Polyimide precursor comprising eco-friendly solvent, and polyimide film having excellent substrate adhesion and excellent heat resistance properties manufactured therefrom

Abstract

The present invention provides a polyimide precursor comprising: a polyamic acid comprising a dianhydride monomer and a diamine monomer as polymerization units; and an eco-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 are different from each other, the second diamine monomer comprises 3,4'-diaminodiphenyl ether (3,4'-ODA), and the diamine monomer comprises 80 to 99.9 mol% of the first diamine monomer and 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomer.

Description

Technology Field

[0001] The present invention relates to a polyimide precursor containing an eco-friendly solvent and a polyimide film having excellent substrate adhesion and excellent heat resistance produced therefrom. More specifically, the invention relates to a polyimide precursor containing 3,4'-diaminodiphenyl ether (3,4'-ODA) and a polyimide film having excellent substrate adhesion and excellent heat resistance produced therefrom. Background Technology

[0002] In general, polyimide (PI) is a polymer material based on imide rings with excellent chemical stability and a rigid aromatic main chain. It possesses the highest levels of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials and can be manufactured into various forms such as films, fibers, and membranes. Due to these characteristics, polyimide is widely used in advanced materials and insulating coatings in the fields of electrical and electronic, semiconductor, display, automotive, aerospace, and space materials.

[0003] In particular, for use in displays, it must be transparent, and in order to reduce the defect rate caused by residual stress on the substrate during the heat treatment process for display manufacturing, there is a problem that the coefficient of thermal expansion must not be negative at temperatures above 350°C. In addition, for polyimide to be used for displays, it must have excellent adhesion to silicon wafers, glass, or metal.

[0004] Meanwhile, polyimides can be prepared by dissolving an acid dianhydride, which has two acid anhydride groups in its molecule, and a diamine, which has two amino groups in its molecule, in a solvent, synthesizing a polyimide precursor called a polyamic acid (PAA), followed by coating, drying, and heat treatment at a temperature of approximately 350°C to induce imidization. In this process, the polyimide is prepared using solvents currently classified as hazardous, such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc). NMP is a particularly excellent solvent for certain polyimides or polyamic acid polymers, dissolving those polymers that other solvents cannot dissolve. However, NMP is a reproductive toxicant or a reprotoxin. In the electronics industry, many polymer applications require spin coating, slot-die coating, or other deposition techniques where the polymer must remain in solution until the solvent is removed to cast the film, and the viscosity of such polymer compositions must be suitable for such deposition techniques. Such requirements present a problem in that they limit the range of available solvent choices for polyimides. There is a need for suitable solvents to replace NMP for use with polyimides in the manufacture of electronic devices.

[0005] Therefore, there is a need to develop polyimides that maintain the basic properties of current polyimides while possessing high substrate adhesion and excellent heat resistance, and are manufactured using a suitable solvent to replace NMP. The problem to be solved

[0006] The present invention aims to provide a polyimide precursor and a polyimide film produced therefrom, which utilize an eco-friendly solvent and possess excellent appearance (no bubbles), high substrate adhesion, and excellent heat resistance.

[0007] In addition, the present invention aims to provide a transparent polyimide precursor for displays and a polyimide film produced therefrom. means of solving the problem

[0008] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be illustrated and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0009] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0010] Where in this specification, when a quantity, concentration, or other value or parameter is given as an enumeration of a range, a preferred range, a preferred upper limit, and a preferred lower limit, it should be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value are specifically disclosed, regardless of whether the range is disclosed separately.

[0011] Where a range of numerical values ​​is mentioned in this specification, unless otherwise stated, the range and the scope of the parent invention within that range are not intended to be limited to the specific value mentioned when defining the range.

[0012] In this specification, "dianhydride" is intended to include its precursor or derivative, and is also referred to as "dianhydride acid," "dianhydride," or "acid dianhydride." Although these may not technically be dianhydrides, they will nevertheless react with a diamine to form a polyamic acid, which can then be converted into a polyimide.

[0013] In this specification, "diamine" is intended to include its precursors or derivatives, which may not technically be diamines but nevertheless will react with dianhydric acid to form a polyamic acid, which can then be converted into a polyimide.

