TW201943766A - Polyimide resin, polyimide varnish and polyimide film - Google Patents

Abstract

The invention provides a polyimide film having structural units A derived from a tetracarboxylic dianhydride and structural units B derived from a diamine, wherein the structural units A include a structural unit (A-1) derived from a compound represented by formula (a-1) shown below and a structural unit (A-2) derived from a compound represented by formula (a-2) shown below, the structural units B include a structural unit (B-1) derived from a compound represented by formula (b-1) shown below, and the structural units A do not contain a structural unit (A-X) derived from a compound represented by formula (a-x) shown below. The invention also provides a polyimide varnish and a polyimide film containing the above polyimide resin.

Description

Polyimide resin, polyimide varnish, and polyimide film

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

In general, because polyimide resins have excellent mechanical properties and heat resistance, there have been discussions of various uses in fields such as electric-electronic parts. For example, in order to reduce the weight and flexibility of devices, it is desirable to replace glass substrates used in image display devices such as liquid crystal displays and OLED displays with plastic substrates. Research on amine films. Polyimide films for such applications require colorless transparency.

If the varnish applied on a glass support or a silicon wafer is heated and hardened to form a polyimide film, residual stress will be generated in the polyimide film. If the residual stress of the polyimide film is large, there will be a problem of warping of the glass support and the silicon wafer, so the polyimide film also needs to reduce the residual stress.
Patent Document 1 discloses a polyimide resin that provides a film with a low residual stress, using 4,4'-oxydiphthalic dianhydride as a tetracarboxylic acid component and using a number average molecular weight of 1,000. Polyimide resin synthesized by α, ω-aminopropyl polydimethylsiloxane and 4,4'-diamino diphenyl ether as diamine components.
[Previous Technical Literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-232383

[Questions to be solved by the invention]

As described above, polyimide films require colorless transparency and low residual stress, but it is not easy to improve these properties while maintaining excellent mechanical properties and heat resistance.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a polyimide resin that can form a thin film having excellent mechanical properties, heat resistance, and colorless transparency and low residual stress; and a polyimide resin containing the same Polyimide varnish and polyimide film of amine resin.
[Means for solving problems]

The inventors of this case found that a polyimide resin containing a combination of specific constituent units can solve the above-mentioned problems and completed the invention.

That is, the present invention relates to the following [1] to [5].
[1]
A polyfluorene imide resin having a constitutional unit A derived from a tetracarboxylic dianhydride and a constitutional unit B derived from a 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 (A-2) derived from a compound represented by the following formula (a-2),
The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1),
The constituent unit A does not include a constituent unit (AX) derived from a compound represented by the following formula (ax),
[Chemized 1]

[2]
Such as the polyimide resin of [1], in which,
The ratio of the constituent unit (A-1) in the constituent unit A is 50 to 90 mol%,
The ratio of the structural unit (A-2) in the structural unit A is 10 to 50 mol%.
[3]
Such as [1] or [2], polyimide resin, where:
The ratio of the structural unit (B-1) in the structural unit B is 50 mol% or more.
[4]
A polyimide varnish is obtained by dissolving a polyimide resin according to any one of [1] to [3] in an organic solvent.
[5]
A polyimide film comprising the polyimide resin according to any one of [1] to [3].
[Effect of Invention]

According to the present invention, a thin film having excellent mechanical properties, heat resistance, and colorless transparency and low residual stress can be formed.

[Polyimide resin]
The polyfluorene imide resin of the present invention has a constitutional unit A derived from a tetracarboxylic dianhydride and a constitutional unit B derived from a diamine. The constitutional unit A includes a constitutional unit (A- 1), and a constituent unit (A-2) derived from a compound represented by the following formula (a-2), and the constituent unit B includes a constituent unit (B-1) derived from a compound represented by the following formula (b-1), a constituent unit A does not contain a constituent unit (AX) derived from a compound represented by the following formula (ax).
［Chemical 2］

> Construction unit A>
The constitutional unit A is a constitutional unit derived from a tetracarboxylic dianhydride occupied in the polyfluorene imide resin, and includes a constitutional unit (A-1) derived from a compound represented by the following formula (a-1), and derived from the following formula (a -2) The structural unit (A-2) of the compound represented by the compound, and does not include the structural unit (AX) derived from the compound represented by the following formula (ax).
［Chemical 3］

The compound represented by the formula (a-1) is norbornane-2-spiro-α-cyclopentanone-α'-spiro-2 ''-norbornane-5,5 '', 6,6 ''-tetrakis Carboxylic dianhydride.

