Polyamic acid composition, production method for said polyamic acid composition, polyimide, polyimide film, laminate, and production method for said laminate

Abstract

The purpose of the present invention is to provide a polyamic acid composition containing a polyamic acid that has a suitable viscosity and is obtained by specifically using a cyclic ketone-based solvent as an organic solvent in which a diamine component and a tetracarboxylic acid dianhydride component undergo a satisfactory addition polymerization reaction.　The present invention is a polyamic acid composition containing an organic solvent and a polyamic acid that is the product of an addition reaction between a diamine component and a tetracarboxylic acid dianhydride component in the organic solvent, wherein the organic solvent contains a cyclic ketone-based solvent, and the tetracarboxylic acid dianhydride component contains a compound that has diphenyl ether group in each molecule. The tetracarboxylic acid dianhydride component more preferably includes a compound having at least two diphenyl ether groups in each molecule.

Description

Polyamic acid composition, method for producing the polyamic acid composition, polyimide, polyimide film, laminate, and method for producing the laminate

[0001] The present invention relates to a polyamic acid composition containing a specific organic solvent and a polyamic acid obtained by polyaddition reaction of a diamine component and a tetracarboxylic dianhydride component in the organic solvent.

[0002] Polyimide is excellent in heat resistance, mechanical strength, electrical insulation, chemical resistance, etc., and is used in various electronic component materials.

[0003] Polyimide is generally obtained by reacting a diamine component and a tetracarboxylic dianhydride component in an organic solvent to form a solution containing a polyamic acid which is a polyimide precursor (also referred to as "polyamic acid composition" or "varnish"), and then further subjecting it to thermal or chemical ring closure. Also, in the production of a laminate containing a polyimide film as an electronic component material or the like, a polyamic acid solution is applied to at least one side of a substrate (support) made of a metal or the like constituting the laminate to form a coating film, and after volatilizing and removing the organic solvent, imidization is performed to form a polyimide film. A method is known.

[0004] Here, polyimide, its precursor polyamic acid, and the diamine component and tetracarboxylic dianhydride component which are its raw material monomers have low solubility in organic solvents. Conventionally, amide solvents have been frequently used as organic solvents. However, amide solvents are suspected of being carcinogenic, and it is desired to avoid their use from the viewpoint of REACH regulations and the like.

[0005] In view of such circumstances, it has been proposed to use a more safe organic solvent, for example, a ketone solvent such as cyclohexanone or methyl ethyl ketone (for example, Patent Document 1). The technique of Patent Document 1 has as its technical problem to provide a polyamic acid (polyimide precursor) obtained by reacting a diamine component and a tetracarboxylic dianhydride component under solvent-free conditions and having excellent solubility in a ketone solvent.

[0006] However, certain organic solvents, such as ketone solvents, not only affect the solubility of polyamic acids obtained by the polyaddition reaction of diamine and tetracarboxylic dianhydride components, but also influence the reactivity of the polyaddition reaction of the starting monomers. In other words, not all combinations of the numerous known diamine and tetracarboxylic dianhydride components will undergo appropriate polyaddition reactions in organic solvents such as ketone solvents.

[0007] Furthermore, among ketone solvents, cyclic ketone solvents such as cyclohexanone and cyclopentanone differ significantly from linear ketone solvents such as methyl ethyl ketone not only in their solubility of polyamic acid but also in their reactivity with the diamine component and tetracarboxylic dianhydride component required for polyamic acid synthesis.

[0008] Poor reactivity in the polyaddition reaction between the diamine component and the tetracarboxylic dianhydride component in certain organic solvents, such as ketone solvents, can not only prevent the formation of polyamic acid with an appropriate molecular weight, but also lead to a decrease in the viscosity of the polyamic acid solution. Furthermore, poor reactivity can also cause an increase in the viscosity of the polyamic acid solution, as well as solidification or gelation.

[0009] Thus, in order to obtain a polyamic acid solution that exhibits excellent coating properties on a substrate and can form a uniform polyimide film on that substrate, not only the solubility of the synthesized polyamic acid in an organic solvent is important, but the reactivity of the diamine component and the tetracarboxylic dianhydride component in that organic solvent is also extremely important.

[0010] Japanese Patent Publication No. 2023-146193

[0011] This invention was proposed in view of the above circumstances, and aims to provide a polyamic acid composition containing a polyamic acid having an appropriate viscosity, obtained by a good polyaddition reaction between a diamine component and a tetracarboxylic dianhydride component in an organic solvent, particularly a cyclic ketone solvent, in the organic solvent.

[0012] The inventors diligently conducted research to solve the above-mentioned problems. As a result, they discovered that by using a tetracarboxylic dianhydride component containing a compound having a specific structure in a cyclic ketone solvent, a polyaddition reaction proceeds smoothly with the diamine component, resulting in a polyamic acid solution of appropriate viscosity, thus completing the present invention.

[0013] (1) The first invention of the present invention is a polyamic acid composition comprising an organic solvent and a polyamic acid which is a polyaddition reaction product of a diamine component and a tetracarboxylic dianhydride component in the organic solvent, wherein the organic solvent comprises a cyclic ketone solvent and the tetracarboxylic dianhydride component comprises a compound having a diphenyl ether group in its molecule.