[0014] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application. Specific details for the implementation of the above invention are described below.

[0015] The present invention relates to a polyimide precursor containing an eco-friendly solvent and a polyimide film produced therefrom having excellent substrate adhesion and excellent heat resistance.

[0016] polyimide precursor

[0017] The present invention provides a polyimide precursor comprising: a polyamic acid comprising a dianhydride monomer and a diamine monomer as polymerization units; and an eco-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 are different from each other, the second diamine monomer comprises 3,4'-diaminodiphenyl ether (3,4'-ODA), and the diamine monomer comprises 80 to 99.9 mol% of the first diamine monomer and 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomer.

[0018] Specifically, the diamine monomer may contain 80 to 99.9 mol% of the first diamine monomer based on 100 mol% of the total diamine monomer, 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, and 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.

[0019] The above diamine monomer may contain 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomer, 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, and 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.

[0020] Based on a total of 100 mol% of diamine monomers, if the first diamine monomer is less than 80 mol% (the second diamine monomer is more than 20 mol%), the substrate adhesion of the manufactured polyimide film is low and the heat resistance is poor, which is undesirable, and if the first diamine monomer is more than 99.9 mol% (the second diamine monomer is less than 0.01 mol%), the substrate adhesion and heat resistance of the manufactured polyimide film are poor and are undesirable.

[0021] The above-mentioned eco-friendly solvent may include one or more selected from the group consisting of dimethylpropionamide (DMPA), 3-methoxy-N,N-dimethylpropanamide, tetramethyl urea (TMU), N-ethyl-2-pyrrolidone (NEP), and diethyl formamide (DEF), and preferably may include dimethylpropionamide (DMPA). The DMPA is an eco-friendly organic solvent that can be processed without undergoing a separate purification process after the polymerization reaction, thereby providing a cost-saving effect.

[0022] The above dianhydric monomers are biphenyl tetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), diphenylsulfone-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-phenylenebis(trimelytic monoester acid anhydride), p-biphenylenebis(trimelytic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalene tetracarboxylic acid dianhydride, 1,4,5,8-naphthalene tetracarboxylic It may include one or more selected from the group consisting of dianhydride and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride, and preferably may include biphenyl tetracarboxylic dianhydride (BPDA).

[0023] The above first diamine monomer is 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 (m-tolidine), 2,2-bisaminophenoxyphenylpropane (BAPP), metaphenylenediamine, 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'-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 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)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'-Diaminodiphenylsulfoxide, 3,4'-Diaminodiphenylsulfoxide, 4,4'-Diaminodiphenylsulfoxide, 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-aminophenylsulfide)benzene, 1,3-Bis(4-aminophenylsulfide)benzene, 1,4-Bis(4-aminophenylsulfide)benzene, 1,3-Bis(3-aminophenylsulfone)benzene, 1,3-Bis(4-aminophenylsulfone)benzene, 1,4-Bis(4-aminophenylsulfone)benzene, 1,3-Bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-Bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-Bis[2-(4-aminophenyl)isopropyl]benzene, 3,3'-Bis(3-aminophenoxy)biphenyl, 3,3'-Bis(4-aminophenoxy)biphenyl, 4,4'-Bis(3-aminophenoxy)biphenyl, 4,4'-Bis(4-aminophenoxy)biphenyl, Bis[3-(3-aminophenoxy)phenyl]ether, Bis[3-(4-aminophenoxy)phenyl]ether, Bis[4-(3-aminophenoxy)phenyl]ether, Bis[4-(4-aminophenoxy)phenyl]ether, Bis[3-(3-aminophenoxy)phenyl]ketone, Bis[3-(4-aminophenoxy)phenyl]ketone, Bis[4-(3-aminophenoxy)phenyl]ketone, Bis[4-(4-aminophenoxy)phenyl]ketone, Bis[3-(3-aminophenoxy)phenyl]sulfide, Bis[3-(4-aminophenoxy)phenyl]sulfide, Bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]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,It may include one or more selected from the group consisting of 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, preferably one or more 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) and 2,2'-dimethyl-4,4'-diaminobiphenyl (m-tolidine), more preferably 1,4-diaminobenzene (PPD). When the first diamine monomer comprises 1,4-diaminobenzene (PPD), the polyimide film produced from the polyimide composition has the effect of having excellent heat resistance properties.

