BPDA), oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3’,4’-tetracarboxylic dianhydride (or DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3’,4’-benzophenonetetracarboxylic dianhydride, 3,3,3’,4’-benzophenonetetracarboxylic dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimellitic monoester anhydride), p-biphenylenebis(trimellitic monoester anhydride), m-terphenyl-3,4,3’,4’-tetracarboxylic dianhydride, p-terphenyl-3,4,3’,4’-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4’-(2,2-hexafluoroisopropylidene)diphthalic dianhydride (6-FDA), and the like.

[0059] In one specific example, the dianhydride monomer may preferably be at least one selected from aromatic tetracarboxylic dianhydrides such as PDMA, BPDA, a-BPDA, ODPA, DSDA, or BTDA.

[0060] In one specific example, the diamine monomer may contain at least one or more compounds represented by the following Chemical Formula 3.

[0061] [Chem.]

[0062] In the chemical formula 3, any one of B1 to B5 is an amino group, and the rest represent hydrogen, halogen, hydroxy group, carboxyl group, or an alkyl group substituted or unsubstituted with halogen.

[0063] As an example, the diamine monomer is an aromatic diamine, and examples can be given by classification as follows.

[0064] 1) Diamines having one benzene nucleus in structure and relatively rigid structures, such as 1,4-diaminobenzene (or paraphenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, or 3,5-diaminobenzoic acid (or DABA).

[0065] 2) Diamines having two benzene nuclei in structure, 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'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 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,

[0066] 3) Diamines having three benzene nuclei in structure, such as 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, 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,

[0067] 4) Diamines having four benzene nuclei in structure, such as 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]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(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.

[0068] The diamine monomer may be used alone or in combination of two or more as necessary. In the present application, two or more diamine monomers having different structural characteristics are considered in view of the bond dissociation energy. For example, a diamine having one benzene nucleus in structure and a diamine having at least two benzene nuclei in structure may be used in combination.

[0069] In one specific example, the diamine monomer may contain 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). For example, it may contain 1,4-diaminobenzene (PPD) and 4,4'-diaminodiphenyl ether (or oxydianiline, ODA).

[0070] In one specific example, the polyamic acid composition may have a solid content of 5 to 40% by weight, 5 to 35% by weight, 10 to 40% by weight, 10 to 35% by weight, 10 to 30% by weight, 15 to 40% by weight, or 15 to 35% by weight based on the total weight, and preferably may contain 15 to 30% by weight. In the present application, by adjusting the content of the solid content of the polyamic acid composition, it is possible to prevent an increase in the manufacturing cost and process time that must remove a large amount of solvent during the curing process while controlling the increase in viscosity.

[0071] In one specific example, 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 means the conversion numerical value with respect to standard polystyrene measured by GPC (Gel permeation Chromatograph).

[0072] In this application, based on the total solid content, the polyamic acid may be in the range of 1 to 50% by weight, 1 to 45% by weight, 1 to 40% by weight, 1 to 30% by weight, 5 to 50% by weight, 5 to 45% by weight, 5 to 40% by weight, 5 to 30% by weight, 5 to 25% by weight, 5 to 20% by weight, 10 to 20% by weight, or 15 to 20% by weight.

[0073] The polyamic acid composition of this application may have low viscosity characteristics. The polyamic acid composition of this application has a viscosity measured under the conditions of a temperature of 23 °C and a shear rate of 1 s -1 which may be 50,000 cP or less, 40,000 cP, 30,000 cP, 20,000 cP, 10,000 cP or less, 9,000 cP or less. The lower limit is not particularly 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 Rheostress600 from Haake, or may be measured under the conditions of a shear rate of 1 / s, a temperature of 23 °C, and a plate gap of 1 mm. This application can provide a polyamic acid composition with excellent processability and product applicability by adjusting the viscosity range.

[0074] In this application, the polyamic acid composition may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the polyamic acid, and as an example, it may be an aprotic polar solvent.

[0075] Examples of the aprotic polar solvent include amide solvents such as N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), or dimethylpropionamide (DMPA), phenolic solvents such as p-chlorophenol or o-chlorophenol, N-methyl-pyrrolidone (NMP), γ-butyrolactone (GBL), or diglyme (Diglyme), etc. These may be used alone or in combination of two or more.

[0076] In this application, auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, or water may be used as appropriate to adjust the solubility of the polyamic acid.

[0077] In one example, the organic solvent may be, for example, N-methyl-pyrrolidone (NMP).

[0078] The polyamic acid may be formed by a polymerization reaction of a diamine monomer and a dianhydride monomer in an inert atmosphere and within a temperature range of 20 to 60°C.

[0079] This application further relates to a polyimide which is a cured product of the polyamic acid composition described above. By curing the polyamic acid composition described above, the polyimide can simultaneously satisfy flexibility, light resistance, heat resistance, insulation, adhesion, and mechanical properties at high temperatures.

