Polyimide precursor including an environmentally friendly solvent and a polyimide film having excellent substrate adhesion and excellent heat resistance prepared therefrom

Abstract

This invention provides a polyimide precursor comprising: polyamic acid, the polyamic acid comprising a dianhydride monomer and a diamine monomer as polymerization units; and an environmentally friendly solvent, wherein the diamine monomer comprises a first diamine monomer and a second diamine monomer, the first diamine monomer and the second diamine monomer being different from each other, the second diamine monomer comprising 3,4'-diaminodiphenyl ether (3,4'-ODA), and based on 100 mol% of the total diamine monomers, the diamine monomer comprises a first diamine monomer in an amount of 80 mol% to 99.9 mol% and a second diamine monomer in an amount of 0.01 mol% to 20 mol%.

Description

Technical Field

[0001] This disclosure relates to polyimide precursors comprising environmentally friendly solvents and polyimide films prepared therefrom, which exhibit excellent substrate adhesion and excellent heat resistance. More specifically, the present invention relates to a polyimide precursor comprising 3,4'-diaminodiphenyl ether (3,4'-ODA) and a polyimide film prepared therefrom, which exhibits excellent substrate adhesion and excellent heat resistance. Background Technology

[0002] Polyimide is a polymer material based on its rigid aromatic backbone and extremely stable imide ring structure, exhibiting exceptionally high heat resistance, chemical resistance, electrical resistance, and weather resistance among organic materials. Polyimide can be prepared in various forms, including films, fibers, and membranes. These properties make polyimide a widely used advanced material in high-end electronics, semiconductors, displays, automotive, aerospace, and space applications, and it is also used as an insulating coating.

[0003] Especially for display applications, polyimide must be transparent. To reduce the risk of defects in the substrate due to residual stress during the heat treatment process in display manufacturing, polyimide must have a non-negative coefficient of thermal expansion at temperatures above 350°C. Furthermore, for display applications, polyimide must exhibit excellent adhesion to silicon wafers, glass, or metals.

[0004] Meanwhile, polyimides can be prepared by dissolving an acid dianhydride with two anhydride groups per molecule and a diamine with two amino groups per molecule in a solvent to synthesize a polyimide precursor called polyamic acid (PAA). This precursor is then coated, dried, and heat-treated at approximately 350°C to imidize it. In this case, the polyimide is prepared in solvents currently classified as hazardous, such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). NMP is a particularly good solvent for some polyimide or polyamic acid-based polymers, capable of dissolving polymers that are insoluble in other solvents. However, NMP is a reproductive toxin, or reproductive poison. In the electronics industry, many polymer applications require spin coating, slot die coating, or other deposition techniques that require the polymer to remain in solution until the solvent is removed for film casting. The viscosity of such polymer compositions must be compatible with these deposition techniques. This requirement limits the range of solvents available for polyimides. In the manufacture of electronic devices, suitable solvents are needed to replace NMP when used with polyimide.

[0005] Therefore, there is an urgent need to develop a polyimide that retains the basic properties of polyimide while exhibiting high substrate adhesion and excellent heat resistance, and that can be prepared using a suitable solvent instead of NMP. Summary of the Invention

[0006] [Technical Issues] The inventors have demonstrated that polyimide precursors comprising 3,4'-ODA (3,4'-diaminodiphenyl ether) and polyimide films prepared therefrom possess excellent appearance (no bubbles), high substrate adhesion, and excellent heat resistance, thereby completing this disclosure.

[0007] [Technical Solution] The purpose of this disclosure is to provide a polyimide precursor and a polyimide film prepared therefrom, the polyimide precursor using environmentally friendly solvents and exhibiting excellent appearance (no bubbles), high substrate adhesion and excellent heat resistance.

[0008] Another object of this disclosure is to provide a transparent polyimide precursor for a display and a polyimide film prepared therefrom.

[0009] [Beneficial Effects] The polyimide precursor and polyimide film prepared therefrom according to this disclosure utilize environmentally friendly solvents and exhibit excellent appearance (no bubbles), high substrate adhesion and excellent heat resistance.

