TWI846051B - Polyamic acid composition and polyimide prepared therefrom - Google Patents

Abstract

The present invention relates to a polyamic acid composition and a polyimide prepared therefrom, which has high transparency and excellent electrical conductivity.

Description

Polyamic acid composition and polyimide prepared therefrom

The present invention relates to a polyamic acid composition and a polyimide prepared therefrom.

Generally speaking, polyimide (PI) resin refers to a high heat-resistant resin made by preparing a polyamide derivative by solution polymerization of aromatic dianhydride and aromatic diamine or aromatic diisocyanate, and then curing it through imidization. Polyimide is a heat-stable polymer material based on a rigid aromatic main chain. Based on the chemical stability of the imide ring, it has excellent mechanical properties such as strength, chemical resistance, weather resistance and heat resistance. In addition, polyimide has attracted much attention as a high-functional polymer material that can be applied to a wide range of industrial fields such as electronics, communications, and optics due to its excellent electrical properties such as insulation properties and low dielectric constant. In recent years, with the thinning, lightening and miniaturization of various electronic devices, many studies have been conducted to impart conductivity to lightweight, highly flexible and heat-resistant polyimide as a component of electronic devices. As a method for imparting conductivity to polyimide, a method of dispersing a carbon-based conductive material in a polyimide precursor is known. However, the polyimide obtained by curing the polyimide precursor in which the carbon-based conductive material is dispersed has a low transmittance and is therefore not suitable for fields requiring transparency such as the display industry. There is also a disadvantage that an excessive amount of conductive material is required.

Problem to be solved by the invention The purpose of the present invention is to provide a polyamide composition and a polyimide film having high transparency and low surface resistance. Technical means for solving the problem The polyimide resin is prepared by preparing a polyamide derivative by polymerization of aromatic dianhydride and aromatic diamine or aromatic diisocyanate, and then curing and imidization. Polyimide is based on a rigid aromatic main chain and therefore has excellent thermal stability. However, in contrast to the high thermal stability brought about by the aromatic main chain, the transparency is greatly reduced, and therefore, the use in the field of electronic materials, especially in the field of displays requiring high transparency, is limited. In particular, research has recently been conducted on imparting conductivity to polyimide for application in the field of the electronics industry, but it is more difficult to improve the transparency of polyimide added with conductive materials. The polyamic acid composition according to the present invention can provide a polyimide having high transmittance and excellent conductivity by including a polymer containing a dianhydride monomer and a diamine monomer as polymerization units and a conjugated conductive polymer with excellent compatibility in the polyamic acid composition. In addition, in the polyamic acid composition according to the present invention, the conjugated conductive polymer has an excellent effect on the solvent, so the dispersibility of the conjugated conductive polymer is excellent, and the polyimide prepared by curing the conjugated conductive polymer contains a small amount of the conjugated conductive polymer and has excellent conductivity. In particular, the polyamic acid composition according to the present invention has high transparency and conductivity as described above, and also maintains excellent thermal and mechanical properties unique to polyimide. The present invention relates to a polyamine composition. The polyamine composition comprises a polymer having polymer units derived from a dianhydride monomer and a diamine monomer and a conjugated conductive polymer. The conjugated conductive polymer is generally referred to as a polymer having a structure in which multiple bonds are formed by atomic valence electrons with a single bond as the center. Specifically, the conjugated conductive polymer can be a polymer having a chemical structure in which double bonds and single bonds or triple bonds and single bonds are alternately connected. Examples of the conjugated conductive polymer according to the present invention may include polyfluorene, polyphenylene, polypyrene, polyazulene, polynaphthalene, polyacetylene, polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene sulfide), polypyrrole, polycarbazole, polyindole, polyazepine or polyaniline. When the dianhydride