The compound represented by the formula (a-2) is a biphenyltetracarboxylic dianhydride (BPDA). As a specific example, 3,3 ', 4,4'-linked represented by the following formula (a-2s) may be mentioned. Pyromellitic dianhydride (s-BPDA), 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2a), ) Represents 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride (i-BPDA).
［Chemical 4］

By including both the constituent unit (A-1) and the constituent unit (A-2), the constituent unit A can improve the mechanical properties, heat resistance, and colorless transparency of the film, and reduce residual stress.

The compound represented by formula (ax) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.
In the present invention, the constituent unit A does not include a constituent unit (AX) derived from a compound represented by the formula (ax). That is, the polyimide resin of the present invention does not contain a constituent unit (AX).

The ratio of the constituent unit (A-1) in the constituent unit A is preferably 50 to 90 mol%, more preferably 55 to 85 mol%, and still more preferably 60 to 80 mol%.
The ratio of the constituent unit (A-2) in the constituent unit A is preferably 10 to 50 mol%, more preferably 15 to 45 mol%, and still more preferably 20 to 40 mol%.
The total ratio of the constituent units (A-1) and (A-2) in the constituent unit A is preferably 50 mol% or more, more preferably 70 mol% or more, and more preferably 90 mol% or more. Should be more than 99 mol%. The upper limit of the ratio of the total of the constituent units (A-1) and (A-2) is not particularly limited, and is 100 mol%. The constituent unit A may be composed of only the constituent unit (A-1) and the constituent unit (A-2).

The constituent unit A may include constituent units other than the constituent units (A-1) and (A-2) (except for the constituent unit (AX)). The tetracarboxylic dianhydride providing such a structural unit is not particularly limited, and examples include pyromellitic dianhydride, 9,9'-bis (3,4-dicarboxyphenyl) fluorene dianhydride, and 4, Aromatic tetracarboxylic dianhydrides such as 4 '-(hexafluoroisopropylidene) diphthalic anhydride (except for compounds represented by formula (a-2)); 1,2,3,4-cyclobutane Alicyclic tetracarboxylic dianhydrides such as tetracarboxylic dianhydride (except for compounds represented by formula (a-1) and compounds represented by formula (ax)); and 1,2,3,4-butanetetracarboxylic acid dianhydride An aliphatic tetracarboxylic dianhydride such as anhydride.
In the present specification, an aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and an alicyclic tetracarboxylic dianhydride means an aromatic tetracarboxylic dianhydride containing one or more alicyclic rings and does not contain aromatics. Ring tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride containing neither aromatic ring nor alicyclic ring.
The constituent units other than the constituent units (A-1) and (A-2) arbitrarily included in the constituent unit A may be one type or two or more types.

> Construction unit B>
The constitutional unit B is a constitutional unit derived from a diamine which is occupied in the polyfluorene imide resin, and includes a constitutional unit (B-1) derived from a compound represented by the following formula (b-1).
［Chemical 5］

The compound represented by formula (b-1) is 2,2'-bis (trifluoromethyl) benzidine.
By including the constitutional unit (B-1), the constitutional unit B can improve the colorless transparency and heat resistance of the film, and reduce the residual stress.

The ratio of the constituent unit (B-1) in the constituent unit B is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and even more preferably 99 mol% or more. The upper limit value of the ratio of the constituent unit (B-1) is not particularly limited, and is 100 mol%. The constitutional unit B may be constituted only by the constitutional unit (B-1).

