Polyamic acid composition and polyimide containing the same

Abstract

The present application relates to a polyamic acid composition and a polyimide containing the same, and provides a polyamic acid composition having a high concentration of polyamic acid solids, low viscosity, and excellent heat resistance, dimensional stability, and mechanical properties after curing, as well as excellent electrical properties, and a polyimide and polyimide film produced therefrom.

Description

[Technical Field]

[0001] Cross-Citation of Related Applications This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0155544, filed on November 19, 2020, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] Technical Field The present application relates to polyamic acid compositions and polyimides containing the same. [Background technology]

[0003] Polyimide (PI) is a thermally stable polymeric 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.

[0004] Furthermore, polyimides have excellent electrical properties, such as insulating properties and a low dielectric constant, and are attracting attention as highly functional polymeric materials applicable to a wide range of industrial fields, including electronics, communications, and optics. The insulating layer (insulating coating) that covers a conductor must have excellent insulating properties, adhesion to the conductor, heat resistance, and mechanical strength. Furthermore, in electrical equipment requiring high voltages, such as high-voltage motors, high voltages are applied to the insulated wires that make up the electrical equipment, which can easily cause partial discharges (corona discharges) on the surface of the insulating coating. Corona discharges can cause localized temperature increases and the generation of ozone or ions, which can result in deterioration of the insulating coating of the insulated wire, leading to premature dielectric breakdown and shortening the lifespan of the electrical equipment.

[0005] Recently, as various electronic devices have become thinner, lighter, and smaller, much research has been conducted into using thin, lightweight, and flexible polyimide films as insulating materials for circuit boards or display substrates that can replace glass substrates for displays.

[0006] In particular, in the case of polyimide films used for circuit boards or display substrates which are manufactured at high process temperatures, it is necessary to ensure higher levels of dimensional stability, heat resistance and mechanical properties.

[0007] One method for ensuring such properties is to increase the molecular weight of the polyimide.

[0008] The more imide groups there are in a molecule, the more the heat resistance and mechanical properties of the polyimide film can be improved. The longer the polymer chain, the higher the proportion of imide groups. Therefore, producing a polyimide with a high molecular weight is advantageous for ensuring the required physical properties.

[0009] In order to produce a polyimide having a high molecular weight, it is common to produce a polyamic acid, which is a precursor thereof, with a high molecular weight and then imidize it through a heat treatment.

[0010] However, as the molecular weight of the polyamic acid increases, the viscosity of the polyamic acid solution in which the polyamic acid is dissolved in a solvent increases, resulting in a decrease in flowability and a very poor processability.

[0011] In addition, in order to reduce the viscosity of the polyamic acid while maintaining the molecular weight of the polyamic acid, it is possible to consider a method of decreasing the solid content and increasing the solvent content. However, in this case, a large amount of solvent must be removed during the curing process, which increases the manufacturing cost and process time.

[0012] Therefore, there is a strong need for research into polyimide films that can satisfy processability by maintaining low viscosity even when the solid content of the polyamic acid solution is high, and that can simultaneously satisfy heat resistance, mechanical properties, and electrical properties of the polyimide produced from the polyamic acid solution. Summary of the Invention [Problem to be solved by the invention]

[0013] The present application provides a polyamic acid composition having a high concentration of polyamic acid solids and low viscosity, and having excellent heat resistance, dimensional stability, and mechanical properties as well as excellent electrical properties after curing, as well as a polyimide and polyimide film produced therefrom. [Means for solving the problem]

