Polyamic acid, polyimide, resin film, and metal-clad laminate

Abstract

This invention provides polyimides that contribute to carbon neutrality, circular economy, and sustainable product development, while also offering polyamic acids that provide both heat resistance and adhesive properties, as well as resin films and metal-clad laminates using the same. [Solution] A polyamic acid containing an acid anhydride residue derived from an acid anhydride component and a diamine residue derived from a diamine component, The total amount of acid anhydride residues contains 10 to 90 mol% of the acid anhydride residue (A1) derived from the acid anhydride component represented by formula (A1), The total diamine residues contain 10 to 100 mol% of diamine residue (B1) derived from one or more diamine components selected from the group consisting of formulas (B1-1) to (B1-3), Polyamic acids and polyimides characterized by containing a total of 20 to 150 mol% of the acid anhydride residue (A1) and diamine residue (B1) relative to the sum of all acid anhydride residues and all diamine residues.

Description

Technical Field

[0001] The present invention relates to a polyamic acid, a polyimide obtained by imidizing the polyamic acid, a resin film using the polyimide, and a metal-clad laminate.

Background Art

[0002] In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, there has been an increasing demand for flexible printed circuit boards (FPCs) that are thin, lightweight, flexible, and have excellent durability even when repeatedly bent. Since FPCs enable three-dimensional and high-density mounting even in limited space, their applications are expanding, for example, to wirings in movable parts of electronic devices such as HDDs, DVDs, and smartphones, and to components such as cables and connectors. Many FPCs are manufactured by forming a circuit on a metal layer of a metal-clad laminate in which a metal layer using a metal foil or the like and an insulating resin substrate (insulating resin layer) are laminated.

[0003] Here, polyimide films are widely used in various fields because they have excellent properties such as heat resistance, cold resistance, chemical resistance, electrical insulation, and mechanical strength. Utilizing the characteristics of particularly excellent heat resistance and high rigidity, they are widely used as the insulating resin layer of FPCs. In particular, it is expected that electronic devices will become more highly functional and miniaturized in the future. Therefore, for example, in FPCs, the need to use them in a multilayered state is considered to increase, and in response to the thinning of the casings of electronic devices such as mobile phones and smartphones, there is an increasing tendency for the circuit board itself to be thinner. Therefore, in order to suppress wrinkles during pattern processing and conveyance for the thinning of the insulating resin layer accompanying the thinning of the circuit board itself, a higher mechanical strength, that is, a higher elastic modulus, of the polyimide film used for the insulating resin layer is required.

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

[0005] In response to this background and recent demands regarding polyimides, Patent Document 1 proposes a polyimide material that has excellent heat resistance, optical properties, and dielectric properties while increasing its bio-based nature by using tetracarboxylic dianhydrides synthesized from dianhydrohexitol such as isosorbide and isomannide, which are bio-based raw materials, and trimellitic anhydrides. However, the polyimide described in Patent Document 1 had room for further improvement in properties such as the aforementioned heat resistance and mechanical strength. Furthermore, in applications such as FPCs, adhesion between the metal layer and the insulating resin layer is necessary, but Patent Document 1 did not consider or even suggest such adhesion. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2023 / 027031 [Patent Document 2] Japanese Patent Publication No. 2023-163314 [Patent Document 3] Chinese Patent Application Publication No. 116425976 Specification [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, as a result of diligent research by the inventors of this application, they discovered that in developing a polyimide preferably used as an insulating resin layer constituting an FPC, by using specific compounds as the acid anhydride component and the diamine component constituting the polyimide, and further adjusting their amounts to a predetermined range, it is possible to achieve both heat resistance and adhesion while using bio-based raw materials, thus completing the present invention.

[0008] Therefore, an object of the present invention is to provide a polyamic acid that provides a polyimide capable of both heat resistance and adhesiveness. Another object of the present invention is to provide a resin film and a metal-clad laminate using such a polyimide. Furthermore, another object of the present invention is to provide a polyamic acid, polyimide, resin film, and metal-clad laminate that can contribute to carbon neutrality, a circular economy, and sustainable product development.

[0009] Furthermore, regarding tetracarboxylic dianhydrides, which are raw materials for polyimides, other prior art besides the aforementioned Patent Document 1 has proposed polyimides using specific tetracarboxylic dianhydrides, similar to those used in Patent Document 1 (Patent Documents 2 and 3). However, the polyimide proposed in Patent Document 2 is an improvement over the polyimide using dimer acid type diamines disclosed in earlier technologies, which had problems with elongation and elastic modulus. However, since Patent Document 2 also requires the use of dimer amine, it has problems with quality stability and its heat resistance was not sufficient. On the other hand, the polyimide proposed in Patent Document 3 is shown to have high transparency and heat resistance by using semi-aromatic dianhydride monomers having ester groups and isosorbide structures as raw materials. However, there is room for further improvement in the heat resistance and mechanical strength, and adhesion has not been considered, nor has it been suggested. [Means for solving the problem]

