Novel acid dianhydride and method for producing the same, and polyamic acid and polyimide using the same

Abstract

Provided is a novel acid dianhydride and a method for producing the same, and a polyamic acid and a polyimide using the same, the novel acid dianhydride being used as a raw material monomer for a polyimide that is excellent in heat resistance, low thermal expansion, and mechanical strength while using a bio-based raw material. An acid dianhydride represented by the following Chemical Formula 1. [Chemical Formula 1]

Description

Technical Field

[0001] This invention relates to novel acid dianhydrides, methods for their manufacture, and polyamic acids and polyimides manufactured using these novel acid dianhydrides. Background Technology

[0002] In recent years, with the miniaturization, weight reduction, and space-saving development of electronic devices, the demand for thin, lightweight, flexible, and highly durable flexible printed circuit boards (FPCs) that withstand repeated bending has increased. Because FPCs can achieve three-dimensional and high-density installation even in limited spaces, their applications are gradually expanding to wiring, cables, connectors, and other components in movable parts of electronic devices such as HDDs, DVDs, and smartphones. FPCs are mostly manufactured by forming circuits on the metal layers of a metal-clad laminate, which is formed by laminating a metal layer (using metal foil, etc.) with an insulating resin substrate (insulating resin layer).

[0003] Polyimide films possess excellent properties in terms of heat resistance, cold resistance, chemical resistance, electrical insulation, and mechanical strength, and are therefore widely used in various fields. In particular, they are widely used as insulating resin layers in FPCs due to their excellent heat resistance and high rigidity. Especially, electronic devices are expected to become increasingly more functional and miniaturized in the future. Therefore, for example, in FPCs, the demand for multilayer applications is expected to increase. Furthermore, corresponding to the thinning of casings in electronic devices such as mobile phones and smartphones, there is a growing trend towards thinner circuit boards themselves. Therefore, with the thinning of the insulating resin layer accompanying the thinning of the circuit board itself, the polyimide film used for the insulating resin layer requires higher mechanical strength, i.e., a higher elastic modulus, in order to suppress wrinkles during pattern processing and handling. In addition, when the coefficient of thermal expansion of the polyimide film is not close to that of the metal foil, curling occurs during heat processing due to the difference in coefficients of thermal expansion; therefore, controlling the coefficient of thermal expansion becomes important.

[0004] Furthermore, polyimide is manufactured using tetracarboxylic dianhydride and diamine compounds as raw material monomers. Such raw materials are mostly derived from petrochemicals. On the other hand, against the backdrop of global warming and the depletion of oil resources, the demand for environmentally friendly materials using bio-based raw materials such as plants is surging worldwide. Using bio-based raw materials can significantly contribute to carbon neutrality by reducing the use of fossil resources such as oil, and also contribute to the advancement of a circular economy and the formation of a sustainable society. Consequently, the demand for sustainable product development is also increasing.

[0005] In light of this background related to polyimides and the demands of recent years, Patent Document 1 proposes a polyimide material that enhances its bio-based composition and exhibits excellent heat resistance, optical properties, and dielectric properties by using tetracarboxylic dianhydrides synthesized from dihydrohexyl alcohols such as isosorbide and isomannitol, which are cellulose derivatives used as bio-based raw materials, and trimellitic anhydrides. However, regarding the polyimide described in Patent Document 1, the cellulose-derived portions such as isosorbide are alicyclic, resulting in low molecular chain interaction and planarity. Therefore, there is room for further improvement in the aforementioned properties such as heat resistance, mechanical strength, and coefficient of thermal expansion.

[0006] Furthermore, in Non-Patent Literature 1, an ether dianhydride and diamine monomer derived from aromatic plants, daidzein, were studied. However, in polyimides polymerized with 4,4'-oxodiphenylamine, a common diamine monomer and the ether dianhydride, the glass transition temperature was as low as 302°C, indicating room for improvement in heat resistance. This is presumably because the aforementioned ether dianhydride possesses ether bonds that function as flexible groups in polyimides, resulting in easy molecular movement and poor planarity. Moreover, since the dianhydride monomer is synthesized from 4-chlorophthalic anhydride and daidzein via a base etherification reaction, the anhydride reacts with the base. Therefore, to produce the anhydride, acids such as acetic anhydride and glacial acetic acid are required, making the manufacturing process complex and environmentally burdensome.

[0007] Existing technical documents Patent documents Patent Document 1: International Publication No. 2023 / 027031 Non-patent literature Non-patent literature 1: ACS Sustainable Chem. Eng. 2023,11,4789-4799. Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The purpose of this invention is to provide a novel acid dianhydride and its manufacturing method, as well as polyamic acid and polyimide using the same, wherein the novel acid dianhydride is used as a raw material monomer for polyimide with excellent heat resistance, low thermal expansion and mechanical strength while using bio-based raw materials.

[0010] means for solving problems

[0011] In order to achieve the above objectives, the inventors conducted in-depth research and came up with the idea that, focusing on daidzein as an aromatic bio-based raw material with high planarity, the planarity is further increased by introducing ester bonds, and the interaction between molecular chains is easily manifested, thereby creating a structure with excellent heat resistance, low thermal expansion and mechanical strength, thus providing the acid dianhydride shown in the following chemical formula 1.