monomer and the diamine monomer of the polymerized unit constituting the polymer of the polyamic acid composition according to the present invention include an aromatic dianhydride monomer and/or an aromatic diamine monomer, the conjugated conductive polymer may include an aromatic ring or a heteroatom from the viewpoint of compatibility. Examples of the above-mentioned conjugated conductive polymer include at least one selected from the group consisting of polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene sulfide), polypyrrole, polycarbazole, polyindole, polyazepine and polyaniline. In addition, the polymer including the dianhydride monomer and the diamine monomer of the polyamide composition according to the present invention includes nitrogen atoms. Therefore, from the viewpoint of dispersibility and compatibility, the impurity atom of the above-mentioned conjugated conductive polymer is preferably nitrogen. Therefore, the conjugated conductive polymer according to the present invention can be at least one selected from the group consisting of polypyrrole, polycarbazole, polyindole, polyazepine and polyaniline. In particular, from the viewpoint of improving the transparency of the cured polyimide, low molecular weight polypyrrole containing nitrogen atoms in the aromatic ring is preferred. The film conductivity (Dried Cast Film Conductivity, Dried Cast Film) of the conjugated conductive polymer according to the present invention is The conductivity of the conjugated conductive polymer may be 0.005 S/cm or more. For example, the membrane conductivity of the conjugated conductive polymer may be 0.006 S/cm or more, 0.007 S/cm or more, 0.008 S/cm or more, 0.009 S/cm or more, or 0.01 S/cm or more. When the membrane conductivity of the conjugated conductive polymer satisfies the membrane conductivity as described above, the polyamine composition containing the conjugated conductive polymer may have improved conductivity. At this time, the content of the conjugated conductive polymer may be 0.01 wt % to 1 wt % based on the total weight of the polyamine composition. Specifically, the content of the conjugated conductive polymer may be 0.05 wt % to 1 wt %, 0.05 wt % to 0.9 wt %, 0.1 wt % to 1 wt %, 0.1 wt % to 0.7 wt %, 0.2 wt % to 1 wt %, 0.2 wt % to 0.9 wt %, 0.2 wt % to 0.7 wt %, 0.3 wt % to 1 wt %, 0.3 wt % to 0.9 wt %, 0.3 wt % to 0.7 wt %, 0.4 wt % to 0.7 wt % or 0.4 wt % to 0.6 wt %. When the polyamide composition according to the present invention contains the conjugated conductive polymer in the above content, it has excellent transparency and excellent conductivity. The surface resistance of the polyamide composition according to the present invention measured according to ASTM D257 after curing may be 1.0×10 ¹³ Ω/□ or less. In addition, the average light transmittance of the polyamine composition of the present invention at a thickness of 10 μm at a wavelength of 380 nm to 780 nm after curing can be more than 50%. The specific measurement methods and measurement conditions of the various physical properties recorded in the present invention are described in detail in the experimental examples described below. Specifically, the average light transmittance of the polyamine composition of the present invention at a thickness of 10 μm at a wavelength of 380 nm to 780 nm after curing can be more than 50%. For example, the above-mentioned light transmittance can be more than 52%, more than 54%, more than 56%, more than 58%, more than 60%, more than 62%, more than 64%, more than 66%, more than 68%, more than 70%, more than 75%, more than 80%, more than 82%, more than 84%, or more than 85%, and its upper limit is not particularly limited and can be less than 90%. The light transmittance can be measured using a UV-Vis spectrophotometer. In addition, the surface resistance of the polyamine composition according to the present invention measured in accordance with ASTM D257 can be 1.0×10 ¹³ Ω/□ or less. For example, the surface resistance may be 6.0×10 ¹² Ω/□ or less, 2.0×10 ¹² Ω/□ or less, 5.0×10 ¹¹ Ω/□ or less, or 2.0×10 ¹¹ Ω/□ or less. Specifically, the surface resistance may be 1.0×10 ¹¹ to 1.0×10 ¹³ Ω/□, 1.0×10 ¹¹ to 6.0×10 ¹² Ω/□, 1.0×10 ¹¹ to 2.0×10 ¹² Ω/□, or 1.0×10 ¹¹ to 1.0×10 ¹² Ω/□. The present invention can provide a polyamide composition having high transparency and excellent conductivity by satisfying the above-mentioned transmittance and surface resistance at the same time. The dianhydride monomer that can be used to prepare the polyamide solution can be an aromatic tetracarboxylic dianhydride. Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or a-BPDA), oxyphthalic 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',4,4'-benzophenonetetracarboxylic dianhydride (or BTDA), bis(3,4 -dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis(trimellitic acid monoester anhydride), p-biphenylene bis(trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1, 4-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic anhydride, 1,4,5,8-naphthalenetetracarboxylic anhydride or 4,4'-(2,2-hexafluoroisopropylidene)diphthalic anhydride, etc. As required, the above-mentioned dianhydride monomers can be used alone or in combination of two or more, for example, they can include at least one selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), oxyphthalic dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)phthalic anhydride (6-FDA) and p-phenylenebis(trimellitic anhydride) (TAHQ). In one embodiment of the present invention, the above-mentioned dianhydride monomers can include dianhydride monomers having one benzene ring and dianhydride monomers having two or more benzene rings. The above-mentioned dianhydride monomer having one benzene ring and the above-mentioned dianhydride monomer having two or more benzene rings can be contained in a molar ratio of 20 mol% to 60 mol% and 40 mol% to 90 mol%; 25 mol% to 55 mol% and 45 mol% to 80 mol%; or 35 mol% to 53 mol% and 48 mol% to 75 mol%. In the present invention, by containing the above-mentioned dianhydride monomer, the desired level of mechanical properties can be achieved while having excellent adhesion. In addition, the diamine monomer that can be used to prepare the polyamide solution is an aromatic diamine, which can be classified as follows and illustrated by examples. 1) A diamine having a benzene nucleus in the structure, such as 1,4-diaminobenzene (or p-phenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene or 3,5-diaminobenzoic acid (or DABA); 2) A diamine having a relatively rigid structure, such as 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-benzidine), 2,2'-dimethylbenzidine (or m-toluidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3, 4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether (or oxydiphenylamine, ODA), 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3 diamines having two benzene nuclei in their structure, such as 2,4'-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'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone or 4,4'-diaminodiphenylsulfone; 3) such as 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-amino)phenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (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' - diamines having three benzene nuclei in the structure, such as bis(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylene sulfide)benzene, 1,3-bis(4-aminophenylene sulfide)benzene, 1,4-bis(4-aminophenylene sulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenylsulfone)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene or 1,4-bis[2-(4-aminophenyl)isopropyl]benzene; 4) 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)c y) 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] sulfide, bis[4-(4-aminophenoxy)phenyl] sulfide, bis[3-(3-aminophenoxy)phenyl] sulfide, bis[3-(4-aminophenoxy)phenyl] sulfide, bis[4-(3-aminophenoxy)phenyl] sulfide, 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, )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 or 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane. In one example, the diamine monomer according to the present invention may include a monomer selected from 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4-diaminobenzanilide (4,4-DABA), N,N-bis(4-aminophenyl)benzene-1,4 At least one of the group consisting of trifluoromethylbenzidine (TPE-Q), 2,2-dimethylbenzidine (TOLIDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-bisaminophenoxybenzene (TPE-R), 2,2-bisaminophenoxyphenylpropane (BAPP) and 2,2-bisaminophenoxyphenylhexafluoropropane (HFBAPP). The polyamine composition according to the present invention includes a solvent, and the solvent may be an organic solvent. The solvent having good compatibility with the polyimide precursor may be at least one selected from the group consisting of N,N-diethylacetamide (DEAC), N,N-dimethylpropionamide (DMPA), 3-methoxy-N,N-dimethylpropionamide (KJCMPA), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL) and diglyme. Specifically, from the viewpoint of the dispersibility of the conjugated conductive polymer according to the present invention, it is preferably at least one selected from the group consisting of N,N-diethylacetamide (DEAC), N,N-dimethylpropionamide (DMPA) and N-methyl-2-pyrrolidone (NMP). N,N-diethylacetamide (DEAC) or N,N-dimethylpropionamide (DMPA) has a weak polarity, so when any one of these is used alone or the mixing amount thereof is increased, the dispersibility of the conjugated conductive polymer can be improved. In particular, when N-methyl-2-pyrrolidone (NMP) having a ring and N,N-diethylacetamide (DEAC) or N,N-dimethylpropionamide (DMPA) having a relatively weak polarity are mixed, the dispersibility of the