JP7384170B2 - Polyimide resin, polyimide varnish and polyimide film - Google Patents

Description

The present invention relates to polyimide resins, polyimide varnishes, and polyimide films.

Various uses of polyimide resins are being considered in fields such as electrical and electronic parts. For example, it is desired to replace the glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates in order to make the devices lighter and more flexible. Research is underway.
In an image display device, when light emitted from a display element passes through a plastic substrate, the plastic substrate is required to be colorless and transparent; furthermore, when light passes through a retardation film or a polarizing plate ( For example, liquid crystal displays, touch panels, etc.) are required to have high optical isotropy (ie, low Rth) in addition to colorless transparency.

Various polyimide resins are being developed in order to meet the above-mentioned performance requirements. For example, Patent Document 1 describes that 3,3'-diaminodiphenylsulfone (primary diamine) and 4,4'-diaminodiphenylsulfone are used as polyimide resins that provide a polyimide film that is colorless and transparent, has a low Rth, and has excellent toughness. A polyimide resin produced using a combination of a specific diamine (secondary diamine) as a diamine component is described.

International Publication No. 2016/158825

Incidentally, in order for a polyimide film to be suitable as a substrate, not only colorless transparency and optical isotropy but also chemical resistance (solvent resistance, acid resistance, and alkali resistance) are important physical properties.
For example, when applying a varnish for forming a resin layer to a polyimide film in order to form another resin layer (e.g., color filter, resist) on the polyimide film, the solvent contained in the varnish may be applied to the polyimide film. Requires resistance to If the solvent resistance of the polyimide film is insufficient, the film may dissolve or swell, making it useless as a substrate.
Further, when a 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 lose its colorless transparency.
In addition, alkaline aqueous solutions such as sodium hydroxide aqueous solution and potassium hydroxide aqueous solution are mainly used to clean supports such as glass plates used when manufacturing polyimide films (supports to which polyimide varnish is applied). . Cleaning with an alkaline aqueous solution may be performed even when a polyimide film is formed on a support such as a glass plate. Therefore, polyimide films are also required to have resistance to alkalis.
However, in Patent Document 1, chemical resistance is not evaluated.

The present invention was made in view of these circumstances, and an object of the present invention is to provide a film that has excellent colorless transparency, optical isotropy, and chemical resistance (solvent resistance, acid resistance, and alkali resistance). An object of the present invention is to provide a polyimide resin capable of forming a polyimide resin, as well as a polyimide varnish and a polyimide film containing the polyimide resin.

The present inventors have discovered that a polyimide resin containing a combination of specific structural units can solve the above problems, and have completed the invention.

That is, the present invention relates to the following [1] to [4].
[1]
A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine,
A structural unit (A-1) in which structural unit A is derived from a compound represented by the following formula (a-1), and a structural unit (A-2) derived from a compound represented by the following formula (a-2) including
Structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1),
A polyimide resin in which the ratio of the structural unit (B-1) in the structural unit B is 70 mol% or more.

[2]
The ratio of the structural unit (A-1) in the structural unit A is 5 to 95 mol%,
The polyimide resin according to [1] above, wherein the ratio of the structural unit (A-2) in the structural unit A is 5 to 95 mol%.
[3]
A polyimide varnish obtained by dissolving the polyimide resin described in [1] or [2] above in an organic solvent.
[4]
A polyimide film comprising the polyimide resin described in [1] or [2] above.

According to the present invention, a film can be formed that has excellent colorless transparency, optical isotropy, and chemical resistance (solvent resistance, acid resistance, and alkali resistance).

[Polyimide resin]
The polyimide resin of the present invention has a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, and the structural unit A is derived from a compound represented by the following formula (a-1). Contains a structural unit (A-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2), and the structural unit B is represented by the following formula (b-1). Contains a structural unit (B-1) derived from a compound, and the ratio of the structural unit (B-1) in the structural unit B is 70 mol% or more.

<Constituent unit A>
Structural unit A is a structural unit derived from tetracarboxylic dianhydride that occupies the polyimide resin, and comprises a structural unit (A-1) derived from a compound represented by the following formula (a-1), and a structural unit derived from the following formula (a-1). Contains a structural unit (A-2) derived from the compound represented by (a-2).

The compound represented by formula (a-1) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.
The compound represented by formula (a-2) is 4,4'-oxydiphthalic anhydride.
When the structural unit A contains both the structural unit (A-1) and the structural unit (A-2), the colorless transparency, optical isotropy, and chemical resistance of the film can be improved. The structural unit (A-1) particularly makes a large contribution to improving colorless transparency and optical isotropy, and the structural unit (A-2) particularly makes a large contribution to improving chemical resistance.

The ratio of the structural unit (A-1) in the structural unit A is preferably 5 to 95 mol%, more preferably 15 to 95 mol%, and it improves the colorless transparency, optical isotropy, and From the viewpoint of improving chemical resistance, the content is more preferably 20 to 90 mol%, particularly preferably 50 to 90 mol%. On the other hand, especially from the viewpoint of optical isotropy and acid resistance, the content is more preferably 70 to 95 mol%, particularly preferably 85 to 95 mol%.
The ratio of the structural unit (A-2) in the structural unit A is preferably 5 to 95 mol%, more preferably 5 to 85 mol%, and it improves the colorless transparency, optical isotropy, and From the viewpoint of improving chemical resistance, the content is more preferably 10 to 80 mol%, particularly preferably 10 to 50 mol%. On the other hand, especially from the viewpoint of optical isotropy and acid resistance, the content is more preferably 5 to 30 mol%, particularly preferably 5 to 15 mol%.
The total ratio of structural units (A-1) and (A-2) in structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more. and particularly preferably 99 mol% or more. The upper limit of the total ratio of structural units (A-1) and (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).

