Polyamic acid composition and polyimide produced thereby

Abstract

This invention provides polyimides having relatively high molecular weight and excellent mechanical properties, as well as polyamic acid compositions capable of producing them. It also provides polyamic acid compositions with improved electrospinning properties without chemical crosslinking. [Solution] A polyamic acid composition is provided, comprising a polyamic acid containing a dianhydride monomer and a diamine monomer as polymerization units, and an additive containing imidazole, wherein the additive is present in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the polyamic acid.

Description

Technical Field

[0001] The present invention relates to a polyamic acid composition and a polyimide produced therefrom. Specifically, it relates to a polyamic acid composition capable of producing a polyimide with excellent mechanical properties by including an additive containing imidazole.

Background Art

[0002] Generally, polyimide (PI) is based on an imide ring with a very excellent chemical stability together with a rigid aromatic main chain. Among organic materials, it is a polymer material having the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance, and can be manufactured in various forms such as films, fiberization, and membranes. Due to such characteristics, polyimide is widely used in a wide range of fields as a high - end material and an insulating coating agent in the fields of electric and electronic, semiconductor, display, automobile, aviation, and space materials.

[0003] 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 a display substrate that can be used instead of an insulating material for a circuit board or a glass substrate for a display.

[0004] Polyimide can be produced by dissolving a dianhydride having two acid anhydride groups in a molecule and a diamine having two amino groups in a molecule in a solvent to synthesize a polyimide precursor called polyamic acid (PAA), then coating and drying, and heat - treating at a temperature of about 350 °C for imidization.

[0005] On the other hand, conventional polyamic acid compositions have a problem that although they have spinnability during electrospinning, there are many structures such as beads on a string connected to the yarn, and their mechanical properties are inferior.

[0006] Therefore, there is a need to develop polyimides that have improved electrospinning properties, relatively high molecular weight, and excellent mechanical properties. [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to provide a polyimide having a relatively high molecular weight and excellent mechanical properties, and a polyamic acid composition that can be used to produce the same.

[0008] Furthermore, the present invention aims to provide a polyamic acid composition in which electrospinning properties are improved without chemical crosslinking.

[0009] Furthermore, the present invention aims to provide a polyamic acid composition that can be used to produce polyimides that can be used as separators, membranes, films, or coating materials for secondary batteries. [Means for solving the problem]

[0010] Because the present invention can be modified in various ways and has various embodiments, specific embodiments will be illustrated and described in detail. However, this should not be understood as limiting the present invention to specific embodiments, but rather as including all modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0011] The terms used in this application are used solely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “includes” or “having” specify the presence of features, figures, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or possibility of adding one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0012] Wherever a quantity, concentration, or other value or parameter is given in this specification by enumeration of ranges, preferred ranges, preferred upper limits, and preferred lower limits, it should be understood that this specifically discloses all ranges formed by any pair of limits or preferred values ​​of any upper range and any limits or preferred values ​​of any lower range, regardless of whether the ranges are disclosed separately.

[0013] Where a range of numerical values ​​is referred to herein, unless otherwise specified, that range is intended not to be limited to the specific values ​​referred to when defining the range, including its endpoints and the models within that range.

[0014] In this specification, “dianhydride” is intended to include its precursors or derivatives, but it may also be referred to as “dianhydric acid,” “dianhydride,” or “acidic dianhydride.” These may not be technically dianhydrides, but nevertheless react with diamines to form polyamic acids, which can also be converted to polyimides.

[0015] In this specification, “diamine” is intended to include its precursors or derivatives, which may not be technically diamines, but nevertheless react with dianhydride acids to form polyamic acids, which can also be converted to polyimides.

[0016] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application. The specific details for realizing the invention are described below.

[0017] This invention relates to polyamic acid compositions and polyimides produced thereby.

[0018] Specifically, the present invention provides a polyamic acid composition comprising a polyamic acid containing a dianhydride monomer and a diamine monomer as polymerization units, and an additive containing imidazole, wherein the additive is present in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the polyamic acid.

[0019] Here, the imidazole is the imidazole represented by structural formula 1 below.

