Amino acid oligomers, varnishes, cured products, and composite materials having a specific composition

Abstract

To provide an amidoacid oligomer or the like that can improve melt fluidity.SOLUTION: The amidoacid oligomer or the like according to one embodiment of the present invention includes two particular types of structural unit as structural unit derived from aromatic tetracarboxylic acid.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to amino acid oligomers, varnishes, cured products, and composite materials having a specific composition.

Background Art

[0002] Polyimide has the highest level of heat resistance among polymers and is also excellent in mechanical properties and electrical properties. Therefore, polyimide is used as a material in a wide range of fields such as aerospace and electric and electronic.

[0003] For example, Patent Document 1 discloses an all-aromatic polyimide precursor powder composed of a salt formed from a specific aromatic diamine and a specific aromatic tetracarboxylic acid. Patent Document 1 also discloses adding an aromatic derivative having a dicarboxylic acid or an aromatic derivative having one amine group as a terminal blocking agent during the production of the polyimide precursor powder.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above-mentioned conventional technologies had room for improvement from the viewpoint of melt fluidity. One aspect of the present invention aims to realize an amino acid oligomer or the like that can improve melt fluidity.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the melt fluidity can be improved by using an amic acid oligomer containing two specific structural units derived from aromatic tetracarboxylic acids, and have completed the present invention. The present invention includes the following aspects. <1> An amic acid oligomer represented by the following formula (1).

[0007]

Chemical formula

[0008] 〔In formula (1), n is an integer of 1 ≦ n ≦ 100, Q represents a tetravalent residue (A') derived from aromatic tetracarboxylic acids (A), where the tetravalent residue (A') includes a structural unit (A1) represented by formula (2) and a structural unit (A2) represented by formula (3),

[0009]

Chemical formula

[0010] The molar ratio of the structural unit (A1) to the structural unit (A2) is in the range of 80 / 20 to 20 / 80, The tetravalent residue (A') contains 50 mol% or more of the total of the structural unit (A1) and the structural unit (A2), Y represents a divalent residue (B') derived from aromatic diamine (B), where the divalent residue (B') includes a structural unit (B1) represented by formula (4) or includes a structural unit (B1) represented by formula (4) and a structural unit (B2) represented by formula (5),

[0011]

Chemical formula

[0012] X 1represents a direct bond or a divalent linking group selected from the group consisting of a methylene group, an ether group, a carbonyl group, a sulfonyl group, a sulfide group, an amide group, an ester group, an isopropylidene group, a hexafluoroisopropylidene group, a 9,9-fluorenylidene group, an m-phenylenedioxy group, and a p-phenylenedioxy group, (i) None of R 1 ~R 10 corresponds to an aryl group or a halogenated aryl group, and one of R 1 ~R 5 represents a direct bond to the nitrogen atom in the amide bond with the acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, and one of R 6 ~R 10 represents a direct bond to the nitrogen atom in the amide bond with the acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, or (ii) One of R 1 ~R 5 represents one selected from the group consisting of an aryl group and a halogenated aryl group, another one represents a direct bond to the nitrogen atom in the amide bond with the acid anhydride component, and the remaining three each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, and one of R 6 ~R 10 represents a direct bond to the nitrogen atom in the amide bond with the acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, or, (iii) R 1 ~R 5Any one of them represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, and R 6 ~R 10 Any one of them represents one selected from the group consisting of an aryl group and a halogenated aryl group, any one of the others represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining three each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, provided that R 3 and R 8 do not simultaneously represent a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, The molar ratio of the structural unit (B1) to the structural unit (B2) is in the range of 100 / 0 to 20 / 80, The divalent residue (B') contains 50 mol% or more in total of the structural unit (B1) and the structural unit (B2), Z is a structural unit selected from the group consisting of a structural unit (C) represented by the following formula (6) and a structural unit derived from an aromatic diamine (B),

[0013]

Chemical formula

[0014] In 100 mol% of the said Z, the content of the structural unit (C) represented by the said formula (6) is 85 mol% or more and 100 mol% or less.〕 <2>The amic acid oligomer according to <1>, wherein the structural unit (B1) is a structural unit derived from 3,4'-diaminodiphenyl ether. <3>A varnish obtained by dissolving the amic acid oligomer according to <1> or <2> in a solvent having a boiling point of 135°C or lower. <4>The solvent of the varnish according to <3> is at least one solvent selected from the group consisting of a mixed solvent of an alcohol-based solvent and an ether-based solvent, a single solvent of a hydroxyether-based solvent, a mixed solvent of an alcohol-based solvent and a hydroxyether-based solvent, a mixed solvent of an ether-based solvent and a hydroxyether-based solvent, and a mixed solvent of an alcohol-based solvent, an ether-based solvent, and a hydroxyether-based solvent. <5>The solvent of the varnish according to <4> is a single solvent of a hydroxyether-based solvent or a mixed solvent of an ether-based solvent and a hydroxyether-based solvent. <6>An imide oligomer obtained from the amino acid oligomer according to <1> or <2>. <7>A cured product obtained by heat-curing the amino acid oligomer according to <1> or <2>, the varnish according to any one of <3> to <5>, or the imide oligomer according to <6>. <8>The cured product according to <7>, further comprising reinforcing fibers.

Advantages of the Invention

[0015] According to one aspect of the present invention, an amino acid oligomer capable of improving melt fluidity can be provided.

Embodiments for Carrying Out the Invention

[0016] Embodiments of the present invention will be described in detail below. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)".

[0017] 〔1. Amino Acid Oligomer〕 The amino acid oligomer according to one embodiment of the present invention is represented by the following formula (1).