[0024] More preferably, the dianhydride monomer may be biphenyl tetracarboxylic dianhydride (BPDA), the first diamine monomer may be 1,4-diaminobenzene (PPD), and the second diamine monomer may be 3,4'-diaminodiphenyl ether (3,4'-ODA). When the dianhydride monomer is biphenyl tetracarboxylic dianhydride (BPDA), the first diamine monomer is 1,4-diaminobenzene (PPD), and the second diamine monomer is 3,4'-diaminodiphenyl ether (3,4'-ODA), the polyimide film produced from the polyimide composition has the effect of having excellent heat resistance properties.

[0025] The molar ratio of the above dianhydride monomer to the above diamine monomer may be 1:2 to 2:1, and preferably 1:1.

[0026] The above polyamic acid may contain 95 to 105 mol% of the dianhydride monomer based on 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.

[0027] Another embodiment of the present invention provides a method for manufacturing the polyimide precursor.

[0028] Method for manufacturing a polyimide precursor

[0029] The present invention provides a method for preparing a polyimide precursor comprising the step of polymerizing a dianhydride monomer and a diamine monomer in an eco-friendly solvent to produce a polyamic acid, and preparing a polyimide precursor comprising the polyamic acid and the eco-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 are different from each other, the second diamine monomer comprises 3,4'-diaminodiphenyl ether (3,4'-ODA), and the diamine monomer comprises 80 to 99.9 mol% of the first diamine monomer and 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomer.

[0030] Specifically, the diamine monomer may contain 80 to 99.9 mol% of the first diamine monomer based on 100 mol% of the total diamine monomer, 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, and 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.

[0031] The above diamine monomer may contain 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomer, 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, and 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.

[0032] Based on a total of 100 mol% of diamine monomers, if the first diamine monomer is less than 80 mol% (the second diamine monomer is more than 20 mol%), the substrate adhesion of the manufactured polyimide film is low and the heat resistance is poor, which is undesirable, and if the first diamine monomer is more than 99.9 mol% (the second diamine monomer is less than 0.01 mol%), the substrate adhesion and heat resistance of the manufactured polyimide film are poor and are undesirable.

[0033] The step of preparing the above polyimide precursor may include: (a) a step of preparing a solution by mixing a dianhydride monomer in an eco-friendly solvent; and (b) a step of preparing a solution containing polyamic acid by adding a first diamine monomer to the solution, then adding and mixing a second diamine monomer, and reacting the mixture.

[0034] The reaction of step (b) can be carried out at room temperature (20 to 25°C) for 4 to 24 hours, preferably for 8 to 20 hours, more preferably for 12 to 18 hours, and even more preferably for 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 a solution containing polyamic acid can be efficiently prepared in terms of the increase in the production of polyamic acid over time.

[0035] Another embodiment of the present invention provides a polyimide precursor prepared by the method for preparing the polyimide precursor.

[0036] polyimide film

[0037] The present invention provides a polyimide film comprising a cured product of the polyimide precursor.

[0038] The thickness of the above polyimide film can be appropriately selected considering the application, usage environment, physical properties, etc. of the polyimide film. For example, the thickness of the polyimide film may be 1 to 100 μm, 5 to 50 μm, 7 to 30 μm, 8 to 20 μm, or 9 to 15 μm, but is not limited thereto.

[0039] The adhesion strength of the above polyimide film to the a-Si substrate may be 1.0 to 2.5 N / cm, for example, the lower limit of the adhesion strength may 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 higher, and the upper limit of the adhesion strength may 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 lower.

[0040] The above adhesion strength may be measured by cutting a polyimide film on an a-Si substrate into 100x10mm pieces and using an INSTRON UTM 5546 model under 90° Peel mode and Cross Head Speed ​​50mm / min conditions.

[0041] The coefficient of thermal expansion (CTE) of the polyimide film may be 1 to 10 ppm / ℃, for example, the lower limit of the coefficient of thermal expansion may 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 higher, and the upper limit of the coefficient of thermal expansion may 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 lower.

