Polyamic acid composition and polyimide containing the same

Abstract

The present application relates to a polyamic acid composition and a polyimide containing the same. 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 after curing, as well as a polyimide and a polyimide film produced therefrom.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0155540 filed on November 19, 2020, and all contents disclosed in the documents of the Korean patent application are included as part of this specification.

[0002] Technical field This application relates to a polyamic acid composition and a polyimide containing the same.

Background Art

[0003] Polyimide (PI) is a polymer material having thermal stability based on a rigid aromatic main chain, and has mechanical properties such as excellent strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring.

[0004] Furthermore, polyimide has attracted attention as a high-functional polymer material applicable in a wide range of industrial fields such as electronics, communication, and optics due to its excellent electrical properties such as insulation properties and low dielectric constant.

[0005] In recent years, as various electronic devices have become thinner, lighter, and smaller, many studies have been conducted to use a thin and flexible polyimide film as an insulating material for a circuit board or as a display substrate replacing a glass substrate for a display.

[0006] Particularly, in the case of a polyimide film used for a circuit board or a display substrate manufactured at a particularly high process temperature, it is necessary to ensure a higher level of dimensional stability, heat resistance, and mechanical properties.

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

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

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

[0010] However, the higher the molecular weight of the polyamic acid, the higher the viscosity of the polyamic acid solution in which the polyamic acid is dissolved in the solvent, the lower the fluidity, and the problem that the process handleability becomes extremely low occurs.

[0011] Also, in order to lower the viscosity of the polyamic acid while maintaining the molecular weight of the polyamic acid, a method of lowering the solid content and increasing the solvent content can be considered. However, in this case, since a large amount of solvent must be removed during the curing process, problems such as an increase in manufacturing cost and process time may occur.

[0012] Therefore, there is a high actual need for research on polyimide films that can maintain a low viscosity even when the solid content of the polyamic acid solution is high, satisfy processability, and simultaneously satisfy the heat resistance and mechanical properties of the polyimide manufactured therefrom.

Summary of the Invention

Problems to be Solved by the Invention

[0013] This application provides a polyamic acid composition having a high solid content concentration and low viscosity of the polyamic acid, and having excellent heat resistance, dimensional stability, and mechanical properties after curing, a polyimide, and a polyimide film manufactured therefrom.

Means for Solving the Problems

[0014] This application relates to a polyamic acid composition. The polyamic acid composition according to this application may contain a polyamic acid including a dianhydride monomer component and a diamine monomer component as polymerization units. Further, the polyamic acid composition may contain an organic solvent including a first solvent and a second solvent. The second solvent may have at least one or more polar functional groups selected from the group consisting of a hydroxy group, a carboxyl group, an alkoxy group, an ester group, and an ether group. The first solvent may be a component different from the second solvent. This application includes a first solvent and a second solvent that are different components from each other, and by limiting the types of functional groups of the second solvent, a polyamic acid composition having desired physical properties can be provided.

[0015] In one specific example, the dianhydride monomer may include a monomer having an unpolymerized and ring-opened structure in addition to the monomer contained in the polymerization unit. That is, a part of the dianhydride monomer may be contained in the polymerization unit, and a part may not be contained in the polymerization unit. The dianhydride monomer not contained in the polymerization unit may have a structure ring-opened by the organic solvent according to this application. The polyamic acid composition according to this application may exist in the form of an aromatic carboxylic acid having two or more carboxylic acids in a state where the dianhydride monomer is not polymerized. The aromatic carboxylic acid exists as a monomer before curing to lower the viscosity of the entire polyamic acid composition and improve processability. The aromatic carboxylic acid having two or more carboxylic acids is polymerized with a dianhydride monomer in the main chain after curing to increase the length of the entire polymer chain. Such a polymer can exhibit excellent heat resistance, dimensional stability, and mechanical physical properties.

[0016] Specifically, during the heat treatment for imidizing the polyamic acid composition into polyimide, the aromatic carboxylic acid having two or more carboxylic acids becomes a dianhydride monomer through a ring-closing dehydration reaction, reacts with the terminal amine groups of the polyamic acid chain or the polyimide chain, increasing 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.