conjugated conductive polymer is improved, thereby improving the conductivity and transparency. At this time, the molar ratio of N-methyl-2-pyrrolidone (NMP) and N,N-diethylacetamide (DEAC) or N,N-dimethylpropionamide (DMPA) relative to the total solvent can be 3:7 to 7:3, for example, the molar ratio of the above-mentioned N-methyl-2-pyrrolidone (NMP) and N,N-diethylacetamide (DEAC) or N,N-dimethylpropionamide (DMPA) can be 6:4 to 4:6 or 4.5:5.5 to 5.5:4.5. In addition, the boiling point of the solvent of the polyamine composition of the present invention can be above 150°C. For example, the boiling point of the solvent of the polyamine composition can be above 160°C or above 170°C. Specifically, the lower limit of the boiling point of the above-mentioned solvent can be, for example, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C or 201°C, and the upper limit can be, for example, 500°C, 450°C, 300°C, 280°C, 270°C, 250°C, 240°C, 230°C, 220°C, 210°C or 205°C or less. By having such a boiling point, water and solvent can be easily separated during curing. On the other hand, in order to improve various properties of the film such as slip, thermal conductivity, electrical conductivity, corona resistance, ring hardness, etc., the polyamide composition of the present invention can include a filler. The added filler is not particularly limited, for example, silicon dioxide, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, etc. can be cited. The particle size of the above filler is not particularly limited, and may depend on the characteristics of the modified film and the type of added filler. The above average particle size may be 0.05μm to 20μm, 0.1μm to 10μm, 0.1μm to 5μm or 0.1μm to 3μm. In this specification, unless otherwise specified, the average particle size may be the average particle size measured according to the D50 particle size analysis. In the present invention, by adjusting the above particle size range, the modification effect can be fully maintained without damaging the surface characteristics and reducing the mechanical properties. In addition, in the present invention, the amount of filler added is not particularly limited, and may depend on the modified film characteristics, filler particle size, etc. In the present invention, based on 100 parts by weight of the composition, the addition amount of the above-mentioned filler can be 0.01 to 10 parts by weight, 0.01 to 5 parts by weight or 0.02 to 1 part by weight. In the present invention, by adjusting the above-mentioned content, the modification effect can be fully maintained without reducing the mechanical properties of the film. The method of adding the above-mentioned filler is not particularly limited, and methods known in the art can be used. The solid content of the polyamine composition according to the present invention can be 5% by weight to 30% by weight. The above-mentioned solid content can be more than 7% by weight, more than 9% by weight, more than 10% by weight, more than 13% by weight, more than 15% by weight, more than 17% by weight, and the upper limit can be, for example, less than 30% by weight, less than 26% by weight, less than 24% by weight, less than 20% by weight or less than 19% by weight. The present invention controls the viscosity increase while maintaining the physical properties after curing at a desired level by adjusting the solid content of the above-mentioned polyamine composition at a higher level, and prevents the increase in manufacturing costs and process time required to remove a large amount of solvent during the curing process. In addition, the present invention provides a method for preparing a polyamine composition. The method for preparing the polyamine composition according to the present invention includes the steps of polymerizing a dianhydride monomer and a diamine monomer. As the polymerization method of the above-mentioned dianhydride monomer and diamine monomer, an existing polyimide precursor polymerization method such as solution polymerization can be used. For example, examples of the above method include: (1) a method in which the entire amount of diamine monomer is placed in a solvent, and then a dianhydride monomer is added in a substantially equimolar ratio to the diamine monomer to carry out polymerization; (2) a method in which the entire amount of dianhydride monomer is placed in a solvent, and then a diamine monomer is added in a substantially equimolar ratio to the dianhydride monomer to carry out polymerization; (3) a method in which a portion of the diamine monomer is placed in a solvent, a portion of the dianhydride monomer is mixed with the reaction components, and then the remaining diamine monomer is added, and the remaining dianhydride monomer is continuously added to make the diamine monomer and the dianhydride monomer substantially equimolar; (4) After the dianhydride