KR20230009888A - Polyimide resin, polyimide varnish and polyimide film - 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 2,2',3,3',5,5'-hexamethyl [ 1,1'-biphenyl] -4,4'-diyl = bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) ) and a structural unit (A2) derived from 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

Description

Polyimide resin, polyimide varnish and polyimide film

The present invention relates to a polyimide resin, a polyimide varnish and a polyimide film.

Polyimide resin is obtained, for example, from aromatic tetracarboxylic acid anhydride and aromatic diamine, and generally has excellent heat resistance, chemical resistance, mechanical properties, and electrical properties due to molecular rigidity, resonance stabilization, and strong chemical bonding. It is widely used in fields such as molding materials, composite materials, electric/electronic components, optical materials, displays, and aerospace.

In the above applications, it is particularly important to have transparency, and studies to enhance the transparency of polyimide resins have been conducted.

Patent Literature 1 discloses a polyimide containing TAHMBP or the like as a structural unit in order to improve transparency, heat resistance, solvent processability, and the like.

International Publication No. 2014/046180

In recent years, applications to displays and front plates that protect them have progressed, and polyimide resins with high elasticity have been required in terms of replacing conventionally used glass materials. However, conventional highly elastic polyimide resins had problems such as poor transparency in many cases.

In addition, recently, since it is used as a display or protective plate of a smartphone having a foldable structure, high elasticity and flexibility are also required, and properties such as the property of recovering the shape after the polyimide film is deformed or the stretching of the film are also required. it is becoming necessary

Therefore, a polyimide resin having these properties has been desired.

That is, the problem to be solved by the present invention is a polyimide resin capable of forming a film having both high elasticity and transparency, high elasticity, excellent strain recovery and elongation, and both high elasticity and transparency, strain recovery and elongation. It is to provide an excellent polyimide film.

As a result of intensive examination, the inventors have found that a polyimide resin having structural units derived from two specific types of tetracarboxylic dianhydride can form a film having both high elasticity and transparency, and having high elasticity, excellent deformation recovery and elongation. found, and led to the present invention.

That is, the present invention relates to the following [1] to [8].

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

A polyimide resin in which the structural unit A contains a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2).

[Formula 1]

[2] The polyimide resin according to [1] above, wherein the ratio of the structural unit (A2) to the structural unit A is 10 to 80 mol%.

[3] The polyimide resin according to [1] or [2] above, wherein the structural unit B includes a structural unit (B1) derived from a compound represented by the following general formula (b1).

[Formula 2]

(In formula (b1), X is a single bond or an oxygen atom.)

[4] The polyimide resin according to any one of [1] to [3] above, wherein the structural unit B further contains a structural unit (B2) derived from a compound represented by the following formula (b2).

[Formula 3]

[5] The polyimide resin according to any one of [1] to [4] above, wherein the ratio of the structural unit (A1) to the structural unit A is 20 to 90 mol%.

[6] The polyimide resin according to any one of [3] to [5] above, wherein the ratio of the structural unit (B1) to the structural unit B is 70 mol% or more.

[7] A polyimide varnish obtained by dissolving the polyimide resin according to any one of [1] to [6] above in an organic solvent.

[8] A polyimide film containing the polyimide resin according to any one of [1] to [6] above.

According to the present invention, a polyimide resin capable of forming a film having both high elasticity and transparency and having high elasticity, excellent deformation recovery and elongation, a polyimide varnish containing the polyimide resin, and high elasticity and transparency, It is possible to provide a polyimide film excellent in deformation recovery and elongation.

1 is a conceptual diagram showing a method for measuring deformation recovery of a polyimide film.

[Polyimide resin]

The polyimide resin of the present invention is a polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,

Structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2).

[Formula 4]

Hereinafter, the polyimide resin of the present invention will be described.

[Unit A]

The structural unit A contained in the polyimide of the present invention is a structural unit derived from tetracarboxylic dianhydride occupied in the polyimide resin.

The structural unit A includes a structural unit (A1) derived from a compound represented by the formula (a1) and a structural unit (A2) represented by the formula (a2).