[0017] In one example, as described above, the polyamic acid composition of the present application may contain a second solvent, and the second solvent may be contained within a range of 0.01 to 10% by weight in the total polyamic acid composition. The lower limit of the content of the second solvent may be, for example, 0.015% by weight, 0.03% by weight, 0.05% by weight, 0.08% by weight, 0.1% by weight, 0.3% by weight, 0.5% by weight, 0.8% by weight, 1% by weight or 2% by weight or more, and the upper limit may be, for example, 10% by weight, 9% by weight, 8% by weight, 7% by weight, 6% by weight, 5.5% by weight, 5.3% by weight, 5% by weight, 4.8% by weight, 4.5% by weight, 4% by weight, 3% by weight, 2.5% by weight, 1.5% by weight, 1.2% by weight, 0.95% by weight or 0.4% by weight or less. Further, the first solvent may be contained within a range of 60 to 95% by weight in the total polyamic acid composition. The lower limit of the content of the first solvent may be, for example, 65% by weight, 68% by weight, 70% by weight, 73% by weight, 75% by weight, 78% by weight or 80% by weight or more, and the upper limit may be, for example, 93% by weight, 90% by weight, 88% by weight, 85% by weight, 83% by weight, 81% by weight or 79% by weight or less. The polyamic acid composition according to the present application contains a dianhydride monomer component and a diamine monomer component, and the two monomers constitute polymerization units with each other. However, a part of the dianhydride monomer is ring-opened by the organic solvent and cannot participate in the polymerization reaction. The dianhydride monomer that is ring-opened without polymerization acts as a diluent monomer and can relatively lower the viscosity of the total polyamic acid composition. The dianhydride monomer having the ring-opened structure can participate in the reaction during the imidization reaction to realize the desired polyimide.

[0018] As described above, the polyamic acid composition of the present application may contain diamine monomers and dianhydride monomers as polymerization units. In this specification, the polyimide precursor composition may be used in the same meaning as the polyamic acid composition or the polyamic acid solution.

[0019] The dianhydride monomer that may be used in the production of the polyamic acid solution may be an aromatic tetracarboxylic dianhydride, and the aromatic tetracarboxylic dianhydride may be 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’-benzophenone tetracarboxylic dianhydride, 3,3’,4,4’-benzophenone tetracarboxylic 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)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, and the like.

[0020] The dianhydride monomer may be used alone or in combination of two or more thereof as necessary. For example, it may include pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), 4,4-(hexafluoroisopropylidene) diphthalic anhydride (6-FDA), or p-phenylenebis(trimellitate anhydride) (TAHQ).

[0021] 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 has excellent adhesive strength and can embody desired levels of mechanical properties.

[0022] In addition, the diamine monomer that can be used for the production of the polyamic acid solution is an aromatic diamine, and examples can be given by classification as follows.

[0023] 1) Diamines having one benzene nucleus in structure, such as 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (or DABA), etc., and diamines having a relatively rigid structure

[0024] 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-hexafluoropropene, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropene, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide,

[0025] 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,

[0026] 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-hexafluoropropene, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropene, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0027] 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), or 2,2-bis(trifluoromethyl)benzidine (TFDB).

[0028] In one specific example, the polyamic acid composition may contain a solid content of 9 to 35% by weight, 10 to 33% by weight, 10 to 30% by weight, 15 to 25% by weight, or 18 to 23% by weight based on the total weight. By relatively highly adjusting the solid content of the polyamic acid composition, the present application can maintain the physical properties after curing at a desired level, control the increase in viscosity, and prevent the increase in manufacturing cost and process time that requires removing a large amount of solvent during the curing process.

[0029] The polyamic acid composition of the present application may be a composition having low viscosity characteristics. The polyamic acid composition of the present application has a viscosity measured under the conditions of a temperature of 23°C and a shear rate of 1 s -1 of 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 1000 cP or more. The viscosity may be measured, for example, using a Rheostress 600 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. By adjusting the viscosity range, the present application can provide a precursor composition having excellent processability and form a film or substrate having desired physical properties when forming a film or substrate.

[0030] In one specific example, the polyamic acid composition of the present application may have a weight-average molecular weight after curing in the range 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 means the conversion numerical value with respect to standard polystyrene measured by GPC (Gel permeation Chromatograph).

[0031] The present application may include a first solvent and a second solvent. The solvent having the specific polar functional group described above can be defined as the second solvent.

[0032] In one example, the second solvent may have a solubility of less than 1.5 g / 100 g with respect to the dianhydride monomer. That is, the second solvent may have a solubility of less than 1.5 g / 100 g with respect to the dianhydride monomer. 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, 0.25 g / 100 g, 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 can provide a polyamic acid composition having desired physical properties by including a second solvent having a low solubility with respect to the dianhydride monomer contained in the polymerization unit or the unpolymerized dianhydride monomer. When the physical properties measured in the present application are physical properties affected by temperature, unless otherwise specified, they may be measured at room temperature of 23°C.