monomer is placed in a solvent, a portion of the diamine monomer is mixed with the reaction components, and then other dianhydride monomer components are added, and the remaining diamine monomer components are continuously added to make the diamine monomer and the dianhydride monomer substantially equal in molar polymerization. In addition, the preparation method of the polyamide composition according to the present invention may include the following steps: mixing the diamine monomer with a solvent to prepare a mixture; mixing a conjugated conductive polymer in the above mixture; and mixing the dianhydride monomer in the above mixture. By mixing the diamine monomer, the conjugated conductive polymer and the dianhydride monomer in the above order, the dispersibility of the conjugated conductive polymer is improved, thereby improving the conductivity and transparency of the prepared polyamide composition and the polyimide obtained by curing it. At this time, based on the total weight of the composition, the content of the conjugated conductive polymer may be 0.01 wt % to 1 wt %. Specifically, the content of the conjugated conductive polymer may be 0.05 wt % to 1 wt %, 0.05 wt % to 0.9 wt %, 0.1 wt % to 1 wt %, 0.1 wt % to 0.7 wt %, 0.2 wt % to 1 wt %, 0.2 wt % to 0.9 wt %, 0.2 wt % to 0.7 wt %, 0.3 wt % to 1 wt %, 0.3 wt % to 0.9 wt %, 0.3 wt % to 0.7 wt %, 0.4 wt % to 0.7 wt %, or 0.4 wt % to 0.6 wt %. When the polyamide composition according to the present invention contains the conjugated conductive polymer in the above content, it has excellent transparency and excellent conductivity. The coefficient of thermal expansion (CTE) of the polyamide composition according to the present invention after curing may be 10 ppm/°C or less. For example, the upper limit of the CTE may be 9 ppm/°C, 8 ppm/°C, 7 ppm/°C, 6 ppm/°C, 5 ppm/°C or 4 ppm/°C or less, and the lower limit may be 0.1 ppm/°C, 1 ppm/°C, 2.0 ppm/°C or 3 ppm/°C or more. In one example, the coefficient of thermal expansion may be measured at 100°C to 450°C. For the CTE, a thermomechanical analyzer Q400 from TA can be used. After the polyimide is made into a film, it is cut into a size of 2 mm width and 10 mm length, and a tension of 0.05 N is applied in a nitrogen atmosphere. The temperature is raised from room temperature to 500° C. at a rate of 10° C./min, and then cooled again at a rate of 10° C./min., and the slope in the range of 100° C. to 450° C. can be measured. In one example, the glass transition temperature of the polyamide composition according to the present invention after curing can be 400° C. or more. For example, the lower limit of the glass transition temperature can be 403° C. or more, 405° C. or more, 410° C. or more, 420° C. or more, 430° C. or more, 440° C. or more, or 450° C. or more. The upper limit can be 600° C. or less. For the polyimide prepared by curing the polyamic acid composition, the above-mentioned glass transition temperature can be measured using TMA at 10°C/minute. The 1 wt% thermal decomposition temperature of the polyamic acid composition according to the present invention after curing can be above 500°C. The above-mentioned thermal decomposition temperature can be measured using TA's thermogravimetric analysis (thermogravimetric analysis) Q50 model. In one embodiment, the polyimide obtained by curing the above-mentioned polyamic acid is heated to 150°C at a rate of 10°C/minute in a nitrogen atmosphere, and then kept isothermal for 30 minutes to remove moisture. Thereafter, the temperature can be raised to 600°C at a rate of 10°C/minute to determine the temperature at which 1% weight loss occurs. For example, the lower limit of the thermal decomposition temperature may be 505°C or more, 510°C or more, 520°C or more, 530°C or more, 540°C or more, 550°C or more, 560°C or more, or 570°C or more. For example, the upper limit may be 800°C, 750°C, 700°C, 650°C, or less than 630°C. The dielectric constant of the polyamine composition according to the present invention at 120 Hz after curing may be 3.8 F/m or more. For example, the dielectric constant of the polyamine composition at 120 Hz after curing may be 3.9 F/m or more, 4.0 F/m or more, 4.1 F/m or more, 4.2 F/m or more, or 4.3 F/m or more, and the upper limit may be 5.0 or less. In the present invention, by having the dielectric constant of the above range, when using the polyamide composition or the polyamide prepared therefrom in electronic devices or the electronic industry, sufficient antistatic effect can be given. In addition, the elongation (Elongation) of the above-mentioned polyamide composition after curing can be more than 10%, for example, can be more than 11%, more than 12%, more than 15%, more than 20% or more than 25%. The upper limit is not particularly limited, but can be less than 40%. As for the above-mentioned elongation, the polyamide composition