The compound represented by the formula (a1) is 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl = bis(1,3 -dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-TME).

When structural unit A contains structural unit (A1), the elasticity modulus of the polyimide resin obtained improves.

The compound represented by the formula (a2) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA).

When structural unit A contains structural unit (A2), transparency can be improved and elongation can also be improved, maintaining elastic modulus.

In this way, by having structural units derived from the above two kinds of tetracarboxylic dianhydrides, the reason why both high elasticity and transparency are excellent, and the reason why deformation recovery and elongation are excellent is not clear, but the rigidity of the ester group and the transparency of the alicyclic compound It is thought to originate from

The ratio of structural unit (A1) to structural unit A is preferably 20 to 90 mol%, more preferably 20 to 80 mol%, even more preferably 30 to 80 mol%, still more preferably is 50 to 80 mol%, more preferably 50 to 70 mol%, still more preferably 55 to 65 mol%.

The ratio of the structural unit (A2) to the structural unit A is preferably 10 to 80 mol%, more preferably 20 to 80 mol%, still more preferably 20 to 70 mol%, still more preferably is 20 to 50 mol%, more preferably 30 to 50 mol%, still more preferably 35 to 45 mol%.

The ratio of the total of structural units (A1) and (A2) in structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more. to be. The upper limit of the ratio of the total of the constituent units (A1) and (A2) is not particularly limited, and is 100 mol% or less. The structural unit A may consist only of the structural unit (A1) and the structural unit (A2).

The molar ratio [(A1):(A2)] of the structural units (A1) and (A2) in the structural unit A is preferably 20: from the viewpoint of improving the elastic modulus, elongation, transparency and deformation recovery. 80 to 90:10, more preferably 20:80 to 80:20, still more preferably 30:70 to 80:20, still more preferably 50:50 to 80:20, still more preferably Preferably it is 50:50 to 70:30, and more preferably 55:45 to 65:35.

The polyimide resin of the present invention is a structural unit other than the structural unit (A1) and the structural unit (A2) in the structural unit A, within the scope of not impairing the effects of the present invention, represented by the formula (a1) It may contain structural units derived from tetracarboxylic dianhydride other than the compound and the compound represented by the formula (a2).

Tetracarboxylic dianhydrides other than the compound represented by the formula (a1) and the compound represented by the formula (a2) are not particularly limited, but pyromellitic anhydride, 2,3,5,6-toluenetetracarb Aromatic tetracarboxylic acid dianhydride, such as carboxylic acid dianhydride and 1,4,5,8-naphthalene tetracarboxylic acid dianhydride; 1,2,4,5-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2.2]octa-7-en-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyltetracarboxylic acid alicyclic tetracarboxylic acid dianhydrides such as anhydrides or regioisomers thereof; and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. These can be used individually or in combination of 2 or more types.

Meanwhile, in the present specification, aromatic tetracarboxylic acid dianhydride means tetracarboxylic acid dianhydride containing one or more aromatic rings, and alicyclic tetracarboxylic acid dianhydride includes one or more alicyclic rings, and also aromatic rings. It means a tetracarboxylic acid dianhydride that does not contain, and the aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride that does not contain an aromatic ring or an alicyclic ring.

[Constituent unit B]

The structural unit B contained in the polyimide of the present invention is a structural unit derived from diamine.

Although there is no restriction|limiting in the structural unit derived from the diamine contained in structural unit B, the structural unit demonstrated below preferable.

It is preferable that the structural unit B contained in the polyimide of this invention contains the structural unit (B1) derived from the compound represented by the following general formula (b1). By including the structural unit (B1), the modulus of elasticity, elongation, transparency and recovery from deformation are improved.

[Formula 5]

(In formula (b1), X is a single bond or an oxygen atom.)

The structural unit (B1) is selected from the group consisting of a structural unit (B11) derived from a compound represented by the following formula (b11) and a structural unit (B12) derived from a compound represented by the following formula (b12) It is preferable to include at least one structural unit, and it is more preferable to include a structural unit (B11) derived from a compound represented by the following formula (b11) from the viewpoints of transparency, elastic modulus and colorlessness. Moreover, from the viewpoint of stretching, it is more preferable to include a structural unit (B12) derived from a compound represented by the following formula (b12).