[0012] That is, the present invention is an acid dianhydride represented by the following chemical formula 1.

[0013] <Chemical Formula 1> [Chemical Formula 1]

[0014] Here, the preferred biomass content of the acid dianhydride is 10% or higher.

[0015] In addition, the present invention is a polyamic acid, characterized in that it contains an anhydride residue derived from an anhydride component and a diamine residue derived from a diamine component, wherein the above-mentioned dianhydride is used as the anhydride component; the present invention is a polyimide formed by imidizing the polyamic acid.

[0016] Here, the polyimide is preferably used as a material for electronic substrates.

[0017] Furthermore, the present invention provides a method for manufacturing acid dianhydride, characterized in that, in the method of manufacturing the acid dianhydride, an aprotic polar solvent is used as the reaction solvent in the manufacturing method of esterifying daidzein or its derivative with trimellitic anhydride halide or trimellitic anhydride using a reaction solvent.

[0018] Here, the aforementioned aprotic polar solvent preferably includes one or more solvents selected from the group consisting of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone.

[0019] In addition, in this manufacturing method, it is preferable to include a cleaning step using a solvent to clean the product after the esterification reaction and / or a purification step to purify the product. The reaction solvent for the esterification reaction includes dimethylformamide and / or dimethylacetamide, and the solvent for the cleaning step and / or purification step is a nitrile solvent.

[0020] Invention Effects

[0021] According to the present invention, an acid dianhydride using bio-based raw materials and possessing a structure exhibiting excellent heat resistance, low thermal expansion, and mechanical strength can be provided. Furthermore, polyamic acid and polyimide using such an acid dianhydride can be provided. Moreover, a method for manufacturing the aforementioned acid dianhydride can be provided. That is, a novel acid dianhydride can be provided as a raw material monomer for manufacturing the polyimide, etc. Furthermore, it can contribute to the development of carbon-neutral, circular economy, and sustainable products.

[0022] Furthermore, the polyimide using the acid dianhydride of the present invention exhibits excellent heat resistance and other properties while utilizing bio-based raw materials. Therefore, it is not limited to FPCs and can be used as a material for electronic substrates. In addition to insulating materials used in electronic devices such as semiconductors, and plastic substrates used in liquid crystal displays (LCDs), organic electroluminescent (EL) displays, electronic paper, light-emitting diode (LED) devices, and solar cells, it is also expected to be used in transportation machinery materials such as automobiles. Moreover, from the viewpoint of using bio-based raw materials, the acid dianhydride of the present invention is not limited to monomers for polyimides, but can also be applied to polyamide monomers, polyester modifiers, epoxy resin curing agents, etc. Attached Figure Description

[0023] Figure 1 Representing Example 1 1 ¹H-NMR measurement results. Detailed Implementation

[0024] The embodiments of the present invention will be described below.

[0025] <The acid dianhydride of the present invention>

[0026] The acid dianhydride of the present invention has the structure represented by the above <Chemical Formula 1>.

[0027] The acid dianhydride of the present invention was novelly achieved by focusing on daidzein, an aromatic bio-based raw material with high planarity. Furthermore, by using daidzein and introducing it via ester bonds, the planarity is further increased, and the interaction between molecular chains is easily manifested, resulting in a structure with excellent heat resistance, low thermal expansion, and mechanical strength.

[0028] The novel acid dianhydride of this invention exhibits excellent heat resistance, and therefore, as a heat-resistant property, a high melting point and a high thermal decomposition temperature are preferred. Furthermore, from the viewpoint of these properties, this acid dianhydride is preferably used for the aforementioned applications. It is particularly preferred for use in the manufacture of polyamic acid as a precursor to polyimide or similar products.

[0029] The acid dianhydride of the present invention is synthesized using daidzein as a bio-based raw material. Therefore, it is preferable to have a high degree of bio-based ...

[0030] In this invention, biomass index is based on the following definition. That is, the biomass index can be determined based on naturally occurring radiocarbon dating as measured by standard ASTM D 6866. 14The bio-based carbon content is determined by the concentration of C). Furthermore, in addition to measuring the bio-based carbon content in this way, calculations can also be performed based on the proportion of carbon mass in the bio-based raw materials used. Radioactive carbon derived solely from bio-based raw materials is 100%, while that derived solely from petroleum is 0%. When the bio-based content of reactants, compositions, etc., is confirmed at the raw material stage, it can be easily calculated based on the proportion of raw materials present in the reactants or compositions.

[0031] <Methods for manufacturing acid dianhydrides>

[0032] <Reaction Process>

[0033] There are no particular limitations on the synthesis methods of the compounds represented by the above <Chemical Formula 1>. For example, as shown in the following reaction formula 1, an esterification reaction in which daidzein and trimellitic anhydride halides are reacted in the presence of a basic compound and a reaction solvent can be cited.