[0014] The present application relates to a polyamic acid composition. The polyamic acid composition according to the present application may include a polyamic acid containing polymerized units of a dianhydride monomer component and a diamine monomer component, and a solvent. The solvent may also include a first solvent and a second solvent that is different from the first solvent. The solvent may be an organic solvent. The polyamic acid composition according to the present application has a corona half-life of 40 seconds or more after curing according to JIS L 1094 standard, and a volume resistivity of 1.75×10 measured at 23°C and 50% relative humidity according to ASTM D257 standard after curing. 16 The lower limit of the corona half-life may be, for example, 45, 48, 50, 52, 55, 58, 60, 62, 63, 66, 68, 70, 75, 78, or 80 seconds or more, and the upper limit may be, for example, 100, 90, 88, 85, 80, 75, 70, 65, 60, or 55 seconds or less. In addition, the lower limit of the volume resistivity may be 1.75×10 16 , 1.78×10 16 , 1.8×10 16 , 1.83×10 16 , 1.85×10 16 , 1.88×10 16 , 1.9×10 16 , 1.92 × 10 16 , 2.0×10 16 , 2.28×10 16 , 2.4 × 10 16 , 2.5×10 16 , 2.75×10 16 , 2.8×10 16 , 3.0×10 16 , 3.3 × 10 16 , 3.5×10 16 , 3.8×1016 , 4.0×10 16 , 4.2 × 10 16 , 4.5×10 16 , 5.0×10 16 , 5.3 × 10 16 , 5.5×10 16 or 5.6 x 10 16 The upper limit may be, for example, 9.9 × 10 16 , 9.0×10 16 , 8.0×10 16 , 7.0×10 16 , 6.0×10 16 , 5.8×10 16 , 5.6×10 16 , 5.3 × 10 16 , 5.0×10 16 , 4.5×10 16 , 4.0×10 16 , 3.5×10 16 , 3.0×10 16 , 2.5×10 16 , 2.3 × 10 16 , 2.0×10 16 or 1.9 x 10 16 The corona half-life may be Ω·cm or less. The corona half-life was measured by applying a DC voltage to a sample in the form of corona discharge, and when the detected value reached a saturated value, the high voltage application was stopped, and the time (half-life) required for the potential on the sample surface to decay by half was measured. By adjusting the composition and physical properties, the present application provides a polyamic acid composition that ensures processability with low viscosity and has excellent heat resistance, dimensional stability, and mechanical properties as well as excellent electrical properties after curing.

[0015] In the present application, when temperature affects the measurement of physical properties, the measurements may be made at room temperature of 23°C unless otherwise specified.

[0016] The present application may include a first solvent and a second solvent. As mentioned above, the second solvent may be a different component than the first solvent.

[0017] In one example, the first solvent may have a boiling point of 150°C or higher, and the second solvent may have a boiling point lower than that of the first solvent. That is, the first solvent may have a boiling point higher than that of the second solvent. The second solvent may have a boiling point in the range of 30°C or higher and lower than 150°C. The lower limit of the boiling point of the first solvent may 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 may 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. The lower limit of the boiling point of the second solvent may be, for example, 35°C, 40°C, 45°C, 50°C, 53°C, 58°C, 60°C, or 63°C or higher, and the upper limit may be, for example, 148°C, 145°C, 130°C, 120°C, 110°C, 105°C, 95°C, 93°C, 88°C, 85°C, 80°C, 75°C, 73°C, 70°C, or 68°C or lower. In the present application, polyimide with desired physical properties can be produced by using two solvents with different boiling points.

[0018] In one example, the second solvent may have a solubility of the dianhydride monomer of less than 1.5 g / 100 g. That is, the second solvent may have a solubility of the dianhydride monomer of less than 1.5 g / 100 g. The upper limit of the solubility range may be, for example, 1.3 g / 100 g, 1.2 g / 100 g, 1.1 g / 100 g, 1.0 g / 100 g, 0.9 g / 100 g, 0.8 g / 100 g, 0.7 g / 100 g, 0.6 g / 100 g, 0.5 g / 100 g, 0.4 g / 100 g, 0.3 g / 100 g, or 0.25 g / 100 g. The average molecular weight may be, for example, 0.23 g / 100 g, 0.21 g / 100 g, 0.2 g / 100 g, or 0.15 g / 100 g or less, and the lower limit may be, for example, 0 g / 100 g, 0.01 g / 100 g, 0.05 g / 100 g, 0.08 g / 100 g, 0.09 g / 100 g, or 0.15 g / 100 g or more. The present application provides a polyamic acid composition with desired physical properties by including a second solvent that has low solubility for the dianhydride monomer contained in the polymerized units or the dianhydride monomer that is not polymerized. In the present application, when a physical property measured is temperature-sensitive, the property may be measured at room temperature (23°C) unless otherwise specified.

[0019] In a specific example of the present application, the first solvent may have a solubility for the dianhydride monomer of, for example, 1.5 g / 100 g or more. The lower limit of the solubility may be, for example, 1.6 g / 100 g, 1.65 g / 100 g, 1.7 g / 100 g, 2 g / 100 g, 2.5 g / 100 g, 5 g / 100 g, 10 g / 100 g, 30 g / 100 g, 45 g / 100 g, 50 g / 100 g, or 51 g / 100 g or more, and the upper limit may be, for example, 80 g / 100 g, 70 g / 100 g, 60 g / 100 g, 55 g / 100 g, 53 g / 100 g, 48 g / 100 g, 25 g / 100 g, 10 g / 100 g, 5 g / 100 g, or 3 g / 100 g or less. The solubility of the first solvent may be higher than that of the second solvent.

[0020] The first solvent according to the present application is not particularly limited as long as it is a solvent capable of dissolving polyamic acid. The first solvent may also be a polar solvent. For example, the first solvent may be an amide solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone. For example, the first solvent may have an amide group or a ketone group in its molecular structure. The first solvent may have a lower polarity than the second solvent.