[0010] Specifically, the polyimide precursor and the polyimide film prepared therefrom according to this disclosure include 3,4'-ODA, and the polymer chains formed by 3,4'-ODA have a more linear structure than those of 4,4'-ODA, which increases the packing density of the polymer chains, thereby resulting in higher substrate adhesion and excellent heat resistance.

[0011] Furthermore, the polyimide precursor and the polyimide film prepared therefrom according to this disclosure can be applied to displays. Detailed Implementation

[0012] [Best Mode] This disclosure is readily adaptable and can be implemented in various ways. Therefore, specific implementations have been detailed and described. However, this is not intended to limit this disclosure to any particular implementation, but rather to encompass all modifications, equivalents, and substitutions that fall within the spirit and technical scope of this disclosure.

[0013] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure. Singular forms include plural forms unless the context clearly indicates otherwise. In this disclosure, terms such as “comprising” or “having” are intended to specify the presence of the features, figures, steps, operations, components or combinations thereof described herein, and should not be construed as excluding the possibility of the presence or addition of one or more other features, figures, steps, operations, components or combinations thereof.

[0014] When the quantities, concentrations, or other values ​​or parameters given herein are listed as ranges, preferred ranges, or preferred upper and lower limits, it should be understood that this specifically discloses any range formed by any pair of any upper or preferred range values ​​and any lower or preferred range values, regardless of whether the range is disclosed individually.

[0015] When a numerical range is mentioned herein, it is intended to indicate that the endpoints of the range and the scope of the invention within that range are not limited to the specific values ​​mentioned when defining the range.

[0016] The term “dianhydride” as used herein is intended to include its precursors or derivatives, also referred to as “dianhydride acid,” “dianhydride,” or “acid dianhydride.” While not technically dianhydrides, they can still react with diamines to form polyamic acids, which can then be converted into polyimides.

[0017] The term “diamine” as used herein is intended to include its precursors or derivatives. Although they are diamines in a technical sense, they can still react with dianhydrides to form polyamic acids, which can then be converted into polyimides.

[0018] Unless otherwise defined, all terms (including technical and scientific terms used herein) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless expressly defined in this disclosure, terms such as those defined in common dictionaries shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and shall not be interpreted in an idealized or overly formal sense. Specific details of implementing the invention are described below.

[0019] This disclosure relates to polyimide precursors including environmentally friendly solvents and polyimide films prepared therefrom that exhibit excellent substrate adhesion and excellent heat resistance.

[0020] polyimide precursor This disclosure provides a polyimide precursor comprising: polyamic acid and an environmentally friendly solvent. The polyamic acid includes a dianhydride monomer and a diamine monomer as polymerization units. The diamine monomer includes a first diamine monomer and a second diamine monomer, which are distinct from each other. The second diamine monomer includes 3,4'-diaminodiphenyl ether (3,4'-ODA), and based on 100 mol% of the total diamine monomers, the diamine monomers comprise 80 mol% to 99.9 mol% of the first diamine monomer and 0.01 mol% to 20 mol% of the second diamine monomer.

[0021] Specifically, based on 100 mol% of total diamine monomers, the diamine monomers may include a first diamine monomer in an amount of 80 mol% to 99.9 mol%. For example, the lower limit may be 83 mol% or more, 85 mol% or more, 87 mol% or more, 90 mol% or more, 91 mol% or more, 92 mol% or more, 93 mol% or more, 94 mol% or more, or 95 mol% or more; the upper limit may be 99.7 mol% or less, 99.5 mol% or less, 99 mol% or less, 98.7 mol% or less, 98.5 mol% or less, 98.3 mol% or less, 98 mol% or less, 97.7 mol% or less, 97.5 mol% or less, 97.3 mol% or less, 97.2 mol% or less, 97.1 mol% or less, or 97 mol% or less.

[0022] Based on 100 mol% of total diamine monomers, the diamine monomers may include a second diamine monomer in an amount ranging from 0.01 mol% to 20 mol%. For example, the lower limit may be 0.03 mol% or more, 0.05 mol% or more, 1 mol% or more, 1.3 mol% or more, 1.5 mol% or more, 1.7 mol% or more, 2 mol% or more, 2.3 mol% or more, 2.5 mol% or more, 2.7 mol% or more, 2.8 mol% or more, 2.9 mol% or more, or 3 mol% or more; the upper limit may be 17 mol% or less, 15 mol% or less, 13 mol% or less, 10 mol% or less, 9 mol% or less, 8 mol% or less, 7 mol% or less, 6 mol% or less, or 5 mol% or less.