[0033] In a specific example of the present application, the first solvent may have a solubility of 1.5 g / 100 g or more with respect to the dianhydride monomer, for example. 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 first solvent may have a higher solubility than the second solvent.

[0034] 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 higher boiling point than the second solvent. The second solvent may have a boiling point within the range of 30°C or higher and less 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 or higher, 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 or lower. Also, 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. The present application can produce a polyimide having desired physical properties by using two solvents having different boiling points.

[0035] The first solvent according to the present application is not particularly limited as long as it can dissolve polyamic acid. In the case of the first solvent, it may also be a polar solvent. For example, the first solvent includes amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and 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.

[0036] As an example, the first solvent may be an aprotic polar solvent. The second solvent may be an aprotic polar solvent or a protic polar solvent. For example, the second solvent may include alcohol solvents such as methanol, ethanol, 1-propanol, butyl alcohol, isobutyl alcohol, or 2-propanol, ester solvents such as methyl acetate, ethyl acetate, or isopropyl acetate, carboxylic acid solvents such as formic acid, acetic acid, propionic acid, butyric acid, or lactic acid, ether solvents such as dimethyl ether, diethyl ether, diisopropyl ether, dimethoxyethane, or methyl t-butyl ether, dimethyl carbonate, metal methacrylate, or propylene glycol monomethyl ether acetate.

[0037] As described above, the present application may include the first solvent and the second solvent together. In this case, the first solvent may contain a higher content than the second solvent. Also, the second solvent may be contained in a ratio of 0.01 to 10 parts by weight with respect to 100 parts by weight of the first solvent. The lower limit of the content ratio 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.

[0038] The polyamic acid composition according to the present application may further contain inorganic particles. The inorganic particles may have an average particle size in the range of, for example, 5 to 80 nm. In a specific example, the lower limit may be 8 nm, 10 nm, 15 nm, 18 nm, 20 nm or 25 nm or less, and the upper limit may be, for example, 70 nm, 60 nm, 55 nm, 48 nm or 40 nm or less. In the present specification, the average particle size may be measured by D50 particle size analysis. By adjusting the particle size range, the present application can enhance the compatibility with polyamic acid and realize desired physical properties after curing.

[0039] The type of the 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. Further, the inorganic particles of the present application may contain a surface treatment agent on the surface. 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 (3-Aminopropyl)trimethoxy-silane (APTMS), and the thiol-based compound may include mercapto-propyl-trimethoxysilane (MPTMS), but is not limited thereto. Further, the surface treatment agent may include dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES) or tetraethoxysilane (TEOS). The present application may treat the surface of the inorganic particles with one kind of surface treatment agent or perform surface treatment through two kinds of surface treatment agents of different types. Further, the inorganic particles may be contained in the range of 1 to 20 parts by weight based on 100 parts by weight of the 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 blending the inorganic particles into the polyamic acid composition, the present application can improve the dispersibility and miscibility and realize the adhesiveness and heat-resistant durability after curing.

[0040] The polyamic acid composition may have a coefficient of thermal expansion (CTE) of 40 ppm / °C or less after curing. 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 coefficient of thermal expansion may be measured at 100 to 450 °C. The CTE may be measured using a thermomechanical analyzer Q400 model from TA Instruments. After manufacturing the polyimide into a film and cutting it into a width of 2 mm and a length of 10 mm, while applying a tension of 0.05 N in a nitrogen atmosphere, the temperature may be raised from room temperature to 500 °C at a rate of 10 °C / min, and then the slope in the range of 100 °C to 450 °C may be measured while cooling at a rate of 10 °C / min.

[0041] In addition, the polyamic acid composition may have an elongation of 10% or more after curing. In a specific example, it may be 12% or more, 13% or more, 15% or more, 18% or more, 20 to 60%, 20 to 50%, 20 to 40%, 20 to 38%, 22 to 36%, 24 to 33%, or 25 to 29%. The elongation may be measured by curing the polyamic acid composition into a polyimide film, cutting it into a width of 10 mm and a length of 40 mm, and then measuring the elongation by the ASTM D-882 method using an Instron5564UTM equipment from Instron.

