Polyimide precursor composition

Abstract

A polyimide precursor composition comprising: a polyimide precursor containing 70 mol% or more of a repeating unit represented by general formula (1) relative to all repeating units, and an imidazole compound represented by general formula (2). (In formula (1), X 1 is a 4-valent group having at least one norbornane skeleton, R 1 and R 2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbons, or an alkylsilyl group having 3 to 9 carbons, in formula (2), L 1 and L 2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbons, a carboxyl group, and a hydroxyl group, and n is an integer of 1 to 4.)

Description

Technical Field

[0001] This invention relates to a polyimide precursor composition, a varnish, and a polyimide film. Background Technology

[0002] The diverse applications of polyimide resins in electrical / electronic components and other fields have been the subject of much research. For example, with the aim of reducing the weight and flexibility of devices, there is a desire to replace glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates, and research on polyimide films suitable as such plastic substrates is underway.

[0003] Polyimide films for this purpose aim for high transparency, high heat resistance, and low coefficient of linear expansion (CTE).

[0004] Furthermore, high strength is also being sought. To meet these requirements, alicyclic carboxylic acids, aromatic carboxylic acids, and aromatic diamines have been investigated as raw materials. Additionally, efforts are underway to add additives to the membrane to further enhance these properties.

[0005] For example, Patent Document 1 discloses a polyimide precursor comprising repeating units having alicyclic structures and aromatic rings, a polyimide precursor composition comprising a specific amount of imidazole compounds, and a polyimide film manufactured therefrom, with the aim of improving transparency, low phase difference, and mechanical properties.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2015 / 080158 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] As mentioned above, various properties can be improved by focusing on the raw materials. For example, tetracarboxylic acids with a norbornene backbone in alicyclic carboxylic acids contribute to improved transparency and heat resistance. Furthermore, p-phenylenediamine, as an aromatic diamine, not only contributes to heat resistance but also to increased strength. Therefore, efforts are made to incorporate them at high ratios, particularly in polyimide films formed from polyimides with excellent heat resistance and strength. However, their low solubility and polymerizability make high-ratio incorporation difficult.

[0011] The present invention was made in view of the following circumstances, and the object of the present invention is to provide a polyimide precursor composition, a varnish, and a polyimide film obtained using the polyimide precursor composition, which can be used to manufacture a film with excellent heat resistance and strength.

[0012] Solution for solving the problem

[0013] The inventors discovered that a composition comprising a polyimide precursor having a specific structural unit and a specific imidazole compound, a varnish containing the composition, and a polyimide film obtained using the varnish can solve the above-mentioned problems, thereby completing the invention.

[0014] That is, the present invention relates to the following [1] to

[13] .

[0015] [1] A polyimide precursor composition comprising: a polyimide precursor having more than 70 mol% of repeating units of the following general formula (1) relative to all repeating units, and an imidazole compound of the following general formula (2).

[0016]

[0017] (In formula (1), X) 1 R is a tetravalent group having at least one norbornene skeleton. 1 and R 2 Each is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, in formula (2), L 1 and L 2 Each group consists independently of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a carboxyl group, and a hydroxyl group, where n is an integer from 1 to 4.

[0018] [2] According to the polyimide precursor composition described in [1] above, wherein X in the aforementioned general formula (1) 1 It is selected from at least one of the group consisting of the tetravalent group shown in formula (3), the tetravalent group shown in formula (5), and the tetravalent group shown in formula (6).

[0019]

[0020] [3] According to the polyimide precursor composition described in [1] or [2] above, wherein X in the aforementioned general formula (1) 1 It is a tetravalent group as shown in formula (3).

[0021]

[0022] [4] The polyimide precursor composition according to any one of [1] to [3] above, wherein the imidazole compound represented by the above general formula (2) is at least one selected from the group consisting of 1-benzylimidazole and 1-benzyl-2-methylimidazole.

[0023] [5] The polyimide precursor composition according to any one of [1] to [4] above contains more than 90 mol% of the repeating unit shown in the above general formula (1) relative to all repeating units of the polyimide precursor.

[0024] [6] A varnish comprising the polyimide precursor composition described in any one of [1] to [5] above and an organic solvent.

[0025] [7] A polyimide film obtained by applying the varnish described in [6] above onto a support and heating it.

[0026] [8] A method for manufacturing a polyimide film, wherein the varnish described in [6] above is applied to a support and heated.

[0027] [9] A polyimide resin comprising, relative to all repeating units of the polyimide resin, more than 70 mol% of repeating units of the general formula (4).

[0028]

[0029] (In equation (4), X) 1 (It is a tetravalent group having at least one norbornene skeleton.)

[0030]

[10] According to the polyimide resin described above [9], wherein X in the aforementioned general formula (4) 1 It is selected from at least one of the group consisting of the tetravalent group shown in formula (3), the tetravalent group shown in formula (5), and the tetravalent group shown in formula (6).

[0031]

[0032]

[11] According to the polyimide resin described in [9] or

[10] above, wherein X in the aforementioned general formula (4) 1 It is a tetravalent group as shown in formula (3).

[0033]

[0034]

[12] A polyimide film comprising the polyimide resin described in any one of [9] to

[11] above.

[0035]

[13] The polyimide film according to [7] or

[12] above, wherein the thickness of the polyimide film is less than 20 μm.

[0036] The effects of the invention

[0037] According to the present invention, a polyimide precursor composition capable of producing a film with excellent heat resistance and strength, a varnish, and a polyimide film obtained using the polyimide precursor composition can be provided. Detailed Implementation

[0038] [Polyimide precursor composition]

[0039] The polyimide precursor composition of the present invention comprises: a polyimide precursor comprising more than 70 mol% of the repeating unit shown in general formula (1) below relative to all repeating units, and an imidazole compound shown in general formula (2) below.

[0040]

[0041] (In formula (1), X) 1 R is a tetravalent group having at least one norbornene skeleton. 1 and R 2 Each is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms. In formula (2), L 1 and L 2 Each group consists independently of a hydrogen atom, an alkyl group (1-6 carbon atoms), a carboxyl group, or a hydroxyl group, where n is an integer from 1 to 4.

[0042] By using the polyimide precursor composition of the present invention, polyimide films containing repeating units derived from tetracarboxylic acid and p-phenylenediamine having a norbornene backbone can be manufactured. The reasons for the excellent heat resistance and strength of the resulting polyimide films are not yet clear, but are considered as follows.