[0010] In other words, the present invention is as follows: [1] A polyamic acid containing an acid anhydride residue derived from an acid anhydride component and a diamine residue derived from a diamine component, The total amount of acid anhydride residues contains 10 to 90 mol% of the acid anhydride residue (A1) derived from the acid anhydride component represented by the following formula (A1), The total diamine residues contain 10 to 100 mol% of a diamine residue (B1) derived from one or more diamine components selected from the group consisting of the following formulas (B1-1) to (B1-3), A polyamic acid characterized by containing a total of 20 to 150 mol% of the acid anhydride residue (A1) and diamine residue (B1) relative to the sum of all acid anhydride residues and all diamine residues. [ka] [ka] [In formulas (B1-1) to (B1-3), R1 independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, n1 independently represents an integer from 0 to 4, X independently represents -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -CO-, -SO2-, -NH-, or -(CH2)m-, and m represents an integer from 1 to 3.] [2] The polyamic acid according to [1], characterized in that it contains 10 to 90 mol% of an acid anhydride residue (A2) derived from an acid anhydride component represented by the following formula (A2) relative to the total acid anhydride residues. [ka] [In formula (A2), A independently represents one of the groups selected from the following formulas (A2-1) to (A2-4).] [ka] [In formulas (A2-1) to (A2-4), Y independently represents a single bond, -CO-, -O-, -S-, -SO2-, -COO- or -NHCO-; R2 independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group or a trifluoromethyl group; and n2 independently represents an integer of 0 to 4.] [3] The polyamic acid according to [1], characterized in that it contains 10 to 90 mol% of a diamine residue (B2) derived from a diamine component represented by the following formula (B2) with respect to all diamine residues. [Chemical formula] [In formula (B2), Z independently represents a single bond, -COO- or -NHCO-; R3 independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group or a trifluoromethyl group; n3 independently represents an integer of 0 to 4; and a represents an integer of 0 to 2.] [4] The polyamic acid according to [1], characterized in that it contains 10 to 50 mol% of an acid anhydride residue (A1) derived from an acid anhydride component represented by the above formula (A1) with respect to all acid anhydride residues. [5] The polyamic acid according to [1], characterized in that the diamine residue (B1) is a diamine residue derived from any one or two or more diamine components selected from the group consisting of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 4,4'-diaminodiphenyl ether (4,4'-DAPE), 1,4-bis(4-aminophenoxy)benzene (TPE-Q) and bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS). [6] A polyimide obtained by imidizing the polyamic acid according to any one of [1] to [5]. [7] A resin film containing a polyimide obtained by imidizing the polyamic acid according to any one of [1] to [5]. [8] The resin film according to [7], characterized in that the glass transition temperature is 250 °C or higher. [9] The resin film according to [7], characterized in that the glass transition temperature is 285 °C or higher.

[10] The resin film according to [7], characterized in that the 5% weight loss temperature (Td5) is 400 °C or higher.

[11] A metal-clad laminate comprising an insulating resin layer composed of a single layer or a plurality of layers, and a metal layer laminated on at least one surface of the insulating resin layer, The metal-clad laminate, characterized in that the insulating resin layer contains the resin film according to [7].

[12] The metal-clad laminate according to

[11] , characterized in that the 180° peel strength between the metal layer and the insulating resin layer is 0.8 kN / m or higher.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a polyimide having both heat resistance and adhesiveness, a resin film using the same, and a metal-clad laminate, and it is also possible to provide a polyamic acid that gives them. Furthermore, the polyamic acid, polyimide, etc. according to the present invention are manufactured using an acid anhydride component obtained from a bio-based raw material as a raw material, and thus can contribute to carbon neutrality, circular economy, and sustainable product development.

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described.

[0013] <Polyamic acid, polyimide> The polyamic acid of the present embodiment is a precursor of polyimide, and has an acid anhydride residue which is a tetravalent group derived from a tetracarboxylic dianhydride (hereinafter sometimes simply referred to as "acid anhydride") component, and a diamine residue which is a divalent group derived from a diamine (hereinafter sometimes simply referred to as "diamine") component. When these constituent components are connected and regarded as one repeating unit, it is composed of a polymer of the repeating unit. The structure can be controlled by adjusting the charged amounts (molar ratio) of the acid anhydride component and the diamine component.

[0014] Furthermore, the polyimide of this embodiment is obtained by imidizing the polyamic acid and contains specific acid anhydride residues and specific diamine residues.

[0015] For example, polyamic acids are typically obtained by dissolving a predetermined acid anhydride component and a diamine component in approximately equimolar amounts in an organic solvent and carrying out a polymerization reaction by stirring at a temperature usually in the range of 0 to 100°C for 30 minutes to 24 hours. In the reaction, the reactants are dissolved in the organic solvent so that the resulting precursor is in the range of 5 to 30% by weight, preferably in the range of 10 to 20% by weight. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide, N,N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, and γ-ptylolactone. Two or more of these solvents can be used in combination, and furthermore, aromatic hydrocarbons such as xylene and toluene can also be used in combination.

[0016] In the synthesis of polyamic acids and polyimides, the acid anhydride component and the diamine component may be used individually or in combination of two or more. By selecting the types of acid anhydride and diamine components, and the molar ratio of each when two or more acid anhydrides or diamines are used, physical properties such as thermal conductivity, thermal expansion, heat resistance, adhesion, glass transition temperature, and mechanical strength can be controlled.

[0017] Furthermore, the polyamic acid and polyimide of this embodiment may be used with an end-cap encapsulant. Monoamines or dicarboxylic acids are preferred as end-cap encapsulants. The amount of end-cap encapsulant to be introduced is preferably in the range of 0.0001 moles to 0.1 moles per mole of acid anhydride component, and particularly preferably in the range of 0.001 moles to 0.05 moles. Recommended monoamine end-cap encapsulants include, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, aniline, and 4-methylaniline. Of these, benzylamine and aniline can be suitably used. Dicarboxylic acid end-cap encapsulants are preferred, and some of them may be cyclized. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, cyclopentane-1,2-dicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid are recommended. Of these, phthalic acid and phthalic anhydride can be preferably used.

[0018] The synthesized polyamic acid is usually advantageous to use as a reaction solvent solution, but it can be concentrated, diluted, or replaced with other organic solvents as needed. Furthermore, polyamic acid is advantageous to use because it generally has excellent solvent solubility. The method for imidizing the polyamic acid is not particularly limited; for example, a heat treatment such as heating in the aforementioned solvent at a temperature range of 80°C to 400°C for 1 to 24 hours is preferably employed.

[0019] Furthermore, while there are no restrictions on the polyamic acid, it is preferable to adjust the viscosity to be in the range of 1,000 to 200,000 cP by adjusting the concentration and weight-average molecular weight (Mw). If the viscosity is too high, it can be diluted by adding a solvent. The weight-average molecular weight (Mw) of the polyamic acid is preferably in the range of 10,000 to 500,000, and more preferably in the range of 50,000 to 500,000. If the weight-average molecular weight is less than 10,000, the strength of the film tends to decrease and it becomes prone to embrittlement. On the other hand, if the weight-average molecular weight exceeds 500,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur during the coating process.

[0020] The acid anhydride residues and diamine residues contained in the polyamic acid and polyimide of this embodiment will be described below.