[0023] When the total diamine monomer content is 100 mol%, and the first diamine monomer content is less than 80 mol% (the second diamine monomer content is greater than 20 mol%), the prepared polyimide film exhibits low substrate adhesion and poor heat resistance, which is undesirable. When the first diamine monomer content is greater than 99.9 mol% (the second diamine monomer content is less than 0.01 mol%), the prepared polyimide film also exhibits poor substrate adhesion and heat resistance, which is also undesirable.

[0024] Environmentally friendly solvents may include at least one selected from the group consisting of dimethylpropionamide (DMPA), 3-methoxy-N,N-dimethylpropionamide, tetramethylurea (TMU), N-ethyl-2-pyrrolidone (NEP), and diethylformamide (DEF), and may preferably include DMPA. DMPA is an environmentally friendly organic solvent that can be treated after polymerization without a separate purification process, thereby reducing costs.

[0025] Dianone monomers may include at least one selected from the group consisting of: biphenyl dianhydride (BPDA), pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), diphenyl ether dianhydride (ODPA), diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride (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, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis( Triphenyltrioxide monoester anhydride), p-phenylenebis(triphenyltrioxide monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, and may preferably include BPDA.

[0026] The first diamine monomer may include at least one selected from the group consisting of: 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (4,4'-ODA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (meta-toluidine), 2,2-bis(aminophenoxyphenyl)propane (BAPP), m-phenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobenzidine, and m-phenylenediamine. 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzoylaniline, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-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'-dimethoxy Benzophenone, 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, 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'-bis(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-aminophenyl sulfone)benzene, 1,3-bis(4-aminophenyl sulfone)benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-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[3-(3-aminophenoxy)phenyl]methyl ketone, bis[3-(4-aminophenoxy)phenyl]methyl Ketones, bis[4-(3-aminophenoxy)phenyl] ketones, bis[4-(4-aminophenoxy)phenyl] ketones, bis[3-(3-aminophenoxy)phenyl] sulfides, bis[3-(4-aminophenoxy)phenyl] sulfides, bis[4-(3-aminophenoxy)phenyl] sulfides, bis[4-(4-aminophenoxy)phenyl] sulfides, bis[3-(3-aminophenoxy)phenyl] sulfones, bis[3-(4-aminophenoxy)phenyl] sulfones, bis[4-(3-aminophenoxy)phenyl] sulfones [3-(3-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-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[3 ... [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 may more preferably include PPD. When the first diamine monomer includes PPD, the polyimide film prepared from the polyimide composition exhibits excellent heat resistance.

[0027] More preferably, when the dianhydride monomer can be BPDA, the first diamine monomer can be PPD, and the second diamine monomer can be 3,4'-ODA. When the dianhydride monomer is BPDA, the first diamine monomer is PPD, and the second diamine monomer is 3,4'-ODA, the polyimide film prepared from the polyimide composition has excellent heat resistance.

[0028] The molar ratio of the dianhydride monomer to the diamine monomer can be from 1:2 to 2:1, preferably 1:1.

[0029] Based on 100 mol% of the diamine monomer, polyamic acid may include dianhydride monomers in amounts ranging from 95 mol% to 105 mol%. 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; 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.

[0030] Another embodiment of this disclosure provides a method for preparing a polyimide precursor.

[0031] Method for preparing polyimide precursors This disclosure provides a method for preparing a polyimide precursor, the method comprising: preparing polyamic acid by polymerizing a dianhydride monomer and a diamine monomer in an environmentally friendly solvent, thereby preparing a polyimide precursor comprising polyamic acid and an environmentally friendly solvent. The diamine monomer comprises a first diamine monomer and a second diamine monomer, the first and second diamine monomers being different from each other; and the second diamine monomer comprises 3,4'-diaminodiphenyl ether (3,4'-ODA). Based on 100 mol% of the total diamine monomers, the diamine monomers comprise a first diamine monomer in an amount of 80 mol% to 99.9 mol% and a second diamine monomer in an amount of 0.01 mol% to 20 mol%.