[0021] The first solvent may be, for example, an aprotic polar solvent. The second solvent may be an aprotic polar solvent or a protic polar solvent. The second solvent may have at least one polar functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an alkoxy group, an ester group, and an ether group. For example, the second solvent may include an alcohol solvent such as methanol, ethanol, 1-propanol, butyl alcohol, isobutyl alcohol, or 2-propanol; an ester solvent such as methyl acetate, ethyl acetate, or isopropyl acetate; a carboxylic acid solvent such as formic acid, acetic acid, propionic acid, butyric acid, or lactic acid; an ether solvent such as dimethyl ether, diethyl ether, diisopropyl ether, or dimethoxyethane methyl t-butyl ether; dimethyl carbonate; methyl methacrylate; or propylene glycol monomethyl ether acetate.

[0022] As described above, the present application may include both the first solvent and the second solvent. In this case, the first solvent may be contained in a greater amount than the second solvent. The second solvent may be contained in a ratio of 0.01 to 10 parts by weight per 100 parts by weight of the first solvent. The lower limit of the content may be, for example, 0.02 parts by weight, 0.03 parts by weight, 0.04 parts by weight, 0.1 parts by weight, 0.3 parts by weight, 0.5 parts by weight, 0.8 parts by weight, 1 part by weight, or 2 parts by weight or more, and the upper limit may be, for example, 8 parts by weight, 6 parts by weight, 5 parts by weight, 4.5 parts by weight, 4 parts by weight, 3 parts by weight, 2.5 parts by weight, 1.5 parts by weight, 1.2 parts by weight, 0.95 parts by weight, 0.4 parts by weight, 0.15 parts by weight, or 0.09 parts by weight or less.

[0023] In one example, as described above, the polyamic acid composition of the present application may include a second solvent, and the second solvent may be present in a range of 0.01 to 10 wt% of the total polyamic acid composition. The lower limit of the content of the second solvent may be, for example, 0.015 wt%, 0.03 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, or 2 wt% or more, and the upper limit may be, for example, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5.5 wt%, 5.3 wt%, 5 wt%, 4.8 wt%, 4.5 wt%, 4 wt%, 3 wt%, 2.5 wt%, 1.5 wt%, 1.2 wt%, 0.95 wt%, or 0.4 wt% or less. The first solvent may be present in a range of 60 to 95 wt% of the total polyamic acid composition. The lower limit of the content of the first solvent may be, for example, 65 wt%, 68 wt%, 70 wt%, 73 wt%, 75 wt%, 78 wt%, or 80 wt%, and the upper limit may be, for example, 93 wt%, 90 wt%, 88 wt%, 85 wt%, 83 wt%, 81 wt%, or 79 wt%. The polyamic acid composition according to the present application includes a dianhydride monomer component and a diamine monomer component, and the two monomers form polymerization units together. However, a portion of the dianhydride monomer undergoes ring-opening by the organic solvent and therefore does not participate in the polymerization reaction. The dianhydride monomer that is ring-opened without polymerization acts as a diluent monomer and can adjust the viscosity of the overall polyamic acid composition to a relatively low level. The dianhydride monomer having a ring-opened structure participates in the imidization reaction to realize the desired polyimide.

[0024] In one embodiment, the dianhydride monomer may include a monomer having a ring-opened structure that does not polymerize with monomers contained in the polymerization units. That is, some or all of the dianhydride monomers may be contained in the polymerization units, and the dianhydride monomers not contained in the polymerization units may have a ring-opened structure due to the solvent of the present application. In the polyamic acid composition of the present application, the dianhydride monomer may exist in the form of an aromatic carboxylic acid having two or more carboxylic acids without being polymerized. The aromatic carboxylic acid may exist as a monomer before curing, thereby reducing the viscosity of the overall polyamic acid composition and improving processability. The aromatic carboxylic acid having two or more carboxylic acids may polymerize with the dianhydride monomer to the main chain after curing, thereby increasing the overall polymer chain length. This polymer may exhibit excellent heat resistance, dimensional stability, and mechanical and electrical properties.

[0025] Specifically, during heat treatment of the polyamic acid composition to imidize the polyimide, the aromatic carboxylic acid having two or more carboxylic acids undergoes a ring-closing dehydration reaction to form a dianhydride monomer, which reacts with the terminal amine group of the polyamic acid chain or the polyimide chain to increase the length of the polymer chain. As a result, the dimensional stability and thermal stability at high temperatures of the produced polyimide film can be improved, and the mechanical properties at room temperature can be enhanced.

