WO2019151336A1 - Polyimide resin composition and polyimide film - Google Patents

Abstract

The present invention provides a polyimide resin composition that has excellent storage stability and makes it possible to form a film that has excellent mechanical characteristics, organic solvent resistance, colorless transparency, and optical isotropy. The present invention also provides a polyimide film. A polyimide resin composition that includes a polyimide resin and a crosslinking agent that has at least two oxazolyl groups. The polyimide resin has a structural unit A and a structural unit B that is derived from a diamine. Structural unit A includes at least one structural unit (A-1) selected from the group that consists of structural units (A-1-1) derived from compounds represented by formula (a-1-1) and structural units (A-1-2) derived from compounds represented by formula (a-1-2). Structural unit B includes a structural unit (B-1) derived from a compound represented by formula (b-1) and a structural unit (B-2) derived from a compound represented by formula (b-2). A polyimide film that is formed as a result of the polyimide resin in the polyimide resin composition being crosslinked by the crosslinking agent. (In formula (b-1), each R is independently a hydrogen atom, a fluorine atom, or a methyl group. In formula (b-2), X is a single bond or a specific group, p is an integer from 0 to 2, m1 is an integer from 0 to 4, and m2 is an integer from 0 to 4, provided that when p is 0, m1 is an integer from 1 to 4.)

Description

Polyimide resin composition and polyimide film

The present invention relates to a polyimide resin composition and a polyimide film.

Since polyimide resin has excellent mechanical properties and heat resistance, various uses are being studied in the fields of electric and electronic parts. For example, it is desired to replace a glass substrate used for an image display device such as a liquid crystal display or an OLED display with a plastic substrate for the purpose of reducing the weight or flexibility of the device. Research is ongoing. The polyimide film for such use is required to be colorless and transparent.

In addition, a film having poor resistance to organic solvents such as polar solvents (organic solvent resistance) may change its form due to elution or swelling of the surface when exposed to an organic solvent such as polar solvents. Polyimide films often require organic solvent resistance. In order to meet such a demand, a polyimide film manufactured by adding a crosslinking agent to a polyimide resin has been proposed.
Patent Document 1 discloses a polyimide resin composition containing a polyimide resin having a carboxyl group and a crosslinking agent having at least two oxazolyl groups, and the polyimide resin composition provides a film having good transparency and high hardness. Is described as being possible.
Patent Document 2 discloses a transparent flexible film containing a polyimide copolymer having a carboxyl group and a polyfunctional epoxide.

Japanese Patent Application Laid-Open No. 2016-222797 Japanese Patent No. 6174580

In an image display device, when light emitted from a display element is emitted through a plastic substrate, the plastic substrate is required to be colorless and transparent, and when light passes through a retardation film or a polarizing plate ( For example, liquid crystal displays, touch panels, etc.) are required to have high optical isotropy in addition to colorless transparency. However, Patent Document 1 does not describe any optical isotropy.
In Patent Document 2, the reaction of the epoxy group of the polyfunctional epoxide added as a crosslinking agent with the carboxy group proceeds even at a relatively low temperature (about 30 ° C. or higher). For this reason, a composition containing a polyimide resin having a carboxyl group and a polyfunctional epoxide undergoes gelation due to crosslinking when stored at room temperature, and storage stability is poor. In general, the thermal decomposition temperature of an epoxy resin is 250 to 350 ° C., and it is considered that the heat resistance is insufficient for applications requiring a high temperature process.
The present invention has been made in view of the above situation, and the object of the present invention is to form a film having excellent mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy. An object of the present invention is to provide a polyimide resin composition having excellent storage stability and to provide a polyimide film obtained by crosslinking a polyimide resin in the polyimide resin composition with a crosslinking agent.

The present inventors have found that a polyimide resin composition containing a polyimide resin containing a specific combination of structural units and a specific cross-linking agent can solve the above problems, and has completed the invention.

（式（ｂ－１）中、Ｒはそれぞれ独立して、水素原子、フッ素原子、又はメチル基であり；式（ｂ－２）中、Ｘは単結合、置換若しくは無置換のアルキレン基、カルボニル基、エーテル基、下記式（ｂ－２－ｉ）で表される基、又は下記式（ｂ－２－ｉｉ）で表される基であり、ｐは０～２の整数であり、ｍ１は０～４の整数であり、ｍ２は０～４の整数である。ただし、ｐが０の場合、ｍ１は１～４の整数である。）

（式（ｂ－２－ｉ）中、ｍ３は０～５の整数であり；式（ｂ－２－ｉｉ）中、ｍ４は０～５の整数である。なお、ｍ１＋ｍ２＋ｍ３＋ｍ４は１以上であり、ｐが２の場合、２つのＸ及び２つのｍ２～ｍ４のそれぞれは独立して選択される。） That is, the present invention relates to the following [1] to [9].
[1]
A polyimide resin composition comprising a polyimide resin and a crosslinking agent having at least two oxazolyl groups,
The polyimide resin has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,
The structural unit A is derived from a structural unit (A-1-1) derived from a compound represented by the following formula (a-1-1) and a compound represented by the following formula (a-1-2). Comprising at least one structural unit (A-1) selected from the group consisting of units (A-1-2),
The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1) and a structural unit (B-2 derived from a compound represented by the following formula (b-2). And a polyimide resin composition.

(In the formula (b-1), each R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group, a carbonyl A group, an ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, and m1 is (It is an integer from 0 to 4, and m2 is an integer from 0 to 4. However, when p is 0, m1 is an integer from 1 to 4.)

(In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5. Note that m1 + m2 + m3 + m4 is 1 or more. When p is 2, each of the two X and the two m2 to m4 is independently selected.)

［３］
　前記架橋剤が、前記少なくとも２つのオキサゾリル基が結合したベンゼン環を含む、上記［１］又は［２］に記載のポリイミド樹脂組成物。
［４］
　前記架橋剤中のオキサゾリル基と前記ポリイミド樹脂中のカルボキシル基とのモル比（オキサゾリル基／カルボキシル基）が１／４～１／０．５の範囲となるような比率で、前記ポリイミド樹脂と前記架橋剤とを含む、上記［１］～［３］のいずれかに記載のポリイミド樹脂組成物。
［５］
　構成単位Ｂ中における構成単位（Ｂ－１）の比率が４０～９９モル％であり、
　構成単位Ｂ中における構成単位（Ｂ－２）の比率が１～６０モル％である、上記［１］～［４］のいずれかに記載のポリイミド樹脂組成物。
［６］
　構成単位Ａ中における構成単位（Ａ－１）の比率が５０モル％以上である、上記［１］～［５］のいずれかに記載のポリイミド樹脂組成物。
［７］
　構成単位（Ａ－１）が構成単位（Ａ－１－１）である、上記［１］～［６］のいずれかに記載のポリイミド樹脂組成物。
［８］
　構成単位（Ａ－１）が構成単位（Ａ－１－２）である、上記［１］～［６］のいずれかに記載のポリイミド樹脂組成物。
［９］
　上記［１］～［８］のいずれかに記載のポリイミド樹脂組成物中の前記ポリイミド樹脂が前記架橋剤により架橋されてなるポリイミドフィルム。 [2]
The polyimide resin composition according to the above [1], wherein the structural unit (B-2) is a structural unit (B-21) derived from a compound represented by the following formula (b-21).