[0042] The coefficient of thermal expansion (CTE) mentioned above may be obtained using a thermomechanical analyzer. Specifically, a polyimide film may be cut to a width of 5 mm and a length of 16 mm, and then heated from room temperature to 470°C at a heating rate of 10°C / min while applying a tension of 0.02 N under a nitrogen atmosphere, and then cooled again at a rate of 10°C / min while measuring the slope of the 100°C to 460°C range.

[0043] The 1% pyrolysis temperature (Td) of the above polyimide film may be 300 to 600°C, 350 to 600°C, 400 to 600°C, 450 to 600°C, 500 to 600°C, or 550 to 600°C.

[0044] The above 1% thermal decomposition temperature (Td) may be measured using a thermogravimetric analyzer. Specifically, the polyimide film may be heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, maintained 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.

[0045] Another embodiment of the present invention provides a display comprising the polyimide film. Effects of the invention

[0046] The polyimide precursor according to the present invention and the polyimide film produced therefrom utilize an eco-friendly solvent and have the effect of having an excellent appearance (no bubbles), high substrate adhesion, and excellent heat resistance.

[0047] Specifically, the polyimide precursor according to the present invention and the polyimide film produced therefrom include 3,4'-ODA, which forms a polymer chain having a more linear structure than 4,4'-ODA, thereby increasing the packing density of the polymer chain, and as the packing density increases, it has the effect of having higher substrate adhesion and excellent heat resistance.

[0048] In addition, the polyimide precursor according to the present invention and the polyimide film produced therefrom have the effect of being applicable to displays. Specific details for implementing the invention

[0049] Examples are provided to aid in understanding the present invention. The following examples are provided merely to facilitate a better understanding of the invention, and the scope of the invention is not limited by these examples.

[0050] <Example: Preparation of Polyimide Film>

[0051] Example 1

[0052] A solution was prepared by mixing 100 mol% of dimethylpropionamide (DMPA), an eco-friendly solvent, and biphenyl tetracarboxylic dianhydride (BPDA) in a reactor.

[0053] Subsequently, 97 mol% of 1,4-diaminobenzene (PPD) was added to the above solution, followed by the addition and mixing of 3 mol% of 3,4'-diaminodiphenyl ether (3,4'-ODA). The mixture was then reacted at 25°C for 16 hours to prepare a polyimide precursor containing polyamic acid and an eco-friendly solvent (DMPA). Here, the dianhydride monomer (BPDA) and the diamine monomers (PPD and 3,4'-ODA) are used in equimolar amounts. Specifically, the dianhydride monomer is used in a total of 100 mol% based on a total of 100 mol% of the diamine monomer.

[0054] Next, the polyimide precursor was coated onto an a-Si sacrificial layer substrate by using a spin coater to calculate the solvent-to-solid ratio and setting an appropriate rpm and time. Subsequently, a polyimide film was obtained by curing under conditions of increasing the temperature from 120°C to 470°C at a rate of 10°C / min, maintaining it at 470°C for 45 minutes, and then decreasing the temperature to 25°C. At this time, the film thickness was prepared to be 10 μm.

[0055] Examples 2 and 3

[0056] Polyimide films were prepared in the same manner as in Example 1, except that the monomer content was used differently as shown in Table 1 below.

[0057] Comparative Examples 1 to 8

[0058] Polyimide films were prepared in the same manner as in Example 1, except that the content and type of monomers were used differently, as shown in Table 1 below.

[0059] Table 1 below lists the type and content of monomers used to prepare polyimide films according to Examples 1 to 3 and Comparative Examples 1 to 8, and the thickness of the prepared polyimide films, respectively.

[0060] division dianhydride monomer 1st diamine Second diamine Thickness (㎛) type Content (Moll%) type Content (Moll%) type Content (Moll%) Example 1 BPDA 100 PPD 97 3,4'-ODA 3 10.0 Example 2 95 3,4'-ODA 5 10.0 Example 3 80 3,4'-ODA 20 10.2 Comparative Example 1 100 - - 10.0 Comparative Example 2 97 4,4'-ODA 3 9.9 Comparative Example 3 95 4,4'-ODA 5 10.2 Comparative Example 4 97 TFMB 3 9.9 Comparative Example 5 95 TFMB 5 9.7 Comparative Example 6 97 m-Tb 3 9.8 Comparative Example 7 95 m-Tb 5 9.7 Comparative Example 8 75 3,4'-ODA 25 10.0

[0061] The abbreviations of the substances used in Table 1 above are as follows.

