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 includes a cyclic ketone-based solvent, and the diamine component includes a compound having one or more ether group, sulfone group, or trifluoromethyl group in each molecule. The diamine component more preferably includes an aromatic diamine compound that has an ether group and has three or more aromatic rings in each molecule. The tetracarboxylic acid dianhydride component more preferably includes a compound that has an aromatic ring and an ether group or ketone group as an aromatic ring linking group.

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 cyclization. Also, in the production of a laminate including a polyimide film which is an electronic component material, etc., a method is known in which a polyamic acid solution is applied to at least one side of a substrate (support) made of metal or the like constituting the laminate to form a coated film, and after volatilizing and removing the organic solvent, imidization is performed to form a polyimide film.

[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 a technical problem of providing 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 diamine component containing a compound having a specific structure in a cyclic ketone solvent, a polyaddition reaction proceeds smoothly with the tetracarboxylic dianhydride 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 diamine component comprises a compound having one or more ether groups, sulfone groups, and trifluoromethyl groups 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 a compound having one or more of an ether group, a sulfone group, and a trifluoromethyl group in the molecule is 80 mol% or more with respect to the total diamine component.

[0015] (3) The third invention of the present invention is a polyamic acid composition in which, in the first or second invention, the content of a compound having one or more of an ether group, a sulfone group, and a trifluoromethyl group in the molecule is 90 mol% or more with respect to the total diamine component.

[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 diamine component comprises an aromatic diamine compound having an ether group in the molecule and having three or more aromatic rings.

[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 content of an aromatic diamine compound having an ether group in the molecule and having three or more aromatic rings is 80 mol% or more with respect to the total diamine components.

[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 tetracarboxylic dianhydride component comprises a compound having an aromatic ring and having an ether group or a ketone group as an aromatic ring linking group.

[0019] (7) The seventh invention of the present invention is the polyamic acid composition according to claim 5, wherein, in any of the first to sixth inventions, the content of a compound having an aromatic ring and having an ether group or a ketone group as an aromatic ring linking group is 80 mol% or more with respect to the total tetracarboxylic dianhydride component.

[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 compound having the aromatic ring and having an ether group or a ketone group as an aromatic ring linking group comprises one or more selected from 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride.

[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 one or more selected from 1,3-bis(3-aminophenoxy)benzene (TPE-M) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and the tetracarboxylic dianhydride component comprises one or more selected from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA).

[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 diamine component comprises an aliphatic diamine or a siloxane diamine, the content of the aliphatic diamine is 30 mol% or less relative to the total diamine component, provided that the content of the total diamine component is 100 mol%.

[0023] (11) The eleventh invention of the present invention is a polyamic acid composition in which, in any of the first to tenth inventions, the diamine component comprises an aliphatic diamine or a siloxane diamine, the content of the aliphatic diamine is 10 mol% or less relative to the total diamine component, provided that the content of the total diamine component is 100 mol%.

[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 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.

[0025] (13) The thirteenth invention of the present invention is a polyamic acid composition in which, in any of the first to twelfth inventions, the cyclic ketone solvent is contained in an amount of 90% by mass or more relative to the total amount of the organic solvent. (14) The fourteenth invention of the present invention is a polyamic acid composition in which, in any of the first to thirteenth inventions, the cyclic ketone solvent comprises one or more selected from cyclohexanone, cyclopentanone, 3-methylcyclohexanone, 4-methylcyclohexanone, and 4-ethylcyclohexanone.

[0026] (15) The fifteenth 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 method involves mixing a diamine component having one or more of an ether group, a sulfone group, and a trifluoromethyl group in its molecule with a tetracarboxylic dianhydride component in an organic solvent containing a cyclic ketone solvent.

[0027] (16) The sixteenth invention of the present invention is a polyimide, which is an imide of a polyamic acid contained in a polyamic acid composition according to any one of the first to fourteenth inventions.

[0028] (17) The seventeenth invention of the present invention is a polyimide film comprising the polyimide according to the sixteenth invention.

[0029] (18) The eighteenth invention of the present invention is a laminate having a substrate and a polyimide film according to the seventeenth invention formed on one or both sides of the substrate.

[0030] (19) The 19th 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 of the first to 14th 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.

[0031] 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.

[0032] 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.

[0033] ≪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.

[0034] 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.