[0034] [Reaction Formula 1] [Chemical Formula 2] (In the above reaction formula, X represents a halogen atom.)

[0035] In addition to esterification reactions using trimellitic anhydride halides, other methods include direct dehydration of trimellitic anhydride and daidzein at high temperatures, or transesterification reactions of daidzein diacetate derivatives with trimellitic anhydride at high temperatures using acid catalysts, condensing agents such as N,N'-dicyclohexylcarbodiimide, etc. From the viewpoint of economy and yield, the method using trimellitic anhydride halides is preferred.

[0036] Examples of trimellitic anhydride halides include trimellitic anhydride fluoride, trimellitic anhydride chloride, trimellitic anhydride bromide, and trimellitic anhydride iodide. From the viewpoint of ease of purification and availability, trimellitic anhydride chloride is preferred. The feed ratio of trimellitic anhydride halide is not particularly limited as long as it is 2 moles or more relative to 1 mole of daidzein; generally, 2 to 6 moles is preferred, more preferably 2 to 4 moles, and even more preferably 2 to 3 moles. When it is less than 2 moles, the introduction of the anhydride group into daidzein becomes insufficient, and it is prone to becoming a monomer with less than one function. Therefore, for example, in polymerization reactions using this dianhydride, there is a risk of hindering the increase of molecular weight. On the other hand, if the feed amount of trimellitic anhydride halide is excessive, a large amount of solvent must be used in purification to remove unreacted trimellitic anhydride halide, which is economically disadvantageous. Therefore, it is preferable to set it to the aforementioned upper limit or below.

[0037] Hydrogen halides are generated by the reaction of daidzein with trimellitic anhydride halides, therefore a basic compound is added to the reaction system. There are no particular restrictions on the basic compound, but tertiary amine organic compounds such as pyridine and triethylamine are preferred. Pyridine is more preferred from the perspectives of purification and cost. The amount of basic compound added is not particularly limited as long as it is 2 moles or more relative to the amount of hydrogen halides generated, i.e., daidzein, and is typically preferred to be 2 to 6 moles, more preferably 2 to 4 moles, and even more preferably 2 to 3 moles. When the amount is less than 2 moles, the generated hydrogen halides cannot be completely captured, resulting in side reactions. On the other hand, if the amount of basic compound added is excessive, a large amount of solvent is needed for purification to remove unreacted basic compounds, which is economically disadvantageous; therefore, it is preferable to set it below the aforementioned upper limit.

[0038] As a reaction solvent, there are no particular restrictions as long as it is inactive in the above reaction and has substrate solubility. For example, ketone solvents such as acetone and methyl ethyl ketone, ether solvents such as tetrahydrofuran and dioxane, aromatic solvents such as benzene, toluene, and xylene, ester solvents such as ethyl acetate and butyl acetate, nitrile solvents such as acetonitrile, lactone solvents such as γ-butyrolactone, sulfone solvents such as dimethyl sulfoxide, halogen solvents such as chloroform and dichloromethane, and amide solvents such as dimethylformamide and dimethylacetamide are all nonprotic polar solvents. These reaction solvents can be used individually or in combination to adjust solubility. Since daidzein has low solubility in organic solvents, it is preferable to use γ-butyrolactone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide, which have high solubility, are versatile, and have low harmfulness. It is even more preferable to use dimethylformamide and dimethylacetamide, which have even higher solubility.

[0039] The amount of solvent used is not particularly limited as long as it is sufficient to maintain the substrate's dissolution, allow the reaction to proceed, and provide sufficient flowability for stirring as the product precipitates. For example, the amount is preferably 5 to 50 times the weight of daidzein, more preferably 10 to 30 times the weight, and even more preferably 10 to 20 times the weight. At less than 5 times the weight, there is a risk of reduced flowability when the product precipitates, making the reaction difficult and stirring challenging. At more than 50 times the weight, there is a risk that the product may also dissolve in the solvent, resulting in a lower yield.

[0040] The reaction temperature is not particularly limited, but a range of -20°C to +50°C is preferred, and a range of -10°C to +30°C is more preferred. If the reaction temperature is too high, the yield may decrease due to side reactions, product hydrolysis, etc. Conversely, if the reaction temperature is too low, the reaction rate may slow down, and the solubility of the substrate may decrease. The reaction time is not particularly limited, but 6 to 36 hours is preferred, and 12 to 24 hours is more preferred. A short reaction time may prevent the reaction from proceeding, while a long reaction time may lead to a deterioration in productivity.

[0041] From the perspective of reducing environmental impact, daidzein is preferably derived from bio-based sources. Daidzein is abundant in legumes such as soybeans and kudzu, and can be obtained through isolation and purification from these seeds, roots, leaves, and stems. From the perspective of dietary requirements, it is preferable to use substances derived from sources other than soybean seeds, and even more preferably, daidzein derived from kudzu.