[0021] (Acid anhydride component, acid anhydride residue) First, the acid anhydride component used in the polyamic acid and polyimide of this embodiment is an acid anhydride component represented by the following formula (A1). [ka]

[0022] The acid anhydride represented by formula (A1) is derived from dianhydrohexitol such as isosorbide, isomannide, or isoidide, which are cellulose derivatives. Because it is derived from bio-based raw materials, it can provide polyamic acids and polyimides that can contribute to carbon neutrality, the circular economy, and sustainable product development. Furthermore, these compounds have a bulky and rigid alicyclic structure, which can impart transparency and thermoplasticity. Formula (A1) is shown without specifying the isomer structure derived from isosorbide, isomannide, or isoidide, but specifically it is represented by (A1-1) to (A1-3) below. (A1-1) represents isosorbide-bis(trimellitate anhydride) derived from isosorbide, (A1-2) represents isomannide-bis(trimellitate anhydride) derived from isomannide, and (A1-3) represents isoidide-bis(trimellitate anhydride) derived from isoidide. Among these, isosorbide is widely used in pharmaceuticals, and from the viewpoint of price and availability, the compound (A1-1) is preferred in this embodiment. [ka]

[0023] These compounds of formulas (A1-1) to (A1-3) can each be produced by conventionally known methods, and the production method is not limited. For example, they can be produced by reacting isosorbide, isomannide, or isoidide with a trimellitic anhydride compound such as trimellitic anhydride chloride. In this embodiment, these compounds of formulas (A1-1) to (A1-3) can be used individually or as a mixture of two or more.

[0024] In the polyamic acid and polyimide of this embodiment, the acid anhydride component represented by formula (A1) is contained in an amount of 10 to 90 mol% relative to 100 mol% of the total acid anhydride components. That is, the acid anhydride residues (A1) derived from these acid anhydride components are set to be 10 to 90 mol% relative to 100 mol% of the total acid anhydride residues in the produced polyamic acid and polyimide. If the acid anhydride component represented by formula (A1) (acid anhydride residues (A1)) is less than 10 mol%, the amount of biomass in the polyamic acid and polyimide will be small, and effects such as carbon neutrality cannot be fully obtained. In addition, the acid anhydride component represented by formula (A1) also plays a role in providing flexibility to the molecular chain, and if it is less than 10 mol%, it may become brittle and its elongation may be low.

[0025] On the other hand, if the acid anhydride component represented by formula (A1) (acid anhydride residue (A1)) exceeds 90 mol%, the heat resistance may decrease. That is, as the amount of the acid anhydride component represented by formula (A1) (acid anhydride residue (A1)) increases, the content of other acid anhydride components (acid anhydride residues) decreases relatively, so the effect of blending other acid anhydride components (acid anhydride residues) represented by formula (A2), which will be described later, may not be obtained. Therefore, considering this point of heat resistance, the preferred content of the acid anhydride component represented by formula (A1) (acid anhydride residue (A1)) is 10 to 80 mol%, more preferably 10 to 70 mol%, even more preferably 10 to 60 mol%, and even more preferably 10 to 50 mol%. As for the lower limit, in order to sufficiently obtain effects such as carbon neutrality, it is more preferably 20 mol% or more.

[0026] Furthermore, in the polyamic acid and polyimide of this embodiment, it is preferable to include, in addition to the acid anhydride component represented by formula (A1), an acid anhydride residue (A2) derived from the acid anhydride component represented by the following formula (A2) in an amount of 10 to 90 mol% relative to the total anhydride residues. [ka]

[0027] Here, in equation (A2), A independently represents one of the groups selected from the following equations (A2-1) to (A2-4). [ka]

[0028] Here, in formulas (A2-1) to (A2-4), Y independently represents a single bond, -CO-, -O-, -S-, -SO2-, -COO-, or -NHCO-, R2 independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group, or a trifluoromethyl group, and n2 independently represents an integer from 0 to 4.

[0029] Having an acid anhydride component represented by formula (A2) (acid anhydride residue (A2)) has the effect of controlling the orientation of molecules in polyimide, suppressing the increase in the coefficient of thermal expansion (CTE), and improving heat resistance, etc., so that the polyimide and resin film formed using the polyamic acid of this embodiment can have a lower CTE and improved heat resistance.

[0030] The acid anhydride component represented by formula (A2) is not limited and can be selected and used from known acid anhydride components. Examples of acid anhydride components having the group represented by formula (A2-1) include pyromellitic anhydride (PMDA).

[0031] Furthermore, examples of acid anhydride components having the group represented by formula (A2-2) include 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, and 1,4,5,8-naphthalenetetracarboxylic dianhydride.

[0032] Furthermore, examples of acid anhydride components having the group represented by formula (A2-3) include 3,3',4,4'- or 2,3',3,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-, 2,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-thionitetracarboxylic dianhydride, 5-isobenzofuranic acid, and N-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)-1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide.

[0033] Furthermore, examples of acid anhydride components having the group represented by formula (A2-4) include bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)1,4-phenylene (TAHQ).

[0034] Among these, pyromellitic anhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and / or 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) are more preferred embodiments from the viewpoint of heat resistance and availability.

[0035] A more preferred content of the acid anhydride component represented by formula (A2) is 20 to 90 mol%, more preferably 30 to 90 mol%, and even more preferably 50 to 90 mol%, relative to the total acid anhydride component. That is, the acid anhydride residue (A2) derived from the acid anhydride component represented by formula (A2) is more preferably 20 to 90 mol%, more preferably 30 to 90 mol%, and even more preferably 50 to 90 mol%, relative to 100 mol% of the total acid anhydride residues of the polyamic acid and polyimide produced.

[0036] Furthermore, as a third acid anhydride component other than the acid anhydride components represented by formulas (A1) and (A2) above, any other tetracarboxylic anhydride component that can be used in the production of polyamic acids and polyimides in general can be selected and used, as long as it does not hinder the effects and objectives of the present invention, but aromatic tetracarboxylic dianhydrides are preferred. Alternatively, anhydrides of tetracarboxylic acids having an aliphatic skeleton may be used. When using these third acid anhydride components, it is preferable to use them in an amount of 50 mol% or less of the total acid anhydride components, more preferably 30 mol% or less, and more preferably 10 mol% or less.