[0026] As described above, the polyamic acid composition of the present application may include polymerized units of a diamine monomer and a dianhydride monomer. In this specification, the term "polyimide precursor composition" may be used interchangeably with the term "polyamic acid composition" or "polyamic acid solution."

[0027] The dianhydride monomer that can be used to prepare the polyamic acid solution may be an aromatic tetracarboxylic acid dianhydride, and the aromatic tetracarboxylic acid dianhydride may be pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (or a-BPDA), oxydiphthalic acid dianhydride (or ODPA), diphenylsulfonyl ether dianhydride (or α-BPDA), hydroxy ... Sulfon-3,4,3′,4′-tetracarboxylic acid 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 acid dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride Anhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis(trimellitic acid monoester acid anhydride), p-biphenylene bis(trimellitic acid monoester acid anhydride), m-terphenyl-3,4,3′,4′-tetracarboxylic acid dianhydride, p-terphenyl-3,4,3′,4′-tetracarboxylic acid dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4 Examples of such dianhydrides include 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 acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride.

[0028] The dianhydride monomers may be used alone or in combination of two or more, as needed, and may include, for example, 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), oxydiphthalic dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA), p-phenylenebis(trimellitate anhydride) (TAHQ), or 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA).

[0029] In a specific example of the present application, the dianhydride monomer may include a dianhydride monomer having one benzene ring and a dianhydride monomer having two or more benzene rings. The dianhydride monomer having one benzene ring and the dianhydride monomer having two or more benzene rings may be included in a molar ratio of 20 to 60 mol% and 40 to 90 mol%, 25 to 55 mol% and 45 to 80 mol%, or 35 to 53 mol% and 48 to 75 mol%, respectively. By including the dianhydride monomer, the present application can achieve both excellent adhesive strength and desired levels of mechanical properties.

[0030] The diamine monomers that can be used to produce the polyamic acid solution are aromatic diamines, and can be categorized as follows: 1) Diamines with a relatively rigid structure, such as 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid (or DABA); 2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenyl Phenylmethane, 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 Diamines having two benzene nuclei in their structure, such as ethane, 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, etc.; 3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q), 1,4-bis(4-aminophenoxy)benzene (or TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3′-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3′-diamino-4,4′-di(4-phenylphenoxy)benzophenone diamines having three benzene nuclei in their structure, such as 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, and the like; 4) 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl] bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-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 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 Diamines having four benzene nuclei in their structure, such as 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane (BAPP), 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0031] In one example, the diamine monomer according to the present application may include 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-dicarboxamide (BPTPA), 2,2-dimethylbenzidine (M-TOLIDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP), 2,2′-bis(trifluoromethyl)benzidine (TFMB), or 9,9-bis(4-aminophenyl)fluorene (BAPF).

[0032] In one specific example, the polyamic acid composition may contain 9 to 35 wt %, 10 to 33 wt %, 10 to 30 wt %, 15 to 25 wt %, or 18 to 23 wt % of solids based on the total weight. By adjusting the solids content of the polyamic acid composition to be relatively high, the present application can control an increase in viscosity while maintaining desired physical properties after curing, and prevent increases in manufacturing costs and process time that would be required to remove a large amount of solvent during the curing process.

[0033] The polyamic acid composition of the present application may be a composition having low viscosity characteristics. The polyamic acid composition of the present application may be a composition having low viscosity characteristics at a temperature of 23° C. and 1 s -1The viscosity measured under conditions of a shear rate of 1 / s may be 50,000 cP or less, 40,000 cP or less, 30,000 cP or less, 20,000 cP or less, 10,000 cP or less, or 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. The viscosity may be measured, for example, using a Haake Rheostress 600 under conditions of a shear rate of 1 / s, a temperature of 23°C, and a plate gap of 1 mm. By adjusting the viscosity range, the present application provides a precursor composition with excellent processability, which enables the formation of a film or substrate with desired physical properties during film or substrate formation.

[0034] In one embodiment, the polyamic acid composition of the present application may have a weight average molecular weight after curing of 10,000 to 500,000 g / mol, 15,000 to 400,000 g / mol, 18,000 to 300,000 g / mol, 20,000 to 200,000 g / mol, 25,000 to 100,000 g / mol, or 30,000 to 80,000 g / mol. In the present application, the term weight average molecular weight refers to a value measured by GPC (Gel Permeation Chromatography) relative to standard polystyrene.