[0042] There are no particular limitations on the method for recovering the target compound, but it is preferable to modify it appropriately depending on the reaction solvent. For example, when using a halogen-based solvent, the target compound dissolves in the solvent, while the salt of hydrogen halide and basic compound precipitates. Therefore, methods such as filtering to separate the salt, adding the filtrate dropwise to a poor solvent to precipitate the target compound, or removing the solvent from the filtrate by distillation such as vacuum distillation can be used. Furthermore, when using nitrile solvents such as acetonitrile or amide solvents such as dimethylacetamide, the target compound precipitates, while the salt of hydrogen halide and basic compound dissolves in the solvent. Therefore, methods such as recovering the target compound by filtering can be used. Additionally, when using ether solvents such as tetrahydrofuran, both the target compound and the salt of hydrogen halide and basic compound precipitate. Therefore, methods such as applying a large amount of pure water to the filtrate to dissolve and remove the salt of hydrogen halide and basic compound can be used. In this invention, since amide solvents with high solubility for daidzein are preferred, filtering to separate the precipitated target compound is preferred as the recovery method in this case.

[0043] When using amide solvents such as dimethylacetamide as the reaction solvent, after the above-mentioned filtration and recovery, the amide solvent tends to remain in the target compound. When the residual amount of amide solvent is high, it sometimes turns yellow during drying and during the dehydration and ring-closure process based on dicarboxylic acid described later. Furthermore, amide solvents have high surface tension and significantly poor filterability. Therefore, after the reaction, it is preferable to add a non-protic polar solvent with low surface tension to the reaction solvent to reduce the residual amount of amide solvent and improve filterability. As this non-protic polar solvent, from the viewpoint that the target compound is difficult to dissolve, has a high affinity for amide solvents, and is preferably a solvent that dissolves in the salts of hydrogen halides and basic compounds, nitrile solvents such as acetonitrile are preferred. As a nitrile solvent, acetonitrile, propionitrile, and butyronitrile are preferred, and acetonitrile is more preferred. The amount of solvent added is preferably 0.5 to 3 times by weight relative to the amide reaction solvent, and more preferably 0.75 to 2 times by weight. When the amount of solvent is low, the amide solvent tends to remain, and the filterability is not improved. Excessive solvent volume leads to increased filtration volume, which is detrimental to productivity. Increased solvent consumption also negatively impacts economic efficiency.

[0044] <Cleaning Process>

[0045] To reduce the residual amount of amide solvent after filtration and recovery, it is preferable to clean the target compound using an aprotic polar solvent after filtration and recovery. For the same reasons mentioned above, nitrile solvents such as acetonitrile are preferred as the cleaning solvent. The amount of cleaning solvent is preferably 0.5 to 3 times by weight relative to the reaction solvent, more preferably 0.75 to 2 times by weight. Too little cleaning solvent leads to amide solvent residue, while too much solvent results in a large filtration volume, which is detrimental to productivity and increases solvent consumption, thus being economically unfavorable.

[0046] <Drying Process>

[0047] After washing, the target compound recovered by filtration is preferably dried to reduce the residual amount of amide solvent. The preferred drying temperature is 50–120°C, more preferably 80–100°C. At higher drying temperatures, the amide solvent decomposes, sometimes resulting in a yellow color. Conversely, at lower drying temperatures, the amount of amide solvent removed is less. The preferred drying time is 2–24 hours, more preferably 5–12 hours. Longer drying times are disadvantageous in terms of productivity and economy, while shorter drying times result in less amide solvent removal. The drying pressure is not particularly limited under normal or reduced pressure, but drying under reduced pressure of around 1–10 kPa is preferred as it removes the solvent more effectively.

[0048] <Purification Process>

[0049] After drying, the target compound is preferably purified to reduce the residual amount of amide solvent and other impurities. The purification method is not particularly limited; examples include recrystallization and resizing, where the target compound is suspended in a solvent and crystallized. In recrystallization, the target compound is dissolved in a solvent while being heated, followed by cooling to allow crystals to precipitate. However, in resizing, it is not necessary to completely dissolve the target compound. Given the relatively low solubility of the dianhydride in organic solvents, resizing is more preferred. The solvent used in resizing is not particularly limited, but nitrile solvents such as acetonitrile, which have a high affinity for amide solvents, are preferred. The amount of solvent is preferably 5 to 20 times the weight of the target compound, more preferably 7 to 10 times the weight. Insufficient solvent leads to inadequate purification, while excessive solvent leads to over-dissolution of the target compound and a reduced yield. In resizing, the solvent and target compound need to be heated, preferably at a temperature in the range of 40 to 100°C, more preferably in the range of 60 to 85°C. At low temperatures, crystallization becomes insufficient; at excessively high temperatures, the target compound is prone to hydrolysis.