[0020] [ka]

[0021] Here, the polyamic acid composition may contain 0.01 to 5 parts by weight of the additive, preferably 0.01 to 3 parts by weight, 0.01 to 2.5 parts by weight, 0.01 to 2 parts by weight, 0.01 to 1.5 parts by weight, 0.01 to 1 part by weight, 0.01 to 0.5 parts by weight, 0.01 to 0.15 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, and 0.1 ~2.5 parts by weight, 0.1~2 parts by weight, 0.1~1.5 parts by weight, 0.1~1 parts by weight, 0.1~0.5 parts by weight, 0.15~5 parts by weight, 0.15~3 parts by weight, 0.15~2 .5 parts by weight, 0.15~2 parts by weight, 0.15~1.5 parts by weight, 0.15~1 parts by weight, 0.1~0.5 parts by weight, 0.2~5 parts by weight, 0.2~3 parts by weight, 0.2~2.5 parts by weight, 0.2~2 parts by weight, 0.2~1.5 parts by weight, 0.2~1 parts by weight, 0.1~0.5 parts by weight, 0.3~5 parts by weight, 0.3~3 parts by weight, 0.3~2.5 parts by weight, 0 .3~2 parts by weight, 0.3~1.5 parts by weight, 0.3~1 parts by weight, 0.1~0.5 parts by weight, 0.4~5 parts by weight, 0.4~3 parts by weight, 0.4~2.5 parts by weight, 0.4~2 parts by weight It may contain 100 parts, 0.4 to 1.5 parts by weight, 0.4 to 1 part by weight, 0.4 to 0.5 parts by weight, 0.5 to 5 parts by weight, 0.5 to 3 parts by weight, 0.5 to 2.5 parts by weight, 0.5 to 2 parts by weight, 0.5 to 1.5 parts by weight, 0.5 to 1 part by weight, 1 to 5 parts by weight, 1 to 3 parts by weight, 1 to 2.5 parts by weight, 1 to 2 parts by weight, 1 to 1.5 parts by weight, or 3 to 5 parts by weight. More preferably, it may contain 0.1 to 3 parts by weight, 0.2 to 2.5 parts by weight, 0.3 to 2 parts by weight, 0.4 to 1.5 parts by weight, and even more preferably, 0.5 to 1 part by weight.

[0022] If the additive is present in amounts less than 0.01 parts by weight, the mechanical properties will deteriorate, which is undesirable. If it is present in amounts exceeding 5 parts by weight, the viscosity and molecular weight will decrease during storage at room temperature / frozen, making storage difficult and reducing the electrospinning properties, which is also undesirable.

[0023] In this invention, imidazole is included not as an imidation catalyst, but as an additive to improve the electrospinning properties of polyamic acid. Even in small amounts of 0.01 to 5 parts by weight per 100 parts by weight of polyamic acid, the additive significantly improves electrospinning stability, and the polyimide film produced thereby exhibits excellent mechanical properties.

[0024] The aforementioned dianhydride monomers are biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianehydride (BTDA), oxydiphthalic dianehydride (ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianehydride (DSDA), bis(3,4-dicarboxyphenyl) sulfide dianehydride, and 2,2-bis(3,4-dicarboxyphenyl)-1 ,1,1,3,3,3-Hexafluoropropanedianehydride, 2,3,3',4'-Benzophenonetetracarboxylic dianehydride, Bis(3,4-Dicarboxyphenyl)methanedianehydride, 2,2-Bis(3,4-Dicarboxyphenyl)propanedianehydride, p-Phenylenebis(Trimellitic Monoester Acid Anhydride), p-Biphenylenebis(Trimellitic Monoester Acid Anhydride), m-Terphenyl-3,4,3',4'-Tetracarb Xylic dianehydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, 1,3-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyldianehydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propanedianehydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid di It may contain one or more selected from the group consisting of anhydrides, 1,4,5,8-naphthalenetetracarboxylic dianahydrides, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianahydrides, preferably one or more selected from the group consisting of biphenyltetracarboxylic dianahydrides (BPDA) and pyromeretic dianahydrides (PMDA), more preferably biphenyltetracarboxylic dianahydrides (BPDA).

[0025] Specifically, the dianhydride monomer can contain 90 mol% or more of the biphenyltetracarboxylic dianhydride (BPDA) based on 100 mol% of the total dianhydride monomer. By containing 90 mol% or more of the biphenyltetracarboxylic dianhydride, a polyimide excellent in the targeted mechanical properties can be produced.