[0035] The polyamic acid composition according to the present application may further contain inorganic particles. The inorganic particles may have an average particle size, for example, within a range of 5 to 80 nm. In specific examples, the lower limit may be 8 nm, 10 nm, 15 nm, 18 nm, 20 nm, or 25 nm, and the upper limit may be, for example, 70 nm, 60 nm, 55 nm, 48 nm, or 40 nm. In this specification, the average particle size may be measured by D50 particle size analysis. By adjusting the particle size range, the present application can improve compatibility with the polyamic acid and achieve desired physical properties after curing.

[0036] The type of inorganic particles is not particularly limited, and may include silica, alumina, titanium dioxide, zirconia, yttria, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandium oxide, or barium oxide. Furthermore, the inorganic particles of the present application may include a surface treatment agent on their surfaces. The surface treatment agent may include, for example, a silane coupling agent. The silane coupling agent may be one or more selected from the group consisting of epoxy-based, amino-based, and thiol-based compounds. Specifically, the epoxy-based compound may include glycidoxypropyl trimethoxysilane (GPTMS), the amino-based compound may include aminopropyl trimethoxysilane ((3-Aminopropyl)trimethoxysilane (APTMS), and the thiol-based compound may include mercaptopropyl trimethoxysilane (MPTMS), but are not limited thereto. The surface treatment agent may include dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), or tetraethoxysilane (TEOS). In the present application, the surfaces of inorganic particles may be treated with one type of surface treatment agent or two different types of surface treatment agents. The inorganic particles may be contained in an amount ranging from 1 to 20 parts by weight per 100 parts by weight of polyamic acid. The lower limit of the content may be, for example, 3 parts by weight, 5 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight or more, and the upper limit may be, for example, 18 parts by weight, 15 parts by weight, 13 parts by weight, or 8 parts by weight or less. By incorporating the inorganic particles into a polyamic acid composition, the present application can improve dispersibility and miscibility, thereby achieving adhesiveness and heat resistance durability after curing.

[0037] The polyamic acid composition may have a coefficient of thermal expansion (CTE) after curing in the range of 40 ppm / ° C. or less. In one specific example, the upper limit of the CTE may be 40 ppm / °C, 35 ppm / °C, 30 ppm / °C, 25 ppm / °C, 20 ppm / °C, 18 ppm / °C, 15 ppm / °C, 13 ppm / °C, 10 ppm / °C, 8 ppm / °C, 7 ppm / °C, 6 ppm / °C, 5 ppm / °C, 4.8 ppm / °C, 4.3 ppm / °C, 4 ppm / °C, 3.7 ppm / °C, 3.5 ppm / °C, 3 ppm / °C, 2.8 ppm / °C, or 2.6 ppm / °C or less, and the lower limit may be, for example, 0.1 ppm / °C, 1 ppm / °C, 2.0 ppm / °C, 2.6 ppm / °C, 2.8 ppm / °C, 3.5 ppm / °C, or 4 ppm / °C or more. In one example, the thermal expansion coefficient may be measured at 100 to 450°C. The CTE can be measured using a TA thermomechanical analyzer, model Q400. After preparing a polyimide film and cutting it into a 2 mm wide and 10 mm long piece, the film is heated from room temperature to 500°C at a rate of 10°C / min under a nitrogen atmosphere with a tension of 0.05 N, and then cooled at a rate of 10°C / min to measure the slope from 100°C to 450°C.

[0038] The polyamic acid composition may have an elongation of 10% or more after curing, and in specific examples, may be 12% or more, 13% or more, 15% or more, 18% or more, 20-60%, 20-50%, 20-40%, 20-38%, 22-36%, 24-33%, or 25-29%. The elongation can be measured according to ASTM D-882 method using an Instron 5564 UTM instrument manufactured by Instron Corporation after curing the polyamic acid composition into a polyimide film and cutting it into a 10 mm wide x 40 mm long piece.

[0039] The polyamic acid composition of the present application may have a modulus of elasticity after curing in the range of 6.0 GPa to 11 GPa. The lower limit of the modulus of elasticity may be, for example, 6.5 GPa, 7.0 GPa, 7.5 GPa, 8.0 GPa, 8.5 GPa, 9.0 GPa, 9.3 GPa, 9.55 GPa, 9.65 GPa, 9.8 GPa, 9.9 GPa, 9.95 GPa, 10.0 GPa, or 10.3 GPa or more, and the upper limit may be, for example, 10.8 GPa, 10.5 GPa, 10.2 GPa, or 10.0 GPa or less. The polyamic acid composition may have a tensile strength after curing in the range of 300 MPa to 600 MPa. The lower limit of the tensile strength may be, for example, 350 MPa, 400 MPa, 450 MPa, 480 MPa, 500 MPa, 530 MPa, or 540 MPa, and the upper limit may be, for example, 580 MPa, 570 MPa, 560 MPa, 545 MPa, 530 MPa, or 500 MPa. The elastic modulus and tensile strength can be measured by curing the polyamic acid composition to prepare a polyimide film, cutting the film into a width of 10 mm and a length of 40 mm, and then measuring the elastic modulus and tensile strength according to ASTM D-882 using an Instron 5564 UTM instrument manufactured by Instron. The measurement can be performed at a crosshead speed of 50 mm / min.