The structural unit (B1) may contain only one of the structural unit (B11) or the structural unit (B12), or may contain both.

[Formula 6]

The compound represented by formula (b11) is 2,2'-bis(trifluoromethyl)benzidine (TFMB).

The compound represented by formula (b12) is 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA).

The ratio of structural unit (B1) to structural unit B is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 50 mol% or more, still more preferably 70 mol% % or more, and more preferably 85 mol% or more. In addition, the upper limit of the ratio of structural unit (B1) is not particularly limited and is 100 mol% or less.

The structural unit B may include a structural unit (B2) derived from a compound represented by the following formula (b2), and from the viewpoint of improving the elastic modulus, a structural unit derived from a compound represented by the following formula (b2) (B2) ) is preferably included.

[Formula 7]

The ratio of structural unit (B2) to structural unit B is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 30 mol% or less, from the viewpoints of transparency and deformation recovery. 15 mol% or less may be sufficient. The lower limit of the proportion of the structural unit (B2) is not particularly limited and is 0 mol% or more, but is preferably 5 mol% or more from the viewpoint of improving the elastic modulus.

When structural unit B contains structural unit (B1) and structural unit (B2), the ratio of the total of structural unit (B1) and structural unit (B2) in structural unit B is preferably 50 mol% or more. , more preferably 70 mol% or more, and still more preferably 90 mol% or more. The upper limit of the ratio of the total of the structural units (B1) and (B2) is not particularly limited and is 100 mol% or less. The structural unit (B) may consist only of the structural unit (B1) and the structural unit (B2).

The polyimide resin of the present invention is represented by the general formula (b1) as a structural unit other than the structural unit (B1) and the structural unit (B2) in the structural unit B, within the scope of not impairing the effects of the present invention. and structural units derived from diamine other than the compound represented by the formula (b2).

Although diamines other than the compound represented by the said general formula (b1) and the compound represented by the said formula (b2) are not specifically limited, 1,4-phenylenediamine, p-xylylenediamine, 1,5-diameter Minonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diaminodiphenylmethane, 1,4- Bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis(4-aminophenyl)hexafluoropropane, 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 Aromatics such as '-bis(4-aminophenyl)terephthalamide, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and 1,4-bis(4-aminophenoxy)benzene diamine; alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; aliphatic diamines such as ethylenediamine and hexamethylenediamine; And modified silicon diamine is mentioned. These can be used individually or in combination of 2 or more types.

Meanwhile, in the present specification, aromatic diamine means diamine containing one or more aromatic rings, and alicyclic diamine means diamine containing one or more alicyclic rings and not containing aromatic rings. Aliphatic diamine means diamine containing one or more alicyclic rings. It means diamine containing neither an aromatic ring nor an alicyclic ring.

[Characteristics of polyimide resin, etc.]

The number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 100,000 from the viewpoint of mechanical strength of the polyimide film obtained. On the other hand, the number average molecular weight of the polyimide resin can be measured by gel filtration chromatography or the like.

The polyimide resin of the present invention may further contain various additives within a range not impairing the effects of the present invention. Examples of additives include antioxidants, light stabilizers, surfactants, flame retardants, plasticizers, and polymer compounds other than the above polyimide resins.

Examples of the polymer compound include polyimide other than the polyimide resin of the present invention, polycarbonate, polystyrene, polyamide, polyamideimide, polyester such as polyethylene terephthalate, polyethersulfone, polycarboxylic acid, polyacetal, and polyphenylene. ether, polysulfone, polybutylene, polypropylene, polyacrylamide, polyvinyl chloride and the like.

[Method for producing polyimide resin]

The polyimide resin of the present invention can be produced by reacting a diamine component with a tetracarboxylic acid component containing the above-described compound providing the structural unit (A1) and the compound providing the structural unit (A2).