[3]
The polyimide resin composition according to the above [1] or [2], wherein the crosslinking agent comprises a benzene ring to which the at least two oxazolyl groups are bonded.
[4]
In a ratio such that the molar ratio of the oxazolyl group in the crosslinking agent to the carboxyl group in the polyimide resin (oxazolyl group / carboxyl group) is in the range of 1/4 to 1 / 0.5, the polyimide resin and the The polyimide resin composition according to any one of the above [1] to [3], comprising a crosslinking agent.
[5]
The ratio of the structural unit (B-1) in the structural unit B is 40 to 99 mol%,
The polyimide resin composition according to any one of [1] to [4] above, wherein the proportion of the structural unit (B-2) in the structural unit B is 1 to 60 mol%.
[6]
The polyimide resin composition according to any one of [1] to [5] above, wherein the proportion of the structural unit (A-1) in the structural unit A is 50 mol% or more.
[7]
The polyimide resin composition according to any one of [1] to [6] above, wherein the structural unit (A-1) is the structural unit (A-1-1).
[8]
The polyimide resin composition according to any one of [1] to [6] above, wherein the structural unit (A-1) is the structural unit (A-1-2).
[9]
A polyimide film obtained by crosslinking the polyimide resin in the polyimide resin composition according to any one of the above [1] to [8] with the crosslinking agent.

The polyimide resin composition of the present invention is excellent in storage stability and can form a film excellent in mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy.

[Polyimide resin composition]
The polyimide resin composition of the present invention contains a polyimide resin and a crosslinking agent. Hereinafter, the polyimide resin and the crosslinking agent in the present invention will be described.

（式（ｂ－１）中、Ｒはそれぞれ独立して、水素原子、フッ素原子又はメチル基であり；式（ｂ－２）中、Ｘは単結合、置換若しくは無置換のアルキレン基、カルボニル基、エーテル基、下記式（ｂ－２－ｉ）で表される基、又は下記式（ｂ－２－ｉｉ）で表される基であり、ｐは０～２の整数であり、ｍ１は０～４の整数であり、ｍ２は０～４の整数である。ただし、ｐが０の場合、ｍ１は１～４の整数である。）

（式（ｂ－２－ｉ）中、ｍ３は０～５の整数であり；式（ｂ－２－ｉｉ）中、ｍ４は０～５の整数である。なお、ｍ１＋ｍ２＋ｍ３＋ｍ４は１以上であり、ｐが２の場合、２つのＸ及び２つのｍ２～ｍ４のそれぞれは独立して選択される。） <Polyimide resin>
In the present invention, the polyimide resin has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine, and the structural unit A is a compound represented by the following formula (a-1-1). A structure which is at least one selected from the group consisting of a structural unit (A-1-1) derived from and a structural unit (A-1-2) derived from a compound represented by the following formula (a-1-2) A structural unit (B-1) containing the unit (A-1), wherein the structural unit B is derived from a compound represented by the following formula (b-1), and a compound represented by the following formula (b-2): Derived structural unit (B-2).

(In the formula (b-1), each R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group or a carbonyl group. , An ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, and m1 is 0. And m2 is an integer from 0 to 4. However, when p is 0, m1 is an integer from 1 to 4.)

(In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5. Note that m1 + m2 + m3 + m4 is 1 or more. When p is 2, each of the two X and the two m2 to m4 is independently selected.)

(Structural unit A)
The structural unit A is a structural unit derived from tetracarboxylic dianhydride in the polyimide resin, and is derived from a compound represented by the following formula (a-1-1) (A-1-1) And a structural unit (A-1) that is at least one selected from the group consisting of a structural unit (A-1-2) derived from a compound represented by the following formula (a-1-2).

The compound represented by the formula (a-1-1) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.
The compound represented by the formula (a-1-2) is norbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″- Tetracarboxylic dianhydride.
When the structural unit A contains the structural unit (A-1), it contributes to the improvement of colorless transparency of the film. Further, when the structural unit (A-1-1) is included as the structural unit (A-1), it can also contribute to the improvement of the optical isotropy of the film.

The structural unit (A-1) may be only the structural unit (A-1-1) or only the structural unit (A-1-2). The structural unit (A-1) may be a combination of the structural unit (A-1-1) and the structural unit (A-1-2).

The ratio of the structural unit (A-1) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol%. % Or more. The upper limit value of the ratio of the structural unit (A-1) is not particularly limited, that is, 100 mol%. The structural unit A may consist of only the structural unit (A-1).

The structural unit A may include a structural unit other than the structural unit (A-1). The tetracarboxylic dianhydride that gives such a structural unit is not particularly limited, but pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3, 3 ', 4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 9,9'-bis (3,4-dicarboxyphenyl) fluorene dianhydride 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) ) Propane dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 3,4′-oxydiphthalic anhydride, 3,3′- Oxydiphthalic anhydride 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 4,4- (p-phenylenedioxy) diphthalic acid Dianhydrides and aromatic tetracarboxylic dianhydrides such as 4,4- (m-phenylenedioxy) diphthalic acid non-hydrate; 1,2,3,4-cyclobutanetetracarboxylic dianhydride and the like An alicyclic tetracarboxylic dianhydride (except the compound represented by the formula (a-1-1) and the compound represented by the formula (a-1-2)); and 1,2,3, And aliphatic tetracarboxylic dianhydrides such as 4-butanetetracarboxylic dianhydride.
In this specification, an aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and an alicyclic tetracarboxylic dianhydride means one alicyclic ring. The tetracarboxylic dianhydride containing the above and containing no aromatic ring means an aliphatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.
The number of structural units other than the structural unit (A-1) optionally contained in the structural unit A may be one or more.

A preferred embodiment of the structural unit other than the structural unit (A-1) includes a structural unit (A-2) derived from a compound represented by the following formula (a-2).

The compound represented by the formula (a-2) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3 ′, 4, represented by the following formula (a-2s): 4′-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2a), Examples thereof include 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride (i-BPDA) represented by the following formula (a-2i).

When the structural unit A includes the structural unit (A-1) and the structural unit (A-2), the ratio of the structural unit (A-1) in the structural unit A is preferably 50 to 95 mol%, and more It is preferably 70 to 95 mol%, more preferably 85 to 95 mol%, and the ratio of the structural unit (A-2) in the structural unit A is preferably 5 to 50 mol%, more preferably It is 5 to 30 mol%, and more preferably 5 to 15 mol%.
The structural unit A may consist of only the structural unit (A-1) and the structural unit (A-2).

