A polyamic acid composition and a polyimide comprising the same.

Abstract

This invention relates to a polyamic acid composition and a polyimide comprising the polyamic acid, wherein the polyamic acid has a high solids content concentration and low viscosity, and after curing, a polyamic acid composition with excellent heat resistance, dimensional stability and mechanical properties is prepared, as well as polyimides and polyimide films prepared therefrom.

Description

[0001] Cross-referencing and related applications

[0002] This invention claims priority to Korean Patent Application No. 10-2020-0155541, dated November 19, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to a polyamic acid composition and a polyimide comprising the same. Background Technology

[0004] Polyimide (PI) is a thermally stable polymer material based on a rigid aromatic backbone. Its chemical stability based on the imide ring results in excellent mechanical properties, such as strength, chemical resistance, weather resistance, and heat resistance.

[0005] In addition, polyimide has insulating properties and excellent electrical properties, such as a low dielectric constant, making it a highly attractive high-performance polymer material suitable for a wide range of industrial applications, such as electronics, communications, and optics.

[0006] Recently, various electronic devices have tended to be thinner, lighter, and smaller, so much research has been conducted. The present invention aims to use lightweight and highly flexible polyimide film as an insulating material for circuit boards or a display substrate that can replace the glass substrate of a display.

[0007] In particular, for polyimide films used in circuit boards or display panels manufactured at high process temperatures, it is necessary to ensure a higher level of dimensional stability, heat resistance and mechanical properties.

[0008] One method to ensure this property is to increase the molecular weight of the polyimide.

[0009] The more imide groups a polyimide film contains, the higher its heat resistance and mechanical properties. The longer the polymer chain, the greater the proportion of imide groups. Therefore, preparing high-molecular-weight polyimides is beneficial for ensuring these properties. To prepare high-molecular-weight polyimides, the precursor polyimide is typically prepared to a high molecular weight, and then imidized through heat treatment.

[0010] However, the higher the molecular weight of polyimide, the higher the viscosity of the polyimide solution in the solvent, resulting in reduced fluidity and extremely low process operability.

[0011] In addition, in order to reduce the viscosity of polyimide while maintaining its molecular weight, one could consider reducing the solid content and increasing the solvent content. However, in this case, the manufacturing cost and processing time may increase because a large amount of solvent needs to be removed during the curing process.

[0012] Therefore, there is an urgent need to study polyimide films that maintain low viscosity even when the solid content of the polyimide solution is high, so as to meet the processability requirements, while also satisfying the heat resistance and mechanical properties of the polyimide prepared therefrom. Summary of the Invention

[0013] The purpose of this invention is to provide a polyamic acid composition and polyimide and polyimide film prepared therefrom, wherein the polyamic acid has a high solids content concentration and low viscosity, and exhibits excellent heat resistance, dimensional stability and mechanical properties after curing.

[0014] The present invention aims to provide a polyamic acid composition comprising a dianhydride monomer component and a diamine monomer component as polymerizing units. Furthermore, the polyamic acid composition contains a solvent, said solvent including a second solvent having a solubility of less than 1.5 g / 100 g relative to the dianhydride monomer. That is, the second solvent has a solubility of less than 1.5 g / 100 g relative to the dianhydride monomer. The upper limit of the above solubility range is, for example, below 1.3g / 100g, 1.2g / 100g, 1.1g / 100g, 1.0g / 100g, 0.9g / 100g, 0.8g / 100g, 0.7g / 100g, 0.6g / 100g, 0.5g / 100g, 0.4g / 100g, 0.3g / 100g, 0.25g / 100g, 0.23g / 100g, 0.21g / 100g, 0.2g / 100g, or 0.15g / 100g, and the lower limit of the above solubility range is above 0g / 100g, 0.01g / 100g, 0.05g / 100g, 0.08g / 100g, 0.09g / 100g, or 0.15g / 100g. This invention includes a second solvent having low solubility for dianhydride monomers containing polymerization units or unpolymerized dianhydride monomers, which can provide polyamic acid compositions with the desired physical properties. If the physical properties measured in this invention are temperature-dependent, they may be measured at room temperature (23°C), unless otherwise specified.