[0062] BPDA: Biphenyl tetracarboxylic dianhydride

[0063] PPD: 1,4-diaminobenzene

[0064] 3,4'-ODA: 3,4'-diaminodiphenyl ether

[0065] 4,4'-ODA: 4,4'-diaminodiphenyl ether

[0066] TFMB: 2,2'-Bis(trifluoromethyl)-4,4'-Diaminobiphenyl

[0067] m-Tb: 2,2'-dimethyl-4,4'-diaminobiphenyl

[0069] <Experimental Example: Evaluation of Physical Properties of Polyimide Film>

[0070] Experimental Example 1. Verification of the appearance of the polyimide film

[0071] The appearance of the polyimide film was evaluated by visually inspecting the surface of the polyimide film prepared in the examples and comparative examples to check for the occurrence of bubbles, and the results are shown in Table 2 according to the criteria below.

[0072] ○: No air bubbles in 110 x 110mm glass substrate (Excellent appearance)

[0073] ×: 3 or more air bubbles in 110 x 110mm glass substrate (appearance defect)

[0074] Experimental Example 2. Measurement of Adhesion Strength

[0075] The adhesion strength of the polyimide films prepared in the examples and comparative examples for polyimide-coated substrates was measured. The adhesion strength was measured by cutting the polyimide film on an a-Si substrate into 100x10mm pieces and using an INSTRON UTM 5546 model under 90° Peel mode and Cross Head Speed ​​50mm / min conditions. The measurement results are shown in Table 2 below.

[0076] Experimental Example 3. Measurement of Coefficient of Thermal Expansion (CTE)

[0077] The coefficient of thermal expansion (CTE) was determined using a TA Q400 thermomechanical analyzer. The polyimide films prepared in the above examples and comparative examples were cut to a width of 5 mm and a length of 16 mm. Then, under a nitrogen atmosphere, while applying a tension of 0.02 N, the films were heated from room temperature to 470°C at a heating rate of 10°C / min and then cooled at a rate of 10°C / min, and the slope of the temperature range from 100°C to 460°C was measured. The measurement results are shown in Table 2 below.

[0078] Experimental Example 4. Measurement of 1% Pyrolysis Temperature (1% Td)

[0079] The TA Q50 thermogravimetric analysis model was used, and the polyimide films prepared in the above examples and comparative examples were heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere and maintained isothermally for 30 minutes to remove moisture. Subsequently, the temperature was increased to 600°C at a rate of 10°C / min to measure the temperature at which a 1% weight loss occurred, and the results are shown in Table 2 below.

[0080] Table 2 below summarizes the appearance, adhesion, coefficient of thermal expansion (CTE), and 1% pyrolysis temperature (1% Td) values ​​of the polyimide films of Examples 1 to 3 and Comparative Examples 1 to 8.

[0081] division appearance Adhesion (N / cm) CTE (ppm / ℃) 1% Td (°C) Example 1 ○ 1.41 3.7 575 Example 2 ○ 1.89 5.5 577 Example 3 ○ 1.90 8.8 568 Comparative Example 1 × 0.22 5.0 569 Comparative Example 2 ○ 0.20 10.7 571 Comparative Example 3 ○ 0.21 11.0 571 Comparative Example 4 ○ 1.27 5.7 571 Comparative Example 5 ○ 0.01 10.0 564 Comparative Example 6 × 0.96 3.4 566 Comparative Example 7 ○ 0.96 6.8 563 Comparative Example 8 ○ 0.78 10.8 567

[0082] According to Table 2, it can be confirmed that the polyimide films of Examples 1 to 3 have superior adhesion compared to cases where the second diamine monomer is not included (Comparative Example 1), other diamine monomers (4,4'-ODA, TFMB, m-Tb) are included in small amounts as the second diamine monomer (Comparative Examples 2 to 7), or 3,4'-ODA is included in excess (25 mol%) (Comparative Example 8).

