Polyamic acid composition for preparing soluble polyimide solution and soluble polyimide solution prepared therefrom

Abstract

The present invention provides a polyamic acid composition for preparing a soluble polyimide solution and a soluble polyimide solution prepared therefrom, the polyamic acid composition comprising a polyamic acid comprising, as polymerization units, a dianhydride monomer and a diamine monomer, wherein the dianhydride monomer includes bisphenol A dianhydride (BPADA) and biphenyl tetracarboxylic dianhydride (BPDA), and the diamine monomer includes 2,2'-bis(trifluoromethyl)benzidine (TFMB).

Description

Polyamic acid composition for preparing an available polyimide solution and an available polyimide solution prepared therefrom

[0001] The present invention relates to a polyamic acid composition for preparing a soluble polyimide solution and a soluble polyimide solution prepared therefrom. Specifically, the present invention relates to a polyimide (film, hollow fiber membrane, powder, etc.) having excellent optical, thermal, and mechanical properties while simplifying the process.

[0002] The present invention relates to a polyamic acid composition for preparing a soluble polyimide solution, particularly suitable for use as a display substrate, and to a soluble polyimide solution prepared therefrom.

[0003] In general, polyimide (PI) is a polymer material with the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials based on an imide ring with excellent chemical stability along with a rigid aromatic main chain, and it can be manufactured into various forms such as films, fibers, and membranes. Due to these characteristics, polyimide is widely used in a wide range of fields as an advanced material and insulating coating agent in the fields of electrical and electronics, semiconductors, displays, automobiles, aviation, and space materials. Recently, as various electronic devices have become thinner, lighter, and smaller, a lot of research is being conducted to use thin polyimides with excellent flexibility as insulating materials for circuit boards or as display substrates that can replace glass substrates for displays.

[0004] Meanwhile, polyimide can be manufactured by dissolving an acid dianhydride having two acid anhydride groups per molecule and a diamine having two amino groups per molecule in a solvent, synthesizing a polyimide precursor called polyamic acid (PAA), followed by coating, drying, and heat treating at a temperature of about 350°C to imidize. However, polyamic acid solutions are easily affected by humidity, are difficult to handle and store, and have the problem of requiring a high-temperature heat treatment process or a complicated and long-time treatment process to imidize polyamic acid. In addition, polyimides manufactured by imidization through dehydration and ring closure reactions using conventional chemical methods or thermal (high-temperature) methods have the problem of being difficult to process due to their insolubility in solvents.

[0005] Accordingly, there has been a growing demand for handling polyimides in solution form, leading to extensive development of solvent-soluble polyimides. However, to manufacture solvent-soluble polyimides, the use of highly soluble monomers is generally unavoidable. However, these monomers generally have low heat resistance, resulting in polyimides with poor heat and chemical resistance.

[0006] Against this backdrop, there is a need to develop a polyimide that has optical, thermal, and mechanical properties suitable for display substrates, is easily soluble in organic solvents, and enables the manufacture of polyimide-based products through a simple process.

[0007] The purpose of the present invention is to provide a polyamic acid composition for preparing a polyimide solution having a soluble property in an organic solvent after the polyimide is fully imidized, and a polyimide solution prepared therefrom.

[0008] In addition, the present invention aims to provide a polyamic acid composition for preparing a polyimide solution for preparing a polyimide having excellent optical, mechanical, and thermal properties while simplifying the manufacturing process by omitting the purification, filtration, and drying processes for removing by-products (impurities), and a polyimide solution prepared therefrom.

[0009] In addition, the present invention aims to provide a polyamic acid composition for preparing the above-described available polyimide solution and a polyimide solution prepared therefrom in various forms such as a varnish, a film, a hollow fiber membrane, a powder, etc.

[0010] In addition, the present invention aims to provide a polyamic acid composition for preparing a soluble polyimide solution, which is particularly suitable for use as a display substrate, and a soluble polyimide solution prepared therefrom.

[0011] The present invention is susceptible to various modifications and embodiments. Therefore, specific embodiments are illustrated and described in detail. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0012] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0013] When amounts, concentrations, or other values ​​or parameters are given herein as a range, preferred range, or enumeration of an upper preferred value and a lower preferred value, it should be understood that this specifically discloses any range formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed.