[0014] (2) The second invention of the present invention is a polyamic acid composition in which, in the first invention, the content of the compound having a diphenyl ether group in the molecule is 80 mol% or more relative to the total tetracarboxylic dianhydride component.

[0015] (3) The third invention of the present invention is a polyamic acid composition in which, in the first or second invention, the tetracarboxylic dianhydride component comprises a compound having two or more diphenyl ether groups in its molecule.

[0016] (4) The fourth invention of the present invention is a polyamic acid composition in which, in any of the first to third inventions, the content of a compound having two or more diphenyl ether groups in the molecule is 80 mol% or more relative to the total tetracarboxylic dianhydride component.

[0017] (5) The fifth invention of the present invention is a polyamic acid composition in which, in any of the first to fourth inventions, the compound having a diphenyl ether group in the molecule comprises one or more selected from 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic acid anhydride and 4,4'-oxydiphthalic acid anhydride.

[0018] (6) The sixth invention of the present invention is a polyamic acid composition in which, in any of the first to fifth inventions, the diamine component comprises one or more selected from m-phenylenediamine and m-tolidine.

[0019] (7) The seventh invention of the present invention is a polyamic acid composition in which, in any of the first to sixth inventions, the total content of one or more diamine components selected from m-phenylenediamine and m-tolidine is 80 mol% or more of the total diamine components.

[0020] (8) The eighth invention of the present invention is a polyamic acid composition in which, in any of the first to seventh inventions, the diamine component comprises an aliphatic diamine or a siloxanediamine, the content of the aliphatic diamine or siloxanediamine is 30 mol% or less with respect to the total diamine component, provided that the content of the total diamine component is 100 mol%.

[0021] (9) The ninth invention of the present invention is a polyamic acid composition in which, in any of the first to eighth inventions, the diamine component comprises an aliphatic diamine or a siloxanediamine, the content of the aliphatic diamine or siloxanediamine is 10 mol% or less with respect to the total diamine component, provided that the content of the total diamine component is 100 mol%.

[0022] (10) The tenth invention of the present invention is a polyamic acid composition in which, in any of the first to ninth inventions, the molar ratio expressed as the total amount of the tetracarboxylic dianhydride component / the total amount of the diamine component is greater than 0.9 and less than 1.2.

[0023] (11) The eleventh invention of the present invention is a polyamic acid composition in which the cyclic ketone solvent is contained in an amount of 70% by mass or more relative to the total amount of the organic solvent, in any of the first to tenth inventions.

[0024] (12) The twelfth invention of the present invention is a polyamic acid composition in which, in any of the first to eleventh inventions, the cyclic ketone solvent comprises one or more selected from cyclohexanone and cyclopentanone.

[0025] (13) The thirteenth invention of the present invention is a method for producing a polyamic acid composition comprising a polyamic acid obtained by polyaddition reaction of a diamine component and a tetracarboxylic dianhydride component in an organic solvent, wherein the diamine component and a tetracarboxylic dianhydride component comprising a compound having a diphenyl ether group in its molecule are mixed in an organic solvent containing a cyclic ketone solvent.

[0026] (14) The fourteenth invention of the present invention is a polyimide, which is an imide of a polyamic acid contained in the polyamic acid composition described in any of the first to twelfth inventions.

[0027] (15) The fifteenth invention of the present invention is a polyimide film containing the polyimide described in the fourteenth invention.

[0028] (16) The sixteenth invention of the present invention is a laminate having a substrate and a polyimide film according to the fifteenth invention formed on one or both sides of the substrate.

[0029] (17) The seventeenth invention of the present invention is a method for manufacturing a laminate comprising a substrate and a polyimide film, comprising the steps of: coating one or both sides of the substrate with a polyamic acid composition according to any one of the first to twelfth inventions to form a coating film containing the polyamic acid; and heating the coating film to imide the polyamic acid to form a polyimide film.

[0030] According to the present invention, a polyamic acid composition can be provided that contains a polyamic acid having an appropriate viscosity, obtained by a good polyaddition reaction between a diamine component and a tetracarboxylic dianhydride component in an organic solvent containing a cyclic ketone solvent.

[0031] The following describes specific embodiments of the present invention in detail. However, the present invention is not limited to the following embodiments and can be implemented with various modifications without altering the essence of the invention.

[0032] ≪1. Polyamic Acid Composition≫ The polyamic acid composition according to this embodiment comprises an organic solvent and a polyamic acid obtained by a polyaddition reaction between a diamine component and a tetracarboxylic dianhydride component in the organic solvent. Thus, the polyamic acid composition comprises a specific organic solvent and a polyamic acid which is a reaction product obtained by a good polyaddition reaction between monomer components in the organic solvent.

[0033] A "polyamic acid composition" is a solution in which polyamic acid is dissolved in an organic solvent (hereinafter also referred to as a "polyamic acid solution"), and is also called a varnish. Polyamic acid is a precursor of polyimide. The polyamic acid solution is used by coating it onto the surface of a substrate (support) made of metal or the like, and by heating the coating film, the polyamic acid is imidized to form a polyimide film. Therefore, it is preferable that the polyamic acid solution has excellent coating properties, has an appropriate viscosity, and does not solidify or gel.