[0080] The polyimide may be formed by thermal curing of the polyamic acid. The thermal curing may be carried out, for example, within a temperature range of 100 to 600°C.

[0081] The polyimide can have various physical property controls within the following numerical ranges by adjusting the materials and content ratios of the polyamic acid composition described above.

[0082] Hereinafter, the measurement of physical properties may be performed after preparing a film-shaped sample having a thickness of 10 to 30 μm of the polyimide.

[0083] For example, the elongation of the polyimide measured using a UTM (Universal Testing Machine) device may be within 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.

[0084] The polyimide may have a tensile strength of 500 Mpa or less, measured using a UTM (Universal Testing Machine) device. For example, it may be 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. 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 measurement may be performed using a UTM device under the conditions of a width of 20 mm, a grip distance of 50 mm, and a crosshead speed of 20 mm / min.

[0085] In addition, the polyimide may have a coefficient of thermal expansion (CTE) measured using a TMA (Thermo Mechanical Analysis) device within the range of 0.1 ppm / °C to 50 ppm / °C, 0.5 ppm / °C to 50 ppm / °C, 1 ppm / °C to 50 ppm / °C, 5 ppm / °C to 50 ppm / °C, 10 ppm / °C to 45 ppm / °C, 15 ppm / °C to 40 ppm / °C, 20 ppm / °C to 40 ppm / °C, 25 ppm / °C to 40 ppm / °C, or 25 ppm / °C to 35 ppm / °C. The measurement may be performed using a TMA device while applying a load of 0.02 N in the temperature range of 50 to 200 °C at a heating rate of 10 °C / min.

[0086] The polyimide may have a glass transition temperature measured using a DMA (Dynamic Mechanical Analysis) apparatus within the range of 200 to 500 °C, 250 to 450 °C, 300 to 400 °C, or 350 to 400 °C. The measurement may be performed using a DMA apparatus at a heating rate of 5 °C / min.

[0087] And the 5% thermal decomposition temperature of the polyimide measured using a TGA (Thermo Gravimetric Analysis) apparatus 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 at a temperature of 150 °C and then using a TGA apparatus at a heating rate of 10 °C / min for 30 minutes.

[0088] Also, the polyimide may have a dielectric constant (Dk) measured according to ASTM D150 within 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.

[0089] The polyimide may have a breakdown voltage (BDV) measured according to ASTM D149 within 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 breakdown voltage may be measured by a method known in the same industry. In one example, the breakdown voltage may be measured as follows. The polyimide is made into a film-like specimen, and all the moisture in the film is removed in an oven at 100 °C or below. Then, after cutting the specimen into an appropriate size, an insulating breakdown measuring instrument (Automated Test Set for Insulating Materials, equipment suitable for ASTM D149 standard, PHENIX TECHNOLOGIES 6CCE50-5) is utilized. After placing the specimen on the sample stage, the voltage is increased from 0 at a constant rate, and the limiting insulation endurance of the insulator is measured.

[0090] Further, this application relates to a coating. The coating may include a polyimide which is a cured product of the polyamic acid composition described above. The coating may include a substrate and a polyimide coated on the substrate. The polyimide may be coated and cured, for example, on the surface of a conductor.

[0091] The substrate may be a conductor. The conductor may be a copper wire made of copper or a copper alloy, but conductors made of other metal materials such as silver wires, and various metal-coated wires such as aluminum and tin-coated wires may also be included as conductors. The thicknesses of the conductor and the coating comply with the KS C 3107 standard. The diameter of the conductor may be in the range of 0.3 to 3.2 mm, and the standard coating thickness (average value of the maximum coating thickness and the minimum coating thickness) of the coating 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 loop wire, a flat wire, a hexagonal wire, etc., but is not limited thereto.

[0092] In one example, the coating may include a step of coating a polyamic acid composition on the surface of a conductor and a step of imidizing the polyamic acid composition coated on the surface of the conductor.

[0093] The present invention can further provide an electronic device including the coating.

Effects of the Invention

[0094] This application provides a polyamic acid composition having excellent storage stability and capable of simultaneously realizing a low dielectric constant, heat resistance, insulation properties, and mechanical properties under severe conditions such as high temperature, a polyimide which is a cured product of the composition, a coating including the polyimide, a coated electric wire including the coating, and an electronic device including the coated electric wire.

Modes for Carrying Out the Invention

[0095] Hereinafter, the present invention will be described in more detail through examples according to the present invention and comparative examples not according to the present invention. However, the scope of the present invention is not limited by the following examples.