[0018]

Chemical formula

[0019] 〔In formula (1), n is an integer satisfying 1 ≦ n ≦ 100, Q represents a tetravalent residue (A') derived from aromatic tetracarboxylic acids (A), wherein the tetravalent residue (A') includes a structural unit (A1) represented by formula (2) and a structural unit (A2) represented by formula (3),

[0020]

Chemical formula

[0021] The molar ratio of the structural unit (A1) to the structural unit (A2) is in the range of 80 / 20 to 20 / 80, and the tetravalent residue (A') contains 50 mol% or more of the total of the structural unit (A1) and the structural unit (A2), Y represents a divalent residue (B') derived from aromatic diamines (B), wherein the divalent residue (B') includes a structural unit (B1) represented by formula (4) or includes a structural unit (B1) represented by formula (4) and a structural unit (B2) represented by formula (5),

[0022]

Chemical formula

[0023] X 1 represents a direct bond or a divalent linking group selected from the group consisting of a methylene group, an ether group, a carbonyl group, a sulfonyl group, a sulfide group, an amide group, an ester group, an isopropylidene group, a hexafluoroisopropylidene group, a 9,9-fluorenylidene group, an m-phenylenedioxy group, and a p-phenylenedioxy group, (i) None of R 1 ~R 10 corresponds to an aryl group or a halogenated aryl group, and R 1 ~R 5Any one of them represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, and R 6 ~R 10 Any one of them represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, or (ii) Any one of R 1 ~R 5 represents one selected from the group consisting of an aryl group and a halogenated aryl group, any one of the others represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining three each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, and R 6 ~R 10 Any one of them represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, or (iii) Any one of R 1 ~R 5 represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group, and R 6 ~R 10One of them represents one selected from the group consisting of an aryl group and a halogenated aryl group, another one represents a direct bond with a nitrogen atom in an amide bond with an acid anhydride component, and the remaining three each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group, a carboxyl group, and an alkoxy group. However, R 3 and R 8 do not simultaneously represent a direct bond with a nitrogen atom in an amide bond with an acid anhydride component. The molar ratio of the structural unit (B1) to the structural unit (B2) is in the range of 100 / 0 to 20 / 80. The divalent residue (B') contains 50 mol% or more in total of the structural unit (B1) and the structural unit (B2). Z is a structural unit selected from the group consisting of a structural unit (C) represented by the following formula (6) and a structural unit derived from an aromatic diamine (B).

[0024]

Chemical formula

[0025] In 100 mol% of the said Z, the content of the structural unit (C) represented by the said formula (6) is 85 mol% or more and 100 mol% or less. The said amic acid oligomer contains a structural unit (A1) and a structural unit (A2) as structural units derived from aromatic tetracarboxylic acids. Therefore, the said amic acid oligomer and the imide oligomer obtained from the said amic acid oligomer exhibit excellent melt fluidity. In this specification, the melt fluidity means the fluidity when the solid of the amic acid oligomer and the solid of the imide oligomer are melted by heating.

[0026] The degree of polymerization n satisfies 1 ≦ n ≦ 100, preferably 2 ≦ n ≦ 75, more preferably 2 ≦ n ≦ 50, still more preferably 2 ≦ n ≦ 30, and particularly preferably 2 ≦ n ≦ 10. If n is within the said range, it is preferable from the viewpoint of melt fluidity.

[0027] The amino acid oligomer may be an aggregate of a plurality of types of amino acid oligomers represented by formula (1).

[0028] <1-1. Aromatic tetracarboxylic acids (A)> The amino acid oligomer contains a tetravalent residue (A') derived from aromatic tetracarboxylic acids (A). The tetravalent residue (A') contains at least a structural unit (A1) and a structural unit (A2).

[0029] Examples of the aromatic tetracarboxylic acids (A) include acid derivatives such as aromatic tetracarboxylic acids, aromatic tetracarboxylic dianhydrides, esters of aromatic tetracarboxylic acids, and salts. When the name of the aromatic tetracarboxylic acids (A) is appended with "~compound" hereinafter, it means a concept that includes acid derivatives such as aromatic tetracarboxylic acids, aromatic tetracarboxylic dianhydrides, esters of aromatic tetracarboxylic acids, and salts.

[0030] The structural unit (A1) is a tetravalent residue derived from a pyromellitic acid compound. Examples of the pyromellitic acid compound include acid derivatives such as pyromellitic acid, pyromellitic dianhydride (PMDA), esters of pyromellitic acid, and salts.

[0031] The structural unit (A2) is a tetravalent residue derived from a 3,3',4,4'-biphenyltetracarboxylic acid compound. Examples of the 3,3',4,4'-biphenyltetracarboxylic acid compound include acid derivatives such as 3,3',4,4'-biphenyltetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), esters of 3,3',4,4'-biphenyltetracarboxylic acid, and salts.

[0032] The molar ratio of the structural unit (A1) to the structural unit (A2) is from 80 / 20 to 20 / 80, preferably from 70 / 30 to 30 / 70, and more preferably from 60 / 40 to 40 / 60. When the molar ratio of the structural unit (A1) to the structural unit (A2) is within this range, the melt fluidity is further improved.

[0033] The total proportion of the structural unit (A1) and the structural unit (A2) contained in the tetravalent residue (A') is 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Thereby, the melt fluidity is further improved. The total proportion of the structural unit (A1) and the structural unit (A2) contained in the tetravalent residue (A') is 100 mol% or less, and may be 95 mol% or less.

[0034] The tetravalent residue (A') may contain a structural unit derived from an aromatic tetracarboxylic acid other than a pyromellitic acid compound and a 3,3',4,4'-biphenyltetracarboxylic acid compound. Examples of other aromatic tetracarboxylic acids include 3,3',4,4'-benzophenonetetracarboxylic acid compounds, 2,3,3',4'-benzophenonetetracarboxylic acid compounds, 2,3,3',4'-biphenyltetracarboxylic acid compounds, 2,2',3,3'-biphenyltetracarboxylic acid compounds, 4,4'-sulfonyldiphthalic acid compounds, 4,4'-thiodiphthalic acid compounds, 4,4'-oxydiphthalic acid compounds, 3,4'-oxydiphthalic acid compounds, 4,4'-isopropylidenediphthalic acid compounds, 4,4'-(hexafluoroisopropylidene)diphthalic acid compounds, 4,4'-[1,4-phenylenebis(oxy)]diphthalic acid compounds, 4,4'-[1,3-phenylenebis(oxy)]diphthalic acid compounds, 1,4,5,8-naphthalenetetracarboxylic acid compounds, 2,3,6,7-naphthalenetetracarboxylic acid compounds, 2,3,6,7-anthracenetetracarboxylic acid compounds, 3,4,9,10-perylenetetracarboxylic acid compounds, 1,2,3,4-benzenetetracarboxylic acid compounds, 9,9-bis(3,4-dicarboxyphenyl)fluorene compounds, and the like. These may be used alone or in combination of two or more.