[0015] The polyamic acid composition of the present invention further includes a first solvent with a composition different from that of the second solvent. The first solvent is, for example, having a solubility of 1.5 g / 100 g or more relative to the dianhydride monomer. The lower limit of the solubility can be: 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 can be: 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. The first solvent may have higher solubility than the second solvent.

[0016] In one specific example, the boiling point of the first solvent can reach 150°C or higher, and the boiling point of the second solvent can be lower than that of the first solvent. The boiling point of the second solvent can be in the range of 30°C or higher and below 150°C. The lower limit of the boiling point of the first solvent can be, for example, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, or 201°C or higher, and the upper limit of the boiling point of the first solvent can be, for example, 500°C, 450°C, 300°C, 280°C, 270°C, 250°C, 240°C, 230°C, 220°C, 210°C, or below 205°C. Furthermore, the lower limit of the boiling point of the second solvent can 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 can 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. This invention, by using two solvents with different boiling points, can manufacture polyimides with target properties.

[0017] In one specific example, the second solvent has at least one polar functional group selected from the group consisting of hydroxyl, carboxyl, alkoxy ester, and ether groups, and the first solvent is a component different from the second solvent. The polyamic acid composition provided by the present invention, by containing two different components—a first solvent and a second solvent—and by limiting the type of the second solvent, can provide the desired physical properties. The solvent can be an organic solvent, but is not limited thereto. The content of the second solvent is 0.01 to 10% by weight of the total amount of the polyamic acid composition. The lower limit of the content of the second solvent mentioned above can 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. The upper limit of the content of the second solvent mentioned above can 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. Furthermore, the polyamic acid composition includes a first solvent, wherein the content of the first solvent accounts for 60 to 95 wt% of the total amount of the polyamic acid composition. The lower limit of the content of the first solvent mentioned above can be, for example, 65% by weight or more, 68% by weight or more, 70% by weight or more, 73% by weight or more, 75% by weight or more, 78% by weight or more, or 80% by weight or more. The upper limit of the content of the first solvent mentioned above can be, for example, 93% by weight or less, 90% by weight or less, 88% by weight or less, 85% by weight or less, 83% by weight or less, 81% by weight or less, or 79% by weight or less. The polyamic acid composition of the present invention contains a dianhydride monomer component and a diamine monomer component. The two monomers constitute a polymerization unit with each other. However, a portion of the dihydroxy monomer is ring-opened by the organic solvent mentioned above and therefore cannot participate in the polymerization reaction. The unpolymerized ring-opened dianhydride monomer acts as a diluent monomer, which can control the viscosity of the entire polyamic acid composition to be relatively low. The dianhydride monomer having the above-mentioned ring-opening structure can participate in the acylamination reaction, thereby achieving the desired polyimide.

[0018] As described above, the dianhydride monomers contain monomers with open-ring structures in addition to monomers that serve as polymerization units. That is, regarding the dianhydride monomers, a portion is included in the polymerization units, and a portion may not be included. The monomers not included in the polymerization units have an unpolymerized open-ring structure in the second organic solvent of the present invention. According to the polyamic acid composition of the present invention, when the dianhydride monomers do not participate in the polymerization reaction, it contains aromatic carboxylic acids having two or more carboxylic acids, and these aromatic carboxylic acids exist as monomers before curing, thereby reducing the viscosity of the entire polyamic acid composition and improving processability. After curing, the aromatic carboxylic acids having two or more carboxylic acids polymerize onto the polymer backbone as dianhydride monomers, thereby increasing the length of the entire polymer chain, and this polymer can achieve excellent heat resistance, dimensional stability, and mechanical properties.

[0019] Specifically, in the above-mentioned polyamic acid composition, during the heat treatment of polyimide formation, aromatic carboxylic acids having two or more carboxylic acids become dianhydride monomers through a ring-closing dehydration reaction, thereby reacting with the terminal amine groups of the polyamic acid chain or polyimide chain to increase the polymer chain length, thereby improving the dimensional stability and thermal stability of the polyimide film prepared therefrom, and improving the mechanical properties at room temperature.

