KR20220034059A - Polyimide resins, polyimide varnishes and polyimide films - Google Patents

Abstract

A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine, wherein the structural unit A is a structural unit derived from a compound represented by the following formula (a-1) (A-1) ), and without the structural unit (A-2) derived from the compound represented by the following formula (a-2), the structural unit B is derived from the compound represented by the following formula (b-1) The ratio of the structural unit (B-1) in the structural unit B including the structural unit (B-1) and the structural unit (B-2) derived from the compound represented by the following formula (b-2) The polyimide resin is 30 to 70 mol%, and the proportion of the structural unit (B-2) in the structural unit B is 70 to 30 mol%.

Description

Polyimide resins, polyimide varnishes and polyimide films

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

Various uses of polyimide resin are considered in the field|area, such as an electric/electronic component. For example, it is desired to replace a glass substrate used in an image display device such as a liquid crystal display or an OLED display with a plastic substrate for the purpose of weight reduction or flexibility of the device, and a polyimide film suitable as the plastic substrate research is in progress.

In an image display device, when light emitted from a display element is emitted through a plastic substrate, colorless transparency is required for the plastic substrate, and further, when light passes through a retardation film or a polarizing plate (for example, a liquid crystal display , touch panel, etc.) is required to have high optical isotropy (that is, low Rth) in addition to colorless transparency.

In order to satisfy the performance requirements as described above, various polyimide resins are being developed. For example, in Patent Document 1, 3,3'-diaminodiphenylsulfone (1st diamine) and 4,4 as a polyimide resin that provides a colorless, transparent, low Rth and excellent toughness polyimide film. A polyimide resin prepared by using a combination of a specific diamine (second diamine) such as '-diaminodiphenylsulfone as a diamine component is described.

In addition, in Patent Document 2, the applicant is a polyimide resin having a high refractive index, and as a dicarboxylic acid component, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 3,3',4,4'- A polyimide using a combination of biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenylsulfone and bis[4-(4-aminophenoxy)phenyl]sulfone as diamines in combination is disclosed. .

International Publication No. 2016/158825 International Publication No. 2017/195574

By the way, in order for a polyimide film to be suitable as a board|substrate, not only colorless transparency and optical isotropy but also chemical-resistance (for example, acid resistance and alkali resistance) are important physical properties.

For example, when a polyimide film is used as a board|substrate for ITO (Indium Tin Oxide) film formation, resistance with respect to the acid used for the etching of an ITO film is calculated|required by the polyimide film. When the acid resistance of the polyimide film is insufficient, the film may yellow and colorless and transparent may be impaired.

In addition, alkaline aqueous solutions, such as sodium hydroxide aqueous solution and potassium hydroxide aqueous solution, are mainly used for washing|cleaning of supports (a support body to which polyimide varnish is applied), such as a glass plate, used when manufacturing a polyimide film. Washing with an alkaline aqueous solution may be performed even in the state in which the polyimide film was formed into a film on support bodies, such as a glass plate. Therefore, resistance to alkali is also required for the polyimide film.

However, in Patent Document 1, chemical resistance was not evaluated.

In addition, when a polyimide film is used as a substrate, a desired electronic circuit is made on the polyimide film through various processes such as a sputtering process or an etching process for forming a metal film depending on the use. During this time, the polyimide film is If it is not closely_contact|adhered on support bodies, such as a glass plate, a problem will arise in a process. Moreover, the process of peeling a polyimide film from a support body after these processes is needed. In that case, the polyimide film is required to have good elongation while having constant toughness, ie, high strength, in the sense of facilitating the process and preventing breakage during peeling.

In addition, in manufacturing polyimide, various monomers are combined, but depending on the type of the monomer, the reactivity is poor, and when trying to increase the molecular weight of the polyimide, the polymerization takes an excessive time. shortening was desired.

The present invention has been made in view of this situation, and the object of the present invention is to form a film excellent in colorless transparency, optical isotropy, chemical resistance (eg, acid resistance and alkali resistance), and toughness, and polymerization time is short. It is to provide a short polyimide resin, and a polyimide varnish and polyimide film comprising the polyimide resin.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that the said subject could be solved by the polyimide resin containing the combination of specific structural unit, and came to complete invention.

That is, the present invention relates to the following [1] to [3].

[1] A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,

The structural unit A includes a structural unit (A-1) derived from a compound represented by the following formula (a-1), and a structural unit derived from a compound represented by the following formula (a-2) (A- 2) not including;

The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1) and a structural unit (B-2) derived from a compound represented by the following formula (b-2) and,

The polyimide resin wherein the proportion of the structural unit (B-1) in the structural unit B is 30 to 70 mol%, and the proportion of the structural unit (B-2) in the structural unit B is 70 to 30 mol%.

[Formula 1]

[2] A polyimide varnish obtained by dissolving the polyimide resin according to [1] above in an organic solvent.

[3] A polyimide film comprising the polyimide resin according to [1] above.

According to the present invention, a film having excellent colorless transparency, optical isotropy, chemical resistance (eg, acid resistance and alkali resistance), and toughness can be formed, and the polymerization time of the polyimide resin is short.

[Polyimide resin]

The polyimide resin of the present invention has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine, and the structural unit A is a structural unit derived from a compound represented by the following formula (a-1) Including (A-1), and without the structural unit (A-2) derived from the compound represented by the following formula (a-2), the structural unit B is represented by the following formula (b-1) The structural unit (B-1) derived from the compound used and the structural unit (B-2) derived from the compound represented by the following formula (b-2) are included. And the ratio of the structural unit (B-1) in the structural unit B is 30-70 mol%, and the ratio of the structural unit (B-2) in the structural unit B is 70-30 mol%.

