JPWO2020121949A1 - Polyimide resin composition and polyimide film - Google Patents

Abstract

A polyimide resin composition containing a polyimide resin and a cross-linking agent having at least two oxazolyl groups, wherein the polyimide resin contains a structural unit A derived from tetracarboxylic acid dianhydride and a structural unit B derived from diamine. The constituent unit A includes the constituent unit (A-1) derived from the compound represented by the following formula (a-1), and the constituent unit B is the compound represented by the following formula (b-1). Derived from the structural unit (B-1) derived from, the structural unit (B-2) derived from the compound represented by the following formula (b-2), and the compound represented by the following formula (b-3). A polyimide resin composition containing the structural unit (B-3), and a polyimide film obtained by cross-linking the polyimide resin in the polyimide resin composition with the cross-linking agent. (In equation (b-1), 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; In formula (b-2), R1 to R4 are independently monovalent aliphatic groups or monovalent aromatic groups, and Z1 and Z2 are independently divalent aliphatic groups, respectively. Or a divalent aromatic group, where r is a positive integer.)

Description

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

Since the polyimide resin has excellent mechanical properties and heat resistance, various uses are being studied in the fields of electrical and electronic parts and the like. For example, it is desired to replace a glass substrate used in 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 and flexibility of the device. Research is underway. Colorless transparency is required for polyimide films for such applications.

As a polyimide film suitable for the above application, a polyimide film produced by adding a cross-linking 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 cross-linking agent having at least two oxazolyl groups, and the polyimide resin composition provides a film having good transparency and high hardness. It is stated that the formation of is possible.

Japanese Unexamined Patent Publication No. 2016-222777

In an image display device, when light emitted from a display element is emitted through a plastic substrate, colorless transparency is required for the plastic substrate, and light passes through a retardation film or a polarizing plate ( For example, liquid crystal displays, touch panels, etc.) are required to have high optical isotropic properties in addition to colorless transparency. However, Patent Document 1 does not describe any optical isotropic property.

Further, in order for the polyimide film to be suitable as a substrate, chemical resistance (solvent resistance and acid resistance) is also required. For example, when a varnish for forming the resin layer is applied to the polyimide film in order to form another resin layer (for example, a color filter or a resist) on the polyimide film, the polyimide film contains a solvent contained in the varnish. Resistance to is required. If the solvent resistance of the polyimide film is insufficient, it may become meaningless as a substrate due to dissolution or swelling of the film.
Further, when the polyimide film is used as a substrate for forming an ITO (Indium Tin Oxide) film, the polyimide film is required to have resistance to the acid used for etching the ITO film. If the acid resistance of the polyimide film is insufficient, the film may turn yellow and the colorless transparency may be impaired.
In Patent Document 1, resistance to a solvent (N, N-dimethylacetamide) has been evaluated, but acid resistance has not been evaluated.

Further, depending on the combination of the polyimide resin and the cross-linking agent, the polyimide resin composition containing the polyimide resin and the cross-linking agent may undergo gelation due to cross-linking even when stored at room temperature. Not suitable.
Further, the polyimide resin composition is also required to have solubility in a cleaning solution (for example, "OK73 thinner" manufactured by Tokyo Ohka Kogyo Co., Ltd.) used for piping and equipment used for coating the polyimide resin composition and the like. If the solubility in the cleaning solution is low, the cleaning of piping and equipment with the cleaning solution may be insufficient.
Patent Document 1 does not describe any storage stability or detergency of the polyimide resin composition.

The present invention has been made in view of the above circumstances, and an object of the present invention is that it is possible to form a film having excellent colorless transparency, optical isotropic property, and chemical resistance (solvent resistance and acid resistance). It is an object of the present invention to provide a polyimide resin composition having excellent storage stability and cleanability, and to provide a polyimide film obtained by cross-linking the polyimide resin in the polyimide resin composition with a cross-linking agent.

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

（式（ｂ−１）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−１−ｉ）で表される基、又は下記式（ｂ−１−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。

［式（ｂ−１−ｉ）中、ｍ３は０〜５の整数であり、式（ｂ−１−ｉｉ）中、ｍ４は０〜５の整数である。］
ただし、
ｍ１＋ｍ２＋ｍ３＋ｍ４は１以上であり、
ｐが０の場合、ｍ１は１〜４の整数であり、
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；
式（ｂ−２）中、
Ｒ¹〜Ｒ⁴は、それぞれ独立して、一価の脂肪族基又は一価の芳香族基であり、
Ｚ¹及びＺ²は、それぞれ独立して、二価の脂肪族基又は二価の芳香族基であり、
ｒは正の整数である。）That is, the present invention relates to the following [1] to [11].
[1]
A polyimide resin composition containing a polyimide resin and a cross-linking 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 includes a structural unit (A-1) derived from a compound represented by the following formula (a-1).
The structural unit B is 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 the structural unit (B-3) derived from the compound represented by the following formula (b-3).

(In equation (b-1),
X is a single bond, substituted or unsubstituted alkylene group, carbonyl group, ether group, a group represented by the following formula (b-1-i), or a group represented by the following formula (b-1-ii). can be,
p is an integer from 0 to 2
m1 is an integer from 0 to 4,
m2 is an integer from 0 to 4.

[In the formula (b-1-i), m3 is an integer of 0 to 5, and in the formula (b-1-ii), m4 is an integer of 0 to 5. ]
However,
m1 + m2 + m3 + m4 is 1 or more,
When p is 0, m1 is an integer of 1 to 4.
When p is 2, each of the two Xs and the two m2 to m4 is independently selected;
In equation (b-2),
R ^{1 to} R ⁴ are independently monovalent aliphatic groups or monovalent aromatic groups, respectively.
Z ¹ and Z ² are independently divalent aliphatic groups or divalent aromatic groups, respectively.
r is a positive integer. )

［３］
前記架橋剤が、少なくとも２つのオキサゾリル基が結合した芳香環又は芳香族複素環を含む化合物である、上記［１］又は［２］に記載のポリイミド樹脂組成物。
［４］
前記架橋剤が、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化合物である、上記［３］に記載のポリイミド樹脂組成物。
［５］
前記架橋剤が、１，３−ビス（４，５−ジヒドロ−２−オキサゾリル）ベンゼンである、上記［４］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Ｂ中における構成単位（Ｂ−１）の比率が２０〜７５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１〜２５モル％であり、
構成単位Ｂ中における構成単位（Ｂ−３）の比率が２０〜７５モル％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が、下記式（ａ−２）で表される化合物に由来する構成単位（Ａ−２）を更に含む、上記［１］〜［７］のいずれかに記載のポリイミド樹脂組成物。

［９］
構成単位Ａ中における構成単位（Ａ−１）の比率が５０〜９９モル％であり、
構成単位Ａ中における構成単位（Ａ−２）の比率が１〜５０モル％である、上記［８］に記載のポリイミド樹脂組成物。
［１０］
上記［１］〜［９］のいずれかに記載のポリイミド樹脂組成物及び有機溶媒を含むポリアミドワニス。
［１１］
上記［１］〜［９］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-1) is a structural unit (B-11) derived from a compound represented by the following formula (b-11).