[0040] In one example, the polyamic acid composition according to the present application may have a glass transition temperature after curing in the range of 350°C or higher. The upper limit of the glass transition temperature may be 800°C or 700°C or lower, and the lower limit may be 360°C, 365°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 425°C, 430°C, 440°C, 445°C, 448°C, 450°C, 453°C, 455°C, or 458°C or higher. The glass transition temperature can be measured using TMA at 10°C / min on a polyimide prepared by curing the polyamic acid composition.

[0041] The polyamic acid composition according to the present application may have a 1 wt % thermal decomposition temperature of 500°C or higher after curing. The thermal decomposition temperature can be measured using a thermogravimetric analyzer (Model Q50) manufactured by TA Corporation. In a specific example, the polyimide obtained by curing the polyamic acid is heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, and then maintained at the same temperature for 30 minutes to remove moisture. The temperature is then raised to 600°C at a rate of 10°C / min, and the temperature at which a 1% weight loss occurs can be measured. The lower limit of the thermal decomposition temperature may be, for example, 510°C, 515°C, 518°C, 523°C, 525°C, 528°C, 530°C, 535°C, 538°C, 545°C, 550°C, 560°C, 565°C, 568°C, 570°C, 580°C, 583°C, 585°C, 588°C, 590°C, or 593°C, and the upper limit may be, for example, 800°C, 750°C, 700°C, 650°C, or 630°C.

[0042] Furthermore, the polyamic acid composition according to the present application may have a light transmittance of 50 to 80% in any one wavelength band in the visible light region (380 to 780 nm) after curing. The lower limit of the light transmittance may be, for example, 55%, 58%, 60%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, or 71% or more, and the upper limit may be, for example, 78%, 75%, 73%, 72%, 71%, 69%, 68%, 67%, 66%, 65%, or 64% or less.

[0043] The present application also relates to a method for producing the aforementioned polyamic acid composition.

[0044] The preparation method may include a heating step at at least 50°C. The heating step may be, for example, 55°C or higher, 58°C or higher, 60°C or higher, 63°C or higher, 65°C or higher, or 68°C or higher, with an upper limit of, for example, 100°C or lower, 98°C or lower, 93°C or lower, 88°C or lower, 85°C or lower, 83°C or lower, 80°C or lower, 78°C or lower, 75°C or lower, 73°C or lower, or 71°C or lower. The present application may also include a step of mixing an organic solvent and a dianhydride monomer component prior to the heating step. The heating step may be performed after the mixing step, so heating may be performed with the organic solvent and dianhydride monomer still present. By performing a heating step at a higher temperature than conventional processes, the present application can obtain the desired polyamic acid structure and increase the overall polymer chain length after curing, resulting in a polymer that exhibits excellent heat resistance, dimensional stability, and mechanical properties.

[0045] In an embodiment, the method for producing the polyamic acid composition of the present application can include, for example, the following polymerization method. For example, (1) a method in which the entire amount of diamine monomer is placed in a solvent, and then a dianhydride monomer is added in an amount substantially equimolar to the diamine monomer to polymerize it; (2) A method in which the entire amount of the dianhydride monomer is placed in a solvent, and then a diamine monomer is added in an amount substantially equimolar to the dianhydride monomer to polymerize it; (3) A method in which a part of the diamine monomer components is placed in a solvent, and then a part of the dianhydride monomer components is mixed in a ratio of about 95 to 105 mol % relative to the reaction components, and the remaining diamine monomer components are added, and then the remaining dianhydride monomer components are added successively to this, so that the diamine monomer and the dianhydride monomer are polymerized in substantially equimolar amounts; (4) A method in which a dianhydride monomer is placed in a solvent, and then a portion of a diamine compound is mixed in a ratio of 95 to 105 mol % relative to the reaction components, and then other dianhydride monomer components are added, followed by the remaining diamine monomer components, so that the diamine monomer and the dianhydride monomer are substantially equimolar, thereby polymerizing the mixture; (5) A method of forming a first composition by reacting some diamine monomer components and some dianhydride monomer components in a solvent so that one of them is in excess, and then forming a second composition by reacting some diamine monomer components and some dianhydride monomer components in another solvent so that one of them is in excess, and then mixing the first and second compositions to complete the polymerization. In this case, if the diamine monomer component is in excess when forming the first composition, the dianhydride monomer component is in excess in the second composition, and if the dianhydride monomer component is in excess in the first composition, the diamine monomer component is in excess in the second composition, and then mixing the first and second compositions to polymerize so that the total diamine monomer components and dianhydride monomer components used in these reactions are substantially equimolar.