[0043] It is believed that the imidazole compounds containing large-volume substituents in the polyimide precursor compositions of the present invention simultaneously exhibit the effects of promoting thermal imidization and acting as plasticizers, thus enabling the manufacture of polyimide films containing the aforementioned repeating units that are difficult to manufacture under normal conditions.

[0044] It is further believed that aliphatic acid dianhydrides with norbornene skeletons form a rigid skeleton with highly linear p-phenylenediamine, thus exhibiting excellent heat resistance and strength.

[0045] <Polyimide precursor>

[0046] The polyimide precursor contained in the polyimide precursor composition of the present invention comprises more than 70 mol% of the repeating units shown in the following general formula (1) relative to all repeating units.

[0047]

[0048] (In formula (1), X) 1 R is a tetravalent group having at least one norbornene skeleton. 1 and R 2 Each of the following is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.

[0049] It should be noted that the “repeating unit” in the polyimide precursor composition refers to an ammonium acid unit, ammonium ester unit, or ammonium silyl ester unit comprising one structural unit derived from tetracarboxylic dianhydride and one structural unit derived from diamine.

[0050] In the aforementioned equation (1), X 1 It is a tetravalent group having at least one norbornene skeleton. X 1 The preferred embodiment is obtained by removing two dicarboxylic anhydride portions (four carboxyl groups) from a tetracarboxylic dianhydride that is the raw material derived from the tetracarboxylic dianhydride structural unit A as described later.

[0051] In the aforementioned general formula (1), X 1 More preferably, it is selected from at least one of the group consisting of the tetravalent group shown in formula (3), the tetravalent group shown in formula (5), and the tetravalent group shown in formula (6), and even more preferably, it is the tetravalent group shown in formula (3).

[0052]

[0053] Through X 1 The resulting membrane has excellent heat resistance and strength as shown in formula (3) with a tetravalent group.

[0054] (Composition of polyimide precursor)

[0055] As described above, the polyimide precursor contains repeating units represented by the aforementioned general formula (1). However, particularly from the viewpoints of improved heat resistance, increased strength, reduced yellowness, and improved transparency, the repeating units represented by the aforementioned formula (1) are 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more, relative to all the repeating units of the aforementioned polyimide precursor. There is no upper limit, but it is 100 mol% or less.

[0056] Without impairing the effects of the invention, the polyimide precursor may contain repeating units other than those shown in the aforementioned general formula (1).

[0057] As a repeating unit other than the repeating unit shown in the aforementioned general formula (1), it is preferably selected from at least one of the group consisting of the repeating unit shown in the following general formula (7) and the repeating unit shown in the following general formula (8).

[0058]

[0059] (In equation (7), X) 1 R is a tetravalent group having at least one norbornene skeleton. 1 and R 2Each is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, Y 2 It is a divalent aliphatic group, alicyclic group, aromatic group, or combination thereof with 4 to 39 carbon atoms, serving as a bonding group, and may have at least one selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-. Wherein, Y 2 It does not contain phenylene.

[0060] In equation (8), X 2 R is a tetravalent aliphatic group, alicyclic group, aromatic group, or combination thereof with 4 to 39 carbon atoms. As a bonding group, it may have at least one selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-. 1 and R 2 Each is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms. Wherein, X 2 It does not contain the norbornene skeleton.

[0061] The content of repeating units other than those shown in the aforementioned general formula (1) is 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, even more preferably 5 mol% or less, even more preferably 1 mol% or less, even more preferably 0 mol%, and even more preferably not included, relative to all repeating units of the aforementioned polyimide precursor.

[0062] <Structural Units of Polyimide Precursors>

[0063] The aforementioned polyimide precursor contains repeating units as shown in the aforementioned general formula (1), and the structural units constituting the precursor are described below.

[0064] The polyimide precursor has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine.

[0065] It should be noted that in the polyimide precursor, structural unit A and structural unit B form an amic acid structure.

[0066] The polyimide precursor of the present invention comprises repeating units represented by the aforementioned general formula (1), wherein,

[0067] Structural unit A comprises a structural unit (A1) derived from a tetracarboxylic acid dianhydride having at least one norbornene skeleton, and structural unit B comprises a structural unit (B1) derived from a compound represented by the following formula (b1).

[0068]

[0069] (Structural Unit A)

[0070] Structural unit A is a structural unit derived from tetracarboxylic dianhydride, including structural units (A1) derived from tetracarboxylic dianhydride having at least one norbornene skeleton.

[0071] By incorporating structural units derived from tetracarboxylic acid dianhydrides with a norbornene backbone, polyimide films with excellent heat resistance and strength can be obtained.

[0072] The ratio of structural units (A1) in structural unit A is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more. There is no particular upper limit to this ratio, but it is 100 mol% or less.

[0073] Examples of tetracarboxylic dianhydrides derived from a tetracarboxylic dianhydride having at least one norbornene skeleton include compounds shown in formula (a1), compounds shown in formula (a2), and compounds shown in formula (a3).

[0074]

[0075] The compound represented by formula (a1) is norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic acid dianhydride (CpODA). The compound represented by formula (a2) is 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride (BNBDA). The compound represented by formula (a3) ​​is decahydro-1H,3H-4,10:5,9-dimethylbridgednaphthalene[2,3-c:6,7-c']difuran-1,3,6,8-tetraone (DNDA).

[0076] Among them, the compound represented by the preferred formula (a1) preferably contains structural unit A (A1) derived from the compound represented by the preferred formula (a1).

[0077] By setting the structural unit (A1) of the compound represented by formula (a1) as the structural unit of the polyimide precursor, a polyimide precursor capable of manufacturing polyimide films with excellent heat resistance and strength can be obtained.

[0078] Structural unit A may include structural units other than those derived from tetracarboxylic dianhydrides having a norbornene skeleton. There are no particular limitations on such structural units, and examples include structural units derived from aromatic tetracarboxylic dianhydrides, structural units derived from alicyclic tetracarboxylic dianhydrides other than structural unit (A1), and structural units derived from aliphatic tetracarboxylic dianhydrides.

[0079] Examples of aromatic tetracarboxylic dianhydrides that impart structural units derived from aromatic tetracarboxylic dianhydrides include biphenyl tetracarboxylic dianhydride (BPDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 2,2',3,3'-benzophenone tetracarboxylic dianhydride.

[0080] Examples of alicyclic tetracarboxylic dianhydrides that provide structural units other than the structural unit (A1) derived from alicyclic tetracarboxylic dianhydrides include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and dicyclohexyltetracarboxylic dianhydride.

