Novel acidic dianhydrides, methods for producing the same, and polyamic acids and polyimides using the same.

Abstract

To provide a novel acidic dianhydride used as a raw material monomer for polyimide that is excellent in heat resistance, low thermal expansion, and mechanical strength while using bio-based raw materials, a method for producing the same, and polyamic acid and polyimide using the same. [Solution] An acidic dianhydride represented by the following chemical formula 1. <Chemical formula 1> JPEG2026142536000007.jpg47166

Description

Technical Field

[0001] The present invention relates to a novel tetracarboxylic dianhydride, a method for producing the same, and a polyamic acid and a polyimide produced using the novel tetracarboxylic dianhydride.

Background Art

[0002] In recent years, with the progress of miniaturization, weight reduction and space saving of electronic devices, demand for flexible printed circuits (FPCs), which are thin, lightweight, flexible and have excellent durability even after repeated bending, has been increasing. Since FPCs enable three-dimensional and high-density mounting even in limited spaces, their applications are expanding to, for example, wiring for movable parts of electronic devices such as HDDs, DVDs and smartphones, as well as components such as cables and connectors. Most FPCs are manufactured by forming a circuit in the metal layer of a metal-clad laminate obtained by laminating a metal layer using metal foil or the like and an insulating resin base material (insulating resin layer).

[0003] Here, polyimide films are widely used in various fields because they have excellent properties in heat resistance, cold resistance, chemical resistance, electrical insulation, mechanical strength and the like. In particular, utilizing the properties of excellent heat resistance and high rigidity, they are widely used as insulating resin layers for FPCs. Above all, it is expected that electronic devices will further increase in functionality and decrease in size going forward. Therefore, for example, for FPCs, it is considered that needs for use in multilayered states will increase, and in response to the thinning of housings of electronic devices such as mobile phones and smartphones, there is an increasing tendency that thinner circuit boards themselves are required. Accordingly, with respect to the thinning of the insulating resin layer accompanying the thinning of the circuit board itself, higher mechanical strength, that is, higher elastic modulus of the polyimide film used for the insulating resin layer is required in order to suppress wrinkles during pattern processing and conveyance. In addition, unless the coefficient of thermal expansion of the polyimide film is close to that of the metal foil, curling occurs due to the difference in coefficient of thermal expansion during heating processing, so control of the coefficient of thermal expansion is important.

[0004] Incidentally, polyimides are manufactured using tetracarboxylic dianhydrides and diamine compounds as raw material monomers. These raw materials have often been produced using petrochemical-derived materials. However, against the backdrop of global warming and the depletion of petroleum resources, there is a growing global demand for environmentally friendly materials using bio-based raw materials such as plants. The use of bio-based raw materials can significantly contribute to carbon neutrality by reducing the use of fossil resources such as petroleum, and can also contribute to the promotion of a circular economy and the formation of a sustainable society. In this context, there is a growing demand for sustainable product development.

[0005] In response to this background and recent demands regarding polyimides, Patent Document 1 proposes a polyimide material that has excellent heat resistance, optical properties, and dielectric properties while increasing its bio-based nature by using tetracarboxylic dianhydrides synthesized from dianhydrohexitols such as isosorbide and isomannide, which are bio-based raw materials and cellulose derivatives, and trimellitic anhydrides. However, the polyimide described in Patent Document 1 has low molecular chain interaction and planarity because the cellulose-derived portion such as isosorbide is alicyclic, leaving room for further improvement in properties such as the aforementioned heat resistance, mechanical strength, and coefficient of thermal expansion.

[0006] Furthermore, Non-Patent Literature 1 investigates etheric acid dianhydrides and diamine monomers using daidzein, which is aromatic and plant-derived. However, the polyimide polymerized with this acidic acid dianhydride and the common diamine monomer 4,4'-oxydianiline exhibited a low glass transition temperature of 302°C, indicating room for improvement in heat resistance. This is presumed to be because the etheric acid dianhydride possesses ether bonds, which are flexible groups within the polyimide, making it prone to molecular motion and poor in planarity. In addition, since this acidic acid dianhydride monomer is synthesized by the etherification reaction of 4-chlorophthalic anhydride and daidzein with a base, the acid anhydride reacts with the base, requiring the use of acids such as acetic anhydride or glacial acetic acid to produce the acid anhydride. This complicates the manufacturing process and results in a high environmental burden. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2023 / 027031 [Non-patent literature]

[0008] [Non-Patent Document 1] ACS Sustainable Chem. Eng. 2023,11,4789-4799. [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention aims to provide a novel acidic dianhydride used as a raw material monomer for polyimide that is excellent in heat resistance, low thermal expansion, and mechanical strength, while using bio-based raw materials, as well as a method for producing the same, and polyamic acid and polyimide using the same. [Means for solving the problem]

[0010] To achieve the above objective, the inventors conducted diligent studies and focused on daidzein, an aromatic bio-based raw material with high planarity. They conceived that by introducing ester bonds, the planarity would be further increased, and interactions between molecular chains would be facilitated, resulting in a structure with excellent heat resistance, low thermal expansion, and mechanical strength. This led to the provision of an acidic dianhydride represented by the following chemical formula 1. In other words, the present invention is an acidic dianhydride represented by the following chemical formula 1.