[3]
The polyimide resin composition according to the above [1] or [2], wherein the cross-linking agent is a compound containing an aromatic ring or an aromatic heterocycle having at least two oxazolyl groups bonded thereto.
[4]
The polyimide resin composition according to the above [3], wherein the cross-linking agent is a compound containing a benzene ring having at least two oxazolyl groups bonded thereto.
[5]
The polyimide resin composition according to the above [4], wherein the cross-linking agent is 1,3-bis (4,5-dihydro-2-oxazolyl) benzene.
[6]
The polyimide resin composition according to any one of the above [1] to [5], wherein the ratio of the structural unit (A-1) in the structural unit A is 50 mol% or more.
[7]
The ratio of the constituent unit (B-1) in the constituent unit B is 20 to 75 mol%.
The ratio of the constituent unit (B-2) in the constituent unit B is 1 to 25 mol%.
The polyimide resin composition according to any one of the above [1] to [6], wherein the ratio of the structural unit (B-3) in the structural unit B is 20 to 75 mol%.
[8]
The polyimide resin composition according to any one of the above [1] to [7], wherein the structural unit A further contains a structural unit (A-2) derived from a compound represented by the following formula (a-2).

[9]
The ratio of the constituent unit (A-1) in the constituent unit A is 50 to 99 mol%.
The polyimide resin composition according to the above [8], wherein the ratio of the structural unit (A-2) in the structural unit A is 1 to 50 mol%.
[10]
A polyamide varnish containing the polyimide resin composition according to any one of [1] to [9] above and an organic solvent.
[11]
A polyimide film obtained by cross-linking the polyimide resin in the polyimide resin composition according to any one of [1] to [9] with the cross-linking agent.

The polyimide resin composition of the present invention is excellent in storage stability and detergency, and can form a film having excellent colorless transparency, optical isotropic property, and chemical resistance (solvent resistance and acid resistance). ..

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

<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 derived from a compound represented by the following formula (a-1). A structural unit (B-1) containing a structural unit (A-1) and whose 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). The structural unit (B-2) derived from the above and the structural unit (B-3) derived from the compound represented by the following formula (b-3) are included.

（式（ｂ−１−ｉ）中、ｍ３は０〜５の整数であり、式（ｂ−１−ｉｉ）中、ｍ４は０〜５の整数である。）
ただし、
ｍ１＋ｍ２＋ｍ３＋ｍ４は１以上であり、
ｐが０の場合、ｍ１は１〜４の整数であり、
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。In equation (b-1),
X is a single bond, substituted or unsubstituted alkylene group, carbonyl group, ether group, a group represented by the following formula (b-1-i), or a group represented by the following formula (b-1-ii). can be,
p is an integer from 0 to 2
m1 is an integer from 0 to 4,
m2 is an integer from 0 to 4.

(In the formula (b-1-i), m3 is an integer of 0 to 5, and in the formula (b-1-ii), m4 is an integer of 0 to 5.)
However,
m1 + m2 + m3 + m4 is 1 or more,
When p is 0, m1 is an integer of 1 to 4.
When p is 2, each of the two Xs and the two m2 to m4 is independently selected.

In equation (b-2),
R ^{1 to} R ⁴ are independently monovalent aliphatic groups or monovalent aromatic groups, respectively.
Z ¹ and Z ² are independently divalent aliphatic groups or divalent aromatic groups, respectively.
r is a positive integer.

(Structural unit A)
The structural unit A is a structural unit derived from the tetracarboxylic dianhydride in the polyimide resin, and includes a structural unit (A-1) derived from the compound represented by the following formula (a-1).

The compound represented by the formula (a-1) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.
When the structural unit A includes the structural unit (A-1), the colorless transparency and optical isotropic property of the film can be improved.

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, and further preferably 85 mol% or more. The upper limit 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 acid dianhydride giving such a structural unit is not particularly limited, but is pyromellitic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 9,9'. Aromatic tetracarboxylic acid dianhydrides such as −bis (3,4-dicarboxyphenyl) fluorene dianhydride and 4,4′- (hexafluoroisopropyridene) diphthalic anhydride; 1,2,3,4 -Cyclobutanetetracarboxylic dianhydride and norbornan-2-spiro-α-cyclopentanone-α'-spiro-2 "-norbornan-5,5", 6,6 "-tetracarboxylic acid dianhydride Etc., alicyclic tetracarboxylic acid dianhydride (excluding the compound represented by the formula (a-1)); and aliphatic tetra, such as 1,2,3,4-butanetetracarboxylic acid dianhydride. Carous acid dianhydride can be mentioned.
In the present specification, the aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and the alicyclic tetracarboxylic dianhydride has one alicyclic ring. It means a tetracarboxylic acid dianhydride containing the above and does not contain an aromatic ring, and the aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing neither an aromatic ring nor an alicyclic ring.
The structural unit arbitrarily included in the structural unit A (that is, the structural unit other than the structural unit (A-1)) may be one type or two or more types.

Among the above-mentioned exemplified compounds as the tetracarboxylic dianhydride which gives the structural unit arbitrarily contained in the structural unit A, 4,4'-(hexafluoroisopropyridene) diphthalic anhydride is preferable. That is, in the polyimide resin composition of one aspect of the present invention, the structural unit A of the polyimide resin further contains the structural unit (A-2) derived from the compound represented by the following formula (a-2).

When the structural unit A includes the structural unit (A-2), the optical isotropic property of the film can be further improved.

When the constituent unit A includes the constituent unit (A-1) and the constituent unit (A-2), the ratio of the constituent unit (A-1) in the constituent unit A is preferably 50 to 99 mol%, and more. It is preferably 50 to 95 mol%, more preferably 70 to 95 mol%, particularly preferably 85 to 95 mol%, and the ratio of the constituent unit (A-2) in the constituent unit A is preferably. It is 1 to 50 mol%, more preferably 5 to 50 mol%, further preferably 5 to 30 mol%, and particularly preferably 5 to 15 mol%.
The total ratio of the structural unit (A-1) and the structural unit (A-2) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol. % Or more, particularly preferably 99 mol% or more. The upper limit of the ratio of the total of the constituent units (A-1) and the constituent units (A-2) is not particularly limited, that is, 100 mol%. The structural unit A may consist only of the structural unit (A-1) and the structural unit (A-2).

(Structural unit B)
The structural unit B is a structural unit derived from a diamine in the polyimide resin, and is a structural unit (B-1) derived from a compound represented by the following formula (b-1) and the following formula (b-2). It contains a structural unit (B-2) derived from the compound represented by the following formula (b-3) and a structural unit (B-3) derived from the compound represented by the following formula (b-3).

（式（ｂ−１−ｉ）中、ｍ３は０〜５の整数であり、式（ｂ−１−ｉｉ）中、ｍ４は０〜５の整数である。）
ただし、
ｍ１＋ｍ２＋ｍ３＋ｍ４は１以上であり、
ｐが０の場合、ｍ１は１〜４の整数であり、
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。In equation (b-1),
X is a single bond, substituted or unsubstituted alkylene group, carbonyl group, ether group, a group represented by the following formula (b-1-i), or a group represented by the following formula (b-1-ii). can be,
p is an integer from 0 to 2
m1 is an integer from 0 to 4,
m2 is an integer from 0 to 4.

(In the formula (b-1-i), m3 is an integer of 0 to 5, and in the formula (b-1-ii), m4 is an integer of 0 to 5.)
However,
m1 + m2 + m3 + m4 is 1 or more,
When p is 0, m1 is an integer of 1 to 4.
When p is 2, each of the two Xs and the two m2 to m4 is independently selected.