[0035] Specifically, the polyamic acid solution according to this embodiment contains a cyclic ketone solvent as the organic solvent. Furthermore, the diamine component is characterized by containing a compound having one or more of the following in its molecule: an ether group, a sulfone group, and a trifluoromethyl group.

[0036] 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.

[0037] As a result of the inventors' research, it has been found that in organic solvents containing cyclic ketone solvents, a polyamic acid solution with appropriate viscosity can be obtained by using a compound having one or more ether groups, sulfone groups, and trifluoromethyl groups in its molecule as the diamine component, which reacts well with the tetracarboxylic dianhydride component. Such a polyamic acid solution exhibits excellent solubility of the polyamic acid in its organic solvent and also has excellent coating properties for substrates.

[0038] [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.

[0039] Cyclic ketone solvents are among the safest organic solvents and exhibit excellent solubility of the resulting polyamic acid.

[0040] 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.

[0041] The cyclic ketone solvent is not particularly limited, but examples include cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, 3-methylcyclohexanone, 4-methylcyclohexanone, and 4-ethylcyclohexanone, which are preferably used. In particular, from the viewpoint of polyamic acid solubility, it is preferable to include one or more selected from cyclopentanone, cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, and 4-ethylcyclohexanone.

[0042] Furthermore, the organic solvent may be a mixed solvent containing other types of organic solvents, as long as it mainly contains the cyclic ketone solvent described above and does not impair the reactivity of the selected raw material monomer. The main component refers to a component that is present in a proportion of 51% by mass or more of the total amount of the organic solvent. In particular, the cyclic ketone solvent is preferably present in a proportion of 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more of the total amount of the organic solvent. It is especially preferable that the entire amount of the organic solvent be a cyclic ketone solvent.

[0043] Furthermore, it is preferable that the organic solvent does not contain amide-based solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DFM), N-methylpyrrolidone (NMP), or N-butyl-2-pyrrolidone (NBP).

[0044] [Polyamic Acid] The polyamic acid contains structural units derived from a diamine component and a tetracarboxylic dianhydride. Specifically, the polyamic acid is a reaction product obtained by the polyaddition reaction of a diamine component, which is a raw material monomer, and a tetracarboxylic dianhydride component. The polyamic acid is a precursor of polyimide, and polyimide is obtained by dehydrative cyclization (imidization) of the polyamic acid.

[0045] The polyamic acid contained in the polyamic acid solution according to this embodiment is obtained by the 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 the polyamic acid is dissolved in the organic solvent as it is.

[0046] If the diamine component and the tetracarboxylic dianhydride component undergo a good polyaddition reaction in an organic solvent containing a cyclic ketone-based solvent, polyamic acid with an appropriate molecular weight is generated in the organic solvent, and a polyamic acid solution with an appropriate viscosity in which the polyamic acid is uniformly dispersed is obtained. Such a polyamic acid solution has excellent coatability on a substrate (support) made of metal or the like and can form a good polyimide film. On the other hand, if the polyaddition reaction between the diamine component and the tetracarboxylic dianhydride component is poor in an organic solvent containing a cyclic ketone-based solvent, polyamic acid is not effectively generated, and a slurry state in which a gel or solids derived from unreacted raw materials or reaction products settle is formed. Also, due to poor reactivity, it may not be possible to obtain a polyamic acid solution having an appropriate viscosity without an increase in viscosity.

[0047] Thus, the reactivity of the diamine component and the tetracarboxylic dianhydride component in an organic solvent containing a cyclic ketone-based solvent, in other words, the selection of each compound of the diamine component and the tetracarboxylic dianhydride component for a good polyaddition reaction, becomes important.

[0048] (Diamine component) The diamine component includes a compound having at least one of an ether group, a sulfone group, and a trifluoromethyl group in the molecule. As a result of research by the present inventor, by using such a diamine component, in a cyclic ketone solvent which is a specific organic solvent, the polyaddition reaction with a tetracarboxylic dianhydride component proceeds well, and it has been found that a polyamic acid solution having an appropriate viscosity and excellent coating properties is obtained.

[0049] Specifically, as the diamine component, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2,2'-bis(trifluoromethoxy)benzidine, 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), 3,3'-diaminodiphenyl sulfone (3,3'-DDS), 4,4'-diaminodiphenyl sulfone (4,4'-DDS), 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene (TPR-E), 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, etc. can be mentioned, and they can be preferably used.