Examples of the compound imparting the structural unit (A1) include compounds represented by formula (a1), but are not limited thereto, and may be derivatives thereof within the scope of imparting the same structural unit. Examples of the derivative include tetracarboxylic acid corresponding to tetracarboxylic dianhydride represented by formula (a1) and alkyl esters of the tetracarboxylic acid. As a compound which gives structural unit (A1), the compound represented by formula (a1) (ie, dianhydride) is preferable.

Similarly, as the compound giving the structural unit (A2), the compound represented by formula (a2) can be mentioned, but it is not limited thereto, and a derivative thereof may be used within the range giving the same structural unit. Examples of the derivative include tetracarboxylic acid corresponding to tetracarboxylic dianhydride represented by formula (a2) and alkyl esters of the tetracarboxylic acid. As a compound which gives structural unit (A-2), the compound represented by formula (a2) (namely, a dianhydride) is preferable.

The tetracarboxylic acid component contains preferably 20 to 90% by mol, more preferably 20 to 80% by mol, still more preferably 30 to 80% by mol of the compound that provides the structural unit (A1). and more preferably contains 50 to 80 mol%, even more preferably contains 50 to 70 mol%, and even more preferably contains 55 to 65 mol%.

The tetracarboxylic acid component contains preferably 10 to 80% by mol, more preferably 20 to 80% by mol, still more preferably 20 to 70% by mol of the compound that provides the structural unit (A2). and more preferably contains 20 to 50 mol%, even more preferably contains 30 to 50 mol%, and even more preferably contains 35 to 45 mol%.

The content ratio of the sum of the compound providing the structural unit (A1) and the compound providing the structural unit (A2) is preferably 50 mol% or more, and more preferably 70 mol% or more, of all the tetracarboxylic acid components. , and more preferably 90 mol% or more. The upper limit of the total content of the compound providing the structural unit (A1) and the compound providing the structural unit (A2) is not particularly limited, and is 100 mol% or less. The tetracarboxylic acid component may consist only of the compound providing the structural unit (A1) and the compound providing the structural unit (A2).

The molar ratio [(A1):(A2)] of the compound giving the structural unit (A1) and the compound giving the structural unit (A2) in the tetracarboxylic acid component is preferably from the viewpoint of improving the elastic modulus and transparency. is 20:80 to 90:10, more preferably 20:80 to 80:20, still more preferably 30:70 to 80:20, still more preferably 50:50 to 80:20, More preferably, it is 50:50 to 70:30, and even more preferably, it is 55:45 to 65:35.

The tetracarboxylic acid component may contain compounds other than the compound providing the structural unit (A1) and the compound providing the structural unit (A2), and examples of the compound include the above-mentioned aromatic tetracarboxylic dianhydride, alicyclic Formula tetracarboxylic acid dianhydride, aliphatic tetracarboxylic acid dianhydride, and their derivatives (tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.) are mentioned.

The compound optionally included in the tetracarboxylic acid component (that is, the compound other than the compound providing the structural unit (A1) and the structural unit (A2)) may be one type or two or more types.

Although there is no restriction|limiting in the diamine component, It is preferable that the compound which provides the structural unit (B1) mentioned above is included.

Examples of the compound imparting the structural unit (B1) include compounds represented by formula (b1), but are not limited thereto, and may be derivatives thereof within the scope of imparting the same structural unit. Examples of the derivative include diisocyanate corresponding to the diamine represented by formula (b1). As a compound which gives structural unit (B1), the compound represented by formula (b1) (namely, diamine) is preferable.

The diamine component contains preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 50 mol%, and even more preferably 50 mol% of the compound providing the structural unit (B1). contains 70 mol% or more, and more preferably contains 85 mol% or more. In addition, the upper limit of the ratio of the compound giving the structural unit (B1) is not particularly limited, and is 100 mol% or less.

The diamine component may contain a compound that imparts the structural unit (B2), and preferably contains a compound that imparts the structural unit (B2) from the viewpoint of improving the elastic modulus.

Examples of the compound imparting the structural unit (B2) include compounds represented by formula (b2), but are not limited thereto, and may be derivatives thereof within the scope of imparting the same structural unit. Examples of the derivative include diisocyanate corresponding to diamine represented by formula (b2). As a compound which gives structural unit (B2), the compound represented by formula (b2) (namely, diamine) is preferable.