[0014] When a range of numerical values ​​is mentioned in this specification, unless otherwise stated, it is intended that the endpoints of the range and the scope of the invention within the range are not limited to the specific values ​​mentioned in defining the range.

[0015] As used herein, "dianhydride" is intended to include precursors or derivatives thereof, also referred to as "dianhydric acids," "dianhydrides," or "acid dianhydrides." While these may not technically be dianhydrides, they will nonetheless react with diamines to form polyamic acids, which can then be converted to polyimides.

[0016] As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but which will nonetheless react with a dianhydride acid to form a polyamic acid, which in turn can be converted to a polyimide.

[0017] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be construed in an idealized or overly formal sense unless explicitly defined herein. Specific details for implementing the invention are described below.

[0018] The present invention relates to a polyamic acid composition for preparing an available polyimide solution and a soluble polyimide solution prepared therefrom.

[0019] In the present invention, the available polyimide solution means a varnish (solution) in which a fully imidized solid polyimide is dissolved in an organic solvent.

[0020] Polyamic acid composition for preparing available polyimide solution

[0021] The present invention provides a polyamic acid composition for preparing a soluble polyimide solution, which comprises a polyamic acid comprising a dianhydride monomer and a diamine monomer as polymerization units, wherein the dianhydride monomer comprises bisphenol A dianhydride (BPADA) and biphenyl tetracarboxylic dianhydride (BPDA), and the diamine monomer comprises 2,2'-bis(trifluoromethyl)benzidine (TFMB).

[0022] The polyamic acid composition for preparing the above-mentioned available polyimide solution may additionally contain carbonyl diimidazole.

[0023] In the past, a tertiary amine was used as a catalyst and acetic anhydride as a dehydrating agent, and in order to remove by-products during chemical imidization, a purification process such as purification, washing, filtration and drying was performed to obtain a powder form, which was then dissolved in a polar organic solvent for use. However, the present invention uses an additive CDI having both a catalyst and a dehydrating agent function, thereby omitting the purification process including purification, filtration and drying, and can be used directly in the form of a varnish.

[0024] For example, when producing a polyimide film through thermal imidization, a high temperature (over 350°C) process was previously required, but the present invention can produce a polyimide film by only drying the solvent at a low temperature (under 250°C) using a fully imidized varnish-type available polyimide solution.

[0025] The polyamic acid composition for preparing the above-described available polyimide solution may contain 0.5 to 1.5 mol% of the carbonyl diimidazole based on 1 molar equivalent of the polyamic acid. For example, the upper limit may be 1.4 mol%, 1.3 mol%, 1.25 mol%, 1.2 mol%, 1.15 mol%, 1.12 mol%, 1.11 mol%, 1.1 mol%, 1.09 mol%, 1.08 mol%, 1.07 mol%, 1.06 mol%, or 1.05 mol% or less, and the lower limit may be 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.8 mol%, 0.85 mol%, 0.87 mol%, 0.88 mol%, 0.89 mol%, or 0.9 mol% or more. The polyamic acid composition for preparing the above-mentioned soluble polyimide solution contains 0.5 to 1.5 mol% of the above-mentioned carbonyl diimidazole with respect to 1 molar equivalent of the above-mentioned polyamic acid, so that the mechanical and thermal properties of the polyimide (film, hollow fiber membrane, powder, etc.) finally prepared therefrom are excellent, and there is an effect that no additional purification process is required after preparing the above-mentioned soluble polyimide solution.

[0026] The bisphenol A dianhydride (BPADA) content among the total dianhydride monomers may be 60 mol% or more and less than 100 mol%. For example, the upper limit may be 99 mol%, 98 mol%, 97 mol%, 96 mol%, or 95 mol% or less, and the lower limit may be 60 mol%, 65 mol%, 70 mol%, 75 mol%, 77 mol%, 78 mol%, 79 mol%, or 80 mol% or more. When the bisphenol A dianhydride (BPADA) content is included outside the above range (60 mol% or more and less than 100 mol%), it is difficult to manufacture a polyimide (film, hollow fiber membrane, powder, etc.) having the desired optical, mechanical, and thermal properties, which is not preferable.