[Formula 2]

<composition unit A>

The structural unit A is a structural unit derived from tetracarboxylic dianhydride in the polyimide resin, and includes a structural unit (A-1) derived from a compound represented by the following formula (a-1), and The structural unit (A-2) derived from the compound represented by Formula (a-2) is not included.

[Formula 3]

The compound represented by formula (a-1) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

When the structural unit A includes the structural unit (A-1), colorless transparency, optical isotropy, and chemical resistance of the film can be improved.

The compound represented by formula (a-2) is 4,4'-oxydiphthalic anhydride. When the structural unit A does not contain the structural unit (A-2), the polymerization time of the polyimide resin can be shortened.

The proportion of the structural unit (A-1) in the structural unit A is preferably 90 mol% or more, more preferably more than 95 mol%, still more preferably 97 mol% or more, particularly preferably 100 mol% or more. am. That is, it is particularly preferable that the structural unit A consists only of the structural unit (A-1).

The structural unit A may include structural units other than the structural unit (A-1). The tetracarboxylic dianhydride giving such a structural unit is not particularly limited, but pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 9,9'-bis( Aromatic tetracarboxylic dianhydrides such as 3,4-dicarboxyphenyl)fluorene dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (provided that they are represented by formula (a-2) compounds are excluded); 1,2,3,4-Cyclobutanetetracarboxylic dianhydride and norbornane-2-spiro-α-cyclopentanone-α′-spiro-2′′-novonane-5,5′′,6,6 alicyclic tetracarboxylic dianhydride such as ''-tetracarboxylic dianhydride (however, the compound represented by the formula (a-1) is excluded); and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride.

On the other hand, in the present specification, aromatic tetracarboxylic dianhydride means tetracarboxylic dianhydride containing one or more aromatic rings, and alicyclic tetracarboxylic dianhydride includes one or more alicyclic rings and also aromatic rings. It means tetracarboxylic dianhydride not containing, and aliphatic tetracarboxylic dianhydride means tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.

The structural unit arbitrarily included in the structural unit A may be one type, or two or more types may be sufficient as it.

<Composition B>

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

[Formula 4]

The compound represented by the formula (b-1) is 3,3'-diaminodiphenylsulfone.

When the structural unit B includes the structural unit (B-1), the optical isotropy and chemical resistance of the film can be improved.

The compound represented by formula (b-2) is bis[4-(4-aminophenoxy)phenyl]sulfone.

When the structural unit B includes the structural unit (B-2), the toughness of the film, that is, the tensile elongation can be improved.

The proportion of the structural unit (B-1) in the structural unit B is 30 to 70 mol%, preferably 40 to 65 mol%, and more preferably 50 to 60 mol%. When the ratio of the structural unit (B-1) in the structural unit B is within the range, the polymerization time of the polyimide resin is relatively short, which is preferable.

The proportion of the structural unit (B-2) in the structural unit B is 70 to 30 mol%, preferably 60 to 35 mol%, and more preferably 50 to 40 mol%. When the ratio of the structural unit (B-2) in the structural unit B is within the range, the polymerization time of the polyimide resin is relatively short, which is preferable.

The molar ratio [(B-1)/(B-2)] of the structural unit (B-1) to the structural unit (B-2) in the structural unit B is preferably 30/70 to 70/30. , More preferably, it is 40/60 - 65/35, More preferably, it is 50/50 - 60/40.

If the ratio or molar ratio of the structural unit (B-1) and the structural unit (B-2) is within the above range, the polymerization time can be shortened, and the transparency and toughness (modulus of elasticity, strength, and elongation) of the resulting polyimide resin can be improved. can be improved

In particular, from the viewpoint of polymerization time, the molar ratio [(B-1)/(B-2)] of the structural unit (B-1) to the structural unit (B-2) in the structural unit B is preferably 50 It is /50-70/30, More preferably, it is 55/45-70/30, More preferably, it is 60/40-70/30.

In particular, from the viewpoint of toughness (strength and elongation) and transparency, the molar ratio [(B-1)/(B-2) of the structural unit (B-1) to the structural unit (B-2) in the structural unit B )] is preferably 30/70 to 60/40, more preferably 30/70 to 55/45, still more preferably 30/70 to 50/50.

The proportion of the total of the structural units (B-1) and (B-2) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more. % or more, particularly preferably 99 mol% or more. The upper limit of the ratio of the sum total of structural units (B-1) and (B-2) is not specifically limited, That is, it is 100 mol%. The structural unit B may consist of only the structural unit (B-1) and the structural unit (B-2).

The structural unit B may include structural units other than the structural units (B-1) and (B-2). Although it does not specifically limit as a diamine giving such a structural unit, 1, 4- phenylenediamine, p-xylylene diamine, 3, 5- diamino benzoic acid, 1, 5- diamino naphthalene, 2,2'- Dimethylbiphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2 -Bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminobenzanilide, 1-(4-aminophenyl)-2,3-dihydro- 1,3,3-trimethyl-1H-inden-5-amine, α,α′-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N′-bis(4-aminophenyl) Terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-(4-amino) Aromatic diamines such as phenoxy)phenyl)hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, and 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether (However, the compound represented by Formula (b-1) is excluded); alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; And aliphatic diamines, such as ethylenediamine and hexamethylenediamine, are mentioned.

On the other hand, in the present specification, aromatic diamine means diamine containing one or more aromatic rings, alicyclic diamine means diamine containing one or more alicyclic rings and does not contain an aromatic ring, and aliphatic diamine is It means diamine which contains neither an aromatic ring nor an alicyclic ring.

The structural unit arbitrarily included in the structural unit B may be one type, or two or more types may be sufficient as it.

