Polyamic acid composition and polyimide containing the same

Abstract

The present invention 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 a polyimide and 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. 10-2020-0155541, filed on November 19, 2020, and all of the contents disclosed in the document of the Korean patent application are incorporated herein by reference.

[0002] Technical Field The present invention 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 excellent mechanical properties such as strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring.

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

[0005] Recently, with the thinning, lightening, and miniaturization of various electronic devices, many studies have been conducted to use a thin and flexible polyimide film as an insulating material for a circuit board or a display substrate that can replace a glass substrate for a display.

[0006] In particular, 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] As an example of a method for ensuring such physical properties, a method of increasing the molecular weight of polyimide can be taken.

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

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

[0010] However, as the molecular weight of polyamic acid increases, the viscosity of the polyamic acid solution in which polyamic acid is dissolved in a solvent increases, fluidity decreases, and a problem occurs where the process handleability becomes extremely low.

[0011] Also, in order to reduce the viscosity of polyamic acid while maintaining its molecular weight, a method of reducing the solid content and increasing the solvent content can be considered. However, in this case, a large amount of solvent must be removed during the curing process, resulting in problems of increased manufacturing costs and process time.

[0012] Therefore, there is a high need for research on polyimide films that can simultaneously satisfy the heat resistance and mechanical properties of the polyimide to be produced in the future while maintaining a low viscosity and meeting processability even when the solid content of the polyamic acid solution is high.

Summary of the Invention

Problems to be Solved by the Invention

[0013] The present invention aims to provide a polyamic acid composition having a high solid concentration and low viscosity of polyamic acid, and having excellent heat resistance, dimensional stability, and mechanical properties after curing, a polyimide produced therefrom, and a polyimide film.

Means for Solving the Problems

[0014] The present invention relates to a polyamic acid composition. The polyamic acid composition according to the present invention may contain a polyamic acid containing a dianhydride monomer component and a diamine monomer component as polymerization units. Further, the polyamic acid composition may contain a solvent, and the solvent may contain a second solvent having 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 invention can provide a polyamic acid composition having desired physical properties by containing a second solvent having a low solubility with respect to the dianhydride monomer contained as a polymerization unit or the non-polymerized dianhydride monomer. When the physical property measured in the present invention is a physical property affected by temperature, unless otherwise specified, it may be measured at room temperature of 23°C.

[0015] The polyamic acid composition of the present invention may further contain a first solvent which is a component different from the second solvent. 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 solubility of the first solvent may be even higher than that of the second solvent.

[0016] 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. 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 invention can produce a polyimide having desired physical properties by using two solvents having different boiling points.

[0017] In one example, 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. The present invention can provide a polyamic acid composition having a desired physical property by including a first solvent and a second solvent that are different components from each other and limiting the types of functional groups of the second solvent. The solvent may be an organic solvent, but is not limited thereto. The second solvent may be contained in the entire polyamic acid composition in the range of 0.01 to 10% by weight. 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 in the entire polyamic acid composition in the range of 60 to 95% by weight. 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 invention includes 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 monomers cannot participate in the polymerization reaction by ring-opening with the organic solvent. The dianhydride monomers that have undergone ring-opening without polymerization act as diluent monomers and can relatively lower the viscosity of the entire polyamic acid composition. The dianhydride monomers having the ring-opening structure can participate in the reaction during the imidization reaction to embody the desired polyimide.

[0018] As described above, the dianhydride monomer may contain a monomer having a ring-opening structure that does not polymerize 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 a second solvent. The polyamic acid composition according to the present invention may exist in the form of an aromatic carboxylic acid having two or more carboxylic acids in a state where the dianhydride monomer does not polymerize. The aromatic carboxylic acid exists as a monomer before curing, and the viscosity of the entire polyamic acid composition can be reduced and the processability can be improved. The aromatic carboxylic acid having two or more carboxylic acids polymerizes with a dianhydride monomer in the main chain after curing, thereby increasing the length of the entire polymer chain. Such a polymer can exhibit excellent heat resistance, dimensional stability, and mechanical properties.

[0019] Specifically, in the polyamic acid composition, during the heat treatment for imidization to polyimide, the aromatic carboxylic acid having two or more carboxylic acids becomes a dianhydride monomer through a ring-closing dehydration reaction, and 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 the thermal stability at high temperature of the produced polyimide film can be improved, and the mechanical properties at room temperature can be improved.