In equation (b-2),
R ^{1 to} R ⁴ are independently monovalent aliphatic groups or monovalent aromatic groups, respectively.
Z ¹ and Z ² are independently divalent aliphatic groups or divalent aromatic groups, respectively.
r is a positive integer.

Specific examples of the compound represented by the formula (b-1) include compounds represented by the following formulas (b-11) to (b-17).

Among the above compounds, the compound represented by the formula (b-11) is preferable, and the compound represented by the following formula (b-111), that is, 3,5-diaminobenzoic acid is more preferable.

The structural unit (B-1) is a structural unit that imparts a carboxyl group to the polyimide resin. When the polyimide resin has a carboxyl group, the polyimide resins can be crosslinked with each other via a cross-linking agent described later. When the structural unit B includes the structural unit (B-1), the chemical resistance of the film can be improved.

^{R 1} , R ² , R ³ and R ⁴ in the formula (b-2) independently represent a monovalent aliphatic group or a monovalent aromatic group, which may be substituted with a fluorine atom. .. Examples of the monovalent aliphatic group include a monovalent saturated hydrocarbon group and a monovalent unsaturated hydrocarbon group. Examples of the monovalent saturated hydrocarbon group include an alkyl group having 1 to 22 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. Examples of the monovalent unsaturated hydrocarbon group include an alkenyl group having 2 to 22 carbon atoms, and examples thereof include a vinyl group and a propenyl group. Examples of the monovalent aromatic group include an aryl group having 6 to 24 carbon atoms and an aralkyl group. As R ¹ , R ² , R ³ and R ⁴ , a methyl group or a phenyl group is particularly preferable.
Further, Z ¹ and Z ² independently represent a divalent aliphatic group or a divalent aromatic group, and these groups may be substituted with a fluorine atom or may contain an oxygen atom. .. When an oxygen atom is contained as an ether bond, the carbon number shown below means all the carbon numbers contained in the aliphatic group or the aromatic group. Examples of the divalent aliphatic group include a divalent saturated hydrocarbon group and a divalent unsaturated hydrocarbon group. Examples of the divalent saturated hydrocarbon group include an alkylene group having 1 to 22 carbon atoms, an alkyleneoxy group, and a saturated hydrocarbon group having an ether bond. Examples of the alkylene group include a methylene group, an ethylene group, and a propylene group. Examples of the alkyleneoxy group include a propyleneoxy group and a trimethyleneoxy group. Examples of the divalent unsaturated hydrocarbon group include an unsaturated carbon hydrogen group having 2 to 22 carbon atoms, and examples thereof include a vinylene group, a propenylene group, and an alkylene group having an unsaturated double bond at the terminal. Examples of the divalent aromatic group include a phenylene group having 6 to 24 carbon atoms, a phenylene group substituted with an alkyl group, and an aralkylene group. As Z ¹ and Z ² , a propylene group, a phenylene group, and an aralkylene group are particularly preferable.
Further, r represents a positive integer, and is preferably an integer of 10 to 10,000.

As described above, among the compounds represented by the formula (b-2), the compound represented by the following formula (b-21) is preferable.

（式（ｂ−２１）中、ｍ及びｎはそれぞれ独立に１以上の整数を示し、ｍとｎとの和は１０〜１０，０００の整数である。）

(In equation (b-21), m and n each independently represent an integer of 1 or more, and the sum of m and n is an integer of 10 to 10,000.)

The sum of m and n (m + n) is preferably 10 to 1,000, more preferably 10 to 500, more preferably 10 to 100, and even more preferably 10 to 50.
The ratio of m / n is preferably 5/95 to 50/50, more preferably 10/90 to 40/60, and even more preferably 20/80 to 30/70.

Examples of the compound represented by the formula (b-2) include 1,3-bis (3-aminopropyl) -1,1,2,2-tetramethyldisiloxane and 1,3-bis (3-aminobutyl). -1,1,2,2-tetramethyldisiloxane, bis (4-aminophenoxy) dimethylsilane, 1,3-bis (4-aminophenoxy) tetramethyldisiloxane, 1,1,3,3-tetramethyl -1,3-bis (4-aminophenyl) disiloxane, 1,1,3,3-tetraphenoxy-1,3-bis (2-aminoethyl) disiloxane, 1,1,3,3-tetraphenyl -1,3-bis (2-aminoethyl) disiloxane, 1,1,3,3-tetraphenyl-1,3-bis (3-aminopropyl) disiloxane, 1,1,3,3-tetramethyl -1,3-bis (2-aminoethyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis (3-aminopropyl) disiloxane, 1,1,3,3-tetramethyl -1,3-bis (4-aminobutyl) disiloxane, 1,3-dimethyl-1,3-dimethoxy-1,3-bis (4-aminobutyl) disiloxane, 1,1,3,3,5 , 5-Hexamethyl-1,5-bis (4-aminophenyl) trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis (4-aminobutyl) trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1, 5-bis (5-aminopentyl) trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis (2-aminoethyl) trisiloxane, 1,1,5,5 -Tetramethyl-3,3-dimethoxy-1,5-bis (4-aminobutyl) trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis (5-amino) Pentyl) trisiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis (3-aminopropyl) trisiloxane, 1,1,3,3,5,5-hexaethyl-1,5 Examples thereof include −bis (3-aminopropyl) trisiloxane, 1,1,3,3,5,5-hexapropyl-1,5-bis (3-aminopropyl) trisiloxane and the like. The above compounds may be used alone or in combination of two or more.
Commercially available products of the compound represented by the formula (b-2) include "X-22-9409", "X-22-1660B" and "X-22-161A" manufactured by Shin-Etsu Chemical Co., Ltd. , "X-22-161B" and the like.

When the structural unit B includes the structural unit (B-2), the colorless transparency and optical isotropic property of the film and the detergency of the polyimide resin composition can be improved.

The compound represented by the formula (b-3) is 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether.
When the structural unit B includes the structural unit (B-3), the optical isotropic property of the film and the storage stability and detergency of the polyimide resin composition can be improved.

The ratio of the structural unit (B-1) in the structural unit B is preferably 20 to 75 mol%, more preferably 25 to 70 mol%, and further preferably 30 to 60 mol%.
The ratio of the structural unit (B-2) in the structural unit B is preferably 1 to 25 mol%, more preferably 2 to 20 mol%, and further preferably 3 to 15 mol%.
The ratio of the structural unit (B-3) in the structural unit B is preferably 20 to 75 mol%, more preferably 25 to 70 mol%, and further preferably 30 to 60 mol%.
The total ratio of the constituent units (B-1) to (B-3) in the constituent unit B is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more. It is particularly preferably 99 mol% or more. The upper limit of the total ratio of the structural units (B-1) to (B-3) is not particularly limited, that is, 100 mol%. The structural unit B may be composed of only the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3).