The content ratio of the sum of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) is preferably 50 mol% or more, more preferably 70 mol% or more, of all diamine components, More preferably, it is 90 mol% or more. The upper limit of the total content of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) is not particularly limited, and is 100 mol% or less. The diamine component may consist only of the compound which provides structural unit (B1) and the compound which provides structural unit (B2).

The diamine component may contain compounds other than the compound providing the structural unit (B1) and the compound providing the structural unit (B2), and examples of the compound include the above-mentioned aromatic diamine, alicyclic diamine, and aliphatic diamine; modified silicone diamine, and derivatives thereof (such as diisocyanate).

The compound optionally included in the diamine component (that is, compounds other than the compound providing the structural unit (B1) and the compound providing the structural unit (B2)) may be one kind or two or more kinds.

When producing the polyimide resin according to the present invention, the amount ratio of the tetracarboxylic acid component and the diamine component added is preferably 0.9 to 1.1 mol of the diamine component per 1 mol of the tetracarboxylic acid component.

When producing the polyimide resin of the present invention, an end capping agent may be used in addition to the tetracarboxylic acid component and the diamine component. As the end capping agent, monoamines or dicarboxylic acids are preferable. The amount of the endcapping agent to be introduced is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, per 1 mol of the tetracarboxylic acid component. Preferred monoamine endcaps include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3- Ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. are mentioned. Among these, benzylamine and aniline are more preferable. As the dicarboxylic acid endcapping agent, dicarboxylic acids are preferable, and some of them may be ring-closed. Preferred dicarboxylic acids include phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, and cyclohexane-1,2-dicarboxylic acid. levonic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and the like. Among these, phthalic acid and phthalic anhydride are more preferable.

The method for reacting the tetracarboxylic acid component and the diamine component described above is not particularly limited, and a known method can be used.

As a specific reaction method, (1) a method of introducing a tetracarboxylic acid component, a diamine component, and a reaction solvent into a reactor, stirring at 10 to 110 ° C. for 0.5 to 30 hours, and then raising the temperature to perform an imidation reaction, ( 2) After dissolving the diamine component and the reaction solvent in a reactor, the tetracarboxylic acid component is added, stirred at 10 to 110 ° C. for 0.5 to 30 hours as necessary, and then the temperature is raised to perform an imidation reaction; (3) A method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are introduced into a reactor, and the temperature is immediately raised to perform an imidation reaction.

The reaction solvent used for production of the polyimide resin may be one capable of dissolving the resulting polyimide resin without inhibiting the imidation reaction. Examples thereof include aprotic solvents, phenolic solvents, ether solvents, and carbonate solvents.

Specific examples of the aprotic solvent include N,N-dimethylisobutylamide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-methylcaprolactam. , Amide-based solvents such as 1,3-dimethylimidazolidinone and tetramethylurea, lactone-based solvents such as γ-butyrolactone and γ-valerolactone, hexamethylphosphoricamide, hexamethylphosphinetriamide, etc. phosphorus-containing amide-based solvents, sulfur-containing solvents such as dimethylsulfone, dimethylsulfoxide, and sulfolane, ketone-based solvents such as acetone, cyclohexanone, and methylcyclohexane, amine-based solvents such as picoline and pyridine, and acetic acid (2 -Methoxy-1-methylethyl), etc. are mentioned.

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-methoxyethyl) ether, Toxyethoxy) ethyl] ether, tetrahydrofuran, 1,4-dioxane, etc. are mentioned.

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

Among the above reaction solvents, amide-based solvents or lactone-based solvents are preferable. In addition, the above reaction solvents may be used alone or in combination of two or more.

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

In the imidation reaction, a known imidation catalyst can be used. Examples of the imidation catalyst include base catalysts and acid catalysts.

As the base catalyst, pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine , organic base catalysts such as imidazole, N,N-dimethylaniline, and N,N-diethylaniline; and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogencarbonate, and sodium hydrogencarbonate. there is.

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

Among the above, from the viewpoint of handleability, it is preferable to use a base catalyst, more preferably an organic base catalyst, and even more preferable to use triethylamine.