[0042] In addition, the polyamic acid composition of the present application may have an elastic modulus within the range of 6.0 GPa to 11 GPa after curing. The lower limit of the elastic modulus 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. Further, the polyamic acid composition may have a tensile strength within the range of 300 MPa to 600 MPa after curing. 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 or more, and the upper limit may be, for example, 580 MPa, 570 MPa, 560 MPa, 545 MPa, 530 MPa or 500 MPa or less. The elastic modulus and the tensile strength may be measured by the ASTM D-882 method using an Instron 5564 UTM equipment of Instron after curing the polyamic acid composition to produce a polyimide film, cutting it into a width of 10 mm and a length of 40 mm. The Cross Head Speed at this time may be measured under the condition of 50 mm / min.

[0043] In one example, the polyamic acid composition according to the present application may have a glass transition temperature of 350 °C or higher after curing. 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 more. The glass transition temperature may be measured using TMA at a rate of 10 °C / min for the polyimide produced by curing the polyamic acid composition.

[0044] The polyamic acid composition according to the present application may have a thermal decomposition temperature of 500 °C or higher for 1% by weight after curing. The thermal decomposition temperature may be measured using the thermogravimetric analysis Q50 model of TA Instruments. In a specific example, after the polyimide obtained by curing the polyamic acid is heated to 150 °C at a rate of 10 °C / min in a nitrogen atmosphere, it is maintained isothermally for 30 minutes to remove moisture. Thereafter, it may be heated to 600 °C at a rate of 10 °C / min, and the temperature at which 1% weight loss occurs may 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 or higher, and the upper limit may be, for example, 800 °C, 750 °C, 700 °C, 650 °C or 630 °C or lower.

[0045] In addition, the polyamic acid composition according to the present application may have a light transmittance in the range of 50 to 80% at any 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 higher, and the upper limit may be, for example, 78%, 75%, 73%, 72%, 71%, 69%, 68%, 67%, 66%, 65%, or 64% or lower.

[0046] In addition, the present application relates to a method for producing a polyamic acid composition.

[0047] The manufacturing method is a method for manufacturing a polyamic acid composition containing a polyamic acid including a dianhydride monomer component and a diamine monomer component as polymerization units and an organic solvent containing at least polar functional groups, and may include a step of heating at at least 50°C or higher. 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, and the upper limit may be, 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. This application may include a step of mixing an organic solvent and a dianhydride monomer component before the heating step. This application may perform the heating step described above after the mixing, and thus, heating may be performed in a state where an organic solvent and a dianhydride monomer are included. By performing a heating step at a higher temperature than the conventional process in this application, a desired polyamic acid structure can be obtained, and after curing, the length of all polymer chains is increased, and such a polymer can exhibit excellent heat resistance, dimensional stability, and mechanical physical properties.

[0048] In a specific example, the manufacturing method of the polyamic acid composition of this application may have, for example, the following polymerization methods.

[0049] For example, (1) a method in which the total amount of the diamine monomer is put into a solvent, and then the dianhydride monomer is added so as to be substantially equimolar to the diamine monomer and polymerized.

[0050] (2) A method in which the total amount of the dianhydride monomer is put into a solvent, and then the diamine monomer is added so as to be substantially equimolar to the dianhydride monomer and polymerized.

[0051] (3) After putting a part of the diamine monomer component into a solvent, mixing a part of the dianhydride monomer component with respect to the reaction components at a ratio of about 95 to 105 mol%, then adding the remaining diamine monomer component, and then adding the remaining dianhydride monomer component, and polymerizing so that the diamine monomer and the dianhydride monomer are substantially equimolar.

[0052] (4) After putting the dianhydride monomer into a solvent, a part of the diamine compound components are mixed with the reaction components at a ratio of 95 to 105 mol%, then the other dianhydride monomer components are added, and then the remaining diamine monomer components are added, and polymerization is carried out so that the diamine monomer and the dianhydride monomer are substantially equimolar.

[0053] (5) A method in which in a solvent, a part of the diamine monomer components and a part of the dianhydride monomer components are reacted so that one of them is in excess to form a first composition, and further in another solvent, a part of the diamine monomer components and a part of the dianhydride monomer components are reacted so that one of them is in excess to form a second composition, and then the first and second compositions are mixed to complete the polymerization. At this time, when the diamine monomer components are in excess when forming the first composition, the dianhydride monomer components are in excess in the second composition, and when the dianhydride monomer components are in excess in the first composition, the diamine monomer components are in excess in the second composition. Examples include a method of mixing the first and second compositions so that all the diamine monomer components and dianhydride monomer components used in these reactions are substantially equimolar and then carrying out polymerization.