[0011] <Chemical formula 1> [ka] In this case, it is preferable that the acidic dianhydride has a bio-based content of 10% or more.

[0012] Furthermore, the present invention relates to a polyamic acid containing an acid anhydride residue derived from an acid anhydride component and a diamine residue derived from a diamine component, characterized in that the above-mentioned acid dianhydride is used as the acid anhydride component, and the present invention relates to a polyimide obtained by imidizing the said polyamic acid. In this case, it is preferable that the polyimide is a material for electronic substrates.

[0013] Furthermore, the present invention relates to a method for producing the aforementioned acidic dianhydride, A method for producing acidic dianhydrides, comprising esterifying daidzein or a derivative thereof with trimellitic anhydride halide or trimellitic anhydride using a reaction solvent, characterized in that an aprotic polar solvent is used as the reaction solvent. Here, the aprotic polar solvent preferably includes one or more solvents selected from the group consisting of dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone. Further, in said production method, it is preferable that after the esterification reaction, a washing step of washing with a solvent and / or a purification step of purifying is included, dimethylformamide and / or dimethylacetamide are contained as the esterification reaction solvent, and a nitrile solvent is used as the solvent in the washing step and / or the purification step.

Effects of the Invention

[0014] According to the present invention, a dianhydride having a structure excellent in heat resistance, low thermal expansion property and mechanical strength can be provided while using a bio-based raw material. Further, a polyamic acid and a polyimide using such a dianhydride can be provided. Furthermore, a method for producing said dianhydride can be provided. That is, it becomes possible to provide a novel dianhydride used as a raw material monomer for producing said polyimide and the like. Furthermore, the present invention can contribute to carbon neutrality, circular economy and sustainable product development.

[0015] Further, the polyimide obtained using the dianhydride of the present invention is excellent in heat resistance and the like while using a bio-based raw material, so it can be used not only for FPC but also as a material for electronic substrates. It can be expected to be applied not only to insulating materials used in electronic devices such as semiconductors, and plastic substrates used in liquid crystal displays (LCD), organic electroluminescence (EL) displays, electronic paper, light emitting diode (LED) devices, solar cells, etc., but also to transportation machinery materials such as automobiles. In addition, from the viewpoint of using a bio-based raw material, the dianhydride of the present invention is not limited to use as a monomer for polyimide, and can also be applied to polyamide monomers, polyester modifiers, epoxy resin curing agents and the like.

Brief Description of Drawings

[0016] [Figure 1] Fig. 1 shows the 1H-NMR measurement result of Example 1.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described.

[0018] <The tetracarboxylic acid dianhydride of the present invention> The tetracarboxylic acid dianhydride of the present invention has a structure represented by the above <Chemical Formula 1>. The tetracarboxylic acid dianhydride of the present invention is developed based on new focus on daidzein, which is an aromatic bio-based raw material with high planarity. The present invention is developed based on the finding that by using daidzein and introducing it via an ester bond, higher planarity is achieved, interaction between molecular chains is more likely to occur, and a structure excellent in heat resistance, low thermal expansion property and mechanical strength can be obtained. Since such a novel tetracarboxylic acid dianhydride of the present invention is excellent in heat resistance and the like, it is preferable to have a high melting point and a high thermal decomposition temperature as heat resistance properties. From the viewpoint of these properties, the tetracarboxylic acid dianhydride is preferably used for the aforementioned applications, and is particularly preferably used for producing polyimide and polyamic acid which is a precursor thereof.

[0019] Since the tetracarboxylic acid dianhydride of the present invention is synthesized using daidzein, which is a bio-based raw material, it preferably has a high bio-based content. The bio-based content is preferably 10% or more, more preferably 30% or more, still more preferably 40% or more, and most preferably 100%. Herein, in the present invention, the bio-based content is defined as follows. That is, the biomass content can be confirmed from the bio-based carbon content based on the concentration of radiocarbon that exists only in nature, which is measured in accordance with the standard ASTM D 6866 ( 14 14C). In addition to measuring the bio-based carbon content as described above, it can also be calculated from the ratio of the mass of carbon in the used bio-based raw material. Radiocarbon content is 100% when the carbon is derived only from bio-based raw materials, and 0% when the carbon is derived only from petroleum. When the product is a reactant or composition prepared from raw materials whose bio-based content has been confirmed at the raw material stage, the bio-based content can be simply calculated from the abundance ratio of the raw materials in the reactant or composition.