The structural unit B may include a structural unit other than the structural units (B-1) to (B-3). The diamine that gives such a structural unit is not particularly limited, but is limited to 1,4-phenylenediamine, p-xylylene diamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine. , 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'- Diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-inden-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 Aromatic diamines such as-(4-aminophenoxy) phenyl] propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, and 9,9-bis (4-aminophenyl) fluorene. However, the compound represented by the formula (b-1), the compound represented by the formula (b-2), and the compound represented by the formula (b-3) are excluded); 1,3-bis (aminomethyl). ) Alicyclic diamines such as cyclohexane and 1,4-bis (aminomethyl) cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine (excluding compounds represented by the formula (b-2)). Be done.
In the present specification, the aromatic diamine means a diamine containing one or more aromatic rings, and the alicyclic diamine means a diamine containing one or more alicyclic rings and not containing an aromatic ring, and is a fat. The group diamine means a diamine that does not contain an aromatic ring or an alicyclic ring.
The structural unit arbitrarily included in the structural unit B (that is, the structural unit other than the structural units (B-1) to (B-3)) 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 obtained polyimide film. The number average molecular weight of the polyimide resin can be obtained from, for example, a standard polymethylmethacrylate (PMMA) conversion value measured by gel filtration chromatography.

<Manufacturing method of polyimide resin>
In the present invention, the polyimide resin includes a tetracarboxylic acid component containing the compound giving the above-mentioned structural unit (A-1), a compound giving the above-mentioned structural unit (B-1), and the above-mentioned structural unit (B-2). It can be produced by reacting with a compound which gives the above-mentioned structural unit (B-3) and a diamine component containing the compound which gives the above-mentioned structural unit (B-3).

Examples of the compound giving the structural unit (A-1) include, but are not limited to, the compound represented by the formula (a-1), and may be a derivative thereof as long as the same structural unit is given. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1) (that is, 1,2,4,5-cyclohexanetetracarboxylic acid), and the tetracarboxylic acid. Alkyl esters can be mentioned. As the compound giving the structural unit (A-1), the compound represented by the formula (a-1) (that is, dianhydride) is preferable.

The tetracarboxylic acid component preferably contains 50 mol% or more, more preferably 70 mol% or more, and further preferably 85 mol% or more of the compound giving the constituent unit (A-1). The upper limit of the content ratio 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 the compound giving the constituent unit (A-1).

The tetracarboxylic acid component may contain a compound other than the compound giving the structural unit (A-1), and examples of the compound include the above-mentioned aromatic tetracarboxylic acid dianhydride and alicyclic tetracarboxylic acid dianhydride. And aliphatic tetracarboxylic acid dianhydrides, and derivatives thereof (tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.).
The compound arbitrarily contained in the tetracarboxylic acid component (that is, the compound other than the compound giving the constituent unit (A-1)) may be one kind or two or more kinds.

As the compound arbitrarily contained in the tetracarboxylic acid component, a compound giving a structural unit (A-2) is preferable.
Examples of the compound giving the structural unit (A-2) include the compound represented by the formula (a-2), but the compound is not limited to this, and may be a derivative thereof as long as the same structural unit is given. 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), the compound represented by the formula (a-2) (that is, dianhydride) is preferable.

When the tetracarboxylic acid component contains a compound giving a structural unit (A-1) and a compound giving a structural unit (A-2), the tetracarboxylic acid component is a compound giving a structural unit (A-1), preferably 50. A compound containing ~ 99 mol%, more preferably 50 to 95 mol%, still more preferably 70 to 95 mol%, particularly preferably 85 to 95 mol%, and giving a constituent unit (A-2) is preferable. It contains 1 to 50 mol%, more preferably 5 to 50 mol%, still more preferably 5 to 30 mol%, and particularly preferably 5 to 15 mol%.
The tetracarboxylic acid component contains, in total, a compound giving the constituent unit (A-1) and a compound giving the constituent unit (A-2) in an amount of preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably. Contains 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the total content ratio of the compound giving the structural unit (A-1) and the compound giving the structural unit (A-2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist only of a compound that gives a constituent unit (A-1) and a compound that gives a constituent unit (A-2).

The compound giving the structural unit (B-1), the compound giving the structural unit (B-2), and the compound giving the structural unit (B-3) are the compound represented by the formula (b-1) and the formula, respectively. Examples thereof include the compound represented by (b-2) and the compound represented by the formula (b-3), but the present invention is not limited to these, and derivatives thereof may be used as long as the same structural unit is given. Examples of the derivative include diisocyanates corresponding to diamines represented by the formulas (b-1) to (b-3).
The compound that gives the structural unit (B-1), the compound that gives the structural unit (B-2), and the compound that gives the structural unit (B-3) are compounds represented by the formula (b-1) (that is, each of them). , Diamine), the compound represented by the formula (b-2) (ie, diamine), and the compound represented by the formula (b-3) (ie, diamine) are preferable.

The diamine component preferably contains the compound giving the structural unit (B-1) in an amount of 20 to 75 mol%, more preferably 25 to 70 mol%, still more preferably 30 to 60 mol%.
The diamine component preferably contains 1 to 25 mol%, more preferably 2 to 20 mol%, and further preferably 3 to 15 mol% of the compound giving the structural unit (B-2).
The diamine component preferably contains the compound giving the structural unit (B-3) in an amount of 20 to 75 mol%, more preferably 25 to 70 mol%, still more preferably 30 to 60 mol%.
The diamine component contains a compound that gives the structural unit (B-1), a compound that gives the structural unit (B-2), and a compound that gives the structural unit (B-3) in total, preferably 50 mol% or more, and more. It preferably contains 70 mol% or more, more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total content ratio of the compound giving the structural unit (B-1), the compound giving the structural unit (B-2), and the compound giving the structural unit (B-3) is not particularly limited, that is, 100. Mol%. The diamine component may consist only of a compound giving a structural unit (B-1), a compound giving a structural unit (B-2), and a compound giving a structural unit (B-3).

The diamine component may contain a compound other than the compound giving the structural unit (B-1), the compound giving the structural unit (B-2), and the compound giving the structural unit (B-3). Examples thereof include the above-mentioned aromatic diamines, alicyclic diamines, and aliphatic diamines, and derivatives thereof (diisocyanate and the like).
Compounds arbitrarily contained in the diamine component (that is, compounds other than the compound giving the structural unit (B-1), the compound giving the structural unit (B-2), and the compound giving the structural unit (B-3)) are It may be one kind or two or more kinds.

In the present invention, the ratio of the amount of the tetracarboxylic acid component to the diamine component charged in the production of the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component with respect to 1 mol of the tetracarboxylic acid component.

Further, in the present invention, in addition to the above-mentioned tetracarboxylic acid component and diamine component, an end-capping agent may be used for producing the polyimide resin. As the terminal encapsulant, monoamines or dicarboxylic acids are preferable. The amount of the terminal encapsulant to be introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. Examples of monoamine terminal sealants 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 terminal encapsulant, dicarboxylic acids are preferable, and a part thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic 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 preferably used.

The method for reacting the above-mentioned tetracarboxylic acid component with the diamine component is not particularly limited, and a known method can be used.
Specific reaction methods include (1) charging a tetracarboxylic acid component, a diamine component, and a reaction solvent into a reactor, stirring at room temperature (about 20 ° C.) to 80 ° C. for 0.5 to 30 hours, and then ascending. Method of warming to carry out imidization reaction, (2) After charging the diamine component and reaction solvent into the reactor and dissolving them, the tetracarboxylic acid component is charged and, if necessary, at room temperature (about 20 ° C.) to 80 ° C. A method of stirring for 0.5 to 30 hours and then raising the temperature to carry out the imidization reaction. (3) The tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into the reactor, and the temperature is immediately raised to carry out the imidization reaction. And the like.