[0020] As described above, the polyamic acid composition of the present invention contains dianhydride monomer components and diamine monomer components as polymerization units. In the present invention, the term "precursor composition" has the same meaning as "polyamic acid composition" or "polyamic acid composition solution".

[0021] The dianhydride monomers that can be used to prepare polyamic acid solutions can be aromatic tetracarboxylic dianhydrides. Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or α-BPDA), phthalic anhydride oxidized (or ODPA), diphenyl sulfone-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'-diphenyltetracarboxylic dianhydride (or BTDA), bis(3,4-diphenyl... Carboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene dianhydride (trimethoxymethyl ester anhydride), p-biphenylcarboxylic acid (trimethoxymethyl ester 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)phenyl dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phenyl 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-hexafluoroisopropyl)dibenzoic acid dianhydride, etc.

[0022] The aforementioned dianhydride monomers can be used alone or in combination with two or more monomers as needed. The dianhydride monomers are pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA), 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), oxydiphenyl dianhydride (ODPA), hexafluorodianhydride (6-FDA, 4,4'-(Hexafluoroisopropylidene)diphthalic anhydride), or p-phenylene-bis(phenyltriterpenoid) dianhydride (TAHQ).

[0023] In a specific example of the present invention, the aforementioned dianhydride monomer may include a dianhydride monomer having one benzene ring and a dianhydride monomer having two or more benzene rings. The content of the aforementioned dianhydride monomer having one benzene ring and the dianhydride monomer having two or more benzene rings is respectively in a molar ratio of 20-60 mol% and 40-90 mol%; 25-55 mol% and 45-80 mol%; or 35-53 mol% and 48-75 mol%. The present invention includes the aforementioned dianhydride monomer, which exhibits excellent adhesion while achieving the target level of mechanical properties.

[0024] In addition, the diamine monomers that can be used to prepare polyamic acid solutions are aromatic diamines, which can be classified and exemplified as follows.

[0025] 1) Diamines with relatively rigid structures, such as diamines with a benzene ring in their structure, such as 1,4-diaminobenzene (or p-phenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (or DABA), etc.

[0026] 2) Diamines with two benzene rings in their structure, such as diaminodiphenyl ethers like 4,4'-diaminodiphenyl ether (or diphenylamine oxide, ODA) and 3,4'-diaminodiphenyl ether; 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminodiphenyl, 2,2'-dimethyl-4,4'-diaminodiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenyl Benzene, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzamide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-toluidine), 2,2'-dimethylbenzidine (or m-toluidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenylmethane Ethers, 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, 3,3'-diaminodiphenyl sulfone, 4'-diaminodiphenyl sulfone, 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(3-aminophenyl)-1,1,3,3,3-hexafluoropropane, 2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, etc.;

[0027] 3) Diamines with three benzene rings in their 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, and 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone. 3,3'-Diamino-4,4'-bis(4-phenoxy)benzophenone, 1,3-bis(3-aminophenyl sulfide)benzene, 1,3-bis(4-aminophenyl sulfide)benzene, 1,4-bis(4-aminophenyl sulfide)benzene, 1,3-bis(3-aminophenyl sulfone), 1,3-bis(4-aminophenyl sulfone), 1,4-bis(4-aminophenyl sulfone)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, etc.;

[0028] 4) Diamines with four benzene rings in their 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- ...[3-(3-)phenyl [-aminophenoxy)phenyl]one, bis[3-(4-aminophenoxy)phenyl]one, bis[4-(3-aminophenoxy)phenyl]one, bis[4-(4-aminophenoxy)phenyl]one, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfonate, bis[3-(4-aminophenoxy)phenyl]sulfonate, 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-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-)phenyl]propane [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-aminophenoxy]phenyl-1,1,1,3,3,3-hexafluoropropane, etc.

[0029] In one specific example, the diamine monomer according to the present invention includes: 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-diaminobenzoylaniline (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).