can be cured into a polyimide film and cut into a size of 10mm width and 40mm length, and the elongation can be measured by the Instron5564 UTM equipment of Instron company by ASTM D-882 method. In addition, the elastic modulus of the polyamine composition of the present invention after curing can be 5.0GPa or more. The lower limit of the above-mentioned elastic modulus can be, for example, 6.0GPa or more, 7.0GPa or more, 8.0GPa or more, or 9.0GPa or more. The upper limit is not particularly limited and can be 15GPa or less. In addition, the tensile strength of the polyamine composition after curing can be 180MPa or more. For example, the lower limit of the above-mentioned tensile strength can be 190MPa or more, 200MPa or more, 300MPa or more, 400MPa or more, 410MPa or more, 420MPa or more, or 440MPa or more, and the upper limit can be, for example, 550MPa or less, or 530MPa or less. As for the above-mentioned elastic modulus and tensile strength, the above-mentioned polyamide composition can be cured into a polyimide film and cut into a size of 10 mm width and 40 mm length, and the elastic modulus and tensile strength can be measured by using the Instron5564 UTM equipment of Instron Company by ASTM D-882 method. At this time, it can be measured under the condition of a cross head speed (Cross Head Speed) of 50 mm/minute. The above-mentioned polyamide composition can be a composition with low viscosity characteristics. The viscosity of the polyamide composition of the present invention measured under the conditions of a temperature of 23°C and a shear rate of 1s ^-1 can be 10,000 cP or less, 5,000 cP or less, 4,000 cP or less, 3,500 cP or less, 3,300 cP or less, 3,200 cP or less or 3,100 cP or less. The lower limit is not particularly limited, but may be 500 cP or more or 1,000 cP or more. For example, the above viscosity can be measured using Rheostress 600 model of Haake Company, and can be measured under the conditions of a shear rate of 1/s, a temperature of 23°C and a plate gap of 1 mm. The present invention can provide a precursor composition with excellent processability by adjusting the above viscosity range. In addition, the present invention provides a method for preparing polyimide, which includes forming a thin film of a polyamic acid composition prepared according to the above method for preparing a polyamic acid composition on a support and drying it to prepare a gel, and solidifying the above gel. Specifically, the method for preparing polyimide of the present invention may include the steps of forming a film of the polyamic acid composition on a support, drying the film to prepare a film-like gel, and curing the gel. The step of curing the gel may be performed by drying the polyamic acid composition formed on the support at a temperature of 20°C to 120°C for 5 minutes to 60 minutes to prepare a gel film, raising the temperature of the gel film to 30°C to 500°C at a rate of 1°C/min to 8°C/min, heat-treating at 450°C to 500°C for 5 minutes to 60 minutes, and cooling to 20°C to 120°C at a rate of 1°C/min to 8°C/min. The step of curing the gel film may be performed at 30° C. to 500° C. For example, the step of curing the gel film may be performed at 30° C. to 400° C., 30° C. to 300° C., 30° C. to 200° C., 30° C. to 100° C., 100° C. to 500° C., 100° C. to 300° C., 200° C. to 500° C., or 400° C. to 500° C. The thickness of the polyimide film may be 5 μm to 20 μm. For example, the thickness of the polyimide film may be 5 μm to 18 μm, 6 μm to 16 μm, 7 μm to 14 μm, 8 μm to 12 μm, or 9 μm to 11 μm. For example, the support may be an inorganic substrate. Examples of the inorganic substrate may include a glass substrate and a metal substrate, but a glass substrate is preferably used. As the glass substrate, sodium calcium glass, borosilicate glass, alkali-free glass, etc. may be used, but are not limited thereto. Since the polyimide according to the present invention has excellent heat resistance, transparency, and conductivity, it can be widely used as a high-tech core mechanical component requiring high heat resistance in electronic and electrical equipment that requires the above characteristics and is sensitive to electrostatic problems, flat panel display industry, semiconductor, solar cell industry, etc. Specifically, it can be usefully used for high-K transistors, polyimide substrates for oxide-TFTs, and polyimide substrates for LTPS-TFTs. Compared with the effects of the prior art, the polyamic acid composition according to the present invention and the polyimide prepared therefrom have high transparency and excellent conductivity. In particular, the polyamic acid composition according to the present invention and the polyimide prepared therefrom have high transparency and conductivity as described above, while also maintaining the excellent thermal and mechanical properties unique to polyimide.