[0020] As described above, the polyamic acid composition of the present invention may contain a diamine monomer and a dianhydride monomer as polymerization units. In the present specification, the polyimide precursor composition can be used in the same meaning as the polyamic acid composition or the polyamic acid solution.

[0021] The dianhydride monomer that can be used in the production of 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 dianhydride (or ODPA), diphenylsulfone-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’-benzophenone tetracarboxylic acid dianhydride, 3,3’,4,4’-benzophenone tetracarboxylic acid dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimeric acid monoester anhydride), p-biphenylenebis(trimeric acid monoester 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-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, 4,4’-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, etc. can be exemplified.

[0022] The dianhydride monomer can be used alone or in combination of two or more as needed. 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).

[0023] In a specific example of the present invention, 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 invention can achieve both a desired level of mechanical properties while having excellent adhesion.

[0024] In addition, the diamine monomer that can be used in the production of the polyamic acid solution is an aromatic diamine and can be classified and exemplified as follows. 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; 2) Diamines having two benzene nuclei in structure, such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl) sulfide, 4,4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide; 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; 4) Diamines having four benzene nuclei in structure, such as 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0025] In one embodiment, the diamine monomer according to the present invention 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).

[0026] 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 relatively highly adjusting the solids content of the polyamic acid composition of the present invention, while maintaining the physical properties after curing at the target level, it is possible to control the increase in viscosity and prevent the increase in manufacturing costs and process time that would otherwise be required to remove a large amount of solvent during the curing process.

[0027] The polyamic acid composition of the present invention may be a composition having low viscosity characteristics. The polyamic acid composition of the present invention has a viscosity measured under the conditions of a temperature of 23°C and a shear rate of 1 s -1 that 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 1000 cP or more. The viscosity may be measured using, for example, 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 within the above range, the present invention provides a precursor composition having excellent processability and can form a film or substrate having the desired physical properties when forming a film or substrate.

[0028] In one specific example, the polyamic acid composition of the present invention 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 invention, the term weight average molecular weight means the conversion numerical value with respect to standard polystyrene measured by GPC (Gel permeation Chromatograph).

[0029] The first solvent according to the present invention is not particularly limited as long as it is a solvent in which polyamic acid can be dissolved. Also in the case of the first solvent, it may be a polar solvent. For example, examples of the first solvent include 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.

[0030] As one 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, methyl methacrylate, or propylene glycol monomethyl ether acetate.

[0031] The present invention may contain both the first solvent and the second solvent. In this case, the first solvent may be contained in a larger content than the second solvent. Further, the second solvent may be contained in a proportion of 0.01 to 10 parts by weight with respect to 100 parts by weight of the first solvent. The lower limit of the proportion of the content may be, for example, 0.02 part by weight, 0.03 part by weight, 0.04 part by weight, 0.1 part by weight, 0.3 part by weight, 0.5 part by weight, 0.8 part 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.

[0032] The polyamic acid composition according to the present invention may further contain inorganic particles. The inorganic particles may, for example, have an average particle size in the range of 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. The present invention can enhance the compatibility with polyamic acid and realize the desired physical properties after curing by adjusting the range of the particle size.

[0033] 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 invention 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 invention can treat the surface of the inorganic particles with one kind of surface treatment agent or perform surface treatment using two kinds of surface treatment agents of different types from each other. 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. The present invention can improve the dispersibility and miscibility and realize the adhesiveness and heat-resistant durability after curing by blending the inorganic particles into the polyamic acid composition.

[0034] 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 can be measured using a TA Instruments thermomechanical analyzer, model Q400. 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 is 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 temperature range from 100°C to 450°C.

[0035] 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 can be measured by the ASTM D-882 method using an Instron 5564 UTM instrument from Instron after curing the polyamic acid composition into a polyimide film and cutting it into a width of 10 mm and a length of 40 mm.

[0036] In addition, the polyamic acid composition of the present invention 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 can 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 and then cutting it into a width of 10 mm and a length of 40 mm. The Cross Head Speed at this time can be measured under the condition of 50 mm / min.

[0037] In one exemplary embodiment, the polyamic acid composition according to the present invention may have a glass transition temperature of 300 °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 320 °C, 330 °C, 340 °C, 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. The glass transition temperature can be measured for the polyimide produced by curing the polyamic acid composition using TMA under the condition of 10 °C / min.