（式（ｂ－１）中、Ｒはそれぞれ独立して、水素原子、フッ素原子、又はメチル基であり；式（ｂ－２）中、Ｘは単結合、置換若しくは無置換のアルキレン基、カルボニル基、エーテル基、下記式（ｂ－２－ｉ）で表される基、又は下記式（ｂ－２－ｉｉ）で表される基であり、ｐは０～２の整数であり、ｍ１は０～４の整数であり、ｍ２は０～４の整数である。ただし、ｐが０の場合、ｍ１は１～４の整数である。）

（式（ｂ－２－ｉ）中、ｍ３は０～５の整数であり；式（ｂ－２－ｉｉ）中、ｍ４は０～５の整数である。なお、ｍ１＋ｍ２＋ｍ３＋ｍ４は１以上であり、ｐが２の場合、２つのＸ及び２つのｍ２～ｍ４のそれぞれは独立して選択される。） (Structural unit B)
The structural unit B is a structural unit derived from a diamine in the polyimide resin, the structural unit (B-1) derived from a compound represented by the following formula (b-1), and the following formula (b-2) And a structural unit (B-2) derived from a compound represented by the formula:

(In the formula (b-1), each R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group, a carbonyl A group, an ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, and m1 is (It is an integer from 0 to 4, and m2 is an integer from 0 to 4. However, when p is 0, m1 is an integer from 1 to 4.)

(In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5. Note that m1 + m2 + m3 + m4 is 1 or more. When p is 2, each of the two X and the two m2 to m4 is independently selected.)

In the formula (b-1), each R is independently a hydrogen atom, a fluorine atom or a methyl group, preferably a hydrogen atom. Examples of the compound represented by the formula (b-1) include 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (3-fluoro-4-aminophenyl) fluorene, and 9,9-bis. Examples include (3-methyl-4-aminophenyl) fluorene, and 9,9-bis (4-aminophenyl) fluorene is preferred.
When the structural unit B includes the structural unit (B-1), the optical isotropy of the film is improved.

Specific examples of the compound represented by the formula (b-2) include compounds represented by the following formulas (b-21) to (b-27).

Among the above compounds, a compound represented by the formula (b-21) is preferable, and a compound represented by the following formula (b-211), that is, 3,5-diaminobenzoic acid is more preferable.

The structural unit (B-2) is a structural unit that gives a carboxyl group to the polyimide resin. When the polyimide resin has a carboxyl group, the polyimide resins can be cross-linked via a cross-linking agent described later. Therefore, when the structural unit B includes the structural unit (B-2), the organic solvent resistance of the film is improved.

The ratio of the structural unit (B-1) in the structural unit B is preferably 40 to 99 mol%, more preferably 45 to 95 mol%, still more preferably 75 to 95 mol%, and particularly preferably. Is 80 to 90 mol%.
The ratio of the structural unit (B-2) in the structural unit B is preferably 1 to 60 mol%, more preferably 5 to 55 mol%, still more preferably 5 to 25 mol%, and particularly preferably. Is 10 to 20 mol%.
The total ratio of the structural unit (B-1) and the structural unit (B-2) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol%. % Or more, particularly preferably 99 mol% or more. The upper limit of the total ratio of the structural unit (B-1) and the structural unit (B-2) is not particularly limited, that is, 100 mol%. The structural unit B may consist of only the structural unit (B-1) and the structural unit (B-2).

The structural unit B may include structural units other than the structural units (B-1) and (B-2). The diamine giving such a structural unit is not particularly limited, but 1,4-phenylenediamine, p-xylylenediamine, 2,2′-dimethylbiphenyl-4,4′-diamine, and 2,2′-bis. (Trifluoromethyl) benzidine, 4,4′-diaminodiphenyl ether, 4,4′-diamino-2,2′-bistrifluoromethyl diphenyl ether, 4,4′-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) ) Hexafluoropropane, bis (4-aminophenyl) sulfone, 4,4'-diaminobenzanilide, 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, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis (4- (4-aminophenoxy) ) Phenyl) hexafluoropropane, 5,5 ′-(1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl) -2,2′-dimethylbiphenyl-4,4′-diamine and 9 , 9-bis (4- (4-aminophenoxy) phenyl) fluorene and other aromatic diamines (except for the compound represented by formula (b-1) and the compound represented by formula (b-2)) Alicyclic diamines such as 1,3-bis (aminomethyl) cyclohexane and 1,4-bis (aminomethyl) cyclohexane; and aliphatics such as ethylenediamine and hexamethylenediamine Amines.
In this specification, an aromatic diamine means a diamine containing one or more aromatic rings, an alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, A group diamine means a diamine containing neither an aromatic ring nor an alicyclic ring.
The structural units other than the structural units (B-1) and (B-2) optionally included in the structural unit B may be one type or two or more types.

In the present invention, the number average molecular weight of the polyimide resin is preferably 5,000 to 100,000 from the viewpoint of the mechanical strength of the resulting polyimide film. In addition, the number average molecular weight of a polyimide resin can be calculated | required from the standard polymethylmethacrylate (PMMA) conversion value by gel filtration chromatography measurement, for example.

<Production method of polyimide resin>
In the present invention, the polyimide resin comprises a tetracarboxylic acid component containing a compound that provides the structural unit (A-1), a compound that provides the structural unit (B-1), and the structural unit (B-2). ) Can be produced by reacting with a diamine component containing a compound that gives.

As the compound giving the structural unit (A-1), at least one selected from the group consisting of a compound giving the structural unit (A-1-1) and a compound giving the structural unit (A-1-2) is used.
Examples of the compound that provides the structural unit (A-1-1) include compounds represented by the formula (a-1-1), but are not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. Good. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1-1) (that is, 1,2,4,5-cyclohexanetetracarboxylic acid), and the tetracarboxylic acid Examples include alkyl esters of acids. As the compound giving the structural unit (A-1-1), a compound represented by the formula (a-1-1) (that is, dianhydride) is preferable.
Examples of the compound that provides the structural unit (A-1-2) include compounds represented by the formula (a-1-2), but are not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. Good. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1-2), and an alkyl ester of the tetracarboxylic acid. As the compound giving the structural unit (A-1-2), a compound represented by the formula (a-1-2) (that is, dianhydride) is preferable.

As the compound that provides the structural unit (A-1), only a compound that provides the structural unit (A-1-1) may be used, or only a compound that provides the structural unit (A-1-2) may be used.
Further, as the compound that provides the structural unit (A-1), a combination of a compound that provides the structural unit (A-1-1) and a compound that provides the structural unit (A-1-2) may be used.

The tetracarboxylic acid component preferably contains 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 99 mol%, of the compound that gives the structural unit (A-1). Including above. The upper limit of the content of the compound giving the structural unit (A-1) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist only of a compound that provides the structural unit (A-1).