Examples of the diamine that imparts the structural unit optionally included in the structural unit B include a compound represented by the following formula (b-3-1), a compound represented by the following formula (b-3-2), and a compound represented by the following formula (b-3) The compound represented by -3) and the compound represented by the following formula (b-3-4) are preferable. That is, in the polyimide resin of one embodiment of the present invention, the structural unit B is a structural unit derived from a compound represented by the following formula (b-3-1) (B-3-1), the following formula (b-3) A structural unit derived from a compound represented by -2) (B-3-2), a structural unit derived from a compound represented by the following formula (b-3-3) (B-3-3), and a structural unit derived from a compound represented by the following formula (b-3-3), and the following formula ( It may further contain the structural unit (B-3) which is at least 1 selected from the group which consists of structural units (B-3-4) derived from the compound represented by b-3-4).

[Formula 5]

(In formula (b-3-2), each R is independently a hydrogen atom, a fluorine atom, or a methyl group.)

The compound represented by formula (b-3-1) is 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether.

When the structural unit B includes the structural unit (B-3-1), colorless transparency of the film can be improved.

In the formula (b-3-2), each R is independently a hydrogen atom, a fluorine atom, or a methyl group, preferably a hydrogen atom. Examples of the compound represented by the formula (b-3-2) include 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, and 9 , 9-bis(3-methyl-4-aminophenyl)fluorene etc. are mentioned, 9,9-bis(4-aminophenyl)fluorene is preferable.

When the structural unit B includes the structural unit (B-3-2), the optical isotropy and heat resistance of the film can be improved.

The compound represented by the formula (b-3-3) is 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane.

When the structural unit B includes the structural unit (B-3-3), colorless transparency of the film can be improved.

The compound represented by formula (b-3-4) is 2,2'-bis(trifluoromethyl)benzidine.

When the structural unit B includes the structural unit (B-3-4), colorless transparency, chemical resistance, and mechanical properties of the film can be improved.

When the structural unit B includes the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3), the structural unit (B-1) and the structural unit ( The total ratio of B-2) is preferably 70 to 95 mol%, more preferably 75 to 95 mol%, still more preferably 75 to 90 mol%, and the structural unit in the structural unit B ( The ratio of B-3) becomes like this. Preferably it is 5-30 mol%, More preferably, it is 5-25 mol%, More preferably, it is 10-25 mol%.

The ratio of the total of the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3) in the structural unit B is preferably 75 mol% or more, more preferably 80 It is mol% or more, More preferably, it is 90 mol% or more, Especially preferably, it is 99 mol% or more. The upper limit of the ratio of the total of the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3) is not particularly limited, that is, it is 100 mol%. The structural unit B may consist only of the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3).

A structural unit (B-3) may be only a structural unit (B-3-1), may be only a structural unit (B-3-2), may be only a structural unit (B-3-3), or may be a structural unit (B-3-3). It may be only the unit (B-3-4).

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

The number average molecular weight of the polyimide resin of this invention becomes like this. From a viewpoint of the mechanical strength of the polyimide film obtained, Preferably it is 5,000-200,000. In addition, the number average molecular weight of a polyimide resin can be calculated|required from the standard polymethylmethacrylate (PMMA) conversion value by gel filtration chromatography measurement, for example.

The polyimide resin of the present invention may contain a structure other than the polyimide chain (a structure in which the structural unit A and the structural unit B are imide-bonded). As structures other than the polyimide chain which can be contained in polyimide resin, the structure etc. containing an amide bond are mentioned, for example.

The polyimide resin of the present invention preferably contains a polyimide chain (a structure in which the structural unit A and the structural unit B are imide-bonded) as a main structure. Therefore, the proportion of the polyimide chain in the polyimide resin of the present invention is preferably 50 mass % or more, more preferably 70 mass % or more, still more preferably 90 mass % or more, particularly preferably It is 99 mass % or more.

By using the polyimide resin of the present invention, it is possible to form a film excellent in colorless transparency, optical isotropy, chemical resistance (eg acid resistance and alkali resistance), and toughness, and the suitable physical property values of the film are as follows. .

When a total light transmittance is set as the film of 10 micrometers in thickness, Preferably it is 88 % or more, More preferably, it is 88.5 % or more, More preferably, it is 89 % or more.

The yellow index (YI) is preferably 4.0 or less, more preferably 2.5 or less, still more preferably 2.0 or less when a film having a thickness of 10 µm is obtained.

When b ^* is set as a film of 10 micrometers in thickness, Preferably it is 2.0 or less, More preferably, it is 1.2 or less, More preferably, it is 1.0 or less.

The absolute value of the thickness retardation Rth is preferably 70 nm or less, more preferably 60 nm or less, and still more preferably 35 nm or less when a film having a thickness of 10 µm is obtained. It is excellent in optical isotropy in it being this range.

The tensile strength is preferably 105 MPa or more, more preferably 110 MPa or more, and still more preferably 115 MPa or more. The tensile elongation is preferably 5 to 20%, more preferably 5 to 15%. When both the tensile strength and tensile elongation are within these ranges, the toughness of the film is excellent, the peeling becomes easy in the step of peeling the polyimide film from the support, and rupture during peeling can be prevented.

Mixed acid ΔYI is preferably 1.5 or less, more preferably 1.3 or less, still more preferably 1.0 or less when a film having a thickness of 10 µm is obtained.

Mixed acid Δb ^* is preferably 0.8 or less, more preferably 0.6 or less, and still more preferably 0.5 or less when a film having a thickness of 10 µm is obtained.

On the other hand, mixed acid ΔYI and mixed acid Δb ^* mean the difference between YI and b ^* before and after immersion when the polyimide film is immersed in a mixture of phosphoric acid, nitric acid and acetic acid, respectively, specifically, Examples It can be measured by the method described in It means that it is excellent in acid resistance, so that ΔYI and Δb ^* are small. By using the polyimide resin of this invention, the film excellent in chemical-resistance can be formed, and the outstanding resistance also to an acid is shown. In particular, it exhibits excellent resistance to the above acid mixture.

The film that can be formed by using the polyimide resin of the present invention has good mechanical properties and heat resistance, and has the following suitable physical properties.