[0034] Specifically, the polyamic acid solution according to this embodiment contains a cyclic ketone solvent as the organic solvent. Furthermore, the tetracarboxylic dianhydride component is characterized by containing a compound having a diphenyl ether group in its molecule.

[0035] Numerous compounds are known as the diamine and tetracarboxylic dianhydride components that serve as the starting monomers for polyamic acids. When polyamic acids are synthesized by polyaddition reactions of these monomer components in organic solvents, the reactivity of the monomer components is greatly influenced by the type of organic solvent, and the reactivity in a particular organic solvent varies depending on the type and combination of starting monomers.

[0036] As a result of the inventors' research, it was found that in organic solvents containing cyclic ketone solvents, using a compound having a diphenyl ether group in its molecule as the tetracarboxylic dianhydride component reacts well with the diamine component to obtain a polyamic acid solution with appropriate viscosity. Such a polyamic acid solution exhibits excellent solubility of the polyamic acid in its organic solvent and also has excellent coating properties for substrates.

[0037] [Organic solvent] The polyamic acid solution contains a cyclic ketone solvent as the organic solvent. In this embodiment, the polyamic acid solution is obtained by a polyaddition reaction between a diamine component and a tetracarboxylic dianhydride component in an organic solvent containing the cyclic ketone solvent, and the polyaddition product, polyamic acid, is dissolved in the cyclic ketone solvent.

[0038] Cyclic ketone solvents are among the safest organic solvents and exhibit excellent solubility of the resulting polyamic acid.

[0039] As shown in the examples described later, even with similar ketone solvents, for example, with linear ketone solvents such as methyl ethyl ketone (MEK), the reactivity differs even when the same starting monomer is used for the polyaddition reaction, resulting in solidification or gelation. Furthermore, even when polyamic acid is produced, there is a significant difference in the solubility of that polyamic acid. In other words, depending on the type of organic solvent, there is a significant difference in the reactivity between the starting monomer diamine component and the tetracarboxylic dianhydride component in that organic solvent.

[0040] The cyclic ketone solvent is not particularly limited, but examples include cyclobutanone, cyclopentanone, cyclohexanone, and cycloheptanone, which are preferably used. These cyclic ketone solvents may have substituents as long as they do not impair the effects of the present invention, for example, 2-methylcyclobutanone, 3-methylcyclopentanone, 3-methylcyclohexanone, 4-cycloheptanone, etc. From the viewpoint of solubility of polyamic acid, it is preferable that the cyclic ketone solvent contains either cyclopentanone, cyclohexanone, or both.

[0041] Further, as the organic solvent, a mixed solvent containing the above-described cyclic ketone-based solvent as a main component and other types of organic solvents may be used as long as the reactivity of the selected raw material monomer is not impaired. The main component refers to a component contained at a ratio of 51% by mass or more based on the total amount of the organic solvent. Among them, the cyclic ketone-based solvent is preferably contained at 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more based on the total amount of the organic solvent. In particular, it is particularly preferable that the total amount of the organic solvent is a cyclic ketone-based solvent.

[0042] Further, as the organic solvent, it is preferable not to contain amide-based solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DFM), N-methylpyrrolidone (NMP), and N-butyl-2-pyrrolidone (NBP).

[0043] [Polyamic acid] Polyamic acid contains structural units derived from a diamine component and a tetracarboxylic dianhydride. Specifically, polyamic acid is a reaction product obtained by a polyaddition reaction of a diamine component, which is a raw material monomer, and a tetracarboxylic dianhydride component. Polyamic acid is a precursor of polyimide, and it becomes polyimide by dehydrative cyclization (imidization) of the polyamic acid.

[0044] The polyamic acid contained in the polyamic acid solution according to the present embodiment is obtained by polyaddition reaction of raw material monomers in an organic solvent containing a cyclic ketone-based solvent, which is a specific organic solvent. Therefore, it becomes a polyamic acid solution in which polyamic acid is dissolved in the organic solvent as it is.

[0045] If the diamine component and the tetracarboxylic dianhydride component undergo a good polyaddition reaction in an organic solvent containing a cyclic ketone solvent, a polyamic acid of an appropriate molecular weight is produced in the organic solvent, resulting in a polyamic acid solution with appropriate viscosity in which the polyamic acid is uniformly dispersed. Such a polyamic acid solution has excellent coating properties for substrates (supports) made of metals, etc., and makes it possible to form a good polyimide film. On the other hand, if the polyaddition reaction between the diamine component and the tetracarboxylic dianhydride component in an organic solvent containing a cyclic ketone solvent is poor, polyamic acid will not be effectively produced, and the solution will be gel-like or slurry-like with solid matter from unreacted raw materials or reactants settling. In addition, due to poor reactivity, the viscosity may not increase, and a polyamic acid solution with appropriate viscosity may not be obtained.

[0046] Thus, the reactivity of the diamine component and the tetracarboxylic dianhydride component in organic solvents containing cyclic ketone solvents, or in other words, the selection of each compound of the diamine component and tetracarboxylic dianhydride component to ensure a good polyaddition reaction, is crucial.