[0027] The biphenyl tetracarboxylic dianhydride (BPDA) content among the total dianhydride monomers may be greater than 0 mol% and less than or equal to 40 mol%. For example, the upper limit may be less than or equal to 40 mol%, 35 mol%, 30 mol%, 25 mol%, 23 mol%, 22 mol%, 21 mol%, or 20 mol%, and the lower limit may be greater than or equal to 1 mol%, 2 mol%, 3 mol%, 4 mol%, or 5 mol%. When the biphenyl tetracarboxylic dianhydride (BPDA) content is included outside the above range (more than 0 mol% and less than or equal to 40 mol%), it is difficult to manufacture a polyimide (film, hollow fiber membrane, powder, etc.) having desired optical, mechanical, and thermal properties, which is not preferable.

[0028] The above diamine monomer may further include at least one second diamine selected from the group consisting of 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6-FAP), 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), methylenedianiline (MDA), 4-[2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl]aniline (HFDA), 2-amino-4-(3-amino-4-hydroxyphenyl)sulfonylphenol and bis[4-(3-aminophenoxy)phenyl]sulfone (m-BAPS). and preferably, 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA) may be additionally included as a second diamine.

[0029] When the above diamine monomer is additionally included, TFMB may be included in an amount of 20 to 80 mol%, 30 to 70 mol%, or 40 to 60 mol% of the total diamine monomer, and the second diamine may be included in an amount of 20 to 80 mol%, 30 to 70 mol%, or 40 to 60 mol%. When within the above range, there is an effect of being able to provide a polyimide (film, hollow fiber membrane, powder, etc.) having the desired optical, mechanical, and thermal properties.

[0030] The present invention can realize optical properties required for a display substrate while having solubility properties in organic solvents by including the specific monomer combination described above.

[0031] The polyamic acid composition for preparing the above-mentioned available polyimide solution may contain 90 to 110 mol% of the above-mentioned dianhydride monomer, preferably 95 to 105 mol%, and more preferably 100 mol%.

[0032] The polyamic acid composition for preparing the above-mentioned available polyimide solution may contain 90 to 110 mol% of the above-mentioned diamine monomer, preferably 95 to 105 mol%, and more preferably 100 mol%.

[0033] The polyamic acid composition for preparing the above-mentioned available polyimide solution may contain the above-mentioned dianhydride monomer and the above-mentioned diamine monomer in a molar ratio of 6:4 to 4:6, and preferably in a molar ratio of 5:5.

[0034] Available polyimide solution

[0035] The present invention provides a soluble polyimide solution prepared from the polyamic acid composition for preparing the above soluble polyimide solution.

[0036] Specifically, the present invention provides a soluble polyimide solution comprising a polyimide comprising a dianhydride monomer and a diamine monomer as polymerization units, wherein the dianhydride monomer comprises bisphenol A dianhydride (BPADA) and biphenyl tetracarboxylic dianhydride (BPDA), and the diamine monomer comprises 2,2'-bis(trifluoromethyl)benzidine (TFMB).

[0037] The above-mentioned soluble polyimide solution can be in the form of a varnish, and the above-mentioned soluble polyimide solution has the advantage of being readily usable in polyimide films, fibers or coatings by being used directly in the form of a varnish without a purification process including purification, filtration and drying steps.

[0038] The above-mentioned soluble polyimide solution may additionally contain imidazole. The above-mentioned soluble polyimide solution does not contain imidazole partially substituted with a substituent.

[0039] Specifically, a soluble polyimide solution prepared from a polyamic acid composition for preparing a soluble polyimide solution containing carbonyl diimidazole includes an imidazole compound, wherein the imidazole compound is a byproduct of the carbonyl diimidazole. The imidazole compound exists between the polyimide polymer chains and forms hydrogen bonds with the polyimide polymer chains, thereby improving intermolecular force and enhancing mechanical properties.