[0083] In addition, it can be confirmed that the polyimide films of Examples 1 to 3 possess excellent appearance (no bubbles) and heat resistance properties.

[0084] Specifically, when comparing Examples 1 and 2 with Comparative Examples 2 and 3, in which 3,4'-ODA and 4,4'-ODA of the same content were used, it can be seen that the polyimide film containing 3,4'-ODA has a lower coefficient of thermal expansion (CTE) and a higher 1% pyrolysis temperature.

[0085] This is because the structure of 3,4'-ODA forms polymer chains with a more linear structure than that of 4,4'-ODA, which has the effect of increasing the packing density of the polymer chains during heat curing. As the packing density increases, polyimide films containing 3,4'-ODA have the effect of having higher substrate adhesion and excellent heat resistance.

[0087] The specification omits detailed descriptions of matters that can be sufficiently recognized and inferred by those skilled in the art of the present invention, and various modifications are possible within the scope of not altering the technical concept or essential configurations of the present invention, in addition to the specific examples described in this specification. Accordingly, the present invention may be implemented in a manner different from that specifically described and exemplified in this specification, and this is a matter that can be understood by those skilled in the art.

Claims

Claim 1 A polyimide precursor comprising: a polyamic acid containing a dianhydride monomer and a diamine monomer as polymerization units; and an eco-friendly solvent; wherein the dianhydride monomer is biphenyl tetracarboxylic dianhydride (BPDA), the diamine monomer comprises a first diamine monomer and a second diamine monomer, the first diamine monomer is 1,4-diaminobenzene (PPD), the second diamine monomer is 3,4'-diaminodiphenyl ether (3,4'-ODA), and the diamine monomer comprises 80 to 99.9 mol% of the first diamine monomer and 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomers. Claim 2 A polyimide precursor according to claim 1, wherein the eco-friendly solvent comprises one or more selected from the group consisting of dimethylpropionamide (DMPA), 3-methoxy-N,N-dimethylpropanamide, tetramethyl urea (TMU), N-ethyl-2-pyrrolidone (NEP), and diethyl formamide (DEF). Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 A method for preparing a polyimide precursor comprising: a step of preparing a polyamic acid by polymerizing a dianhydride monomer and a diamine monomer in an eco-friendly solvent to produce a polyamic acid, and preparing a polyimide precursor comprising the polyamic acid and the eco-friendly solvent; wherein the dianhydride monomer is biphenyl tetracarboxylic dianhydride (BPDA), the diamine monomer comprises a first diamine monomer and a second diamine monomer, the first diamine monomer is 1,4-diaminobenzene (PPD), the second diamine monomer is 3,4'-diaminodiphenyl ether (3,4'-ODA), and the diamine monomer comprises 80 to 99.9 mol% of the first diamine monomer and 0.01 to 20 mol% of the second diamine monomer based on 100 mol% of the total diamine monomers. Claim 9 A method for manufacturing a polyimide precursor according to claim 8, wherein the step of manufacturing the polyimide precursor comprises: (a) a step of preparing a solution by mixing a dianhydride monomer in an eco-friendly solvent; and (b) a step of preparing a solution containing polyamic acid by adding a first diamine monomer to the solution, then adding and mixing a second diamine monomer, and reacting the mixture. Claim 10 A method for preparing a polyimide precursor according to claim 9, wherein the reaction of step (b) is carried out at room temperature (20 to 25°C) for 4 to 24 hours. Claim 11 A polyimide film comprising a cured product of a polyimide precursor according to claim 1. Claim 12 In claim 11, a polyimide film having a thickness of 1 to 100 μm. Claim 13 A polyimide film according to claim 11, wherein the adhesion strength of the polyimide film to an a-Si substrate is 1.0 to 2.5 N / cm. Claim 14 In claim 11, a polyimide film having a coefficient of thermal expansion (CTE) of 1 to 10 ppm / ℃. Claim 15 In claim 11, the polyimide film having a 1% pyrolysis temperature (Td) of 300 to 600°C.