JP2009263654A - Polyimide, polyimide film, and methods for producing the same - Google Patents

Abstract

Even when an aliphatic tetracarboxylic dianhydride is used, it can be imidized with high reactivity, non-coloring property, low water absorption, transparency, moldability (specifically, Provided is a polyimide production method capable of giving a film excellent in ease of forming into a film and a small process load.
The method for producing a polyimide of the present invention comprises (A) reacting at least one acyl compound selected from aliphatic tetracarboxylic dianhydrides and their reactive derivatives with (B) an aromatic diamine. The polyamic acid thus obtained is imidized in the presence of an alicyclic tertiary monoamine. The method for producing a polyimide film of the present invention includes a step of applying a solution containing the obtained polyimide and an organic solvent on a substrate to form a coating film, and removing the organic solvent from the coating film by evaporation. Obtaining a film.
[Selection figure] None

Description

  The present invention relates to a polyimide, a film (polyimide film) produced using the polyimide, and a method for producing them.

Generally, wholly aromatic polyimides obtained from aromatic tetracarboxylic dianhydrides and aromatic diamines are due to the rigidity of the molecules, the fact that the molecules are resonance-stabilized, and the presence of strong chemical bonds. Has excellent heat resistance, mechanical properties, electrical properties, oxidation resistance and hydrolysis resistance. Films, coating agents, molded parts, insulating materials, etc. in fields such as electricity, batteries, automobiles and aerospace industries As widely used as.
On the other hand, in addition to excellent heat resistance, mechanical properties, etc., materials used for optical members need to be excellent in colorless transparency, easy moldability (molding) properties, optical properties (high refractive index, etc.) Is done.
Here, for example, wholly aromatic polyimide films represented by Kapton (manufactured by Toray DuPont) have excellent heat resistance as described above, and are suitable for the field of electricity, etc., but have high colorability. Moreover, since the moldability is low, there is a problem that the use as an optical material is limited.
That is, the film has a problem that it is colored from yellow to brown due to absorption in the visible light region derived from intermolecular or intramolecular charge transfer interaction. In addition, the film has a problem that the process load is high and the moldability is low, for example, heat treatment at a high temperature is required to form the film. Specifically, the polyimide forming the film has low solubility in an organic solvent, and the film cannot be formed using the polyimide as it is. Therefore, a polyamic acid solution, which is a precursor of polyimide, is used to form a film-like coating film by coating on a substrate, and then the coating film is heat-treated at a high temperature of about 400 ° C. It is necessary to imidize the acid to obtain a film made of polyimide.
In order to solve such problems, various types of polyimides have been proposed in which non-coloring properties and transparency are improved, and solubility in an organic solvent is imparted to improve moldability.
For example, as polyimide having improved transparency, cyclobutanetetracarboxylic dianhydride, aliphatic (alicyclic) tetracarboxylic dianhydride such as 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and the like A polyimide obtained from an aromatic diamine such as 4,4′-diaminodiphenyl ether has been proposed (Non-patent Document 1).

High Performance Polymer 19, P175-193 (2007)

The polyimide described in Non-Patent Document 1 is a semi-aromatic polyimide. In general, semi-aromatic polyimide is more transparent than aromatic polyimide. However, a polyamic acid synthesized using tetracarboxylic dianhydride has a problem that imidization hardly proceeds. In this case, the water absorption of the resin may increase or the durability may be insufficient.
Here, the use of an imidization catalyst has been proposed as a means for promoting imidization of polyamic acid. For example, pyridine and triethylamine are known as amine-based catalysts. As dehydration catalysts, acetic anhydride and trifluoroacetic anhydride are known. In order to sufficiently imidize polyamic acid obtained by reacting aliphatic tetracarboxylic dianhydride and aromatic diamine using these catalysts, the amount of catalyst is increased or the reaction temperature is set high. It is necessary to set reaction conditions such as extending the reaction time. However, when such reaction conditions are set, in addition to high costs, there is a problem that a side reaction accompanied by coloring is caused and the transparency of the resin is impaired.
Furthermore, although the polyimide described in Non-Patent Document 1 has improved transparency as compared with conventional polyimides, it is still insufficient in transparency for use as an optical material, and is soluble in organic solvents. Therefore, heat treatment (thermal imidation) at a high temperature using a polyamic acid as a precursor is required to form a film. Thus, the subject that a process load is large and a moldability is bad still remains.

  The present invention has been made in view of the above-mentioned problems, and even when an aliphatic tetracarboxylic dianhydride is used, it can be imidized with high reactivity, non-coloring property, and low water absorption. , Transparency, moldability (specifically, ease of forming into a film and low process load) polyimide that can give a film, polyimide film produced using the polyimide, And it aims at providing those manufacturing methods.

  As a result of intensive studies to achieve the above object, the present inventor reacted at least one acyl compound selected from aliphatic tetracarboxylic dianhydrides and their reactive derivatives with an aromatic diamine. It was found that the above-mentioned object of the present invention can be achieved by imidizing the polyamic acid obtained by using an alicyclic tertiary monoamine as an imidization catalyst, thereby completing the present invention.