[0032] Specifically, based on 100 mol% of total diamine monomers, the diamine monomers may include a first diamine monomer in an amount of 80 mol% to 99.9 mol%. For example, the lower limit may be 83 mol% or more, 85 mol% or more, 87 mol% or more, 90 mol% or more, 91 mol% or more, 92 mol% or more, 93 mol% or more, 94 mol% or more, or 95 mol% or more; the upper limit may be 99.7 mol% or less, 99.5 mol% or less, 99 mol% or less, 98.7 mol% or less, 98.5 mol% or less, 98.3 mol% or less, 98 mol% or less, 97.7 mol% or less, 97.5 mol% or less, 97.3 mol% or less, 97.2 mol% or less, 97.1 mol% or less, or 97 mol% or less.

[0033] Based on 100 mol% of total diamine monomers, the diamine monomers may include a second diamine monomer in an amount ranging from 0.01 mol% to 20 mol%. For example, the lower limit may be 0.03 mol% or more, 0.05 mol% or more, 1 mol% or more, 1.3 mol% or more, 1.5 mol% or more, 1.7 mol% or more, 2% mol% or more, 2.3 mol% or more, 2.5 mol% or more, 2.7 mol% or more, 2.8 mol% or more, 2.9 mol% or more, or 3 mol% or more; the upper limit may be 17 mol% or less, 15 mol% or less, 13 mol% or less, 10 mol% or less, 9 mol% or less, 8 mol% or less, 7 mol% or less, 6 mol% or less, or 5 mol% or less.

[0034] When the total diamine monomer content is 100 mol%, and the first diamine monomer content is less than 80 mol% (the second diamine monomer content is greater than 20 mol%), the prepared polyimide film exhibits low substrate adhesion and poor heat resistance, which is undesirable. When the first diamine monomer content is greater than 99.9 mol% (the second diamine monomer content is less than 0.01 mol%), the prepared polyimide film also exhibits poor substrate adhesion and heat resistance, which is also undesirable.

[0035] The steps for preparing a polyimide precursor may include: (a) preparing a solution by mixing a dianhydride monomer into an environmentally friendly solvent; and (b) adding a first diamine monomer to the solution and subsequently adding a second diamine monomer, mixing the resulting mixture, and reacting the resulting mixture to prepare a solution comprising polyamic acid.

[0036] The reaction in step (b) can be carried out at room temperature (20°C to 25°C) for 4 to 24 hours, preferably 8 to 20 hours, more preferably 12 to 18 hours, and even more preferably 15 to 17 hours. By carrying out the reaction for 4 to 24 hours, polyamic acid and / or polyimide having the target repeating unit can be formed, and considering the degree to which the yield of polyamic acid increases over time, a solution comprising polyamic acid can be efficiently prepared.

[0037] Another embodiment of this disclosure provides a polyimide precursor prepared by a method for preparing a polyimide precursor.

[0038] polyimide film This disclosure provides a polyimide film comprising a cured product of a polyimide precursor.

[0039] The thickness of the polyimide film can be appropriately selected by considering factors such as its intended use, operating environment, and physical properties. For example, the thickness of the polyimide film can be 1μm to 100μm, 5μm to 50μm, 7μm to 30μm, 8μm to 20μm, or 9μm to 15μm, but is not limited to these.

[0040] The adhesion of the polyimide film to the amorphous silicon substrate can range from 1.0 N / cm to 2.5 N / cm. For example, the lower limit of the adhesion can be 1.1 N / cm, 1.15 N / cm, 1.2 N / cm, 1.25 N / cm, 1.28 N / cm, 1.3 N / cm, 1.32 N / cm, 1.35 N / cm, 1.37 N / cm, 1.38 N / cm, 1.39 N / cm, or 1.40 N / cm or above; the upper limit of the adhesion can be 2.4 N / cm, 2.3 N / cm, 2.25 N / cm, 2.2 N / cm, 2.15 N / cm, 2.1 N / cm, 2.05 N / cm, 2.03 N / cm, or 2.00 N / cm or below.