[0026] On the other hand, the dianhydride monomer contains biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianehydride (BTDA), oxydiphthalic dianehydride (ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianehydride (DSDA), and bis(3,4-dicarboxyphenyl)sulfone. Fidociane hydrides, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropanediane hydride, 2,3,3',4'-benzophenone tetracarboxylic dianediane, bis(3,4-dicarboxyphenyl)methanediane hydride, 2,2-bis(3,4-dicarboxyphenyl)propanediane hydride, p-phenylene bis(trimeltic monoester acid anhydride) ), p-biphenylenebis(trimeltic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, 1,3-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)benzenedianehydride The material may further contain one or more selected from the group consisting of boxyphenoxy)biphenyl dianehydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propanedianehydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianehydride, 1,4,5,8-naphthalenetetracarboxylic dianehydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianehydride. Preferably, it may further contain pyromeretic dianehydride (PMDA).

[0027] The diamine monomers include 4,4'-diaminodiphenyl ether (4,4'-ODA), 1,4-diaminobenzene (PPD), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-tolidine), 2,2-bisaminophenoxyphenylpropane (BAPP), metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid. (DABA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl Nyl sulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 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 Nyl)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, 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 (TPE-R), 1,4-bis(3-aminophenoxy)benzene (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-aminophenyl sulfide)benzene, 1,3-bis(4-aminophenyl sulfide)benzene, 1,4-bis(4-aminophenyl sulfide)benzene, 1,3 -Bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,One or more selected from the group consisting of 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[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 and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane can be included, and preferably, one or more selected from the group consisting of 1,4-diaminobenzene (PPD) and 4,4'-diaminodiphenyl ether (ODA) can be included.,

[0028] The diamine monomer may contain 50 mol% or more of 1,4-diaminobenzene (PPD) relative to 100 mol% of the total diamine monomer, specifically in the following proportions: 50-100 mol%, 55-90 mol%, 60-85 mol%, 65-80 mol%, and 68-75 mol%. When 1,4-diaminobenzene (PPD) is present at a ratio of 100 mol%, 4,4'-diaminodiphenyl ether (ODA) may be present at a ratio of 0 mol%.

[0029] The diamine monomer may contain 50 mol% or less of 4,4'-diaminodiphenyl ether (ODA) relative to 100 mol% of the total diamine monomer, specifically in the following proportions: 0-50 mol%, 10-45 mol%, 15-40 mol%, 20-35 mol%, and 25-32 mol%. When 4,4'-diaminodiphenyl ether (ODA) is present at a ratio of 0 mol%, 1,4-diaminobenzene (PPD) may be present at a ratio of 100 mol%.

[0030] In other words, the sum of the content of 1,4-diaminobenzene (PPD) and the content of 4,4'-diaminodiphenyl ether (ODA) may be 100 mol% with respect to 100 mol% of the total diamine monomer.

[0031] By including 50 mol% or more of 1,4-diaminobenzene (PPD) (and 50 mol% or less of 4,4'-diaminodiphenyl ether (ODA)) in the diamine monomer, a polyimide with the target mechanical properties can be produced.

[0032] In one embodiment, the polyamic acid may contain biphenyltetracarboxylic dianehydride (BPDA), 1,4-diaminobenzene (PPD), and 4,4'-diaminodiphenyl ether (ODA) as polymerization units.

[0033] In one embodiment, the polyamic acid may contain biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), 1,4-diaminobenzene (PPD), and 4,4'-diaminodiphenyl ether (ODA) as polymerization units.

[0034] The molar ratio of the dianhydride monomer to the diamine monomer may be 6:4 to 4:6, preferably 5.5:4.5 to 4.5:6.5, and more preferably 5:5.

[0035] The polyamic acid may contain 90 to 110 mol% of the diamine monomer, preferably 95 to 105 mol%, more preferably 98 to 102 mol%, and even more preferably 99 to 101 mol%.

[0036] The polyamic acid may contain 90 to 110 mol% of the dianhydride monomer, preferably 95 to 105 mol%, more preferably 98 to 102 mol%, and even more preferably 100 mol%.

[0037] The polyamic acid may contain 95 to 105 mol% of the dianhydride monomer per 100 mol% of the diamine monomer. For example, the lower limit may be 95.5 mol% or more, 96 mol% or more, 96.5 mol% or more, 97 mol% or more, 97.5 mol% or more, 98 mol% or more, 98.5 mol% or more, 99 mol% or more, or 99.5 mol% or more, and the upper limit may be 105 mol% or less, 104 mol% or less, 103 mol% or less, 102 mol% or less, 101 mol% or less, or 100 mol% or less.