[0081] Examples of aliphatic tetracarboxylic dianhydrides that provide structural units derived from aliphatic tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydrides.

[0082] Structural unit A may optionally include one type of structural unit or two or more types of structural units.

[0083] It should be noted that, in this specification, aromatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing one or more alicyclic rings but not aromatic rings, and aliphatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride not containing either aromatic or alicyclic rings.

[0084] (Structural Unit B)

[0085] Structural unit B is a structural unit derived from diamine, containing structural units (B1) derived from the compound shown in formula (b1) below.

[0086]

[0087] By including structural unit (B1) in structural unit B, a polyimide precursor capable of manufacturing polyimide films with excellent heat resistance and strength can be obtained.

[0088] The ratio of structural unit (B1) in structural unit B is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more. There is no particular upper limit to this ratio, but it is 100 mol% or less.

[0089] Structural unit B may include structural units other than structural unit (B1). There are no particular limitations on such structural units, and examples include structural units derived from aromatic diamines, structural units derived from alicyclic diamines, and structural units derived from aliphatic diamines, other than structural unit (B1).

[0090] Examples of aromatic diamines that provide structural units other than structural unit (B1) derived from aromatic diamines include 2,2'-bis(trifluoromethyl)benzidine (TFMB), 3,5-diaminobenzoic acid (3,5-DABA), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4-aminophenyl 4-aminobenzoate (4-BAAB), p-phenylenediamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-dimethylbiphenyl-4,4'-diamine, and 4,4'-diaminobenzidine. The compounds include 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobenzoylaniline, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and 1,4-bis(4-aminophenoxy)benzene.

[0091] Examples of alicyclic diamines that impart structural units derived from alicyclic diamines include 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane.

[0092] Examples of aliphatic diamines that provide structural units derived from aliphatic diamines include ethylenediamine and hexamethylenediamine.

[0093] It should be noted that, in this specification, aromatic diamines refer to diamines containing one or more aromatic rings, alicyclic diamines refer to diamines containing one or more alicyclic rings but not aromatic rings, and aliphatic diamines refer to diamines that do not contain either aromatic or alicyclic rings.

[0094] Structural unit B may optionally contain one type of structural unit or two or more types of structural units.

[0095] (Method for manufacturing polyimide precursors)

[0096] The aforementioned polyimide precursor can be manufactured by any method, but it is preferred to manufacture it by the following manufacturing method.

[0097] As described above, the polyimide precursor contains repeating units (amido acids) represented by the aforementioned general formula (1).

[0098] Specifically, a preferred method is to obtain a polyimide precursor by reacting a tetracarboxylic acid component and a diamine component constituting a polyamic acid comprising a repeating unit shown in the aforementioned general formula (1).

[0099] The tetracarboxylic acid component used in this manufacturing method preferably includes a compound that imparts a structural unit (A1). However, without impairing the effects of the present invention, it may also include a tetracarboxylic acid component other than a compound that imparts a structural unit (A1).

[0100] The diamine component used in this manufacturing method preferably includes a compound that imparts structural unit (B1). However, without impairing the effects of the present invention, it may also include diamine components other than the compound that imparts structural unit (B1).

[0101] It should be noted that the amount of diamine relative to the tetracarboxylic acid component is preferably 0.9 to 1.1 moles.

[0102] There are no particular restrictions on the method by which the tetracarboxylic acid component reacts with the diamine component in this manufacturing method; known methods can be used.

[0103] As a specific reaction method, one can include adding a tetracarboxylic acid component, a diamine component, a solvent, and a capping agent as needed into a reactor, and stirring for 1 to 72 hours at a temperature of 0 to 120°C, preferably 5 to 80°C.

[0104] When reacting below 80°C, the molecular weight of the polyimide precursor does not change depending on the temperature process of polymerization, and the thermal imidization can be suppressed, thus enabling the stable production of polyamic acid, i.e., the polyimide precursor.

[0105] The above method can be used to obtain a polyimide precursor solution with a polyamic acid structure dissolved in a solvent.

[0106] The concentration of the polyimide precursor in the resulting solution is preferably 1 to 50% by mass, more preferably 3 to 35% by mass, and even more preferably 5 to 30% by mass.

[0107] From the viewpoint of the mechanical strength of the obtained polyimide film, the number-average molecular weight of the polyimide precursor obtained by the aforementioned manufacturing method is preferably 5,000 to 500,000. Furthermore, from the same viewpoint, the weight-average molecular weight (Mw) is preferably 10,000 to 800,000, more preferably 100,000 to 300,000.

[0108] Next, the raw materials used in this manufacturing method will be explained.

[0109] [Tetracarboxylic acid component]

[0110] For the tetracarboxylic acid component used as a raw material in this manufacturing method, the tetracarboxylic acid dianhydride described in the aforementioned (structural unit (A)) column is preferred. It should be noted that the tetracarboxylic acid dianhydride used as a tetracarboxylic acid component in this manufacturing method can be in any form of dianhydride, tetracarboxylic acid (free acid), or alkyl ester of tetracarboxylic acid, but dianhydride is preferred.

[0111] The tetracarboxylic acid component used as a raw material in this manufacturing method includes a tetracarboxylic acid dianhydride (a compound that imparts a structural unit (A1)) having at least one norbornene skeleton.

[0112] Examples of tetracarboxylic acid dianhydrides having at least one norbornene skeleton include compounds shown in formula (a1), formula (a2), and formula (a3), with the compound shown in formula (a1) being preferred.

[0113] The proportion of tetracarboxylic acid dianhydride (a compound that imparts a structural unit (A1)) having at least one norbornene skeleton in the tetracarboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more. There is no particular upper limit to this proportion, but it is 100 mol% or less.

[0114] Tetracarboxylic acid components may include tetracarboxylic acid components other than tetracarboxylic dianhydrides having a norbornene skeleton. There are no particular limitations on such tetracarboxylic acid components, and examples include aromatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides other than compounds that impart a structural unit (A1), and aliphatic tetracarboxylic dianhydrides.

[0115] As a specific example of a tetracarboxylic acid component other than a tetracarboxylic acid dianhydride with a norbornene skeleton, the tetracarboxylic acid dianhydride described in the aforementioned (structural unit (A)) column can be cited.

[0116] These tetracarboxylic dianhydrides can be used in one or more forms.

[0117] [Diamine component]

[0118] The diamine component used as a raw material in this manufacturing method includes the compound shown in formula (b1) above.