[0040] Meanwhile, when forming a film from an available polyimide solution, the imidazole compound is easily removed by heat and therefore does not remain in the finished polyimide product (film, hollow fiber membrane, powder, etc.).

[0041] This has the advantage of easy removal of by-products compared to the chemical imidization method using a conventional catalyst (tertiary amine) and dehydrating agent (acetic anhydride) and the process of purifying, washing, filtering, and drying.

[0042] The above-mentioned available polyimide solution may contain the imidazole compound in an amount of more than 0 parts by weight and less than or equal to 75 parts by weight, preferably more than or equal to 15 parts by weight and less than or equal to 55 parts by weight, and more preferably more than or equal to 20 parts by weight and less than or equal to 50 parts by weight, based on 100 parts by weight of the polyimide.

[0043] The polyimide described above has excellent solubility in organic solvents for solids content of 30 wt% or less. In one embodiment, the presence of floating matter in the soluble polyimide solution was visually confirmed. If no floating matter was present in the solution, it was judged to be soluble, and if floating matter was present in the solution, it was judged to be insoluble.

[0044] The above organic solvent may be an aprotic polar organic solvent, and specifically may include at least one selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), dimethylpropanamide (DMPA), and N,N-diethylacitamide (DEAc).

[0045] The monomers and their contents of the above-mentioned available polyimide solution are the same as those described above, so duplicate description is omitted.

[0046] In the present invention, in order to determine the optical properties of an available polyimide solution, it was manufactured in a film form and the light transmittance and yellow index (YI) were measured at 440 to 740 nm.

[0047] Specifically, the above light transmittance may be obtained by measuring the light transmittance at 440 to 740 nm using an ultraviolet / visible spectrophotometer (UV-Vis Spectrophotometer) and calculating the average value thereof. A film manufactured using the available polyimide solution of the present invention may have a light transmittance of 85% or more at 440 to 740 nm, and for example, the lower limit of the light transmittance may be 86%, 87%, 88%, or 89% or more, and the upper limit is not particularly limited, but may be 100% or less.

[0048] In addition, the yellowness can be measured with a Hunter Lab Color-meter. The film manufactured using the available polyimide solution of the present invention may have a yellowness of 1.50 or less, for example, the upper limit of the yellowness may be 1.48 or less, 1.47 or less, 1.46 or less, 1.45 or less, 1.44 or less, 1.43 or less, 1.42 or less, or 1.41 or less, and the lower limit is not particularly limited, but may be 0.5 or more.

[0049] In addition, the film manufactured using the above-mentioned available polyimide solution may have a modulus of 2.8 GPa or more, preferably 2.9 GPa or more, and the upper limit is not particularly limited but may be 30.0 GPa or less. The above-mentioned modulus may be measured using an Instron 5564 UTM device from INSTRON.

[0050] The film manufactured using the above-mentioned available polyimide solution may have a tensile strength of 100 MPa or more, preferably 103 MPa, 104 MPa, 105 MPa or 106 MPa or more, and the upper limit is not particularly limited but may be 400 MPa or less. The tensile strength may be measured using an Instron 5564 UTM device manufactured by INSTRON.

[0051] The film manufactured using the above-mentioned available polyimide solution may have an elongation of 7% or more, preferably 7.5%, 7.6%, 7.65%, 7.67%, 7.68%, 7.69%, 7.7% or 7.71% or more, and the upper limit is not particularly limited but may be 30% or less. The above-mentioned elongation may be measured using an Instron 5564 UTM device manufactured by INSTRON.

[0052] In the present invention, the thermal decomposition temperature (Td), which is mainly used as a standard for judging the thermal properties of an available polyimide solution, and the glass transition temperature (Tg), which can predict the thermal properties while also ensuring the mechanical properties, were confirmed.

[0053] The glass transition temperature (Tg) of the above-mentioned soluble polyimide solution may be 230°C or higher, and for example, the lower limit of the glass transition temperature may be 231°C or 232°C or higher, and the upper limit is not particularly limited but may be 500°C or lower. The above-mentioned glass transition temperature may be measured using DMA at 5°C / min for the soluble polyimide solution.