[0038] The polyamic acid composition may further contain a solvent.

[0039] The solvent may include one or more selected from the group consisting of N,N'-dimethylacetamide (DMAc), N,N'-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), diethylacetamide (DEAc), N-ethyl-2-pyrrolidone (NEP), N,N'-diethylformamide (DEF)dimethylpropanamide (DMPA), and γ-butyrolactone (GBL), and preferably, N,N'-dimethylacetamide (DMAc) can be used.

[0040] The viscosity of the polyamic acid composition may be between 5,000 and 300,000 cP.

[0041] The weight-average molecular weight (Mw) of the polyamic acid composition is preferably 10,000 to 500,000 (g / mol), more preferably 100,000 to 400,000 (g / mol), 150,000 to 350,000 (g / mol), 180,000 to 320,000 (g / mol), and even more preferably 200,000 to 300,000. A molecular weight of 10,000 to 500,000 is preferable because it allows for smooth electrospinning and improves process stability. It has been confirmed that the polyamic acid composition of the present invention has a higher molecular weight than conventional polyamic acid compositions that do not contain imidazole.

[0042] In one embodiment, the polyamic acid composition may have a cured modulus of 4 GPa or higher. For example, the lower limit of the modulus may be 4.5 GPa or higher, 4.7 GPa or higher, or 5 GPa or higher. The upper limit of the modulus is not particularly limited, but may be 18 GPa or lower, 17 GPa or lower, 16 GPa or lower, or 15 GPa or lower. The modulus was measured using an Instron 5564 UTM instrument manufactured by INSTRON, with samples measuring 220 mm in length and 15 mm in width at a speed of 10 mm / min, and the average of 10 samples was calculated.

[0043] In one embodiment, the polyamic acid composition may have a cured tensile strength of 180 MPa or higher. For example, the lower limit of the tensile strength may be 190 MPa or higher, 195 MPa or higher, 200 MPa or higher, 205 MPa or higher, 210 MPa or higher, 215 MPa or higher, or 220 MPa or higher. The upper limit of the tensile strength is not particularly limited, but may be 400 MPa or lower. The tensile strength was measured using an Instron 5564 UTM instrument manufactured by INSTRON, Inc., with samples measuring 220 mm in length and 15 mm in width, at a grip spacing of 50 mm and a speed of 10 mm / min, in accordance with the ASTM D-882 standard, and the average of 10 samples was calculated.

[0044] In one embodiment, the polyamic acid composition may have an elongation of 9% or more after curing. For example, the lower limit of the elongation may be 10% or more, 11% or more, 12% or more, 12.5% ​​or more, 12.8% or more, or 13% or more. The upper limit of the elongation is not particularly limited, but may be 80% or less. In one embodiment, the elongation can be measured using an Instron 5564 UTM instrument manufactured by INSTRON, Inc., by preparing a sample with a length of 220 mm and a width of 15 mm, and measuring the elongation at a speed (10 mm / min) in accordance with the ASTM D-882 standard.

[0045] Another embodiment of the present invention provides a polyimide comprising a cured product of the polyamic acid composition.

[0046] Yet another embodiment of the present invention provides a polyimide film produced using the polyamic acid composition.

[0047] The thickness of the polyimide film can be appropriately selected considering the application, usage environment, and physical properties of the polyimide film. For example, the thickness of the polyimide film may be 1 to 100 μm, 15 to 70 μm, 25 to 50 μm, or 30 to 45 μm, but is not limited to these. [Effects of the Invention]

[0048] The polyamic acid composition according to the present invention can provide a polyimide having a relatively high molecular weight and excellent mechanical properties.

[0049] Furthermore, the polyamic acid composition according to the present invention can have its electrospinning properties (processability) improved by using an additive containing imidazole without chemical crosslinking.

[0050] Furthermore, the polyamic acid composition according to the present invention and the polyimide produced thereby have the effect of being applicable to separators, membranes, films, or coating materials for secondary batteries. [Brief explanation of the drawing]

[0051] [Figure 1] This is an SEM image of the polyamic acid composition produced by Example 1-1 after electrospinning. [Figure 2] These are SEM images of the polyamic acid compositions produced by Example 1-2 after electrospinning. [Figure 3] This is an SEM image of the polyamic acid composition produced by Comparative Example 1-1 after electrospinning. [Figure 4] These are images of the polyamic acid compositions prepared by Examples 1-2, 1-5, and Comparative Examples 1-6 after being stored frozen (-15°C). [Modes for carrying out the invention]

[0052] To aid in understanding the present invention, examples are provided below. The following examples are provided to facilitate understanding of the present invention and do not limit the scope of the invention.