[0037] (Diamine component, diamine residue) The diamine components used in the polyamic acid and polyimide of this embodiment must be one or more diamine components selected from the group consisting of the following formulas (B1-1) to (B1-3). [ka]

[0038] Here, in formulas (B1-1) to (B1-3), R1 independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, n1 independently represents an integer from 0 to 4, X independently represents -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -CO-, -SO2-, -NH-, or -(CH2)m-, and m represents an integer from 1 to 3.

[0039] Since the diamine components represented by formulas (B1-1) to (B1-3) have a flexible molecular structure, it is thought that by using at least one of these diamine components, the flexibility of the polyimide molecular chain can be improved, thermoplasticity can be imparted, and adhesion (peel strength) due to molecular chain entanglement can also be improved.

[0040] In order to exhibit these properties, the polyamic acid and polyimide of this embodiment must contain the diamine components represented by formulas (B1-1) to (B1-3) in an amount of 10 to 100 mol% relative to 100 mol% of the total diamine components. That is, the diamine residues (B1) derived from these diamine components should be 10 to 100 mol% relative to 100 mol% of the total diamine residues of the polyamic acid and polyimide produced. Preferably, it is 20 to 80 mol%, and more preferably 20 to 70 mol%.

[0041] The diamine components represented by formulas (B1-1) to (B1-3) are not limited and can be selected from known diamines.

[0042] Examples of the diamine component represented by formula (B1-1) include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether (4,4'-DAPE), and 4,4'-diaminobenzophenone.

[0043] Examples of the diamine component represented by formula (B1-2) include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), and 1,4-bis(4-aminophenoxy)benzene (TPE-Q).

[0044] Examples of diamine components represented by formula (B1-3) include 2,2-bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), bis[4-(3-aminophenoxy)phenyl]sulfone (m-BAPS), and 4,4'-bis(4-aminophenoxy)benzophenone.

[0045] Among the diamine components represented by formulas (B1-1) to (B1-3), it is preferable to use a compound in which the linking group X and the amino group are in the para position, and more preferably a compound in which both the X group and the two terminal amino groups are in the para position. For example, a more preferable embodiment is to use one or more diamine components selected from the group consisting of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 4,4'-diaminodiphenyl ether (4,4'-DAPE), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), and bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS). By using a compound in which the X group and the amino group are in the para position in this way, the increase in crystalline components tends to be suppressed, which is thought to increase the entanglement between molecules and improve adhesion (peel strength).

[0046] Furthermore, in the polyamic acid and polyimide of this embodiment, it is preferable to contain, in addition to the diamine components (diamine residue (B1)) represented by formulas (B1-1) to (B1-3) above, 10 to 90 mol% of diamine residue (B2) derived from the diamine component represented by the following formula (B2) relative to the total number of diamine residues.

[0047] [ka]

[0048] Here, in formula (B2), Z independently represents a single bond, -COO-, or -NHCO-; R3 independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group, or a trifluoromethyl group; n3 independently represents an integer from 0 to 4; and a represents an integer from 0 to 2.

[0049] Diamine components represented by formula (B2) such as the one shown have a rigid structure of a biphenyl ring, and preferably have a monovalent hydrocarbon group, an alkoxy group, or a trifluoromethyl group on the side chains of the two benzene rings. This strengthens intermolecular interactions, making it difficult for the molecular chains to move even when heated, and reducing intramolecular rotation. The Z group is also a single bond, -COO-, or -NHCO-, which has relatively low flexibility. These configurations result in a diamine component that provides high planarity. This leads to suppression of molecular chain motion, improving heat resistance, such as improving the glass transition temperature (Tg) and suppressing thermal deformation. For example, when a polyamic acid layer using this diamine component is applied, and then a main low-thermal-expansion polyamic acid is applied on top of it, and then dried and cured, the polyamic acid or polyimide layer can withstand the pressure generated by solvent volatilization, contributing to the suppression of foaming of the polyimide laminated film. Furthermore, it is believed to contribute to suppressing heat wrinkles during the manufacturing and transport of polyimide films and metal-clad laminates, as well as deformation and wrinkles during copper foil pressing.

[0050] The diamine component represented by formula (B2) is not limited and can be selected from known diamines. Examples include 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB, also known as m-tolidine, 2,2'-dimethylbenzidine, or 4,4'-diamino-2,2'-dimethylbiphenyl), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), paraphenylenediamine (PPD), 4,4'-diaminobiphenyl (DAB), and 4,4'-diaminobenzanilide (DABA).

[0051] In the polyamic acid and polyimide of this embodiment, in order to adjust the expression of properties due to the diamine component represented by formula (B2) and the expression of properties due to the diamine components represented by the aforementioned formulas (B1-1) to (B1-3), it is preferable that the diamine component represented by formula (B2) is contained in an amount of 30 to 80 mol% of 100 mol% of the total diamine components. That is, the diamine residues derived from this diamine component represented by formula (B2) are preferably 30 to 80 mol% of 100 mol% of the total diamine residues.

[0052] Other diamine components not mentioned above can be selected from all other diamine components that can be used in the synthesis of polyimides in general, as long as they do not hinder the effects or objectives of the present invention, but aromatic diamine compounds are preferred. Diamine compounds having an aliphatic skeleton may also be used. When using such other diamine components, it is preferable to use them in an amount of 50 mol% or less of the total diamine components, more preferably 30 mol% or less, and more preferably 10 mol% or less.

[0053] [Total content of acid anhydride residues (A1) and diamine residues (B1)] In this embodiment, the polyamic acid and polyimide must have a total content of the acid anhydride component represented by formula (A1) and the diamine components represented by formulas (B1-1) to (B1-3), which are used as essential components as described above. This total content must be 20 to 150 mol% relative to the total of 200 mol% of all acid anhydride components and 100 mol% of all diamine components. That is, the total content of acid anhydride residues (A1) and diamine residues (B1) must be 20 to 150 mol% relative to the total of 200 mol% of all acid anhydride residues and 100 mol% of all diamine residues. If the content is less than 20 mol%, the amount of biomass in the polyamic acid and polyimide will be small, and effects such as carbon neutrality may not be sufficiently obtained. Furthermore, there may be a deficiency of the flexible diamine components (diamine residue (B1)) of formulas (B1-1) to (B1-3), which may result in unsatisfactory adhesion. On the other hand, if the content exceeds 150 mol%, the heat resistance may decrease. In this embodiment, the total content of acid anhydride residue (A1) and diamine residue (B1) is preferably 20 to 150 mol%.