[0054] The 5 wt% thermal decomposition temperature (Td) of the above-mentioned available polyimide solution may be 510°C or higher, and for example, the lower limit of the thermal decomposition temperature may be 511°C or 512°C or higher, and the upper limit is not particularly limited but may be 600°C or lower. The thermal decomposition temperature may be measured using a TA thermogravimetric analysis Q50 model. In a specific example, the polyimide is heated to 100°C at a rate of 10°C / min in a nitrogen atmosphere and then isothermally maintained for 1 hour to remove moisture. Thereafter, the temperature may be measured by heating to 600°C at a rate of 10°C / min and then measuring the temperature at which a 5% weight loss occurs.

[0055] The available polyimide solution of the present invention has the characteristics of excellent solubility in organic solvents while maintaining excellent optical, mechanical, and thermal properties.

[0056] In another aspect, a polyimide film manufactured from the available polyimide solution of the present invention is provided.

[0057] In another aspect, the present invention provides a polyimide hollow fiber membrane manufactured from the available polyimide solution of the present invention.

[0058] The thickness of the polyimide film or the polyimide hollow fiber membrane may be appropriately selected in consideration of the intended use, usage environment, physical properties, etc. For example, the thickness of the polyimide film or the polyimide hollow fiber membrane may be 1 to 100 μm, 5 to 50 μm, 10 to 40 μm, or 15 to 25 μm, but is not limited thereto.

[0059] In another aspect, the present invention provides a polyimide powder prepared from the available polyimide solution of the present invention.

[0060] In another aspect, a part comprising a molded body formed from the available polyimide solution of the present invention is provided.

[0061] Specifically, the above components may be, but are not limited to, electronic circuit board components, semiconductor devices, display substrates, membranes, lithium ion battery components, solar cell components, fuel cell components, motor windings, engine peripheral components, paints, optical components, heat dissipation materials, electromagnetic shielding materials, surge components, dental materials, slide coatings, and electrostatic chucks.

[0062] The polyamic acid composition for preparing a polyimide solution according to the present invention and the soluble polyimide solution prepared therefrom have soluble properties in organic solvents, and can be prepared into various products such as films and fibers simply by drying the solvent without an imidization process at high temperatures, thereby improving the ease of the process.

[0063] In addition, the polyamic acid composition for preparing a polyimide solution according to the present invention and the soluble polyimide solution prepared therefrom exhibit excellent solubility properties in organic solvents and have excellent optical, mechanical, and thermal properties.

[0064] In addition, the polyamic acid composition for preparing a polyimide solution according to the present invention and the soluble polyimide solution prepared therefrom have the effect of being provided in various forms such as varnish, film, and powder according to the intended use.

[0065] In addition, the polyamic acid composition for preparing a polyimide solution according to the present invention and the soluble polyimide solution prepared therefrom have the effect of being applicable to various fields such as display substrates, insulating coatings, fibers, and membranes.

[0066] Figure 1 shows an appearance photograph of a polyimide film manufactured according to Examples 2-3, 2-4, and Comparative Examples 2-5 and 2-6.

[0067] To aid in understanding the present invention, examples are presented. The following examples are provided solely to facilitate a better understanding of the present invention, and the scope of the present invention is not limited by the examples.

[0068] <Example 1: Preparation of polyimide solution>

[0069] Example 1-1

[0070] 100 mol% of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was dissolved in dimethylpropanamide (DMPA) organic solvent in a nitrogen / room temperature atmosphere. Subsequently, 95 mol% of bisphenol A dianhydride (BPADA) and 5 mol% of biphenyl tetracarboxylic dianhydride (BPDA) were added and randomly polymerized for 4 hours to obtain polyamic acid (step S1).

[0071] 1.0 molar equivalent of carbonyl diimidazole (CDI) was added as an additive to the polyamic acid obtained above, and a chemical imidization process was performed in a continuous polymerization batch process at 40°C for 2.5 hours to prepare a polyimide solution containing polyimide (solid content 15 wt%) (step S2).

[0072] The above polyimide solution additionally contains an imidazole compound, which is a by-product of the above carbonyl diimidazole, and can be used in the form of a varnish without purification, filtration, and drying processes.