[0047] (Tetracarboxylic acid dianhydride component) The tetracarboxylic acid dianhydride component includes compounds having a diphenyl ether group in the molecule. A compound having a diphenyl ether group can also be described as a compound having an aromatic ring and an ether group as an aromatic ring linking group. Research by the inventors has shown that using such a tetracarboxylic acid dianhydride component allows for a good polyaddition reaction with the diamine component in a specific organic solvent, such as a cyclic ketone solvent, resulting in a polyamic acid solution with appropriate viscosity and excellent coating properties.

[0048] Specifically, as the tetracarboxylic dianhydride component, 4,4'-oxydiphthalic anhydride (ODPA), 3,4'-oxydiphthalic dianhydride, 3,3'-oxydiphthalic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA), 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride, etc. can be mentioned and can be preferably used.

[0049] Further, the tetracarboxylic dianhydride component preferably includes a compound having two or more diphenyl ether groups in the molecule. As shown in the examples described later, such a tetracarboxylic dianhydride component has particularly good reactivity in the polyaddition reaction in an organic solvent containing a cyclic ketone-based solvent.

[0050] Specifically, among the above-listed tetracarboxylic dianhydride components, it is preferable to contain one or more selected from 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA), 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, and 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride.

[0051] Among them, it is particularly preferable to use 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA).

[0052] The tetracarboxylic dianhydride component may be one of the above-mentioned compounds used alone, or multiple types may be used in any molar ratio.

[0053] Furthermore, tetracarboxylic dianhydrides may be used in combination with other compounds, as long as the reactive properties are not impaired. In this case, it is preferable that at least 80 mol%, and more preferably at least 90 mol%, of the total amount of tetracarboxylic dianhydride components be compounds having diphenyl ether groups in their molecules. Compounds having two or more diphenyl ether groups in their molecules are even more preferable.

[0054] Specifically, as the tetracarboxylic dianhydride component, the following compounds may be used in combination, to the extent that the reactive properties are not impaired: for example, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (i-BPDA), pyromellitic dianhydride (PMDA), merophanic dianhydride (MPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride, dicyclohexyl-3,4,3',4' -Tetracarboxylic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA), norbornane-2-spiro-2'-cyclopentanone-5'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid dianhydride (CpODA), 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride (6FDA), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarb Diphthalic acid anhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfontetracarboxylic acid dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1-ethylidene-4,4'-diphthalic acid dianhydride, 2,2-propyridene-4,4'-diphthalic acid dianhydride, 1,2-ethylene-4,4'-diphthalic acid dianhydride, 1,3-trimethylene-4,4'-diphthalic acid dianhydride, 1,4-tetramethylene-4,4'-diphthalic acid dianhydride, 1,5-pentamethylene-4,4'-diphthalic acid dianhydride Water, p-phenylenebis(trimellitate anhydride), thio-4,4'-diphthalic acid dianhydride, sulfonyl-4,4'-diphthalic acid dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracenetetracarboxylic acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride, bicyclohexyl-3,Examples include 3',9,9-bis(3,4-dicarboxyphenyl)fluorenodioanhydride (BPAF), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, spiro[11H-difluoro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetron (SFDA), (1,3-dioxoisobenzofuran-5-yl)1,3-dioxoisobenzofuran-5-carboxylate (8CI), bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl (TAHMBP), etc.

[0055] (Diamine component) The diamine component is not particularly limited. For example, m-phenylenediamine (m-PDA), p-phenylenediamine (p-PDA), 2,2-trifluorobenzidine, m-tolidine, 4,4'-diaminobenzanilide, 4-aminophenyl-4-aminobenzoate, (2-phenyl-4-aminophenyl)-4-aminobenzoate, 3,4'-diaminodiphenyl ether (3,4-ODA), 4,4'-diaminodiphenyl ether (4,4-ODA), 4,4'-diaminodiphenyl sulfone (4,4-DDS), 3,3'-diaminodiphenyl sulfone (3,3-DDS), 9,9'-(4-aminophenyl)fluorene, 9,9'-(4-amino-3-methylphenyl)fluorene, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2,2'-bis( Examples include trifluoromethoxy)benzidine, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (TPE-M), bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4-bis(4-aminophenoxy)biphenyl, 4,4-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4,4'-methylenebis(cyclohexanamine), etc.

[0056] Among these, the diamine component preferably contains one or more selected from m-phenylenediamine (m-PDA), 4,4'-diaminodiphenyl ether (4,4-ODA), m-tolidine, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (TPE-M), and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0057] The diamine component may be one of the above-mentioned compounds used alone, or multiple types may be used in any molar ratio.

[0058] From the viewpoint of preventing a decrease in the glass transition temperature (Tg) of polyimides obtained by imidizing polyamic acid, it is preferable that the total content of one or more diamine components selected from m-phenylenediamine and m-tolidine is 80 mol% or more relative to the total diamine components.