[0020] <Method for producing acid dianhydrides> <Reaction Process> There are no particular limitations on the method for synthesizing the compound represented by the above <Chemical Formula 1>. For example, one method is an esterification reaction in which daidzein and trimellitic anhydride halide are reacted in the presence of a basic compound and a reaction solvent, as shown in reaction formula 1 below. [Reaction Equation 1] [ka] (In the above reaction equation, X represents a halogen atom.)

[0021] Furthermore, while esterification reactions using trimellitic anhydride halides are not the only options, other methods include directly dehydrating trimellitic anhydride and daidzein at high temperatures, using acid catalysts or coupling agents such as N,N'-dicyclohexylcarbodiimide, and transesterification reactions in which trimellitic anhydride is deacetic acidized at high temperatures with derivatives such as daidzein diacetate. However, from the viewpoint of economy and yield, the method using trimellitic anhydride halides is preferred.

[0022] 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 charging ratio of trimellitic anhydride halide is not particularly limited as long as it is 2 moles or more per mole of daidzein, but it is usually preferably 2 to 6 moles, more preferably 2 to 4 moles, and even more preferably 2 to 3 moles. If it is less than 2 moles, the introduction of acid anhydride groups into daidzein will be insufficient, and it is likely to become a monomer with one or fewer functions, which may inhibit high molecular weight formation in polymerization reactions using this acid dianhydride, for example. On the other hand, if the amount of trimellitic anhydride halide charged is excessive, it is disadvantageous from an economic standpoint, such as having to use a large amount of solvent in purification to remove unreacted trimellitic anhydride halide, so it is preferable to keep it below the above upper limit.

[0023] Since hydrogen halides are generated by the reaction of daidzein with trimellitic anhydride halide, 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 preferably used. Among these, pyridine is more preferable in terms of purification and cost. The charging ratio of the basic compound is not particularly limited as long as it is 2 moles or more relative to the amount of hydrogen halides generated, i.e., daidzein, but it is usually preferably in the range of 2 to 6 moles, more preferably 2 to 4 moles, and even more preferably 2 to 3 moles. If it is less than 2 moles, the generated hydrogen halides cannot be completely contained, and side reactions will occur. On the other hand, if the amount of basic compound charged is excessive, it becomes disadvantageous from an economic standpoint, such as requiring the use of a large amount of solvent in purification to remove unreacted basic compounds, so it is preferable to keep it below the above upper limit.

[0024] The reaction solvent is not particularly limited as long as it is inert to the reaction and the substrate is soluble. Examples of solvents that can be used include 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 aprotic polar solvents such as amide solvents such as dimethylformamide and dimethylacetamide. These reaction solvents may 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 less harmful, and it is even more preferable to use dimethylformamide and dimethylacetamide, which have higher solubility. The amount of reaction solvent used is not particularly limited, as long as it dissolves the substrate, allows the reaction to proceed, and maintains stirring fluidity when the product precipitates as the reaction progresses. For example, a range of 5 to 50 times the weight of daidzein is preferred, a range of 10 to 30 times the weight is more preferred, and a range of 10 to 20 times the weight is even more preferred. If the amount is less than 5 times the weight, the fluidity may decrease when the product precipitates, making it difficult for the reaction to proceed and stirring to be difficult. If the amount is more than 50 times the weight, the product may also dissolve in the solvent, resulting in a decrease in yield.

[0025] There are no particular restrictions on the reaction temperature, 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 or hydrolysis of the product. Conversely, if the reaction temperature is too low, the reaction rate may be slow and the solubility of the substrate may decrease. There are no particular restrictions on the reaction time, but a range of 6 to 36 hours is preferred, and a range of 12 to 24 hours is more preferred. If the reaction time is too short, the reaction may not proceed completely, and if the reaction time is too long, productivity may decrease.

[0026] From the perspective of reducing environmental impact, it is preferable to use bio-based daidzein. Daidzein is abundant in leguminous plants such as soybeans and kudzu, and can be obtained by isolating and purifying them from their seeds, roots, leaves, and stems. From the perspective of food demand, it is preferable to use daidzein other than that derived from soybean seeds, and it is even more preferable to use daidzein derived from kudzu.