[0054] (Other ingredients) The polyamic acid and polyimide of this embodiment may optionally contain fillers and other components such as silicon dioxide, aluminum oxide, boron nitride, magnesium oxide, beryllium oxide, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, and metal salts of organophosphinic acids, as long as they do not hinder the objectives of the present invention. These components can be used individually or in combination of two or more.

[0055] <Resin film> The resin film of this embodiment has one or more polyimide layers, and at least one polyimide layer is composed of polyimide obtained by imidizing the polyamic acid of this embodiment. It may be a film (sheet) made of insulating resin, or it may be an insulating resin film laminated on a substrate such as copper foil, glass plate, polyimide film, polyamide film, polyester film, or other resin sheet.

[0056] As described above, the resin film of this embodiment uses an acid anhydride component represented by formula (A1), which is a bio-derived raw material, as an essential component, and in addition to obtaining polyimide and resin films with a relatively high biomass content, it also uses diamine components represented by formulas (B1-1) to (B1-3) as essential components, and furthermore, the content of these components is within a predetermined range, resulting in particularly excellent adhesion and heat resistance.

[0057] In this embodiment, regarding heat resistance, the resin film preferably has a glass transition temperature (Tg) of 250°C or higher, more preferably 285°C or higher, and even more preferably 300°C or higher. In particular, an embodiment having a Tg in the range of 285°C or higher is preferable because it can withstand the pressure caused by solvent evaporation.

[0058] Furthermore, regarding heat resistance, the resin film of this embodiment preferably has a 5% thermal weight loss temperature (Td5) of 400°C or higher in a thermal decomposition test. A Td5 of 400°C or higher makes thermal decomposition during curing less likely, reducing the amount of decomposed volatile components within the resin film layer and thus reducing foaming. More preferably, Td5 should be 410°C or higher, and even more preferably 420°C or higher. By controlling the temperature within this range, foaming can be reduced, resulting in sufficient heat resistance.

[0059] Furthermore, regarding adhesion, in embodiments where the resin film according to this embodiment is used as an insulating resin layer in a metal-clad laminate described later, the 180° peel strength with respect to the metal layer is preferably 0.7 kN / m or more, and more preferably 0.8 kN / m. The wiring width can be appropriately set depending on the application, but for example, it can be 1 to 3 mm.

[0060] Furthermore, the resin film of this embodiment also exhibits excellent low thermal expansion. Here, the coefficient of thermal expansion (CTE) is usually 80 ppm / K or less, preferably 70 ppm / K or less, more preferably 60 ppm / K or less, even more preferably 10 ppm / K to 60 ppm / K, and sufficiently preferably 20 ppm / K to 60 ppm / K. By controlling it within this range, deformation such as curling can be suppressed, and high dimensional stability can be ensured.

[0061] Furthermore, in this embodiment, the elastic modulus of the resin film is preferably adjusted based on the content of the acid anhydride component represented by formula (A2) and the diamine component represented by formula (B2) described above. The elastic modulus is preferably 2.5 GPa or higher, more preferably 3.0 GPa or higher, and even more preferably 3.2 GPa or higher.

[0062] The resin film of this embodiment preferably has an overall thickness in the range of 2 to 100 μm, and more preferably in the range of 4 to 50 μm. If the thickness is less than 2 μm, problems such as wrinkles forming in the metal foil are likely to occur during the transport process when manufacturing the metal-clad laminate. Conversely, if the thickness exceeds 100 μm, it tends to be disadvantageous in terms of toughness, flexibility, and productivity.

[0063] Examples of methods for forming the polyimide (layer) and resin film in this embodiment include: [1] a method of producing a resin film by applying and drying a polyamic acid solution to a support substrate (e.g., a metal layer), followed by imidation (hereinafter referred to as the casting method); and [2] a method of producing a resin film by applying and drying a polyamic acid solution to a support substrate, peeling off the polyamic acid gel film from the support substrate, and then imidating it. Furthermore, when the polyimide consists of multiple layers, examples of the manufacturing method include: [3] a method of repeatedly applying and drying a polyamic acid solution to a support substrate, followed by imidation (hereinafter referred to as the sequential coating method); and [4] a method of simultaneously applying and drying a polyamic acid laminated structure to a support substrate by multilayer extrusion, followed by imidation (hereinafter referred to as the multilayer extrusion method). From the viewpoint of controlling dimensional stability and adhesion to the metal layer, it is preferable to form the polyimide layer (resin film and the insulating resin layer and metal-clad laminate described later using the same) by the casting method or sequential coating method.

[0064] The method for applying the polyamic acid solution (or polyimide solution) onto the substrate is not particularly limited, and it can be applied using a coater such as a comma, die, knife, or lip. When forming a multilayer polyimide layer, it is preferable to repeatedly apply the polyamic acid solution (or polyimide solution) to the substrate and dry it. The insulating resin layer (described later) in this embodiment may be formed from only a single layer of polyimide, or from multiple layers of polyimide.

[0065] <Metal-clad laminate> (metal layer) The material of the metal layer is not particularly limited, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, metal elements such as copper, iron, or nickel, or indium tin oxide (ITO) are preferred, and copper (copper foil) is more preferred. As for the copper foil, either electrolytic copper foil or rolled copper foil can be used. When selecting these metal layers, the properties required for the intended use, such as the conductivity of the metal layer, the light transmittance of the polyimide layer, and the adhesion to the polyimide layer, should be selected accordingly. There are no particular restrictions on the shape of the metal layer, but it may be processed as appropriate depending on the application. A roll-shaped form formed into a long length is preferably used.

[0066] The thickness of the metal layer is not particularly limited, but is preferably 100 μm or less, more preferably in the range of 0.1 to 70 μm, and even more preferably in the range of 1 to 50 μm. For heat dissipation applications, such as in automotive applications, large currents are often passed through, so a thicker metal layer (e.g., copper foil) is preferred to withstand the large currents. On the other hand, if the metal layer is too thick, the flexibility and processability of the laminated substrate tend to decrease, and the weight tends to increase.