[0053] <Example 1. Polyamic acid composition> Example 1-1 Under a nitrogen atmosphere at 35°C, 70 mol% of 1,4-diaminobenzene (PPD) was dissolved in an organic solvent, N,N'-dimethylacetamide (DMAc). Next, 100 mol% of biphenyltetracarboxylic dianehydride (BPDA) was added and the mixture was stirred for 3 hours. Then, 30 mol% of 4,4'-diaminodiphenyl ether (ODA) was added to obtain polyamic acid. To the obtained polyamic acid, 1,500 ppm of imidazole (corresponding to 0.15 parts by weight per 100 parts by weight of the obtained polyamic acid) was mixed as an additive, and the mixture was stirred for 1 hour to produce a polyamic acid composition.

[0054] Examples 1-2 to 1-9, Comparative Examples 1-1 to 1-6 A polyamic acid composition was prepared using the same method as in Example 1-1, except that the types and contents of the dianhydride monomer and diamine monomer used, and the types and contents of the additives used were changed as shown in Table 1.

[0055] Table 1 below lists the types and contents of monomers / additives used in the production of polyamic acid compositions according to Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-6.

[0056] [Table 1]

[0057] The abbreviations in Table 1 above are as follows: BPDA: Biphenyltetracarboxylic dianehydride PMDA: Pyromeretic dianhydride PPD: Paraphenylenediamine ODA: 4,4'-diaminodiphenyl ether

[0058] <Example 2: Polyimide film> Example 2-1 The polyamic acid composition produced in Example 1-1 was coated onto a glass substrate to a thickness of 20 μm using spin-coating, and a polyimide film was obtained by gradually increasing the temperature to 90°C, 170°C, 200°C, and 400°C.

[0059] Examples 2-2 to 2-9 and Comparative Examples 2-1 to 2-6 Polyimide films were produced in the same manner as in Example 2-1, except that the polyamic acid compositions were changed to those in Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-6, respectively.

[0060] <Example of experiment> Experimental Example 1. Confirmation of the molecular weight of polyamic acid compositions. To confirm the change in molecular weight due to the imidazole content, the weight-average molecular weight (Mw) of the polyamic acid compositions prepared by Examples 1-1 to 1-5 and Comparative Examples 1-1 and 1-6 is shown in Table 2 below.

[0061] Specifically, gel permeation chromatography (GPC) analysis was performed to confirm the weight-average molecular weight (Mw) of the polyamic acid compositions prepared by Examples 1-1 to 1-5 and Comparative Examples 1-1 and 1-6. The analysis was performed using an Agilent 1260 Infinity II GPC / SEC system with an Agilent PLgel Mixed-C column (300 × 7.5 mm, 5 μm). N-methyl-2-pyrrolidone (NMP) was used as the mobile phase, with a flow rate of 1.0 mL / min and a column temperature of 50°C. A differential refractive index detector was used, and the sample was dissolved in NMP at a concentration of 2 mg / mL, filtered through a 0.20 μm PTFE filter, and injected. Molecular weight correction was performed using monodisperse polystyrene standard samples.

[0062] [Table 2]

[0063] Table 2 shows that, with the same polyamic acid composition (BPDA 100 mol%, PPD 70 mol%, ODA 30 mol%), the molecular weight of the polyamic acid composition increases as the imidazole content increases.

[0064] Experimental Example 2. Evaluation of Mechanical Properties To compare the mechanical properties (modulus, tensile strength, elongation) with the addition of imidazole, the properties of polyimide films (Examples 2-1 and 2-2, Comparative Examples 2-1, 2-4, and 2-5) produced from polyamic acid compositions (Examples 1-1 and 1-2, Comparative Examples 1-1, 1-4, and 1-5) having the same content of dianhydride monomers and diamine monomers were confirmed by the following method.

[0065] (1) Modulus The polyimide films of Examples 2-1 and 2-2, and Comparative Examples 2-1, 2-4, and 2-5 were prepared as samples measuring 220 mm in length and 15 mm in width using an Instron 5564 UTM instrument manufactured by INSTRON, Inc., measured at a speed of 10 mm / min, and the average of 10 samples was calculated and is shown in Table 3 below.