（式（７）中、Ｒは、炭素数１〜４のアルキル基、Ｘは酸素原子又は硫黄原子、ｌは０又は１、ｍ及びｎは、各々独立して、０〜２の整数である。）
［３］ 上記（Ａ）成分が、５員環及び／又は６員環の酸無水物骨格を有する脂肪族テトラカルボン酸二無水物である上記［１］又は［２］に記載のポリイミドの製造方法。
［４］ さらに、無水酢酸、無水プロピオン酸、無水安息香酸のいずれかの酸無水物、これらの酸無水物に相当する酸クロライド類、及びカルボジイミド化合物からなる群より選ばれる少なくとも１種の脱水剤を用いる上記［１］〜［３］のいずれか１つに記載のポリイミドの製造方法。
［５］ 上記［１］〜［４］のいずれか１つに記載の方法で得られたポリイミド及び有機溶媒を含む溶液を基板上に塗布して塗膜を形成する工程と、該塗膜から前記有機溶媒を蒸発除去させることにより除去してフィルムを得る工程とを含む、ポリイミドフィルムの製造方法。
［６］ （Ａ）（ａ−１）５員環の酸無水物骨格を有し、かつ６員環の酸無水物骨格及び架橋環構造を有しない化合物、及び／又は、これらの反応性誘導体であるアシル化合物と（Ｂ）芳香族ジアミンとを反応させて得られるポリイミドであって、イミド化率が９５％以上であり、かつ、厚み２０μｍのフィルムを形成した際のＪＩＳ Ｋ７１０５透明度試験法に準じて測定したイエローインデックスが１．５以下であることを特徴とするポリイミド。
［７］ （Ａ）下記（ａ−２）成分、（ｂ）成分、及び（ｃ）成分からなる群より選ばれる少なくとも一種のアシル化合物と（Ｂ）芳香族ジアミンとを反応させて得られるポリイミドであって、イミド化率が８５％以上であり、かつ、厚み２０μｍのフィルムを形成した際のＪＩＳ Ｋ７１０５透明度試験法に準じて測定したイエローインデックスが１．５以下であることを特徴とするポリイミド。
（ａ−２）５員環の酸無水物骨格及び架橋環構造を有し、かつ、該架橋環構造を構成する少なくとも２つの炭素原子が酸無水物骨格を形成し、６員環の酸無水物骨格を有しない化合物、及びこれらの反応性誘導体
（ｂ）６員環の酸無水物骨格を有し、かつ、５員環の酸無水物骨格を有しない化合物、及びこれらの反応性誘導体
（ｃ）５員環の酸無水物骨格及び６員環の酸無水物骨格を有する化合物、及びこれらの反応性誘導体
［８］ イミド化率が１００％であると仮定した場合に、イミド基濃度が２．５〜５．５ｍｍｏｌ／ｇとなる上記［６］又は［７］に記載のポリイミド。
［９］ ポリスチレン換算の重量平均分子量が５０，０００〜１,０００，０００である上記［６］〜［８］のいずれかに記載のポリイミド。
［１０］ ２５℃で２４時間浸漬した場合の吸水率が、５質量％未満である上記［６］〜［９］のいずれかに記載のポリイミド。
［１１］ 上記［６］〜［１０］のいずれかに記載のポリイミド、及び有機溶媒を含有するポリイミド系樹脂組成物。
［１２］ 上記［６］〜［１０］のいずれかに記載のポリイミドからなるポリイミドフィルム。
［１３］ 光学部材用である上記［１２］に記載のフィルム。
［１４］ プリント配線用基板用である上記［１２］に記載のフィルム。 That is, the present invention provides the following [1] to [14].
[1] A polyamic acid obtained by reacting (A) at least one acyl compound selected from an aliphatic tetracarboxylic dianhydride and a reactive derivative thereof and (B) an aromatic diamine is used as an alicyclic group. A method for producing polyimide, comprising imidization in the presence of a secondary monoamine.
[2] The method for producing a polyimide according to [1], wherein the alicyclic tertiary monoamine is a compound represented by the following formula (7).

(In the formula (7), R is an alkyl group having 1 to 4 carbon atoms, X is an oxygen atom or sulfur atom, l is 0 or 1, and m and n are each independently an integer of 0 to 2. .)
[3] Production of polyimide according to [1] or [2], wherein the component (A) is an aliphatic tetracarboxylic dianhydride having a 5-membered ring and / or 6-membered acid anhydride skeleton. Method.
[4] Furthermore, at least one dehydrating agent selected from the group consisting of acetic anhydride, propionic anhydride, benzoic anhydride, acid chlorides corresponding to these anhydrides, and carbodiimide compounds The method for producing a polyimide according to any one of the above [1] to [3], wherein
[5] A step of applying a solution containing the polyimide and organic solvent obtained by the method according to any one of [1] to [4] on a substrate to form a coating film, and from the coating film And a step of removing the organic solvent by evaporating to obtain a film.
[6] (A) (a-1) A compound having a 5-membered ring acid anhydride skeleton and not having a 6-membered ring acid anhydride skeleton and a crosslinked ring structure, and / or a reactive derivative thereof This is a polyimide obtained by reacting an acyl compound with (B) an aromatic diamine, and has an imidization ratio of 95% or more and a JIS K7105 transparency test method when a film having a thickness of 20 μm is formed. A polyimide having a yellow index measured in conformity with the index of 1.5 or less.
[7] (A) A polyimide obtained by reacting at least one acyl compound selected from the group consisting of the following (a-2) component, (b) component, and (c) component with (B) an aromatic diamine. A polyimide having an imidization ratio of 85% or more and a yellow index measured according to a JIS K7105 transparency test method when a film having a thickness of 20 μm is formed is 1.5 or less. .
(A-2) a 6-membered acid anhydride skeleton having a 5-membered acid anhydride skeleton and a bridged ring structure, and at least two carbon atoms constituting the bridged ring structure forming an acid anhydride skeleton Compounds having no product skeleton, and reactive derivatives thereof (b) Compounds having a 6-membered acid anhydride skeleton and no 5-membered acid anhydride skeleton, and reactive derivatives thereof ( c) Compounds having a 5-membered acid anhydride skeleton and a 6-membered acid anhydride skeleton, and their reactive derivatives [8] Assuming that the imidization rate is 100%, the imide group concentration is The polyimide according to the above [6] or [7], which is 2.5 to 5.5 mmol / g.
[9] The polyimide according to any one of [6] to [8], wherein the polystyrene-equivalent weight average molecular weight is 50,000 to 1,000,000.
[10] The polyimide according to any one of [6] to [9], wherein the water absorption when immersed at 25 ° C. for 24 hours is less than 5% by mass.
[11] A polyimide resin composition containing the polyimide according to any one of [6] to [10] and an organic solvent.
[12] A polyimide film comprising the polyimide according to any one of [6] to [10].
[13] The film according to [12], which is for an optical member.
[14] The film according to [12], which is used for a printed wiring board.