The tetracarboxylic acid component may include a compound other than the compound that provides the structural unit (A-1). Examples of the compound include the above-described aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, And aliphatic tetracarboxylic dianhydrides, and derivatives thereof (tetracarboxylic acid, alkyl esters of tetracarboxylic acid, etc.).
The compound other than the compound giving the structural unit (A-1) optionally contained in the tetracarboxylic acid component may be one kind or two or more kinds.

As a preferred embodiment of the compound other than the compound giving the structural unit (A-1), a compound giving the structural unit (A-2) can be mentioned.
Examples of the compound that provides the structural unit (A-2) include compounds represented by the formula (a-2), but are not limited thereto, and may be derivatives thereof within a range that provides the same structural unit. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-2), and an alkyl ester of the tetracarboxylic acid. As the compound giving the structural unit (A-2), a compound represented by the formula (a-2) (that is, dianhydride) is preferable.
When the tetracarboxylic acid component includes a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2), the tetracarboxylic acid component is preferably a compound that provides the structural unit (A-1). -95 mol%, more preferably 70-95 mol%, more preferably 85-95 mol%, and the compound giving the structural unit (A-2) is preferably contained in an amount of 5-50 mol%, more preferably 5 to 30 mol% is contained, more preferably 5 to 15 mol%.
The tetracarboxylic acid component may consist only of a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2).

Examples of the compound that provides the structural unit (B-1) include compounds represented by the formula (b-1), but are not limited thereto, and may be derivatives thereof within a range that provides the same structural unit. Examples of the derivative include diisocyanates corresponding to the diamine represented by the formula (b-1). As the compound that gives the structural unit (B-1), a compound represented by the formula (b-1) (that is, a diamine) is preferable.
Examples of the compound that provides the structural unit (B-2) include compounds represented by the formula (b-2), but are not limited thereto, and may be derivatives thereof within a range that provides the same structural unit. Examples of the derivative include diisocyanates corresponding to the diamine represented by the formula (b-2). As the compound that gives the structural unit (B-2), a compound represented by the formula (b-2) (that is, a diamine) is preferable.

The diamine component preferably contains 40 to 99 mol%, more preferably 45 to 95 mol%, still more preferably 75 to 95 mol%, and particularly preferably 80 to 99 mol% of the compound giving the structural unit (B-1). Contains 90 mol%.
The diamine component preferably contains 1 to 60 mol%, more preferably 5 to 55 mol%, still more preferably 5 to 25 mol%, particularly preferably 10 to 10 mol% of the compound giving the structural unit (B-2). Contains 20 mol%.
The diamine component contains a total of the compound that provides the structural unit (B-1) and the compound that provides the structural unit (B-2), preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol%. It contains at least mol%, particularly preferably at least 99 mol%. The upper limit of the total content of the compound that provides the structural unit (B-1) and the compound that provides the structural unit (B-2) is not particularly limited, that is, 100 mol%. The diamine component may consist only of a compound that provides the structural unit (B-1) and a compound that provides the structural unit (B-2).

The diamine component may include a compound other than the compound that provides the structural unit (B-1) and the compound that provides the structural unit (B-2). Examples of the compound include the aromatic diamine, alicyclic diamine, and fatty acid described above. Group diamines, and derivatives thereof (such as diisocyanates).
The compound other than the compound giving the structural unit (B-1) and the compound giving the structural unit (B-2) optionally contained in the diamine component may be one kind or two or more kinds.

In the present invention, the charging ratio of the tetracarboxylic acid component and the diamine component used for the production of the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component relative to 1 mol of the tetracarboxylic acid component.

In the present invention, for the production of the polyimide resin, a terminal blocking agent may be used in addition to the aforementioned tetracarboxylic acid component and diamine component. As end-capping agents, monoamines or dicarboxylic acids are preferred. The amount of the terminal blocking agent introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, per 1 mol of the tetracarboxylic acid component. Examples of monoamine end-capping agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3- Ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline and the like are recommended. Of these, benzylamine and aniline can be preferably used. As the dicarboxylic acid end-capping agent, dicarboxylic acids are preferable, and a part of them may be closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2 -Dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid and the like are recommended. Of these, phthalic acid and phthalic anhydride can be suitably used.

There is no restriction | limiting in particular in the method of making the above-mentioned tetracarboxylic acid component and a diamine component react, A well-known method can be used.
Specifically, (1) a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then heated to imidize. Method of performing the reaction, (2) The diamine component and the reaction solvent are charged into the reactor and dissolved, then the tetracarboxylic acid component is charged, and if necessary, stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then (3) A method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor and the temperature is immediately raised to carry out an imidization reaction.

The reaction solvent used for the production of the polyimide resin may be any solvent that does not inhibit the imidization reaction and can dissolve the produced polyimide resin. For example, an aprotic solvent, a phenol solvent, an ether solvent, a carbonate solvent, and the like can be given.

Specific examples of aprotic solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, etc. Amide solvents, lactone solvents such as γ-butyrolactone and γ-valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide, sulfur-containing dimethylsulfone, dimethylsulfoxide, sulfolane and the like And solvents such as ketone solvents such as acetone, cyclohexanone and methylcyclohexanone, amine solvents such as picoline and pyridine, and ester solvents such as acetic acid (2-methoxy-1-methylethyl).

Specific examples of the phenol solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4 -Xylenol, 3,5-xylenol and the like.
Specific examples of ether solvents include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethyl]. Examples include ether, tetrahydrofuran, 1,4-dioxane and the like.
Specific examples of the carbonate solvent include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and the like.
Among the above reaction solvents, amide solvents or lactone solvents are preferable. Moreover, you may use said reaction solvent individually or in mixture of 2 or more types.

In the imidization reaction, it is preferable to perform the reaction using a Dean-Stark apparatus or the like while removing water generated during production. By performing such an operation, the degree of polymerization and the imidization rate can be further increased.

In the above imidation reaction, a known imidation catalyst can be used. Examples of the imidization catalyst include a base catalyst and an acid catalyst.
Base catalysts include pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N, N -Organic base catalysts such as dimethylaniline and N, N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate.
Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. Is mentioned. The above imidation catalysts may be used alone or in combination of two or more.
Among these, from the viewpoint of handleability, it is preferable to use a base catalyst, more preferably an organic base catalyst, still more preferably triethylamine, and particularly preferably a combination of triethylamine and triethylenediamine.

The temperature of the imidization reaction is preferably 120 to 250 ° C., more preferably 160 to 200 ° C., from the viewpoint of suppressing the reaction rate and gelation. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

<Crosslinking agent>
In the present invention, the crosslinking agent has at least two oxazolyl groups. That is, the crosslinking agent in the present invention is a polyfunctional oxazoline compound having two or more oxazolyl groups (oxazoline rings) in the molecule.
The oxazolyl group has reactivity with a carboxyl group, and when the carboxyl group reacts with the oxazolyl group, an amide ester bond is formed as shown below. This reaction is particularly likely to proceed when heated to 80 ° C. or higher.