[0067] (Insulating resin layer) In this embodiment, the metal-clad laminate comprises an insulating resin layer consisting of one or more layers, and a metal layer laminated on at least one side (one side) or both sides (both sides) of the insulating resin layer, and it is preferable that at least one layer of the insulating resin layer contains the aforementioned resin film.

[0068] If the insulating resin layer includes a resin film consisting of multiple polyimide layers, it may have a two-layer structure consisting of a polyimide layer (P1) directly laminated to the metal layer and a polyimide layer (P2) not directly laminated to the metal layer. While not limited to configurations 1-4 shown below, it may also have three layers, and the third polyimide layer (P3) may be laminated in the order of (P1) / (P2) / (P3). M1 and M2 represent metal layers, and M1 and M2 may be the same or different. The polyimide layer (P1) directly laminated to the metal layer and the third polyimide layer (P3) may have the same composition. For example, when forming multiple polyimide layers by casting, a two-layer structure may be formed in which a polyimide layer (P1) directly laminated to the metal layer from the casting side and a polyimide layer (P2) not directly laminated to the metal layer are laminated in this order. Alternatively, a three-layer structure may be formed in which a polyimide layer (P1) directly laminated to the metal layer from the casting side, a polyimide layer (P2) not directly laminated to the metal layer, and a third polyimide layer (P3) are laminated in this order. Here, "casting surface" refers to the surface on the support side when forming the polyimide layer. The support may be the metal layer of a metal-clad laminate, glass, or a support when forming a gel film, etc. Note that in multiple polyimide layers, the surface opposite to the casting surface is described as the "laminate surface," but unless otherwise specified, the laminate surface may or may not have a metal layer laminated to it.

[0069] Configuration 1;M1 / P1 / P2 Configuration 2; M1 / P1 / P2 / P1 (or P3) Configuration 3: M1 / P1 / P2 / P1 (or P3) / M2 (or M1) Configuration 4: M1 / P1 / P2 / P1 (or P3) / P2 / P1 (or P3) / M2 (or M1)

[0070] The polyimides constituting the polyimide layer (P1) and the polyimide layer (P3) are preferably thermoplastic polyimides, which improves the adhesion as an insulating resin layer and makes it suitable for application as an adhesive layer to a metal layer.

[0071] A preferred embodiment of the insulating resin layer comprises a thermoplastic polyimide layer (P1) and a non-thermoplastic polyimide layer (P2) composed of non-thermoplastic polyimide, wherein at least one side of the non-thermoplastic polyimide layer (P2) has a polyimide layer (P1) that becomes the thermoplastic polyimide layer. That is, the polyimide layer (P1) may be provided on one or both sides of the non-thermoplastic polyimide layer.

[0072] Here, the non-thermoplastic polyimide layer constitutes a low-thermal-expansion polyimide layer, and the thermoplastic polyimide layer constitutes a high-thermal-expansion polyimide layer. Generally, a low-thermal-expansion polyimide layer refers to a polyimide layer whose coefficient of thermal expansion (CTE) is preferably in the range of 1 ppm / K to 25 ppm / K, more preferably in the range of 3 ppm / K to 25 ppm / K. Generally, a high-thermal-expansion polyimide layer refers to a polyimide layer whose CTE is preferably 35 ppm / K or higher, more preferably in the range of 35 ppm / K to 80 ppm / K, and even more preferably in the range of 35 ppm / K to 70 ppm / K. The polyimide layer can be made to have a desired CTE by appropriately changing the combination of raw materials used, thickness, and drying / curing conditions.

[0073] Here, non-thermoplastic polyimide generally refers to polyimide that does not soften or become adhesive when heated, but in this embodiment, the storage modulus at 30°C measured using a dynamic viscoelasticity measuring device (DMA) is 1.0 × 10⁻⁶. 9 The Pa is greater than or equal to 1.0 × 10⁻¹⁶, and the storage modulus at 350°C is 1.0 × 10⁻¹⁶. 9 This refers to polyimides with a storage modulus of Pa or higher. Furthermore, thermoplastic polyimides (also called "TPI") generally refer to polyimides whose glass transition temperature (Tg) can be clearly determined. In this embodiment, however, the storage modulus at 30°C measured using DMA is 1.0 × 10⁻⁶. 9 The Pa is greater than or equal to 1.0 × 10⁻¹⁶, and the storage modulus at 300°C is 1.0 × 10⁻¹⁶. 8 This refers to polyimides with a Pa rating of less than 1.5.

[0074] Furthermore, the resin film of this embodiment can be used for either the thermoplastic polyimide layer (P1) or the non-thermoplastic polyimide layer (P2). Although not limited, given that the resin film of this embodiment possesses the adhesive properties and heat resistance described above, it is preferable that it be laminated directly onto the metal layer and applied to the thermoplastic polyimide layer (P1). Using the resin film of this embodiment for the polyimide layer (P1) is preferable because it improves the adhesion (peel strength) with the metal layer. In addition, since it also has heat resistance, it is advantageous in cases where there are two or more layers, such as when a non-thermoplastic polyimide layer (P2) is provided on the polyimide layer (P1), as it can suppress insufficient pressure resistance due to solvent evaporation and foaming due to thermal decomposition. In other words, since non-thermoplastic polyimide layers (P2) are usually thick and have relatively poor solvent permeability, if a polyimide layer with low heat resistance is used as the polyimide layer (P1), when solvents volatilized from the polyimide layer (P1) and polyimide layer (P2) accumulate at the interface between the polyimide layer (P1) and the polyimide layer (P2), the polyimide layer (P1) may not be able to withstand the pressure of the volatilized solvent, potentially causing problems such as swelling. This method is preferable because it can suppress the occurrence of such problems.

[0075] <Method for manufacturing metal-clad laminates> As described above, in this embodiment, the metal-clad laminate is preferably prepared by forming an insulating resin layer, which includes a resin film consisting of one or more polyimide layers, on the metal layer as a supporting substrate using a casting method or a sequential coating method, from the viewpoint of dimensional stability and other factors, but it is not particularly limited. For example, an insulating resin layer including a resin film composed of the polyimide layers of this embodiment may be prepared, a seed layer may be formed by sputtering metal onto it, and then a metal layer may be formed, for example, by plating.