According to the method for producing a polyimide of the present invention, since a specific imidization catalyst is used, even when aliphatic tetracarboxylic dianhydrides and their reactive derivatives are used, imidization is performed with high reactivity. be able to. Therefore, unlike the case where a conventional catalyst is used, there is no need to increase the amount of catalyst, set the reaction temperature high, increase the reaction time, etc., and polyimide can be obtained easily at low cost.
Moreover, since the obtained polyimide has the outstanding solubility with respect to the organic solvent, it can be dissolved in an organic solvent as it is, and a film can be formed.
According to the method for producing a polyimide film of the present invention, a solution containing polyimide and an organic solvent is applied to a substrate or the like to form a coating film, and then heated at a temperature at which the organic solvent in the coating film evaporates. For example, it is not necessary to perform heat treatment at a high temperature exceeding 400 ° C. as in the case of thermal imidization using a solution containing a polyamic acid and an organic solvent, so that a reduction in process load can be achieved.
The obtained polyimide film has high water resistance, and can maintain low colorability even in a heat-resistant environment or an environment exposed to ultraviolet rays, and has transparency and moldability (specifically, film-like Excellent ease of molding and small process load).
The polyimide and polyimide film of the present invention can be used for light emitting diodes, solar cells, flat display peripheral materials, specifically sealants, lenses, heat resistant transparent films, conductive transparent films, and the like.

First, the (A) component and (B) component used for the manufacturing method of the polyimide of this invention are demonstrated.
[(A) component]
The component (A) is at least one acyl compound selected from the group consisting of aliphatic tetracarboxylic dianhydrides and their reactive derivatives.
Here, the reactive derivative is a compound that can be changed to an aliphatic tetracarboxylic dianhydride, for example, a compound having two carboxyl groups instead of the anhydride of the aliphatic tetracarboxylic dianhydride, A compound in which one or both of these two carboxyl groups is an esterified product, or an acid chloride in which one or both of these two carboxyl groups are chlorinated is preferably used.

Examples of aliphatic tetracarboxylic dianhydrides and reactive derivatives thereof include compounds having a 5-membered ring anhydride skeleton, compounds having a 6-membered ring anhydride skeleton, and reactive derivatives thereof. Can do.
Specifically, the following (a) to (c) may be mentioned.
(A) a compound having two 5-membered acid anhydride skeletons and not having a 6-membered acid anhydride skeleton, and a reactive derivative thereof (b) two 6-membered anhydride skeletons And a compound having no 5-membered acid anhydride skeleton, and a reactive derivative thereof (c) a compound having a 5-membered acid anhydride skeleton and a 6-membered acid anhydride skeleton, and These reactive derivatives Further, specific examples of the component (a) include the following (a-1) to (a-2).
(A-1) a compound having a 5-membered acid anhydride skeleton and no bridged ring structure, and a reactive derivative thereof (a-2) a 5-membered acid anhydride skeleton and a bridged ring structure And a compound in which at least two carbon atoms constituting the bridged ring structure form an acid anhydride skeleton, and a reactive derivative thereof (a-1) component (a 5-membered ring acid anhydride skeleton And compounds having no bridged ring structure and reactive derivatives thereof) include, for example, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1, 2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1, 2,3,4-cyclobutanetetracarbo Acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-bicyclohexyltetracarboxylic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 3,3a, 4,5,9b-hexahydro-5-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, , 3,3a, 4,5,9b-Hexahydro 5-ethyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro -7-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b- Hexahydro-7-ethyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5 9b-Hexahydro-8-ethyl-5- (tetrahydro-2,5-dioxo- 3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5,8-dimethyl-5 (tetrahydro-2,5- Dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic Examples thereof include acid dianhydrides, compounds represented by the following formula (2), and reactive derivatives thereof.

In addition, as a compound represented by following formula (2), and these reactive derivatives, the compound represented by following formula (6) and these reactive derivatives are mentioned.

  In addition, the component (a-2) (a compound having a 5-membered acid anhydride skeleton and a crosslinked ring structure, and at least two carbon atoms constituting the crosslinked ring structure form an anhydride skeleton, and these) Examples of the reactive derivative include anhydrides having a norbornyl group, a bicyclo [2.2.2] octyl group, and the like. For example, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2,2,2] -oct-7-ene-2,3,5,6- Tetracarboxylic dianhydride, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione), 3, 5, 6 -Tricarboxy-2-carboxynorbornane-2: 3,5: 6-dianhydride, bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic dianhydride and their reactions Sex derivatives.

Examples of the compound having a 6-membered ring anhydride skeleton and reactive derivatives thereof include, for example, the component (b) (having two 6-membered acid anhydride skeletons and a 5-membered acid anhydride skeleton). And compounds having these groups and reactive derivatives thereof) and the above component (c) (compounds having a 5-membered ring acid anhydride skeleton and a 6-membered ring anhydride skeleton, and reactive derivatives thereof). Examples of the component (b) (compounds having two 6-membered acid anhydride skeletons and no 5-membered acid anhydride skeletons and reactive derivatives thereof) include, for example, the following formula (1) The compound represented by these, and these reactive derivatives are mentioned, As a specific compound, the compound represented by following formula (3)-(5), and these reactive derivatives are mentioned.