Since the polyimide resin contained in the polyimide resin composition of the present invention has a carboxyl group, when the polyimide resin composition of the present invention is heated, the polyimide resins are cross-linked via a cross-linking agent to form a cross-linked polyimide resin. The For these reasons, the organic solvent resistance of the film is improved. In addition, since the reaction between the oxazolyl group and the carboxyl group hardly proceeds at room temperature, the polyimide resin composition of the present invention is excellent in storage stability.

The crosslinking agent is not particularly limited as long as it is a compound having two or more oxazolyl groups in the molecule. Specific examples thereof include 1,3-bis (4,5-dihydro-2-oxazolyl) benzene, 1,4 -Bis (4,5-dihydro-2-oxazolyl) benzene, 2,2'-bis (2-oxazoline), K-2010E, K-2020E, K-2030E, 2,6-bis manufactured by Nippon Shokubai Co., Ltd. (4-Isopropyl-2-oxazolin-2-yl) pyridine, 2,6-bis (4-phenyl-2-oxazolin-2-yl) pyridine, 2,2′-isopropylidenebis (4-phenyl-2-) Oxazoline), 2,2′-isopropylidenebis (4-tert-butyl-2-oxazoline) and the like.
The cross-linking agent is preferably a compound containing an aromatic ring or aromatic heterocyclic ring to which at least two oxazolyl groups are bonded, more preferably a compound containing a benzene ring to which at least two oxazolyl groups are bonded, and more preferably 1,3-bis (4,5-dihydro-2-oxazolyl) benzene.
A crosslinking agent may be used independently and may be used in combination of 2 or more types.

The polyimide resin composition of the present invention is such that the molar ratio of the oxazolyl group in the crosslinking agent to the carboxyl group in the polyimide resin (oxazolyl group / carboxyl group) is in the range of 1/4 to 1 / 0.5. In this case, it is preferable to include a polyimide resin and a crosslinking agent. The molar ratio is more preferably 1/4 to 1/1, still more preferably 1/2 to 1/1.
The above molar ratio means the molar ratio between the oxazolyl group contained in the crosslinking agent and the carboxyl group contained in the compound that gives the structural unit (B-2) used in the production of the polyimide resin. The amount is calculated based on the amount of compound added to give the structural unit (B-2).

As a suitable one aspect | mode of the polyimide resin composition of this invention, in addition to the above-mentioned polyimide resin and the above-mentioned crosslinking agent, the polyimide resin composition further contains the organic solvent and the said polyimide resin is melt | dissolving in the said organic solvent ( Hereinafter, it is also referred to as “polyimide varnish”).
The organic solvent is not particularly limited as long as it dissolves the polyimide resin, but it is preferable to use the above-described compounds alone or in combination of two or more as the reaction solvent used in the production of the polyimide resin.
The polyimide varnish may be obtained by adding a crosslinking agent to a solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or a solution obtained by adding a dilution solvent and a crosslinking agent to the solution. It may be.

The above-mentioned polyimide resin has solvent solubility, and the crosslinking reaction with the crosslinking agent hardly proceeds at room temperature. Therefore, a highly concentrated polyimide varnish stable at room temperature can be obtained. The polyimide varnish preferably contains 5 to 40% by mass of polyimide resin, more preferably 10 to 30% by mass. The viscosity of the polyimide varnish is preferably 1 to 200 Pa · s, more preferably 5 to 150 Pa · s. The viscosity of the polyimide varnish is a value measured at 25 ° C. using an E-type viscometer.

Moreover, the polyimide resin composition of the present invention is an inorganic filler, an adhesion promoter, a release agent, a flame retardant, an ultraviolet stabilizer, a surfactant, a leveling agent, an antifoaming agent, as long as the required properties of the polyimide film are not impaired. Various additives such as a fluorescent brightener, a crosslinking agent, a polymerization initiator, and a photosensitizer may be included.
The manufacturing method of the polyimide resin composition of this invention is not specifically limited, A well-known method is applicable.

The polyimide resin composition of the present invention can form a film having excellent mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy. Suitable physical properties of the film that can be formed using the polyimide resin composition of the present invention are as follows.

The tensile strength is preferably 50 MPa or more, more preferably 60 MPa or more, and further preferably 70 MPa or more.
The tensile elastic modulus is preferably 2.0 GPa or more, more preferably 2.2 GPa or more, and further preferably 2.5 GPa or more.
The total light transmittance is preferably 87% or more, more preferably 88% or more, and even more preferably 89% or more when a film having a thickness of 10 μm is formed.
The yellow index (YI) is preferably 6.8 or less, more preferably 3.5 or less, and even more preferably 2.2 or less when a film having a thickness of 10 μm is formed.
The absolute value of the thickness retardation (Rth) is preferably 75 nm or less, more preferably 25 nm or less, and even more preferably 10 nm or less when a film having a thickness of 10 μm is formed.
The tensile strength, tensile elastic modulus, total light transmittance, yellow index (YI), and thickness retardation (Rth) in the present invention can be specifically measured by the methods described in the examples.

[Polyimide film]
The polyimide film of the present invention is formed by crosslinking the above polyimide resin contained in the polyimide resin composition of the present invention with the above crosslinking agent. That is, the polyimide film of the present invention includes a crosslinked polyimide resin that is a crosslinked product of polyimide resins with a crosslinking agent interposed therebetween. Therefore, the polyimide film of the present invention is excellent in mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy. The preferred physical properties of the polyimide film of the present invention are as described above.
The method for producing a polyimide film of the present invention includes a step of crosslinking at a temperature (preferably 80 ° C. or higher, more preferably 100 ° C. or higher, more preferably 150 ° C. or higher) at which a cross-linking reaction between the polyimide resin and the cross-linking agent proceeds. If included, there is no particular limitation. For example, the above-mentioned polyimide varnish is applied on a smooth support such as a glass plate, a metal plate, or plastic, or formed into a film and then heated. By this heat treatment, an organic solvent such as a reaction solvent or a diluting solvent contained in the polyimide varnish can be removed while a crosslinking reaction between the polyimide resin in the polyimide varnish and the crosslinking agent proceeds. If necessary, a release agent may be applied to the surface of the support in advance.
Examples of the method for applying the polyimide varnish on the support include known coating methods such as spin coating, slit coating, and blade coating.
As the heat treatment, the following method is preferable. That is, after evaporating the organic solvent at a temperature of 60 to 150 ° C. to obtain a self-supporting film, the self-supporting film is peeled off from the support, the end of the self-supporting film is fixed, and the organic solvent used It is preferable to produce a polyimide film by drying at a temperature equal to or higher than the boiling point of the solvent. Moreover, it is preferable to dry in nitrogen atmosphere. The pressure in the dry atmosphere may be any of reduced pressure, normal pressure, and increased pressure. The heating temperature for producing the polyimide film by drying the self-supporting film is not particularly limited, but is preferably 250 to 400 ° C.