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

Specific examples of the aprotonic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea and the like. Amide-based solvents, lactone-based solvents such as γ-butyrolactone and γ-valerolactone, phosphorus-containing amide-based solvents such as hexamethylphosphoric amide and hexamethylphosphintriamide, and sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide, and sulfolane. Examples thereof include based solvents, ketone solvents such as acetone, cyclohexanone and methylcyclohexanone, amine solvents such as picolin and pyridine, and ester solvents such as acetic acid (2-methoxy-1-methylethyl).

Specific examples of the phenolic 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 can be mentioned.
Specific examples of the ether solvent include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, and 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, an amide solvent or a lactone solvent is preferable. Moreover, the above-mentioned reaction solvent may be used alone or in mixture of 2 or more types.

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

In the above imidization reaction, a known imidization 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. Examples thereof include 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 hydrogencarbonate and sodium hydrogencarbonate.
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, paratoluenesulfonic acid, naphthalenesulfonic acid and the like. Can be mentioned. The above-mentioned imidization catalyst may be used alone or in combination of two or more.
Of the above, from the viewpoint of handleability, it is preferable to use a base catalyst, more preferably an organic base catalyst, further 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 cross-linking agent has at least two oxazolyl groups. That is, the cross-linking agent in the present invention is a polyfunctional oxazoline compound having two or more oxazoline groups (oxazoline rings) in the molecule.
The oxazolyl group has reactivity with the 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 easy 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 crosslinked with each other via a cross-linking agent to form a crosslinked polyimide resin. NS. For this reason, the chemical resistance of the film is improved.

The cross-linking agent is not particularly limited as long as it is a polyfunctional oxazoline compound having two or more oxazoline groups in the molecule, and specific examples thereof include 1,3-bis (4,5-dihydro-2-oxazoline) benzene. 1,4-Bis (4,5-dihydro-2-oxazoline) benzene, 2,2'-bis (2-oxazoline), K-2010E, K-2020E, K-2030E, 2, manufactured by Nippon Catalyst Co., Ltd. 6-bis (4-isopropyl-2-oxazoline-2-yl) pyridine, 2,6-bis (4-phenyl-2-oxazoline-2-yl) pyridine, 2,2'-isopropyridenebis (4-phenyl) -2-Oxazoline), 2,2'-isopropylidenebis (4-talshalbutyl-2-oxazoline) and the like.
The cross-linking agent is preferably a compound containing an aromatic ring or an aromatic heterocycle having at least two oxazolyl groups bonded thereto, more preferably a compound containing a benzene ring or a pyridine ring having at least two oxazolyl groups bonded thereto, and further. A compound containing a benzene ring in which at least two oxazolyl groups are bonded is preferable, and 1,3-bis (4,5-dihydro-2-oxazolyl) benzene is particularly preferable.
The cross-linking agent may be used alone or in combination of two or more.

In the polyimide resin composition of the present invention, the molar ratio (oxazolyl group / carboxyl group) of the oxazolyl group in the cross-linking agent to the carboxyl group in the polyimide resin is in the range of 1/4 to 1 / 0.5. Therefore, it is preferable to contain a polyimide resin and a cross-linking agent. The molar ratio is more preferably 1/4 to 1/1, still more preferably 1/2 to 1/1, even more preferably 1/2 to 1 / 1.5, and even more preferably. Is 1/2 to 1 / 1.7.
The above molar ratio means the molar ratio of the oxazolyl group contained in the cross-linking agent to the carboxyl group contained in the compound giving the structural unit (B-1) used for producing the polyimide resin, and the addition of the cross-linking agent. Calculated based on the amount and amount of compound added to give the building block (B-1).

Further, the polyimide resin composition of the present invention contains an inorganic filler, an adhesion accelerator, a release agent, a flame retardant, an ultraviolet stabilizer, a surfactant, a leveling agent, a defoaming agent, as long as the required properties of the polyimide film are not impaired. Various additives such as a fluorescent whitening agent, a cross-linking agent, a polymerization initiator, and a photosensitizer may be contained.
The method for producing the polyimide resin composition of the present invention is not particularly limited, and a known method can be applied.

The polyimide resin composition of the present invention can form a film having excellent colorless transparency, optical isotropic properties, and chemical resistance. Suitable physical property values of the film that can be formed by using the polyimide resin composition of the present invention are as follows.
The total light transmittance is preferably 88% or more, more preferably 90% or more, still more preferably 91% or more when the film has a thickness of 10 μm.
The yellow index (YI) is preferably 2.5 or less, more preferably 2.3 or less, and further preferably 2.0 or less when the film has a thickness of 10 μm.
b ^* is preferably 1.5 or less, more preferably 1.2 or less, and further preferably 1.0 or less when the film has a thickness of 10 μm.
The haze is preferably 2.0% or less, more preferably 1.0% or less, and further preferably 0.6% or less when the film has a thickness of 10 μm.
The absolute value of the thickness retardation (Rth) is preferably 100 nm or less, more preferably 90 nm or less, and further preferably 60 nm or less when the film has a thickness of 10 μm.
The mixed acid ΔYI is preferably 1.5 or less, more preferably 1.3 or less, and further preferably 1.2 or less when the film has a thickness of 10 μm.
The mixed acid ΔYI means the difference in YI before and after the immersion of the polyimide film in the mixture of phosphoric acid, nitric acid and acetic acid, respectively, and specifically, it shall be measured by the method described in Examples. Can be done. The smaller ΔYI, the better the acid resistance. By using the polyimide resin composition of the present invention, a film having excellent chemical resistance can be formed, and it also exhibits excellent resistance to acids. In particular, a mixed solution of 50 to 97% by mass of phosphoric acid, 1 to 20% by mass of nitrate, 1 to 10% by mass of acetic acid, and 1 to 20% by mass of water, preferably 63 to 87% by mass of phosphoric acid. It shows excellent resistance to a mixed solution of 5 to 15% by mass of mass%, 5 to 15% by mass of nitrate, 3 to 7% by mass of acetic acid, and 5 to 15% by mass of water.

The film that can be formed using the polyimide resin composition of the present invention has good mechanical properties and heat resistance, and has the following suitable physical property values.
The tensile elastic modulus is preferably 2.0 GPa or more, more preferably 2.5 GPa or more, and further preferably 2.7 GPa or more.
The tensile strength is preferably 60 MPa or more, more preferably 70 MPa or more, and further preferably 80 MPa or more.
The tensile elongation at break is preferably 5.0% or more, more preferably 6.0% or more, and further preferably 7.5% or more.
The glass transition temperature (Tg) is preferably 230 ° C. or higher, more preferably 250 ° C. or higher, and even more preferably 290 ° C. or higher.
The above-mentioned physical property values in the present invention can be specifically measured by the method described in Examples.

[Polyimide varnish]
As a preferred embodiment of the polyimide resin composition of the present invention, a polyimide resin composition containing an organic solvent in addition to the above-mentioned polyimide resin and the above-mentioned cross-linking agent, and the polyimide resin is dissolved in the organic solvent ( Hereinafter, it is also referred to as "polyimide varnish").
That is, the polyimide varnish of the present invention contains a polyimide resin composition and an organic solvent.