[0066] (2) Tensile strength The polyimide films of Examples 2-1 and 2-2, and Comparative Examples 2-1, 2-4, and 2-5 were prepared as samples measuring 220 mm in length and 15 mm in width using an Instron 5564 UTM instrument manufactured by INSTRON. Measurements were taken according to ASTM D-882 standards at a grip spacing of 50 mm and a speed of 10 mm / min, and the average of 10 samples was calculated and is shown in Table 3 below.

[0067] (3) Elongation The polyimide films of Examples 2-1 and 2-2, and Comparative Examples 2-1, 2-4, and 2-5 were prepared as samples measuring 220 mm in length and 15 mm in width using an Instron 5564 UTM instrument manufactured by INSTRON, Inc. The elongation was measured at a speed of 10 mm / min in accordance with the ASTM D-882 standard and is shown in Table 3 below.

[0068] [Table 3]

[0069] According to Table 3, polyimide films produced from a polyamic acid composition containing 100 mol% BPDA, 70 mol% PPD, and 30 mol% ODA can be confirmed to have a modulus of 6 GPa or higher, a tensile strength of 230 MPa or higher, and an elongation of 17% or higher when imidazole is used as an additive (Examples 2-1, 2-2). On the other hand, it can be confirmed that the films without additives (Comparative Example 2-1), or when 2-phenylimidazole and 1,2-dimethylimidazole are used as additives (Comparative Examples 2-4, 2-5), have lower mechanical properties compared to when imidazole is used as an additive (Examples 2-1, 2-2).

[0070] Experimental Example 2. Evaluation of Processability (1) Confirmation of electrospinning properties After electrospinning the polyamic acid compositions prepared in Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-6, the electrospinning properties (processability) were evaluated based on images acquired with a SEM device, and are shown in Table 4 below.

[0071] Figure 1 is an SEM image of the polyamic acid composition produced by Example 1-1 after electrospinning, Figure 2 is an SEM image of the polyamic acid composition produced by Example 1-2 after electrospinning, and Figure 3 is an SEM image of the polyamic acid composition produced by Comparative Example 1-1 after electrospinning.

[0072] As shown in Figure 1, the polyamic acid composition produced by Example 1-1 contained a small amount of imidazole (1,500 ppm), and it was confirmed that while the electrospinning properties were slightly improved, it was difficult to form a web. Therefore, as shown in the shape of Figure 1, when the electrospinning properties were improved but web formation was difficult, it is indicated with a circle (○) in Table 4 below.

[0073] On the other hand, the polyamic acid composition produced by Example 1-2 contained 5,000 ppm of imidazole, and its improved electrospinning properties were confirmed in Figure 2. Therefore, when the electrospinning properties were improved and web formation was possible, as shown in the shape in Figure 2, it was indicated with ◎ in Table 4 below.

[0074] On the other hand, Comparative Example 1-1, which had the same dianhydride monomer and diamine monomer composition but did not contain imidazole, was found to have many bead-on-string structures, as can be seen from Figure 3. Therefore, when electrospinning properties were not improved and many bead-on-string structures were formed, as shown in the shape in Figure 3, it was indicated by a triangle (△) in Table 4 below. When there are many bead-on-string structures, the mechanical properties are inferior and therefore undesirable.

[0075] [Table 4]

[0076] In the electrospinning properties shown in Table 4 above, each symbol has the following meaning: ◎: Improved electrospinning properties enable web formation. ○: Electrospinning properties improved, but web formation was difficult. △: Electrospinning properties did not improve, and many bead-on-string structures were formed. ×: Electrospinning impossible

[0077] According to Table 4, the electrospinning properties of the polyamic acid composition of the present invention are improved by the inclusion of imidazole. In particular, when 0.5 parts by weight (5,000 ppm) or 1 part by weight (10,000 ppm) of imidazole is included per 100 parts by weight of polyamic acid, it can be confirmed that the electrospinning properties are improved to the extent that web formation is possible.

[0078] (2) Confirmation of freezing and storage suitability Figure 4 shows images of Examples 1-2, 1-5, and Comparative Examples 1-6 after being stored frozen (-15°C).

[0079] As shown in Figure 4, Examples 1-2, which contained 5,000 ppm of imidazole, showed no change over time even after being stored frozen for 7 days. Examples 1-5, which contained 50,000 ppm of imidazole, did not develop haze within 2 days of frozen storage, but haze was observed to develop after 2 days or more.