The constituent unit B may include constituent units other than the constituent unit (B-1). The diamine providing such a structural unit is not particularly limited, and examples thereof include 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-diaminodiphenylphosphonium, 4,4'-diaminobenzylamine benzene, 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) p-xylylenediamine, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4- Aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, and 9,9-bis (4-aminophenyl) fluorene And other aromatic diamines (except compounds represented by formula (b-1)); 1,3-bis (aminomethyl) cyclohexane and 1,4-bis (aminomethyl) cyclohexane, etc. Alicyclic diamines; and aliphatic diamines such as ethylenediamine and hexamethylenediamine.
In the present specification, the aromatic diamine means a diamine containing one or more aromatic rings, and the alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, and an aliphatic diamine. Refers to diamines that do not contain aromatic or alicyclic rings.
The constituent units other than the constituent unit (B-1) arbitrarily contained in the constituent unit B may be one type or two or more types.

In consideration of the mechanical strength of the obtained polyimide film, the number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 100,000. The number average molecular weight of the polyfluorene imine resin can be obtained, for example, by a standard polymethyl methacrylate (PMMA) conversion value obtained by measurement by gel filtration chromatography.

The polyfluorene imide resin of the present invention may include a structure other than a polyfluorene imine chain (a structure in which the structural unit A and the structural unit B are bonded by the fluorene imine). The structure other than the polyamidoimine chain which can be contained in a polyamidoimide resin is a structure containing a polyamido bond, etc., for example.
The polyfluorene imide resin of the present invention preferably contains a polyfluorene imine chain (a structure in which the structural unit A and the structural unit B are bonded by fluorene imine) as a main structure. Therefore, the ratio of the polyimide chain in the polyimide resin of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, more preferably 90% by mass or more, and most preferably 99% by mass. %the above.

By using the polyimide resin of the present invention, a thin film having excellent mechanical properties, heat resistance, colorless transparency, and low residual stress can be formed. The ideal physical properties of the film are shown below.

The tensile elastic coefficient is preferably 2.5 GPa or more, more preferably 3.0 GPa or more, and more preferably 3.5 GPa or more.
The tensile strength is preferably 100 MPa or more, more preferably 120 MPa or more, and more preferably 150 MPa or more.
The glass transition temperature (Tg) is preferably above 320 ° C, more preferably above 350 ° C, and even more preferably above 365 ° C.
When a film with a thickness of 10 μm is made, the total light transmittance is preferably 88% or more, more preferably 89% or more, and more preferably 90% or more.
When a film with a thickness of 10 μm is made, the yellow index (YI) is preferably 3.5 or less, more preferably 3.0 or less, and even more preferably 2.8 or less.
The residual stress is preferably 18.0 MPa or less, more preferably 17.0 MPa or less, and still more preferably 15.0 MPa or less.
Moreover, the said physical-property value in this invention can be specifically measured by the method as described in an Example.

[Manufacturing method of polyimide resin]
The polyimide resin of the present invention can contain a compound providing the above-mentioned constitutional unit (A-1) and a compound providing the above-mentioned constitutional unit (A-2) without containing a compound providing the above-mentioned constitutional unit (AX). The tetracarboxylic acid component is produced by reacting with a diamine component containing a compound providing the above-mentioned constituent unit (B-1).

As the compound providing the constituent unit (A-1), a compound represented by the formula (a-1) can be exemplified, but it is not limited thereto, and a derivative thereof may be used as long as the same constituent unit can be provided. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by the formula (a-1) (i.e., norbornane-2-spiro-α-cyclopentanone-α'-spiro-2 '' -Norbornane-5,5 '', 6,6 ''-tetracarboxylic acid), and alkyl esters of the tetracarboxylic acid. As a compound which provides a structural unit (A-1), the compound represented by Formula (a-1) (namely, dianhydride) is preferable.
Similarly, as the compound providing the constituent unit (A-2), a compound represented by the formula (a-2) may be mentioned, but it is not limited thereto, and a derivative thereof may be used as long as the same constituent unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by formula (a-2) and an alkyl ester of the tetracarboxylic acid. As a compound which provides a structural unit (A-2), the compound represented by Formula (a-2) (namely, dianhydride) is preferable.
In this invention, a tetracarboxylic-acid component does not contain the compound which provides a structural unit (AX). Therefore, the tetracarboxylic acid component does not include a compound represented by the formula (ax), nor does it include a derivative that can provide the same constituent unit. Examples of the derivative include a tetracarboxylic acid corresponding to a tetracarboxylic dianhydride represented by formula (ax) and an alkyl ester of the tetracarboxylic acid.