The present invention is described in more detail below through the examples of the present invention and the comparative examples not of the present invention, but the scope of the present invention is not limited to the following examples. < Preparation of polyamine composition > Example 1 In a 500 ml reactor equipped with a stirrer and a nitrogen injection and discharge pipe, nitrogen is injected while adding N,N-dimethylacrylamide (DMPA) as a solvent. After setting the temperature of the reactor to 50°C, p-phenylenediamine (PPD) is added as a diamine monomer, and then, 0.1 wt% of polypyrrole with a membrane conductivity (Dried Cast Film Conductivity) of 0.006 S/cm is added as a conductive polymer relative to the total weight of the composition to completely dissolve it. Then, 100 mol% of biphenyltetracarboxylic dianhydride (BPDA) was added as a dianhydride monomer, and stirring was continued for 120 minutes to prepare a polymerized polyamine composition. Examples 2 to 9 prepared polyamine compositions in the same manner as Example 1, except that the monomer components and content ratios, and the solvent components and content ratios were adjusted as shown in Table 1 below. Comparative Examples 1 to 7 prepared polyamine solutions in the same manner as Example 1, except that the components and content of the conductive polymer were adjusted as shown in Table 1 below. < Preparation of polyimide for measuring physical properties > Bubbles were removed from the polyimide solutions prepared in the above-mentioned examples and comparative examples by high-speed rotation at 1,500 rpm or more. Thereafter, the defoamed polyimide solution was applied to a glass substrate using a spin coater. Thereafter, a gel film was prepared by drying at 120°C for 30 minutes in a nitrogen atmosphere, the temperature of the gel film was increased to 450°C at a rate of 2°C/min, and after heat treatment at 450°C for 60 minutes, it was cooled to 30°C at a rate of 2°C/min to obtain a 10μm polyimide film. Thereafter, the polyimide film was peeled off from the glass substrate by dipping in distilled water. The physical properties of the prepared polyimide films were measured using the following methods, and the results are shown in Tables 2 and 3 below. Experimental Example 1 - Viscosity For the polyamide solutions prepared in the Examples and Comparative Examples, the viscosity was measured using a Rheostress 600 model from Haake at a shear rate of 1/s, a temperature of 23°C, and a plate gap of 1 mm. Experimental Example 2 - Thickness Measurement The thickness of the prepared polyimide film was measured using an Electric Film Thickness Tester from Anritsu. Experimental Example 3 - Light Transmittance For the 10 μm polyimide film prepared by curing the polyamide solution of the embodiment and the comparative example, the transmittance at 470 nm was measured in the transmission mode using Lambda 465 of the UV-Vis Spectrophotometer of Perkin Elmer. Experimental Example 4 : Dielectric Constant Determination The dielectric constant of the polyimide film prepared in the above-mentioned embodiment and the comparative example was measured at 120 Hz using the SPDR measuring device of Keysight. Experimental Example 5 - Surface Resistivity The surface resistance was measured using KEYSIGHT/B2987A according to ASTM D257. Specifically, a 110mm×110mm polyimide film sample was measured at a temperature of 23±3°C, a power supply voltage of 300V, a load scale of 5kgf, and a charging time of 60 seconds. Experimental Example 6-CTE Using TA's thermomechanical analyzer Q400, after polyimide was made into a film, it was cut into a size of 2 mm width and 10 mm length, and a tension of 0.05N was applied in a nitrogen atmosphere, and the temperature was raised from room temperature to 500°C at a rate of 10°C/min, and then cooled again at a rate of 10°C/min, and the slope in the range