[0059] The diamine component may include other diamine compounds other than those mentioned above. Examples of other diamine compounds include aliphatic diamines such as 1,2-diaminoethane, 1,4-diaminobutane, tetramethylenediamine, and 1,10-diaminodecane; and siloxanediamines such as dimethyl(poly)siloxanediamine. Specific examples of dimethyl(poly)siloxanediamine products include PAM-E, KF-8010, and X-22-161A (all manufactured by Shin-Etsu Silicone Co., Ltd.).

[0060] If the diamine component includes an aliphatic diamine or a siloxane diamine, the content of the aliphatic diamine or siloxane diamine is preferably 30 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less, relative to the total diamine component. However, the total diamine component content is 100 mol%.

[0061] (Preferred combinations of tetracarboxylic dianhydride components and diamine components) With regard to each of the diamine and tetracarboxylic dianhydride components, among the compounds listed above, the following combinations are particularly preferred, as shown in the examples described later.

[0062] In other words, a combination in which the tetracarboxylic dianhydride component is 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid anhydride (BPADA), and the diamine component is one or more selected from m-phenylenediamine (m-PDA), 4,4'-diaminodiphenyl ether (4,4-ODA), m-tolidine, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (TPE-M), and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) is particularly preferred.

[0063] (Molar ratio of tetracarboxylic dianhydride to diamine component) The molecular weight of the resulting polyamic acid can be adjusted by adjusting the ratio of the total moles of the tetracarboxylic dianhydride component to the total moles of the diamine component. Specifically, the number of moles of each component is not particularly limited, but it is preferable that they be approximately equimolar. The molar ratio expressed as total amount of tetracarboxylic dianhydride component / total amount of diamine component is preferably in the range of greater than 0.9 and less than 1.2, more preferably between 0.95 and 1.1, and particularly preferably 1.

[0064] Thus, by ensuring that the total amount of tetracarboxylic dianhydride and the total amount of diamine components are approximately equimolar, it is possible to prevent a decrease in the molecular weight of the polyamic acid. Furthermore, it is possible to suppress the decrease in mechanical strength of the polyimide obtained by imidizing the polyamic acid. In addition, it prevents a decrease in the viscosity of the polyamic acid solution, resulting in even better coating properties. However, if the viscosity of the polyamic acid solution decreases, problems may occur, such as poor dispersibility of additives like inorganic fillers when dispersing them in the solution, leading to filler sedimentation.

[0065] (Synthesis of Polyamic Acids) The synthesis of polyamic acids by polyaddition of a diamine component and a tetracarboxylic dianhydride component is carried out in an organic solvent containing a cyclic ketone solvent. Furthermore, the polyaddition reaction is preferably carried out under an inert atmosphere such as argon or nitrogen.

[0066] Specifically, the polymerization reaction is carried out by dissolving the diamine component and the tetracarboxylic dianhydride component in an organic solvent containing a cyclic ketone solvent under an inert atmosphere and then mixing them. The order in which the diamine component and the tetracarboxylic dianhydride component are added is not particularly limited. For example, the diamine component can be dissolved or dispersed in a slurry in an organic solvent to form a diamine solution, and then the tetracarboxylic dianhydride component can be added to the diamine solution to carry out the reaction. In this case, the tetracarboxylic dianhydride component may be added to the diamine solution in a solid state, or it may be dissolved or dispersed in a slurry in an organic solvent containing a cyclic ketone solvent to form a tetracarboxylic dianhydride solution before being added.

[0067] The reaction temperature is not particularly limited. From the viewpoint of suppressing the decrease in molecular weight due to the depolymerization of the generated polyamic acid, the reaction temperature is preferably 80°C or lower. Furthermore, from the viewpoint of allowing the polymerization reaction to proceed appropriately, the reaction temperature is more preferably between 10°C and 50°C. The reaction time can be set as appropriate, for example, in the range of 10 minutes to 30 hours.

[0068] (Molecular weight of polyamic acid) The weight-average molecular weight of polyamic acid is not particularly limited, but is preferably in the range of 10,000 to 200,000, more preferably in the range of 30,000 to 180,000, and even more preferably in the range of 40,000 to 150,000. If the weight-average molecular weight is 10,000 or more, the mechanical strength of the polyimide obtained by imidizing the polyamic acid can be made sufficient. Furthermore, if the weight-average molecular weight of the polyamic acid is 200,000 or less, it exhibits sufficient solubility in organic solvents including cyclic ketone solvents, making it easier to obtain a coating film with a smooth surface and uniform film thickness on the substrate, as well as a polyimide film obtained by imidizing it.

[0069] Note that the molecular weight of the polyamic acid is the value obtained by gel filtration chromatography (GPC) on a polyethylene oxide basis.

[0070] [Additives] The polyamic acid solution may contain various additives, provided that they do not impair the solubility or storage stability of the polyamic acid in organic solvents. Examples of additives include inorganic fillers, imidation catalysts, dehydration catalysts, and surface modifiers. However, the additives are not limited to these.

[0071] Specifically, examples of inorganic fillers include inorganic salts such as aluminum oxide, silicon dioxide, calcium carbonate, and calcium phosphate. The shape of these inorganic fillers is not particularly limited and may be in powder, spherical, fibrous, or any other form.