The tetracarboxylic acid component preferably contains 50 to 90 mole% of the compound providing the constituent unit (A-1), more preferably 55 to 85 mole%, and more preferably 60 to 80 mole%.
The tetracarboxylic acid component preferably contains 10 to 50 mol% of the compound providing the constituent unit (A-2), more preferably 15 to 45 mol%, and more preferably 20 to 40 mol%.
In the tetracarboxylic acid component, the total of the compound providing the constituent unit (A-1) and the compound providing the constituent unit (A-2) should preferably contain 50 mol% or more, more preferably 70 mol% or more, and more preferably Contains more than 90 mol%, especially more than 99 mol%. The upper limit of the total content of the compound providing the constituent unit (A-1) and the compound providing the constituent unit (A-2) is not particularly limited, and is 100 mol%. The tetracarboxylic acid component may be composed of only the compound providing the constituent unit (A-1) and the compound providing the constituent unit (A-2).

The tetracarboxylic acid component may contain a compound other than the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2) (except for the compound providing the structural unit (AX)). The above-mentioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic tetracarboxylic dianhydride, and their derivatives (tetracarboxylic acid, alkyl esters of tetracarboxylic acid, etc.) are listed.
The compound other than the compound providing the structural unit (A-1) and the compound providing the structural unit (A-2) arbitrarily contained in the tetracarboxylic acid component may be one type or two or more types.

As a compound which provides a structural unit (B-1), the compound represented by Formula (b-1) is mentioned, It is not limited to this, As long as the same structural unit can be provided, it can also be its derivative. Examples of the derivative include a diisocyanate corresponding to a diamine represented by the formula (b-1). As the compound providing the constituent unit (B-1), a compound represented by the formula (b-1) (that is, a diamine) is preferred.

The diamine component preferably contains more than 50 mole% of the compound providing the constituent unit (B-1), more preferably contains more than 70 mole%, more preferably contains more than 90 mole%, and more preferably contains more than 99 mole%. The upper limit of the content of the compound providing the constituent unit (B-1) is not particularly limited, that is, 100 mol%. The diamine component may be composed of only the compound that provides the constituent unit (B-1).

The diamine component may contain a compound other than the compound providing the constituent unit (B-1). Examples of the compound include the above-mentioned aromatic diamine, alicyclic diamine, and aliphatic diamine, and derivatives thereof ( Diisocyanate, etc.).
The compound other than the compound providing the structural unit (B-1) which is arbitrarily contained in the diamine component may be one kind or two or more kinds.

In the present invention, in terms of a feed amount ratio of a tetracarboxylic acid component to a diamine component used in the production of a polyimide resin, the diamine component is preferably 0.9 to 1.1 moles relative to 1 mole of the tetracarboxylic acid component. .

In addition, in the present invention, in addition to the tetracarboxylic acid component and the diamine component, a capping agent may be used in the production of the polyfluoreneimide resin. The capping agent is preferably a monoamine or a dicarboxylic acid. In terms of the amount of the introduced end-capping agent, it is preferably 0.0001 to 0.1 mol, and more preferably 0.001 to 0.06 mol relative to 1 mol of the tetracarboxylic acid component. As the monoamine-based capping agent, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, and 3-methylamine are recommended. Benzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline and the like. Among them, benzylamine and aniline are preferably used. As the dicarboxylic acid-based end-capping agent, dicarboxylic acids are preferred, and a part of them may be closed. Recommended examples are phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane- 1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and the like. Among them, phthalic acid and phthalic anhydride are preferably used.