The thickness of the polyimide film of the present invention can be appropriately selected depending on the application and the like, but is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, still more preferably 10 to 80 μm. When the thickness is 1 to 250 μm, practical use as a self-supporting film becomes possible.
The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish.

The polyimide film of the present invention is suitably used as a film for various members such as a color filter, a flexible display, a semiconductor component, and an optical member. The polyimide film of the present invention is particularly preferably used as a substrate for image display devices such as liquid crystal displays and OLED displays.

Hereinafter, the present invention will be described specifically by way of examples. However, this invention is not restrict | limited at all by these Examples.

The solid content concentration of the polyimide resin solutions and polyimide varnishes obtained in the examples and comparative examples and the physical properties of the polyimide film were measured by the following methods.
(1) Solid content concentration The solid content concentration of the polyimide resin solution and the polyimide varnish was measured by heating the sample at 320 ° C. × 120 min in a small electric furnace “MMF-1” manufactured by ASONE Co., Ltd., and the mass of the sample before and after heating. Calculated from the difference.
(2) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Corporation.
(3) Tensile strength and tensile modulus The measurement was performed according to JIS K7127 using a tensile tester “Strograph VG-1E” manufactured by Toyo Seiki Co., Ltd.
(4) Total light transmittance, yellow index (YI)
The measurement was performed according to JIS K7361-1, using a color / turbidity simultaneous measuring device “COH400” manufactured by Nippon Denshoku Industries Co., Ltd.
(5) Thickness retardation (Rth)
The thickness retardation (Rth) was measured using an ellipsometer “M-220” manufactured by JASCO Corporation. The thickness retardation value at a measurement wavelength of 590 nm was measured. Rth is expressed by the following formula when the maximum refractive index in the plane of the polyimide film is nx, the minimum refractive index is ny, the refractive index in the thickness direction is nz, and the thickness of the film is d. Is.
Rth = [{(nx + ny) / 2} -nz] × d
(6) Organic solvent resistance The obtained film was immersed in an organic solvent at 60 ° C for 3 hours to evaluate the organic solvent resistance. Note that N-methyl-2-pyrrolidone (NMP) was used as the organic solvent.
The evaluation criteria for organic solvent resistance were as follows.
B: The film surface was dissolved in less than 3 hours after immersion in an organic solvent.
A: Even after 3 hours of immersion in an organic solvent, the film surface did not dissolve and no change was observed.

The tetracarboxylic acid component, diamine component, crosslinking agent, and abbreviations used in the examples and comparative examples are as follows.
<Tetracarboxylic acid component>
HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (Mitsubishi Gas Chemical Co., Ltd .; compound represented by formula (a-1-1))
CpODA: Norbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic dianhydride (manufactured by JX Energy Corporation; Compound represented by formula (a-1-2))
s-BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (Mitsubishi Chemical Corporation; compound represented by formula (a-2s))
<Diamine component>
BAFL: 9,9-bis (4-aminophenyl) fluorene (manufactured by Taoka Chemical Co., Ltd .; compound represented by formula (b-1))
3,5-DABA: 3,5-diaminobenzoic acid (Nippon Pure Chemicals Co., Ltd .; compound represented by formula (b-211))
mTB: 2,2′-dimethylbiphenyl-4,4′-diamine (manufactured by Seika Corporation)
<Crosslinking agent>
1,3-PBO: 1,3-bis (4,5-dihydro-2-oxazolyl) benzene (manufactured by Mikuni Pharmaceutical Co., Ltd.)
TG: triglycidyl isocyanurate (manufactured by Tokyo Chemical Industry Co., Ltd.)

<Example 1A>
27.766 g (0.080 mol) of BAFL in a 1 L 5-neck round bottom flask equipped with a stainless steel half-moon stirring blade, a Dean Stark fitted with a nitrogen inlet tube, a cooling tube, a thermometer, and a glass end cap And 3.43 g (0.020 mol) of 3,5-DABA and 79.242 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added, and the system temperature was 70 ° C. under a nitrogen atmosphere at a rotation speed of 200 rpm. Stir to give a solution.
To this solution, 22.417 g (0.100 mol) of HPMDA and 19.811 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) as an imidization catalyst. 0.506 g was added and heated with a mantle heater, and the reaction system internal temperature was raised to 190 ° C. over about 20 minutes. The component to be distilled off was collected, and the temperature in the reaction system was maintained at 190 ° C. and refluxed for 3 hours while adjusting the number of rotations according to the increase in viscosity.
Thereafter, 351.779 g of γ-butyrolactone (Mitsubishi Chemical Co., Ltd.) was added and the reaction system internal temperature was cooled to 120 ° C., followed by further stirring for about 3 hours to homogenize, and a solid content concentration of 10.0 mass. % Polyimide resin solution (1) was obtained.
Subsequently, 0.216 g (0.001 mol) of 1,3-PBO as a crosslinking agent is added to 100 g of the polyimide resin solution (1), and the mixture is stirred for 1 hour at room temperature, and then contains the crosslinking agent and the polyimide resin. A polyimide varnish having a solid content concentration of 10.2% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80 ° C. for 20 minutes on a hot plate, and then heated at 350 ° C. for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, An 18 μm film was obtained. The results are shown in Table 1.

<Example 1B>
A polyimide varnish was prepared in the same manner as in Example 1A, except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (1) was changed to 0.432 g (0.002 mol). A polyimide varnish having a solid content concentration of 10.4% by mass containing an agent and a polyimide resin was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1A to obtain a film having a thickness of 17 μm. The results are shown in Table 1.

<Comparative Example 1>
A polyimide varnish was produced in the same manner as in Example 1A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (1). That is, the polyimide resin solution (1) was used as it was as a polyimide varnish.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1A to obtain a film having a thickness of 16 μm. The results are shown in Table 1.

<Example 2A>
31.361 g (0.090 mol) of BAFL in a 1 L 5-neck round bottom flask equipped with a stainless steel half-moon stirring blade, a Dean Stark fitted with a nitrogen inlet tube, a cooling tube, a thermometer, and a glass end cap And 1.522 g (0.010 mol) of 3,5-DABA and 105.961 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were charged at a system temperature of 70 ° C. under a nitrogen atmosphere at a rotation speed of 200 rpm. Stir to give a solution.
To this solution, 38.438 g (0.100 mol) of CpODA and 26.490 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was used as an imidization catalyst. 0.506 g and 0.056 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and heated with a mantle heater, and the reaction system temperature was raised to 190 ° C. over about 20 minutes. The component to be distilled off was collected, and the temperature in the reaction system was maintained at 190 ° C. and refluxed for 3 hours while adjusting the number of rotations according to the increase in viscosity.
Thereafter, 478.614 g of γ-butyrolactone (Mitsubishi Chemical Co., Ltd.) was added and the reaction system internal temperature was cooled to 120 ° C., followed by further stirring for about 3 hours to homogenize and a solid content concentration of 10.0 mass. % Polyimide resin solution (2) was obtained.
Subsequently, 0.0796 g (0.00037 mol) of 1,3-PBO as a crosslinking agent was added to 100 g of the polyimide resin solution (2), and the mixture was stirred at room temperature for 1 hour, and then the crosslinking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 10.07% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80 ° C. for 20 minutes on a hot plate, and then heated at 350 ° C. for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, A 27 μm film was obtained. The results are shown in Table 1.