[0035] <1-2. Aromatic diamine (B)> The amic acid oligomer contains a divalent residue (B') derived from an aromatic diamine (B). The divalent residue (B') contains at least a structural unit (B1).

[0036] The structural unit (B1) can be derived from, for example, the following aromatic diamines (B). X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a direct bond include 2,2'-dimethylbenzidine, 3,3'-dimethylbenzidine, 3,3',5,5'-tetramethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a methylene group include 3,3'-diaminodiphenylmethane, and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is an ether group include 3,3'-diaminodiphenyl ether (3,3'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), 2,4'-diaminodiphenyl ether (2,4'-ODA), 2,3'-diaminodiphenyl ether (2,3'-ODA), 2,2'-diaminodiphenyl ether (2,2'-ODA), and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a carbonyl group include 3,3'-diaminobenzophenone, and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a sulfonyl group include 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a sulfide group include 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is an amide group include 4-amino-N-(3-aminophenyl)benzamide, 3-amino-N-(3-aminophenyl)benzamide, and the like. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is an ester group include 4-aminophenyl-3-aminobenzoate, 3-aminophenyl-4-aminobenzoate, 3-aminophenyl-3-aminobenzoate, and the like. X in formula (4) 1Examples of the aromatic diamine (B) in which X is an isopropylidene group include 2,2-bis(3-aminophenyl)propane. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a hexafluoroisopropylidene group include 2,2-bis[4-(3-aminophenoxy)phenyl]hexafluoropropane. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a 9,9-fluorenylidene group include 9,9-bis(3-aminophenyl)fluorene. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is an m-phenylenedioxy group include 1,3-bis(3-aminophenoxy)benzene. X in formula (4) 1 Examples of the aromatic diamine (B) in which X is a p-phenylenedioxy group include 1,4-bis(3-aminophenoxy)benzene. These aromatic diamines (B) that provide the structural unit (B1) may be substituted by an aryl group or a halogenated aryl group.

[0037] Among them, from the viewpoints of the solubility of the amic acid oligomer and the imide oligomer obtained from the amic acid oligomer in a solvent, the moldability of the amic acid oligomer and the imide oligomer obtained from the amic acid oligomer, and the flexibility of the cured product, the structural unit (B1) preferably has an asymmetric and non-planar structure. For example, the structural unit (B1) is preferably a structural unit derived from 3,4'-diaminodiphenyl ether (3,4'-ODA).

[0038] The divalent residue (B') may further contain a structural unit (B2). The structural unit (B2) is a divalent residue derived from 1,3-diaminobenzene.

[0039] The molar ratio of the structural unit (B1) to the structural unit (B2) is from 100 / 0 to 20 / 80, preferably from 90 / 10 to 30 / 70, and more preferably from 80 / 20 to 40 / 60. When the molar ratio of the structural unit (B1) to the structural unit (B2) is within this range, the heat resistance and mechanical properties of the resulting cured product can be improved.

[0040] The total proportion of the structural unit (B1) and the structural unit (B2) contained in the divalent residue (B’) is 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Thereby, the heat resistance and mechanical properties of the obtained cured product are further improved. The total proportion of the structural unit (B1) and the structural unit (B2) contained in the divalent residue (B’) is 100 mol% or less, and may be 95 mol% or less.

[0041] The divalent residue (B’) may contain, in addition to the structural unit (B1) and the structural unit (B2), a structural unit derived from another aromatic diamine. Examples of the other aromatic diamines include 1,4-diaminobenzene, 1,2-diaminobenzene, 4,6-diethyl-2-methyl-1,3-diaminobenzene, 2,6-diaminotoluene, 2,6-diethyl-1,3-diaminobenzene, 2,5-diaminotoluene, 2,4-diaminotoluene, 4,4’-diaminodiphenylmethane, bis(2,6-diethyl-4-aminophenyl)methane, 2,2-bis(4-aminophenyl)propane, bis(2-ethyl-6-methyl-4-aminophenyl)methane, 4,4’-methylene-bis(2-ethyl-6-methylaniline), 4,4’-methylene-bis(2,6-diethylaniline), 4,4’-diaminooctafluorobiphenyl, 4,4’-diaminobenzophenone, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4,4’-diaminodiphenyl ether (4,4’-ODA), 4,4’-bis(3-aminophenoxy)biphenyl, 4,4’-bis(4-aminophenoxy)biphenyl, etc. These may be used alone or in combination of two or more.

[0042] <1-3. End-capping agent> The amic acid oligomer contains, at its terminals, a structural unit selected from the group consisting of the structural unit (C) represented by the formula (6) and the structural unit derived from the aromatic diamine (B). That is, both terminals of the amic acid oligomer may be the structural unit (C), or one terminal of the amic acid oligomer may be the structural unit (C) and the other terminal may be the structural unit derived from the aromatic diamine (B). "The terminal is the structural unit derived from the aromatic diamine (B)" means a state where "-NH 2 " derived from the diamine constituting Y is at the terminal.

[0043] The structural unit (C) is derived from a terminal capping agent containing a phenylethynyl group. As the terminal capping agent containing a phenylethynyl group, it is preferable to use a 4-(2-phenylethynyl)phthalic acid compound. Examples of the 4-(2-phenylethynyl)phthalic acid compound include 4-(2-phenylethynyl)phthalic acid, 4-(2-phenylethynyl)phthalic anhydride (PEPA), acid derivatives such as esters or salts of 4-(2-phenylethynyl)phthalic acid. By using the 4-(2-phenylethynyl)phthalic acid compound, the resulting cured product exhibits excellent heat resistance and mechanical properties.