[0027] There are no particular restrictions on the method for recovering the target compound, and it is preferable to change it as appropriate depending on the reaction solvent. For example, when a halogen-based solvent is used, the target compound dissolves in the solvent, and a salt of hydrogen halide and a basic compound precipitates. In this case, the salt can be filtered off, and the filtrate can be added dropwise to a poor solvent to precipitate the target compound, or the solvent of the filtrate can be removed by distillation under reduced pressure. In the case of nitrile-based solvents such as acetonitrile or amide-based solvents such as dimethylacetamide, the target compound precipitates, and a salt of hydrogen halide and a basic compound dissolves in the solvent. In this case, the target compound can be recovered by filtering it off. In the case of ether-based solvents such as tetrahydrofuran, both the target compound and a salt of hydrogen halide and a basic compound precipitate. In this case, a large amount of pure water can be added to the filtrate to dissolve and remove the salt of hydrogen halide and a basic compound. In the present invention, it is preferable to use an amide-based solvent with high solubility of daidzein, so in this case, it is preferable to filter off the precipitated target compound as the recovery method.

[0028] When an amide solvent such as dimethylacetamide is used as the reaction solvent, the amide solvent tends to remain in the target compound after filtration and recovery. If a large amount of amide solvent remains, yellow discoloration may occur during drying and during dehydration and ring closure by heating of the dicarboxylic acid, as described later. Furthermore, because amide solvents have high surface tension and significantly poor filterability, it is preferable to reduce the amount of amide solvent remaining and improve filterability by adding an aprotic polar solvent with low surface tension to the reaction solvent after the reaction is complete. As the aprotic polar solvent, it is preferable to use a nitrile solvent such as acetonitrile, from the viewpoint that the target compound is difficult to dissolve, has high affinity for amide solvents, and is a solvent that dissolves hydrogen halides and salts of basic compounds. As the nitrile solvent, acetonitrile, propionitrile, and butyronitrile are preferred, and acetonitrile is more preferred. The amount of solvent to add is preferably 0.5 to 3 times the weight of the amide reaction solvent, and more preferably 0.75 to 2 times the weight. If the amount of solvent is small, the amide solvent tends to remain, and the filterability does not improve. If the amount of solvent is too large, the amount of filtration will be large, which is disadvantageous in terms of productivity, and the increased solvent usage will also be disadvantageous from an economic standpoint.

[0029] <Washing process> To reduce the amount of residual amide solvent after filtration and recovery, it is preferable to wash the target compound with an aprotic polar solvent after filtration and recovery. For the same reasons as above, it is preferable to use a nitrile solvent such as acetonitrile as the washing solvent. The amount of washing solvent is preferably 0.5 to 3 times the weight of the reaction solvent, and more preferably 0.75 to 2 times the weight. If the amount of washing solvent is too small, the amide solvent is more likely to remain, and if the amount of solvent is too large, the amount to be filtered will be large, which is disadvantageous in terms of productivity and is disadvantageous in terms of economy because the amount of solvent used will increase.

[0030] <Drying process> After washing, the target compound recovered by filtration is preferably dried to reduce the amount of residual amide solvent. The drying temperature is preferably 50 to 120°C, and more preferably 80 to 100°C. If the drying temperature is too high, the decomposition of the amide solvent will progress, which may cause yellow discoloration. Conversely, if the drying temperature is too low, the amount of amide solvent removed will be small. The drying time is preferably 2 to 24 hours, and more preferably 5 to 12 hours. A long drying time is disadvantageous in terms of productivity and economics, while a short drying time will result in the removal of less amide solvent. There are no particular restrictions on the drying pressure, whether at atmospheric pressure or under reduced pressure, but it is preferable to perform the drying under reduced pressure of about 1 to 10 kPa, as this allows for more efficient removal of the solvent.

[0031] <Purification process> After drying, the target compound is preferably purified to reduce the amount of residual amide solvent and other impurities. While there are no particular restrictions on the purification method, examples include recrystallization and reslurrying, where the target compound is suspended in a solvent and crystallized. In recrystallization, the target compound is dissolved in the solvent while heating, and crystals are precipitated by cooling. However, in reslurrying, it is not necessary to dissolve the entire target compound. Considering that the acidic dianhydride of the present invention has relatively low solubility in organic solvents, applying reslurrying is more preferable. While there are no particular restrictions on the solvent used in reslurrying, it is preferable to use a nitrile solvent such as acetonitrile, which has high affinity for amide solvents. The amount of solvent is preferably 5 to 20 times the weight of the target compound, and more preferably 7 to 10 times the weight. Too little solvent results in insufficient purification, while too much solvent causes over-dissolution of the target compound, reducing the yield. In reslurrying, it is necessary to heat the solvent and the target compound, with the temperature preferably in the range of 40 to 100°C, and more preferably in the range of 60 to 85°C. If the temperature is too low, crystallization will be insufficient, and if the temperature is too high, hydrolysis of the target compound is likely to occur.