[0119] In this manufacturing method, the diamine used as a raw material is preferably the diamine described in the aforementioned (structural unit (B)) column. It should be noted that, in this manufacturing method, the diamine used as the diamine component can be any form of diamine or diisocyanate corresponding to diamine, but diamine is preferred.

[0120] The diamine component used as a raw material in this manufacturing method includes the compound shown in the aforementioned formula (b1) (a compound that imparts structural unit (B1)).

[0121] The proportion of the compound represented by the aforementioned formula (b1) (the compound that imparts the structural unit (B1)) in the diamine component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more. There is no particular upper limit to this proportion, but it is 100 mol% or less.

[0122] The diamine component may include diamine components other than those shown in the aforementioned formula (b1). There are no particular limitations on such diamine components, and examples include aromatic diamines, alicyclic diamines, and aliphatic diamines other than those that impart structural unit (B1).

[0123] As a specific example of a diamine component other than the compound shown in the aforementioned formula (b1), the diamine described in the aforementioned (structural unit (B)) column can be cited.

[0124] One type of diamine can be used, or two or more types can be used.

[0125] [End-capping agent]

[0126] In addition, in the manufacture of polyimide precursors, in addition to the aforementioned tetracarboxylic acid and diamine components, end-capping agents can also be used.

[0127] Monoamines or dicarboxylic acids are preferred as capping agents. The amount of capping agent introduced is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, relative to 1 mol of the tetracarboxylic acid component. Examples of monoamine capping agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, and 4-methylaniline. Among these, benzylamine and aniline are preferred. Dicarboxylic acids are preferred as capping agents, and a portion of them may be cyclically closed. Examples include phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid. Among them, phthalic acid and phthalic anhydride are preferred.

[0128] [solvent]

[0129] The solvent used in the manufacture of the aforementioned polyimide precursor only needs to be able to dissolve the generated polyimide precursor. Examples include aprotic solvents, phenolic solvents, ether solvents, and carbonate solvents.

[0130] Specific examples of aprotic solvents include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolinone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphoramide and tris(dimethylamino)phosphine; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methylcyclohexanone; and ester solvents such as (2-methoxy-1-methylethyl) acetate.

[0131] Specific examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol.

[0132] Specific examples of ether-based solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, and 1,4-dioxane.

[0133] Specific examples of carbonate-based solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate.

[0134] Among the above-mentioned reaction solvents, amide-based solvents or lactone-based solvents are preferred, amide-based solvents are more preferred, and N-methyl-2-pyrrolidone is even more preferred. The above-mentioned reaction solvents can be used alone or in combination of two or more.

[0135] <Imidazole compounds>

[0136] The polyimide precursor composition of the present invention comprises an imidazole compound represented by the following general formula (2).

[0137]

[0138] (In equation (2), L) 1 and L 2 Each group consists independently of a hydrogen atom, an alkyl group (1-6 carbon atoms), a carboxyl group, or a hydroxyl group, where n is an integer from 1 to 4.

[0139] By using imidazole compounds represented by the aforementioned general formula (2), polyimide films formed by incorporating a tetracarboxylic acid with a norbornene backbone as a tetracarboxylic acid moiety and p-phenylenediamine as a diamine moiety in a high ratio can be obtained efficiently. The resulting polyimide films exhibit excellent heat resistance and strength.

[0140] In equation (2), L 1 and L2 Each of the following is independently composed of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a carboxyl group, or a hydroxyl group, preferably at least one selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, more preferably at least one selected from the group consisting of a hydrogen atom and a methyl group, and even more preferably a hydrogen atom. Even more preferably, L 1 It is methyl and L 2 It is a hydrogen atom.

[0141] In equation (2), n is an integer from 1 to 4, preferably an integer of 1 or 2, and more preferably 1.

[0142] Among the imidazole compounds represented by the aforementioned general formula (2), it is preferably selected from at least one of the group consisting of the imidazole compounds represented by formula (2-1) and the imidazole compounds represented by formula (2-2), and more preferably the imidazole compounds represented by formula (2-1).

[0143] The imidazole compound represented by formula (2-1) below is 1-benzyl-2-methylimidazolium, and the imidazole compound represented by formula (2-2) below is 1-benzylimidazolium. That is, the imidazole compound represented by the aforementioned general formula (2) is preferably selected from at least one of the group consisting of 1-benzylimidazolium and 1-benzyl-2-methylimidazolium, and more preferably 1-benzyl-2-methylimidazolium.

[0144]

[0145] In the polyimide precursor composition of the present invention, the content of the imidazole compound shown in the aforementioned formula (2) is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of the aforementioned polyimide precursor, more preferably 1.0 to 50 parts by mass, further preferably 4.0 to 40 parts by mass, and even more preferably 10 to 30 parts by mass.

[0146] [Varnish]

[0147] The varnish of the present invention contains the aforementioned polyimide precursor composition and an organic solvent. That is, it contains the aforementioned polyimide precursor, the aforementioned imidazole compound, and an organic solvent, wherein the polyimide precursor and the imidazole compound are dissolved in the organic solvent.

[0148] The organic solvent can be used as long as it can dissolve the polyimide precursor and the imidazole compound, and there are no particular limitations. However, it is preferred to use the above-mentioned compounds, which are used as solvents in the manufacture of polyimide precursors, alone or in combination of two or more.

[0149] The varnish of the present invention can be formed by dissolving an imidazole compound in the above-mentioned polyimide precursor solution itself, or it can be formed by further mixing and diluting the polyimide precursor solution with a diluent and an imidazole compound, and then dissolving it.

[0150] The varnish of the present invention comprises the aforementioned imidazole compound, which acts as an imidization catalyst. Additionally, it may further contain a dehydration catalyst.

[0151] Examples of dehydration catalysts include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and other acid anhydrides; as well as carbodiimide compounds such as dicyclohexylcarbodiimide. They can be used alone or in combination of two or more.

[0152] The polyimide precursor contained in the varnish of the present invention is solvent-soluble, and therefore can be a stable, high-concentration varnish at room temperature. The varnish of the present invention preferably contains 3-40% by mass of the polyimide precursor (polyamic acid), more preferably 5-30% by mass. The viscosity of the varnish is preferably 0.1-100 Pa·s, more preferably 0.1-20 Pa·s. The viscosity of the varnish is the value measured using an E-type viscometer at 25°C.

[0153] In addition, without compromising the required properties of the polyimide film, the varnish of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoamers, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitizers.

[0154] The method for manufacturing the varnish of the present invention is not particularly limited, and known methods can be applied. For example, the aforementioned imidazole compound can be mixed and dissolved in a solution of the polyimide precursor obtained by the above manufacturing method, and the concentration can be adjusted by mixing solvents as needed, thereby obtaining the varnish.