[0046] The polymerization method is not limited to the above examples, and any known method can be used.

[0047] The step of preparing the polyamic acid composition may be carried out at 30 to 80°C.

[0048] The present application also relates to a polyimide containing a cured product of the polyamic acid composition. The present application also provides a polyimide film containing the polyimide. The polyimide film may be a polyimide film for a substrate, and in a specific example, may be a polyimide film for a TFT substrate.

[0049] The present invention also provides a method for producing a polyimide film, comprising the steps of forming a film of the polyamic acid composition produced by the method for producing a polyamic acid composition on a support, drying the film to produce a gel film, and curing the gel film.

[0050] Specifically, in the method for producing a polyimide film of the present invention, the step of forming a film of the polyimide precursor composition on a support and drying the film to form a gel film may be performed by drying the polyimide precursor composition formed on the support at a temperature of 20 to 120°C for 5 to 60 minutes to form a gel film, heating the gel film to 30 to 500°C at a rate of 1 to 8°C / min, heat-treating the gel film at 450 to 500°C for 5 to 60 minutes, and cooling the gel film to 20 to 120°C at a rate of 1 to 8°C / min.

[0051] The step of curing the gel film may be performed at 30 to 500°C. For example, the step of curing the gel film may be performed at 30 to 400°C, 30 to 300°C, 30 to 200°C, 30 to 100°C, 100 to 500°C, 100 to 300°C, 200 to 500°C, or 400 to 500°C.

[0052] The polyimide film has a thickness of 10 to 20 μm. For example, the thickness of the polyimide film may be 10 to 18 μm, 10 to 16 μm, 10 to 14 μm, 12 to 20 μm, 14 to 20 μm, 16 to 20 μm, or 18 to 20 μm.

[0053] The support may be, for example, an inorganic substrate. Examples of inorganic substrates include glass substrates and metal substrates. However, it is preferable to use a glass substrate. The glass substrate may be, but is not limited to, soda-lime glass, borosilicate glass, alkali-free glass, or the like. [Effects of the Invention]

[0054] The present application provides a polyamic acid composition having a high concentration of polyamic acid solids and low viscosity, and having excellent heat resistance, dimensional stability, and mechanical properties as well as excellent electrical properties after curing, as well as a polyimide and polyimide film produced therefrom. DETAILED DESCRIPTION OF THE INVENTION

[0055] The present invention will be described in more detail below based on examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited to the examples presented below.

[0056] <Production of Polyamic Acid Solution> Example 1 N-methylpyrrolidone (NMP, 99 wt%) was added as the first solvent to a 500 ml reactor equipped with a stirrer and a nitrogen inlet / outlet tube while injecting nitrogen. Then, methanol (MeOH) was added as a second solvent at a ratio of 1 wt% and stirred. The reactor temperature was set to 70°C, and biphenyltetracarboxylic acid dianhydride (BPDA) was added as the dianhydride monomer and reacted. The temperature was then lowered to 30°C under a nitrogen atmosphere, and para-phenylenediamine (PPD) as the diamine monomer was completely dissolved in the reaction solution and rapidly stirred. The mixture was then heated to 40°C and stirred for 120 minutes to produce a polyamic acid solution.

[0057] Examples 2 to 6 A polyamic acid solution was prepared in the same manner as in Example 1, except that the monomer content and the type and content of the solvent were adjusted as shown in Table 1.

[0058] Comparative Examples 1 to 6 A polyamic acid solution was prepared in the same manner as in Example 1, except that the monomer and content ratio were adjusted as shown in Table 1 and the second solvent was omitted.

[0059] [Table 1]

[0060] <Preparation of polyimide for physical property measurement> The polyamic acid compositions prepared in the examples and comparative examples were spun at a high speed of 1,500 rpm or more to remove air bubbles. The degassed polyamic acid compositions were then coated onto glass substrates using a spin coater. They were then dried under a nitrogen atmosphere at 120°C for 30 minutes to prepare gel films. The gel films were then heated to 450°C at a rate of 2°C / min, heat-treated at 450°C for 60 minutes, and cooled to 30°C at a rate of 2°C / min to obtain polyimide films.

[0061] The polyimide film was then peeled off from the glass substrate by dipping in distilled water. The physical properties of the prepared polyimide film were measured using the following methods, and the results are shown in Table 2 below.