The tensile modulus of elasticity is preferably 2.0 GPa or more, more preferably 2.5 GPa or more, and still more preferably 3.0 GPa or more.

The glass transition temperature (Tg) is preferably 250°C or higher, more preferably 270°C or higher, and still more preferably 300°C or higher. If it is this range, it has heat resistance suitable for manufacturing image display devices, such as a liquid crystal display and an OLED display, using a polyimide substrate.

In addition, the above-mentioned physical property value in this invention can be specifically measured by the method as described in an Example.

[Method for producing polyimide resin]

The polyimide resin of the present invention comprises a tetracarboxylic acid component containing a compound providing the above-mentioned structural unit (A-1) (however, the compound providing the above-mentioned structural unit (A-2) is not included) and , It can manufacture by making the diamine component containing the compound which provides the above-mentioned structural unit (B-1) and the compound which provides the above-mentioned structural unit (B-2) react.

Although the compound represented by Formula (a-1) is mentioned as a compound which provides a structural unit (A-1), It is not limited to it, It may be a derivative|guide_body in the range which gives the same structural unit. Examples of the derivative include tetracarboxylic acid corresponding to tetracarboxylic dianhydride represented by formula (a-1) (ie, 1,2,4,5-cyclohexanetetracarboxylic acid) and an alkyl ester of tetracarboxylic acid. can be heard As a compound which provides a structural unit (A-1), the compound (ie, a dianhydride) represented by Formula (a-1) is preferable.

The tetracarboxylic acid component preferably contains 90 mol% or more of the compound providing the structural unit (A-1), more preferably contains more than 95 mol%, and still more preferably 97 mol% or more. It contains, and more preferably contains 100 mol%.

The tetracarboxylic acid component may contain compounds other than the compound giving the structural unit (A-1), and examples of the compound include the aforementioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic. tetracarboxylic dianhydride and their derivatives (tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.) are mentioned.

The number of compounds arbitrarily contained in the tetracarboxylic acid component may be one, and two or more types may be sufficient as them.

Although the compound represented by formula (b-1) is mentioned as a compound which provides a structural unit (B-1), It is not limited to it, It may be a derivative|guide_body in the range which gives the same structural unit. As this derivative, the diisocyanate corresponding to the diamine represented by Formula (b-1) is mentioned. As a compound which provides a structural unit (B-1), the compound (ie, diamine) represented by Formula (b-1) is preferable.

Although the compound represented by Formula (b-2) is mentioned as a compound which provides a structural unit (B-2), It is not limited to it, It may be a derivative|guide_body within the range which gives the same structural unit. As this derivative, the diisocyanate corresponding to the diamine represented by Formula (b-2) is mentioned. As a compound which provides a structural unit (B-2), the compound (namely, diamine) represented by Formula (b-2) is preferable.

The diamine component contains preferably 30 to 70 mol% of the compound giving the structural unit (B-1), more preferably 40 to 65 mol%, and still more preferably 50 to 60 mol% do. If the ratio of the compound providing the structural unit (B-1) in the diamine component is within the range, the polymerization time of the polyimide resin is relatively short, which is preferable.

The diamine component contains preferably 70 to 30 mol%, more preferably 60 to 35 mol%, and still more preferably 50 to 40 mol% of the compound providing the structural unit (B-2). When the ratio of the compound providing the structural unit (B-2) in the diamine component is within the range, the polymerization time of the polyimide resin is relatively short, which is preferable.

The molar ratio [(B-1)/(B-2)] of the compound providing the structural unit (B-1) and the compound providing the structural unit (B-2) in the diamine component is preferably 30 It is /70-70/30, More preferably, it is 40/60-65/35, More preferably, it is 50/50-60/40.

In particular, from the viewpoint of polymerization time, the molar ratio of the compound providing the structural unit (B-1) to the compound providing the structural unit (B-2) in the diamine component [(B-1)/(B-2) ] is preferably 50/50 to 70/30, more preferably 55/45 to 70/30, still more preferably 60/40 to 70/30.

In particular, from the viewpoint of toughness (strength and elongation) and transparency, the molar ratio of the compound giving the structural unit (B-1) to the compound giving the structural unit (B-2) in the diamine component [(B- 1)/(B-2)] is preferably 30/70 to 60/40, more preferably 30/70 to 55/45, still more preferably 30/70 to 50/50.

The diamine component contains, in total, preferably 50 mol% or more, more preferably 70 mol% or more, of the compound giving the structural unit (B-1) and the compound giving the structural unit (B-2) , More preferably, it contains 90 mol% or more, Especially preferably, it contains 99 mol% or more. The upper limit of the content ratio of the total of the compound giving the structural unit (B-1) and the compound giving the structural unit (B-2) is not particularly limited, that is, it is 100 mol%. The diamine component may consist only of a compound providing the structural unit (B-1) and a compound providing the structural unit (B-2).

The diamine component may contain a compound other than the compound imparting the structural unit (B-1) or (B-2), and the compound includes the aforementioned aromatic diamine, alicyclic diamine, and aliphatic diamine, and derivatives thereof. (diisocyanate etc.) are mentioned.

The number of compounds (ie, compounds other than the compound which provides a structural unit (B-1) or (B-2)) contained arbitrarily in a diamine component may be one, or 2 or more types may be sufficient as it.

As a compound arbitrarily included in the diamine component, a compound giving a structural unit (B-3) (that is, a compound giving a structural unit (B-3-1), a compound giving a structural unit (B-3-2) at least one selected from the group consisting of a compound, a compound providing a structural unit (B-3-3), and a compound providing a structural unit (B-3-4)) is preferable.