<Example 2B>
A polyimide varnish was prepared in the same manner as in Example 2A except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (2) was changed to 0.1592 g (0.00074 mol). A polyimide varnish having a solid content concentration of 10.14% by mass containing an agent and a polyimide resin was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 2A to obtain a film having a thickness of 23 μm. The results are shown in Table 1.

<Comparative Example 2>
A polyimide varnish was produced in the same manner as in Example 2A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (2). That is, the polyimide resin solution (2) was used as it was as a polyimide varnish.
Using the obtained polyimide varnish, a film was prepared in the same manner as in Example 2A to obtain a film having a thickness of 14 μm. The results are shown in Table 1.

<Example 3A>
The amount of BAFL was changed from 31.361 g (0.090 mol) to 27.876 g (0.080 mol), and the amount of 3,5-DABA was changed from 1.522 g (0.010 mol) to 3.043 g (0 A polyimide resin solution was prepared in the same manner as in Example 2A except that the content was changed to 0.020 mol) to obtain a polyimide resin solution (3) having a solid content concentration of 10.0% by mass.
Subsequently, 0.159 g (0.0007 mol) of 1,3-PBO as a crosslinking agent was added to 100 g of the polyimide resin solution (3), and the mixture was stirred at room temperature for 1 hour, and then the crosslinking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 10.14% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/2.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 2A to obtain a film having a thickness of 24 μm. The results are shown in Table 1.
<Example 3B>
A polyimide varnish was prepared in the same manner as in Example 3A, except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (3) was changed to 0.319 g (0.0015 mol). A polyimide varnish having a solid content concentration of 10.29% by mass containing an agent and a polyimide resin was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 3A to obtain a film having a thickness of 23 μm. The results are shown in Table 1.

<Comparative Example 3>
A polyimide varnish was produced in the same manner as in Example 3A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (3). That is, the polyimide resin solution (3) was used as it was as a polyimide varnish.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 3A to obtain a film having a thickness of 20 μm. The results are shown in Table 1.

<Example 4A>
The amount of BAFL was changed from 31.361 g (0.090 mol) to 17.423 g (0.050 mol), and the amount of 3,5-DABA was changed from 1.522 g (0.010 mol) to 7.608 g (0 Except for changing to .050 mol), a polyimide resin solution was prepared in the same manner as in Example 2A to obtain a polyimide resin solution (4) having a solid concentration of 10.0% by mass.
Subsequently, 0.445 g (0.0021 mol) of 1,3-PBO as a crosslinking agent was added to 100 g of the polyimide resin solution (4), and the mixture was stirred at room temperature for 1 hour, and then the crosslinking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 10.40% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/2.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 2A to obtain a film having a thickness of 12 μm. The results are shown in Table 1.
<Example 4B>
A polyimide varnish was prepared in the same manner as in Example 4A, except that the amount of the crosslinking agent 1,3-PBO added to the polyimide resin solution (4) was changed to 0.890 g (0.0041 mol). A polyimide varnish having a solid content concentration of 10.79% by mass containing an agent and a polyimide resin was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
A film having a thickness of 15 μm was obtained using the obtained polyimide varnish by the same method as in Example 4A. The results are shown in Table 1.

<Comparative Example 4>
A polyimide varnish was produced in the same manner as in Example 4A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (4). That is, the polyimide resin solution (4) was used as it was as a polyimide varnish.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 4A to obtain a film having a thickness of 20 μm. The results are shown in Table 1.

<Example 5>
The same method as in Example 1A, except that the amount of HPMDA was changed from 22.417 g (0.100 mol) to 11.209 g (0.050 mol), and 19.219 g (0.050 mol) of CpODA was added. To prepare a polyimide resin solution, and a polyimide resin solution (5) having a solid content concentration of 10.0% by mass was obtained.
Subsequently, 0.372 g (0.0017 mol) of 1,3-PBO as a cross-linking agent was added to 100 g of the polyimide resin solution (5), and after stirring for 1 hour at room temperature, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 10.33% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
A film having a thickness of 9 μm was obtained using the obtained polyimide varnish by the same method as in Example 1A. The results are shown in Table 1.

<Comparative Example 5>
A polyimide varnish was produced in the same manner as in Example 5 except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (5). That is, the polyimide resin solution (5) was used as it was as a polyimide varnish.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 5 to obtain a film having a thickness of 9 μm. The results are shown in Table 1.

<Example 6>
Same as Example 1A except that the amount of HPMDA was changed from 22.417 g (0.100 mol) to 20.175 g (0.090 mol) and 2.942 g (0.010 mol) of s-BPDA was added. A polyimide resin solution was prepared by the above method to obtain a polyimide resin solution (6) having a solid content concentration of 10.0% by mass.
Subsequently, 0.424 g (0.0020 mol) of 1,3-PBO as a crosslinking agent was added to 100 g of the polyimide resin solution (6), and the mixture was stirred at room temperature for 1 hour, and then the crosslinking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 10.38% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 1A to obtain a film having a thickness of 20 μm. The results are shown in Table 1.

<Comparative Example 6>
A polyimide varnish was produced in the same manner as in Example 6 except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (6). That is, the polyimide resin solution (6) was used as it was as a polyimide varnish.
Using the obtained polyimide varnish, a film was produced in the same manner as in Example 6 to obtain a film having a thickness of 17 μm. The results are shown in Table 1.

<Comparative Example 7A>
Except that the cross-linking agent added to the polyimide resin solution (1) was changed from 0.216 g (0.001 mol) of 1,3-PBO to 0.500 g (0.0017 mol) of TG. A polyimide varnish was prepared in the same manner as in Example 1A, and a polyimide varnish containing a crosslinking agent and a polyimide resin and having a solid content concentration of 10.45% by mass was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80 ° C. for 20 minutes on a hot plate, and then heated at 350 ° C. for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, A 20 μm film was obtained. The obtained film had point defects on the entire surface. The results are shown in Table 2.

<Comparative Example 7B>
A polyimide varnish was prepared in the same manner as in Comparative Example 7A except that the amount of the crosslinking agent TG added to the polyimide resin solution (1) was changed to 1.000 g (0.0034 mol). A polyimide varnish having a solid content concentration of 10.89% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner as in Comparative Example 7A to obtain a film having a thickness of 22 μm. The obtained film had point defects on the entire surface. The results are shown in Table 2.