[0050] Further, the diamine component preferably includes an aromatic diamine compound having an ether group in the molecule and having three or more aromatic rings. As shown in the examples described later, such a diamine component has particularly good reactivity in the polyaddition reaction in an organic solvent containing a cyclic ketone solvent.

[0051] Specifically, it is preferable that the above-mentioned diamine compounds include one or more selected from 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (TPE-M), 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), and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

[0052] In particular, it is preferable to include one or more selected from 1,3-bis(3-aminophenoxy)benzene (TPE-M) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP).

[0053] The diamine component may be one of the above-mentioned compounds used alone, or multiple types may be used in any molar ratio. When multiple types are combined, it is preferable that 80 mol% or more, more preferably 90 mol% or more of the total amount of the diamine component is a compound having one or more of an ether group, a sulfone group, and a trifluoromethyl group in its molecule, or an aromatic diamine compound having an ether group in its molecule and three or more aromatic rings.

[0054] From the viewpoint of preventing a decrease in the glass transition temperature (Tg) of polyimides obtained by imidizing polyamic acids, it is preferable that the diamine component consists only of compounds having one or more of the following in its molecule: an ether group, a sulfone group, and a trifluoromethyl group.

[0055] The diamine component may include other diamine compounds other than those having one or more ether groups, sulfone groups, and trifluoromethyl groups in its molecule. 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 products of dimethyl(poly)siloxanediamine include PAM-E, KF-8010, and X-22-161A (all manufactured by Shin-Etsu Silicone Co., Ltd.).

[0056] 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%.

[0057] (Tetracarboxylic acid dianhydride component) The tetracarboxylic acid dianhydride component is not particularly limited. For example, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA), pyromellitic acid dianhydride (PMDA), 4,4'-oxydiphthalic acid anhydride (ODPA), 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid anhydride (BPADA), 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-dicarboxylic acid anhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic acid dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1-ethylidene-4 ,4'-diphthalic anhydride, 2,2-propyridene-4,4'-diphthalic anhydride, 1,2-ethylene-4,4'-diphthalic anhydride, 1,3-trimethylene-4,4'-diphthalic anhydride, 1,4-tetramethylene-4,4'-diphthalic anhydride, 1,5-pentamethylene-4,4'-diphthalic anhydride, 4,4'-oxydiphthalic anhydride, p-phenylenebis(trimellitate anhydride), thio-4,4'-diphthalic anhydride, sulfonyl-4,4'-diphthalic anhydride, 1,3-bis(3,4-diphthalic anhydride) Boxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]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, 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-3,3',9,9-bis(3,4-dicarboxyphenyl)fluorenediacid anhydride (BP Examples include AF), 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.

[0058] Among these, the tetracarboxylic dianhydride component is preferably a compound having an aromatic ring and an ether group or a ketone group as the aromatic ring linking group. As will be shown in the examples described later, such tetracarboxylic dianhydride components exhibit particularly good reactivity in polyaddition reactions with the diamine components mentioned above in organic solvents containing cyclic ketone solvents.

[0059] Furthermore, it is more preferable that the tetracarboxylic dianhydride component includes one or more selected from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), and 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride (BPADA).

[0060] The tetracarboxylic dianhydride component may be used alone as one of the above-mentioned compounds, or multiple types may be used in any molar ratio. When multiple types are combined, preferably 80 mol% or more, more preferably 90 mol or more, of the total amount of tetracarboxylic dianhydride components are compounds having an aromatic ring and having an ether group or a ketone group as the aromatic ring linking group.

[0061] (Preferred combinations of diamine and acid dianhydride components) With regard to each of the diamine and acid dianhydride compounds, 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 diamine component is one or more selected from 1,3-bis(3-aminophenoxy)benzene (TPE-M) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and the tetracarboxylic dianhydride component is one or more selected from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic anhydride (ODPA), and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA) is particularly preferred.