[0032] <Dehydration process> After purification, the target compound recovered by filtration is prone to partial ring-opening of the acid dianhydride via hydrolysis, forming a dicarboxylic acid. Therefore, it is preferable to dehydrate it to form an acid dianhydride. There are no particular restrictions on the dehydration method, but methods using acetic anhydride or dehydration by heating the solid are possible. When using acetic anhydride, acid-resistant equipment is required, and impurities such as acetic acid esters are likely to be formed, so dehydration by heating is preferred. When performing dehydration by heating, the heating temperature is preferably in the range of 120 to 170°C, and more preferably in the range of 150 to 160°C. If the temperature is too low, the dehydration reaction proceeds slowly, and if the temperature is too high, the yield decreases due to sublimation or decomposition proceeds more easily. There are no particular restrictions on the pressure during heating, whether at atmospheric pressure or under reduced pressure, but it is preferable to carry it out under reduced pressure of about 1 to 10 kPa, as this allows the dehydration reaction to proceed more efficiently. The heating time is preferably 2 to 24 hours, and more preferably 6 to 12 hours. If the heating time is too short, the dehydration reaction will not proceed completely, and if the heating time is too long, productivity will decrease.

[0033] Furthermore, the order of the steps after filtration following the reaction described above—washing → drying → purification → dehydration—is not limited to this order and may be changed from the perspective of reducing residual amide solvents and the resulting discoloration, as well as reducing the amount of impurities. For example, the order may be washing → drying → dehydration → purification. Also, washing and purification may be performed multiple times.

[0034] <Polyamic acid and polyimide of the present invention> Furthermore, from another viewpoint, the present invention relates to a polyamic acid containing an acid anhydride residue derived from an acid anhydride component and a diamine residue derived from a diamine component, characterized in that the aforementioned acid dianhydride is used as the acid anhydride component. The polyamic acid is a precursor of polyimide, and is composed of the acid anhydride residue and the diamine residue, and when these components are linked together and considered as a single repeating unit, it is composed of polymers of that repeating unit. The present invention also relates to a polyimide obtained by dehydrating and cyclizing this polyamic acid by imidation. 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 cyclizing the polyamic acid by imidation.

[0035] The aforementioned diamine is not particularly limited, and various diamines used in the conventional synthesis of polyimides can be used. Specifically, these 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, diaminodiphenylsulfone, diaminobenzophenone, 4,4'-diaminobenzanilide, and diaminonaphthalene. Examples include aromatic diamines such as 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)diphenylsulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 2,2'-trifluoromethyl-4,4'-diaminobiphenyl; alicyclic diamines such as 1,4-diaminocyclohexane, 1,4-cyclohexanebis(methylamine), and 4,4'-diaminodicyclohexylmethane; and aliphatic diamines such as tetramethylenediamine and hexamethylenediamine. These diamines can also be used individually or in combination of two or more.

[0036] Furthermore, in the polyamic acid and polyimide of the present invention, if the acid dianhydride represented by <Chemical Formula 1> is used as the acid anhydride component, other acid anhydride components may be used in combination as long as they do not impair the objectives of the present invention. Such other acid anhydride components are not particularly limited, and various acid dianhydrides used in the conventional synthesis of polyimides can be used. One type of other acid anhydride component may be used alone, or two or more types may be used in combination. The amount of other acid anhydride components (acid anhydride residues) used is preferably 50 mol% or less, more preferably 25 mol% or less, and even more preferably 10 mol% or less, based on 100 mol% of the total acid anhydride components (total acid anhydride residues). From the viewpoint of bio-basedness, it is particularly preferable not to use other acid dianhydride components (acid anhydride residues) in combination (0 mol%).

[0037] In the polyamic acid and polyimide of the present invention, since the acid anhydride component (acid anhydride residue) is an acid dianhydride (acid dianhydride residue) represented by the above-mentioned <Chemical Formula 1>, it is preferable that they have a high biobase, and the biobase is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and most preferably 30%.

[0038] The method for obtaining the polyamic acid of the present invention is not particularly limited, and may be obtained by reacting an acid anhydride component containing the acid dianhydride represented by <Chemical Formula 1> with a diamine component by a known production method and polymerizing them. A simple method involves mixing the acid anhydride component containing the acid dianhydride represented by <Chemical Formula 1> with the diamine component in an organic solvent and reacting them. For example, the polyamic acid can be obtained by dissolving the acid anhydride component and the diamine component in approximately equimolar amounts in an organic solvent and carrying out a polymerization reaction by stirring at a temperature usually in the range of 0 to 100°C for 30 minutes to 24 hours. In the reaction, the reactants are dissolved in the organic solvent in a range of 5 to 30% by weight, preferably 10 to 20% by weight, to produce a precursor.