In the case of using the above catalyst, the temperature of the imidation reaction is preferably 120 to 250 ° C, more preferably 160 to 190 ° C, still more preferably 180 to 190 ° C, from the viewpoint of reaction rate and suppression of gelation, etc. . In addition, the reaction time is preferably 0.5 to 10 hours after the start of distillation of generated water.

On the other hand, the temperature of the imidation reaction in the case of not using a catalyst is preferably 200 to 350°C.

[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 may be any organic solvent capable of dissolving the polyimide resin, and is not particularly limited, but it is preferable to use the above-mentioned compounds alone or in a mixture of two or more kinds as the reaction solvent used for production of the polyimide resin.

It is preferable that the polyimide varnish of this invention contains 5-60 mass % of the polyimide resin of this invention, and it is more preferable that it contains 5-45 mass %. The viscosity of the polyimide varnish is preferably 0.1 to 200 Pa·s, and more preferably 0.5 to 150 Pa·s.

[Polyimide film]

The polyimide film of the present invention contains the polyimide resin.

That is, it has structural unit A derived from tetracarboxylic dianhydride and structural unit B derived from diamine, and structural unit A is derived from a compound represented by the following formula (a1) and the following formula A polyimide resin containing a structural unit (A2) derived from the compound represented by (a2) is included.

By including such a polyimide resin, the polyimide film of the present invention has both high elasticity and transparency, and is also excellent in deformation recovery.

The method for producing the polyimide film of the present invention is not particularly limited, and known methods can be used. For example, a solution containing the polyimide resin of the present invention or a solution containing the polyimide resin of the present invention and the various additives described above may be mixed into a smooth surface such as a glass plate, a metal plate, or plastic. After coating on a support or forming into a film, a method of removing solvent components such as an organic solvent contained in the solution is exemplified.

The solution containing the polyimide resin may be a polyimide resin solution itself obtained by a polymerization method. In addition, the polyimide resin solution may be a mixture of at least one selected from the compounds exemplified above as a solvent in which the polyimide resin is dissolved. As described above, the thickness of the polyimide film of the present invention can be easily controlled by adjusting the solid content concentration and viscosity of the solution containing the polyimide resin.

A release agent may be applied to the surface of the support, if necessary. As a method of applying the solution containing the polyimide resin or the polyimide resin composition to the support and then heating to evaporate the solvent component, the following method is preferable. That is, after evaporating the solvent at a temperature of 120° C. or less to obtain a self-supporting film, the self-supporting film is peeled off from the support, the ends of the self-supporting film are fixed, and the boiling point of the solvent component used is 350° C. or higher. It is preferable to manufacture a polyimide film by drying at the following temperature. Further, drying in a nitrogen atmosphere is preferred. The pressure of the dry atmosphere may be any of reduced pressure, normal pressure, and increased pressure.

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

In the present invention, a polyimide film having a total light transmittance of preferably 85% or more, more preferably 88% or more, still more preferably 89% or more at a thickness of 50 μm can be used.

In the present invention, a polyimide film having a yellow index (YI value) of preferably 8.0 or less, more preferably 7.5 or less, still more preferably 6.0 or less, and still more preferably 4.0 or less can be used.

The total light transmittance and YI value of the polyimide film can be specifically measured by the methods described in Examples.

The polyimide film containing the polyimide resin of the present invention is suitably used as a film for various members such as color filters, flexible displays, semiconductor components, and optical members.

Example

The present invention is specifically described by the following examples. However, the present invention is not limited at all by these examples.

The physical properties of the polyimide films obtained in the following examples and comparative examples were measured by the methods shown below.

(1) Film thickness

The film thickness was measured using a micrometer manufactured by Mitutoyo Corporation.

(2) Tensile modulus (evaluation of elasticity), tensile strength

The measurement was performed using a tensile tester "Strograph VG1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127.

(3) Tensile elongation at break (elongation evaluation)

The tensile elongation at break was determined by a tensile test (measurement of elongation) in accordance with JIS K7127. As the test piece, one having a width of 10 mm and a thickness of 10 to 70 μm was used.