[0072] Furthermore, tertiary amine compounds are preferably used as imidation catalysts, and heterocyclic tertiary amine compounds are particularly preferred among them. Examples include pyridine, 2,5-diethylpyridine, picoline, quinoline, isoquinoline, and 1,2-dimethylimidazole. Examples of dehydration catalysts include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride.

[0073] Furthermore, adding an imidizing agent or dehydration catalyst to a polyamic acid solution may cause the imidation reaction to proceed, resulting in gelation. Therefore, it is preferable to dissolve the imidizing agent or dehydration catalyst in an organic solvent and mix the resulting solution with the polyamic acid solution. Additionally, from the viewpoint of improving the storage stability of the polyamic acid solution, the aforementioned imidizing catalyst or dehydration catalyst may be added immediately before coating the polyamic acid solution onto the substrate.

[0074] Furthermore, surface modifiers can be added for purposes such as defoaming the solution or improving the surface smoothness of the formed polyimide film. The surface modifier is not particularly limited, but any agent that has appropriate compatibility with polyamic acid and other materials, and also possesses defoaming properties, is acceptable. Examples include acrylic compounds and silicon compounds.

[0075] [Stability of Polyamic Acid Solution] As described above, polyamic acids obtained by the polyaddition reaction of a diamine component with a specific tetracarboxylic dianhydride component exhibit excellent stability in organic solvents, including cyclic ketone solvents. In other words, polyamic acids have excellent solubility in organic solvents, including cyclic ketone solvents, and can suppress solidification and gelation over long periods of time.

[0076] Furthermore, the progression of imidization of polyamic acid in the polyamic acid solution can also be suppressed. Specifically, the imidization rate of polyamic acid is 30 mol% or less, preferably 10 mol% or less, relative to the total amount of structural units in the polyamic acid. Moreover, it is preferable that the imidization rate be even lower, and may be 1 mol% or less, or even 0 mol%. In this way, the imidization rate of polyamic acid in the polyamic acid solution is low, which suppresses viscosity increase, solidification, and gelation.

[0077] ≪2. Polyimides and Polyimide Films≫ By imidizing the polyamic acid contained in the polyamic acid solution described above, polyimides, which are imidized products, can be obtained. Specifically, the polyamic acid solution is coated onto the surface of a substrate, and the coated film is dried to volatilize the organic solvent contained in the polyamic acid solution. Subsequently, or simultaneously, the polyamic acid is imidized by dehydration and ring closure to obtain a polyimide (polyimide film).

[0078] The resulting polyimide has a structure derived from a tetracarboxylic dianhydride and a structure derived from a diamine. Therefore, the polyimide obtained from the polyamic acid solution according to this embodiment has an acid dianhydride residue having a diphenyl ether group in the molecule. Preferably, it has an acid dianhydride residue having two or more diphenyl ether groups in the molecule.

[0079] The application of the polyamic acid solution to the substrate is not particularly limited and can be carried out by known methods such as gravure coating, spin coating, screen printing, dip coating, bar coating, knife coating, roll coating, and die coating.

[0080] The substrate (support) to which the polyamic acid solution is coated is not particularly limited. Examples include metal substrates containing metal bodies or metal compounds such as copper plates, aluminum plates, and stainless steel plates, glass substrates, silicon wafers, polyethylene terephthalate, polycarbonate, polyacrylate, and other film substrates.

[0081] The organic solvent in the coating film obtained by coating the substrate can be removed by volatilization by heating the coating film. The heating temperature should be set according to the type of cyclic ketone solvent contained in the polyamic acid solution. Furthermore, heating can be carried out under air, under reduced pressure, or under an inert gas such as nitrogen.

[0082] Dehydration and ring closure of polyamic acid can be performed by heating the polyamic acid. For example, a coating film containing polyamic acid applied to the surface of a substrate is heat-treated in the range of 80°C to 200°C.

[0083] The heating time is preferably set appropriately according to the amount of polyamic acid to be dehydrated and cyclized and the heating temperature, and generally, it is preferable to heat for a period of 1 minute to 5 hours after the processing temperature reaches the maximum temperature. In addition, the imidation of dehydration cyclization proceeds along with the heating for the volatilization of the organic solvent mentioned above.

[0084] Furthermore, as described above, in order to shorten the heating time and achieve the desired properties, additives such as imidizing agents and dehydration catalysts may be added to the polyamic acid solution, and the coating film made from the polyamic acid solution with such additives added may be heat-treated to imide it.

[0085] As the imidating agent, tertiary amine compounds are preferred, and heterocyclic tertiary amines are more preferred. Specifically, examples include pyridine, 2,5-diethylpyridine, picoline, quinoline, isoquinoline, and 1,2-dimethylimidazole. Specifically, examples of dehydration catalysts include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride. The amount of imidating agent and dehydration catalyst added is preferably 0.05 to 5.0 times the molar equivalent of the imidating agent and more preferably 0.07 to 2.5 times the molar equivalent of the amide group of the polyamic acid. Furthermore, for the dehydration catalyst, it is preferably 0.5 to 10.0 times the molar equivalent of the amide group of the polyamic acid and more preferably 0.7 to 5.0 times the molar equivalent of the dehydration catalyst.