[0080] On the other hand, Comparative Examples 1-6, which contained 51,000 ppm of imidazole, were confirmed to have formed a gel after 6 hours.

[0081] From this, it was confirmed that when the imidazole content is 50,000 ppm or less, stable transparency is maintained for more than two days, but when it exceeds this amount, haze and gel formation occurs in just 6 hours, and the ability to be stored frozen deteriorates rapidly. Therefore, it was confirmed that even a slight difference in content of about 1,000 ppm results in a clear difference in stability.

[0082] In other words, the present invention contains an appropriate amount of an additive containing imidazole, and does not undergo any changes over time even after frozen storage, and has the effect of maintaining excellent electrospinning properties (processability).

[0083] This specification omits detailed descriptions of matters that can be easily understood and inferred by a person with ordinary skill in the art of the present invention. Beyond the specific examples provided herein, various modifications are possible without altering the technical concept or essential configuration of the present invention. Therefore, the present invention can be implemented in ways different from those specifically described and illustrated herein, and this is understandable to a person with ordinary skill in the art of the present invention.

Claims

1. A polyamic acid containing dianhydride monomers and diamine monomers as polymerization units, It contains an additive containing imidazole, The additive is contained in a polyamic acid composition in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the polyamic acid.

2. The polyamic acid composition according to claim 1, wherein the polyamic acid composition contains 0.1 to 3 parts by weight of the additive per 100 parts by weight of the polyamic acid.

3. The polyamic acid composition according to claim 2, wherein the polyamic acid composition contains 0.5 to 1 part by weight of the additive per 100 parts by weight of the polyamic acid.

4. The aforementioned dianhydride monomers include biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianehydride (BTDA), oxydiphthalic dianehydride (ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianehydride (DSDA), and bis(3,4-dicarboxyphenyl) sulfide dianehydride. Hydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropanedianehydride, 2,3,3',4'-benzophenonetetracarboxylic dianehydride, bis(3,4-dicarboxyphenyl)methanedianehydride, 2,2-bis(3,4-dicarboxyphenyl)propanedianehydride, p-phenylenebis(trimeltic monoester acid anhydride), p-biphenyl Lenbis (trimeltic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, 1,3-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy) The polyamic acid composition according to claim 1, comprising one or more selected from the group consisting of biphenyl dianehydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propanedianehydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianehydride, 1,4,5,8-naphthalenetetracarboxylic dianehydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianehydride.

5. The polyamic acid composition according to claim 1, wherein the dianhydride monomer contains 90 mol% or more of the biphenyltetracarboxylic dianehydride (BPDA) based on 100 mol% of the total dianhydride monomer.

6. The diamine monomers are 4,4'-diaminodiphenyl ether (4,4'-ODA), 1,4-diaminobenzene (PPD), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-tolidine), 2,2-bisaminophenoxyphenylpropane (BAPP), metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, and 3,5-diaminobenzoic acid. (DABA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl Nyl 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 Nyl)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, 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 (TPE-R), 1,4-bis(3-aminophenoxy)benzene (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-aminophenyl sulfide)benzene, 1,3-bis(4-aminophenyl sulfide)benzene, 1,4-bis(4-aminophenyl sulfide)benzene, 1,3 -Bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 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 [3-(3-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 [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[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophenoxy A polyamic acid composition according to claim 1, comprising one or more selected from the group consisting of )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, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

7. The polyamic acid composition according to claim 1, wherein the diamine monomer contains 50 mol% or more of 1,4-diaminobenzene (PPD) with respect to 100 mol% of the total diamine monomer.

8. The polyamic acid composition according to claim 1, wherein the diamine monomer contains 50 mol% or less of the 4,4'-diaminodiphenyl ether (ODA) based on 100 mol% of the total diamine monomer.

9. The polyamic acid composition according to claim 1, wherein the modulus of the polyamic acid composition after curing is 4 GPa or more.

10. The polyamic acid composition according to claim 1, wherein the tensile strength of the polyamic acid composition after curing is 180 MPa or more.

11. The polyamic acid composition according to claim 1, wherein the elongation of the polyamic acid composition after curing is 9% or more.

12. A polyimide comprising a cured product of a polyamic acid composition according to any one of claims 1 to 11.

13. A polyimide film produced using the polyamic acid composition described in any one of claims 1 to 11.

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