[0073] Examples 1-2 to 1-5, Comparative Examples 1-1 to 1-7

[0074] A polyimide solution was prepared in the same manner as in Example 1-1, except that the monomer components and content ratios were adjusted as shown in Table 1 below.

[0075]

[0076] The monomer types and contents, additive types and contents, and solubility of the examples and comparative examples are described in Table 1 below. To evaluate solubility, the presence of floating matter in the polyimide solutions prepared according to the examples and comparative examples was visually confirmed. If no floating matter was present in the solution, the solvent solubility was recorded as O, and if floating matter was present in the solution, the solvent solubility was recorded as X.

[0077] Distinction Anhydride Monomer (mol%) Diamine Monomer (mol%) Additive (mol%) Solvent Solubility BPADABPDAPMDAFFDATFMB4,4'-ODACDIExample 1-1955--100-1.00Example 1-29010--100-1.00Example 1-38515--100-1.00Example 1-48020--100-1.00Example 1-58020-5050-1.00Comparative Example 1-1--100-100-1.0XComparative Example 1-290-10-100-1.00Comparative Example 1-380-20-100-1.00Comparative Example 1-470-30--1001.0XComparative Example 1-550-50--1001.0X Comparison Example 1-630-70--1001.0X Comparison Example 1-7-60401090-1.0X

[0078] The abbreviations for the substances used in Table 1 above are as follows.

[0079] BPADA: Bisphenol A dianhydride

[0080] BPDA: Biphenyl tetracarboxylic dianhydride

[0081] PMDA: Pyromellitic dianhydride

[0082] FFDA: 9,9-bis(3-fluoro-4-aminophenyl)fluorene

[0083] TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0084] 4,4'-ODA: 4,4'-diaminodiphenyl ether

[0085] CDI: Carbonyl diimidazole

[0086]

[0087] As shown in Table 1 above, it was confirmed that the polyimide solutions of Examples 1-1 to 1-5 according to the present invention exhibited solubility properties in organic solvents.

[0088] However, it was confirmed that the polyimide solutions of Comparative Examples 1-1, 1-4 to 1-7 were insoluble in a gel state.

[0089]

[0090] <Example 2: Preparation of polyimide film>

[0091] Examples 2-1 to 2-5

[0092] The soluble polyimide solutions prepared according to Examples 1-1 to 1-5 were coated onto a glass substrate using a spin coater (MSB200, Mikasa) to a thickness of 20 μm and dried at 200°C for 30 minutes. The coating method is not particularly limited. After cooling to 25°C, the solution was separated from the glass substrate to produce a polyimide film with a thickness of approximately 20 μm.

[0093] At this time, the imidazole remaining in the polyimide solution is removed by heat during the drying process and does not remain in the final polyimide film.

[0094] Comparative Examples 2-1, 2-4 to 2-7

[0095] According to Table 1 above, the polyimide solutions of Comparative Examples 1-1, 1-4 to 1-7 were insoluble and produced as polyimide films using a method different from that of the polyimide films of Examples 2-1 to 2-5.

[0096] Specifically, Comparative Examples 1-1, 1-4 to 1-7 were prepared by using the monomers in Table 1 above, but performing step S1 in the manufacturing method of Example 1. Polyamic acid was coated on a glass substrate using a spin coater (MSB200, Mikasa) to a thickness of 20 μm and dried at 450°C for 60 minutes (thermal imidization). The coating method is not particularly limited. Subsequently, the film was cooled to 25°C and separated from the glass substrate to prepare a polyimide film having a thickness of approximately 20 μm.

[0097] Comparative Examples 2-2 and 2-3

[0098] According to Table 1 above, it can be confirmed that the polyimide solutions of Comparative Examples 1-2 and 1-3 are soluble. Therefore, a polyimide film was manufactured in the same manner as the polyimide film of Examples 2-1 to 2-5, except that the polyimide solutions of Comparative Examples 1-2 and 1-3 were used instead of the polyimide solutions of Examples 1-1 to 1-5.

[0099]

[0100] <Experimental Example: Evaluation of the Characteristics of Polyimide Solution>

[0101] The optical, mechanical, and thermal properties were evaluated using the polyimide films manufactured in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 above.