Examples of the component (c) (compounds having a 5-membered ring acid anhydride skeleton and a 6-membered ring anhydride skeleton, and reactive derivatives thereof) include, for example, 2,3,5-tricarboxycyclopentylacetic acid dianhydride Products, 3,5,6-tricarboxynorbornane-2-acetic dianhydride, and reactive derivatives thereof.
These acyl compounds are used alone or in combination of two or more.

As the reactive derivative of component (A), an anhydride (aliphatic tetracarboxylic dianhydride) is preferably used. When an anhydride is used as the component (A), a polyamic acid can be synthesized with a milder and better handleability than when a non-anhydride is used.
Moreover, as (A) component, an alicyclic tetracarboxylic dianhydride is used preferably among the above-mentioned aliphatic tetracarboxylic dianhydrides. When alicyclic tetracarboxylic dianhydride is used as the component (A), a polyimide film that is particularly excellent in transparency, non-coloring property, heat resistance and the like can be obtained.
Furthermore, as the component (A), a compound having a 6-membered acid anhydride skeleton or a compound in which at least two carbon atoms constituting the crosslinked ring structure form an anhydride skeleton is preferably used. When a compound having a 6-membered acid anhydride skeleton or a compound in which at least two carbon atoms constituting the crosslinked ring structure form an anhydride skeleton is used as the component (A), the polyimide produced is dissolved in an organic solvent. The process load can be reduced in the film forming process. Moreover, from these polyimides, a film particularly excellent in transparency, non-coloring property, heat resistance and the like can be obtained.

[Component (B)]
Component (B) is an aromatic diamine.
Specific examples of the component (B) include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether (4,4′-ODA). 3,4'-diaminodiphenyl ether (3,4'-ODA), 3,3'-diaminodiphenyl ether (3,3'-ODA), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2, 2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-bis (trifluoromethyl) 4,4′-diaminobiphenyl, 3,7-diamino-dimethyldibenzothiophene-5,5-dioxide, 4, 4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-bis (4-aminophenyl) sulfide, 4,4'-diaminodiphenyl Luhon, 4,4′-diaminobenzanilide, 1, n-bis (4-aminophenoxy) alkane, 1,3-bis [2- (4-aminophenoxyethoxy)] ethane, 9,9-bis (4- Aminophenyl) fluorene, 9,9-bis (4-aminophenoxyphenyl) fluorene, 5 (6) -amino-1- (4-aminomethyl) -1,3,3-trimethylindane, 1,4-bis ( 4-aminophenoxy) benzene (TPE-Q), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 1,3-bis (3-aminophenoxy) benzene (APB), 2,5- Bis (4-aminophenoxy) biphenyl (P-TPEQ), 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2, 2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-amino Phenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, benzidine, bis (2,2′-trifluoromethyl) benzidine, 1,3-bis (3-amino Propyl) -1,1,3,3-tetramethyldisiloxane, 3,3-dimethoxy-4,4-diaminobiphenyl, 3,3-dimethyl-4,4-diaminobiphenyl, 2,2′-dichloro-4 , 4′-diamino-5,5′-dimethoxybiphenyl, 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl, 4,4 Examples include '-methylene-bis (2-chloroaniline), 9,10-bis (4-aminophenyl) anthracene, o-tolidine sulfone and the like. These aromatic diamines can be used alone or in combination of two or more.

Next, the manufacturing method of the polyimide of this invention is demonstrated.
The manufacturing method of the polyimide of this invention includes the process of imidating the polyamic acid formed by making the said (A) acyl compound and said (B) aromatic diamine react in presence of an alicyclic tertiary monoamine. Specifically, the step (a) of preparing a solution containing a polyamic acid and an organic solvent by reacting the component (A) and the component (B), and at least a part of the polyamic acid (B) imidating in the presence of a cyclic tertiary monoamine.

[Step (a)]
Step (a) is a step of preparing a solution containing a polyamic acid obtained by reacting the component (A) with the component (B) and an organic solvent.
As a specific method for reacting the component (A) and the component (B), at least one kind of the (B) aromatic diamine is dissolved in an organic solvent, and then the resulting solution contains at least one kind. (A) The method of adding an acyl compound and stirring at the temperature of 0-100 degreeC for 1 to 60 hours is mentioned.
Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, N, N′-dimethylimidazolidinone, and tetramethyl. Aprotic polar solvents such as urea; phenolic solvents such as cresol, xylenol, and halogenated phenol; Of these, N-methyl-2-pyrrolidone and N, N-dimethylacetamide are preferable.
These solvents can be used alone or in combination of two or more.
In addition, it is preferable that the total amount of aromatic diamine and acyl compound in the reaction solution is 5 to 30% by mass of the total amount of the reaction solution.

The ratio of (A) acyl compound and (B) aromatic diamine is such that the ratio of the acid anhydride group of component (A) is 0.8 to 1.2 equivalent to 1 equivalent of amino group of component (B). A ratio of 1.0 to 1.1 equivalents is more preferable. When the amount of the acid anhydride group of the component (A) is less than 0.8 equivalent or more than 1.2 equivalent with respect to 1 equivalent of the amino group of the component (B), the molecular weight becomes low and a film can be formed. It can be difficult.
The polyamic acid is an acid having a structure containing —CO—NH— and —CO—OH, which is generated by a reaction between an acid anhydride group and an amino group, or a derivative thereof (specifically, For example, CO-NH- and -CO-OR (where R is an alkyl group or the like) are used. The polyamic acid becomes a polyimide having a cyclic chemical structure (—CO—N—CO—) by dehydrating H of —CO—NH— and OH of —CO—OH by heating or the like.