[0039] Specific examples of organic solvents used in this process 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 may be used individually or in combination of two or more. Furthermore, even solvents that do not dissolve polyamic acid may be added to the aforementioned solvents as long as a homogeneous solution can be obtained.

[0040] Furthermore, the molecular weight (Mw) of the polyamic acid is preferably in the range of 1,000 to 100,000, more preferably in the range of 5,000 to 100,000, and even more preferably in the range of 10,000 to 90,000. If the molecular weight is too low, the viscosity of the polyamic acid varnish will be low, raising concerns about a decrease in mechanical properties such as elongation. If the molecular weight is too high, the viscosity of the polyamic acid varnish will be high, making it difficult to apply to the 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, and more preferably in the range of 5,000 to 50,000 cp.

[0041] In the present invention, the method for obtaining polyimide by dehydrating and cyclizing polyamic acid by imidation is not particularly limited, but, as with ordinary polyamic acid, a method of cyclization by heating or chemical cyclization using a known dehydration and cyclization catalyst can be employed. The heating method can be carried out in steps within any temperature range of 100 to 400°C, preferably 200 to 350°C.

[0042] Furthermore, there are no restrictions on the method of obtaining the polyimide as a polyimide layer or polyimide film, and known methods can be used. For example, it can be formed by a method in which a solution of polyamic acid is applied to a support substrate (e.g., a metal layer), dried, and then imidized to produce a resin film (so-called casting method), or by a method in which a solution of polyamic acid is applied to a support substrate, dried, the polyamic acid gel film is peeled off the support substrate, and then imidized to produce a resin film. In addition, when it consists of multiple polyimide layers, examples of the manufacturing method include, for example, a method in which a solution of polyamic acid is applied to a support substrate multiple times, dried, and then imidized (so-called sequential coating method), or a method in which a polyamic acid laminated structure is applied to a support substrate by multilayer extrusion, dried simultaneously, and then imidized (so-called multilayer extrusion method).

[0043] As described above, the polyimide of the present invention obtained in this manner is obtained using daidzein, an aromatic bio-based raw material with high planarity, and an acid anhydride component with high planarity due to the introduction of ester bonds. Therefore, it has been confirmed to have excellent heat resistance, low thermal expansion, and mechanical strength.

[0044] Regarding such heat resistance, the polyimide of the present invention preferably has high heat resistance, with a glass transition temperature (Tg) of 300°C or higher. More preferably, it is 350°C or higher, and even more preferably, 380°C or higher. Furthermore, 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.

[0045] Furthermore, regarding low thermal expansion, the polyimide of the present invention has a coefficient of thermal expansion (CTE) of 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. The lower limit is not restricted, but it should be 1 ppm / K or higher.

[0046] Thus, the polyimide using the acid dianhydride of the present invention, while using bio-based raw materials, exhibits excellent heat resistance and other properties, making it particularly suitable for use as an electronic substrate material, not limited to FPCs. For example, it is suitably used in core layers and build-up layers of laminates, printed circuit boards, and multilayer substrates, resin-coated copper foil, copper-clad laminates, TAB films, and prepregs used in these applications. All of these electronic substrate materials can be manufactured using known methods.

[0047] Furthermore, the polyimide of the present invention is expected to be applicable not only to insulating materials used in electronic devices such as semiconductors, and to plastic substrates used in liquid crystal displays (LCDs), organic electroluminescent (EL) displays, electronic paper, light-emitting diode (LED) devices, and solar cells, but also to materials for transportation machinery such as automobiles. In addition, from the viewpoint of using bio-based raw materials, the acidic dianhydride of the present invention is not limited to monomers for polyimide, but can also be applied to polyamide monomers, polyester modifiers, epoxy resin curing agents, and the like. [Examples]

[0048] The present invention will be described in detail below based on the examples, but the present invention is not limited to the scope of these examples.

[0049] The abbreviations used in this example indicate the following compounds. Dz-TME: Acid dianhydride represented by chemical formula 1 obtained in Example 1 PDA: Paraphenylenediamine m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl 4,4'-DAPE:4,4'-diaminodiphenyl ether DABA:4,4'-diaminobenzanilide APAB: 4-aminophenyl-4-aminobenzoate DMAc: N,N-dimethylacetamide

[0050] The analytical methods used in the examples were as follows.

[0051] < 1 H-NMR> The NMR spectra of the synthesized acidic dianhydrides were measured using a JNM-ECZ400R / S nuclear magnetic resonance spectrometer (JEOL Corporation) after dissolving the acidic dianhydrides in deuterated dimethyl sulfoxide (DMSO-d6).