Example

[0096] <Example 1> Production of polyamic acid composition While injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge pipe, N-methyl-pyrrolidone (NMP) was charged. After setting the temperature of the reactor to 40°C, 4,4'-diaminodiphenyl ether (oxydianiline, ODA), pyromellitic dianhydride (PMDA), and modified pyromellitic dianhydride (PMDA*) were charged and confirmed to be completely dissolved. Next, 1,4-diaminobenzene (or paraphenylenediamine, PPD) was charged, and a polyamic acid composition was produced by performing a polymerization reaction in the same manner.

[0097] The modified pyromellitic dianhydride (PMDA*) described above is represented by the following Chemical Formula 4.

[0098]

Chemical formula

[0099] Production of polyimide film The polyamic acid composition was sequentially cured at 100°C for 20 minutes, 150°C for 20 minutes, 200°C for 20 minutes, 300°C for 20 minutes, 350°C for 20 minutes, and 110°C for 60 minutes to produce a polyimide film with a thickness of 30 μm.

[0100] <Examples 2 to 4 and Comparative Examples 1 to 2> In Example 1, polyamic acid compositions and polyimide films of Examples 2 to 4 and Comparative Examples 1 to 2 were produced in the same manner as in Example 1, except that the monomers and their content ratios were changed as shown in Table 1 below.

[0101]

Table 1

[0102] <Experimental Example 1 - Viscosity change rate at 23°C and 30°C> The polyamic acid compositions of the examples and comparative examples were stored for one week in a sealed storage container under temperature conditions of 23°C and 30°C, and the viscosity change rates before and after storage were measured respectively. The results are shown in Table 2 below.

[0103] The viscosities before and after the storage were measured using a Rheostress600 from Haake at a shear rate of 1 / s, a temperature of 23°C (or 30°C), and a 1 mm plate gap condition.

[0104] <Experimental Example 2 - Elongation, tensile strength, and modulus> The elongation, tensile strength, and modulus of the polyimide films produced in the examples and comparative examples were measured using a UTM (Universal Testing Machine) device respectively. The results are shown in Table 2 below.

[0105] <Experimental Example 3 - Glass transition temperature> The glass transition temperatures of the polyimide films produced in the examples and comparative examples were measured using a DMA (Dynamic mechanical analysis) device. The results are shown in Table 2 below.

[0106] <Experimental Example 4 - 5% Thermal decomposition temperature> The 5% thermal decomposition temperatures of the polyimide films produced in the examples and comparative examples were measured using a TGA (Thermo Gravimetric analysis) device. The results are shown in Table 2 below.

[0107] <Experimental Example 5 - Coefficient of thermal expansion (CTE)> The coefficients of thermal expansion of the polyimide films produced in the examples and comparative examples were measured using a TMA (Thermo Mechanical Analysis) device. The results are shown in Table 2 below.

[0108] <Experimental Example 6 - Dielectric constant> The dielectric constants of the polyimide films produced in the examples and comparative examples were measured according to ASTM D150, and the results are shown in Table 2 below.

[0109] <Experimental Example 7 - Dielectric Breakdown Voltage> The polyimide films produced in the examples and comparative examples were used as specimens, and all the moisture in the films was removed in an oven at 100 °C or lower. After that, after cutting the specimens into appropriate sizes, an insulating breakdown measuring instrument (Automated Test Set for Insulating Materials, equipment suitable for ASTM D149 standard, PHENIX TECHNOLOGIES 6CCE50 - 5) was utilized. After placing the specimens on the sample stage, the voltage was increased from 0 at a constant rate, and the limiting dielectric strength of the insulator was measured, and the results are shown in Table 2 below.

[0110]

Table 2

[0111] As confirmed from Table 2 above, Comparative Example 1 is a sample containing relatively few modified monomers compared to the examples. The 23 °C viscosity change rate value and the 30 °C viscosity change rate value are 28% and 51% respectively, showing results exceeding the upper limits of 25% and 30%. Also, although the molar ratio of diamine to dianhydride is close to 1:1, the modified monomers are not sufficiently contained, and the desired storage stability cannot be ensured, showing results where the viscosity change rate value exceeds the upper limit value.

[0112] Moreover, Comparative Example 2 is a sample that does not contain modified monomers. The 23 °C viscosity change rate value and the 30 °C viscosity change rate value are 35% and 80% respectively, showing results exceeding the upper limits of 25% and 30%. The molar ratio of diamine to dianhydride is 100:95, which is lower than the general mixing ratio of 1:1 and has a low molecular weight, so a film was not formed and other physical properties could not be measured.

Claims

1. A polyamic acid having diamine monomers and dianhydride monomers as polymerization units, The polyamic acid composition in which the viscosity change rate (ΔV ２３℃ at 23°C) of the following general formula (1) satisfies -25% to +25%: [General Formula 1] △V ２３℃ = (V2 - V1) / V1 × 100 In the general formula (1), ΔV ２３℃ represents the change rate of the viscosity (V2) of the polyamic acid composition stored for one week in a storage container sealed under temperature conditions of 23°C, based on the viscosity (V1) of the polyamic acid composition before storage.