[Step (b)]
Step (b) is a step of imidizing at least a part of the polyamic acid obtained in step (a) in the presence of an alicyclic tertiary monoamine to obtain a solution containing polyimide and an organic solvent. .
As a specific imidization method, a method using a dehydrating agent (chemical imidization), or a treatment at 160 ° C. to 350 ° C. (however, a solution at 160 to 220 ° C. in a solution, and a cast film at 300 ° C. or more is common. There is a method of heat treatment (thermal imidization).
Examples of the dehydrating agent in chemical imidization include acid anhydrides such as acetic anhydride, propionic anhydride and benzoic anhydride, or corresponding acid chlorides, carbodiimide compounds such as dicyclohexylcarbodiimide, and the like. Although the addition amount of a dehydrating agent can be suitably changed according to the target imidation ratio, it is usually in the range of 1 to 10 mol and in the range of 2 to 10 mol with respect to 1 mol of the acyl compound. Is preferred.

In addition, chemical imidation can be performed at the temperature of 10 degreeC-120 degreeC, and it is preferable to carry out at the temperature of 25 degreeC-90 degreeC. When the temperature exceeds 120 ° C., coloring may not be suppressed. When the temperature is lower than 10 ° C., the reaction rate is low and imidization may take time.
In the case of thermal imidization, it is preferable to carry out while removing water generated by the dehydration reaction out of the system. At this time, water can be removed azeotropically using benzene, toluene, xylene or the like.
As the imidization method, chemical imidization is preferable because imidization can be performed by heating at a lower temperature.

（一般式（７）中、Ｒは炭素数１〜４のアルキル基、Ｘは酸素原子又は硫黄原子、ｌは０又は１、ｍ及びｎは、各々独立して、０〜２の整数である。）
式（７）中、Ｒは、メチル基又はエチル基であることが好ましく、メチル基であることが特に好ましい。また、ｍ、ｎは、好ましくは０又は１である。さらに、ｍ＋ｎは１〜３であることが好ましい。
上記式（７）で表される化合物の好適な例としては、Ｎ−メチルピペリジン、Ｎ−メチルピロリジン、Ｎ−メチルモルフォリンなどが挙げられる。 In the imidization, an alicyclic tertiary monoamine is used as an imidization catalyst. When an alicyclic tertiary monoamine compound is used for imidization, the imidization reaction is promoted because the lone pair on the nitrogen atom of the alicyclic tertiary monoamine compound has high nucleophilicity. Conceivable.
As said alicyclic tertiary monoamine, the compound represented by following formula (7) is used suitably.

(In General Formula (7), R is an alkyl group having 1 to 4 carbon atoms, X is an oxygen atom or a sulfur atom, l is 0 or 1, and m and n are each independently an integer of 0 to 2. .)
In formula (7), R is preferably a methyl group or an ethyl group, and particularly preferably a methyl group. M and n are preferably 0 or 1. Furthermore, m + n is preferably 1 to 3.
Preferable examples of the compound represented by the formula (7) include N-methylpiperidine, N-methylpyrrolidine, N-methylmorpholine and the like.

By using an alicyclic tertiary monoamine as an imidization catalyst, even if an aliphatic compound is used as the component (A), it can be imidized with high reactivity (imidation reaction rate), and at a lower temperature. Imidization and shortening of the time required for imidization can be achieved. As a result, it is possible to reduce the coloring of the resulting polyimide.
When the above component (a-1) (a compound having a 5-membered ring acid anhydride skeleton and no cross-linked ring structure and a reactive derivative thereof) is used as the component (A), 90 ° C. is used. A high imidation ratio (for example, 95% or more) that could not be achieved even under high temperature conditions can be achieved under low temperature conditions of 90 ° C. or lower. The imidation ratio is preferably 95% or more, more preferably 97% or more.
Further, the component (b) (compound having a 6-membered acid anhydride skeleton and no 5-membered acid anhydride skeleton, and a reactive derivative thereof) and the component (c) (5-membered) Compounds having a 6-membered ring anhydride skeleton, such as compounds having a ring acid anhydride skeleton and a 6-membered ring acid anhydride skeleton, and reactive derivatives thereof, or the component (a-2) (5 members) A compound having a cyclic acid anhydride skeleton and a bridged ring structure, and at least two carbon atoms constituting the bridged ring structure forming an anhydride skeleton, and reactive derivatives thereof). In particular, when a compound that is difficult to proceed with imidization, such as a compound in which at least two carbons constituting an anhydride skeleton are used as the component (A), it could not be achieved conventionally even under a low temperature condition of 60 ° C. or lower. High imidization rate (example If it is possible to achieve a 85% or higher). The imidation ratio is preferably 85% or more, more preferably 90% or more, and particularly preferably 95% or more.
The alicyclic tertiary monoamine is preferably used in the range of 0.01 to 10 mol, particularly preferably in the range of 0.1 to 5 mol, relative to 1 mol of the acyl compound.
In the imidization, if necessary, other basic compounds such as pyridine, isoquinoline, trimethylamine, triethylamine, N, N-dimethylaminopyridine, and imidazole can be used in combination.

The imidization is performed so as to imidize at least a part of the polyamic acid, preferably 75 mol% or more, more preferably 85 mol% or more, and particularly preferably 95 mol% or more.
The obtained solution containing the polyimide and the organic solvent can be used as it is, but after isolating the polyimide as a solid component, it can also be used by re-dissolving in an organic solvent. In addition, as an organic solvent which redissolves, the thing similar to the said organic solvent is mentioned. As a method for isolating the polyimide, a solution containing the polyimide and the organic solvent is poured into a poor solvent for the polyimide such as methanol to precipitate the polyimide, and the polyimide is separated as a solid by filtration, washing, drying, etc. Is mentioned. By performing such an operation, it is possible to remove the dehydration catalyst (imidization catalyst) used in the imidization.
The resulting polyimide preferably has a polystyrene-equivalent weight average molecular weight of 50,000 to 1,000,000, more preferably 80,000 to 800,000, and 100,000 to 600,000. More preferably. When the weight average molecular weight is within the above range, the mechanical properties can be sufficiently expressed.