[0041] The adhesion force can be measured by cutting a polyimide film on an amorphous silicon substrate into 100×10mm pieces and using an INSTRON Model 5546 Universal Testing Machine (UTM) under conditions of 90° peel mode and a crosshead speed of 50mm / min.

[0042] The coefficient of thermal expansion (CTE) of polyimide films can range from 1 ppm / ℃ to 10 ppm / ℃. For example, the lower limit of CTE can be 1.5 ppm / ℃, 1.8 ppm / ℃, 2.0 ppm / ℃, 2.3 ppm / ℃, 2.5 ppm / ℃, 2.7 ppm / ℃, 3.0 ppm / ℃, 3.2 ppm / ℃, 3.3 ppm / ℃, 3.4 ppm / ℃, or 3.5 ppm / ℃ or above; the upper limit of CTE can be 9.7 ppm / ℃, 9.5 ppm / ℃, 9.4 ppm / ℃, 9.3 ppm / ℃, 9.2 ppm / ℃, 9.1 ppm / ℃, 9.0 ppm / ℃, 8.9 ppm / ℃, or 8.8 ppm / ℃ or below.

[0043] CTE can be obtained using a thermomechanical analyzer. Specifically, a polyimide film can be cut into pieces with a width of 5 mm and a length of 16 mm. Then, under a nitrogen atmosphere, the temperature is raised from room temperature to 470 °C at a heating rate of 10 °C / min while a tension of 0.02 N is applied. The film is then cooled again at a rate of 10 °C / min, and the slope is measured in the range of 100 °C to 460 °C.

[0044] The 1% thermal decomposition temperature (Td) of the polyimide film can be 300°C to 600°C, 350°C to 600°C, 400°C to 600°C, 450°C to 600°C, 500°C to 600°C, or 550°C to 600°C.

[0045] The 1% thermal decomposition temperature (Td) can be measured using a thermogravimetric analyzer. Specifically, the polyimide film can be heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, held isothermally for 30 minutes to remove moisture, and then heated to 600°C at a rate of 10°C / min to measure the temperature at which a 1% weight loss occurs.

[0046] Another embodiment of this disclosure provides a display comprising a polyimide film.

[0047] [Invention Method] Examples are provided to aid in understanding this disclosure. These examples are provided merely to facilitate a better understanding of this disclosure, and the scope of this disclosure is not limited to these examples.

[0048] <Example: Preparation of polyimide film> Example 1 The solution was prepared by mixing 100 mol% of the environmentally friendly solvent dimethylpropionamide (DMPA) with biphenyl dianhydride (BPDA) in a reactor.

[0049] Subsequently, 97 mol% of 1,4-diaminobenzene (PPD) and 3 mol% of 3,4'-diaminodiphenyl ether (3,4'-ODA) were added to the solution. The resulting mixture was then mixed and reacted at 25°C for 16 hours to prepare a polyimide precursor comprising polyamic acid and an environmentally friendly solvent (DMPA). Here, the dianhydride monomer (BPDA) and the diamine monomer (PPD and 3,4'-ODA) are used in equimolar amounts. Specifically, based on a total of 100 mol% of the diamine monomer, the total amount of dianhydride monomer used is 100 mol%.

[0050] Subsequently, by calculating the solvent-to-solids ratio to set an appropriate spin speed and time, the polyimide precursor was applied to the amorphous silicon sacrificial layer substrate using a spin coater. The temperature was then increased from 120°C to 470°C at a rate of 10°C / min, held at 470°C for 45 minutes, and then cooled to 25°C for curing, thus obtaining the polyimide film. At this point, the resulting film had a thickness of 10 μm.

[0051] Example 2 and Example 3 Polyimide films were prepared using the same method as in Example 1, except that the amounts of each monomer were different, as shown in Table 1 below.

[0052] Comparative Examples 1 to 8 Polyimide films were prepared using the same method as in Example 1, except that the amount and type of monomers were different, as shown in Table 1 below.

[0053] Table 1 below lists the types and amounts of monomers used in the preparation of the polyimide films according to Examples 1 to 3 and Comparative Examples 1 to 8, as well as the thickness of the prepared polyimide films.