The method for reacting the tetracarboxylic acid component and the diamine component is not particularly limited, and a known method can be used.
Specific reaction methods include: (1) feeding a tetracarboxylic acid component, a diamine component, and a reaction solvent to a reactor, stirring at room temperature to 80 ° C. for 0.5 to 30 hours, and then heating and performing 醯Method for imidization reaction; (2) Feed the diamine component and the reaction solvent into the reactor and dissolve them, and then feed the tetracarboxylic acid component. Stir for 0.5 to 30 hours at room temperature to 80 ° C if necessary. Then, a method of raising the temperature and performing the amidine imidization reaction; (3) a method of feeding a tetracarboxylic acid component, a diamine component, and a reaction solvent into the reactor, immediately raising the temperature and performing the amidine imidization reaction, and the like.

The reaction solvent used in the production of the polyfluorene imine resin is not limited as long as it does not interfere with the fluorene imine reaction and can dissolve the generated polyfluorene imine. Examples thereof include aprotic solvents, phenol-based solvents, ether-based solvents, and carbonate-based solvents.

Specific examples of the aprotic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-methylcaprolactone. Amidoamine solvents such as osmamine, 1,3-dimethylimidazolidinone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone; hexamethylphosphamide, hexamethyl Phosphonium triamine and other phosphorus-containing amine solvents; sulfur-containing solvents such as dimethyl hydrazone, dimethyl fluorene, and cyclobutane; ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone; Amine-based solvents such as methylpyridine and pyridine; ester-based solvents such as acetic acid (2-methoxy-1-methylethyl) and the like.

Specific examples of the phenol-based solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2, 6-xylenol, 3,4-xylenol, 3,5-xylenol and the like.
Specific examples of the ether-based solvent include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, and 1,2-bis (2-methoxyethoxy) ethane. , Bis [2- (2-methoxyethoxy) ethyl] ether, tetrahydrofuran, 1,4-dioxane and the like.
Specific examples of the carbonate-based solvent include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propyl carbonate.
Among the above-mentioned reaction solvents, a fluorene-based solvent or a lactone-based solvent is more preferable. Moreover, the said reaction solvent can be used individually or in mixture of 2 or more types.

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

In the fluorene imidization reaction, a known fluorene imidization catalyst can be used. Examples of the sulfonium imidization catalyst include an alkali catalyst and an acid catalyst.
Examples of the base catalyst include pyridine, quinoline, isoquinoline, α-methylpyridine, β-methylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, trimethylamine, triethylamine, and trimethylpyridine. Organic base catalysts such as propylamine, tributylamine, triethylenediamine, imidazole, N, N-dimethylaniline, N, N-diethylaniline; potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, Catalysts for inorganic bases such as potassium bicarbonate and sodium bicarbonate.
Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, and p-toluenesulfonic acid. Acid, naphthalenesulfonic acid, etc. The said sulfonium imidization catalyst can be used individually or in combination of 2 or more types.
Among the above, from the viewpoint of operability, it is preferable to use an alkali catalyst, an organic alkali catalyst is more suitable, and a triethylamine is more suitable, especially a combination of triethylamine and triethylenediamine is particularly preferable.

From the viewpoints of reaction rate and inhibition of gelation, the temperature of the imidization reaction is preferably 120 to 250 ° C, and more preferably 160 to 200 ° C. The reaction time is preferably 0.5 to 10 hours after the start of the distillation of the produced water.

[Polyimide varnish]
The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin of the present invention and an organic solvent, and the polyimide resin is dissolved in the organic solvent.
The organic solvent is not particularly limited as long as it can dissolve the polyfluorene imine resin, and it is preferable to use two or more kinds of the above-mentioned compounds as a reaction solvent for manufacturing the polyfluorene imine resin alone or in combination.
The polyimide varnish of the present invention may be a polyimide solution obtained by dissolving a polyimide resin obtained by a polymerization method in a reaction solvent, or a polyimide solution may be further diluted. Solvent derived.

Since the polyimide resin of the present invention has solvent solubility, it can be made into a high concentration varnish which is stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass of the polyimide resin of the present invention, and more preferably 10 to 30% by mass. The viscosity of polyimide varnish is preferably 1 to 200 Pa ･ s, and more preferably 5 to 150 Pa ･ s. The viscosity of the polyimide varnish is a value measured at 25 ° C using an E-type viscometer.
In addition, the polyimide varnish of the present invention may contain an inorganic filler, an adhesion promoter, a release agent, a flame retardant, an ultraviolet stabilizer, as long as the required characteristics of the polyimide film are not impaired. Surfactant, leveling agent, defoaming agent, fluorescent whitening agent, cross-linking agent, polymerization initiator, photosensitizer and other additives.
The manufacturing method of the polyimide varnish of this invention is not specifically limited, A well-known method can be used.