[0038] The polyamic acid composition according to the present invention may have a 1% weight thermal decomposition temperature of 500 °C or higher after curing. The thermal decomposition temperature can be measured using the thermogravimetric analysis Q50 model of TA Instruments. In a specific example, after heating the polyimide obtained by curing the polyamic acid to 150 °C at a rate of 10 °C / min in a nitrogen atmosphere, the temperature is maintained isothermally for 30 minutes to remove moisture. Then, the temperature can be raised to 600 °C at a rate of 10 °C / min to measure the temperature at which a 1% weight loss occurs. 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.

[0039] Also, the polyamic acid composition according to the present invention may have a light transmittance in the range 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 higher, and the upper limit may be, for example, 78%, 75%, 73%, 72%, 71%, 69%, 68%, 67%, 66%, 65% or 64% or lower.

[0040] The present invention also relates to a method for producing a polyamic acid composition, which may be the method for producing the polyamic acid composition described above.

[0041] The manufacturing method 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. The present invention may include a step of mixing an organic solvent and a dianhydride monomer component before the heating step. In the present invention, the heating step described above may be performed after the mixing, and thus, heating may be performed in a state containing an organic solvent and a dianhydride monomer. By performing a heating step at a higher temperature than the conventional process, the present invention can have a target polyamic acid structure, and after curing, the length of the entire polymer chain can be increased, and such a polymer can exhibit excellent heat resistance, dimensional stability, and mechanical properties.

[0042] In a specific example, the manufacturing method of the polyamic acid composition of the present invention can have, for example, the following polymerization method. 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; (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; (3) After putting a part of the components of the diamine monomer into a solvent, mixing a part of the components of the dianhydride monomer at a ratio of about 95 to 105 mol% with respect to the reaction components, adding the remaining diamine monomer component, and then continuously adding the remaining dianhydride monomer component so that the diamine monomer and the dianhydride monomer are substantially equimolar and polymerizing; (4) A method of polymerization in which a dianhydride monomer is placed in a solvent, and then a part of the components of the diamine compound is mixed with the reaction components at a ratio of 95 to 105 mol%, followed by adding another dianhydride monomer component, and then adding the remaining diamine monomer component to achieve substantially equimolar amounts of the diamine monomer and the dianhydride monomer; (5) A method in which a part of the diamine monomer component and a part of the dianhydride monomer component in one of the solvents are reacted so that one of them is in excess to form a first composition, and a part of the diamine monomer component and a part of the dianhydride monomer component in another solvent 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 forming the first composition, if the diamine monomer component is in excess, in the second composition, the dianhydride monomer component is in excess; if the dianhydride monomer component is in excess in the first composition, in the second composition, the diamine monomer component is in excess. The first and second compositions are mixed so that the total diamine monomer component and dianhydride monomer component used in these reactions are substantially equimolar for polymerization. Examples of such methods include this.

[0043] The polymerization method is not limited only to the above examples, and of course, any known method can be used.

[0044] The step of producing the polyamic acid composition may be carried out at 30 to 80°C.

[0045] The present invention also relates to a polyimide containing a cured product of the polyamic acid composition. The present invention also 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.

[0046] In addition, the present invention provides a method for producing a polyimide film, which includes a step of forming a polyamic acid composition produced by the method for producing the polyamic acid composition on a support, drying it to produce a gel film, and curing the gel film.

[0047] Specifically, in the method for producing a polyimide film of the present invention, the step of forming the polyimide precursor composition on a support, drying it to produce a gel film, and curing the gel film may be carried out through a process 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 it from 500 to 20°C at a rate of 1 to 8°C / min.

[0048] 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.

[0049] The polyimide film is characterized in that its thickness is 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.

[0050] 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. For the glass substrate, soda lime glass, borosilicate glass, alkali-free glass, etc. can be used, but it is not limited thereto.

Advantages of the Invention

[0051] The present invention relates to a polyamic acid composition, a polyamic acid composition having a high solid content concentration, a low viscosity, and 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

[0052] Hereinafter, the present invention will be described in more detail 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 by the Examples presented below.