Examples of the compound giving the structural unit (B-3) include a compound represented by the formula (b-3-1), a compound represented by the formula (b-3-2), and a compound represented by the formula (b-3-3) compound and the compound represented by formula (b-3-4), but is not limited thereto, and may be a derivative thereof within the range capable of forming the same structural unit. As this derivative, the diisocyanate corresponding to the diamine represented by a formula (b-3-1) - a formula (b-3-4) is mentioned. As the compound giving the structural unit (B-3), at least one selected from the group consisting of compounds represented by formulas (b-3-1) to (b-3-4) (ie, diamine) is desirable.

When a diamine component contains the compound which provides a structural unit (B-1), the compound which provides a structural unit (B-2), and the compound which provides a structural unit (B-3), a diamine component is a structural unit Preferably 70-95 mol% of the compound giving (B-1) and the compound giving structural unit (B-2) in total, More preferably, it contains 75-95 mol%, More preferably contains 75 to 90 mol%, preferably 5 to 30 mol% of the compound giving the structural unit (B-3), more preferably 5 to 25 mol%, further preferably 10 to 25 mol% is included.

A diamine component is a total of the compound which provides a structural unit (B-1), the compound which provides a structural unit (B-2), and the compound which provides a structural unit (B-3), Preferably 75 mol% More preferably, it contains 80 mol% or more, More preferably, it contains 90 mol% or more, Especially preferably, it contains 99 mol% or more. The upper limit of the content ratio of the total of the compound giving the structural unit (B-1), the compound giving the structural unit (B-2), and the compound giving the structural unit (B-3) is not particularly limited, namely , 100 mol%. The diamine component may consist only of a compound providing a structural unit (B-1), a compound providing a structural unit (B-2), and a compound providing a structural unit (B-3).

The compound providing the structural unit (B-3) may be only a compound providing the structural unit (B-3-1), or may be only a compound providing the structural unit (B-3-2), or the structural unit (B-3-2) It may be only the compound which provides B-3-3), or only the compound which provides the structural unit (B-3-4) may be sufficient.

Further, the compound providing the structural unit (B-3) may be a combination of two or more compounds selected from the group consisting of compounds giving the structural units (B-3-1) to (B-3-4). there is.

In the present invention, it is preferable that the input ratio of the tetracarboxylic acid component and the diamine component used in the production of the polyimide resin is 0.9 to 1.1 moles of the diamine component with respect to 1 mole of the tetracarboxylic acid component.

Further, in the present invention, for the production of the polyimide resin, in addition to the tetracarboxylic acid component and the diamine component described above, an end-blocking agent may be used. As the terminal blocker, monoamines or dicarboxylic acids are preferable. The amount of the terminal blocker to be introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. Monoamine end caps include, for example, 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 used suitably. As the dicarboxylic acid end capping agent, dicarboxylic acids are preferable, and a part thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid and the like are recommended. Among these, phthalic acid and phthalic anhydride can be used suitably.

There is no restriction|limiting in particular in the method of making the above-mentioned tetracarboxylic acid component and diamine component react, A well-known method can be used.

As a specific reaction method, (1) a method in which tetracarboxylic acid component, diamine component, and reaction solvent are put into a reactor, stirred at room temperature to 80° C. for 0.5 to 30 hours, and then the temperature is raised to perform imidization reaction, ( 2) After dissolving the diamine component and the reaction solvent in the reactor, the tetracarboxylic acid component is added, and if necessary, the mixture is stirred at room temperature to 80° C. for 0.5 to 30 hours, and then the temperature is raised to perform imidization reaction; (3) A method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are put into a reactor, and the temperature is immediately raised to perform imidization reaction; and the like.

The reaction solvent used for manufacture of a polyimide resin should just be what can melt|dissolve the polyimide resin produced|generated without inhibiting imidation reaction. For example, an aprotic solvent, a phenol type solvent, an ether type solvent, a carbonate type solvent, etc. are mentioned.

Specific examples of the aprotic solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, and 1,3-dimethylimidazoli. Amide solvents such as dinon and tetramethylurea, Lactone solvents such as γ-butyrolactone and γ-valerolactone, Phosphorus-containing amide solvents such as hexamethylphospholicamide and hexamethylphosphine triamide, dimethylsulfone , sulfur-containing solvents such as dimethyl sulfoxide and sulfolane, ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone, amine solvents such as picoline and pyridine, acetic acid (2-methoxy-1-methylethyl ) and the like ester solvents.

Specific examples of the phenolic solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6 -xylenol, 3,4-xylenol, 3,5-xylenol, etc. are mentioned.

Specific examples of the ether solvent include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methyl) ethoxy)ethyl]ether, tetrahydrofuran, 1,4-dioxane, and the like.

Further, specific examples of the carbonate-based solvent include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and the like.

Among the above reaction solvents, an amide-based solvent or a lactone-based solvent is preferable. In addition, the above reaction solvents may be used alone or in mixture of two or more.

In the imidation 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 operation, polymerization degree and imidation rate can be raised more.

In the above imidation reaction, a known imidation catalyst can be used. Examples of the imidization catalyst include a base catalyst or an acid catalyst.

Examples of the base catalyst include pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine , triethylenediamine, imidazole, N,N-dimethylaniline, N,N-diethylaniline, etc. organic base catalyst, potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, etc. inorganic base catalysts.

Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, paratoluenesulfonic acid, and naphthalenesulfonic acid. The above imidation catalysts may be used alone or in combination of two or more.

Among the above, from the viewpoint of handling properties, it is preferable to use a base catalyst, more preferably to use an organic base catalyst, still more preferably to use triethylamine, and particularly preferably to use a combination of triethylamine and triethylenediamine. Do.

The temperature of the imidation reaction is preferably 120 to 250°C, more preferably 160 to 200°C from the viewpoint of suppression of reaction rate and gelation. Further, the reaction time is preferably 0.5 to 6 hours, more preferably 0.5 to 5.5 hours after the start of outflow of the product water. The reaction time of the polyimide resin of the present invention is relatively short.