The structural unit A may include structural units other than the structural units (A-1) and (A-2). Tetracarboxylic dianhydrides providing such structural units include, but are not particularly limited to, pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 9,9' Aromatic tetracarboxylic dianhydrides such as -bis(3,4-dicarboxyphenyl)fluorene dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (provided that the formula (a-2 ); 1,2,3,4-cyclobutanetetracarboxylic dianhydride and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5 , 5'',6,6''-alicyclic tetracarboxylic dianhydride such as tetracarboxylic dianhydride (excluding compounds represented by formula (a-1)); and 1,2 , 3,4-butanetetracarboxylic dianhydride and other aliphatic tetracarboxylic dianhydrides.
In addition, in this specification, aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and alicyclic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more alicyclic rings. The term "aliphatic tetracarboxylic dianhydride" refers to a tetracarboxylic dianhydride containing the above and not containing an aromatic ring, and the term "aliphatic tetracarboxylic dianhydride" refers to a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.
The number of structural units optionally included in structural unit A (that is, structural units other than structural units (A-1) and (A-2)) may be one type or two or more types.

<Constituent unit B>
The structural unit B is a structural unit derived from a diamine that occupies the polyimide resin, and includes a structural unit (B-1) derived from a compound represented by the following formula (b-1).

The compound represented by formula (b-1) is 3,3'-diaminodiphenylsulfone.
When the structural unit B contains the structural unit (B-1), the optical isotropy and chemical resistance of the film can be improved. Among these, acid resistance can be improved.

The ratio of the structural unit (B-1) in the structural unit B is 70 mol% or more. The ratio is preferably 75 mol% or more, more preferably 80 mol% or more. The upper limit of the ratio of the structural unit (B-1) may be 90 mol%, 95 mol%, 99 mol%, or 100 mol%. The structural unit B may consist only of the structural unit (B-1).
By containing the structural unit (B-1) in an amount of 70 mol % or more in the structural unit B, the structural unit B maintains the chemical resistance of the film and is uniformly dissolved in the organic solvent used for the polyimide varnish described below. Therefore, the obtained film is considered to have excellent colorless transparency.

The structural unit B may include structural units other than the structural unit (B-1). Diamines that provide such structural units include, but are not particularly limited to, 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, 1,5-diaminonaphthalene, 2,2'-dimethyl Biphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl) hexa Fluoropropane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5- Amine, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl , 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 9,9-bis(4-aminophenyl) Aromatic diamines such as fluorene and 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether (excluding compounds represented by formula (b-1)); 1,3-bis(aminomethyl ) cycloaliphatic diamines such as cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylene diamine.
In addition, in this specification, aromatic diamine means a diamine containing one or more aromatic rings, alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, Group diamine means a diamine containing neither aromatic ring nor alicyclic ring.
The number of structural units optionally included in the structural unit B (ie, structural units other than the structural unit (B-1)) may be one or two or more types.

（式（ｂ－２－２）中、Ｒはそれぞれ独立して、水素原子、フッ素原子又はメチル基である。）Examples of diamines that provide structural units that are optionally included in structural unit B include compounds represented by the following formula (b-2-1), compounds represented by the following formula (b-2-2), and the following formula (b-2-1); -2-3) and a compound represented by the following formula (b-2-4) are preferred. That is, in the polyimide resin of one embodiment of the present invention, the structural unit B is a structural unit (B-2-1) derived from a compound represented by the following formula (b-2-1), a structural unit (B-2-1) derived from a compound represented by the following formula (b-2 A structural unit (B-2-2) derived from a compound represented by -2), a structural unit (B-2-3) derived from a compound represented by the following formula (b-2-3), and the following It may further contain a structural unit (B-2) that is at least one selected from the group consisting of structural units (B-2-4) derived from the compound represented by formula (b-2-4).

(In formula (b-2-2), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.)

The compound represented by formula (b-2-1) is 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl ether.
When the structural unit B contains the structural unit (B-2-1), the colorless transparency of the film can be improved.

In formula (b-2-2), each R is independently a hydrogen atom, a fluorine atom, or a methyl group, and preferably a hydrogen atom. Examples of the compound represented by formula (b-2-2) include 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, and 9,9-bis(4-aminophenyl)fluorene. -bis(3-methyl-4-aminophenyl)fluorene and the like, with 9,9-bis(4-aminophenyl)fluorene being preferred.
When the structural unit B contains the structural unit (B-2-2), the optical isotropy and heat resistance of the film can be improved.

The compound represented by formula (b-2-3) is 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane.
When the structural unit B contains the structural unit (B-2-3), the colorless transparency and optical isotropy of the film can be improved.

The compound represented by formula (b-2-4) is 2,2'-bis(trifluoromethyl)benzidine.
When the structural unit B contains the structural unit (B-2-4), the colorless transparency, chemical resistance, heat resistance, and mechanical properties of the film can be improved.

From the viewpoint of improving various performances of the film, the structural unit B is a structural unit (B-2-1) derived from a compound represented by formula (b-2-1) as the structural unit (B-2). , a structural unit derived from a compound represented by formula (b-2-2) (B-2-2), a structural unit derived from a compound represented by formula (b-2-3) (B-2- 3), and a structural unit (B-2-4) derived from a compound represented by formula (b-2-4). From the viewpoint of improving the optical isotropy, it is preferable that the structural unit B includes a structural unit (B-2-3) derived from a compound represented by the formula (b-2-3).