[Polyimide film]
The polyimide film of the present invention contains the polyimide resin of the present invention. Therefore, the polyimide film of the present invention is excellent in mechanical properties, heat resistance, and colorless transparency, and has low residual stress. The desirable physical properties of the polyimide film of the present invention are as described above.
The method for producing the polyfluorene imide film of the present invention is not particularly limited, and a known method can be used. For example, 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 formed into a thin film, and then the organic solvent such as a reaction solvent and a diluting solvent contained in the varnish is removed by heating. Methods, etc. The surface of the support may be coated with a release agent in advance if necessary.
As a method for removing the organic solvent contained in the varnish by heating, the following method is preferable. That is, after evaporating the organic solvent at a temperature of 120 ° C or lower to form a self-supporting film, the self-supporting film is peeled from the support, and the ends of the self-supporting film are fixed to use the organic solvent. The polyimide film is dried by drying at a temperature above the boiling point. Moreover, it is suitable to dry in a nitrogen environment. The pressure in the dry environment may be any of reduced pressure, normal pressure, and increased pressure. The heating temperature when the self-supporting film is dried to produce a polyfluorene film is not particularly limited, but is preferably 200 to 400 ° C.

The polyimide film of the present invention can also be produced by using a polyimide varnish obtained by dissolving polyamic acid in an organic solvent.
The polyamic acid contained in the aforementioned polyamic acid varnish is a precursor of the polyimide resin of the present invention, and includes a compound that provides the above-mentioned constituent unit (A-1) and a compound that provides the above-mentioned constituent unit (A-2). The compound does not contain a tetracarboxylic acid component of the compound providing the above-mentioned constituent unit (AX), and a product of addition polymerization reaction with a diamine component including the compound of the above-mentioned constituent unit (B-1). By subjecting the polyfluorenic acid to amidation (dehydration ring closure), the polyimide resin of the present invention as a final product can be obtained.
As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.
In the present invention, the polyamine varnish may be a compound containing the compound providing the above-mentioned constitutional unit (A-1) and the compound providing the above-mentioned constitutional unit (A-2) and not including the compound providing the above-mentioned constitutional unit (AX). The polyamic acid solution itself obtained by performing an addition polymerization reaction of a carboxylic acid component and a diamine component containing a compound providing the above-mentioned constituent unit (B-1) in a reaction solvent, or may be a polyamine solution It is obtained by adding a diluted solvent.

The method for producing a polyimide film using a polyamic acid varnish is not particularly limited, and a known method can be used. For example, polyamic acid varnish can be coated on a smooth support such as glass plate, metal plate, and plastic, or formed into a thin film, and then heated to remove the organic solvent such as the reaction solvent and dilution solvent contained in the varnish. A polyimide film is produced by heating and polyimide of the polyimide film in the polyimide film by heating.
The heating temperature when the polyamic acid varnish is dried to obtain a polyamino acid film is preferably 50 to 120 ° C. The heating temperature in the case where the polyamido acid is subjected to hydrazone imidation by heating is preferably 200 to 400 ° C.
In addition, the method of amidine imidization is not limited to hot amidine imidation, and chemical amidine imidization may also be used.

The thickness of the polyimide film of the present invention can be appropriately selected according to the application and the like, and is preferably 1 to 250 μm, more preferably 5 to 100 μm, and still more preferably 10 to 80 μm. With a thickness of 1 to 250 μm, it can be made into a self-supporting film and practically used.
The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish.

The polyimide film of the present invention can be preferably used as a film for various members such as color filters, flexible displays, semiconductor parts, and optical members. The polyimide film of the present invention is particularly preferably used as a substrate for an image display device such as a liquid crystal display or an OLED display.
[Example]

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited in any way by these examples.
The solid content concentrations of the varnishes obtained in the examples and comparative examples and the physical properties of the films were measured by the methods shown below.