[0054] The polymerization method is not limited to the above examples, and it goes without saying that any known method can be used.

[0055] The step of producing the polyamic acid composition may be carried out at 30 to 80 °C.

[0056] In addition, this application relates to a polyimide containing a cured product of the polyamic acid composition. In addition, this application provides a polyimide film containing the polyimide. The polyimide film may be a polyimide film for a substrate, and in a specific example, it may be a polyimide film for a TFT substrate.

[0057] Furthermore, the present invention provides a method for manufacturing a polyimide film, which includes the steps of forming a film of a polyamic acid composition produced by the method for manufacturing the polyamic acid composition on a support, drying to produce a gel film, and curing the gel film.

[0058] Specifically, in the method for manufacturing a polyimide film of the present invention, the steps of forming a film of the polyimide precursor composition on a support, drying to produce a gel film, and curing the gel film may be carried out through the steps of drying the polyimide precursor composition formed on the support at a temperature of 20 to 120°C for 5 to 60 minutes to produce a gel film, heating the gel film from 30 to 500°C at a rate of 1 to 8°C / min, performing heat treatment at 450 to 500°C for 5 to 60 minutes, and cooling from 500 to 20°C at a rate of 1 to 8°C / min.

[0059] The step of curing the gel film may be carried out at 30 to 500°C. For example, the step of curing the gel film may be carried out 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.

[0060] The thickness of the polyimide film is characterized by being 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.

[0061] The support may be, for example, an inorganic substrate. Examples of the inorganic substrate include a glass substrate and a metal substrate, but it is preferable to use a glass substrate. The glass substrate may be a soda lime glass, a borosilicate glass, a non-alkali glass, etc., but is not limited thereto.

Advantages of the Invention

[0062] This application relates to a polyamic acid composition, a polyamic acid composition having a high solid content concentration of polyamic acid and a low viscosity, and having excellent heat resistance, dimensional stability and mechanical properties after curing, a polyimide and a polyimide film produced therefrom are provided.

Embodiments for Carrying Out the Invention

[0063] 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, but the scope of the present invention is not limited by the following Examples.

[0064] <Production of Polyamic Acid Solution> Example 1 While injecting nitrogen into a 500 m■ reactor equipped with a stirrer and a nitrogen injection / discharge pipe, after introducing N-methyl-pyrrolidone (NMP, 99.95 wt%) as the first solvent, further introducing methanol (MeOH) as the second solvent as an additive solvent at a ratio of 0.05 wt%, and stirring. After setting the temperature of the reactor to 70 °C, biphenyltetracarboxylic dianhydride (BPDA) was introduced as a dianhydride monomer and reacted. Next, the temperature was lowered to 30 °C under a nitrogen atmosphere, and para-phenylenediamine (PPD) was completely dissolved as a diamine monomer in this reaction solution and rapidly stirred. Thereafter, stirring was continued for 120 minutes while heating the temperature to 40 °C to produce a polyamic acid solution.

[0065] Example 2 A polyamic acid solution was produced in the same manner as in Example 1, except that the type and content ratio of the additive solvent were adjusted as shown in Table 1.

[0066] Examples 3 to 4 A polyamic acid solution was produced in the same manner as in Example 1, except that the types and content ratios of the monomers and additive solvents were adjusted as shown in Table 1.

[0067] Comparative Example 1 A polyamic acid solution was produced in the same manner as in Example 1, except that the additive solvent was excluded.

[0068] Comparative Example 2 A polyamic acid solution was produced in the same manner as in Example 1, except that the type of additive solvent was changed to Acetone.

[0069] Comparative Example 3 A polyamic acid solution was produced in the same manner as in Example 3, except that the type of additive solvent was changed to Toluene.

[0070] Comparative Example 4 A polyamic acid solution was produced in the same manner as in Example 4, except that the type of additive solvent was changed to Methyl ethyl ketone.

[0071] Comparative Example 5 A polyamic acid solution was produced in the same manner as in Example 4, except that the type of additive solvent was changed to Acetonitrile.

[0072] Comparative Example 6 A polyamic acid solution was produced in the same manner as in Example 1, except that the type of additive solvent was changed to Hexane.