(4) Total light transmittance (evaluation of transparency), YI value

The measurement was based on ASTM E313-05, and was performed using a color and turbidity simultaneous measuring instrument "COH7700" manufactured by Nippon Denshoku Kogyo Co., Ltd.

(5) Deformation recovery

As shown in Fig. 1 (a), a polyimide film 1 cut into a 10 mm width x 100 mm length was fixed with a jig at R = 3 mm, and left still at 65°C and a relative humidity of 90% for 24 hours. Thereafter, the jig was removed at 23 ° C. and a relative humidity of 50%, and after leaving it still for 2 hours, the deformation recovery was evaluated by measuring the angle θ showing the return of the film in FIG. 1 (b). On the other hand, the smaller the measured angle, the better the deformation recovery property, and the smaller the value, the better.

[Example 1]

2,2'-bis(trifluoromethyl ) Benzidine (manufactured by Wakayama Seishi Kogyo Co., Ltd., a compound represented by formula (b11), hereinafter TFMB) 18.76 g (0.059 mol), γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd., hereinafter GBL) 85.8 g as an organic solvent, imidation 0.296 g of triethylamine (manufactured by Kanto Chemical Co., Ltd., hereinafter referred to as TEA) was added as a catalyst, and stirred at a rotation speed of 150 rpm under a nitrogen atmosphere at a system temperature of 70° C. to obtain a solution. To this, as a tetracarboxylic acid component, 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd., a compound represented by formula (a2), hereinafter HPMDA) 5.25 g (0.023 mol) and 2, 2',3,3',5,5'-Hexamethyl[1,1'-biphenyl]-4,4'-diyl=bis(1,3-dioxo-1,3-dihydro-2- After adding 21.75 g (0.035 mol) of benzofuran-5-carboxylate) (manufactured by Honshu Chemical Industry Co., Ltd., a compound represented by the formula (a1), hereinafter TMPBP-TME) and 21.3 g of GBL, it is heated with a mantle heater. By heating, the temperature in the reaction system was raised to 190°C over about 20 minutes. A polyimide solution was obtained by collecting distilled-off components and refluxing for 2 hours while maintaining the temperature inside the reaction system at 190°C while adjusting the number of rotations according to the increase in viscosity. After that, when the temperature inside the reaction system is cooled to 120°C, N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) is added to a predetermined solid content concentration, and stirred for about 3 hours to homogenize, and the solid content concentration is 15.0% by mass. A polyimide varnish (A) was obtained.

Then, the polyimide varnish (A) is applied on the glass substrate, maintained at 60° C. for 20 minutes, 80° C. for 20 minutes, and 100° C. for 30 minutes to evaporate the solvent, resulting in a transparent primary drying film having self-supporting properties. was obtained, and further, the film was fixed to a stainless steel mold, and the solvent was removed by drying at 220°C for 20 minutes in an air atmosphere to obtain a polyimide film. Table 1 shows the measurement results and evaluation results of physical properties.

[Example 2]

The amount of TFMB was changed to 17.27 g (0.054 mol), and 0.91 g (0.0060 mol) of 3,5-diaminobenzoic acid (manufactured by Nippon Sunryang Chemical Co., Ltd., a compound represented by formula (b2), hereinafter referred to as 3,5-DABA) was added. ) was added, and the amount of HPMDA was changed to 5.37 g (0.024 mol) and the amount of TMPBP-TME was changed to 22.23 g (0.036 mol), by the same method as in Example 1, polyi having a solid content concentration of 15.0 mass% A mid varnish (B) was obtained. A polyimide film was obtained by the same method as in Example 1 using the obtained polyimide varnish (B). Table 1 shows the measurement results and evaluation results of physical properties.

[Example 3]

The amount of TFMB was changed to 19.56 g (0.061 mole), the amount of 3,5-DABA was changed to 1.03 g (0.0068 mole), the amount of HPMDA was changed to 9.13 g (0.041 mole), and the amount of TMPBP-TME was changed to 16.79 g (0.027 mole). A polyimide varnish (C) having a solid content concentration of 15.0% by mass was obtained in the same manner as in Example 1 except for changing to mole). A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (C). Table 1 shows the measurement results and evaluation results of physical properties.