[0030] In one specific example, the solid content of the polyamic acid composition, based on total weight, is 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. By controlling the solid content of the aforementioned polyamic acid composition to be relatively high, the present invention maintains the physical properties after curing while controlling the increase in viscosity, thereby preventing an increase in manufacturing costs and processing time that would otherwise require the removal of large amounts of solvent during the curing process.

[0031] The polyimide composition of the present invention may be a composition with low viscosity properties. The polyimide composition of the present invention exhibits low viscosity at 23°C and 1 second. -1 The viscosity measured under shear rate conditions may be below 50,000 cP, below 40,000 cP, below 30,000 cP, below 20,000 cP, below 10,000 cP, or below 9,000 cP. The lower limit is not particularly limited, but may be above 500 cP or above 1,000 cP. The above viscosity can be measured, for example, using a Haake Rheostress 600, or under conditions of a shear rate of 1 / s, a temperature of 23°C, and a plate gap of 1 mm. By adjusting the above viscosity range, the present invention can provide precursor compositions with good processability, and thin films or substrates with the physical properties required for forming thin films or substrates.

[0032] In one specific example, the polyimide 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 this invention, the term weight-average molecular weight refers to the value converted to standard polystyrene by GPC (gel permeation chromatography).

[0033] The first solvent according to the present invention is not particularly limited as long as it can dissolve polyamic acid. The first solvent may also be a polar solvent. 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 polarity of the first solvent is lower than that of the second solvent.

[0034] The first solvent mentioned above can be an aprotic polar solvent. The second solvent can be either an aprotic polar solvent or a protic polar solvent. For example, the second solvent may be an alcohol solvent such as methanol, ethanol, 1-propanol, butanol, isobutanol, 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; or a solvent such as dimethyl carbonate, methyl methacrylate, or propylene glycol monomethyl ether acetic acid.

[0035] This invention may include a first solvent and a second solvent. In this case, the content of the first solvent is greater than the content of the second solvent. Furthermore, the ratio of the second solvent to 100 parts by weight of the first solvent is 0.01 to 10 parts by weight. The lower limit of the above 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.

[0036] The polyamic acid composition according to the present invention further includes inorganic particles. These inorganic particles have an average particle size, for example, in the 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 less than 25 nm, and the upper limit may be, for example, 70 nm, 60 nm, 55 nm, 48 nm, or less than 40 nm. In this invention, the average particle size can be obtained based on D50 particle size analysis. By adjusting the above-mentioned particle size range, the present invention can improve compatibility with polyamic acid and achieve the target physical properties after curing.

[0037] There is no particular limitation on the type of inorganic particles mentioned above, but they may include silica, alumina, titanium dioxide, zirconium oxide, yttrium oxide, mica, clay, zeolite, chromium oxide, zinc oxide, iron oxide, magnesium oxide, calcium oxide, scandium oxide, or barium oxide. Furthermore, the surface of the inorganic particles of the present invention may contain a surface treatment agent. Such surface treatment agents may include, for example, silane coupling agents. The aforementioned silane coupling agents may be one or more selected from the group consisting of epoxy, amino, and thiol compounds. Specifically, the aforementioned epoxy compounds include (3-glycidoxypropyl)trimethoxysilane (GPTMS); the aforementioned amino compounds include (3-aminopropyl)trimethoxysilane (APTMS); and the aforementioned thiol compounds include (3-mercaptopropyl)trimethoxysilane (MPTMS), but are not limited thereto. Furthermore, the aforementioned surface treatment agent may include dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), or tetraethoxysilane (TEOS). In this invention, surface treatment can be performed on the inorganic particles using one surface treatment agent, or it can be performed using two different surface treatment agents. Additionally, the content of the aforementioned inorganic particles, relative to 100 parts by weight of polyamic acid, may include 1 to 20 parts by weight. The lower limit of the aforementioned 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 combining the aforementioned inorganic particles with the polyamic acid composition, this invention can improve dispersibility and mixability, and achieve adhesion and heat resistance durability after curing.