[0052] <Differential thermal / thermogravimetric analysis (TG-DTA)> 5-7 mg of the synthesized acidic dianhydride was weighed into an aluminum pan, and the melting point and thermal decomposition temperature were evaluated using a differential thermal thermogravimetric analyzer (Hitachi High-Tech Science Corporation: STA7200) under the following operating conditions. (Operating conditions) Heating rate: 10℃ / min Measurement temperature range: 50~500℃ Measurement atmosphere: Nitrogen 200 mL / min

[0053] [Viscosity measurement] 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 Co., Ltd.).

[0054] [Weight average molecular weight (Mw)] The measurements were performed using gel permeation chromatography (manufactured by Tosoh Corporation, product name: HLC-8220GPC). Polystyrene was used as the standard substance, and N,N-dimethylacetamide was used as the developing solvent.

[0055] [Tensile modulus of elasticity, tensile elongation] Test specimens of polyimide film (10 mm x 15 mm) were prepared, and tensile tests were performed using a Tensilon universal testing machine (Orientec Co., Ltd., RTA-250) at a tensile speed of 10 mm / min in accordance with IPC-TM-650, 2.4.19, to calculate the tensile modulus and tensile elongation.

[0056] [Coefficient of thermal expansion (CTE)] A polyimide film obtained by etching copper foil was cut to a size of 3 mm x 20 mm. Using a thermomechanical analyzer (Hitachi High-Tech Science Corporation, product name: TMA7100), the film was heated from 30°C to 260°C at a heating rate of 10°C / min while applying a load of 49 mN. After holding the film at that temperature for 10 minutes, it was cooled at a rate of 10°C / min, and the average thermal expansion coefficient from 250°C to 100°C was determined.

[0057] [Thermal decomposition temperature (Td5)] Under a nitrogen atmosphere, a polyimide film weighing 10-20 mg was heated at a constant rate from 30°C to 550°C using a thermogravimetric analyzer (TG). The weight change was measured, and the weight at 200°C was set to zero. The temperature at which the weight loss rate was 5% was defined as the thermal decomposition temperature (Td5).

[0058] [Glass transition temperature (Tg)] The dynamic viscoelasticity of a resin film (10 mm × 22.6 mm) was measured using a dynamic thermomechanical analyzer when the temperature was increased from 20°C to 400°C at a rate of 10°C / min. The inflection point at which the storage modulus rapidly decreases to 1.0 × 10⁹ Pa or less was defined as the glass transition temperature.

[0059] [FCCL Carl] The curl of FCCL was observed after applying a polyamic acid solution to copper foil, drying it, and then cooling it. A ○ was used to indicate that the copper foil had a larger coefficient of thermal expansion than the polyimide, resulting in curling along the copper foil side; a ◎ was used when the coefficients of thermal expansion of the polyimide and copper foil were equivalent, resulting in no curl; a △ was used when the polyimide had a slightly larger coefficient of thermal expansion than the copper foil, resulting in slight curling along the polyimide side; and a × was used when the polyimide had a larger coefficient of thermal expansion than the copper foil, resulting in significant curling along the polyimide side.

[0060] [Example 1] <Synthesis of acid dianhydrides represented by chemical formula 1 (Synthesis example 1)> 20.2 g (96.0 mmol) of trimellitic chloride anhydride was added to a 500 ml separable flask with a dropping funnel inserted. While purging with nitrogen, 100 g of dimethylacetamide was added, and the mixture was stirred in an ice bath until the trimellitic chloride anhydride dissolved. 10.2 g (40.1 mmol) of daidzein (derived from kudzu root), 100 g of dimethylacetamide, and 9.5 g (120.0 mmol) of pyridine were added to a 200 ml round-bottom flask, and the mixture was stirred until the daidzein dissolved, then poured into a dropping funnel. While stirring the trimellitic chloride anhydride solution in an ice bath, the daidzein solution was added dropwise from the dropping funnel over 1 hour, and then stirred for another hour. After that, the mixture was stirred at room temperature for 24 hours while purging with nitrogen, resulting in a pale yellow slurry. 150 g of acetonitrile was added to the slurry, stirred for 5 minutes, and then the precipitate was filtered by suction. 150 g of acetonitrile and the filtrate were placed in a 500 ml separable flask, stirred and washed for 10 minutes, and then filtered again by vacuum. The filtrate was vacuum dried at 100°C for 6 hours to obtain 21.1 g of pale yellow crude product (yield 88%). 21.1 g of the crude product and 150 g of acetonitrile were placed in a 500 ml round-bottom flask, heated under reflux and stirred at 85°C for 1 hour, and then returned to room temperature for a reslurry procedure. The precipitated solid was filtered by vacuum, vacuum dried at 100°C for 3 hours, and then vacuum dried at 160°C for 10 hours to dehydrate and closure the ring, obtaining 12.0 g of milky white solid (yield 49.8%).