[0050] <Dehydration Process>

[0051] After purification, the target compound recovered by filtration is readily converted to dicarboxylic acids due to partial ring-opening via hydrolysis of the dianhydride. Therefore, it is preferable to prepare the dianhydride via a dehydration reaction. There are no particular limitations on the dehydration reaction method; examples include dehydration using acetic anhydride and dehydration by heating while maintaining the solid state. When using acetic anhydride, since acid-resistant equipment is required and impurities such as acetates are easily generated, a dehydration method by heating is preferred. During heating dehydration, the heating temperature is preferably in the range of 120–170°C, more preferably in the range of 150–160°C. At lower temperatures, the dehydration reaction proceeds slowly; at higher temperatures, the yield decreases due to sublimation, and decomposition is more likely to occur. Furthermore, there are no particular limitations on the heating pressure, whether under normal or reduced pressure. Dehydration is more efficient when carried out under reduced pressure of approximately 1–10 kPa, and is therefore preferred. The heating time is preferably 2–24 hours, more preferably 6–12 hours. A short heating time will not allow the dehydration reaction to proceed completely, while a long heating time will reduce productivity.

[0052] Furthermore, the order of washing → drying → purification → dehydration after filtration following the above reaction is not limited to this. It can be modified from the viewpoint of reducing the residue of the amide solvent and the resulting reduction in coloration and impurities. For example, the order can be washing → drying → dehydration → purification. Additionally, washing and purification can be performed multiple times.

[0053] <The polyamic acid and polyimide of the present invention>

[0054] Furthermore, from another perspective, the present invention relates to a polyamic acid, characterized in that it contains an anhydride residue derived from an anhydride component and a diamine residue derived from a diamine component, wherein the aforementioned acid dianhydride is used as the anhydride component. The polyamic acid is a precursor to a polyimide, configured to have the aforementioned anhydride residue and the aforementioned diamine residue, and is composed of a polymer of the repeating unit, whereby the linkage of these constituent components is considered a repeating unit. Additionally, the present invention relates to a polyimide obtained by dehydrating and ring-closing the polyamic acid through imidization. That is, the present invention relates to a polyamic acid obtained by reacting an acid dianhydride represented by <Chemical Formula 1> with a diamine, and to a polyimide obtained by dehydrating and ring-closing the polyamic acid through imidization.

[0055] The diamine is not particularly limited and can be any of the diamines used in the conventional synthesis of polyimides. Specifically, examples include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 1,3-bis(4,4'-aminophenoxy)benzene, 4,4'-diamino-1,5-phenoxypentane, 4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2'-diaminodiphenylpropane, bis(3,5-diethyl-4-aminophenyl)methane, diaminodiphenyl sulfone, diaminobenzophenone, 4,4'- Aromatic diamines include diaminobenzoylaniline, diaminonaphthalene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 4-aminophenyl-4-aminobenzoate, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)diphenyl sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 2,2'-trifluoromethyl-4,4'-diaminobiphenyl; alicyclic diamines include 1,4-diaminocyclohexane, 1,4-cyclohexanebis(methylamine), and 4,4'-diaminodicyclohexylmethane; and aliphatic diamines include tetramethylenediamine and hexamethylenediamine. Furthermore, these diamines can be used alone or in combination of two or more.

[0056] Furthermore, in the polyamic acid and polyimide of the present invention, as long as the dianhydride represented by the <Chemical Formula 1> is used as the dianhydride component, other dianhydride components may also be used in combination, provided that the purpose of the present invention is not impaired. There are no particular limitations on such other dianhydride components; various dianhydrides used in the conventional synthesis of polyimides may be used. One other dianhydride component may be used alone, or two or more may be used in combination. The amount of other dianhydride components (dianhydride residues) used is preferably 50 mol% or less, more preferably 25 mol% or less, and even more preferably 10 mol% or less, relative to 100 mol% of the total dianhydride components (all dianhydride residues). From the viewpoint of the above biomass, it is particularly preferred that other dianhydride components (dianhydride residues) are not used in combination (0 mol%).

[0057] The polyamic acid and polyimide of the present invention use the dianhydride (dianhydride residue) represented by the above <Chemical Formula 1> in the anhydride component (anhydride residue). Therefore, as described above, it is preferable that they have a high biomass content, preferably 10% or more, more preferably 15% or more, further preferably 20% or more, and most preferably 30% or more.

[0058] The method for obtaining polyamic acid according to the present invention is not particularly limited. It can be obtained by reacting an anhydride component containing the dianhydride represented by the above-described <Formula 1> with a diamine component and performing polymerization using a known manufacturing method. A simple method is to mix and react the anhydride component containing the dianhydride represented by <Formula 1> with the diamine component in an organic solvent. For example, it can be obtained by dissolving the anhydride component and the diamine component in an approximately equimolar amount in an organic solvent and then performing a polymerization reaction, typically at a temperature in the range of 0 to 100°C, for 30 minutes to 24 hours. During the reaction, the reactants are dissolved in the organic solvent at a concentration of 5 to 30% by weight, preferably 10 to 20% by weight, of the generated precursor.

[0059] Specific examples of the organic solvents used include m-cresol, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylcaprolactam, dimethyl sulfoxide (DMSO), tetramethylurea, pyridine, dimethyl sulfone, hexamethylphosphoramide, and γ-butyrolactone. These solvents can be used alone or in combination of two or more. Furthermore, even solvents that do not dissolve polyamic acid can be added to the above-mentioned solvents within the range where a homogeneous solution can be obtained.