[0044] In 100 mol% of Z, the content of the structural unit (C) is 85 to 100 mol%, preferably 90 to 100 mol%, and more preferably 95 to 100 mol%. Thereby, the resulting cured product exhibits excellent heat resistance and mechanical properties. In this specification, the content of the structural unit (C) in 100 mol% of Z means the ratio of the structural unit (C) in 100 mol% of Z contained in the aggregate of the amic acid oligomer represented by the formula (1).

[0045] 〔2. Varnish〕 The varnish according to one embodiment of the present invention is obtained by dissolving the above-mentioned amino acid oligomer in a solvent having a boiling point of 135°C or lower. If the boiling point of the solvent is 135°C or lower, it is easy to remove the solvent. Preferably, the boiling point of the solvent is 125°C or lower. Also, preferably, the boiling point of the solvent is 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. If the boiling point of the solvent is 80°C or higher, when handling the prepreg prepared by impregnating the fiber-reinforced material with the varnish of the amino acid oligomer near room temperature, the solvent is less likely to volatilize and the tackiness is maintained for a long time. Note that the description regarding the range of the boiling point of the solvent in this specification is intended to mean that the boiling points of all solvents contained in the mixed solvent are within the above range when the solvent is a mixed solvent.

[0046] Examples of the solvent include at least one solvent selected from the group consisting of a mixed solvent of an alcohol-based solvent and an ether-based solvent, a single solvent of a hydroxyether-based solvent, a mixed solvent of an alcohol-based solvent and a hydroxyether-based solvent, a mixed solvent of an ether-based solvent and a hydroxyether-based solvent, and a mixed solvent of an alcohol-based solvent, an ether-based solvent, and a hydroxyether-based solvent. With these solvents, the above-mentioned amino acid oligomer can be stably dissolved. Among them, the solvent is preferably a single solvent of a hydroxyether-based solvent or a mixed solvent of an ether-based solvent and a hydroxyether-based solvent.

[0047] In this specification, the "single solvent of a hydroxyether-based solvent" refers to a solvent composed only of a hydroxyether-based solvent. The single solvent of a hydroxyether-based solvent may consist of only one type of hydroxyether-based solvent or may contain a plurality of types of hydroxyether-based solvents.

[0048] The hydroxyl groups possessed by alcohol molecules and hydroxyether molecules stabilize radicals that may be formed from ether solvents, for example, during auto-oxidation by oxygen. Therefore, it becomes difficult to generate peroxides when obtaining an amic acid oligomer. That is, alcohol solvents and hydroxyether solvents also function as stabilizers for ether solvents. Unlike ether solvents, the above-mentioned hydroxyether solvents have the function of self-stabilization even when used as a single solvent. However, for further stabilization, the hydroxyether solvent may be mixed with an alcohol solvent.

[0049] It is preferable that the alcohol molecules, ether molecules, and / or hydroxyether molecules contained in the solvent have two or more oxygen atoms per molecule. A solvent containing such molecules has a high ability to dissolve amic acid oligomers.

[0050] Examples of alcohol solvents include methanol (boiling point 65 °C), ethanol (boiling point 78 °C), 1-propanol (boiling point 98 °C), 2-propanol (boiling point 82 °C), etc. Examples of ether solvents include 1,3-dioxane (boiling point 105 °C), 1,4-dioxane (boiling point 101 °C), tetrahydrofuran (boiling point 66 °C), 1,3-dioxolane (boiling point 75 °C), 1,2-dimethoxyethane (boiling point 83 °C), etc. Examples of hydroxyether solvents include methoxymethanol (boiling point 90 - 95 °C), ethoxymethanol (boiling point 102 °C), 2-methoxyethanol (boiling point 124 °C), 2-ethoxyethanol (boiling point 135 °C), 1-methoxy-2-propanol (boiling point 119 °C), etc. These may be used alone or in combination of two or more.

[0051] 〔3. Method for producing amic acid oligomer〕 The method for producing an amic acid oligomer according to an embodiment of the present invention is not particularly limited and can be obtained using any method. An example thereof will be described below.

[0052] The above-mentioned amino acid oligomers are obtained by mixing and heating aromatic tetracarboxylic acids, aromatic diamines, and a terminal capping agent containing a phenylethynyl group. For example, an aromatic tetracarboxylic dianhydride, an aromatic diamine, and 4-(2-phenylethynyl)phthalic anhydride are used such that the total amount of acid anhydride groups and the total amount of amino groups of all components are approximately equal. By reacting these components in a solvent at a temperature of about 100°C or lower, particularly 80°C or lower, amino acid oligomers can be produced.

[0053] As a particularly preferred production method of the above-mentioned amino acid oligomers, for example, the following method can be mentioned. First, an aromatic diamine is uniformly dissolved in a solvent, and then an aromatic tetracarboxylic dianhydride is added to the solution and reacted at about 5 to 60°C while being uniformly dissolved. Then, 4-(2-phenylethynyl)phthalic anhydride as a terminal capping agent is further added to the solution and reacted at about 5 to 60°C to produce the above-mentioned amino acid oligomers. In the above reaction, it is preferable to carry out all reaction steps or some of the reaction steps in an atmosphere of an inert gas such as nitrogen gas or argon gas or in a vacuum.

[0054] The solvent used for the production of amino acid oligomers can be the solvents exemplified in the above [2. Varnish].

[0055] 〔4. Imide oligomers〕 The imide oligomer according to one embodiment of the present invention is obtained from the above-described amino acid oligomer. For example, the above-described amino acid oligomer can be dehydrated and cyclized to obtain an imide oligomer by a method of adding a chemical imidizing agent at about 0 to 140°C or a method of heating to a high temperature of 140 to 275°C. For example, by heating the solution containing the above-described amino acid oligomer or the solid of the amino acid oligomer obtained by removing the solvent from the solution of the amino acid oligomer at 140 to 275°C for 5 minutes to 24 hours, the amino acid oligomer can be subjected to an imidization reaction, and as a result, an imide oligomer can be obtained. In the above reaction, it is preferable to perform all or a part of the reaction steps in an atmosphere of an inert gas such as nitrogen gas or argon gas or in a vacuum.