[0061] The milky white solid obtained 1 As shown in Figure 1, the 1H-NMR measurement results revealed a peak with the following chemical shift, confirming that it is an acidic dianhydride represented by <Chemical Formula 1>. <1> ~ <9> These correspond to the symbols in Figure 1. 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> )

[0062] Furthermore, thermogravimetric differential thermal analysis revealed that the 1% thermogravimetric loss temperature relative to 100°C was 266°C and the 5% thermogravimetric loss temperature was 406°C, indicating high heat resistance. The same measurement also revealed a sharp endothermic peak with a peak top at 290.8°C, confirming a high melting point and purity of 290.8°C. The melting point of the daidzein ether acid anhydride in Non-Patent Document 1 is 229.6°C, suggesting that the polyimide using the acid dianhydride in this invention exhibits higher heat resistance and glass transition temperature. Additionally, the biobase of the obtained acid dianhydride was calculated to be 45%.

[0063] (Synthesis Examples 2-6) To synthesize the polyamic acid solutions described in Synthesis Examples 2-6, DMAc solvent was added to a 100 ml separable flask under a nitrogen atmosphere to achieve the solid content concentration shown in Table 1. The diamine and acid anhydride components (molar parts) shown in Table 1 were then added, and the mixture was stirred at room temperature for 10 hours to carry out the polymerization reaction and prepare a viscous solution of polyamic acid. The bio-based content of the obtained polyamic acids was calculated to be between 32% and 38%, respectively.

[0064] [Table 1]

[0065] [Evaluation of the physical properties of polyimide films] (Examples 2-6) Next, polyamic acid solutions A to E, prepared according to Synthesis Examples 2 to 6 as shown in Table 1, were applied to copper foil (electrolytic copper foil, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., product name: CF-T49A-DS-HD2-12, thickness: 12 μm, Rz = 1.2 μm) so that the thickness after curing was as shown in Table 2. The solutions were then heated and dried at 90 to 140°C to remove the solvent. Subsequently, metal-clad laminates (CCLs) were fabricated by gradually increasing the temperature in the range of 130 to 360°C to laminate an insulating resin layer consisting of a polyimide layer on the copper foil. To evaluate the properties of the polyimide layer in each metal-clad laminate, the copper foil was etched off to prepare resin films, which were then evaluated. The evaluation results are shown in Table 2.

[0066] [Table 2]

[0067] Although evaluating the physical properties of homopolymer films with PDA, DABA, and APAB was difficult due to their brittleness, it was found from FCCL curl that they had a CTE (less than 25 ppm / K) that was lower than or equivalent to that of copper foil, indicating a low coefficient of thermal expansion. Furthermore, homopolymer films with m-TB and 4,4'-DAPE had a higher CTE than copper foil, but showed no decrease in storage modulus up to 380°C, revealing extremely high heat resistance. [Industrial applicability]

[0068] The novel acidic dianhydride of the present invention contains bio-based raw materials and is suitably applicable to 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, and the like. Furthermore, it can be used as a material for electronic substrates, as an insulating material used in electronic devices such as semiconductors, and also to plastic substrates used in liquid crystal displays (LCDs), organic electroluminescent (EL) displays, electronic paper, light-emitting diode (LED) devices, and solar cells. In addition, it is expected to be applicable to materials for transportation machinery such as automobiles.

Claims

1. The acidic dianhydride represented by the following chemical formula 1. <Chemical formula 1> 【Chemistry 1】

2. The acidic dianhydride according to claim 1, characterized in that it has a bio-based content of 10% or more.

3. A polyamic acid containing acid anhydride residues derived from an acid anhydride component and diamine residues derived from a diamine component, A polyamic acid characterized by using the acid dianhydride described in claim 1 as the acid anhydride component.

4. A polyimide obtained by imidizing the polyamic acid described in claim 3.

5. The polyimide according to claim 4, characterized in that it is for use as a material for electronic circuit boards.

6. A method for producing the acid dianhydride described in claim 1, A method for producing acidic dianhydrides, comprising esterifying daidzein or a derivative thereof with trimellitic anhydride halide or trimellitic anhydride using a reaction solvent, characterized in that an aprotic polar solvent is used as the reaction solvent.

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

8. A method for producing an acidic dianhydride according to claim 6 or 7, comprising a washing step of washing with a solvent and / or a purification step of purifying after the esterification reaction, wherein the esterification reaction solvent includes dimethylformamide and / or dimethylacetamide, and the solvent for the washing step and / or purification step is a nitrile-based solvent.

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