[0038] The polyamic acid composition described above has a coefficient of thermal expansion (CTE) of less than 40 ppm / ℃ after curing. In one specific example, the upper limit of the CTE is 40 ppm / ℃, 35 ppm / ℃, 30 ppm / ℃, 25 ppm / ℃, 20 ppm / ℃, 18 ppm / ℃, 15 ppm / ℃, 13 ppm / ℃, 10 ppm / ℃, 8 ppm / ℃, 7 ppm / ℃, 6 ppm / ℃, 5 ppm / ℃, 4.8 ppm / ℃, 4.3 ppm / ℃, 4 ppm / ℃, 3.7 ppm / m, 3.5 ppm, 3 ppm / m, 2.8 ppm / ℃, or 2.6 ppm / ℃ or less; the lower limit of the CTE is 0.1 ppm / ℃, 1 ppm / ℃, 2.0 ppm / ℃, 2.6 ppm / ℃, 2.8 ppm / ℃, 3.5 ppm / ℃, or 4 ppm / ℃ or more. In one specific example, the coefficient of thermal expansion is measured within the range of 100℃ to 450℃. The aforementioned CTE can be performed using a TA thermomechanical analyzer Q400 model. The polyimide film is cut into samples 2 mm wide and 10 mm long. Under a nitrogen atmosphere, a tension of 0.05 N is applied, and the temperature is increased from room temperature to 500 °C at a rate of 10 °C / min. Then, it is cooled again at a rate of 10 °C / min, while the tilt between 100 °C and 450 °C is measured.

[0039] Furthermore, the elongation of the above-mentioned polyamic acid composition after curing can reach 10% or more. In specific examples, it can 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 above elongation is determined by cutting the polyamic acid composition into a polyimide film, cutting it into samples 10 mm wide and 40 mm long, and then using an Instron 5564UTM instrument from Instron Corporation, according to the ASTM D-882 method.

[0040] Furthermore, the polyamic acid composition of the present invention, after curing, has an elastic modulus in the range of 6.0 GPa to 11 GPa. The lower limit of the above-mentioned elastic modulus can be 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 higher, and the upper limit can be 10.8 GPa, 10.5 GPa, 10.2 GPa, or 10.0 GPa or lower. In addition, the tensile strength of the polyamic acid composition after curing can be in the range of 300 MPa to 600 MPa. The lower limit of the aforementioned tensile strength can be, for example, 350 MPa, 400 MPa, 450 MPa, 480 MPa, 500 MPa, 530 MPa, or 540 MPa or higher, and the upper limit can be, for example, 580 MPa, 570 MPa, 560 MPa, 545 MPa, 530 MPa, or 500 MPa or lower. The aforementioned elastic modulus and tensile strength were determined using the ASTM D-882 method. A polyimide film was prepared by curing the aforementioned polyamic acid composition, then cut into specimens 10 mm wide and 40 mm long. The elastic modulus and tensile strength were then measured using an Instron 5564UTM instrument. The crossover time was measured at a rate of 50 mm / min.

[0041] According to the polyamic acid composition of the present invention, the glass transition temperature after curing can reach 300°C or higher. The upper limit of the aforementioned glass transition temperature can be 800°C or below 700°C, and the lower limit can 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 aforementioned glass transition temperatures are determined using TMA at a rate of 10°C / min for the polyimide prepared after curing the polyamic acid composition.

[0042] According to the polyamic acid composition of the present invention, the thermal decomposition temperature of 1% by weight after curing can reach 500°C or higher. The above-mentioned thermal decomposition temperature can be measured using a TA thermogravimetric analysis (TGA) Q50 model. In one specific example, the polyimide obtained by curing the above-mentioned polyamic acid is heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, and then held at this temperature for 30 minutes to remove moisture. Afterwards, the temperature is increased to 600°C at a rate of 10°C / min, and the temperature at which 1% weight loss occurs can be determined. The lower limit of the aforementioned thermal decomposition temperature can be, for example, 510℃, 515℃, 518℃, 523℃, 525℃, 528℃, 530℃, 535℃, 538℃, 545℃, 550℃, 560℃, 565℃, 568℃, 570℃, 580℃, 583℃, 585℃, 588℃, 590℃ or above, and the upper limit can be, for example, 800℃, 750℃, 700℃, 650℃ or below 630℃.