[0056] 〔5. Prepreg and semi-prepreg〕 The prepreg or semi-prepreg according to one embodiment of the present invention is obtained by heat-fusing or impregnating the above-described amino acid oligomer, varnish or imide oligomer to reinforcing fibers. As used herein, the semi-prepreg means a resin (for example, an amino acid oligomer or an imide oligomer)-reinforcing fiber composite in which the resin is partially impregnated (semi-impregnated state) into the reinforcing fibers and integrated. The semi-prepreg can also be obtained by mixing the powder of the imide oligomer with the reinforcing fibers. Further, a prepreg can be obtained from the semi-prepreg. For example, by further heating and melting the semi-prepreg and impregnating the resin into the reinforcing fibers, a prepreg can be obtained.

[0057] The prepreg is obtained by impregnating the reinforcing fibers with the varnish and, if necessary, evaporating and removing a part of the solvent by heating or the like. For example, a varnish of an amino acid oligomer having an appropriately adjusted concentration is impregnated into, for example, reinforcing fibers or a reinforcing fiber fabric aligned in one direction in a planar shape, and dried in a dryer at 20 to 180°C for 1 minute to 20 hours to obtain a prepreg. Further, as the varnish, an imide oligomer solution obtained by dissolving a powdery imide oligomer in a solvent may be used.

[0058] The resin content adhering to the reinforcing fiber or the reinforcing fiber fabric is preferably 10 to 60% by weight, more preferably 20 to 50% by weight. In this specification, the resin content means the ratio of the weight of the resin to the total weight of the resin and the weight of the reinforcing fiber or the reinforcing fiber fabric.

[0059] Also, the amount of the solvent adhering to the reinforcing fiber or the reinforcing fiber fabric is preferably 1 to 30% by weight, more preferably 5 to 25% by weight, and even more preferably 5 to 20% by weight with respect to the total weight of the prepreg. If the amount of the solvent adhering to the reinforcing fiber or the reinforcing fiber fabric is within the above range, the handling during the lamination of the prepreg can be facilitated. Further, by preventing the resin from flowing out during the molding process of the fiber-reinforced composite material at a high temperature, a fiber-reinforced composite material exhibiting excellent mechanical strength can be produced.

[0060] Examples of the reinforcing fiber include inorganic fibers such as carbon fiber, glass fiber, metal fiber, and ceramic fiber, and organic synthetic fibers such as polyamide fiber, polyester-based fiber, polyolefin-based fiber, and novoloid fiber. These reinforcing fibers can be used alone or in combination of two or more.

[0061] In particular, in order to exhibit excellent mechanical properties and high heat resistance in the fiber-reinforced composite material produced from the prepreg, the reinforcing fiber is preferably carbon fiber. The carbon fiber is not particularly limited as long as it is a material having a continuous fiber shape with a carbon content in the range of 85 to 100% by weight and having at least a partially graphite structure. Examples of such carbon fibers include carbon fibers such as polyacrylonitrile (PAN)-based, rayon-based, lignin-based, and pitch-based carbon fibers. Among these, carbon fibers such as PAN-based or pitch-based are preferred because they are general-purpose, inexpensive, and have high strength.

[0062] Generally, carbon fibers are sized. These carbon fibers may be used as they are. If necessary, carbon fibers with a small amount of sizing agent may be used. Alternatively, the sizing agent can also be removed from the carbon fibers by existing methods such as organic solvent treatment or heat treatment.

[0063] The amount of sizing agent used is preferably 0.5% by weight or less, more preferably 0.2% by weight or less, based on the carbon fibers. Usually, since the sizing agent used for carbon fibers is for epoxy resins, it may decompose at a temperature of 280 °C or higher for curing the imide oligomer. By setting the amount of sizing agent used within the above range, a high-quality fiber-reinforced composite material with reduced defects (voids) caused by the volatilization of decomposition products of the sizing agent can be obtained.

[0064] Also, the fiber bundles of carbon fibers may be opened in advance using air or a roller or the like. Thereby, the resin or resin solution can be impregnated between the single filaments of the carbon fibers. By opening the fibers, the impregnation distance of the resin is shortened, and it becomes easier to obtain a fiber-reinforced composite material with reduced or no defects such as voids.

[0065] Examples of the form of the reinforcing fiber material constituting the prepreg include structures such as UD (unidirectional material), woven fabrics (plain weave, twill weave, satin weave, etc.), knitted fabrics, braided fabrics, and non-woven fabrics, and are not particularly limited. The form of the reinforcing fiber material may be appropriately selected according to the purpose, and these can be used alone or in combination.

[0066] The obtained prepreg is preferably stored or transported in a state where one or each of both sides thereof is covered with a resin sheet such as polyethylene terephthalate (PET) or a coating sheet such as paper. Such a prepreg in a covered state is stored and transported in a roll state or a sheet state cut out from a roll.

[0067] 〔6. Cured Product〕 The cured product according to one embodiment of the present invention is obtained by heat-curing the above-mentioned amino acid oligomer, varnish or imide oligomer. When the above-mentioned amino acid oligomer, varnish or imide oligomer is heated, the residue of the 4-(2-phenylethynyl)phthalic acid compound at the terminal of the amino acid oligomer or imide oligomer reacts with other molecules to form a high molecular weight. At the same time, the amino acid oligomer or imide oligomer is cured. In this reaction, it is considered that the triple bond of the residue of the 4-(2-phenylethynyl)phthalic acid compound, as well as the double bond and single bond derived from the triple bond, are involved. Therefore, the structure of the amino acid oligomer or imide oligomer contained in the cured product after the reaction becomes very complex.

[0068] The shape of the cured product is not particularly limited and may be formed into a desired shape by any method. Examples of the shape of the cured product include a state that is two-dimensionally or three-dimensionally formed, such as a film, a sheet, a rectangular parallelepiped shape or a rod shape. For example, the varnish is applied to a support, and then heat-cured at 260 to 500 ° C for 5 to 200 minutes to obtain a cured product formed into a film shape. Alternatively, a cured product formed into a film shape may be obtained by hot pressing a powder of the imide oligomer. That is, one embodiment of the present invention also includes a film (a cured product in a film shape) obtained from the cured product.