(1) Solid content concentration The solid content concentration of the varnish is measured by using a small electric furnace "MMF-1" manufactured by AS ONE Co., Ltd. to heat the sample at 320 ° C for 120 min. Calculate the difference in quality.
(2) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd.
(3) Tensile modulus, tensile strength Tensile modulus and tensile strength are measured in accordance with JIS K7127 using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. The distance between the chucks was set to 10mm × 50mm, and the test speed was set to 20mm / min. The larger the coefficient of tensile elasticity and the tensile strength, the more excellent the value.
(4) Glass transition temperature (Tg)
The thermomechanical analyzer "TMA / SS6100" manufactured by Hitachi High-Tech Science Co., Ltd. was used in a tensile mode under the conditions of a sample size of 2 mm x 20 mm, a load of 0.1 N, and a temperature increase rate of 10 ° C / min to sufficiently heat The temperature of the residual stress is removed to remove the residual stress, and then it is cooled to room temperature. Then, the elongation of the test piece was measured under the same conditions as the aforementioned treatment for removing residual stress, and the inflection point at which the elongation was observed was defined as the glass transition temperature. The larger the Tg coefficient value, the more excellent.
(5) Total light transmittance, yellow index (YI)
The total light transmittance and YI are measured in accordance with JIS K7361-1: 1997 using a color and turbidity measuring device "COH400" manufactured by Nippon Denshoku Industries Co., Ltd. The better the total light transmittance is closer to 100%, and the smaller the YI coefficient value, the more excellent.
(6) Residual stress A 4-inch silicon wafer having a thickness of 525 μm ± 25 μm in which the “warpage amount” was measured in advance using a residual stress measuring device “FLX-2320” manufactured by KLA-Tencor, was coated with a polymer using a spin coater. Imine varnish or polyamic acid varnish, pre-baking. Then, a hot air dryer was used to perform a heat-hardening treatment at 400 ° C. for 1 hour in a nitrogen atmosphere to prepare a silicon wafer with a polyimide film having a thickness of 8 to 20 μm after curing. The residual stress measurement device was used to measure the warpage of the wafer, and the residual stress generated between the silicon wafer and the polyimide film was evaluated. The smaller the residual stress coefficient value, the better.

The tetracarboxylic acid components and diamine components used in the examples and comparative examples, and their abbreviations are as follows.
> Tetracarboxylic acid component>
CpODA: norbornane-2-spiro-α-cyclopentanone-α'-spiro-2 ''-norbornane-5,5 '', 6,6 ''-tetracarboxylic dianhydride (JXEnergy Limited) (Company; compound represented by formula (a-1))
BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation; compound represented by formula (a-2))
>Diamine>
TFMB: 2,2'-bis (trifluoromethyl) benzidine (manufactured by Wakayama Seika Chemical Co., Ltd .; compound represented by formula (b-1))

> Example 1>
32.024 g (0.100 mole) of a 1-liter 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen introduction tube, a Dean-Stark device equipped with a cooling tube, a thermometer, and a glass end cap TFMB and 82.391 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) were stirred at a rotation temperature of 150 rpm under a nitrogen temperature of 70 ° C. to obtain a solution.
To this solution, 30.750 g (0.080 mol) of CpODA, 5.884 g (0.020 mol) of BPDA, and 20.598 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) were added at one time, and then put into 0.506 g of triethylamine (manufactured by Kanto Chemical Co., Ltd.) of the imidization catalyst was heated with a mantle heater, and the temperature inside the reaction system was raised to 190 ° C. in about 20 minutes. The components obtained by distillation were collected, and the rotation speed was adjusted in accordance with the increase in viscosity, while the temperature in the reaction system was maintained at 190 ° C, and refluxed for 3 hours.
Thereafter, 482.505 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, and the temperature in the reaction system was cooled to 120 ° C., followed by stirring for about 3 hours to homogenize, and a solid content concentration of 10.0% by mass was obtained. Polyimide varnish.
Then, the obtained polyimide varnish was applied to a glass plate and a silicon wafer, and the heating plate was held at 80 ° C for 20 minutes. Thereafter, the solvent was heated at 400 ° C for 30 minutes in a hot air dryer under a nitrogen atmosphere to make the solvent. Evaporate to obtain a film with a thickness of 10 μm. The results are shown in Table 1.