from 100°C to the glass transition temperature was measured. Experimental Example 7- Glass transition temperature For the polyimide film prepared by curing the polyamide acid solution of the example and the comparative example, the point where TMA rapidly expanded under the condition of 10°C/min was used as the starting point (On-set point) for measurement. Experimental Example 8- Thermal Decomposition Temperature (Td) of Weight Percentage Using a thermogravimetric analysis (thermogravimetric analysis) Q50 model of TA Company, the temperature of the polyimide film was raised to 150°C at a rate of 10°C/min in a nitrogen atmosphere, and then kept isothermally for 30 minutes to remove moisture. Thereafter, the temperature was raised to 600°C at a rate of 10°C/min to determine the temperature at which 1% weight loss occurred. Experimental Example 9- Elongation Determination After the polyimide film prepared by curing the polyamide solution of the embodiment and the comparative example was cut into a size of 10 mm width and 40 mm length, the elongation was measured using the Instron 5564 UTM equipment of Instron Company by the ASTM D-882 method. Experimental Example 10 - Determination of elastic modulus and tensile strength The polyimide film prepared by curing the polyamide solution of the embodiment and the comparative example and cutting it into a size of 10 mm width and 40 mm length can be measured for elastic modulus and tensile strength using the Instron 5564 UTM equipment of Instron Company by the ASTM D-882 method. At this time, the measurement can be carried out under the condition of a crosshead speed of 50 mm/min.

Claims (10)

A polyamine composition comprises: a polymer having polymerized units derived from dianhydride monomers and diamine monomers; and a conjugated conductive polymer, which is polypyrrole, and has a surface resistance of 1.0×10 ¹³ Ω/□ or less measured according to ASTM D257 after curing. As in claim 1, the polyamine composition, wherein the content of the above-mentioned conjugated conductive polymer is 0.01 wt% to 1 wt% based on the total weight of the polyamine composition. The polyamide composition of claim 1, wherein the diamine monomer includes at least one selected from the group consisting of 1,4-diaminobenzene, 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether, 4,4'-methylenediamine, 4,4-diaminophenylaniline, N,N-bis(4-aminophenyl)benzene-1,4-diformamide, 2,2-dimethylbenzidine, 2,2-bis(trifluoromethyl)benzidine, 1,4-bisaminophenoxybenzene, bisaminophenoxybenzene, 2,2-bisaminophenoxyphenylpropane and 2,2-bisaminophenoxyphenylhexafluoropropane. As in claim 1, the polyamine composition, wherein the dianhydride monomer includes at least one selected from the group consisting of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, oxyphthalic dianhydride, 4,4-(hexafluoroisopropylidene)phthalic anhydride and terephthalic bis(trimellitic anhydride). The polyamine composition of claim 1, further comprising at least one solvent selected from the group consisting of N,N-diethylacetamide, N,N-dimethylpropionamide, 3-methoxy-N,N-dimethylpropionamide, N-methyl-2-pyrrolidone, γ-butyrolactone and diethylene glycol dimethyl ether. The polyamine composition of claim 1, wherein the solid content is 5% to 30% by weight. The polyamide composition of claim 1, wherein the thermal expansion coefficient after curing is less than 10ppm/℃. The polyamide composition of claim 1, wherein the dielectric constant at 120 Hz after curing is greater than 3.8 F/m. A method for preparing a polyamide composition as claimed in claim 1, comprising the following steps: mixing a diamine monomer with a solvent to prepare a mixture; mixing a conjugated conductive polymer into the mixture; and mixing a dianhydride monomer into the mixture. A polyimide, which includes a cured product of the polyamide composition as claimed in claim 1.