[0069] Further, the powdery imide oligomer may be filled into a mold such as a die, and a preform may be formed by compression molding at 10 to 330 ° C and 0.1 to 100 MPa for about 1 second to 100 minutes. A cured product can also be obtained by heating this preform at 280 to 500 ° C for about 10 minutes to 40 hours. Note that all the pressure values in this specification are the actual pressure values applied to the sample.

[0070] The glass transition temperature (Tg) of the cured product is preferably 250°C or higher, more preferably 290°C or higher, and even more preferably 310°C or higher. The tensile modulus of the cured product is preferably 2.60 GPa or higher, more preferably 2.90 GPa or higher, and even more preferably 3.00 GPa or higher. The tensile strength at break of the cured product is preferably 110 MPa or higher, more preferably 120 MPa or higher. The elongation at break of the cured product is preferably 5.0% or higher, more preferably 7.0% or higher, and even more preferably 9.0% or higher. In this specification, the glass transition temperature (Tg), tensile modulus, tensile strength at break, and elongation at break are intended to be those measured by the methods described in the examples below.

[0071] Further, the cured product may further contain reinforcing fibers. The cured product containing such reinforcing fibers may be a fiber-reinforced composite material obtained by laminating the prepreg and heating and curing it. Alternatively, the cured product may be a fiber-reinforced composite material obtained by laminating a semi-prepreg and / or prepreg produced through a fusion step of the imide oligomer after attaching the powder of the imide oligomer to the fibers and then heating and curing.

[0072] The prepreg is cut into a desired size, stacked in a predetermined number of layers, and heated and cured at a temperature of 280 to 500°C and a pressure of 0.1 to 100 MPa for about 10 minutes to 40 hours using an autoclave or a hot press, etc., to obtain a fiber-reinforced composite material. If necessary before the heat curing, the prepreg stacked in a predetermined number of layers may be heated and dried at 200 to 310°C under normal pressure or reduced pressure for about 5 minutes to 40 hours. Also, after attaching the powder of the imide oligomer to the reinforcing fibers, a fiber-reinforced composite material can be obtained as a laminated plate heat-cured in the same manner as above by laminating a semi-prepreg and / or prepreg produced through a fusion step of the imide oligomer.

[0073] Further, the fiber-reinforced composite material preferably has a glass transition temperature (Tg) of 300°C or higher, more preferably 310°C or higher.

[0074] Alternatively, a molded body of a film-shaped imide oligomer, a powder of an imide oligomer, a semi-preg or a prepreg may be inserted between a fiber-reinforced composite material and a different material or the same material, and heated and melted to be integrated to obtain a fiber-reinforced composite material structure. Here, the different material is not particularly limited, and any of those commonly used in this field can be used. Examples include metal materials having a honeycomb shape and core materials having a sponge shape.

[0075] 〔7. Applications〕 The amino acid oligomer, varnish, imide oligomer, semi-preg, prepreg, their cured products, and fiber-reinforced composite materials can be used in a wide range of fields that require easy moldability and high heat resistance, including general industrial applications. Such fields include aircraft, space industry equipment, vehicle engine (peripheral) members, transport arms, robot arms, roll materials, friction materials, sliding members such as bearings, etc. In the case of aircraft members, examples include engine fan cases, inner frames, moving blades (such as fan blades), stationary blades (such as structural guide vanes (SGV)), bypass ducts, and various pipes. In the case of vehicle members, brake members, engine members (such as cylinders, motor cases, air boxes), and energy regeneration system members are preferably mentioned.

[0076] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Examples

[0077] Examples and comparative examples for explaining one embodiment of the present invention are shown below, but these do not limit the present invention. First, the measurement conditions for each physical property were as follows.

[0078] 〔Test Method〕 (1) Glass transition temperature (Tg) Regarding the cured product, a storage modulus curve was measured under an air atmosphere using an RSA3 type dynamic viscoelasticity measuring device (DMA, manufactured by TA Instruments) in a tensile mode, with a strain of 0.3%, a frequency of 1 Hz, and a heating rate of 5 °C / min. Tangents were drawn to the storage modulus curve before and after the inflection point of the obtained storage modulus curve. The temperature at the intersection of the tangents was defined as the glass transition temperature of the cured product.

[0079] (2) Tensile modulus, tensile strength at break, and elongation at break of the cured product Regarding the cured product, a tensile test was carried out using a tensile tester TENSILON / UTM-II-20 (manufactured by Orientec). The test temperature was room temperature, the tensile speed was 5 mm / min, and the test piece shape was 30 mm in length and 3 mm in width.

[0080] 〔Raw material compounds〕 In the following Examples and Comparative Examples, each raw material compound and solvent are indicated by the following notations.

[0081] <(Component (A): Aromatic tetracarboxylic acids)> PMDA: 1,2,4,5-benzenetetracarboxylic dianhydride (literature value of melting point: 286 °C) s-BPDA: 3,3’,4,4’-biphenyltetracarboxylic dianhydride (literature value of melting point: 303 °C) <(Component (B): Aromatic diamines)> 3,4’-ODA: 3,4’-diaminodiphenyl ether (literature value of melting point: 67 - 71 °C) 1,3-DAB: 1,3-diaminobenzene (literature value of melting point: 63 - 67 °C) 4,4’-ODA: 4,4’-diaminodiphenyl ether (literature value of melting point: 190 - 1 94 °C) <(Component (C))> PEPA: 4-(2-phenylethynyl)phthalic anhydride (literature value of melting point: 149 - 154 °C) <(Solvent)> 2-ME: 2-methoxyethanol 〔Example 1〕 A 140 mL mayonnaise bottle equipped with a stirrer (a glass container, the same applies hereinafter) was charged with 4.5900 g (0.02292 mol) of 3,4’-ODA, which is component (B), and 32.3797 g of 2-ME, which is a solvent. Subsequently, the raw materials in the bottle were stirred at 20 °C to obtain a solution in which component (B) was uniformly dissolved. Next, 2.0003 g (0.00917 mol) of PMDA and 2.6978 g (0.00917 mol) of s-BPDA, which are component (A), and 9.2519 g of 2-ME were added to the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 60 °C for 15 minutes until component (A) was completely dissolved to obtain a uniform solution. Further, 2.2763 g (0.00917 mol) of PEPA, which is component (C), and 4.6247 g of 2-ME were added to the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 20 °C for 3 hours to obtain a solution in which the amic acid oligomer was uniformly dissolved. Hereinafter, this solution will be referred to as an amic acid oligomer solution. Incidentally, the content of structural unit (C) in 100 mol% of Z100 in formula (1) was 100 mol%.