[0054] Table 1

[0055] The abbreviations for the substances used in Table 1 above are as follows: BPDA: Biphenyltetracarboxylic dianhydride PPD: 1,4-Diaminobenzene 3,4'-ODA: 3,4'-Diaminodiphenyl ether 4,4'-ODA: 4,4'-Diaminodiphenyl ether TFMB: 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl m-Tb: 2,2'-dimethyl-4,4'-diaminobiphenyl <Experimental Example: Evaluation of the Physical Properties of Polyimide Films> Experimental Example 1: Appearance of Polyimide Film The appearance of the polyimide films prepared in the examples and comparative examples was evaluated by visually inspecting the surface to check for the presence of bubbles, and the results are shown in Table 2 according to the following criteria.

[0056] ○: The 110×110mm glass substrate is free of bubbles (good appearance). ×: Three or more air bubbles on a 110×110mm glass substrate (defective appearance) Experiment Example 2: Adhesion Force Measurement The adhesion of the polyimide films prepared in the examples and comparative examples to polyimide-coated substrates was measured. Polyimide films on amorphous silicon substrates were cut into 100 × 10 mm pieces, and the adhesion was measured using an INSTRON Model 5546 Universal Testing Machine (UTM) in 90° peel mode and at a crosshead speed of 50 mm / min. The measurement results are shown in Table 2 below.

[0057] Experimental Example 3: Measurement of Coefficient of Thermal Expansion (CTE) The coefficient of thermal expansion (CTE) was measured using a Q400 TA thermomechanical analyzer. The polyimide films prepared in the examples and comparative examples were cut into pieces 5 mm wide and 16 mm long. Under a nitrogen atmosphere, the temperature was raised from room temperature to 470 °C at a heating rate of 10 °C / min while a tension of 0.02 N was applied. The films were then cooled again at a rate of 10 °C / min, and the slope was measured from 100 °C to 460 °C. The measurement results are shown in Table 2 below.

[0058] Experimental Example 4: Measurement of 1% thermal decomposition temperature (1%Td) A TA Q50 thermogravimetric analyzer (TGA) was used. The polyimide films prepared in the examples and comparative examples were 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. The temperature was then increased to 600°C at a rate of 10°C / min, and the temperature at which a 1% weight loss occurred was measured. The results are shown in Table 2.

[0059] Table 2 summarizes the appearance, adhesion, CTE, and 1% thermal decomposition temperature (1% Td) of the polyimide films prepared in Examples 1 to 3 and Comparative Examples 1 to 8.

[0060] Table 2

[0061] According to Table 2, it can be confirmed that the polyimide films of Examples 1 to 3, which include a small amount (3 mol% to 20 mol%) of 3,4'-ODA, exhibit excellent adhesion compared to cases that do not include the second diamine monomer (Comparative Example 1), include a small amount of other diamine monomers (4,4'-ODA, TFMB, m-Tb) as the second diamine monomer (Comparative Examples 2 to 7), or include an excess (25 mol%) of 3,4'-ODA (Comparative Example 8).

[0062] In addition, it can be confirmed that the polyimide films of Examples 1 to 3 have excellent appearance (no bubbles) and heat resistance.

[0063] Specifically, when comparing Examples 1 and 2, which use the same amounts of 3,4'-ODA and 4,4'-ODA, with Comparative Examples 2 and 3, it can be confirmed that the polyimide film including 3,4'-ODA has a lower CTE and a higher 1% thermal decomposition temperature.

[0064] This is because the structure of 3,4'-ODA forms more linear polymer chains than 4,4'-ODA, thus exhibiting the effect of increasing the packing density of polymer chains during thermosetting. With increasing packing density, polyimide films including 3,4'-ODA exhibit higher substrate adhesion and excellent heat resistance.

[0065] Detailed descriptions of matters that are obvious and readily inferred by those skilled in the art are omitted herein. Furthermore, various modifications can be made beyond the specific embodiments described herein without altering the technical spirit or basic configuration of the invention. Therefore, this disclosure can be implemented in ways other than those specifically described and exemplified herein, as will be apparent to those skilled in the art.