> Example 2>
The amount of CpODA was changed from 30.750g (0.080 mol) to 23.063g (0.060 mol), and the amount of BPDA was changed from 5.884g (0.020 mol) to 11.769g (0.040 mol). A polyimide varnish was produced in the same manner as in Example 1. A polyimide varnish having a solid content concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced by the same method as in Example 1 to obtain a film having a thickness of 7 μm. The results are shown in Table 1.

> Comparative example 1>
The amount of CpODA was changed from 30.750 g (0.080 mol) to 38.438 g (0.100 mol) without adding BPDA. A polyimide varnish was produced in the same manner as in Example 1 to obtain a solid content. Polyimide varnish with a concentration of 10.0% by mass.
Using the obtained polyimide varnish, a film was produced by the same method as in Example 1 to obtain a film having a thickness of 14 μm. The results are shown in Table 1.

> Comparative example 2>
32.024 g (0.100 mole) of a 1-liter 5-necked round-bottomed flask equipped with a stainless steel half-moon stirring blade, a nitrogen introduction tube, a Dean-Stark device equipped with a cooling tube, a thermometer, and a glass end cap TFMB and 196.627 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) were stirred at a rotational speed of 150 rpm at a temperature of 50 ° C in a system to obtain a solution.
To this solution, 294.22 g (0.100 mol) of BPDA and 49.157 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) were added in one portion, and the mixture was stirred at 50 ° C. with a heating bag for 7 hour.
After that, 307.230 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) was added, and the mixture was stirred for about 3 hours to homogenize it to obtain a polyamic acid varnish having a solid content concentration of 10.0% by mass.
Then, the obtained polyamic acid varnish was coated on a glass plate and a silicon wafer, and the heating plate was held at 80 ° C for 20 minutes. Thereafter, the solvent was heated at 400 ° C for 30 minutes in a hot air dryer under a nitrogen atmosphere to make the solvent. Evaporation and further thermal imidization gave a film with a thickness of 12 μm. The results are shown in Table 1.

[Table 1]

As shown in Table 1, the polyimide films of Examples 1 and 2 were excellent in mechanical properties, heat resistance, and colorless transparency, and had low residual stress.
On the other hand, the polyimide film of Comparative Example 1 manufactured using only CpODA as a tetracarboxylic acid component has lower tensile elasticity coefficient and heat resistance than the polyimide films of Examples 1 and 2, and has residual stress. high. In addition, the polyimide film of Comparative Example 2 produced using only BPDA as a tetracarboxylic acid component has lower heat resistance, colorless transparency, and higher residual stress than the polyimide films of Examples 1 and 2.

Claims (5)

A polyfluorene imide resin having a constitutional unit A derived from a tetracarboxylic dianhydride and a constitutional unit B derived from a diamine, and the constitutional unit A includes a constitutional unit (A-1) derived from a compound represented by the following formula (a-1) And the constituent unit (A-2) derived from the compound represented by the following formula (a-2), the constituent unit B includes the constituent unit (B-1) derived from the compound represented by the following formula (b-1), and the constituent unit A does not contain Derived from the constituent unit (AX) of the compound represented by the following formula (ax), . For example, the polyimide resin of the scope of application for patent No. 1 wherein, The ratio of the constituent unit (A-1) in the constituent unit A is 50 to 90 mol%, The ratio of the structural unit (A-2) in the structural unit A is 10 to 50 mol%. For example, the polyimide resins in the scope of patent application No. 1 or 2, wherein: The ratio of the structural unit (B-1) in the structural unit B is 50 mol% or more. A polyimide varnish is obtained by dissolving a polyimide resin as described in any one of the claims 1 to 3 in an organic solvent. A polyimide film includes the polyimide resin according to any one of claims 1 to 3 of the scope of patent application.