Next, the manufacturing method of the polyimide film of this invention is demonstrated.
The method for producing a polyimide film of the present invention includes a step (c) of forming a coating film by applying a solution containing the above polyimide and an organic solvent on a substrate, and removing the organic solvent by evaporating the coating film from the coating film. And a step (d) of obtaining a polyimide film.
[Step (c)]
Step (c) is a step of forming a coating film by applying a solution containing the polyimide and the organic solvent on the substrate.
Examples of the substrate include a polyethylene terephthalate (PET) film, a SUS plate, and a copper foil.
As a method for applying a solution containing polyimide and an organic solvent on the substrate, a roll coating method, a gravure coating method, a spin coating method, a method using a doctor blade, or the like can be used.
Although the thickness of a coating film is not specifically limited, For example, it is 1-250 micrometers.

[Step (d)]
Step (d) is a step of obtaining a polyimide film by evaporating and removing the organic solvent from the coating film.
Specifically, the organic solvent in the coating film is evaporated and removed by heating the coating film.
The heating condition is not particularly limited as long as the organic solvent evaporates. For example, the heating condition is 60 to 250 ° C. for 1 to 5 hours. Heating may be performed in two stages. For example, after heating at 100 ° C. for 30 minutes, heating at 150 ° C. for 1 hour. Further, if necessary, drying may be performed under a nitrogen atmosphere or under reduced pressure.
In this step, it is sufficient if the organic solvent can be removed, and it is not necessary to perform imidization. Therefore, a film can be obtained at a lower temperature than in the prior art. Therefore, even if other members forming the optical member have low heat resistance, a film is obtained by directly applying a solution containing polyimide or the like and an organic solvent to the member and evaporating and removing the organic solvent. Can be formed.
The obtained film can be used as it is without being peeled off from the substrate.

The polyimide film of the present invention is mainly composed of polyimide obtained by reacting the component (A) and the component (B).
Here, for example, the component (A) is 2,3,5-tricarboxycyclopentylacetic acid dianhydride, and the component (B) is 2,2-bis [4- (4-aminophenoxy) phenyl] propane. In some cases, the polyamic acid has at least one repeating unit represented by the following formulas (8) to (11).

Furthermore, in this case, the polyimide formed by the reaction of the component (A) and the component (B) has a repeating unit represented by the following formula (12) or (13), for example.

The film of the present invention has a thickness of 1 to 250 μm, preferably 5 to 200 μm. Moreover, when using the film of this invention as a base material, it is especially preferable that it is 10-150 micrometers.
The film of the present invention has a total light transmittance of preferably 80% or more, more preferably 85% or more, and further preferably 89% or more when the thickness is 20 μm.
The YI value (yellow index) of the film of the present invention can be measured, for example, according to the JIS K7105 transparency test method. When the thickness is 20 μm, it is preferably 2.5 or less, more preferably 2. 1 or less, more preferably 1.5 or less.
The film of the present invention has a glass transition temperature (Tg) of preferably 250 ° C. or higher, and more preferably 280 ° C. or higher. By having such a glass transition temperature, excellent heat resistance can be obtained.
The film of the present invention preferably has a water absorption rate of less than 5% by mass, preferably less than 2.5% by mass, more preferably 2.4% by mass or less, and 2.2% by mass or less. It is particularly preferred that In addition, the said water absorption is a water absorption measured by the measuring method shown in the following Example.
The film of the present invention can be used for light emitting diode peripheral materials, solar cell peripheral materials, flat display peripheral materials, and electronic circuit peripheral materials. Specifically, it can be used for optical members such as heat-resistant transparent films and conductive transparent films. Moreover, as an electronic circuit peripheral material, it can also be used as a printed wiring board substrate, a flexible printed wiring board, a rigid printed wiring board, an optoelectronic printed wiring board, a COF (Chip on Film) board, a TAB ( A substrate for Tape Automated Bonding) can be given. When used as a printed wiring board, for example, a copper layer for wiring can be provided. Examples of a method for providing a copper layer on the film of the present invention include a laminating method and a metalizing method. In the case of the laminating method, for example, a printed wiring board provided with a copper layer can be produced by hot pressing a copper foil on the film of the present invention. In the case of the metalizing method, for example, after the surface modification is performed in order to develop the affinity of the film of the present invention with the metal, the Ni-based metal layer bonded to the polyimide by vapor deposition or sputtering is used. A seed layer necessary for wet electroplating is formed. And the board | substrate for printed wiring with which the copper layer was provided can be manufactured by providing the copper layer of a predetermined film thickness with a wet-plating method.

Moreover, the polyimide-type solution containing the polyimide etc. and organic solvent obtained by process (a), (b) is a light emitting diode peripheral material, a solar cell peripheral material, a flat display peripheral material, an electron as a polyimide-type resin composition. It can also be used as a circuit peripheral material. Specifically, it can be used as a sealant, a lens material, a printed wiring board forming material, a liquid crystal alignment film forming material, and the like. For example, when used as a printed wiring board forming material, a printed wiring board can be manufactured by a casting method. Specifically, a printed wiring board provided with a copper layer can be produced by applying a heat treatment after applying the polyimide resin composition on a copper foil.
In addition, the said polyimide resin composition can use the organic solvent whose boiling point is 150 degrees C or less as a cosolvent. Examples of the organic solvent include methanol, ethanol, isopropanol, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane and the like.
These solvents can be used alone or in combination of two or more.
In addition, it is preferable that the density | concentration of the polyamic acid in a polyimide-type resin composition and / or a polyimide is 5-30 mass% of the reaction liquid whole quantity.

Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to these examples.
[Example 1]
2,2-bis [4- (4-aminophenoxy) phenyl] propane (6.47 g, 15.8 mmol) was added to a 300 mL four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a condenser tube. Next, after the atmosphere in the flask was replaced with nitrogen, N-methyl-2-pyrrolidone (hereinafter referred to as NMP) (90.0 g) was added and stirred until uniform. 2,3,5-Tricarboxycyclopentylacetic acid dianhydride (3.53 g, 15.8 mmol) was added to the resulting solution at room temperature, and stirring was continued at that temperature for 24 hours to obtain a polyamic acid solution.
Next, N-methylpiperidine (1.9 ml) and acetic anhydride (4.5 ml) were added to the obtained polyamic acid solution, and the mixture was stirred at 75 ° C. for 4 hours for imidization. After cooling to room temperature, it was poured into a large amount of methanol, and the polymer was isolated by filtration. The obtained polymer was vacuum-dried overnight at 60 ° C. to obtain a white powder (yield 9.20 g, yield 97.5% by mass).
Subsequently, the obtained polymer was redissolved in N, N-dimethylacetamide (DMAc) to obtain a 20% by mass resin solution. Then, the resin solution was applied onto a substrate made of polyethylene terephthalate (PET) using a doctor blade (100 μm gap), dried at 100 ° C. for 30 minutes and further at 150 ° C. for 60 minutes, and then peeled off from the PET substrate. Thereafter, the film was further dried at 180 ° C. under reduced pressure for 8 hours to obtain a film having a thickness of 20 μm.
About the said polymer, the ring closure rate (imidation rate) and the weight average molecular weight were evaluated by the following method. Further, the total light transmittance, YI value (initial, after heat test, after UV resistance test), and water absorption of the film were evaluated by the following methods. The results are shown in Table 1.

(1) Ring closure rate (imidation rate)
The ring closure rate of the polyimide was measured using 1H-NMR. D-DMSO was used as a solvent. The ring closure rate was calculated from the ratio between the peak integral value of the amide in the amic acid part (9.8 to 10.3 ppm) and the peak integral value of the aromatic diamine (6.5 to 7.5 ppm).
(2) Weight average molecular weight The weight average molecular weight was measured for each of the polyamic acid and the polymer after imidization. The weight average molecular weight was measured using a TOSOH HLC-8020 GPC apparatus, the solvent was N-methyl-2-pyrrolidone (NMP) to which lithium bromide and phosphoric acid were added, and the measurement temperature was 40 ° C. The molecular weight in terms of polystyrene was determined.
(3) Total light transmittance, YI value (initial)
It measured according to the JIS K7105 transparency test method. Specifically, the total light transmittance of the film (5 cm square) and the YI value (yellow index) immediately after film formation were measured using an SC-3H haze meter manufactured by Suga Test Instruments Co., Ltd.
(4) YI value after heat resistance test The obtained film (5 cm square) was placed in a hot air drier maintained at 150 ° C. for 100 hours to conduct a heat resistance acceleration test. The YI value of the film after the test was measured by the same method as in (3) above.
(5) YI value after UV resistance test The obtained film (5 cm square) is placed in a QUV tester (accelerated weather resistance tester) using an ultraviolet fluorescent lamp UVA-351 as a light source for one week, and UV accelerated test Went. The YI value of the film after the test was measured by the same method as in (3) above.
(6) Water absorption test Three pieces of the obtained film were cut into a size of 3 cm × 4 cm and dried at 180 ° C. for 8 hours under reduced pressure drying. After measuring the mass of the film, the film was immersed in distilled water at 25 ° C. for 24 hours. After immersion, water droplets on the film surface were wiped off, and the water absorption (mass%) was calculated from the mass change before and after immersion.
The calculation formula of the water absorption rate is as follows.
Water absorption rate (%) = {[(mass after soaking) ÷ (mass before soaking)]-1} × 100

[Example 2]
A polymer composed of a white powder (yield 9.20 g, yield 97.5 mass%) and a film were obtained in the same manner as in Example 1 except that the temperature of the imidization reaction was 40 ° C. and the reaction time was 48 hours. .
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.
[Example 3]
Instead of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 3.79 g (15.8 mmol) of bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride The amount of each of 2,2-bis [4- (4-aminophenoxy) phenyl] propane, N-methylpiperidine, and acetic anhydride used was 6.21 g (15.1 mmol), 1.8 ml, and 4. A polymer (yield 9.20 g, yield 97.3% by mass) and a film were obtained in the same manner as in Example 1 except that the amount was changed to 3 ml.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.

[Example 4]
Instead of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 4.27 g (14.0 mmol) of 3,3 ′, 4,4′-bicyclohexyltetracarboxylic dianhydride was used. The amount of each of bis [4- (4-aminophenoxy) phenyl] propane (BAPP), N-methylpiperidine, and acetic anhydride is adjusted to 5.73 g (14.0 mmol), 1.7 ml, and 2.9 ml. A polymer (yield: 9.21 g, yield: 97.0% by mass) consisting of a white powder and a film were obtained in the same manner as Example 1 except for the change.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.

[Comparative Example 1]
A white powder was obtained in the same manner as in Example 1 except that pyridine (7.6 ml) and acetic anhydride (4.5 ml) were added to the obtained polyamic acid solution, and imidization was carried out at 110 ° C. for 4 hours. A polymer (yield: 9.19 g, yield: 97.4% by mass) and a film were obtained.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.
[Comparative Example 2]
A polymer composed of a white powder (yield 9.19 g, yield 97.4% by mass) and a film were obtained in the same manner as in Comparative Example 1 except that the temperature of the imidization reaction was 75 ° C.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.