<Comparative Example 8A>
10.615 g (0.050 mol) of mTB in a 1 L 5-neck round bottom flask equipped with a stainless steel half-moon stirrer, a nitrogen inlet tube, a Dean Stark fitted with a cooling tube, a thermometer, and a glass end cap Then, 7.608 g (0.050 mol) of 3,5-DABA and 48.767 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70 ° C. under a nitrogen atmosphere at a rotation speed of 200 rpm. Stir to give a solution.
To this solution, HPDDA (22.417 g, 0.100 mol) and N, N′-dimethylacetamide (Mitsubishi Gas Chemical Co., Ltd.) (12.192 g) were added all at once, and then triethylamine ( 0.506 g of Kanto Chemical Co., Inc.) was added and heated with a mantle heater, and the temperature in the reaction system was raised to 180 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 180 ° C. and refluxed for 5 hours while adjusting the rotation speed in accordance with the increase in viscosity.
Thereafter, 280.466 g of N, N′-dimethylacetamide (Mitsubishi Gas Chemical Co., Ltd.) was added and the reaction system internal temperature was cooled to 120 ° C., followed by further stirring for about 3 hours to homogenize the solid content. A polyimide resin solution (7) having a concentration of 10.0% by mass was obtained.
Subsequently, 1.425 g (0.0066 mol) of 1,3-PBO as a crosslinking agent was added to 100 g of the polyimide resin solution (7), and the mixture was stirred at room temperature for 1 hour, and then the crosslinking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 11.26% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the added amount of 1,3-PBO and the added amount of 3,5-DABA is 1/1.
Subsequently, the obtained polyimide varnish was applied onto a glass plate, held at 80 ° C. for 20 minutes on a hot plate, and then heated at 350 ° C. for 30 minutes in a hot air dryer under a nitrogen atmosphere to evaporate the solvent, A 16 μm film was obtained. The results are shown in Table 3.

<Comparative Example 8B>
A polyimide varnish was produced in the same manner as in Comparative Example 8A, except that the crosslinking agent 1,3-PBO was not added to the polyimide resin solution (7). That is, the polyimide resin solution (7) was used as it was as a polyimide varnish.
A film having a thickness of 15 μm was obtained using the obtained polyimide varnish by the same method as in Comparative Example 8A. The results are shown in Table 3.

As shown in Table 1, the films of the examples were all excellent in mechanical properties, organic solvent resistance, colorless transparency, and optical isotropy.
In particular, it was confirmed that organic solvent resistance was improved by adding 1,3-PBO (contrast between Examples 1A and 1B and Comparative Example 1, Examples 2A and 2B and Comparative Example 2). Comparison, Comparison between Examples 3A and 3B and Comparative Example 3, Comparison between Examples 4A and 4B and Comparative Example 4, Comparison between Example 5 and Comparative Example 5, and Comparison between Example 6 and Comparative Example 6 ).
Surprisingly, even if 1,3-PBO is added, the optical isotropy can be maintained (contrast between Examples 1A and 1B and Comparative Example 1), or by adding 1,3-PBO. Optical isotropy is improved (Comparison between Examples 2A and 2B and Comparative Example 2, Comparison between Examples 3A and 3B and Comparative Example 3, Comparison between Examples 4A and 4B and Comparative Example 4, Example 5 and comparison example 5 and comparison between example 6 and comparison example 6).

The films obtained in Comparative Examples 7A and 7B using TG (not a crosslinking agent having at least two oxazolyl groups) as a crosslinking agent were not uniform films. This is probably because the compatibility between the polyimide resin and the additive TG is poor and separated.
Further, as shown in Table 2, the film of Comparative Example 7B was greatly inferior in colorless transparency.

In Comparative Examples 8A and 8B, BAFL (a compound represented by the formula (b-1)) was not used as a diamine component, and mTB was used instead. As a result, the films of Comparative Examples 8A and 8B obtained were inferior in optical isotropy. Moreover, the film of Comparative Example 8B was inferior in organic solvent resistance. As can be seen by comparing Comparative Example 8A with Comparative Example 8B, the addition of 1,3-PBO improved the organic solvent resistance, but significantly reduced the colorless transparency (total light transmittance, YI). . As a result, the film of Comparative Example 8A was significantly inferior in colorless transparency as compared with the film of Examples.

Claims (9)

A polyimide resin composition comprising a polyimide resin and a crosslinking agent having at least two oxazolyl groups,
The polyimide resin has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,
The structural unit A is derived from a structural unit (A-1-1) derived from a compound represented by the following formula (a-1-1) and a compound represented by the following formula (a-1-2). Comprising at least one structural unit (A-1) selected from the group consisting of units (A-1-2),
The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1) and a structural unit (B-2 derived from a compound represented by the following formula (b-2). And a polyimide resin composition.

(In the formula (b-1), each R is independently a hydrogen atom, a fluorine atom or a methyl group; in the formula (b-2), X is a single bond, a substituted or unsubstituted alkylene group, a carbonyl A group, an ether group, a group represented by the following formula (b-2-i), or a group represented by the following formula (b-2-ii), p is an integer of 0 to 2, and m1 is (It is an integer from 0 to 4, and m2 is an integer from 0 to 4. However, when p is 0, m1 is an integer from 1 to 4.)

(In the formula (b-2-i), m3 is an integer of 0 to 5; in the formula (b-2-ii), m4 is an integer of 0 to 5. Note that m1 + m2 + m3 + m4 is 1 or more. When p is 2, each of the two X and the two m2 to m4 is independently selected.) The polyimide resin composition according to claim 1, wherein the structural unit (B-2) is a structural unit (B-21) derived from a compound represented by the following formula (b-21).

The polyimide resin composition according to claim 1 or 2, wherein the crosslinking agent comprises a benzene ring to which the at least two oxazolyl groups are bonded. In a ratio such that the molar ratio of the oxazolyl group in the crosslinking agent to the carboxyl group in the polyimide resin (oxazolyl group / carboxyl group) is in the range of 1/4 to 1 / 0.5, the polyimide resin and the The polyimide resin composition according to any one of claims 1 to 3, comprising a crosslinking agent. The ratio of the structural unit (B-1) in the structural unit B is 40 to 99 mol%,
5. The polyimide resin composition according to claim 1, wherein the proportion of the structural unit (B-2) in the structural unit B is 1 to 60 mol%. 6. The polyimide resin composition according to claim 1, wherein the proportion of the structural unit (A-1) in the structural unit A is 50 mol% or more. The polyimide resin composition according to any one of claims 1 to 6, wherein the structural unit (A-1) is the structural unit (A-1-1). The polyimide resin composition according to any one of claims 1 to 6, wherein the structural unit (A-1) is the structural unit (A-1-2). A polyimide film obtained by crosslinking the polyimide resin in the polyimide resin composition according to any one of claims 1 to 8 with the crosslinking agent.