The organic solvent may be any one that dissolves the polyimide resin, and is not particularly limited, but it is preferable to use the above-mentioned compounds alone or in combination of two or more as the reaction solvent used for producing the polyimide resin.
Examples of the organic solvent include an aprotic solvent, a phenol solvent, an ether solvent, a carbonate solvent and the like.

Specific examples of the aprotonic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea and the like. Amide-based solvents, lactone-based solvents such as γ-butyrolactone and γ-valerolactone, phosphorus-containing amide-based solvents such as hexamethylphosphoric amide and hexamethylphosphintriamide, and sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide, and sulfolane. Examples thereof include based solvents, ketone solvents such as acetone, cyclohexanone and methylcyclohexanone, amine solvents such as picolin and pyridine, and ester solvents such as acetic acid (2-methoxy-1-methylethyl).

Specific examples of the phenolic 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 can be mentioned.
Specific examples of the ether solvent include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, and 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 organic solvents, an amide solvent or a lactone solvent is preferable, and a lactone solvent is more preferable from the viewpoint of detergency. Among the lactone-based solvents, γ-butyrolactone and γ-valerolactone are preferable, and γ-butyrolactone is more preferable.

When a lactone-based solvent is used as the organic solvent, the ratio of the lactone-based solvent in the organic solvent contained in the polyimide varnish is preferably 70 to 100% by mass, more preferably 80 to 100% by mass or more, and further 90 to 100% by mass. Preferably, it may consist only of a lactone-based solvent.
Since the lactone-based solvent has a low hygroscopicity, the varnish does not absorb moisture in the environment when the film is applied, and whitening due to the precipitation of polyimide and roughening of the film surface surface are unlikely to occur, which is preferable. In addition, it is preferable because the processability can be improved, such as eliminating the need to control the humidity in the environment.
The above-mentioned organic solvent may be used alone or in combination of two or more.

The polyimide varnish may be a solution in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, to which a cross-linking agent is added, or a solution in which a diluting solvent and a cross-linking agent are added. It may be.

The above-mentioned polyimide resin has solvent solubility, and the cross-linking reaction with the cross-linking agent hardly proceeds at room temperature. Therefore, a polyimide varnish that is stable at room temperature can be obtained. The polyimide varnish preferably contains 1 to 40% by mass of the polyimide resin, and more preferably 2 to 40% by mass.
Among them, it is more preferably contained in an amount of 5 to 40% by mass, further preferably contained in an amount of 10 to 30% by mass, and further preferably contained in an amount of 15 to 25% by mass, because it can be stored in a stable and high concentration and the film formation is good. Even more preferable. The viscosity of the polyimide varnish is preferably 1 to 200 Pa · s, more preferably 2 to 100 Pa · s. The viscosity of the polyimide varnish is a value measured at 25 ° C. using an E-type viscometer.

Further, when applying the film, it is preferable to lower the concentration of the polyimide resin in the polyimide varnish, and it is also preferable to dilute it with the organic solvent. From the viewpoint of improving the detergency of the apparatus, the polyimide varnish used at the time of film coating preferably contains 1 to 10% by mass of the polyimide resin, more preferably 2 to 8% by mass, and 4 to 7% by mass. Is even more preferable. The viscosity at that time is preferably 0.1 to 15 Pa · s, more preferably 1 to 10 Pa · s, and even more preferably 2 to 5 Pa · s. By setting the polyimide resin concentration or viscosity within such a range, the varnish inside the apparatus used for film coating with the cleaning liquid can be easily replaced and the cleaning property is improved.

[Polyimide film]
The polyimide film of the present invention is obtained by cross-linking the above-mentioned polyimide resin contained in the polyimide resin composition of the present invention with the above-mentioned cross-linking agent. That is, the polyimide film of the present invention contains a crosslinked polyimide resin which is a crosslinked product between polyimide resins via a crosslinking agent. Therefore, the polyimide film of the present invention is excellent in colorless transparency, optical isotropic property, and chemical resistance. Suitable physical property values of the polyimide film of the present invention are as described above.
In the method for producing a polyimide film of the present invention, a step of heating at a temperature at which the cross-linking reaction between the polyimide resin and the cross-linking agent proceeds (preferably 80 ° C. or higher, more preferably 100 ° C. or higher, still more preferably 150 ° C. or higher) is performed. If included, there are no particular restrictions. For example, a method in which the above-mentioned polyimide varnish is applied onto 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, it is possible to remove organic solvents such as a reaction solvent and a diluting solvent contained in the polyimide varnish while advancing the cross-linking reaction between the polyimide resin in the polyimide varnish and the cross-linking agent.

Examples of the coating method include known coating methods such as spin coating, slit coating, and blade coating.
As the heat treatment, the organic solvent is evaporated at a temperature of 60 to 150 ° C. to make it tack-free, and then dried at a temperature equal to or higher than the boiling point of the organic solvent used (preferably 200 to 500 ° C.). preferable. Further, it is preferable to dry in an air atmosphere or a nitrogen atmosphere. The pressure in the dry atmosphere may be reduced pressure, normal pressure, or pressurized.
The method of peeling the polyimide film formed on the support from the support is not particularly limited, but a laser lift-off method or a method of using a sacrificial layer for peeling (a mold release agent is applied to the surface of the support in advance). How to put) can be mentioned.

The thickness of the polyimide film of the present invention can be appropriately selected depending on the intended use, but is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, and further preferably 10 to 80 μm. When the thickness is 1 to 250 μm, it can be practically used as a self-supporting film.
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 color filters, flexible displays, semiconductor parts, and optical members. The polyimide film of the present invention is particularly preferably used as a substrate for an image display device such as a liquid crystal display or an OLED display.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to these examples.