[0076] Alternatively, an insulating resin layer containing the resin film of this embodiment may be prepared, and a metal foil may be laminated thereto by methods such as thermocompression bonding.

[0077] In those cases, the surface of the resin film may be modified, for example, by plasma treatment, in order to improve the adhesion between the resin film and the metal layer.

[0078] Furthermore, when manufacturing a metal-clad laminate having metal layers on both sides, for example, it can be obtained by directly forming an adhesive layer on the polyimide layer of a single-sided metal-clad laminate obtained by the above method, or, if necessary, a layer that does not impair the properties such as transparency of the insulating resin layer, and then laminating the metal layer by means of heat pressing or other means. The heat press temperature when heat pressing the metal layer is not particularly limited, but it is desirable that it be above the glass transition temperature of the polyimide layer adjacent to the metal layer used. The heat press pressure is 1 to 500 kg / m, depending on the type of press equipment used. 2 It is desirable that it be within that range. [Examples]

[0079] The present invention will be described in detail below based on the examples, but the present invention is not limited to the scope of these examples.

[0080] The abbreviations used in this example indicate the following compounds. ISS-TME: Isosorbide-bis(trimellitate anhydride) obtained in Synthesis Example 1 BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride BTDA:3,3',4,4'-benzophenonetetracarboxylic dianhydride PMDA: Pyromellitic dianhydride ODPA: 4,4'-Oxydiphthalic acid dianhydride BAPP: 2,2-Bis[4-(4-aminophenoxy)phenyl]propane m-BAPS: Bis[4-(3-aminophenoxy)phenyl]sulfone m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TFMB: 2,2'-Bis(trifluoromethyl)-4,4'-diaminobiphenyl TPE-Q: 1,4-bis(4-aminophenoxy)benzene 4,4'-DAPE:4,4'-diaminodiphenyl ether DMAc: N,N-dimethylacetamide

[0081] Furthermore, the characteristics evaluated in the examples were assessed according to the evaluation method described below.

[0082] [Viscosity measurement] The viscosity of the polyamic acid solution was measured at 25°C using a cone-plate viscometer with a constant-temperature water bath (manufactured by Tokimec Co., Ltd.).

[0083] [Weight average molecular weight (Mw)] The measurements were performed using gel permeation chromatography (manufactured by Tosoh Corporation, product name: HLC-8220GPC). Polystyrene was used as the standard substance, and N,N-dimethylacetamide was used as the developing solvent.

[0084] [Tensile modulus of elasticity, tensile elongation] Test specimens of polyimide film (10 mm x 15 mm) were prepared, and tensile tests were performed using a Tensilon universal testing machine (Orientec Co., Ltd., RTA-250) at a tensile speed of 10 mm / min in accordance with IPC-TM-650, 2.4.19, to calculate the tensile modulus and tensile elongation.

[0085] [Coefficient of thermal expansion (CTE)] A polyimide film obtained by etching copper foil was cut to a size of 3 mm x 20 mm. Using a thermomechanical analyzer (Hitachi High-Tech Science Corporation, product name: TMA7100), the temperature was raised from 30°C to 260°C at a heating rate of 10°C / min while applying a load of 49 mN. After holding at that temperature for 10 minutes, it was cooled at a rate of 10°C / min, and the average thermal expansion coefficient from 250°C to 100°C was determined.

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

[0087] [Glass transition temperature (Tg)] The dynamic viscoelasticity of a resin film (10 mm x 22.6 mm) was measured using a dynamic thermomechanical analyzer when the temperature was increased from 20°C to 400°C at a rate of 10°C / min, and the glass transition temperature (Tanδ maximum value: °C) was determined.

[0088] [Measurement of Peel Strength] After processing the copper foil of a single-sided copper-clad laminate into a circuit with a width of 1-3 mm, the polyimide layer was fixed to an aluminum plate with double-sided tape, and the peel strength was determined by peeling the copper foil wiring in a 180° direction at a speed of 50 mm / min using a Tensilon tester (manufactured by Toyo Seiki Seisakusho, product name: Strograph VE-1D).

[0089] (Synthesis Example 1) Isosorbide and 30 times dichloromethane were placed in a four-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was stirred to dissolve the isosorbide, and then 1.1 times triethylamine relative to the isosorbide was added. Furthermore, 2.1 times trimellitic acid chloride relative to the isosorbide was added, and the mixture was stirred at 0°C for 20 hours. The precipitate was filtered off, and the filtrate was slowly added dropwise to 30 times its volume of petroleum ether to obtain a white solid. The obtained white solid was filtered off and dried under reduced pressure at 80°C. The obtained white solid was dissolved in deuterated dimethyl sulfoxide (DMSO-d6), 1 Analysis using 1H-NMR identified the target compound as isosorbide-bis(trimellitate anhydride).

[0090] (Synthesis Examples 2-13) To synthesize the polyamic acid solutions described in Synthesis Examples 2-13, under a nitrogen atmosphere, DMAc solvent was added to a 500 ml separable flask to achieve the solid content concentration shown in Table 1. The diamine and acid anhydride components (molar parts) shown in Table 1 were then added, and the mixture was stirred at room temperature for 24 hours to carry out the polymerization reaction and prepare a viscous solution of polyamic acid.

[0091] [Table 1]

[0092] [Evaluation of polyimide film properties and peel strength] (Examples 1-8, Comparative Examples 1-3) Next, the polyamic acid solutions A to K, prepared according to Synthesis Examples 2 to 12 as shown in Table 1, were applied to copper foil (electrolytic copper foil, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., product name: CF-T49A-DS-HD2-12, thickness: 12 μm, Rz = 1.2 μm) so that the thickness after curing was as shown in Table 2. The solutions were then heated and dried at 90 to 140°C to remove the solvent. Subsequently, metal-clad laminates (CCLs) were fabricated by gradually increasing the temperature in the range of 130 to 360°C to laminate an insulating resin layer consisting of a polyimide layer onto the copper foil. To evaluate the properties of the polyimide layer in each metal-clad laminate, the copper foil was etched off to create resin films and metal-clad laminates with circuit processing, and these were evaluated. The evaluation results are shown in Table 2.