[0062] Experimental Example 1 - Corona Half-Life The corona half-life of the polyimides prepared in the above examples and comparative examples was measured according to JIS L 1094 standard using the following measuring equipment and conditions. -Analyzer:Static Honestmeter -Analysis condition: JIS L 1094 -Method of charging: DC10KV, HV Time 30s -Measurement end: 120s -Specific dimensions: 4.5*4.5cm

[0063] Experimental Example 2 - Volume Resistivity The volume resistivity of the polyimides prepared in the examples and comparative examples was measured according to ASTM D257 standard at a temperature of 23 (±2)°C and a relative humidity of 50% (about 45 (±5)%) using the following measuring equipment and conditions. 1.Analyzer 1) Equipment name: Resistance Meter 2) Manufacturer and model: Agilent / 4339B 3)Measurement range: 1kΩ to 16PΩ 4) Basic accuracy: ±0.6% 2.Analysis Method 1) Test condition -Temperature: 23±3℃ 2) Specimen -110×110mm Film 3) Test method: ASTM D257 4) Source Voltage: 500V 5)Load Scale:5kgf 6)Charge Time: 60 sec.

[0064] Experimental Example 3 - Viscosity The viscosity of the polyimide precursor compositions prepared in the examples and comparative examples was measured using a Haake Rheostress 600 under the conditions of a shear rate of 1 / s, a temperature of 23° C., and a plate gap of 1 mm.

[0065] Experimental Example 4 - Glass Transition Temperature For the polyimide films prepared in the examples and comparative examples, the point at which they suddenly expanded at 10° C. / min using TMA was measured as the on-set point.

[0066] Experimental Example 5-CTE Using a TA thermomechanical analyzer, model Q400, the polyimide film was cut into a width of 2 mm and a length of 10 mm. After that, the film was heated from room temperature to 500°C at a rate of 10°C / min while applying a tension of 0.05 N in a nitrogen atmosphere, and then cooled at a rate of 10°C / min, and the slope of the temperature gradient from 100°C to the Tg temperature was measured.

[0067] Experimental Example 6 - Thermal decomposition temperature (Td) of 1 wt% Using a TA thermogravimetric analyzer, model Q50, the polyimide film was heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, and then maintained at the same temperature for 30 minutes to remove moisture.Then, the film was heated to 600°C at a rate of 10°C / min, and the temperature at which a 1% weight loss occurred was measured.

[0068] [Table 2]

Claims

1. A polyimide comprising a cured product of a polyamic acid composition, the polyamic acid composition comprising a polyamic acid comprising a dianhydride monomer component and a diamine monomer component as polymerization units, and a solvent; wherein the solvent includes a first solvent and a second solvent that is a component different from the first solvent, the first solvent has a boiling point of 150°C or higher, and the second solvent has a boiling point lower than that of the first solvent; the second solvent is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the first solvent; The diamine monomer component includes p-phenylenediamine and 2,2'-dimethylbenzidine (M-TOLIDINE), the first solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; the second solvent is methanol; The cured product has a corona half-life of 80 seconds or more according to JIS L 1094 and a volume resistivity of 1.75×10 measured at 23° C. and 50% relative humidity according to ASTM D257. １６ Polyimide having a resistivity of Ω·cm or more.

2. 2. The polyimide according to claim 1, wherein the second solvent is contained in the range of 0.01 to 10% by weight in the total polyamic acid composition.

3. The polyimide according to claim 1 , wherein the dianhydride monomer comprises a monomer having an open ring structure that does not polymerize with a monomer other than the monomer contained in the polymerized unit.

4. The polyimide according to claim 1 , wherein the dianhydride monomer having an open ring structure participates in the imidization reaction.

5. 2. The polyimide of claim 1, wherein the dianhydride monomer comprises 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), oxydiphthalic dianhydride (ODPA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA), p-phenylenebis(trimellitate anhydride) (TAHQ), or 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA).

6. 2. The polyimide according to claim 1, wherein the solids content of the polyamic acid composition is in the range of 9 to 35%.

7. The polyamic acid composition was heated at a temperature of 23° C. and －１ 2. The polyimide of claim 1, wherein the viscosity measured at a shear rate of 1000 to 50,000 cP is in the range of 500 to 50,000 cP.

8. 2. The polyimide of claim 1, wherein the weight average molecular weight is in the range of 10,000 g / mol to 500,000 g / mol.

9. The polyimide of claim 1 , wherein the polyamic acid composition further comprises inorganic particles.

10. 2. The polyimide of claim 1, wherein the cured product has a CTE in the range of 40 ppm / °C or less.

11. The polyimide according to claim 1 , wherein the cured product has a glass transition temperature of 350° C. or higher.

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