30-60 mass % is preferable, as for the solid content concentration at the time of imidation reaction, 35-58 mass % is more preferable, 40-56 mass % is especially preferable. When the solid content concentration during the imidization reaction is within this range, the imidation reaction proceeds favorably and water generated during the reaction is easily removed, so that the polymerization degree and the imidization rate can be increased.

However, the solid content concentration in the imidation reaction is a value calculated from the following formula based on the mass of the tetracarboxylic acid component added to the reaction system, the diamine component in the reaction system, and the reaction solvent.

Solid content concentration during imidization reaction (mass %) = (total mass of tetracarboxylic acid component and diamine component) / (total mass of tetracarboxylic acid component, diamine component, and reaction solvent) x 100

[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, and it is preferable to use the above-mentioned compounds alone or in mixture of two or more as the reaction solvent used for the production of the polyimide resin.

The polyimide varnish of the present invention may be a polyimide solution itself in which the polyimide resin obtained by polymerization is dissolved in a reaction solvent, or may be a polyimide solution further added with a diluting solvent.

Since the polyimide resin of this invention has solvent solubility, it can be set as the high concentration varnish which is stable at room temperature. It is preferable that 5-40 mass % of polyimide resins of this invention are included, and, as for the polyimide varnish of this invention, it is more preferable that 10-30 mass % is included. 1-200 Pa.s are preferable and, as for the viscosity of a polyimide varnish, 1.5-100 Pa.s are more preferable. The viscosity of a polyimide varnish is the value measured at 25 degreeC using the E-type viscometer.

In addition, the polyimide varnish of the present invention contains inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, surfactants, leveling agents, defoamers, optical brighteners, crosslinking agents, It may contain various additives, such as a polymerization initiator and a photosensitizer.

The manufacturing method of the polyimide varnish of this invention is not specifically limited, A well-known method is applicable.

[Polyimide Film]

The polyimide film of this invention contains the polyimide resin of this invention. Accordingly, the polyimide film of the present invention is excellent in colorless transparency, optical isotropy, and chemical resistance (eg, acid resistance and alkali resistance). Suitable physical property values of the polyimide film of the present invention are as described above.

There is no restriction|limiting in particular in the manufacturing method of the polyimide film of this invention, A well-known method can be used. For example, after the polyimide varnish of the present invention is coated on a smooth support such as a glass plate, a metal plate, or a plastic, or molded into a film, an organic solvent such as a reaction solvent or a diluent solvent contained in the varnish is heated and a method of removing it by

As a coating method, well-known coating methods, such as spin coating, slit coating, and blade coating, are mentioned. Especially, a slit coat is preferable from a viewpoint of workability|operativity that chemical-resistance improves by controlling an intermolecular orientation.

As a method of removing the organic solvent contained in the varnish by heating, after evaporating the organic solvent at a temperature of 150° C. or less to make it tack-free, the temperature above the boiling point of the used organic solvent (not particularly limited, but preferably 200 It is preferred to dry at ~500°C). In addition, it is preferable to dry under an air atmosphere or a nitrogen atmosphere. The pressure of the dry atmosphere may be any of reduced pressure, normal pressure, and pressurization.

The method of peeling the polyimide film formed on the support from the support is not particularly limited, but includes a laser lift-off method and a method using a sacrificial layer for peeling (a method of applying a release agent to the surface of the support in advance). there is.

Moreover, the polyimide film of this invention can also be manufactured using the polyamic-acid varnish in which polyamic acid is melt|dissolved in the organic solvent.

The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, comprising a compound providing the above-mentioned structural unit (A-1) and a compound providing the above-mentioned structural unit (A-2). It is a product of the polyaddition reaction of the tetracarboxylic acid component contained and the diamine component containing the compound giving the above-mentioned structural unit (B-1), and the compound giving the above-mentioned structural unit (B-2). By imidating this polyamic acid (ring closure by dehydration), the polyimide resin of the present invention as a final product is obtained.

As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention may 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 a polyamic acid solution obtained by adding a further diluting solvent to the polyamic acid solution. it may be

There is no restriction|limiting in particular in the method of manufacturing a polyimide film using a polyamic-acid varnish, A well-known method can be used. For example, a polyamic acid varnish is applied on a smooth support such as a glass plate, a metal plate, or a plastic, or is molded into a film, and an organic solvent such as a reaction solvent or a diluent solvent contained in the varnish is removed by heating. to obtain a polyamic acid film, and by imidizing the polyamic acid in the polyamic acid film by heating, a polyimide film can be produced.

The heating temperature for drying the polyamic acid varnish to obtain a polyamic acid film is preferably 50 to 120°C. As a heating temperature at the time of imidating polyamic acid by heating, Preferably it is 200-400 degreeC.

On the other hand, the imidation method is not limited to thermal imidization, and chemical imidization can also be applied.

Although the thickness of the polyimide film of this invention can be suitably selected according to a use etc., Preferably it is 1-250 micrometers, More preferably, it is 5-100 micrometers, More preferably, it is the range of 10-80 micrometers. Practical use as a self-supporting film becomes possible because thickness is 1-250 micrometers.

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 this invention is used suitably as a film for various members, such as a color filter, a flexible display, a semiconductor component, and an optical member. The polyimide film of this invention is used especially suitably as a board|substrate of image display apparatuses, such as a liquid crystal display and an OLED display.

Example

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

In an Example and a comparative example, each physical property was measured by the method shown below.

(1) Film thickness

The film thickness was measured using a micrometer manufactured by Mitsutoyo Co., Ltd.

(2) Tensile strength (tensile strength), tensile modulus of elasticity, tensile elongation (tensile deformation)

Tensile strength (tensile strength), tensile modulus of elasticity, and tensile elongation (tensile rupture strain) were measured using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7161:2014 and JIS K7127:1999. did The distance between chucks was 50 mm, the specimen size was 10 mm × 70 mm, and the test speed was 20 mm/min.