[0060] Furthermore, the molecular weight (Mw) of the polyamic acid is preferably in the range of 1,000 to 100,000, more preferably 5,000 to 100,000, and even more preferably in the range of 10,000 to 90,000. When the molecular weight is low, the viscosity of the polyamic acid varnish decreases, raising concerns about a reduction in mechanical properties such as elongation. When the molecular weight is too high, the viscosity of the polyamic acid varnish increases, making it difficult to coat onto a substrate. From the viewpoint of film-forming properties, the viscosity of the polyamic acid varnish is preferably in the range of 1,000 to 100,000 cp, more preferably in the range of 5,000 to 50,000 cp.

[0061] In this invention, the method for obtaining polyimide by dehydrating and ring-closing polyamic acid through imidization is not particularly limited. Similar to the use of conventional polyamic acid, methods such as heating-based ring closure or chemical ring closure using a known dehydration and ring-closing catalyst can be employed. The heating method described above can be carried out in stages within any temperature range of 100–400°C, preferably 200–350°C.

[0062] Furthermore, as for polyimide, there are no restrictions on the methods used to obtain it as a polyimide layer or a polyimide film, and known methods can be used. For example, a method of manufacturing a resin film by [1] coating a solution of polyamic acid onto a support substrate (e.g., a metal layer) and drying it, followed by imidization (so-called casting method); [2] coating a solution of polyamic acid onto a support substrate and drying it, then peeling off a gel film of polyamic acid from the support substrate and imidizing it, etc. In addition, when it is composed of multiple polyimide layers, as a method of manufacturing it, for example, [3] repeatedly coating a solution of polyamic acid onto a support substrate and drying it, followed by imidization (so-called successive coating method); [4] simultaneously coating a multilayer structure of polyamic acid onto a support substrate by multilayer extrusion and drying it, followed by imidization (so-called multilayer extrusion method), etc.

[0063] The polyimide of the present invention thus obtained is, as previously described, obtained by using daidzein, an aromatic bio-based raw material with high planarity, and introducing an acid anhydride component with high planarity by introducing ester bonds, thus confirming excellent heat resistance, low thermal expansion and mechanical strength.

[0064] Regarding such heat resistance, the polyimide of the present invention preferably has a glass transition temperature (Tg) of 300°C or higher. More preferably, it has a glass transition temperature (Tg) of 350°C or higher, and even more preferably, it has a glass transition temperature (Tg) of 380°C or higher. In addition, in the thermal decomposition test, the 5% weight loss temperature (thermal decomposition temperature) (Td5) is preferably 400°C or higher, more preferably 420°C or higher, and even more preferably 430°C or higher.

[0065] Furthermore, regarding low thermal expansion, the coefficient of thermal expansion (CTE) of the polyimide of the present invention is preferably 50 ppm / K or less, more preferably 45 ppm / K or less, even more preferably 35 ppm / K, and particularly preferably 25 ppm / K or less. There is no limitation on the lower limit value; 1 ppm / K or more is acceptable.

[0066] Thus, the polyimide using the aforementioned acid dianhydride of the present invention exhibits excellent heat resistance and other properties even when using bio-based raw materials, and is therefore not limited to FPCs, but is particularly preferred for use as a material for electronic substrates. For example, it is suitable for use in laminates, printed circuit boards, core layers of multilayer substrates, add-ins, resin-coated copper foils, copper-clad laminates, films for TABs, and prepregs for them. These electronic substrate materials can all be manufactured using known methods.

[0067] In addition to its applications as an insulating material in electronic devices such as semiconductors, and as a plastic substrate in liquid crystal displays (LCDs), organic electroluminescent (EL) displays, electronic paper, light-emitting diode (LED) devices, and solar cells, the polyimide of the present invention is also expected to be used in transportation machinery materials such as automobiles. Furthermore, from the viewpoint of using bio-based raw materials, the dianhydride of the present invention is not limited to monomers used in polyimides, but can also be applied to polyamide monomers, polyester modifiers, epoxy resin curing agents, etc.

[0068] Example

[0069] The present invention will now be described in detail based on the embodiments, but the present invention is not limited to the scope of these embodiments.

[0070] The abbreviations used in this embodiment refer to the following compounds. Dz-TME: Acid dianhydride represented by formula 1 obtained in Example 1 PDA: p-phenylenediamine m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl 4,4'-DAPE: 4,4'-diaminodiphenyl ether DABA: 4,4'-diaminobenzoylaniline APAB: 4-Aminophenyl-4-aminobenzoate DMAc: N,N-dimethylacetamide

[0071] The analysis method used in the embodiments is as follows.

[0072] < 1 H-NMR>

[0073] The NMR spectra of the synthesized acid dianhydride were determined using a JNM-ECZ400R / S nuclear magnetic resonance apparatus (manufactured by JEOL Corporation), in which the acid dianhydride was dissolved in deuterated dimethyl sulfoxide (DMSO-d6).

[0074] Differential Thermal and Thermogravimetric Analysis (TG-DTA)

[0075] Weigh 5-7 mg of the synthesized dianhydride in an aluminum pan and measure its melting point and thermal decomposition temperature using a differential thermal calorimeter (Hitachi High-Tech Science: STA7200) under the following operating conditions.