[0053] <Production of Polyamic Acid Solution> Example 1 While injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection / discharge pipe, N-methyl-pyrrolidone (NMP) was introduced as the first solvent, and then methanol (MeOH) as the second solvent was introduced at a ratio of 1 wt% (99 wt% NMP) as an additional solvent and stirred. 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. Then, while heating at a temperature of 40°C, stirring was continued for 120 minutes to produce a polyamic acid solution.

[0054] Examples 2 to 6 A polyamic acid solution was produced in the same manner as in Example 1, except that the ratio of the monomers and the content, and the additional solvent were adjusted as shown in Table 1.

[0055] Comparative Examples 1 to 4 A polyamic acid solution was produced in the same manner as in Example 1, except that the ratio of the monomers and the content, and the additional solvent were adjusted as shown in Table 1.

[0056]

Table 1

[0057] The solubility of the solvent was measured by the degree to which BPDA and / or PMDA used in the examples and comparative examples dissolved in each solvent.

[0058] <Production of Polyimide for Physical Property Measurement> The polyamic acid compositions produced in the examples and comparative examples were defoamed through 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 at a temperature of 120°C for 30 minutes under a nitrogen atmosphere, the temperature of the gel film was raised to 450°C at a rate of 2°C / min, heat treatment was performed at 450°C for 60 minutes, and the film was cooled to 30°C at a rate of 2°C / min to obtain a polyimide film.

[0059] Thereafter, it was dipped in distilled water to peel the polyimide film from the glass substrate. The physical properties of the produced polyimide film were measured using the following method, and the results are shown in Table 2 below.

[0060] Experimental Example 1 - Viscosity For the polyimide precursor compositions produced in the examples and comparative examples, the viscosity was measured using a Rheostress 600 from Haake at a shear rate of 1 / s, a temperature of 23°C, and a plate gap of 1 mm.

[0061] Experimental Example 2 - CTE Using a Q400 model thermomechanical analyzer from TA Instruments, 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 under a nitrogen atmosphere, the temperature was raised from room temperature to 500°C at a rate of 10°C / min, and then while cooling at a rate of 10°C / min, the slope in the section from 100°C to the Tg temperature was measured.

[0062] Experimental Example 3 - Glass Transition Temperature For the polyimide films produced in the examples and comparative examples, the point at which they rapidly expand under the condition of 10 °C / min using TMA was measured as the On-set point.

[0063] Thermal decomposition temperature (Td) of Experiment Example 4 - weight percentage Using the thermogravimetric analysis Q50 model of TA Instruments, the polyimide film was heated to 150 °C at a rate of 10 °C / min under a nitrogen atmosphere, and then held isothermally for 30 minutes to remove moisture. Thereafter, it was heated to 600 °C at a rate of 10 °C / min, and the temperature at which a 1% weight loss occurred was measured.

[0064] Experiment Example 5 - Light transmittance For the polyimide film produced above, the light transmittance was measured in the wavelength range of 380 nm to 780 nm using a UV-Vis Spectrometer, and the average value was calculated.

[0065] Experiment Example 5 - Solubility after polymerization reaction For the polyamic acid compositions produced in the examples and comparative examples, the solubility was observed. When it dissolved uniformly without precipitation, it was classified as O, and when precipitation occurred, it was classified as X.

[0066] [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 a solvent, the solvent contains a first solvent having a solubility of 1.5 g / 100 g or more with respect to the dianhydride monomer, and a second solvent that is isopropyl acetate, dimethyl carbonate, or 1,2-dimethoxyethane, the second solvent is contained in an amount of 0.01 to 5 parts by weight with respect to 100 parts by weight of the first solvent, the cured product has a light transmittance of 65 to 80% in any one wavelength band in the visible light region of 380 to 780 nm, the polyimide, wherein the cured product has a coefficient of thermal expansion (CTE) of 8.7 to 30 ppm / °C.

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 entire polyamic acid composition.

3. The polyimide according to claim 1, wherein the dianhydride monomer contains a monomer having a ring-opening structure that does not polymerize other than the monomers contained in the polymerization units.

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

5. The polyimide according to claim 1, wherein the diamine monomer contains 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).

6. The dianhydride monomer is the polyimide according to claim 1, comprising 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 polyamic acid composition has a solid content in the range of 9 to 35%.

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

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

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

11. The polyimide according to claim 1, wherein the cured product has a glass transition temperature after curing in the range of 300°C or higher.

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

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