[0102] Experimental Example 1: Optical Characteristics Evaluation

[0103] Figure 1 shows an appearance photograph of a polyimide film manufactured according to Examples 2-3, 2-4, and Comparative Examples 2-5 and 2-6.

[0104] In addition, the light transmittance of the polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 was measured at 440 to 740 nm using an ultraviolet / visible spectrophotometer (UV-Vis Spectrophotometer), and the average value was calculated. Specifically, the measurement of the light transmittance at 440 to 740 nm refers to measuring the light transmittance at all wavelengths from 440 to 740 nm. The measurement results are shown in Table 2 below.

[0105] In addition, the yellow index (YI) and imidization ratio of the polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 were measured. The yellow index was measured using a Hunter Lab Color-meter. The measurement results are shown in Table 2 below.

[0106]

[0107] Experimental Example 2: Mechanical Properties Evaluation

[0108] (1) Modulus (Young's modulus)

[0109] The polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 were prepared as samples of 400 mm in length and 10 mm in width using an Instron 5564 UTM device from INSTRON, and the modulus was measured at a speed (20 mm / min), and the average of 10 samples was calculated. The results are shown in Table 2 below.

[0110] (2) Tensile strength

[0111] The polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7, which were manufactured in the form of films measuring 400 mm in length and 10 mm in width, were subjected to tensile strength measurements at a speed (20 mm / min) using an Instron 5564 UTM device manufactured by INSTRON, and the average of 10 samples was calculated. The results are shown in Table 2 below.

[0112] (3) Elongation

[0113] The elongation of polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 was measured under room temperature conditions using an Instron 5564 UTM device from INSTRON according to the ASTM D882 method. The results are shown in Table 2 below.

[0114]

[0115] Experimental Example 3: Thermal Characteristics Evaluation

[0116] (1) Glass transition temperature (Tg)

[0117] The point at which the polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 rapidly expanded was measured as the on-set point using DMA at 5°C / min. The results are shown in Table 2.

[0118]

[0119] (2) Thermal decomposition temperature of 5 wt% (Td 5 wt%)

[0120] A TA thermogravimetric analysis Q50 model was used, and the polyimide films manufactured according to Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 were heated to 100°C at a rate of 10°C / min under a nitrogen atmosphere and then maintained isothermally for 1 hour to remove moisture. Thereafter, the temperature was increased to 600°C at a rate of 10°C / min, and the temperature at which a 5% weight loss occurred was measured, and the results are shown in Table 2 below.

[0121] ClassificationOptical propertiesMechanical propertiesThermal propertiesLight transmittance440-740nm (%)YIModulus (GPa)Tensile strength (MPa)Elongation (%)Tg (℃)Td 5wt% (℃)Example 2-1891.372.951067.71234512Example 2-2891.373.151128.42240513Example 2-3891.223.021189.42243520Example 2-4861.413.111924.3243536Example 2-5891.163.2212021.2232516Comparative example 2-18212.15.823.8199251533Comparative example 2-2891.717.116.22105239522Comparative Example 2-3891.976.005.71100241527Comparative Example 2-4894.164.167.36109243529Comparative Example 2-5885.85.87.01121243531Comparative Example 2-6887.497.492.38118245530Comparative Example 2-784138.0015.02231302530

[0122] According to Table 2, it was confirmed that the polyimide film manufactured using the available polyimide solution according to the embodiment of the present invention had excellent optical properties compared to the polyimide film of the comparative example, with an excellent light transmittance of about 86% or more at a wavelength of 440 to 740 nm and a low yellowness of 1.50 or less.

[0123] In addition, it was confirmed that the polyimide film manufactured from the available polyimide solution of the present invention has excellent mechanical properties, such as a modulus of 2.8 to 30.0 GPa, a tensile strength of 100 MPa or more, and an elongation of 30% or less.

[0124] In addition, it was confirmed that the polyimide film manufactured from the available polyimide solution of the present invention has excellent thermal properties, having a glass transition temperature of 232°C or higher and a 5 wt% thermal decomposition temperature of 512°C or higher.