[0073] [Table 1]

[0074] <Production of Polyimide for Physical Property Measurement> The polyamic acid compositions produced in the above Examples and Comparative Examples were defoamed by high-speed rotation at 1,500 rpm or more. Thereafter, the defoamed polyamic acid composition was applied to a glass substrate using a spin coater. Thereafter, a gel film was produced by drying in a nitrogen atmosphere at a temperature of 120°C for 30 minutes. The gel film was 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 a polyimide film.

[0075] Next, the polyimide film was peeled off from the glass substrate by dipping it in distilled water. The physical properties of the produced polyimide film were measured using the following method, and the results are shown in Table 2 below.

[0076] Experimental Example 1 - Thickness The thickness of the produced polyimide film was measured using an Anritsu film thickness tester (Electric Film thickness tester).

[0077] Experimental Example 2 - Viscosity For the polyimide precursor compositions produced in the examples and comparative examples, the viscosity was measured using a Haake Rheostress 600 at a shear rate of 1 / s, a temperature of 23 °C, and a plate gap condition of 1 mm.

[0078] Experimental Example 3 - CTE Using a TA thermomechanical analyzer Q400 model, after cutting the polyimide film into a width of 2 mm and a length of 10 mm, while applying a tension of 0.05 N in a nitrogen atmosphere, the temperature was raised from room temperature to 500 °C at a rate of 10 °C / min, and then cooled at a rate of 10 °C / min while measuring the slope in the section from 100 °C to the Tg temperature.

[0079] Experimental Example 4 - Glass Transition Temperature For the polyimide films produced in the examples and comparative examples, the point where rapid expansion occurred under the condition of 10 °C / min using TMA was measured as the On-set point.

[0080] Experimental Example 5 - Elongation After cutting the polyimide film into a width of 10 mm and a length of 40 mm, the elongation was measured by the ASTM D - 882 method using an Instron 5564 UTM equipment of Instron.

[0081] Experimental Example 6 - Elastic Modulus and Tensile Strength After cutting the polyimide film into a width of 10 mm and a length of 40 mm, the modulus and tensile strength were measured by the ASTM D-882 method using an Instron 5564 UTM equipment from Instron. The Cross Head Speed at this time was measured under the condition of 50 mm / min.

[0082] Experimental Example 7 - Appearance State of Film As a result of visually checking the polyimide films produced in the examples and comparative examples, when there was no generation of bubbles in the film and the appearance was good, it was classified as O; when a large amount of bubbles were generated (three or more bubbles were generated), it was classified as X; when two or fewer bubbles were generated, it was classified as △.

[0083]

Table 2

Claims

1. A polyimide containing a cured product of a polyamic acid composition, wherein the polyamic acid composition contains a polyamic acid containing a dianhydride monomer component and a diamine monomer component as polymerization units, and an organic solvent containing a first solvent and a second solvent, the second solvent has at least one or more polar functional groups selected from the group consisting of a hydroxy group, a carboxyl group, an alkoxy group, an ester group, and an ether group, and the first solvent is a component different from the second solvent, the second solvent is contained in an amount of 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the first solvent, the cured product has a CTE of 3.5 to 40 ppm / °C, a glass transition temperature of 350°C or higher, an elongation in the range of 10% or more, and an elastic modulus in the range of 6.0 GPa to 11 GPa, a polyimide.

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 contains a monomer having an unpolymerized ring-opened structure in addition to the monomer contained in the polymerization unit.

4. The polyimide according to claim 3, wherein the dianhydride monomer having a ring-opened structure participates in the reaction during the imidization reaction.

5. The diamine monomer is 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) or 2,2-bis(trifluoromethyl)benzidine (TFDB), the polyimide according to claim 1.

6. The dianhydride monomer is the polyimide according to claim 1, including pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), 4,4-(hexafluoroisopropylidene) diphthalic anhydride (6-FDA), or p-phenylenebis(trimellitate anhydride) (TAHQ).

7. The polyimide according to claim 1, wherein the first solvent has a higher boiling point than the second solvent.

8. The polyimide according to claim 1, wherein the solid content of the polyamic acid composition is in the range of 9 to 35% by weight.

9. The viscosity of the polyamic acid composition measured at a temperature of 23°C and a shear rate of 1 s －１ is in the range of 500 to 50,000 cP, and the polyimide according to claim 1.

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

11. The polyimide according to claim 1, wherein the polyamic acid composition further contains inorganic particles.

12. A polyimide film for a substrate containing the polyimide according to claim 1.

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