(3) Glass transition temperature (Tg)

Using the thermomechanical analysis device "TMA/SS6100" manufactured by Hitachi High-Tech Sciences, Inc., in tension mode, the sample size is 2 mm × 20 mm, the load is 0.1 N, and the temperature is sufficient to remove the residual stress under the conditions of 10 ° C/min. Residual stress was removed by raising the temperature to , and then cooled to room temperature. Thereafter, the test piece elongation was measured under the same conditions as the treatment for removing the residual stress, and the point at which the elongation inflection point was observed was determined as the glass transition temperature.

(4) total light transmittance, yellow index (YI), b ^*

Total light transmittance, YI, and b ^* were measured in accordance with JIS K7105:1981, using a color and turbidity simultaneous measuring instrument "COH400" manufactured by Nippon Denshik Industries Co., Ltd.

(5) Thickness phase difference (Rth)

The thickness retardation (Rth) was measured using an ellipsometer "M-220" manufactured by Nippon Spectroscopy Co., Ltd. The value of the thickness phase difference in the measurement wavelength of 590 nm was measured. On the other hand, Rth is expressed by the following formula when the maximum in-plane refractive index of the polyimide film is nx, the minimum is ny, the refractive index in the thickness direction is nz, and the thickness of the film is d.

Rth=[{(nx+ny)/2}-nz]×d

(6) polymerization time

The polymerization time required for the viscosity to be 12 Pa·s or more when the solid content concentration was 20 mass% was defined as the polymerization time. However, the polymerization time means the time for which the internal temperature of the reaction system reaches 190°C and then is maintained at 190°C.

(7) acid resistance (mixed acid ΔYI and mixed acid Δb ^* )

Mixed acid (HNO ₃ (10 mass %) + H ₃ PO ₄ (70 mass %) + CH ₃ COOH (5 mass %) + H ₂ O (15 mass %) heated to 40 ° C. of the polyimide film formed on a glass plate of mixed solution) for 4 minutes, and then washed with water. After washing with water, the moisture was wiped off, heated on a hot plate at 240° C. for 50 minutes, and dried. YI and b ^* were measured before and after the test, and the changes (ΔYI and Δb ^* ) were calculated. In addition, YI measurement and b ^* measurement here were performed in the state (state of glass plate + polyimide film) which formed the polyimide film into a film on the glass plate.

(8) alkali resistance

After immersing the polyimide film formed into a film on the glass plate in the potassium hydroxide aqueous solution of 3 mass % concentration at room temperature for 5 minutes, it washed with water. After washing with water, it was checked whether there was any change in the film surface.

The evaluation criteria of alkali resistance were carried out as follows.

A: There was no change in the film surface.

B: A slight crack entered the film surface.

C: A crack entered the film surface, or the film surface was dissolved.

The tetracarboxylic acid component and diamine component, other components and their abbreviations used in Examples and Comparative Examples are as follows.

<Tetracarboxylic acid component>

HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Corporation; compound represented by formula (a-1))

<Diamine component>

3,3'-DDS: 3,3'-diaminodiphenylsulfone (manufactured by Seika Corporation; compound represented by formula (b-1))

BAPS: bis[4-(4-aminophenoxy)phenyl]sulfone (manufactured by Seika Corporation; compound represented by formula (b-2))

<Others>

GBL: γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation)

TEA: triethylamine (manufactured by Kanto Chemical Co., Ltd.)

<Example 1>

3,3'-DDS 14.135 g (0.057 mol), BAPS 24.527 in a 300 mL 5-neck round-bottom flask equipped with stainless steel semi-lunar stirring blades, nitrogen introduction tube, Dean-Stark with cooling tube, thermometer, and glass end cap. g (0.057 mol), and 41.945 g of GBL were added, and stirred at a system internal temperature of 70° C., a nitrogen atmosphere, and a rotation speed of 200 rpm to obtain a solution.

To this solution, 25.421 g (0.113 mol) of HPMDA and 10.486 g of GBL were added at once, and then 0.573 g of TEA as an imidization catalyst was added, heated with a mantle heater, and the internal temperature of the reaction system was raised to 190° C. over about 20 minutes. raised to The components being distilled were collected, and while the number of rotations was adjusted to match the increase in viscosity, the temperature in the reaction system was maintained at 190° C. and refluxed for about 5 hours.

Then, 187.569 g of GBL was added so that the solid content concentration might be 20 mass %, and after cooling the reaction system internal temperature to 100 degreeC, it further stirred for about 1 hour and homogenized, and obtained the polyimide varnish. The viscosity of the varnish solution was 12 Pa·s at 25°C.

Then, on a glass plate, the obtained polyimide varnish is applied by spin coating, held on a hot plate at 80° C. for 20 minutes, and then heated at 260° C. in an air atmosphere for 30 minutes in a hot air dryer to evaporate the solvent. , a film was obtained. A result is shown in Table 1.

<Example 2>

3,3'-DDS 17.571 g (0.071 mol), BAPS 20.326 in a 300 mL 5-neck round-bottom flask equipped with stainless steel semi-lunar stirring blades, nitrogen inlet tube, Dean-Stark with cooling tube, thermometer, and glass end cap. g (0.047 mol), and 42.041 g of GBL were added, and stirred at a system internal temperature of 70° C., a nitrogen atmosphere, and a rotation speed of 200 rpm to obtain a solution.

To this solution, 26.333 g (0.117 mol) of HPMDA and 10.510 g of GBL were added at once, then 0.594 g of TEA as an imidization catalyst was added, heated with a mantle heater, and the temperature inside the reaction system was raised to 190 over about 20 minutes. was raised to °C. The components being distilled were collected, and while the number of rotations was adjusted to match the increase in viscosity, the temperature in the reaction system was maintained at 190° C. and refluxed for about 4.7 hours.