In Examples and Comparative Examples, each physical property was measured by the method shown below.
(1) Solid content concentration To measure the solid content concentration of the polyimide resin solution and the polyimide varnish, the sample is heated at 320 ° C. × 120 min in a small electric furnace “MMF-1” manufactured by AS ONE 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 Co., Ltd.
(3) Tensile strength, tensile elastic modulus, tensile elongation at break Tensile strength, tensile elastic modulus, and tensile modulus at break are in accordance with JIS K7127: 1999, and the tensile tester "Strograph VG-" manufactured by Toyo Seiki Co., Ltd. 1E ”was used for measurement. The distance between the chucks was 50 mm, the size of the test piece was 10 mm × 70 mm, and the test speed was 20 mm / min.
(4) Glass transition temperature (Tg)
Using the thermomechanical analyzer "TMA / SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., residual stress is removed under the conditions of sample size 2 mm x 20 mm, load 0.1 N, and heating rate 10 ° C / min in tensile mode. The temperature was raised to a sufficient temperature to remove residual stress, and then cooled to room temperature. Then, the measurement of the elongation of the test piece was carried out under the same conditions as the treatment for removing the residual stress, and the place where the inflection point of the elongation was observed was determined as the glass transition temperature.
(5) Total light transmittance, yellow index (YI), b ^* , haze Total light transmittance, YI, b ^* , and haze conform to JIS K7105: 1981, and are colored and turbid by Nippon Denshoku Industries Co., Ltd. The measurement was performed using a simultaneous measuring device "COH400".
(6) Thickness phase difference (Rth)
The thickness phase difference (Rth) was measured using an ellipsometer "M-220" manufactured by JASCO Corporation. The value of the thickness phase difference at the measurement wavelength of 590 nm was measured. Rth is expressed by the following formula when the maximum in-plane refractive index of the polyimide film is nx, the minimum is ny, the refractive index in the thickness direction is nz, and the thickness of the film is d. It is a thing.
Rth = [{(nx + ny) / 2} -nz] × d
(7) Solvent resistance A solvent was dropped onto a polyimide film formed on a glass plate at room temperature, and it was confirmed whether or not there was any change in the film surface. As the solvent, propylene glycol monomethyl ether acetate (PGMEA) was used.
The evaluation criteria for solvent resistance were as follows.
A: There was no change on the film surface.
B: The film surface was slightly cracked.
C: The film surface was cracked or the film surface was melted.
(8) Acid resistance (mixed acid ΔYI)
_{A mixed acid (H 3} PO ₄ (70% by mass) + HNO ₃ (10% by mass) + CH ₃ COOH (5% by mass) + H ₂ O (15% by mass)) obtained by warming a polyimide film formed on a glass plate to 40 ° C. The mixture was immersed in a mixed solution for 4 minutes and then washed with water. After washing with water, the water was wiped off, and the mixture was heated on a hot plate at 240 ° C. for 50 minutes to dry. YI was measured before and after the test, and the change (ΔYI) was determined. The YI measurement here was performed in a state where a polyimide film was formed on a glass plate (a state of a glass plate + a polyimide film).
(9) Storage stability The polyimide varnish was stored at room temperature (23 ° C.) for 1 week, and it was visually confirmed whether or not Haze appeared in the varnish. After storage for one week, the one without Haze was evaluated as A, and the one with Haze was evaluated as C. Specifically, (5) those having less than 5% by the same evaluation method as haze are A as those without haze, and (5) those having 5% or more by the same evaluation method as haze. It was designated as C as Haze appeared.
(10) Detergency A PGME / PGMEA mixed solution is obtained by mixing propylene glycol monomethyl ether (PGME) and propylene glycol monomethyl ether acetate (PGMEA) so that the mass ratio of PGME / PGMEA is 7/3. Was prepared. The polyimide varnish was mixed with the PGME / PGMEA mixture, and it was confirmed whether or not the mixture was uniformly mixed at room temperature. If the mixture is not uniformly mixed, precipitates are generated and the mixed solution becomes cloudy. Therefore, the detergency was evaluated by measuring the haze of the mixed solution by the same evaluation method as in (5) Haze.
The evaluation criteria for detergency were as follows.
A: Polyimide varnish and PGME / PGMEA mixture were uniformly mixed. Haze was 1% or less.
C: The polyimide varnish and the PGME / PGMEA mixture were not uniformly mixed, and a precipitate was formed. Haze was greater than 1%.

The abbreviations for the tetracarboxylic acid component, diamine component, and cross-linking agent used in Examples and Comparative Examples are as follows.
<Tetracarboxylic acid component>
HPMDA: 1,2,4,5-Cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (a-1))
6FDA: 4,4'-(hexafluoroisopropyridene) diphthalic anhydride (manufactured by Daikin Industries, Ltd .; compound represented by formula (a-2))
<Diamine component>
3,5-DABA: 3,5-diaminobenzoic acid (manufactured by Nippon Pure Chemical Industries, Ltd .; compound represented by formula (b-1))
X-22-9409: Bi-terminal amino-modified silicone oil "X-22-9409" (manufactured by Shin-Etsu Chemical Co., Ltd .; compound represented by formula (b-2))
6FODA: 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether (manufactured by ChinaTech Chemical (Tianjin) Co., Ltd; compound represented by formula (b-3))
HFBAPP: 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane (manufactured by Seika Co., Ltd.)
TFMB: 2,2'-bis (trifluoromethyl) benzidine (manufactured by Seika Co., Ltd.)
<Crosslinking agent>
1,3-PBO: 1,3-bis (4,5-dihydro-2-oxazolyl) benzene (manufactured by Mikuni Pharmaceutical Co., Ltd.)

<Example 1>
8.518g (0) of 3,5-DABA in a 1L 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. .056 mol), 13.709 g (0.010 mol) of X-22-9409, 18.833 g (0.056 mol) of 6FODA, and 66.873 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation). The mixture was charged and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 27.333 g (0.122 mol) of HPMDA and 16.718 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) Was added and heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 172.409 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (1) was obtained.
Subsequently, 3.784 g (0.0175 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (1), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.6% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

<Example 2>
8.173g (0) of 3,5-DABA in a 1L 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. .054 mol), 13.155 g (0.010 mol) of X-22-9409, 18.071 g (0.054 mol) of 6FODA, and 66.699 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation). The mixture was charged and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 23.605 g (0.105 mol) of HPMDA and 8.338 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and after stirring for 10 minutes, 6 FDA was added to 5. After adding .211 g (0.012 mol) and 8.338 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) in a batch, 0.617 g of triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. , The temperature inside the reaction system was raised to 190 ° C. over about 20 minutes by heating with a mantle heater. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 172.626 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize, and the solid content concentration was 20.0 mass. % Polyimide resin solution (2) was obtained.
Subsequently, 3.655 g (0.0169 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (2), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.6% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

<Comparative example 1>
28.625g (0) of 3,5-DABA in a 1L 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. .188 mol) and 84.928 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 42.149 g (0.188 mol) of HPMDA and 21.232 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) Was added and heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 149.840 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (3) was obtained.
Subsequently, 12.704 g (0.059 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (3), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.6% by mass was obtained. After that, when the polyimide varnish was allowed to stand at room temperature, white precipitates were formed in the polyimide varnish, and the fluidity of the polyimide varnish was lost. Therefore, it was difficult to make a film. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.

<Comparative example 2>
41.034 g (0.122 mol) of 6FODA in a 1 L 5-necked round-bottom flask equipped with a stainless steel half-moon agitator, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. Then, 82.073 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 27.361 g (0.122 mol) of HPMDA and 20.518 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) Was added and heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 153.408 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (4) was obtained.
No cross-linking agent 1,3-PBO was added to this polyimide resin solution (4), and the polyimide varnish was used as it was. That is, the obtained polyimide varnish (polyimide resin solution (4)) was applied onto a glass plate by spin coating, held at 80 ° C. for 20 minutes on a hot plate, and then kept at 260 ° C. in a hot air dryer under an air atmosphere. The solvent was evaporated by heating in 30 minutes to obtain a film. The results are shown in Table 1.