[0076] (Operating conditions) Heating rate: 10℃ / min Measurement temperature range: 50~500℃ Measurement atmosphere: Nitrogen 200 mL / min

[0077] [Viscosity Measurement]

[0078] The viscosity of the polyamic acid solution was measured at 25°C using a cone-plate viscometer with a constant temperature water bath (manufactured by Tokimec).

[0079] [Weight-average molecular weight (Mw)]

[0080] The determination was performed using a gel permeation chromatography system (Tosoh Corporation, trade name: HLC-8220GPC). Polystyrene was used as the standard, and N,N-dimethylacetamide was used as the developing solvent.

[0081] [Tensive modulus of elasticity, tensile elongation]

[0082] Prepare a polyimide film (10mm×15mm) test piece and perform a tensile test using a TENSILON universal testing machine (ORIENTEC Corporation, RTA-250) at a tensile speed of 10mm / min according to IPC-TM-650, 2.4.19. Calculate the tensile modulus of elasticity and tensile elongation.

[0083] [Coefficient of thermal expansion (CTE)]

[0084] The polyimide film obtained by etching copper foil was cut into 3mm × 20mm sizes. Using a thermomechanical analyzer (Hitachi High-Tech Science Corporation, trade name: TMA7100), the temperature was increased from 30°C to 260°C at a rate of 10°C / min while a load of 49mN was applied. After holding at this temperature for 10 minutes, it was cooled at a rate of 10°C / min. The average coefficient of thermal expansion (CTE) from 250°C to 100°C was then calculated.

[0085] [Thermal decomposition temperature (Td5)]

[0086] The weight change of a 10-20 mg polyimide film was measured in a thermogravimetric analyzer (TG) at a certain rate from 30 °C to 550 °C under a nitrogen atmosphere. The weight at 200 °C was set to zero, and the temperature at which the weight loss rate was 5% was set as the thermal decomposition temperature (Td5).

[0087] [Glass transition temperature (Tg)]

[0088] The dynamic viscoelasticity of a resin film (10 mm × 22.6 mm) was determined using a dynamic thermomechanical analysis device when the temperature was increased from 20 °C to 400 °C at a rate of 10 °C / min. The storage modulus was set at 1.0 × 10⁻⁶. 9The inflection point at which Pa decreases sharply below the threshold is taken as the glass transition temperature.

[0089] [FCCL Curl]

[0090] A polyamic acid solution was coated onto copper foil and dried. After curing, the curling of the FCCL during cooling was observed. A case where the copper foil had a higher coefficient of thermal expansion than the polyimide and curled along the copper foil side was defined as 0; a case where the polyimide and copper foil had the same coefficient of thermal expansion and no curling was defined as ◎; a case where the polyimide had a slightly higher coefficient of thermal expansion than the copper foil and curled slightly along the polyimide side was defined as △; and a case where the polyimide had a significantly higher coefficient of thermal expansion than the copper foil and curled substantially along the polyimide side was defined as ×.

[0091] [Example 1]

[0092] <Synthesis of the dianhydride shown in chemical formula 1 (Synthesis Example 1)>

[0093] 20.2 g (96.0 mmol) of trimellitic anhydride chloride was added to a 500 ml separable flask fitted with a dropping funnel. While performing nitrogen purging, 100 g of dimethylacetamide was added, and the mixture was stirred in an ice bath until the trimellitic anhydride chloride dissolved. To a 200 ml flask, 10.2 g (40.1 mmol) of daidzein (from kudzu root), 100 g of dimethylacetamide, and 9.5 g (120.0 mmol) of pyridine were added, and the mixture was stirred until the daidzein dissolved. The solution was then transferred to a dropping funnel. While stirring the trimellitic anhydride chloride solution in an ice bath, the daidzein solution was added dropwise over 1 hour, followed by further stirring for 1 hour. Then, while performing nitrogen purging, the mixture was stirred at room temperature for 24 hours, resulting in a pale yellow slurry. 150 g of acetonitrile was added to the slurry, and after stirring for 5 minutes, the precipitate was filtered. Add 150g of acetonitrile and the above-mentioned filtrate to a 500ml separable flask, stir and wash for 10 minutes, and filter again. Dry the filtrate under vacuum at 100℃ for 6 hours to obtain 21.1g of pale yellow crude product (yield 88%). Add 21.1g of the above crude product and 150g of acetonitrile to a 500ml pear-shaped flask, heat and reflux at 85℃ for 1 hour with stirring, and then allow to return to room temperature for re-slurrying. Filter the precipitated solid, dry it under vacuum at 100℃ for 3 hours, and then dry it under vacuum at 160℃ for 10 hours to dehydrate and close the loop, obtaining 12.0g of milky white solid (yield 49.8%).