[0043] Furthermore, the polyamic acid composition according to the present invention, after curing, can achieve a transmittance of 50% to 80% in any wavelength band of the visible light region (380 to 780 nm). The lower limit of the aforementioned transmittance can be, for example, 55%, 58%, 60%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, or 71% or more, and the upper limit can be 78%, 75%, 73%, 72%, 71%, 69%, 68%, 67%, 66%, 65%, or 64% or less.

[0044] In addition, the present invention relates to a method for preparing a polyamic acid composition, specifically a method for preparing the aforementioned polyamic acid composition.

[0045] The above preparation method further includes a heating step at a temperature of at least 50°C. This heating step can be, for example, above 55°C, above 58°C, above 60°C, above 63°C, above 65°C, or above 68°C, with upper limits such as below 100°C, below 98°C, below 93°C, below 88°C, below 85°C, below 83°C, below 80°C, below 78°C, below 75°C, below 73°C, or below 71°C. The invention may also include a step of mixing the organic solvent and dianhydride monomer components before the above heating step. The invention can perform the above heating step after the mixing step, thus allowing heating to be carried out in a state containing the organic solvent and dianhydride monomer. By performing a heating step at a higher temperature than conventional processes, the invention can achieve the target structure of polyamic acid, increasing the length of the entire polymer chain after curing, and these polymers can achieve excellent heat resistance, dimensional stability, and mechanical properties.

[0046] In one specific example, the polyamic acid composition of the present invention can be prepared by the following polymerization method.

[0047] For example: (1) Polymerize by adding all the diamine monomers into the solvent and then adding dianhydride monomers to make them substantially equimolar with the diamine monomers;

[0048] (2) Polymerize by adding all the dianhydride monomers into the solvent and then adding the diamine monomers to make them substantially equimolar with the dianhydride monomers;

[0049] (3) After placing some of the components of the diamine monomer into the solvent, for the reaction components, mix some of the components of the dianhydride monomer in a ratio of about 95 to 105 mol%, add the remaining diamine monomer components, and continuously add the remaining dianhydride monomer on this basis, so that the diamine monomer and the dianhydride monomer are actually equimolarly polymerized.

[0050] (4) After placing some of the components of the dianhydride monomer into the solvent, for the reaction components, after mixing some of the components of the diamine monomer in a ratio of about 95 to 105 mol%, the remaining dianhydride monomer components are added, and on this basis, the remaining diamine monomer is continuously added, so that the diamine monomer and the dianhydride monomer are actually equimolarly polymerized.

[0051] (5) In a solvent, a portion of the diamine monomer component and a portion of the dianhydride monomer component are reacted to form a first composition, wherein one of the reactants is in excess. In another solvent, a portion of the diamine monomer component and a portion of the dianhydride monomer component are reacted to form a second composition, wherein one of the reactants is in excess. The polymerization is completed by using the first and second compositions as a mixed composition. Here, when the diamine monomer component is in excess when forming the first composition, the dianhydride monomer component is in excess in the second composition, or when the dianhydride monomer component is in excess in the first composition, the diamine monomer component is in excess in the second composition. Alternatively, the first and second compositions can be mixed to polymerize the total diamine monomer component and the dianhydride monomer component used in these reactions in substantially equimolar amounts.

[0052] The aggregation methods described above are not limited to the examples above; of course, any known method can be used.

[0053] The steps for preparing the above-mentioned polyamic acid composition can be carried out at 30 to 80°C.

[0054] Furthermore, the present invention relates to polyimides comprising the cured product of the above-described polyamic acid composition. Additionally, the present invention provides a polyimide film comprising the above-described polyimide. The above-described polyimide film can be a polyimide film for a substrate, and in a specific example, it can also be a polyimide film for a TFT substrate.