Then, 187.449 g of GBL was added so that the solid content concentration might be 20 mass %, and after cooling the reaction system internal temperature to 100 degreeC, it further stirred for about 1 hour and homogenized, and obtained the polyimide varnish. The viscosity of the varnish solution was 12 Pa·s at 25°C.

Then, on a glass plate, the obtained polyimide varnish is applied by spin coating, held on a hot plate at 80° C. for 20 minutes, and then heated at 260° C. in an air atmosphere for 30 minutes in a hot air dryer to evaporate the solvent. , a film was obtained. A result is shown in Table 1.

<Comparative Example 1>

3,3'-DDS 5.122 g (0.021 mol), BAPS 35.549 in a 300 mL 5-neck round-bottom flask equipped with stainless steel semi-lunar stirring blades, nitrogen inlet tube, Dean-Stark with cooling tube, thermometer, and glass end cap. g (0.082 mol), and 41.694 g of GBL were added, and stirred at a system internal temperature of 70° C., a nitrogen atmosphere, and a rotation speed of 200 rpm to obtain a solution.

To this solution, 23.028 g (0.103 mol) of HPMDA and 10.388 g of GBL were added at once, and then 0.519 g of TEA as an imidization catalyst was added, heated with a mantle heater, and the temperature inside the reaction system was raised to 190° C. over about 20 minutes. and refluxed for about 7 hours. The viscosity of the varnish solution was 12 Pa·s at 25°C.

Then, 187.883 g of GBL was added so that the solid content concentration might be 20 mass %, and after cooling the reaction system internal temperature to 100 degreeC, it stirred for about 1 hour further and homogenized, and obtained the polyimide varnish.

Then, on a glass plate, the obtained polyimide varnish is applied by spin coating, held on a hot plate at 80° C. for 20 minutes, and then heated at 260° C. in an air atmosphere for 30 minutes in a hot air dryer to evaporate the solvent. , a film was obtained. A result is shown in Table 1.

<Comparative Example 2>

3,3'-DDS 25.239 g (0.101 mol), BAPS 10.949 in a 300 mL 5-neck round-bottom flask equipped with stainless steel semi-lunar stirring blades, nitrogen inlet tube, Dean-Stark with cooling tube, thermometer, and glass end cap. g (0.025 mol), and 42.255 g of GBL were added, and stirred at a system internal temperature of 70° C., a nitrogen atmosphere, and a rotation speed of 200 rpm to obtain a solution.

To this solution, 28.369 g (0.126 mol) of HPMDA and 10.564 g of GBL were added at once, and then 0.640 g of TEA as an imidization catalyst was added, heated with a mantle heater, and the internal temperature of the reaction system was raised to 190° C. over about 20 minutes. raised to The components being distilled were collected, and while the number of rotations was adjusted to match the increase in viscosity, the temperature in the reaction system was maintained at 190° C. and refluxed for about 7.5 hours.

Then, 187.181 g of GBL was added so that the solid content concentration might be 20 mass %, and after cooling the reaction system internal temperature to 100 degreeC, it stirred for about 1 hour further and homogenized, and obtained the polyimide varnish. The viscosity of the varnish solution was 12 Pa·s at 25°C.

Then, on a glass plate, the obtained polyimide varnish is applied by spin coating, held on a hot plate at 80° C. for 20 minutes, and then heated at 260° C. in an air atmosphere for 30 minutes in a hot air dryer to evaporate the solvent. , a film was obtained. A result is shown in Table 1.

[Table 1]

As shown in Table 1, the polyimide films of Examples 1 and 2 used HPMDA as a tetracarboxylic acid component, and 50-60 mol% of 3,3'-DDS and 50-40 mol% of 3,3'-DDS as a diamine component. BAPS was used in combination. As a result, colorless transparency, optical isotropy, acid resistance, and alkali resistance were exhibited, and toughness was excellent. Moreover, the polymerization time was shorter than that of the comparative example.

On the other hand, the polyimide film of Comparative Example 1 was prepared by using HPMDA as a tetracarboxylic acid component and using 20 mol% of 3,3'-DDS and 80 mol% of BAPS as a diamine component. As a result, the thickness retardation (retardation, Rth) was high and the optical isotropy was inferior. Also, the polymerization time was long.

The polyimide film of Comparative Example 2 was prepared by using HPMDA as a tetracarboxylic acid component and using 80 mol% of 3,3'-DDS and 20 mol% of BAPS as a diamine component. As a result, the thickness retardation (retardation, Rth) was low and the optical properties were excellent, but the tensile elongation and tensile strength were low and inferior. Also, the polymerization time was long.

Therefore, a polyimide film prepared by using HPMDA as a tetracarboxylic acid component and 3,3'-DDS and BAPS as a diamine component together in a specific ratio is colorless and transparent, optically isotropic, and has chemical resistance (eg, acid resistance). and alkali resistance), and as a film excellent in toughness, it can be suitably used as a plastic substrate such as a liquid crystal display and a touch panel. Furthermore, the polymerization time is short, so that the energy during manufacturing can be reduced and the manufacturing cost is excellent.

Claims (3)

A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,
The structural unit A includes a structural unit (A-1) derived from a compound represented by the following formula (a-1), and a structural unit derived from a compound represented by the following formula (a-2) (A- 2) not including;
The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1) and a structural unit (B-2) derived from a compound represented by the following formula (b-2) and,
The polyimide resin wherein the proportion of the structural unit (B-1) in the structural unit B is 30 to 70 mol%, and the proportion of the structural unit (B-2) in the structural unit B is 70 to 30 mol%.
[Formula 1]

A polyimide varnish formed by dissolving the polyimide resin according to claim 1 in an organic solvent. A polyimide film comprising the polyimide resin according to claim 1 .