2. The 30°C viscosity change rate (ΔV ３０℃ ) of the following general formula (2) satisfies -30% to +30%, and the polyamic acid composition according to claim 1: [General Formula 2] △V ３０℃ = (V4 - V3) / V3 × 100 In the general formula (2), ΔV ３０℃ represents the change rate of the viscosity (V4) of the polyamic acid composition stored for one week in a storage container sealed under temperature conditions of 30°C, based on the viscosity (V3) of the polyamic acid composition before storage.

3. The polyamic acid composition according to claim 1, further comprising a modified monomer represented by the following Chemical Formula 1: 【Chemical 1】 In the chemical formula 1, A １ ~A ４ are each independently selected from a hydroxyl group (-OH), an amine group (-NH ２ ), an alkoxy group or an oxygen anion (-O － ), In the Chemical Formula 1, X is a tetravalent aliphatic ring group, a tetravalent heteroaliphatic ring group, a tetravalent aromatic ring group, or a tetravalent heteroaromatic ring group, and the carbon atom of the carbonyl group in Chemical Formula 1 is linked to the ring-constituting atoms of the aliphatic ring group, heteroaliphatic ring group, aromatic ring group or heteroaromatic ring group, The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group or the heteroaromatic ring group is a monocyclic ring, is bonded to each other to form a polycyclic ring, or A linking group containing at least one divalent substituent 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(R ａ ), ２ linked by a linking group containing at least one divalent substituent 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) ａ wherein R is hydrogen or an alkyl group.

4. The polyamic acid composition according to claim 3, wherein the modified monomer represented by the Chemical Formula 1 is contained in a range of 6 to 15 mol% based on 100 mol% of the diamine monomer of the polyamic acid.

5. The polyamic acid composition according to claim 1, wherein the dianhydride monomer contains at least one compound represented by the following Chemical Formula 2: [Chemical 2] In the Chemical Formula 2, Y is a tetravalent aliphatic ring group, a tetravalent heteroaliphatic ring group, a tetravalent aromatic ring group, or a tetravalent heteroaromatic ring group, and the carbon atom of the carbonyl group in Chemical Formula 2 is linked to the ring-constituting atoms of the aliphatic ring group, heteroaliphatic ring group, aromatic ring group or heteroaromatic ring group, and the aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group or the heteroaromatic ring group is a monocyclic ring, is joined to each other to form a polycyclic ring, or A linking group containing at least one divalent substituent 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(R ａ ), ２ and is linked by a linking group containing at least one divalent substituent 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) ａ wherein R is hydrogen or an alkyl group.

6. The polyamic acid composition according to claim 1, wherein the diamine monomer contains at least one compound represented by the following Chemical Formula 3: 【Chemical Formula 3】 In the above Chemical Formula 3, B １ ~B ５ is any one of amino groups, and the rest represent hydrogen, halogen, hydroxy group, carboxyl group, or an alkyl group which is substituted or unsubstituted by halogen.

7. The polyamic acid composition according to claim 3, wherein the molar ratio (A:B) of the dianhydride monomer (A) to the modified monomer (B) of the polyamic acid is in the range of 1:0.06 to 1:0.

15.

8. The polyamic acid composition according to claim 1, wherein the solid content is in the range of 5 to 40% by weight.

9. The viscosity measured under the conditions of a temperature of 30°C and a shear rate of 1 s －１ is within the range of 1,000 to 50,000 cp, and the polyamic acid composition according to claim 1.

10. A polyimide which is a cured product of the polyamic acid composition according to claim 1.

11. The polyimide according to claim 10, wherein the elongation measured using a UTM (Universal Testing Machine) apparatus is in the range of 10% to 60%.

12. The polyimide according to claim 10, wherein the coefficient of thermal expansion (CTE) measured using a TMA (Thermo Mechanical Analysis) apparatus is in the range of 0.1 ppm / °C to 50 ppm / °C.

13. The polyimide according to claim 10, wherein the glass transition temperature measured using a DMA (Dynamic mechanical analysis) apparatus is in the range of 200 to 500 °C.

14. The polyimide according to claim 10, wherein the 5% thermal decomposition temperature measured using a TGA (Thermo Gravimetric Analysis) apparatus is in the range of 450 to 650 °C.

15. The polyimide according to claim 10, wherein the dielectric constant (Dk) measured according to ASTM D150 is in the range of 1 to 5.

16. The polyimide according to claim 10, wherein the breakdown voltage (BDV) measured according to ASTM D149 is in the range of 100 to 500 kV / mm.

17. A substrate, A coating, comprising the polyimide according to any one of claims 10 to 16 coated on the substrate.

18. The coating according to claim 17, wherein the substrate is a conductor.

19. An electronic device, comprising the coating according to claim 17.

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