When the structural unit B contains the structural unit (B-1) and the structural unit (B-2), the ratio of the structural unit (B-1) in the structural unit B is preferably 70 to 95 mol%, and more Preferably it is 75 to 95 mol%, more preferably 75 to 90 mol%, and the ratio of the structural unit (B-2) in structural unit B is preferably 5 to 30 mol%, more preferably It is 5 to 25 mol%, more preferably 10 to 25 mol%.
The total ratio of the structural unit (B-1) and the structural unit (B-2) in the structural unit B is preferably 75 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol%. % or more, particularly preferably 99 mol% or more. The upper limit of the total ratio of the structural unit (B-1) and the structural unit (B-2) is not particularly limited, that is, 100 mol%. The structural unit B may consist only of the structural unit (B-1) and the structural unit (B-2).

The structural unit (B-2) may be only the structural unit (B-2-1), may be only the structural unit (B-2-2), or the structural unit (B-2-3). or only the structural unit (B-2-4).
Further, the structural unit (B-2) may be a combination of two or more structural units selected from the group consisting of structural units (B-2-1) to (B-2-4).

The number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 200,000 from the viewpoint of mechanical strength of the polyimide film obtained. Note that the number average molecular weight of the polyimide resin can be determined, for example, from a standard polymethyl methacrylate (PMMA) equivalent value measured by gel filtration chromatography.

The polyimide resin of the present invention may include a structure other than a polyimide chain (a structure formed by imide bonding of structural unit A and structural unit B). Structures other than polyimide chains that may be included in the polyimide resin include, for example, structures containing amide bonds.
The polyimide resin of the present invention preferably contains a polyimide chain (a structure formed by imide bonding of structural unit A and structural unit B) as a main structure. Therefore, the proportion of polyimide chains in the polyimide resin of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and particularly preferably 99% by mass. % or more.

By using the polyimide resin of the present invention, a film having excellent colorless transparency, optical isotropy, and chemical resistance can be formed, and the preferable physical properties of the film are as follows.
The total light transmittance is preferably 88% or more, more preferably 88.5% or more, and even more preferably 89% or more when the film has a thickness of 10 μm.
The yellow index (YI) is preferably 4.0 or less, more preferably 2.5 or less, still more preferably 2.0 or less when the film has a thickness of 10 μm.
b ^* is preferably 2.0 or less, more preferably 1.2 or less, and still more preferably 1.0 or less when the film has a thickness of 10 μm.
The absolute value of the thickness retardation (Rth) is preferably 70 nm or less, more preferably 60 nm or less, and still more preferably 50 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 even more preferably 1.0 or less when a film having a thickness of 10 μm is formed.
The mixed acid Δb ^* is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.5 or less when the film is 10 μm thick.
Note that mixed acid ΔYI and mixed acid Δb ^* mean the difference in YI and b ^* before and after immersion, respectively, when a polyimide film is immersed in a mixture of phosphoric acid, nitric acid, and acetic acid. It can be measured by the method described in the example. It means that the smaller ΔYI and Δb ^* are, the better the acid resistance is. By using the polyimide resin of the present invention, a film with excellent chemical resistance can be formed and shows excellent resistance to acids. In particular, a mixed acid (for example, a mixed solution of 50 to 97% by mass of phosphoric acid, 1 to 20% by mass of nitric acid, 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) % by mass, a mixed solution of 5 to 15 mass % nitric acid, 3 to 7 mass % acetic acid, and 5 to 15 mass % water).

The film that can be formed using the polyimide resin of the present invention has good mechanical properties and heat resistance, and has the following suitable physical property values.
The tensile strength is preferably 60 MPa or more, more preferably 70 MPa or more, still more preferably 80 MPa or more.
The tensile modulus is preferably 2.0 GPa or more, more preferably 2.5 GPa or more, still more preferably 3.0 GPa or more.
The glass transition temperature (Tg) is preferably 230°C or higher, more preferably 250°C or higher, even more preferably 270°C or higher.
In addition, the above-mentioned physical property values in the present invention can be specifically measured by the method described in the Examples.

[Production method of polyimide resin]
The polyimide resin of the present invention contains a tetracarboxylic acid component containing a compound that provides the above-mentioned structural unit (A-1) and a compound that provides the above-mentioned structural unit (A-2), and the above-mentioned structural unit (B-1). It can be produced by reacting the given compound with a diamine component containing 70 mol% or more.

Examples of the compound that provides the structural unit (A-1) include the compound represented by formula (a-1), but the compound is not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. The derivatives include the tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by formula (a-1) (i.e., 1,2,4,5-cyclohexanetetracarboxylic acid) and the alkyl of the tetracarboxylic acid. Examples include esters. As the compound providing structural unit (A-1), a compound represented by formula (a-1) (ie, dianhydride) is preferable.
Similarly, the compound that provides the structural unit (A-2) includes the compound represented by formula (a-2), but is not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. . Examples of such derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by formula (a-2) and alkyl esters of the tetracarboxylic acids. As the compound providing structural unit (A-2), a compound represented by formula (a-2) (ie, dianhydride) is preferable.