[0063] (Molar ratio of diamine component to tetracarboxylic dianhydride) The molecular weight of the resulting polyamic acid can be adjusted by adjusting the ratio of the total number of moles of the diamine component to the total number of moles of the tetracarboxylic dianhydride 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 molar amount of the diamine component and the total molar amount of the tetracarboxylic dianhydride 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 specific diamine component with a 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 diamine and a structure derived from a tetracarboxylic dianhydride. Therefore, the polyimide obtained from the polyamic acid solution according to this embodiment has a diamine residue having one or more of an ether group, a sulfone group, and a trifluoromethyl group in its molecule. Preferably, it has an aromatic diamine residue having an ether group and three or more aromatic rings in its molecule. Preferably, it has an acid dianhydride residue having an aromatic ring and whose aromatic ring linking group is an ether group or a ketone group.

[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 1-20, 40-47 and Comparative Examples 1-10 shown in Table 1 below, cyclohexanone, a cyclic ketone solvent, was used as the organic solvent. In Examples 21-29, 48-54 and Comparative Example 11 shown in Table 2 below, cyclopentanone, a cyclic ketone solvent, was used. In Examples 30-34 and 55-60 shown in Table 3 below, 3-methylcyclohexanone, a cyclic ketone solvent, was used. In Examples 35-37 and Comparative Example 12 shown in Table 4 below, 4-methylcyclohexanone, a cyclic ketone solvent, was used. In Examples 38-39 and Comparative Example 13 shown in Table 5 below, 4-ethylcyclohexanone, a cyclic ketone solvent, was used. On the other hand, in Comparative Examples 14 to 24 and Reference Examples 1 to 4 shown in Table 6 below, methyl ethyl ketone (MEK), a chain-like ketone solvent, was used as the organic solvent.

[0091] The diamine component and the tetracarboxylic dianhydride component were added in the ratios (mol%) shown in Tables 1 to 6, 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 1-20, 40-47 and Comparative Examples 1-10 in Table 1) Cyclopentanone (used in Examples 21-29, 48-54 and Comparative Example 11 in Table 2) 3-Methylcyclohexanone (used in Examples 30-34 and 55-60 in Table 3) 4-Methylcyclohexanone (used in Examples 35-37 and Comparative Example 12 in Table 4) 4-Ethylcyclohexanone (used in Examples 38-39 and Comparative Example 13 in Table 5) Chain-like ketone solvent: Methyl ethyl ketone (MEK) (used in Comparative Examples 14-24 and Reference Examples 1-4 in Table 6)

[0093] (Diamine components) 'BAPP': 2,2-bis[4-(4-aminophenoxy)phenyl]propane 'TPE-M': 1,3-bis(3-aminophenoxy)benzene 'TPE-R': 1,3-bis(4-aminophenoxy)benzene 'TFMB': 2,2'-bis(trifluoromethyl)benzidine '3,3-DDS': 3,3'-diaminodiphenylsulfone '4,4-ODA': 4,4'-diaminodiphenyl ether 'm-PDA': m-phenylenediamine 'PDA': p-phenylenediamine 'm-Tolidine': m-Tolidine '1,10-diaminodecane' 'KF-8010': End-ended amino-modified silicone oil (manufactured by Shin-Etsu Silicone Co., Ltd.) Of the compounds used as diamine components mentioned above, BAPP, TPE-M, TPE-R, TFMB, 3,3-DDS, and 4,4-ODA are compounds having one or more ether groups, sulfone groups, and trifluoromethyl groups in their molecules. Furthermore, BAPP, TPE-M, and TPE-R are aromatic diamine compounds having an ether group in their molecules and having three or more aromatic rings. Note that 1,10-diaminodecane is an aliphatic diamine, and KF-8010 is a siloxanediamine.

[0094] (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 'a-BPDA': 2,3,3',4'-biphenyltetracarboxylic acid dianhydride 's-BPDA': 3,3',4,4'-biphenyltetracarboxylic acid dianhydride 'PMDA': pyromellitic anhydride

[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 diamine component and the tetracarboxylic dianhydride 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 diamine component and tetracarboxylic dianhydride 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 in 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 6, the notation "-" in the molecular weight measurement results indicates that it was not measured.