[0082] Subsequently, the amic acid oligomer solution was transferred to a metal bath. Next, the bath was placed in a vacuum dryer and dried under vacuum at 45 °C overnight to remove 2-ME. Thereby, a solid of the amic acid oligomer was obtained. The solid of the amic acid oligomer was finely pulverized to form a powder. Thereafter, the powder of the amic acid oligomer was heated in an oven at 260 °C for 1 hour in an air atmosphere to imidize it, thereby obtaining a solid of the imide oligomer. The solid of the imide oligomer was finely pulverized to form a powder. The obtained powder of the imide oligomer was heated at 370 °C for 1 hour using a hot press to melt and cure the imide oligomer, thereby obtaining a cured product in the form of a film. The thickness of the obtained film was about 0.13 mm. The degree of polymerization n of the amic acid oligomer and the imide oligomer set from the addition amounts of the respective components and the reaction conditions was 4. The setting of this degree of polymerization is the same in the following Examples and Comparative Examples. The properties of the cured product in the form of a film of the imide oligomer are shown in Table 1.

[0083] [Comparative Example 1] Into a 140 mL mayonnaise bottle equipped with a stirrer, 4.5901 g (0.02292 mol) of 3,4'-ODA, which is component (B), and 30.4257 g of 2-ME, which is a solvent, were added. Subsequently, the raw materials in the bottle were stirred at 22 °C to obtain a solution in which component (B) was uniformly dissolved. Next, 4.0000 g (0.01834 mol) of PMDA, which is component (A), and 8.6931 g of 2-ME were added into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 50 °C for 2 hours until component (A) was completely dissolved to obtain a uniform solution. Further, 2.2763 g (0.00917 mol) of PEPA, which is component (C), and 4.3463 g of 2-ME were added into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 70 °C for 4 hours to obtain an amic acid oligomer solution. Incidentally, the content of structural unit (C) in 100 mol% of Z1 in formula (1) was 100 mol%.

[0084] Subsequently, from this amic acid oligomer solution, a powder of the amic acid oligomer was obtained in the same manner as in Example 1. Also, from this powder of the amic acid oligomer, a powder of the imide oligomer was obtained in the same manner as in Example 1. The obtained powder of the imide oligomer was heated at 370 °C for 1 hour using a hot press, but the powder did not melt sufficiently and a cured product in film form could not be obtained.

[0085] [Example 2] Into a 140 mL mayonnaise bottle equipped with a stirrer, 2.2950 g (0.01146 mol) of 3,4'-ODA, which is component (B), 1.2395 g (0.01146 mol) of 1,3-DAB, and 29.4237 g of 2-ME, which is a solvent, were charged. Subsequently, the raw materials in the bottle were stirred at 20 °C to obtain a solution in which component (B) was uniformly dissolved. Next, 2.0000 g (0.00917 mol) of PMDA, which is component (A), 2.6979 g (0.00917 mol) of s-BPDA, and 8.4067 g of 2-ME were charged into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 20 °C for 1 hour and 40 minutes until component (A) was completely dissolved to obtain a uniform solution. Further, 2.2763 g (0.00917 mol) of PEPA, which is component (C), and 4.2033 g of 2-ME were charged into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 20 °C for 2 hours and 30 minutes to obtain an amic acid oligomer solution. The content of structural unit (C) in 100 mol% of Z100 in formula (1) was 100 mol%.

[0086] Subsequently, from this amic acid oligomer solution, a powder of the amic acid oligomer was obtained in the same manner as in Example 1. Also, from the powder of this amic acid oligomer, a powder of the imide oligomer was obtained in the same manner as in Example 1. The obtained powder of the imide oligomer was heated at 370 °C for 1 hour using a hot press to melt and cure the imide oligomer, and a cured product in film form was obtained. The thickness of the obtained film was about 0.09 mm. The properties of the cured product in film form of the imide oligomer are shown in Table 1.

[0087] [Comparative Example 2] Into a 140 mL mayonnaise bottle equipped with a stir bar, 2.2951 g (0.01146 mol) of 3,4'-ODA, which is component (B), 1.2395 g (0.01146 mol) of 1,3-DAB, and 27.4672 g of 2-ME, which is a solvent, were added. Subsequently, the raw materials in the bottle were stirred at 20 °C to obtain a solution in which component (B) was uniformly dissolved. Next, 4.0000 g (0.01834 mol) of PMDA, which is component (A), and 7.8486 g of 2-ME were added into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 20 °C for 30 minutes until component (A) was completely dissolved to obtain a uniform solution. Further, 2.2763 g (0.00917 mol) of PEPA, which is component (C), and 3.9242 g of 2-ME were added into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, the solution in the bottle was stirred at 20 °C for 3 hours to obtain an amic acid oligomer solution. Incidentally, the content of structural unit (C) in 100 mol% of Z100 mol% in formula (1) was 100 mol%.

[0088] Subsequently, from this amic acid oligomer solution, a powder of the amic acid oligomer was obtained in the same manner as in Example 1. Further, from this powder of the amic acid oligomer, a powder of the imide oligomer was obtained in the same manner as in Example 1. The obtained powder of the imide oligomer was heated at 370 °C for 1 hour using a hot press, but the powder did not melt sufficiently and a cured product in film form could not be obtained.

[0089] [Comparative Example 3] Into a 140 mL mayonnaise bottle equipped with a stir bar, 4.5901 g (0.02292 mol) of 4,4'-ODA, which is component (B), and 30.4259 g of 2-ME, which is a solvent, were added. Subsequently, the raw materials in the bottle were stirred at 70 °C to obtain a solution in which component (B) was uniformly dissolved. Next, 4.0001 g (0.01834 mol) of PMDA, which is component (A), and 8.6930 g of 2-ME were added into the bottle. Subsequently, the bottle was sealed with nitrogen. Thereafter, when stirred at 50 °C, precipitation of insoluble matter was observed, and it became difficult to stir further and the reaction could not be carried out. Therefore, the addition of PEPA was not achieved.