The tetracarboxylic acid component preferably contains 5 to 95 mol%, more preferably 15 to 95 mol%, of a compound that provides the structural unit (A-1), and improves colorless transparency, optical isotropy, and From the viewpoint of improving chemical resistance, the content is more preferably 20 to 90 mol%, particularly preferably 50 to 90 mol%. On the other hand, especially from the viewpoint of optical isotropy and acid resistance, the content is more preferably 70 to 95 mol%, particularly preferably 85 to 95 mol%.
The tetracarboxylic acid component preferably contains 5 to 95 mol%, more preferably 5 to 85 mol%, of a compound that provides the structural unit (A-2), and improves colorless transparency, optical isotropy, and From the viewpoint of improving chemical resistance, the content is more preferably 10 to 80 mol%, particularly preferably 10 to 50 mol%. On the other hand, especially from the viewpoint of optical isotropy and acid resistance, it is more preferably contained in an amount of 5 to 30 mol%, particularly preferably 5 to 15 mol%.
The tetracarboxylic acid component preferably contains a total of 50 mol% or more, more preferably 70 mol% or more, and even more preferably contains 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the total content ratio of the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist only of a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2).

The tetracarboxylic acid component may contain compounds other than the compound that provides the structural unit (A-1) and the compound that provides the structural unit (A-2), such as the above-mentioned aromatic tetracarboxylic dianhydride. , alicyclic tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.).
The number of compounds optionally included in the tetracarboxylic acid component (that is, compounds other than the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2)) may be one type, or two or more types. There may be.

Examples of the compound that provides the structural unit (B-1) include the compound represented by formula (b-1), but the compound is not limited thereto, and derivatives thereof may be used as long as they provide the same structural unit. Examples of such derivatives include diisocyanates corresponding to the diamine represented by formula (b-1). As the compound providing the structural unit (B-1), a compound represented by formula (b-1) (ie, diamine) is preferable.

The diamine component contains 70 mol% or more of the compound that provides the structural unit (B-1). The diamine component preferably contains 75 mol% or more, more preferably 80 mol% or more of the compound that provides the structural unit (B-1). The upper limit of the content ratio of the compound providing the structural unit (B-1) may be 90 mol%, 95 mol%, 99 mol%, or 100 mol%. The diamine component may consist only of the compound that provides the structural unit (B-1).

The diamine component may contain a compound other than the compound providing the structural unit (B-1), and such compounds include the above-mentioned aromatic diamines, alicyclic diamines, aliphatic diamines, and derivatives thereof (diisocyanates, etc.) can be mentioned.
The number of compounds optionally included in the diamine component (ie, compounds other than the compound providing the structural unit (B-1)) may be one or two or more.

Compounds optionally included in the diamine component include compounds that provide the structural unit (B-2) (i.e., compounds that provide the structural unit (B-2-1), compounds that provide the structural unit (B-2-2), At least one compound selected from the group consisting of a compound that provides the structural unit (B-2-3) and a compound that provides the structural unit (B-2-4) is preferred; ) is more preferred.
Examples of the compound that provides the structural unit (B-2) include a compound represented by formula (b-2-1), a compound represented by formula (b-2-2), and a compound represented by formula (b-2-3). Examples include the compound represented by the above formula and the compound represented by the formula (b-2-4), but the invention is not limited thereto, and derivatives thereof may be used as long as they can form the same structural unit. Examples of such derivatives include diisocyanates corresponding to diamines represented by formulas (b-2-1) to (b-2-4). As the compound that provides the structural unit (B-2), compounds represented by formulas (b-2-1) to (b-2-4) (ie, diamines) are preferred.

When the diamine component contains a compound that provides the structural unit (B-1) and a compound that provides the structural unit (B-2), the diamine component preferably contains the compound that provides the structural unit (B-1) in an amount of 70 to 95 mol%. Contains, more preferably 75 to 95 mol%, still more preferably 75 to 90 mol%, preferably 5 to 30 mol% of the compound providing the structural unit (B-2), more preferably 5 to 25 mol%. more preferably 10 to 25 mol%.
The diamine component preferably contains a total of 75 mol% or more, more preferably 80 mol% or more, and still more preferably 90 mol% or more of the compound that provides the structural unit (B-1) and the compound that provides the structural unit (B-2). It contains mol % or more, particularly preferably 99 mol % or more. The upper limit of the total content ratio of the compound providing the structural unit (B-1) and the compound providing the structural unit (B-2) is not particularly limited, ie, 100 mol%. The diamine component may consist only of a compound that provides the structural unit (B-1) and a compound that provides the structural unit (B-2).

The compound that provides the structural unit (B-2) may be only the compound that provides the structural unit (B-2-1), or may be the only compound that provides the structural unit (B-2-2), It may be only the compound that provides the structural unit (B-2-3), or it may be only the compound that provides the structural unit (B-2-4).
Furthermore, the compound that provides the structural unit (B-2) is a combination of two or more compounds selected from the group consisting of compounds that provide the structural units (B-2-1) to (B-2-4). Good too.

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

Furthermore, in the present invention, in addition to the above-mentioned tetracarboxylic acid component and diamine component, a terminal capping agent may be used in the production of the polyimide resin. As the terminal capping agent, monoamines or dicarboxylic acids are preferable. The amount of the terminal capping agent to be introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, per 1 mol of the tetracarboxylic acid component. Examples of monoamine terminal capping agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3- Ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. are recommended. Among these, benzylamine and aniline can be preferably used. As the dicarboxylic acid terminal capping agent, dicarboxylic acids are preferred, and a portion thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1 , 2-dicarboxylic acid, etc. are recommended. Among these, phthalic acid and phthalic anhydride can be preferably used.