[0086] ≪3. Laminate with Polyimide Film and Method for Manufacturing the Same≫ As described above, a polyimide film, which is an imidized product, can be formed on the substrate by coating the surface of a substrate with a polyamic acid solution and performing heat treatment to carry out dehydration cyclization and imidization. This makes it possible to obtain a laminate having a substrate and a polyimide film on one or both sides of the substrate.

[0087] Therefore, a method for manufacturing a laminate can be defined as a method comprising the steps of: applying a polyamic acid solution to one or both sides of a substrate made of metal or the like to form a coating film containing polyamic acid; and heating the coating film to imide the polyamic acid to form a polyimide film.

[0088] The thickness of the polyimide film constituting the laminate can be appropriately set according to the application and desired function of the polyimide film, and is not particularly limited. For example, it can be about 1 μm to 50 μm, and is preferably about 5 μm to 30 μm.

[0089] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0090] [Preparation of Polyamic Acid Solution (Varnish)] A ketone solvent, which is an organic solvent, was placed in a separable flask and stirred under a nitrogen atmosphere. In Examples 1-10, 18-26 and Comparative Examples 1-13 shown in Table 1 below, cyclohexanone, a cyclic ketone solvent, was used. In Examples 11-17, 27-34 and Comparative Examples 14-16 shown in Table 2 below, cyclopentanone, a cyclic ketone solvent, was used. In Examples 35-37 and Comparative Example 29 shown in Table 4 below, 3-methylcyclohexanone, a cyclic ketone solvent, was used. In Comparative Examples 17-28 shown in Table 3 below, methyl ethyl ketone (MEK), a chain-like ketone solvent, was used.

[0091] To this, the tetracarboxylic dianhydride component and the diamine component were added in the ratios (mol%) shown in Tables 1 to 3, and the mixture was stirred under a nitrogen atmosphere for 5 to 10 hours to react and obtain a solution containing polyamic acid with a solid content of 18% by mass.

[0092] [Compounds used in the production of polyamic acid solutions and their abbreviations] (Organic solvents) Cyclic ketone solvents: Cyclohexanone (used in Examples 1-10, 18-26 and Comparative Examples 1-13 in Table 1), Cyclopentanone (used in Examples 11-17, 27-34 and Comparative Examples 14-16 in Table 2), 3-Methylcyclohexanone (used in Examples 35-37 and Comparative Example 29 in Table 4) Chain-like ketone solvent: Methyl ethyl ketone (MEK) (used in Comparative Examples 17-28 in Table 3)

[0093] (Tetracarboxylic acid dianhydride components) 'BPADA': 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride 'ODPA': 4,4'-oxydiphthalic anhydride 'BTDA': 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride 's-BPDA': 3,3',4,4'-biphenyltetracarboxylic acid dianhydride 'PMDA': pyromellitic anhydride Of the compounds used as tetracarboxylic acid dianhydride components listed above, BPADA and ODPA are compounds that have a diphenyl ether group in their molecule. In particular, BPADA is a compound that has two diphenyl ether groups in its molecule.

[0094] (Diamine components) 'm-PDA': m-phenylenediamine '4,4-ODA': 4,4'-diaminodiphenyl ether 'm-Tolidine': m-tolidine '3,3-DDS': 3,3'-diaminodiphenyl sulfone 'TFMB': 2,2'-bis(trifluoromethyl)benzidine 'TPE-R': 1,3-bis(4-aminophenoxy)benzene 'TPE-M': 1,3-bis(3-aminophenoxy)benzene 'BAPP': 2,2-bis[4-(4-aminophenoxy)phenyl]propane '1,10-diaminodecane' 'KF-8010': End-ended amino-modified silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd.)

[0095] [Evaluation] (Reactivity of polyamic acid synthesis in organic solvents) For the obtained polyamic acid solution, the molecular weight of the polyamic acid in the solution was measured, and if the molecular weight was 20,000 or more, it was evaluated as '◎' or '○', indicating that the tetracarboxylic dianhydride component and the diamine component had reacted well. Furthermore, if it was visually confirmed that the viscosity of the solution did not increase any further after 1 hour from the mixing of the tetracarboxylic dianhydride component and the diamine component (i.e., the reaction was very fast and reached a near-steady state in 1 hour), it was evaluated as '◎', and if it took more than 1 hour from the start of mixing to reach a steady state (i.e., the reaction was fast), it was evaluated as '○'. The molecular weight of the polyamic acid was measured using gel filtration chromatography (GPC) and is the weight-average molecular weight (Mw) in terms of polyethylene oxide.

[0096] On the other hand, if no increase in viscosity was observed, or if gelation occurred while some powder remained, visual inspection indicated that the tetracarboxylic dianhydride component and diamine component remained intact, and the molecular weight of the polyamic acid was considered to be less than 20,000, resulting in a reactivity rating of '×'.

[0097] (Molecular Weight of Polyamic Acid) In addition, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the obtained polyamic acid are also shown in the evaluation column of each table. The molecular weight of the polyamic acid is the polyethylene oxide equivalent value measured using gel filtration chromatography (GPC), as described above. In Tables 1 to 3, the notation "-" in the molecular weight measurement results indicates that it was not measured.