[0094] The resulting milky white solid 1 In the H-NMR measurement results, such as Figure 1 As shown, the peak observed through the following chemical shift confirms it as the dianhydride represented by <Chemical Formula 1>. The following... <1> ~ <9> Corresponding to Figure 1 The symbols in the text. σ(ppm)=7.46-7.53(2H,d, <1> ), 7.60-7.65 (1H, dd, <6> ), 7.72-7.79 (2H, d, <2> ), 7.90-7.93 (1H, s, <5> ), 8.27-8.30 (1H, s, <4> ), 8.30-8.34 (2H, t, <7> ), 8.63-8.72 (4H, m, <8> , <9> ), 8.67-8.69 (1H, s, <3> )

[0095] Furthermore, the thermogravimetric analysis (TGA) results showed a 1% thermogravimetric temperature of 266°C and a 5% thermogravimetric temperature of 406°C, based on 100°C, demonstrating high heat resistance. Additionally, a sharp endothermic peak at 290.8°C was observed in this measurement, confirming a high melting point and purity of 290.8°C. The melting point of soybean glycoside anhydride in Non-Patent Literature 1 is 229.6°C, which strongly suggests that polyimides using the dianhydride of this invention exhibit even higher heat resistance and glass transition temperature. Furthermore, the biomass of the obtained dianhydride was calculated to be 45%.

[0096] (Synthesis Examples 2~6)

[0097] To synthesize the polyamic acid solutions of Synthesis Examples 2-6, under a nitrogen stream, DMAc solvent was added to a 100 ml separable flask at the solid component concentrations shown in Table 1, along with the diamine and anhydride components (molar parts) shown in Table 1. The mixture was stirred at room temperature for 10 hours to carry out the polymerization reaction and prepare a viscous solution of polyamic acid.

[0098] The biomass degree of the obtained polyamic acid was calculated, and the results were 32-38%.

[0099] [Table 1]

[0100] Evaluation of the physical properties of polyimide films

[0101] (Examples 2-6)

[0102] Next, on copper foil (electrolytic copper foil, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., trade name: CF-T49A-DS-HD2-12, thickness: 12μm, Rz=1.2μm), each of the polyamic acid solutions A to E of Synthesis Examples 2 to 6 prepared as shown in Table 1 above was applied to achieve the cured thickness shown in Table 2. The solvent was removed by heating at 90 to 140°C. Then, the temperature was gradually increased in stages within a temperature range of 130 to 360°C to fabricate a metal-clad laminate (CCL) with an insulating resin layer composed of a polyimide layer stacked on the copper foil. To evaluate the characteristics of the polyimide layer in each metal-clad laminate, the copper foil was etched away to prepare a resin film, which was then evaluated.

[0103] The evaluation results are shown in Table 2.

[0104] [Table 2]

[0105] The homopolymer films of PDA, DABA, and APAB are brittle, making their physical properties difficult to evaluate. However, the curling of FCCL indicates that their CTE is lower than or equal to that of copper foil (below 25 ppm / K), suggesting a low coefficient of thermal expansion. Furthermore, the homopolymer films of m-TB and 4,4'-DAPE have higher CTEs than copper foil, but no decrease in storage modulus was observed up to 380°C, indicating very high heat resistance.

[0106] [Industry availability]

[0107] The novel dianhydride of this invention contains bio-based raw materials and is suitable for use in polyimides requiring high heat resistance, such as FPCs. However, it can be applied not only to polyimides but also to polyamides, polyester modifiers, epoxy resin curing agents, etc. Furthermore, it can be used as a material for electronic substrates, and is also suitable as an insulating material used in electronic devices such as semiconductors, as well as a plastic substrate used in liquid crystal displays (LCDs), organic light-emitting diode (EL) displays, electronic paper, light-emitting diode (LED) devices, solar cells, etc. In addition, it is expected to be used in materials for transportation machinery such as automobiles.

Claims

1. An acid dianhydride, represented by the following chemical formula 1: <Chemical Formula 1> [Chemical Formula 1] 。 2. The acid dianhydride according to claim 1, characterized in that, The biomass content is above 10%.

3. A polyamic acid, characterized in that, It contains anhydride residues derived from acid anhydride components and diamine residues derived from diamine components. The dianhydride described in claim 1 is used as the acid anhydride component.

4. A polyimide formed by imidizing the polyamic acid of claim 3.

5. The polyimide according to claim 4, characterized in that, It is used as a material for electronic substrates.

6. A method for manufacturing an acid dianhydride, characterized in that, This is a method for manufacturing the acid dianhydride as described in claim 1. In the manufacturing method of esterifying daidzin or its derivatives with trimellitic anhydride halides or trimellitic anhydride using a reaction solvent, an aprotic polar solvent is used as the reaction solvent.

7. The method for manufacturing acid dianhydride according to claim 6, characterized in that, The aprotic polar solvent comprises one or more solvents selected from the group consisting of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone.

8. The method for manufacturing acid dianhydrides according to claim 6 or 7, characterized in that, Following the esterification reaction, a cleaning step using a solvent for washing and / or a purification step for purification are included. The reaction solvent for the esterification includes dimethylformamide and / or dimethylacetamide, and the solvent for the cleaning step and / or purification step is a nitrile solvent.

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