There is no particular restriction on the method of reacting the above-mentioned tetracarboxylic acid component and diamine component, and any known method can be used.
As a specific reaction method, (1) a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, stirred at room temperature (approximately 20°C) to 80°C for 0.5 to 30 hours, and then heated to an elevated temperature. (2) After charging the diamine component and reaction solvent into a reactor and dissolving them, charging the tetracarboxylic acid component and heating at room temperature (approximately 20°C) to 80°C as necessary. A method of stirring for 0.5 to 30 hours and then raising the temperature to carry out the imidization reaction. (3) A method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor, and the temperature is immediately raised to carry out the imidization reaction. Examples include methods for performing this.

The reaction solvent used for producing the polyimide resin may be any solvent as long as it does not inhibit the imidization reaction and can dissolve the polyimide produced. Examples include aprotic solvents, phenolic solvents, ether solvents, carbonate solvents, and the like.

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

Specific examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4 -xylenol, 3,5-xylenol, etc.
Specific examples of ether solvents 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.
Further, specific examples of carbonate-based solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and the like.
Among the above reaction solvents, amide solvents or lactone solvents are preferred. Further, the above reaction solvents may be used alone or in combination of two or more.

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

In the above imidization reaction, a known imidization catalyst can be used. Examples of imidization catalysts include base catalysts and acid catalysts.
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 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 hydrogen carbonate, and sodium hydrogen carbonate.
In addition, examples of acid catalysts include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. can be mentioned. The above imidization catalysts may be used alone or in combination of two or more.
Among the above, from the viewpoint of ease of handling, it is preferable to use a base catalyst, it is more preferable to use an organic base catalyst, it is even more preferable to use triethylamine, and it is particularly preferable to use 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 reaction rate and suppression of gelation and the like. Further, the reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

[Polyimide varnish]
The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin of the present invention and an organic solvent, and the polyimide resin is dissolved in the organic solvent.
The organic solvent is not particularly limited as long as it dissolves the polyimide resin, but it is preferable to use the above-mentioned compounds alone or in a mixture of two or more types as a reaction solvent used in the production of the polyimide resin.
The polyimide varnish of the present invention may be a polyimide solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or it may be a polyimide solution obtained by adding a diluting solvent to the polyimide solution.

Since the polyimide resin of the present invention has solvent solubility, it can be made into a highly concentrated varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass, more preferably 10 to 30% by mass of the polyimide resin of the present invention. 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.
In addition, the polyimide varnish of the present invention may contain inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, antifoaming agents, fluorescent enhancers, etc. within the range that does not impair the required properties of the polyimide film. It may contain various additives such as a whitening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer.
The method for producing the polyimide varnish of the present invention is not particularly limited, and known methods can be applied.

[Polyimide film]
The polyimide film of the present invention contains the polyimide resin of the present invention. Therefore, the polyimide film of the present invention has excellent colorless transparency, optical isotropy, and chemical resistance (solvent resistance, acid resistance, and alkali resistance). The preferred physical properties of the polyimide film of the present invention are as described above.
There are no particular limitations on the method for producing the polyimide film of the present invention, and known methods can be used. For example, after the polyimide varnish of the present invention is coated on a smooth support such as a glass plate, metal plate, or plastic, or formed into a film, organic solvents such as reaction solvents and diluting solvents contained in the varnish are removed. Examples include a method of removing by heating.

Examples of the coating method include known coating methods such as spin coating, slit coating, and blade coating. Among these, slit coating is preferable from the viewpoint of controlling intermolecular orientation, improving chemical resistance, and workability.
The method for removing the organic solvent contained in the varnish by heating is to evaporate the organic solvent at a temperature of 150°C or lower to make it tack-free, and then heat the varnish to a temperature higher than the boiling point of the organic solvent used (although not particularly limited). It is preferable to dry at a temperature of 200 to 500°C. Moreover, it is preferable to dry under an air atmosphere or a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced pressure, normal pressure, or increased pressure.
The method for peeling off the polyimide film formed on the support is not particularly limited, but includes a laser lift-off method, a method using a sacrificial layer for peeling (preliminary coating of a release agent on the surface of the support), and a method using a sacrificial layer for peeling. method).

Moreover, the polyimide film of the present invention can also be manufactured using a polyamic acid varnish formed by dissolving polyamic acid in an organic solvent.
The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, and includes a compound that provides the above-mentioned structural unit (A-1) and a compound that provides the above-mentioned structural unit (A-2). It is a product of a polyaddition reaction between a tetracarboxylic acid component and a diamine component containing 70 mol% or more of the compound that provides the above-mentioned structural unit (B-1). By imidizing this polyamic acid (dehydration ring closure), the final product, the polyimide resin of the present invention, is obtained.
As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.
In the present invention, the polyamic acid varnish may be a polyamic acid solution itself obtained by polyaddition reaction of a tetracarboxylic acid component and a diamine component in a reaction solvent, or it may be further diluted with respect to the polyamic acid solution. A solvent may be added.

There are no particular limitations on the method for producing a polyimide film using polyamic acid varnish, and any known method can be used. For example, a polyamic acid varnish is applied onto a smooth support such as a glass plate, metal plate, or plastic, or formed into a film, and organic solvents such as reaction solvents and diluting solvents contained in the varnish are removed by heating. A polyimide film can be produced by obtaining a polyamic acid film and imidizing the polyamic acid in the polyamic acid film by heating.
The heating temperature when drying the polyamic acid varnish to obtain a polyamic acid film is preferably 50 to 120°C. The heating temperature when polyamic acid is imidized by heating is preferably 200 to 400°C.
Note that the imidization method is not limited to thermal imidization, and chemical imidization can also be applied.