[0098] [Results] Tables 1 to 6 below show the raw material monomers used and the results regarding the reactivity of polyamic acid synthesis in organic solvents. As mentioned above, the results for Examples 1 to 20, 40 to 47 and Comparative Examples 1 to 10 were obtained using cyclohexanone, a cyclic ketone solvent, as the organic solvent, while the results for Examples 21 to 29, 48 to 54 and Comparative Example 11 were obtained using cyclopentanone, a cyclic ketone solvent. Furthermore, the results for Examples 30 to 34 and 55 to 60 were obtained using 3-methylcyclohexanone, a cyclic ketone solvent, while the results for Examples 35 to 37 and Comparative Example 12 were obtained using 4-methylcyclohexanone, a cyclic ketone solvent, and the results for Examples 38 to 39 and Comparative Example 13 were obtained using 4-ethylcyclohexanone, a cyclic ketone solvent. On the other hand, the results for Comparative Examples 14 to 24 and Reference Examples 1 to 4 were obtained using methyl ethyl ketone, a chain-like ketone solvent, as the organic solvent.

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105] The results shown in Tables 1-6 indicate that the reactivity of the polyaddition reaction between the diamine component and the tetracarboxylic dianhydride 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., combination, of the diamine component and the tetracarboxylic dianhydride component.

[0106] As can be seen from the results shown in Tables 1 to 5, when a cyclic ketone solvent was used as the organic solvent, the diamine component, if it contained one or more ether groups, sulfone groups, and trifluoromethyl groups in its molecule, reacted well with the tetracarboxylic dianhydride component through polyaddition, resulting in a varnish with appropriate viscosity. However, as can be seen from Table 6, even when the diamine component contained one or more ether groups, sulfone groups, and trifluoromethyl groups in its molecule, similar to the test examples in Tables 1 to 5, if a different organic solvent was used (MEK, a linear ketone solvent, in the test example in Table 6), a good polyaddition reaction did not occur, resulting in poor quality such as the varnish gelling or failing to increase in viscosity.

[0107] Furthermore, the results shown in Tables 1-5 indicate that, in particular, when the diamine component is an aromatic diamine compound having an ether group in the molecule and three or more aromatic rings, 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 diamine component comprises a compound having one or more of an ether group, a sulfone group, and a trifluoromethyl group in its molecule.

2. The polyamic acid composition according to claim 1, wherein the content of a compound having one or more of an ether group, a sulfone group, and a trifluoromethyl group in the molecule is 80 mol% or more with respect to the total diamine components.

3. The polyamic acid composition according to claim 1, wherein the content of a compound having one or more of an ether group, a sulfone group, and a trifluoromethyl group in the molecule is 90 mol% or more with respect to the total diamine components.

4. The polyamic acid composition according to claim 1, wherein the diamine component comprises an aromatic diamine compound having an ether group in the molecule and having three or more aromatic rings.

5. The polyamic acid composition according to claim 4, wherein the content of an aromatic diamine compound having an ether group in the molecule and having three or more aromatic rings is 80 mol% or more of the total diamine components.

6. The polyamic acid composition according to claim 4, wherein the tetracarboxylic dianhydride component comprises a compound having an aromatic ring and having an ether group or a ketone group as an aromatic ring linking group.

7. The polyamic acid composition according to claim 6, wherein the content of a compound having an aromatic ring and having an ether group or a ketone group as an aromatic ring linking group is 80 mol% or more with respect to the total tetracarboxylic dianhydride component.

8. The polyamic acid composition according to claim 6, wherein the compound having the aromatic ring and having an ether group or a ketone group as an aromatic ring linking group comprises one or more selected from 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride.

9. The polyamic acid composition according to claim 1, wherein the diamine component comprises one or more selected from 1,3-bis(3-aminophenoxy)benzene and 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and the tetracarboxylic dianhydride component comprises one or more selected from 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride.

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

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

12. 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.

13. The polyamic acid composition according to claim 1, wherein the cyclic ketone solvent is contained in an amount of 90% by mass or more relative to the total amount of the organic solvent.

14. The polyamic acid composition according to claim 1, wherein the cyclic ketone solvent comprises one or more selected from cyclohexanone, cyclopentanone, 3-methylcyclohexanone, 4-methylcyclohexanone, and 4-ethylcyclohexanone.

15. 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 having one or more ether groups, sulfone groups, and trifluoromethyl groups in its molecule with a tetracarboxylic dianhydride component in an organic solvent containing a cyclic ketone solvent.

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

17. A polyimide film comprising the polyimide described in claim 16.

18. A laminate comprising a substrate and a polyimide film according to claim 17 formed on one or both sides of the substrate.

19. 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 14 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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