[0098] [Results] Tables 1 to 4 below show the raw material monomers used and the results regarding the reactivity of polyamic acid synthesis in organic solvents. As mentioned above, Table 1 shows the test results using cyclohexanone, a cyclic ketone solvent, as the organic solvent; Table 2 shows the test results using cyclopentanone, a cyclic ketone solvent, as the organic solvent; Table 3 shows the test results using methyl ethyl ketone, a chain-like ketone solvent, as the organic solvent; and Table 4 shows the test results using 3-methylcyclohexanone, a cyclic ketone solvent, as the organic solvent.

[0099]

[0100]

[0101]

[0102]

[0103] The results shown in Tables 1-4 indicate that the reactivity of the polyaddition reaction between the tetracarboxylic dianhydride component and the diamine component varies significantly depending on the type of organic solvent used in the synthesis of polyamic acids. Furthermore, even when using the same organic solvent, the reactivity of the polyaddition reaction differs depending on the specific compound species, i.e., the combination, of the tetracarboxylic dianhydride component and the diamine component.

[0104] As can be seen from the results shown in Tables 1, 2, and 4, when a cyclic ketone solvent was used as the organic solvent, the tetracarboxylic dianhydride component, being a compound with a diphenyl ether group in its molecule, reacted well with the diamine component through polyaddition, resulting in a varnish with appropriate viscosity. Table 3 shows that even if the tetracarboxylic dianhydride component was a compound with a diphenyl ether group in its molecule, similar to the test examples in Tables 1 and 2, using a different organic solvent (MEK, a linear ketone solvent, in the test example in Table 3) did not result in a good polyaddition reaction, leading to poor quality, such as gelation of the varnish.

[0105] Furthermore, the results in Tables 1, 2, and 4 show that, in particular, when the tetracarboxylic dianhydride component is a compound having two or more diphenyl ether groups in its molecule, the reactivity is further improved, and a varnish with the desired appropriate viscosity can be obtained.

Claims

1. A polyamic acid composition comprising an organic solvent and a polyamic acid which is a polyaddition reaction product of a diamine component and a tetracarboxylic dianhydride component in the organic solvent, wherein the organic solvent comprises a cyclic ketone solvent and the tetracarboxylic dianhydride component comprises a compound having a diphenyl ether group in its molecule.

2. The polyamic acid composition according to claim 1, wherein the content of the compound having a diphenyl ether group in the molecule is 80 mol% or more relative to the total tetracarboxylic dianhydride component.

3. The polyamic acid composition according to claim 1, wherein the tetracarboxylic dianhydride component comprises a compound having two or more diphenyl ether groups in its molecule.

4. The polyamic acid composition according to claim 3, wherein the content of a compound having two or more diphenyl ether groups in the molecule is 80 mol% or more with respect to the total tetracarboxylic dianhydride component.

5. The polyamic acid composition according to claim 1, wherein the compound having a diphenyl ether group in the molecule comprises one or more selected from 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride and 4,4'-oxydiphthalic anhydride.

6. The polyamic acid composition according to claim 1, wherein the diamine component comprises one or more selected from m-phenylenediamine and m-tolidine.

7. The polyamic acid composition according to claim 6, wherein the total content of one or more diamine components selected from m-phenylenediamine and m-tolidine is 80 mol% or more of the total diamine components.

8. The polyamic acid composition according to claim 1, wherein the diamine component comprises an aliphatic diamine or a siloxanediamine, the content of the aliphatic diamine or siloxanediamine is 30 mol% or less relative to the total diamine component, provided that the total diamine component content is 100 mol%.

9. The polyamic acid composition according to claim 1, wherein the diamine component comprises an aliphatic diamine or a siloxanediamine, the content of the aliphatic diamine or siloxanediamine being 10 mol% or less relative to the total diamine component, provided that the total diamine component content is 100 mol%.

10. The polyamic acid composition according to claim 1, wherein the molar ratio expressed as the total amount of the tetracarboxylic dianhydride component / the total amount of the diamine component is greater than 0.9 and less than 1.

2.

11. The polyamic acid composition according to claim 1, wherein the cyclic ketone solvent is contained in an amount of 70% by mass or more relative to the total amount of the organic solvent.

12. The polyamic acid composition according to claim 1, wherein the cyclic ketone solvent comprises one or more selected from cyclohexanone and cyclopentanone.

13. A method for producing a polyamic acid composition comprising a polyamic acid obtained by polyaddition reaction of a diamine component and a tetracarboxylic dianhydride component in an organic solvent, comprising mixing a diamine component and a tetracarboxylic dianhydride component containing a compound having a diphenyl ether group in its molecule in an organic solvent containing a cyclic ketone solvent.

14. A polyimide which is an imide of a polyamic acid contained in the polyamic acid composition according to any one of claims 1 to 12.

15. A polyimide film comprising the polyimide described in claim 14.

16. A laminate comprising a substrate and a polyimide film according to claim 15 formed on one or both sides of the substrate.

17. A method for manufacturing a laminate comprising a substrate and a polyimide film, comprising the steps of: coating one or both sides of the substrate with the polyamic acid composition according to any one of claims 1 to 12 to form a coating film containing the polyamic acid; and heating the coating film to imide the polyamic acid to form a polyimide film.

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