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 still more preferably 10 to 80 μm. A thickness of 1 to 250 μm allows practical use as a self-supporting membrane.
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 suitably used as a substrate for image display devices such as liquid crystal displays and OLED displays.

The present invention will be specifically explained below using Examples. However, the present invention is not limited to these Examples in any way.

In Examples and Comparative Examples, each physical property was measured by the method shown below.
(1) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd.
(2) Tensile strength and tensile modulus Tensile strength and tensile modulus were measured using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127:1999. The distance between chucks was 50 mm, the test piece size was 10 mm x 70 mm, and the test speed was 20 mm/min.
(3) Glass transition temperature (Tg)
Using a thermomechanical analyzer "TMA/SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., remove residual stress in tensile mode under the conditions of sample size 2 mm x 20 mm, load 0.1 N, and temperature increase rate 10 ° C / min. The temperature was raised to a temperature sufficient to remove residual stress, and then cooled to room temperature. Thereafter, the elongation of the test piece was measured under the same conditions as the treatment for removing residual stress, and the point where the inflection point of elongation was found was determined as the glass transition temperature.
(4) Total light transmittance, yellow index (YI), b ^*
The total light transmittance, YI and b ^* were measured in accordance with JIS K7105:1981 using a simultaneous color and turbidity meter "COH400" manufactured by Nippon Denshoku Industries Co., Ltd.
(5) Thickness phase difference (Rth)
The thickness retardation (Rth) was measured using an ellipsometer "M-220" manufactured by JASCO Corporation. The value of the thickness retardation was measured at a measurement wavelength of 590 nm. Note that Rth is expressed by the following formula, where 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 something that
Rth=[{(nx+ny)/2}-nz]×d
(6) Solvent resistance A solvent was dropped at room temperature onto a polyimide film formed on a glass plate, and it was confirmed whether there was any change in the film surface. Note that propylene glycol monomethyl ether acetate (PGMEA) was used as the solvent.
The evaluation criteria for solvent resistance were as follows.
A: There was no change in the film surface.
B: Slight cracks appeared on the film surface.
C: Cracks appeared on the film surface or the film surface was dissolved.
(7) Acid resistance (mixed acid ΔYI and mixed acid Δb ^* )
A polyimide film formed on a glass plate was heated to 40°C and mixed with 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)). After being immersed in a mixed solution for 4 minutes, it was washed with water. After washing with water, the moisture was wiped off, and the sample was heated on a hot plate at 240° C. for 50 minutes to dry. YI and b ^* were measured before and after the test, and the changes (ΔYI and Δb ^* ) were determined. Note that the YI measurement and b ^* measurement here were performed in a state in which a polyimide film was formed on a glass plate (a state of glass plate + polyimide film).
(8) Alkali resistance A polyimide film formed on a glass plate was immersed in a potassium hydroxide aqueous solution having a concentration of 3% by mass at room temperature for 5 minutes, and then washed with water. After washing with water, it was confirmed whether there was any change in the film surface.
The evaluation criteria for alkali resistance were as follows.
A: There was no change in the film surface.
B: Slight cracks appeared on the film surface.
C: Cracks appeared on the film surface or the film surface was dissolved.

The tetracarboxylic acid component and diamine component used in Examples and Comparative Examples, and their abbreviations are as follows.
<Tetracarboxylic acid component>
HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.; compound represented by formula (a-1))
ODPA: 4,4'-oxydiphthalic anhydride (manufactured by Manac Co., Ltd.; compound represented by formula (a-2))
<Diamine component>
3,3'-DDS: 3,3'-diaminodiphenylsulfone (manufactured by Seika Co., Ltd.; compound represented by formula (b-1))
6FODA: 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl ether (manufactured by ChinaTech Chemical (Tianjin) Co., Ltd.; compound represented by formula (b-2-1))
BAFL: 9,9-bis(4-aminophenyl)fluorene (manufactured by Taoka Chemical Co., Ltd.; compound represented by formula (b-2-2))
HFBAPP: 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (manufactured by Seika Co., Ltd.; compound represented by formula (b-2-3))
TFMB: 2,2'-bis(trifluoromethyl)benzidine (manufactured by Seika Co., Ltd.; compound represented by formula (b-2-4))

<Example 1>
32.841 g of 3,3'-DDS (32.841 g) was placed in a 300 mL 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark fitted with a cooling tube, a thermometer, and a glass end cap. 0.132 mol) and 63.328 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the mixture was stirred at a rotational speed of 200 rpm at a system temperature of 70° C. under a nitrogen atmosphere to obtain a solution.
To this solution, 23.720 g (0.106 mol) of HPMDA, 8.206 g (0.026 mol) of ODPA, and 15.832 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. Thereafter, 0.669 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst, 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 reaction system was refluxed for about 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 160.841 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after the temperature inside the reaction system was cooled to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 1.

<Example 2>
31.073 g of 3,3'-DDS (31.073 g) was placed in a 300 mL 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark equipped with a cooling tube, a thermometer, and a glass end cap. 0.125 mol) and 63.077 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the mixture was stirred at a rotation speed of 200 rpm at a system temperature of 70° C. under a nitrogen atmosphere to obtain a solution.
To this solution, 14.027 g (0.063 mol) of HPMDA, 19.410 g (0.063 mol) of ODPA, and 15.769 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. Thereafter, 0.633 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for about 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 161.154 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 1.