[Example 4]

The amount of TFMB was changed to 22.56 g (0.070 mol), 3,5-DABA was added at 1.19 g (0.0078 mol), the amount of HPMDA was 14.04 g (0.063 mol), and the amount of TMPBP-TME was 9.68 g (0.016 mol). A polyimide varnish (D) having a solid content concentration of 15.0% by mass was obtained in the same manner as in Example 1 except for changing to mole). A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (D). Table 1 shows the measurement results and evaluation results of physical properties.

[Example 5]

TFMB was 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (manufactured by ChinaTech Chemical (Taijin) Co., Ltd., a compound represented by formula (b12), hereinafter referred to as 6FODA) 19.44 g (0.058 mol), the amount of HPMDA was changed to 5.18 g (0.023 mol), and the amount of TMPBP-TME was changed to 21.46 g (0.035 mol), by the same method as in Example 1, solid content A polyimide varnish (E) having a concentration of 15.0% by mass was obtained. A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (E). Table 1 shows the measurement results and evaluation results of physical properties.

[Example 6]

TFMB was changed to 17.79 g (0.053 mol) of 6FODA, 0.90 g (0.0059 mol) of 3,5-DABA was added, the amount of HPMDA was 5.27 g (0.024 mol), and the amount of TMPBP-TME was 21.82 g (0.035 mol). ), a polyimide varnish (F) having a solid content concentration of 15.0% by mass was obtained by the same method as in Example 1 except for changing to . A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (F). Table 1 shows the measurement results and evaluation results of physical properties.

[Comparative Example 1]

A solid content concentration of 15.0% by mass was obtained in the same manner as in Example 1, except that the amount of TFMB was 15.96 g (0.050 mol) and HPMDA was not used, and the amount of TMPBP-TME was changed to 30.83 g (0.050 mol). A polyimide varnish (G) was obtained. A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (G). Table 1 shows the measurement results and evaluation results of physical properties.

[Comparative Example 2]

A polyimide varnish was prepared in the same manner as in Example 1, except that the amount of TFMB was changed to 37.75 g (0.12 mol) and the amount of HPMDA was changed to 26.43 g (0.12 mol) without using TMPBP-TME. , a polyimide varnish (H) having a solid content concentration of 20% by mass was obtained. A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (H).

[Comparative Example 3]

TFMB was 6FODA 38.44 g (0.11 mol) TMPBP-TME was not used and the amount of HPMDA was changed to 25.63 g (0.11 mol), by the same method as in Example 1, polyi having a solid content concentration of 20% by mass Mid varnish (I) was obtained. A film was obtained by the same method as in Example 1 using the obtained polyimide varnish (I). Table 1 shows the measurement results and evaluation results of physical properties.

[Table 1]

From Table 1, it can be seen that the polyimide films of Examples 1 to 6 have both transparency and elastic modulus, and are also excellent in deformation recovery and elongation.

Claims (8)

A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,
A polyimide resin in which structural unit A contains a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2).
[Formula 1]

According to claim 1,
The ratio of the structural unit (A2) to the structural unit A is 10 to 80 mol%, a polyimide resin. According to claim 1 or 2,
The polyimide resin in which the said structural unit B contains the structural unit (B1) derived from the compound represented by the following general formula (b1).
[Formula 2]

(In formula (b1), X is a single bond or an oxygen atom.) According to any one of claims 1 to 3,
The polyimide resin in which the said structural unit B further contains the structural unit (B2) derived from the compound represented by the following formula (b2).
[Formula 3]

According to any one of claims 1 to 4,
A polyimide resin in which the ratio of the structural unit (A1) to the structural unit A is 20 to 90 mol%. According to any one of claims 3 to 5,
The polyimide resin, wherein the ratio of the structural unit (B1) to the structural unit B is 70 mol% or more. A polyimide varnish obtained by dissolving the polyimide resin according to any one of claims 1 to 6 in an organic solvent. A polyimide film comprising the polyimide resin according to any one of claims 1 to 6.

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