[0155] [Polyimide film, and method for manufacturing polyimide film]

[0156] For the polyimide film of the present invention, it is preferred to manufacture it using the aforementioned varnish.

[0157] The polyimide film of the present invention is obtained by imidizing the aforementioned polyimide precursor, and therefore contains a polyimide resin having at least 70 mol% of repeating units of the following general formula (4) relative to all repeating units of the polyimide resin.

[0158] In the polyimide film of the present invention, the content of polyimide resin containing at least 70 mol% of the repeating units shown in the general formula (4) described below, relative to all repeating units of the polyimide resin, is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more. As an upper limit, it is preferably 99.9% by mass or less.

[0159] There are no particular limitations on the method for manufacturing polyimide films using the varnish of the present invention, and known methods can be used. For example, after coating the varnish of the present invention onto a smooth support such as a glass plate, metal plate, or plastic, or forming it into a film, the organic solvents such as reaction solvents and diluents contained in the varnish are removed by heating to obtain a polyamic acid film. The polyamic acid in the polyamic acid film is then imidized (dehydrated and closed-ring) by heating, and then peeled off from the support, thereby manufacturing a polyimide film.

[0160] That is, the polyimide film of the present invention is preferably a film obtained by coating the aforementioned varnish onto a support and heating it, and the manufacturing method of the polyimide film of the present invention is preferably a method of coating the aforementioned varnish onto a support and heating it.

[0161] The heating temperature for obtaining a polyimide precursor (polyamic acid) film by drying a varnish containing a polyimide precursor composition is preferably 50 to 150°C. The heating temperature for imidizing the polyimide precursor by heating is preferably 350 to 450°C, more preferably 380 to 420°C. Furthermore, the heating time is typically 1 minute to 6 hours, preferably 5 minutes to 2 hours, more preferably 15 minutes to 1 hour. By setting such a temperature / time, the physical properties of the obtained polyimide film become favorable.

[0162] Examples of heating atmospheres include air, nitrogen, oxygen, hydrogen, and nitrogen / hydrogen mixtures. However, to suppress the coloring of the resulting polyimide resin, nitrogen gas with an oxygen concentration of 100 ppm or less and nitrogen / hydrogen mixtures containing hydrogen concentration of 0.5% or less are preferred.

[0163] It should be noted that the imidization method is not limited to thermal imidization; chemical imidization can also be applied.

[0164] The thickness of the polyimide film of the present invention can be appropriately selected according to the application, but it is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more. Furthermore, it is preferably 250 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and even more preferably 20 μm or less. With a thickness within the above range, it can be practically used as a self-supporting membrane. By using the precursor composition of the present invention, it is also possible to produce a thin film of 20 μm or less, which is difficult to obtain, from the polyimide resin containing repeating units derived from tetracarboxylic acid having a norbornene backbone and p-phenylenediamine in a high ratio.

[0165] The thickness of the polyimide film can be easily controlled by adjusting the concentration and viscosity of the solid components in the varnish.

[0166] The polyimide film of the present invention has suitable physical properties as described below.

[0167] When the film is set to a thickness of 10 μm, the glass transition temperature (Tg) is preferably 400°C or higher, more preferably 420°C or higher, even more preferably 427°C or higher, and even more preferably 440°C or higher.

[0168] When the film is set to a thickness of 10 μm, the 1% weight reduction temperature (Td1%) is preferably 450°C or higher, more preferably 470°C or higher, even more preferably 480°C or higher, and even more preferably 490°C or higher.

[0169] When the film is set to a thickness of 10 μm, the tensile strength (according to JIS K7127) is preferably 90 MPa or more, more preferably 100 MPa or more, even more preferably 120 MPa or more, and even more preferably 140 MPa or more.

[0170] It should be noted that the above-mentioned physical property values ​​in this invention can be specifically determined by the method described in the embodiments.

[0171] The polyimide film of the present invention can be suitably used as a film for various components such as color filters, flexible displays, semiconductor components, and optical components. The polyimide film of the present invention is particularly suitable as a substrate for image display devices such as liquid crystal displays and OLED displays.

[0172] [Polyimide resin]

[0173] The polyimide resin of the present invention is a substance constituting the aforementioned polyimide film, and contains more than 70 mol% of the repeating units shown in general formula (4) relative to all repeating units of the polyimide resin.

[0174] That is, the aforementioned polyimide film contains the polyimide resin of the present invention, and the aforementioned polyimide film contains polyimide resin, which contains more than 70 mol% of the repeating units of general formula (4) relative to all repeating units of the polyimide resin.

[0175]

[0176] (in formula (4), X) 1 (It is a tetravalent group having at least one norbornene skeleton.)

[0177] It should be noted that the "repeating unit" in polyimide resin refers to an imide unit containing one structural unit derived from tetracarboxylic dianhydride and one structural unit derived from diamine.

[0178] In the aforementioned equation (4), X 1 It is a tetravalent group having at least one norbornene skeleton. X1 Preferably, it is obtained by removing two dicarboxylic anhydride moieties (four carboxyl moieties) from a tetracarboxylic dianhydride that is a raw material derived from the structural unit Al of the tetracarboxylic dianhydride described later.

[0179] In the aforementioned general formula (4), X 1 More preferably, it is selected from at least one of the group consisting of the tetravalent group shown in formula (3), the tetravalent group shown in formula (5), and the tetravalent group shown in formula (6), and even more preferably, it is the tetravalent group shown in formula (3).

[0180]

[0181] Through X 1 The polyimide film containing the polyimide resin has excellent heat resistance and strength, as shown in formula (3) with a tetravalent group.

[0182] (Composition of polyimide resin)

[0183] As described above, the polyimide resin contains repeating units represented by the aforementioned general formula (4). Specifically, from the viewpoints of improved heat resistance, increased strength, reduced yellowness, and improved transparency, the repeating units represented by the aforementioned formula (4) are 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more, relative to all the repeating units of the aforementioned polyimide resin. There is no upper limit, but it is 100 mol% or less.

[0184] Without impairing the effects of the present invention, the polyimide resin may contain repeating units other than those shown in the aforementioned general formula (4).

[0185] As a repeating unit other than the repeating unit shown in the aforementioned general formula (4), it is preferably selected from at least one of the repeating units shown in the following general formula (9) and the repeating units shown in the following general formula (10).