[0055] In addition, the present invention provides a method for preparing a polyimide film, the method comprising the steps of forming a film on a support by preparing a polyamic acid composition according to the above-described method for preparing a polyamic acid composition, drying to prepare a gel film, and then curing the gel film.

[0056] Specifically, in the method for preparing the polyimide film of the present invention,

[0057] A gel film is prepared by forming the above-mentioned polyimide precursor composition on a support. In the step of curing the gel film, the polyimide precursor composition formed on the support is dried at a temperature of 20 to 120°C for 5 to 60 minutes to prepare the gel film. The gel film is heated to 30 to 500°C at a rate of 1 to 8°C / min, heat-treated at 450 to 500°C for 5 to 60 minutes, and cooled to 20 to 120°C at a rate of 1 to 8°C / min.

[0058] The curing step of the gel film described above can be carried out at a temperature of 30 to 500°C. For example, the curing step of the gel film described above can 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.

[0059] The thickness of the polyimide film is 10 to 20 μm. For example, the thickness of the polyimide film can 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.

[0060] The aforementioned support can be, for example, an inorganic substrate. Examples of inorganic substrates include glass substrates and metal substrates, but glass substrates are preferred. The glass substrate can be made of soda lime glass, borosilicate glass, alkali-free glass, etc., but is not limited to these.

[0061] Technical effect

[0062] This invention relates to a polyamic acid composition having a high solids content and low viscosity, and the resulting polyimide and polyimide film after curing exhibit excellent heat resistance, dimensional stability, and mechanical properties. Detailed Implementation

[0063] The present invention is described in more detail below through embodiments and comparative examples, but the scope of the present invention is not limited to the embodiments presented below.

[0064] <Preparation of Polyamic Acid Solution>

[0065] Example 1

[0066] N-methylpyrrolidone (NMP) was introduced into a 500 ml reactor equipped with a stirrer and nitrogen injection / exhaust pipe, while nitrogen was simultaneously injected. Methanol (MeOH), a second solvent, was added as an additional solvent and stirred. After setting the reactor temperature to 70 °C, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) was added as a dianhydride monomer to initiate the reaction. The temperature was then lowered to 30 °C under a nitrogen atmosphere, and p-phenylenediamine (PPD) was completely dissolved in the reaction solution as a diamine monomer and rapidly stirred. The temperature was then raised to 40 °C and stirred for 120 minutes to prepare a polyimide solution.

[0067] Examples 2-6

[0068] Except for adjusting the monomers, content ratios, and solvent types in Example 1 as shown in Table 1, the polyamic acid solution was prepared using the same method as in Example 1.

[0069] Comparative Examples 1-4

[0070] Except for adjusting the monomers, content ratios, and solvent types in Example 1 as shown in Table 1, the polyamic acid solution was prepared using the same method as in Example 1.

[0071] Table 1

[0072]

[0073]

[0074] The solubility of the solvents described above is a measure of the degree to which BPDA and / or PMDA used in the examples and comparative examples dissolve in different solvents.

[0075] <Manufacturing of polyimides for measuring physical properties>

[0076] The polyamic acid compositions prepared in the above examples and comparative examples were degassed by high-speed rotation at 1,500 rpm or higher. Subsequently, the degassed polyamic acid compositions were coated onto a glass substrate using a spin coater. A gel film was then prepared by drying under a nitrogen atmosphere at 120°C for 30 min. The gel film was then heated to 450°C at a rate of 2°C / min, heat-treated at 450°C for 60 min, and cooled to 30°C at a rate of 2°C / min to obtain a polyimide film.

[0077] The polyimide film was then dipped in distilled water and peeled off from the glass substrate. The physical properties of the prepared polyimide film were measured using the following method, and the results are shown in Table 2 below.

[0078] Experimental Example 1 - Viscosity

[0079] For the polyimide precursor compositions prepared 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 of 1 mm.

[0080] Experimental Example 2 - CTE

[0081] Using a TA Instruments Q400 thermomechanical analyzer, a polyimide film was cut into pieces 2 mm wide and 10 mm long. Under a nitrogen atmosphere, a tension of 0.05 N was applied, and the temperature was increased from room temperature to 500 °C at a rate of 10 °C / min. When the temperature was cooled again at a rate of 10 °C / min, the cross-sectional gradient from 100 °C to Tg was measured.