<Example 3>
29.486 g of 3,3′-DDS ( 0.119 mol) and 62.851 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added and stirred at a rotational speed of 200 rpm at a system temperature of 70° C. and a nitrogen atmosphere to obtain a solution.
To this solution, 5.324 g (0.024 mol) of HPMDA, 29.470 g (0.095 mol) of ODPA, and 15.713 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. Thereafter, 0.601 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst, 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 reaction system was refluxed for about 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.436 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after the temperature inside the reaction system was cooled to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 1.

<Comparative example 1>
34.192 g of 3,3'-DDS (34.192 g) was placed in a 300 mL 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean Stark with a condenser tube, a thermometer, and a glass end cap. 0.137 mol) and 63.495 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the mixture was stirred at a rotation speed of 200 rpm at a system temperature of 70° C. under a nitrogen atmosphere to obtain a solution.
To this solution, 30.746 g (0.0137 mol) of HPMDA and 15.874 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was added as an imidization catalyst. ), heated with a mantle heater, maintained the reaction system internal temperature at 190° C. over about 20 minutes, and refluxed for about 5 hours.
Thereafter, 160.631 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 1.

<Comparative example 2>
28.588 g of 3,3′-DDS ( 0.115 mol) and 62.704 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the mixture was stirred at a rotational speed of 200 rpm at a system temperature of 70° C. under a nitrogen atmosphere to obtain a solution.
To this solution, 35.541 g (0.115 mol) of ODPA and 15.676 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was added as an imidization catalyst. ) 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 reaction system was refluxed for about 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 161.620g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the reaction system internal temperature to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 1.

<Comparative example 3>
36.092 g (0.103 mol) of BAFL was placed in a 300 mL 5-necked round-bottomed 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. and 63.309 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added and stirred at a rotation speed of 200 rpm at a system temperature of 70° C. and a nitrogen atmosphere to obtain a solution.
To this solution, 11.598 g (0.052 mol) of HPMDA, 16.035 g (0.052 mol) of ODPA, and 15.577 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. Thereafter, 0.523 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for about 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 162.113g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 1.

<Example 4>
25.353 g of 3,3'-DDS ( 0.102 mol), 8.547 g (0.025 mol) of 6FODA, and 63.142 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 22.797 g (0.102 mol) of HPMDA, 7.880 g (0.025 mol) of ODPA, and 15.785 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.643 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 161.073g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 5>
24.042 g of 3,3'-DDS ( 0.096 mol), 8.106 g (0.024 mol) of 6FODA, and 62.910 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 13.512 g (0.060 mol) of HPMDA, 18.681 g (0.060 mol) of ODPA, and 15.728 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.609 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.362 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid concentration of 20% by mass, and after cooling the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 6>
25.822 g of 3,3′-DDS ( 0.103 mol), 8.706 g (0.026 mol) of 6FODA, and 63.225 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 26.121 g (0.116 mol) of HPMDA, 4.013 g (0.013 mol) of ODPA, and 15.806 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.654 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 160.969 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 7>
25.218 g of 3,3'-DDS (25.218 g) was placed in a 300 mL five-necked round-bottomed 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. 0.101 mol), 8.821 g (0.025 mol) of BAFL, and 63.118 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 22.676 g (0.101 mol) of HPMDA, 7.838 g (0.025 mol) of ODPA, and 15.780 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.639 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 161.102g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 8>
23.921 g of 3,3'-DDS ( 0.096 mol), 8.367 g (0.024 mol) of BAFL, and 62.889 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 13.444 g (0.060 mol) of HPMDA, 18.587 g (0.060 mol) of ODPA, and 15.722 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.606 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.389 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system temperature to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 9>
Add 23.530 g of 3,3'-DDS ( 0.094 mol), 12.247 g (0.024 mol) of HFBAPP, and 62.820 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 21.158 g (0.094 mol) of HPMDA, 7.313 g (0.024 mol) of ODPA, and 15.705 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.596 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.475 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 10>
22.397 g of 3,3'-DDS (22.397 g) was placed in a 300 mL 5-necked round-bottomed 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. 0.090 mol), 11.657 g (0.022 mol) of HFBAPP, and 62.620 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 12.587 g (0.056 mol) of HPMDA, 17.402 g (0.056 mol) of ODPA, and 15.655 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.568 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst, 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.725 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system temperature to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 11>
23.933 g of 3,3′-DDS ( 0.096 mol), 12.457 g (0.024 mol) of HFBAPP, and 62.891 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 24.211 g (0.108 mol) of HPMDA, 3.719 g (0.012 mol) of ODPA, and 15.723 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.607 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 161.386g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Example 12>
26.000 g of 3,3'-DDS was placed in a 300 mL five-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean-Stark fitted with a cooling tube, a thermometer, and a glass end cap. 0.104 mol), 8.351 g (0.026 mol) of TFMB, and 63.256 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 26.302 g (0.117 mol) of HPMDA, 4.041 g (0.013 mol) of ODPA, and 15.814 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.659 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
After that, 160.930g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system temperature to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Comparative example 4>
15.356 g of 3,3'-DDS ( 0.062 mol), 21.485 g (0.062 mol) of BAFL, and 63.004 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 27.594 g (0.123 mol) of HPMDA and 15.751 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was added as an imidization catalyst. ) 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.246 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Comparative example 5>
13.053 g of 3,3'-DDS ( 0.052 mol), 18.263 g (0.052 mol) of BAFL, and 62.353 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 32.455 g (0.105 mol) of ODPA and 15.588 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added at once, and then triethylamine (manufactured by Kanto Chemical Co., Ltd.) was added as an imidization catalyst. ) 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 162.059 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% by mass, and after cooling the temperature inside the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