[0186]

[0187] (In equation (9), X) 1 Y is a tetravalent group having at least one norbornene skeleton. 2 It is a divalent aliphatic group, alicyclic group, aromatic group, or combination thereof with 4 to 39 carbon atoms. As a bonding group, it may have at least one selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-. Wherein, Y 2 It does not contain phenylene.

[0188] In equation (10), X2 It is a tetravalent aliphatic group, alicyclic group, aromatic group, or combination thereof with 4 to 39 carbon atoms. As a bonding group, it may have at least one selected from the group consisting of -O-, -SO2-, -CO-, -CH2-, -C(CH3)2-, -C2H4O-, and -S-. Wherein, X 2 It does not contain the norbornene skeleton.

[0189] The content of repeating units other than those shown in the aforementioned general formula (4) is 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, even more preferably 5 mol% or less, even more preferably 1 mol% or less, even more preferably 0 mol%, and even more preferably not included, relative to all repeating units of the aforementioned polyimide resin.

[0190] <Structural Units of Polyimide Resin>

[0191] The aforementioned polyimide resin contains repeating units as shown in the aforementioned general formula (4), and the structural units constituting the resin are the same as those described in the aforementioned <Structural Units of Polyimide Precursors> section.

[0192] That is, the polyimide resin has structural units Al derived from tetracarboxylic dianhydride and structural units B1 derived from diamine.

[0193] It should be noted that in the polyimide precursor, structural unit A1 and structural unit B1 form an amic acid structure.

[0194] The polyimide resin of the present invention comprises repeating units represented by the aforementioned general formula (4), wherein,

[0195] Structural unit A1 contains structural units (A11) derived from tetracarboxylic acid dianhydrides having at least one norbornene skeleton, and structural unit B1 contains structural units (B11) derived from compounds represented by the following formula (b1).

[0196]

[0197] (Structural unit A1)

[0198] Structural unit Al is a structural unit derived from tetracarboxylic dianhydride, including structural units (Al1) derived from tetracarboxylic dianhydride having at least one norbornene skeleton.

[0199] By incorporating structural units derived from tetracarboxylic acid dianhydrides with a norbornene backbone, polyimide films with excellent heat resistance and strength can be obtained.

[0200] The ratio of structural units (Al1) in structural unit Al is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more. There is no particular upper limit to this ratio, but it is 100 mol% or less.

[0201] Examples of tetracarboxylic dianhydrides derived from a tetracarboxylic dianhydride having at least one norbornene skeleton include compounds shown in formula (a1), compounds shown in formula (a2), and compounds shown in formula (a3).

[0202]

[0203] The compound represented by formula (a1) is norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic acid dianhydride (CpODA). The compound represented by formula (a2) is 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride (BNBDA). The compound represented by formula (a3) ​​is decahydro-1H,3H-4,10:5,9-dimethylbridgednaphthalene[2,3-c:6,7-c']difuran-1,3,6,8-tetraone (DNDA).

[0204] Among them, the compound represented by the preferred formula (a1) preferably contains structural unit A1 derived from the compound represented by formula (a1).

[0205] By setting the structural unit (Al1) derived from the compound shown in formula (a1) as the structural unit of the polyimide resin, the polyimide film made of the polyimide resin exhibits excellent heat resistance and strength.

[0206] Structural unit Al can include structural units other than those derived from tetracarboxylic dianhydrides having a norbornene skeleton. There are no particular limitations on such structural units, and examples include structural units derived from aromatic tetracarboxylic dianhydrides, structural units derived from alicyclic tetracarboxylic dianhydrides other than structural unit (Al1), and structural units derived from aliphatic tetracarboxylic dianhydrides.

[0207] Examples of aromatic tetracarboxylic dianhydrides that impart structural units derived from aromatic tetracarboxylic dianhydrides include biphenyl tetracarboxylic dianhydride (BPDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), pyromellitic dianhydride, 3,3',4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 2,2',3,3'-benzophenone tetracarboxylic dianhydride.

[0208] Examples of alicyclic tetracarboxylic dianhydrides that serve as structural units derived from alicyclic tetracarboxylic dianhydrides other than the structural unit (Al1) include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and dicyclohexyltetracarboxylic dianhydride.

[0209] Examples of aliphatic tetracarboxylic dianhydrides that provide structural units derived from aliphatic tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydrides.

[0210] The structural unit A1 may optionally contain one type of structural unit or two or more types of structural units.

[0211] It should be noted that, in this specification, aromatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing one or more alicyclic rings but not aromatic rings, and aliphatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride not containing either aromatic or alicyclic rings.

[0212] (Structural unit B1)

[0213] The structural unit Bl is a structural unit derived from diamine, and contains structural units (Bl1) derived from compounds represented by the following formula (b1).

[0214]

[0215] By including structural unit (Bl1) in structural unit Bl, polyimide films made of polyimide resin exhibit excellent heat resistance and strength.

[0216] The ratio of structural units (Bl1) in structural unit B1 is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 99 mol% or more. There is no particular upper limit to this ratio, but it is 100 mol% or less.

[0217] Structural unit Bl can include structural units other than structural unit (Bl1). There are no particular limitations on such structural units, and examples include structural units derived from aromatic diamines, structural units derived from alicyclic diamines, and structural units derived from aliphatic diamines other than structural unit (Bl1).

[0218] Examples of aromatic diamines that provide structural units other than the structural unit (Bl1) derived from aromatic diamines include 2,2'-bis(trifluoromethyl)benzidine (TFMB), 3,5-diaminobenzoic acid (3,5-DABA), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4-aminophenyl 4-aminobenzoate (4-BAAB), p-phenylenediamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-dimethylbiphenyl-4,4'-diamine, and 4,4'-diphenylamine. Aminodiphenylmethane, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobenzoylaniline, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and 1,4-bis(4-aminophenoxy)benzene, etc.

[0219] Examples of alicyclic diamines that impart structural units derived from alicyclic diamines include 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane.

[0220] Examples of aliphatic diamines that provide structural units derived from aliphatic diamines include ethylenediamine and hexamethylenediamine.

[0221] It should be noted that, in this specification, aromatic diamines refer to diamines containing one or more aromatic rings, alicyclic diamines refer to diamines containing one or more alicyclic rings but not aromatic rings, and aliphatic diamines refer to diamines that do not contain either aromatic or alicyclic rings.

[0222] The structural unit Bl can optionally contain one type of structural unit or two or more types of structural units.

[0223] Without prejudice to the invention, the polyimide resin of the present invention may contain structures other than polyimide chains (structures formed by structural units A1 and B1 bonded together by imide). Examples of structures other than polyimide chains that may be included in the polyimide resin include structures containing amide bonds.