<Comparative example 3>
24.160 g (0.075 mol) of TFMB in a 1 L 5-necked round-bottom flask equipped with a stainless steel half-moon agitator, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. 11.478 g (0.075 mol) of 3,5-DABA and 83.318 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the temperature inside the system was 70 ° C., in a nitrogen atmosphere, and the rotation speed was 200 rpm. The mixture was stirred to obtain a solution.
To this solution, 33.794 g (0.151 mol) of HPMDA and 20.830 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) Was added and heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 151.852 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (5) was obtained.
Subsequently, 5.069 g (0.023 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (5), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.5% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the addition amount of 1,3-PBO and the addition amount of 3,5-DABA is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

<Comparative example 4>
24.894 g (0.074 mol) of 6FODA in a 1 L 5-necked round-bottom flask equipped with a stainless steel half-moon agitator, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. 11.266 g (0.074 mol) of 3,5-DABA and 83.198 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the temperature inside the system was 70 ° C., in a nitrogen atmosphere, and the rotation speed was 200 rpm. The mixture was stirred to obtain a solution.
To this solution, 33.172 g (0.148 mol) of HPMDA and 20.800 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) Was added and heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 152.002 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (6) was obtained.
Subsequently, 5.000 g (0.023 mol) of 1,3-PBO as a cross-linking agent is added to 200 g of the polyimide resin solution (6), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin are contained. A polyimide varnish having a solid content concentration of 19.5% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

<Comparative example 5>
6.994 g (0) of 3,5-DABA in a 1 L 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. .046 mol), 13.688 g (0.010 mol) of X-22-9409, 23.951 g (0.046 mol) of HFBAPP, and 65.994 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation). The mixture was charged and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 22.861 g (0.102 mol) of HPMDA and 16.498 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) And 0.057 g of tetraethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were added and heated with a mantle heater to raise the temperature inside the reaction system to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 173.51 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (7) was obtained.
Subsequently, 3.784 g (0.0175 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (7), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.6% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

<Comparative Example 6>
8.640g (0) of 3,5-DABA in a 1L 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. .057 mol), 13.906 g (0.010 mol) of X-22-9409, 18.861 g (0.056 mol) of TFMB, and 66.934 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation). The mixture was charged and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 27.724 g (0.124 mol) of HPMDA and 16.734 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and then triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. ) Was added and heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 172.332 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (8) was obtained.
Subsequently, 3.853 g (0.0178 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (8), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.6% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

<Comparative Example 7>
8.183g (0) of 3,5-DABA in a 1L 5-necked round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. .054 mol), 13.859 g (0.010 mol) of X-22-9409, 17.224 g (0.054 mol) of TFMB, and 66.721 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation). The mixture was charged and stirred at a system temperature of 70 ° C. and a nitrogen atmosphere at a rotation speed of 200 rpm to obtain a solution.
To this solution, 23.733 g (0.106 mol) of HPMDA and 8.340 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch, and after stirring for 10 minutes, 6 FDA was added to 5. After adding 239 g (0.012 mol) and 8.340 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) in a batch, 0.595 g of triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst. , The temperature inside the reaction system was raised to 190 ° C. over about 20 minutes by heating with a mantle heater. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. while adjusting the rotation speed according to the increase in viscosity, and the mixture was refluxed for about 5 hours.
Then, 172.598 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to cool the temperature inside the reaction system to 120 ° C., and then the mixture was further stirred for about 3 hours to homogenize the solid content concentration of 20% by mass. A polyimide resin solution (9) was obtained.
Subsequently, 3.650 g (0.0169 mol) of 1,3-PBO as a cross-linking agent was added to 200 g of the polyimide resin solution (9), and after stirring at room temperature for 1 hour, the cross-linking agent and the polyimide resin were contained. A polyimide varnish having a solid content concentration of 19.6% by mass was obtained. The molar ratio of oxazolyl group / carboxyl group calculated based on the amount of 1,3-PBO added and the amount of 3,5-DABA added is 1/2.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to remove the solvent. Evaporation gave a film. The results are shown in Table 1.

As shown in Table 1, the polyimide films of Examples 1 and 2 are all excellent in colorless transparency, optical isotropic property, and chemical resistance (solvent resistance and acid resistance), and are excellent in Example 1. The polyimide varnishes of and 2 were excellent in storage stability and detergency.
On the other hand, in Comparative Example 1, a polyimide varnish was obtained by adding a cross-linking agent to a polyimide resin solution and stirring for 1 hour. After that, when the polyimide varnish was allowed to stand at room temperature, white precipitates were formed in the polyimide varnish. The fluidity of the polyimide varnish was lost. That is, the polyimide varnish of Comparative Example 1 was inferior in storage stability and detergency.
The polyimide film of Comparative Example 2 was inferior in solvent resistance. In addition, the mixed acid ΔYI value was as large as 1.57, and the acid resistance was also inferior.
The polyimide film of Comparative Example 3 was inferior in optical isotropic properties. Further, the polyimide varnish of Comparative Example 3 was inferior in detergency.
The polyimide varnish of Comparative Example 4 was inferior in detergency.
The polyimide film of Comparative Example 5 did not have good solvent resistance. Further, the polyimide varnish of Comparative Example 5 was inferior in detergency.
The polyimide varnish of Comparative Example 6 was inferior in storage stability and detergency.
The polyimide varnish of Comparative Example 7 was inferior in detergency.

Claims (11)

A polyimide resin composition containing a polyimide resin and a cross-linking 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 includes a structural unit (A-1) derived from a compound represented by the following formula (a-1).
The structural unit B is 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 the structural unit (B-3) derived from the compound represented by the following formula (b-3).

(In equation (b-1),
X is a single bond, substituted or unsubstituted alkylene group, carbonyl group, ether group, a group represented by the following formula (b-1-i), or a group represented by the following formula (b-1-ii). can be,
p is an integer from 0 to 2
m1 is an integer from 0 to 4,
m2 is an integer from 0 to 4.

[In the formula (b-1-i), m3 is an integer of 0 to 5, and in the formula (b-1-ii), m4 is an integer of 0 to 5. ]
However,
m1 + m2 + m3 + m4 is 1 or more,
When p is 0, m1 is an integer of 1 to 4.
When p is 2, each of the two Xs and the two m2 to m4 is independently selected;
In equation (b-2),
R ^{1 to} R ⁴ are independently monovalent aliphatic groups or monovalent aromatic groups, respectively.
Z ¹ and Z ² are independently divalent aliphatic groups or divalent aromatic groups, respectively.
r is a positive integer. ) The polyimide resin composition according to claim 1, wherein the structural unit (B-1) is a structural unit (B-11) derived from a compound represented by the following formula (b-11).

The polyimide resin composition according to claim 1 or 2, wherein the cross-linking agent is a compound containing an aromatic ring or an aromatic heterocycle having at least two oxazolyl groups bonded thereto. The polyimide resin composition according to claim 3, wherein the cross-linking agent is a compound containing a benzene ring having at least two oxazolyl groups bonded thereto. The polyimide resin composition according to claim 4, wherein the cross-linking agent is 1,3-bis (4,5-dihydro-2-oxazolyl) benzene. The polyimide resin composition according to any one of claims 1 to 5, wherein the ratio of the structural unit (A-1) in the structural unit A is 50 mol% or more. The ratio of the constituent unit (B-1) in the constituent unit B is 20 to 75 mol%.
The ratio of the constituent unit (B-2) in the constituent unit B is 1 to 25 mol%.
The polyimide resin composition according to any one of claims 1 to 6, wherein the ratio of the structural unit (B-3) in the structural unit B is 20 to 75 mol%. The polyimide resin composition according to any one of claims 1 to 7, wherein the structural unit A further contains a structural unit (A-2) derived from a compound represented by the following formula (a-2).

The ratio of the constituent unit (A-1) in the constituent unit A is 50 to 99 mol%.
The polyimide resin composition according to claim 8, wherein the ratio of the structural unit (A-2) in the structural unit A is 1 to 50 mol%. A polyamide varnish containing the polyimide resin composition according to any one of claims 1 to 9 and an organic solvent. A polyimide film obtained by cross-linking the polyimide resin in the polyimide resin composition according to any one of claims 1 to 9 with the cross-linking agent.