Claims

1. A polyimide precursor, comprising: Polyamic acid, wherein the polyamic acid comprises a dianhydride monomer and a diamine monomer as polymerization units; and Environmentally friendly solvents The diamine monomer comprises a first diamine monomer and a second diamine monomer, the first diamine monomer and the second diamine monomer being different from each other, the second diamine monomer comprising 3,4'-diaminodiphenyl ether (3,4'-ODA), and based on 100 mol% of the total diamine monomers, the diamine monomer comprises 80 mol% to 99.9 mol% of the first diamine monomer and 0.01 mol% to 20 mol% of the second diamine monomer.

2. The polyimide precursor according to claim 1, wherein, The environmentally friendly solvent includes at least one selected from the group consisting of: dimethylpropionamide (DMPA), 3-methoxy-N,N-dimethylpropionamide, tetramethylurea (TMU), N-ethyl-2-pyrrolidone (NEP) and diethylformamide (DEF).

3. The polyimide precursor according to claim 1, wherein, The dianhydride monomer comprises at least one selected from the group consisting of: biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), biphenyl ether dianhydride (ODPA), diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride (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, bis(3,4-dicarboxyphenyl)methane dianhydride, and 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride. p-Phenylidene bis(triphenyltriacrylic acid anhydride), p-Biphenyl bis(triphenyltriacrylic acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride.

4. The polyimide precursor according to claim 3, wherein, The dianhydride monomer includes BPDA.

5. The polyimide precursor according to claim 1, wherein, The first diamine monomer comprises at least one selected from the group consisting of: 1,4-diaminobenzene (PPD), 4,4'-diaminodiphenyl ether (4,4'-ODA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (meta-toluidine), 2,2-bis(aminophenoxyphenyl)propane (BAPP), m-phenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobenzidine, and 3,3'-dimethyl-4,4'-diaminobenzidine. 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzoylaniline, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-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'-dimethoxy Benzophenone, 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, 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'-bis(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-aminophenyl sulfone)benzene, 1,3-bis(4-aminophenyl sulfone)benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-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[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]ketone [Phenylacetyl] 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[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 [4-aminophenoxyphenyl]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.

6. The polyimide precursor according to claim 5, wherein, The first diamine monomer includes PPD.

7. The polyimide precursor according to claim 1, wherein, The dianhydride monomer is BPDA, the first diamine monomer is PPD, and the second diamine monomer is 3,4'-ODA.

8. A method for preparing a polyimide precursor, the method comprising: The preparation of polyamic acid involves polymerizing dianhydride monomers and diamine monomers in an environmentally friendly solvent, thereby preparing a polyimide precursor comprising polyamic acid and an environmentally friendly solvent. The diamine monomer comprises a first diamine monomer and a second diamine monomer, the first diamine monomer and the second diamine monomer being different from each other, the second diamine monomer comprising 3,4'-diaminodiphenyl ether (3,4'-ODA), and based on 100 mol% of the total diamine monomers, the diamine monomer comprises 80 mol% to 99.9 mol% of the first diamine monomer and 0.01 mol% to 20 mol% of the second diamine monomer.

9. The method according to claim 8, wherein, The steps for preparing the polyimide precursor include: (a) The step of preparing a solution by mixing the dianhydride monomer into an environmentally friendly solvent; and (b) Add a first diamine monomer to the solution and then add a second diamine monomer, mix the resulting mixture, and react the resulting mixture to prepare a solution comprising polyamic acid.

10. The method according to claim 9, wherein, The reaction in step (b) was carried out at room temperature (20°C to 25°C) for 4 to 24 hours.

11. A polyimide film comprising a cured product of the polyimide precursor according to claim 1.

12. The polyimide film according to claim 11, wherein, The thickness of the polyimide film is from 1 μm to 100 μm.

13. The polyimide film according to claim 11, wherein, The polyimide film has an adhesion force of 1.0 N / cm to 2.5 N / cm to the amorphous silicon substrate.

14. The polyimide film according to claim 11, wherein, The coefficient of thermal expansion of the polyimide film is from 1 ppm / ℃ to 10 ppm / ℃.

15. The polyimide film according to claim 11, wherein, The 1% thermal decomposition temperature (Td) of the polyimide film is between 300°C and 600°C.

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