[0224] The polyimide resin of the present invention preferably comprises a polyimide chain (a structure formed by structural unit A1 and structural unit B1 bonded together by imide) as the main structure. Therefore, the proportion of the polyimide chain in the polyimide resin of the present invention is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 99% by mass or more, and even more preferably 100% by mass.

[0225] The tensile strength (according to JIS K7127) of the polyimide resin of the present invention when the film is set as a thickness of 10 μm is preferably 90 MPa or more, more preferably 100 MPa or more, further preferably 120 MPa or more, and even more preferably 140 MPa or more. Specifically, the tensile strength can be measured by the method described in the examples.

[0226] Example

[0227] The present invention will now be specifically described through examples. However, the present invention is not limited to these examples.

[0228] <Membrane Properties and Evaluation>

[0229] The physical properties of the membranes obtained in the examples and comparative examples were determined by the methods shown below.

[0230] (1) Film thickness

[0231] For the film thickness, a micrometer manufactured by Mitutoyo was used for measurement.

[0232] (2) Total transmittance and yellow index (YI)

[0233] For total transmittance and turbidity (YI), measurements were taken according to JIS K7136 and ASTM E313-05 (D light source, 65°) using a color / turbidity simultaneous measuring instrument "COH7700" manufactured by NIPPONDENSHOKU INDUSTRIES Co., Ltd.

[0234] (3) Glass transition temperature (Tg) (Evaluation of heat resistance)

[0235] Using a HITACHI HIGH-TECH SCIENCE CORPORATION thermomechanical analyzer "TMA / 7100C", the elongation of the test specimen was measured in tensile mode under the conditions of a sample size of 3 mm × 20 mm, a load of 50 mN, a nitrogen gas flow (flow rate of 200 mL / min), and a heating rate of 10 °C / min, from 40 °C to 500 °C. The glass transition temperature was determined by extrapolation from the inflection point of elongation.

[0236] (4) 1% weight reduction temperature (Td1%) (Evaluation of heat resistance)

[0237] A differential thermal and thermogravimetric analysis (DTACHI HIGH-TECH SCIENCE CORPORATION NEXTASTA200RV apparatus was used for simultaneous differential thermal and thermogravimetric analysis. The sample was heated from 40°C to 150°C at a rate of 10°C / min, held at 150°C for 30 minutes to remove moisture, and then heated to 510°C. The weight was compared with that after holding at 150°C for 30 minutes, and the temperature at which a 1% weight reduction occurred was defined as the 1% weight reduction temperature. A higher weight reduction temperature indicates better heat resistance.

[0238] (5) Coefficient of linear thermal expansion (CTE)

[0239] Using a HITACHI HIGH-TECH SCIENCE CORPORATION thermomechanical analyzer "TMA / 7100C", TMA was measured in tensile mode under the conditions of a sample size of 3 mm × 20 mm, a load of 50 mN, and a heating rate of 10 °C / min. The CTE from 100 to 400 °C was determined.

[0240] (6) Elastic modulus and strength

[0241] The elastic modulus and strength were measured using a tensile testing machine "Strograft VG-1E" manufactured by Toyo Seiki Co., Ltd., based on the tensile elastic modulus and tensile strength of JIS K7127.

[0242] The tetracarboxylic acid and diamine components used in the examples and comparative examples, and their abbreviations, are described below.

[0243] <Tetracarboxylic acid component>

[0244] CpODA: norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic dianhydride (the compound shown in formula (a1); manufactured by ENEOS Corporation)

[0245] BNBDA: 5,5'-bis-2-norbornen-5,5',6,6'-tetracarboxylic acid-5,5',6,6'-dianhydride (the compound shown in formula (a2); manufactured by ENEOS Corporation)

[0246] DNDA: decahydro-1H,3H-4,10:5,9-dimethylbridged naphthalene[2,3-c:6,7-c']difuran-1,3,6,8-tetraone (the compound shown in formula (a3); manufactured by Daxin Materials Corporation)

[0247] <Diamine component>

[0248] PPD: p-Phenylenediamine (the compound shown in formula (b1); manufactured by Tokyo Chemical Industry Co., Ltd.)

[0249] The abbreviations of the solvents used in the examples and comparative examples are as follows.

[0250] NMP: N-methyl-2-pyrrolidone (manufactured by Tokyo Pure Pharmaceutical Co., Ltd.)

[0251] Example 1

[0252] A solution was obtained by adding 21.956 g (0.203 mol) of PPD and 53.333 g of NMP4 to a 1 L five-necked round-bottom flask equipped with a stainless steel crescent-shaped stirring blade, a nitrogen inlet pipe, a Dean-Stark water separator with cooling pipes, a thermometer, and glass end caps. The mixture was stirred at 200 rpm under a nitrogen atmosphere at a system temperature of 10 °C.

[0253] 78.044 g (0.203 mol) of CpODA and 113.333 g of NMP were added to the solution and stirred at 10 °C for 5 hours to obtain a polyimide precursor solution 1 with a solid component concentration of 10% by mass.

[0254] Next, 0.5 g of 1-benzyl-2-methylimidazolium (5 parts by mass relative to 100 parts by mass of the polyimide precursor (total amount of tetracarboxylic acid and diamine components)) was added to the obtained polyimide precursor solution 1,100 g to obtain a polyimide precursor composition varnish.

[0255] Next, the polyimide precursor composition varnish obtained by spin coating was applied to a glass plate and held at 80°C for 20 minutes on a heated plate. Then, it was heated at 420°C for 60 minutes (heating rate 5°C / min) in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby thermally imidizing the varnish to obtain a polyimide film. The results of the film evaluation are shown in Table 1.

[0256] Examples 2-4

[0257] In the same polyimide precursor solution 1 100g obtained in Example 1, the imidazole compounds (1-benzyl-2-methylimidazolium, 1-benzylimidazolium) shown in Table 1 were added in the amounts shown in Table 1 (5 parts by mass or 15 parts by mass relative to 100 parts by mass of polyimide precursor (total amount of tetracarboxylic acid component and diamine component)) to obtain polyimide precursor composition varnish.

[0258] Next, a polyimide film was obtained using the same method as in Example 1. The results of the film evaluation are shown in Table 1.

[0259] Comparative Example 1

[0260] Using the same polyimide precursor solution 1 obtained in the same manner as in Example 1, a polyimide film was obtained by the same method as in Example 1. The resulting film was fragile and difficult to maintain its shape if peeled off from the glass; therefore, the film evaluation shown in Table 1 could not be performed.