[0082] Experimental Example 3 - Glass Transition Temperature

[0083] For the polyimide films prepared in the examples and comparative examples, the rapid expansion point was measured using TMA at 10°C / min as the set point.

[0084] Experimental Example 4-1: Thermal decomposition temperature (Td) % by weight

[0085] Using a TA Instruments Q50 thermogravimetric analyzer, the polyimide obtained by curing the aforementioned polyamic acid was heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, and then held at this temperature for 30 minutes to remove moisture. Afterwards, the temperature was increased to 600°C at a rate of 10°C / min to determine the temperature at which 1% weight loss occurred.

[0086] Experimental Example 5 - Light Transmittance: For the polyimide film prepared above, the light transmittance was measured in the wavelength range of 380 nm to 780 nm using a UV-Vis Spectrometer, and its average value was calculated.

[0087] Experimental Example 5 - Solubility after Polymerization

[0088] In the examples and comparative examples, the solubility of the manufactured polyimide compositions was observed. O was characterized by uniform dissolution without precipitation, while X was characterized by the formation of precipitate.

[0089] Table 2

[0090]

Claims

1. A polyamic acid composition, characterized in that... include, Polyamic acid containing dianhydride monomers and diamine monomers as polymerization units, and organic solvents. The solvent includes a first solvent and a second solvent, wherein the second solvent has a solubility of less than 1.5 g / 100 g relative to the dianhydride monomer. The first solvent is N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone. The ratio of the second solvent to 100 parts by weight of the first solvent is 0.01 to 10 parts by weight. Wherein, the second solvent is isopropanol, dimethyl carbonate, or 1,2-dimethyl ether, and The coefficient of thermal expansion (CTE) of the cured composition is in the range of 8.7 to 30 ppm / ℃.

2. The polyamic acid composition according to claim 1, characterized in that: It also includes a first solvent having a solubility of 1.5 g / 100 g or more relative to the dianhydride monomer.

3. The polyamic acid composition according to claim 1, characterized in that: The content of the second solvent is 0.01 to 10% by weight of the total amount of the polyamic acid composition.

4. The polyamic acid composition according to claim 1, characterized in that: Dihydride monomers are monomers that, in addition to those contained in the polymerization unit, also include monomers with unpolymerized open-ring structures.

5. The polyamic acid composition according to claim 4, characterized in that: Dihydride monomers with open-ring structures participate in amidation reactions.

6. The polyamic acid composition according to claim 1, characterized in that: Diamine monomers 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-diaminobenzoylaniline (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).

7. The polyamic acid composition according to claim 1, characterized in that: The dianhydride monomer is pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA), 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), oxydiphenylcarboxylic acid dianhydride (ODPA), 4,4'-(hexafluoroisopropene) phthalic anhydride (6-FDA), or p-phenylene-bis(phenyltriterpenoid) dianhydride (TAHQ).

8. The polyamic acid composition according to claim 1, characterized in that: The solid content is 9% to 35%.

9. The polyamic acid composition according to claim 1, characterized in that: At a temperature of 23℃ and 1s -1 The viscosity obtained at the shear rate was in the range of 500 to 50,000 cP.

10. The polyamic acid composition according to claim 1, characterized in that: The weight-average molecular weight ranges from 10,000 g / mol to 500,000 g / mol.

11. The polyamic acid composition according to claim 1, characterized in that: It also includes inorganic particles.

12. The polyamic acid composition according to claim 1, characterized in that: After curing, the glass transition temperature is above 300℃.

13. A method for preparing a polyamic acid composition, characterized in that... The polyamic acid composition of claim 1 is prepared by including the step of heating at a temperature of at least 50°C.

14. A polyimide, characterized in that, The composition comprising the polyamic acid composition of claim 1.

15. A polyimide film for a substrate, characterized in that... It includes the polyimide of claim 14.

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