<Comparative example 6>
14.109 g of 3,3'-DDS ( 0.057 mol), 19.740 g (0.057 mol) of BAFL, and 62.651 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the system temperature was 70°C and the rotation speed was 200 rpm under a nitrogen atmosphere. A solution was obtained by stirring.
To this solution, 12.687 g (0.057 mol) of HPMDA, 17.540 g (0.057 mol) of ODPA, and 15.663 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added all at once. After that, 0.572 g of triethylamine (manufactured by Kanto Kagaku Co., Ltd.) was added as an imidization catalyst 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 reaction system was refluxed for 5 hours while the internal temperature of the reaction system was maintained at 190° C. while adjusting the rotation speed according to the increase in viscosity.
Thereafter, 161.686 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added to give a solid content concentration of 20% by mass, and after cooling the reaction system to 100°C, the mixture was further stirred for about 1 hour to ensure uniformity. Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held at 80 °C for 20 minutes on a hot plate, and then heated at 260 °C for 30 minutes in a hot air dryer in an air atmosphere to evaporate the solvent. A film was obtained. The results are shown in Table 2.

In addition, when the film of Comparative Example 1 was immersed in a mixed acid in an acid resistance test, it deteriorated significantly, so that YI and b ^* could not be measured after immersion. Therefore, ΔYI and Δb ^* of Comparative Example 1 could not be determined.

As shown in Table 1, the polyimide films of Examples 1 to 3 were produced using a combination of HPMDA and ODPA as the tetracarboxylic acid component and 3,3'-DDS as the diamine component. As a result, it was excellent in colorless transparency, optical isotropy, and chemical resistance (solvent resistance, acid resistance, and alkali resistance).
On the other hand, the polyimide film of Comparative Example 1 was manufactured using only HPMDA as the tetracarboxylic acid component. As a result, acid resistance was poor.
The polyimide film of Comparative Example 2 was produced using only ODPA as the tetracarboxylic acid component. As a result, colorless transparency and optical isotropy were poor.
The polyimide film of Comparative Example 3 was produced using only BAFL without using 3,3'-DDS as a diamine component. As a result, acid resistance was poor.

Furthermore, as shown in Table 2, the polyimide films of Examples 4 to 12 used not only 3,3'-DDS but also other secondary diamines (6FODA, BAFL, HFBAPP, or TFMB) as the diamine component. Manufactured by However, 3,3'-DDS and secondary diamine were used together so that the ratio of 3,3'-DDS was 70 mol% or more. As a result, it was excellent in colorless transparency, optical isotropy, and chemical resistance (solvent resistance, acid resistance, and alkali resistance).
On the other hand, the polyimide film of Comparative Example 4 was manufactured using 3,3'-DDS and other secondary diamine (BAFL) as diamine components, but the ratio of 3,3'-DDS used was 70. It was less than mol%. Furthermore, only HPMDA was used as the tetracarboxylic acid component. As a result, acid resistance was poor.
The polyimide film of Comparative Example 5 was produced using 3,3'-DDS and other secondary diamine (BAFL) as diamine components in combination, but the ratio of 3,3'-DDS used was 70 mol%. It was less than Furthermore, only ODPA was used as the tetracarboxylic acid component. As a result, colorless transparency (total light transmittance), optical isotropy, and acid resistance were poor.
The polyimide film of Comparative Example 6 was produced using 3,3'-DDS and other secondary diamine (BAFL) as the diamine component, but the ratio of 3,3'-DDS used was 70 mol%. It was less than As a result, optical isotropy and acid resistance were poor.

Claims (4)

A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine,
A structural unit (A-1) in which structural unit A is derived from a compound represented by the following formula (a-1), and a structural unit (A-2) derived from a compound represented by the following formula (a-2) including
The structural unit B consists only of the structural unit (B-1) derived from the compound represented by the following formula (b-1), or a structure other than the structural unit (B-1) and the structural unit (B-1) including units ,
The structural unit other than the structural unit (B-1) is a structural unit (B-2-1) derived from a compound represented by the following formula (b-2-1), a structural unit (B-2-1) derived from the following formula (b-2-2), A structural unit (B-2-2) derived from the compound represented by the following formula (B-2-3), a structural unit (B-2-3) derived from the compound represented by the following formula (b-2-3), and the structural unit (B-2-3) derived from the compound represented by the following formula (b- The structural unit (B-2) is at least one selected from the group consisting of the structural unit (B-2-4) derived from the compound represented by 2-4),
A polyimide resin in which the ratio of the structural unit (B-1) in the structural unit B is 70 to 95 mol% when the structural unit B contains a structural unit other than the structural unit (B-1).


(In formula (b-2-2), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.) The ratio of the structural unit (A-1) in the structural unit A is 5 to 95 mol%,
The polyimide resin according to claim 1, wherein the ratio of the structural unit (A-2) in the structural unit A is 5 to 95 mol%. A polyimide varnish obtained by dissolving the polyimide resin according to claim 1 or 2 in an organic solvent. A polyimide film comprising the polyimide resin according to claim 1 or 2.