[0090] [Table 1]

[0091] 〔Results Explanation〕 In Example 1 using PMDA and s-BPDA as component (A), 3,4'-ODA as component (B), and PEPA as component (C), the moldability of the cured product (melt fluidity at high temperature) was superior to that of Comparative Example 1 using only PMDA as component (A). Also, in Example 2 using PMDA and s-BPDA as component (A), 3,4'-ODA and 1,3-DAB as component (B), and PEPA as component (C), the moldability of the cured product (melt fluidity at high temperature) was superior to that of Comparative Example 2 using only PMDA as component (A). From these facts, it can be understood that using PMDA and s-BPDA in combination as component (A) is essential in one embodiment of the present invention.

[0092] In Example 2 using PMDA and s-BPDA as component (A), 3,4'-ODA and 1,3-DAB as component (B), and PEPA as component (C), the glass transition temperature (Tg), tensile fracture strength, and tensile fracture elongation were improved compared to Example 1 using only 3,4'-ODA as component (B). From this fact, it is preferable to use 3,4'-ODA and 1,3-DAB in combination as component (B) from the viewpoints of the glass transition temperature (Tg) and mechanical properties of the cured product.

[0093] Note that in Comparative Example 3 using 4,4'-ODA (corresponding to the diamine in which R 3 and R 8 simultaneously represent a direct bond with the nitrogen atom in the amide bond with the acid anhydride component) not corresponding to either structural unit (B1) or structural unit (B2) in component (B) at 50 mol% or more, an amic acid oligomer solution could not be obtained. From this fact, it can be understood that using structural units (B1) and (B2) in a total amount of 50 mol% or more as component (B) is essential in one embodiment of the present invention.

Industrial Applicability

[0094] One embodiment of the present invention can be used in a wide range of fields that require easy formability and high heat resistance, such as aircraft, aerospace industry equipment, general industrial applications, and engine (peripheral) members for vehicles.

Claims

1. An amic acid oligomer represented by the following formula (1): 【Chemistry 1】 [In formula (1), n is an integer of 1≦n≦100; Q represents a tetravalent residue (A') derived from an aromatic tetracarboxylic acid (A); Here, the tetravalent residue (A') contains a structural unit (A1) represented by formula (2) and a structural unit (A2) represented by formula (3), 【Chemistry 2】 the molar ratio of the structural unit (A1) to the structural unit (A2) is in the range of 80 / 20 to 20 / 80; The tetravalent residue (A') contains the structural units (A1) and (A2) in a total amount of 90 mol % or more, Y represents a divalent residue (B') derived from an aromatic diamine (B); Here, the divalent residue (B') contains a structural unit (B1) represented by formula (4) and a structural unit (B2) represented by formula (5), 【Chemistry 3】 X １ represents a direct bond or a divalent linking group selected from the group consisting of a methylene group, an ether group, a carbonyl group, a sulfonyl group, a sulfide group, an amide group, an ester group, an isopropylidene group, a hexafluorinated isopropylidene group, a 9,9-fluorenylidene group, an m-phenylenedioxy group, and a p-phenylenedioxy group; (i) R １ ~R １０ None of R corresponds to an aryl group or a halogenated aryl group; １ ~R ５ any one of R represents a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxyl group, a carboxyl group, and an alkoxy group; and ６ ~R １０ one of the above represents a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxyl group, a carboxyl group, and an alkoxy group; (ii) R １ ~R ５ any one of represents one selected from the group consisting of an aryl group and a halogenated aryl group, any one of the others represents a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, and the remaining three each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxyl group, a carboxyl group, and an alkoxy group, and R ６ ~R １０ one of them represents a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxyl group, a carboxyl group, and an alkoxy group, or (iii) R １ ~R ５ any one of R represents a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, and the remaining four each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxyl group, a carboxyl group, and an alkoxy group; and ６ ~R １０ one of the above represents one selected from the group consisting of an aryl group and a halogenated aryl group, one of the others represents a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, and the remaining three each independently represent one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, a halogenated alkyl group, a hydroxyl group, a carboxyl group, and an alkoxy group, However, R ３ and R ８ and do not simultaneously represent a direct bond to a nitrogen atom in an amide bond with an acid anhydride component, the molar ratio of the structural unit (B1) to the structural unit (B2) is in the range of 80 / 20 to 40 / 60; The divalent residue (B') contains the structural unit (B1) and the structural unit (B2) in a total amount of 90 mol % or more, The divalent residue (B') contains, as the structural unit (B1), a structural unit derived from 3,4'-diaminodiphenyl ether, Z is a structural unit selected from the group consisting of a structural unit (C) represented by the following formula (6) and a structural unit derived from an aromatic diamine (B): 【Chemistry 4】 In 100 mol % of Z, the content of the structural unit (C) represented by the formula (6) is 85 mol % or more and 100 mol % or less.

2. A varnish obtained by dissolving the amic acid oligomer according to claim 1 in a solvent having a boiling point of 135° C. or lower.

3. 3. The varnish according to claim 2, wherein the solvent is at least one solvent selected from the group consisting of a mixed solvent of an alcohol-based solvent and an ether-based solvent, a single solvent of a hydroxyether-based solvent, a mixed solvent of an alcohol-based solvent and a hydroxyether-based solvent, a mixed solvent of an ether-based solvent and a hydroxyether-based solvent, and a mixed solvent of an alcohol-based solvent, an ether-based solvent and a hydroxyether-based solvent.

4. 4. The varnish according to claim 3, wherein the solvent is a hydroxyether solvent alone or a mixed solvent of an ether solvent and a hydroxyether solvent.

5. An imide oligomer obtained from the amic acid oligomer according to claim 1.

6. A cured product obtained by heat-curing the amic acid oligomer according to claim 1, the varnish according to any one of claims 2 to 4, or the imide oligomer according to claim 5.

7. The cured product according to claim 6 , further comprising reinforcing fibers.

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