[Comparative Example 3]
A polymer (yield 9.19 g, 97.4% by mass) consisting of a pale yellow powder and a film were obtained in the same manner as in Comparative Example 1 except that triethylamine (9.7 ml) was added as the catalyst to be added during the imidization reaction. It was.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.
[Comparative Example 4]
A polymer (yield 9.19 g, 97.4% by mass) and a film made of a pale yellow powder were obtained in the same manner as in Comparative Example 3 except that the reaction temperature of the imidization reaction was 75 ° C.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.

[Comparative Example 5]
A white powder was obtained in the same manner as in Example 3 except that pyridine (7.3 ml) and acetic anhydride (4.3 ml) were added to the obtained polyamic acid solution, and imidization was carried out at 75 ° C. for 4 hours. A polymer (yield: 9.14 g, yield: 96.7% by mass) and a film were obtained.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.
[Comparative Example 6]
A white powder was obtained in the same manner as in Example 3 except that pyridine (6.7 ml) and acetic anhydride (3.9 ml) were added to the obtained polyamic acid solution, and imidization was carried out at 75 ° C. for 4 hours. The polymer which consists of (yield 9.20g, yield 98.7 mass%), and the film were obtained.
The polymer was evaluated for ring closure rate (imidation rate), weight average molecular weight, total light transmittance of the film, YI value (initial, after heat test, after UV resistance test), and water absorption in the same manner as in Example 1. did. The results are shown in Table 1.

  From Table 1, it can be seen that according to the present invention, since a specific catalyst is used, imidization can be performed at a lower temperature than in the prior art. Moreover, since the obtained polyimide has the outstanding solubility with respect to the organic solvent, it can form a film, without heat-processing at high temperature (for example, about 400 degreeC). Further, from Table 1, the films of the present invention (Examples 1 to 4) have high transparency (total light transmittance), and yellow immediately after film formation, after heat resistance test, and after UV resistance test. It can be seen that there is little change and the water absorption is low. On the other hand, in Comparative Examples 1 to 6 using those other than the present invention as the imidization catalyst, it can be seen that the YI value (immediately after film formation, after the heat resistance test, after the UV resistance test) is high, and the water absorption is high.

Claims (14)

  (A) A polyamic acid obtained by reacting at least one acyl compound selected from aliphatic tetracarboxylic dianhydrides and their reactive derivatives with (B) an aromatic diamine is used as an alicyclic tertiary monoamine. A method for producing polyimide, comprising imidization in the presence. The method for producing a polyimide according to claim 1, wherein the alicyclic tertiary monoamine is a compound represented by the following formula (7).

(In the formula (7), R is an alkyl group having 1 to 4 carbon atoms, X is an oxygen atom or sulfur atom, l is 0 or 1, and m and n are each independently an integer of 0 to 2. .)   The method for producing a polyimide according to claim 1 or 2, wherein the component (A) is an aliphatic tetracarboxylic dianhydride having a 5-membered and / or 6-membered acid anhydride skeleton.   Further, claim using at least one dehydrating agent selected from the group consisting of acetic anhydride, propionic anhydride, benzoic anhydride, acid chlorides corresponding to these anhydrides, and carbodiimide compounds Item 4. The method for producing polyimide according to any one of Items 1 to 3.   The process of apply | coating the solution containing the polyimide and organic solvent which were obtained by the method of any one of Claims 1-4 on a board | substrate, and forming a coating film, and evaporating and removing the said organic solvent from this coating film And a step of removing the resulting film to obtain a film.   (A) (a-1) a compound having a 5-membered ring acid anhydride skeleton and not having a 6-membered acid anhydride skeleton and a crosslinked ring structure, and / or an acyl which is a reactive derivative thereof A polyimide obtained by reacting a compound and (B) an aromatic diamine, and measured according to the JIS K7105 transparency test method when an imidation rate is 95% or more and a film having a thickness of 20 μm is formed. A polyimide having a yellow index of 1.5 or less. (A) A polyimide obtained by reacting at least one acyl compound selected from the group consisting of the following (a-2) component, (b) component, and (c) component with (B) an aromatic diamine. A polyimide having a yellow index of 1.5 or less measured according to the JIS K7105 transparency test method when an imidation ratio is 85% or more and a film having a thickness of 20 μm is formed.
(A-2) a 6-membered acid anhydride skeleton having a 5-membered acid anhydride skeleton and a bridged ring structure, and at least two carbon atoms constituting the bridged ring structure forming an acid anhydride skeleton Compounds having no product skeleton, and reactive derivatives thereof (b) Compounds having a 6-membered acid anhydride skeleton and no 5-membered acid anhydride skeleton, and reactive derivatives thereof ( c) Compounds having a 5-membered acid anhydride skeleton and a 6-membered acid anhydride skeleton, and reactive derivatives thereof   The polyimide according to claim 6 or 7, wherein the imide group concentration is 2.5 to 5.5 mmol / g when the imidation ratio is assumed to be 100%.   The polyimide according to any one of claims 6 to 8, which has a weight average molecular weight in terms of polystyrene of 50,000 to 1,000,000.   The polyimide according to any one of claims 6 to 9, which has a water absorption rate of less than 5 mass% when immersed for 24 hours at 25 ° C.   The polyimide resin composition containing the polyimide of any one of Claims 6-10, and an organic solvent.   The polyimide film which consists of a polyimide of any one of Claims 6-10.   The film according to claim 12, which is used for an optical member.   The film according to claim 12, which is for a printed wiring board.