[0261] Comparative Examples 2-4

[0262] In the same polyimide precursor solution 1 100g obtained in Example 1, 0.5g of imidazole compounds (imidazole, 1,2-dimethylimidazole, benzimidazole) as shown in Table 1 were added (5 parts by mass relative to 100 parts by mass of polyimide precursor (total amount of tetracarboxylic acid component and diamine component)) to obtain polyimide precursor composition varnish.

[0263] Next, a polyimide film was obtained using the same method as in Example 1. The films obtained in Comparative Examples 2 and 3 were fragile and could not maintain their shape if peeled off from the glass; therefore, the film evaluations shown in Table 1 could not be performed. The results of the film evaluation for the film obtained in Comparative Example 4 are shown in Table 1.

[0264] Example 5

[0265] In a 1L 5-necked round-bottom flask equipped with a stainless steel crescent-shaped stirring blade, a nitrogen inlet pipe, a water separator with a cooling pipe, a thermometer, and a glass end cap, 23.231g (0.215 mol) of PPD and 453.333g of NMP were added. The mixture was stirred at 10°C under a nitrogen atmosphere and at 200 rpm to obtain a solution.

[0266] Add 41.287 g (0.107 mol) of CpODA, 35.482 g (0.107 mol) of BNBDA and 113.333 g of NMP to the solution, and stir at 10 °C for 5 hours to obtain a polyimide precursor solution 2 with a solid component concentration of 10% by mass.

[0267] Next, 0.5 g of 1-benzyl-2-methylimidazolium (5 parts by mass relative to 100 parts by mass of the polyimide precursor (total amount of tetracarboxylic acid and diamine components)) was added to the obtained polyimide precursor solution 2 100 g to obtain a polyimide precursor composition varnish.

[0268] Next, the polyimide precursor composition varnish obtained by spin coating was applied to a glass plate and held at 80°C for 20 minutes on a heated plate. Then, it was heated at 420°C for 60 minutes (heating rate 5°C / min) in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby thermally imidizing the varnish to obtain a polyimide film. The results of the film evaluation are shown in Table 1.

[0269] Example 6

[0270] In a 1L five-necked round-bottom flask equipped with a stainless steel crescent-shaped stirring blade, a nitrogen inlet pipe, a water separator with a cooling pipe, a thermometer, and a glass end cap, 23.953g (0.221 mol) of PPD and 453.333g of NMP were added. The mixture was stirred at 10°C under a nitrogen atmosphere and at 200 rpm to obtain a solution.

[0271] Add 42.570 g (0.111 mol) of CpODA, 33.477 g (0.111 mol) of DNDA, and 13.333 g of NMP to the solution and stir at 10 °C for 5 hours to obtain a polyimide precursor solution 3 with a solid component concentration of 10% by mass.

[0272] Next, 1.5 g of 1-benzyl-2-methylimidazolium (15 parts by mass relative to 100 parts by mass of the polyimide precursor (total amount of tetracarboxylic acid and diamine components)) was added to the obtained polyimide precursor solution 3 100 g to obtain a polyimide precursor composition varnish.

[0273] Next, the polyimide precursor composition varnish obtained by spin coating was applied to a glass plate and held at 80°C for 20 minutes on a heated plate. Then, it was heated at 420°C for 60 minutes (heating rate 5°C / min) in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, thereby thermally imidizing the varnish to obtain a polyimide film. The results of the film evaluation are shown in Table 1.

[0274] [Table 1]

[0275] Table 1

[0276]

[0277] (*1) The numbers in the precursor column indicate the molar ratio of each component.

[0278] (*2) The numbers in the imidazole compound column indicate the amount of imidazole compound added relative to the precursor (phr: parts by mass relative to 100 parts by mass of the precursor).

[0279] As shown in Table 1, the polyimide films obtained using the polyimide precursor compositions of the examples exhibit high glass transition temperatures, high 1% weight loss temperatures, and high tensile strength, indicating excellent heat resistance and strength. On the other hand, Comparative Example 1, which did not use an imidazole-based compound, and Comparative Examples 2 and 3, which used imidazole or 1,2-dimethylimidazole as imidazole-based compounds, only yielded fragile films. Furthermore, while Comparative Example 4, which used benzimidazole as an imidazole-based compound, produced a film, its strength was poor.

Claims

1. A polyimide precursor composition comprising: a polyimide precursor containing at least 70 mol% of repeating units of the following general formula (1) relative to all repeating units, and an imidazole compound of the following general formula (2). The content of the imidazole compound represented by general formula (2) is 1.0 to 50 parts by weight relative to 100 parts by weight of the polyimide precursor. In equation (1), X 1 R is selected from at least one of the group consisting of the tetravalent group shown in formula (3), the tetravalent group shown in formula (5), and the tetravalent group shown in formula (6). 1 and R 2 Each is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, in formula (2), L 1 and L 2 Each group consists independently of a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a carboxyl group, and a hydroxyl group, where n is an integer from 1 to 4. 。 2. The polyimide precursor composition according to claim 1, wherein, In the general formula (1), X 1 The tetravalent group is shown in formula (3). 。 3. The polyimide precursor composition according to claim 1 or 2, wherein, The imidazole compound represented by general formula (2) is selected from at least one of the groups consisting of 1-benzylimidazole and 1-benzyl-2-methylimidazole.

4. The polyimide precursor composition according to claim 1 or 2, wherein, relative to all repeating units of the polyimide precursor, it comprises more than 90 mol% of the repeating units represented by the general formula (1).

5. A varnish comprising the polyimide precursor composition according to any one of claims 1 to 4 and an organic solvent.

6. A polyimide film obtained by applying the varnish of claim 5 onto a support and heating it.

7. A method for manufacturing a polyimide film, wherein the varnish of claim 5 is applied to a support and heated.

8. The polyimide film according to claim 6, wherein the polyimide film comprises a polyimide resin, the polyimide resin comprising at least 70 mol% of repeating units of general formula (4) relative to all repeating units of the polyimide resin. In equation (4), X 1 It is selected from at least one of the group consisting of the tetravalent group shown in formula (3), the tetravalent group shown in formula (5), and the tetravalent group shown in formula (6). 。 9. The polyimide film according to claim 8, wherein, In the general formula (4), X 1 The tetravalent group is shown in formula (3). 。 10. The polyimide film according to claim 6 or 8, wherein, The thickness of the polyimide film is less than 20 μm.

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