[0125] In summary, it was confirmed that the polyimide film manufactured from the available polyimide solution of the present invention has excellent optical, mechanical, and thermal properties suitable for use as a display substrate.

[0126]

[0127] The specification omits detailed descriptions of matters that would be readily apparent and inferred by those skilled in the art. Furthermore, various modifications, other than the specific examples described herein, are possible without altering the technical spirit or essential configuration of the invention. Therefore, the present invention may be practiced in ways other than those specifically described and exemplified herein, as will be apparent to those skilled in the art.

Claims

1. Contains a polyamic acid containing an dianhydride monomer and a diamine monomer as polymerization units, The above dianhydride monomers include bisphenol A dianhydride (BPADA) and biphenyl tetracarboxylic dianhydride (BPDA), A polyamic acid composition for preparing an available polyimide solution, wherein the above diamine monomer comprises 2,2'-bis(trifluoromethyl)benzidine (TFMB).

2. In paragraph 1, A polyamic acid composition for preparing an available polyimide solution, wherein the polyamic acid composition for preparing an available polyimide solution further comprises carbonyl diimidazole.

3. In paragraph 2, A polyamic acid composition for preparing an available polyimide solution, wherein the polyamic acid composition for preparing an available polyimide solution comprises 0.5 to 1.5 mol% of the carbonyl diimidazole with respect to 1 molar equivalent of the polyamic acid.

4. In paragraph 1, A polyamic acid composition for preparing a soluble polyimide solution, wherein the content of bisphenol A dianhydride (BPADA) among the total dianhydride monomers is 60 mol% or more and less than 100 mol%.

5. In paragraph 1, A polyamic acid composition for preparing a soluble polyimide solution, wherein the content of biphenyl tetracarboxylic dianhydride (BPDA) among the total dianhydride monomers is greater than 0 mol% and less than or equal to 40 mol%.

6. In paragraph 1, The above diamine monomer further comprises at least one selected from the group consisting of 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6-FAP), 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), methylenedianiline (MDA), 4-[2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl]aniline (HFDA), 2-amino-4-(3-amino-4-hydroxyphenyl)sulfonylphenol and bis[4-(3-aminophenoxy)phenyl]sulfone (m-BAPS). Polyamic acid composition for preparing polyimide solution.

7. A polyimide comprising an dianhydride monomer and a diamine monomer as polymerization units, The above dianhydride monomers include bisphenol A dianhydride (BPADA) and biphenyl tetracarboxylic dianhydride (BPDA), A soluble polyimide solution wherein the above diamine monomer comprises 2,2'-bis(trifluoromethyl)benzidine (TFMB).

8. In paragraph 7, The above-mentioned soluble polyimide solution is in the form of a varnish.

9. In paragraph 7, A soluble polyimide solution, wherein the above soluble polyimide solution further comprises an imidazole compound.

10. In paragraph 7, The above polyimide is a soluble polyimide solution that exhibits solubility properties in organic solvents for a solid content of 30 wt% or less.

11. In paragraph 10, A soluble polyimide solution, wherein the organic solvent comprises at least one selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), N,N'-dimethylpropionamide (DMPA), and N,N-diethylacetamide (DEAc).

12. In paragraph 7, A soluble polyimide solution, wherein the content of bisphenol A dianhydride (BPADA) among the total dianhydride monomers is 60 mol% or more and less than 100 mol%.

13. In paragraph 7, A soluble polyimide solution, wherein the content of biphenyl tetracarboxylic dianhydride (BPDA) among the total dianhydride monomers is greater than 0 mol% and less than or equal to 40 mol%.

14. In paragraph 7, The above diamine monomer further comprises at least one selected from the group consisting of 9,9-bis(3-fluoro-4-aminophenyl)fluorene (FFDA), 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6-FAP), 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), methylenedianiline (MDA), 4-[2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl]aniline (HFDA), 2-amino-4-(3-amino-4-hydroxyphenyl)sulfonylphenol and bis[4-(3-aminophenoxy)phenyl]sulfone (m-BAPS). Polyimide solution.

15. Polyimide manufactured from the available polyimide solution of Article 7.

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