[0093] [Table 2]

[0094] [Application to the adhesive layer of metal-clad laminates] (Example 9) A polyamic acid solution D was applied to copper foil (electrolytic copper foil, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., product name: CF-T49A-DS-HD2-12, thickness: 12 μm, Rz = 1.2 μm) to a thickness of 2-3 μm after curing. The solution was then heated and dried at 90-140°C to remove the solvent and form an adhesive layer. On top of this, a polyamic acid solution L was applied to a thickness of 20-25 μm after curing. The solution was then heated and dried at 90-140°C to remove the solvent and form a base layer. Subsequently, a metal-clad laminate (CCL) was fabricated by gradually increasing the temperature in the range of 130-360°C to laminate two polyimide insulating resin layers onto the copper foil. The copper foil was processed into a circuit, and the peel strength between the copper foil and the polyimide layer was measured, yielding a high peel strength of 1.07 kN / m.

[0095] (Example 10) Except for using polyamic acid solution E in the adhesive layer, a metal-clad laminate was prepared in the same manner as in Example 9, with two layers of polyimide insulating resin laminated together. When the peel strength was measured, a high peel strength of 1.04 kN / m was obtained.

[0096] (Example 11) Except for using the polyamic acid solution F in the adhesive layer, a metal-clad laminate was prepared by laminating two polyimide insulating resin layers in the same manner as in Example 9, and when the peel strength was measured, a high peel strength of 0.87 kN / m was obtained.

[0097] (Comparative Example 4) In an attempt to produce a metal-clad laminate by laminating two polyimide insulating resin layers in the same manner as in Example 9, except that the polyamic acid solution for the adhesive layer was A, foaming occurred during the stepwise heating process, and the metal-clad laminate could not be produced.

[0098] (Comparative Example 5) In an attempt to produce a metal-clad laminate by laminating two polyimide insulating resin layers in the same manner as in Example 9, except that the polyamic acid solution for the adhesive layer was B, foaming occurred during the stepwise heating process, and the metal-clad laminate could not be produced.

[0099] (Comparative Example 6) Except for using polyamic acid solution C in the adhesive layer, a metal-clad laminate was prepared by laminating two polyimide insulating resin layers in the same manner as in Example 9, and when the peel strength was measured, it was 0.66 kN / m, which was lower than that of Examples 9 to 11.

[0100] From the results of Comparative Examples 4-6 and Examples 9-11, it can be seen that even when a low-CTE and low-solvent-permeable non-thermoplastic polyamic acid is applied and cured on the polyamic acid according to the embodiment of the present invention, it exhibits excellent heat resistance and adhesion, and does not foam during curing, and high copper foil peel strength can be achieved even after curing.

[0101] Although embodiments of the present invention have been described in detail above for illustrative purposes, the present invention is not limited to the above embodiments.

Claims

1. A polyamic acid containing an acid anhydride residue derived from an acid anhydride component and a diamine residue derived from a diamine component, The total amount of acid anhydride residues contains 10 to 90 mol% of an acid anhydride residue (A1) derived from an acid anhydride component represented by the following formula (A1), The total amount of diamine residues contains 10 to 100 mol% of a diamine residue (B1) derived from one or more diamine components selected from the group consisting of the following formulas (B1-1) to (B1-3), A polyamic acid characterized by containing a total of 20 to 150 mol% of the acid anhydride residue (A1) and diamine residue (B1) relative to the sum of all acid anhydride residues and all diamine residues. 【Chemistry 1】 【Chemistry 2】 [In formulas (B1-1) to (B1-3), R １ This independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, n １ The integers 0 through 4 are independent of each other, and X is independent of each other, such as -O-, -S-, and -CH. ２ -, -CH(CH ３ )-,-C(CH ３ ) ２ -, -CO-, -SO ２ -, -NH- or -(CH ２ ) indicates m-, where m is an integer from 1 to 3.

2. The polyamic acid according to claim 1, characterized in that it contains 10 to 90 mol% of an acid anhydride residue (A2) derived from an acid anhydride component represented by the following formula (A2) relative to the total acid anhydride residues. 【Transformation 3】 [In formula (A2), A independently represents one of the groups selected from the following formulas (A2-1) to (A2-4).] 【Chemistry 4】 [In formulas (A2-1) to (A2-4), Y is independently a single bond, -CO-, -O-, -S-, -SO ２ -, -COO- or -NHCO-, and R ２ independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group or a trifluoromethyl group, and n ２ independently represents an integer of 0 to 4.]

3. The polyamic acid according to claim 1, characterized in that it contains 10 to 90 mol% of a diamine residue (B2) derived from a diamine component represented by the following formula (B2) relative to the total number of diamine residues. 【Transformation 5】 [In formula (B2), Z independently represents a single bond, -COO-, or -NHCO-, R ３ This independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group, or a trifluoromethyl group, n ３ [where 'a' independently represents an integer between 0 and 4, and 'a' represents an integer between 0 and 2.]

4. The polyamic acid according to claim 1, characterized in that it contains 10 to 50 mol% of an acid anhydride residue (A1) derived from the acid anhydride component represented by formula (A1) with respect to the total acid anhydride residues.

5. The polyamic acid according to claim 1, characterized in that the diamine residue (B1) is a diamine residue derived from one or more diamine components selected from the group consisting of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 4,4'-diaminodiphenyl ether (4,4'-DAPE), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), and bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS).

6. A polyimide obtained by imidizing a polyamic acid according to any one of claims 1 to 5.

7. A resin film comprising a polyimide obtained by imidizing a polyamic acid according to any one of claims 1 to 5.

8. The resin film according to claim 7, characterized in that the glass transition temperature is 250°C or higher.

9. The resin film according to claim 7, characterized in that the glass transition temperature is 285°C or higher.

10. The resin film according to claim 7, characterized in that the 5% weight loss temperature (Td5) is 400°C or higher.

11. A metal-clad laminate comprising an insulating resin layer consisting of one or more layers, and a metal layer laminated on at least one surface of the insulating resin layer, A metal-clad laminate characterized in that the insulating resin layer includes the resin film described in claim 7.

12. The metal-clad laminate according to claim 11, characterized in that the 180° peel strength between the metal layer and the insulating resin layer is 0.8 kN / m or more.

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