WO2019198709A1

WO2019198709A1 - Polyimide resin, polyimide varnish and polyimide film

Info

Publication number: WO2019198709A1
Application number: PCT/JP2019/015454
Authority: WO
Inventors: 洋平安孫子; 慎司関口; 末永　修也
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2018-04-10
Filing date: 2019-04-09
Publication date: 2019-10-17
Also published as: CN111936554A; JP7371621B2; JPWO2019198709A1; TW201943766A; KR20200140823A; TWI804604B; CN111936554B

Abstract

The present invention provides a polyimide resin which comprises a constituent unit A that is derived from a tetracarboxylic acid dianhydride and a constituent unit B that is derived from a diamine, and which is configured such that: the constituent unit A contains a constituent unit (A-1) that is derived from a compound represented by formula (a-1) and a constituent unit (A-2) that is derived from a compound represented by formula (a-2); the constituent unit B contains a constituent unit (B-1) that is derived from a compound represented by formula (b-1); and the constituent unit A does not contain a constituent unit (A-X) that is derived from a compound represented by formula (a-x). The present invention also provides a polyimide varnish and a polyimide film, each of which contains this 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.

Generally, polyimide resins have excellent mechanical properties and heat resistance, and thus are being used in various fields such as electrical and electronic parts. For example, it is desired to replace a glass substrate used for an image display device such as a liquid crystal display or an OLED display with a plastic substrate for the purpose of reducing the weight or flexibility of the device. Research is ongoing. The polyimide film for such use is required to be colorless and transparent.

When a varnish applied on a glass support or a silicon wafer is heated and cured to form a polyimide film, residual stress is generated in the polyimide film. When the residual stress of the polyimide film is large, there arises a problem that the glass support or the silicon wafer is warped. Therefore, the polyimide film is also required to reduce the residual stress.
In Patent Document 1, 4,4′-oxydiphthalic dianhydride is used as a tetracarboxylic acid component as a polyimide resin that gives a film having low residual stress, and α, ω-aminopropyl poly (ethylene) having a number average molecular weight of 1000 is used as a diamine component. A polyimide resin synthesized using dimethylsiloxane and 4,4′-diaminodiphenyl ether is disclosed.

Japanese Patent Laid-Open No. 2005-232383

As described above, the polyimide film is required to have colorless transparency and low residual stress, but it is not easy to improve these characteristics while maintaining excellent mechanical properties and heat resistance.
The present invention has been made in view of such circumstances, and the object of the present invention is a polyimide resin that is excellent in mechanical properties, heat resistance, and colorless transparency, and can form a film with low residual stress, Another object is to provide a polyimide varnish and a polyimide film containing the polyimide resin.

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

That is, the present invention relates to the following [1] to [5].
[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-1) derived from the compound represented by the following formula (a-1) as the structural unit A and the structural unit (A-2) derived from the compound represented by the following formula (a-2) Including
The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1),
A polyimide resin in which the structural unit A does not include a structural unit (AX) derived from a compound represented by the following formula (ax).

[2]
The proportion of the structural unit (A-1) in the structural unit A is 50 to 90 mol%,
The polyimide resin according to [1] above, wherein the proportion of the structural unit (A-2) in the structural unit A is 10 to 50 mol%.
[3]
The polyimide resin according to the above [1] or [2], wherein the proportion of the structural unit (B-1) in the structural unit B is 50 mol% or more.
[4]
A polyimide varnish obtained by dissolving the polyimide resin according to any one of [1] to [3] above in an organic solvent.
[5]
A polyimide film comprising the polyimide resin according to any one of [1] to [3] above.

According to the present invention, it is possible to form a film having excellent mechanical properties, heat resistance, and colorless transparency, and having low residual stress.

[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 derived from a compound represented by the following formula (a-1). Including a structural unit (A-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2), wherein the structural unit B is represented by the following formula (b-1). The structural unit (B-1) derived from the compound is included, and the structural unit A does not include the structural unit (AX) derived from the compound represented by the following formula (ax).

<Structural unit A>
The structural unit A is a structural unit derived from tetracarboxylic dianhydride occupying the polyimide resin, the structural unit (A-1) derived from a compound represented by the following formula (a-1), and the following formula A structural unit (A-2) derived from the compound represented by (a-2), and a structural unit (AX) derived from the compound represented by the following formula (ax).

The compound represented by the formula (a-1) is norbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″ -norbornane-5,5 ″, 6,6 ″ -tetracarboxylic Acid dianhydride.

The compound represented by the formula (a-2) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3 ′, 4, represented by the following formula (a-2s): 4′-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a-2a), Examples thereof include 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride (i-BPDA) represented by the following formula (a-2i).

When the structural unit A includes both the structural unit (A-1) and the structural unit (A-2), the mechanical properties, heat resistance and colorless transparency of the film are improved, and the residual stress is decreased.

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

The ratio of the structural unit (A-1) in the structural 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 structural unit (A-2) in the structural 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 structural units (A-1) and (A-2) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more. And particularly preferably 99 mol% or more. The upper limit value of the total ratio of the structural units (A-1) and (A-2) is not particularly limited, that is, 100 mol%. The structural unit A may consist of only the structural unit (A-1) and the structural unit (A-2).

The structural unit A may include structural units other than the structural units (A-1) and (A-2) (except for the structural unit (AX)). The tetracarboxylic dianhydride that gives such a structural unit is not particularly limited, but pyromellitic dianhydride, 9,9′-bis (3,4-dicarboxyphenyl) fluorene dianhydride, and 4 , 4 ′-(Hexafluoroisopropylidene) diphthalic anhydride and other aromatic tetracarboxylic dianhydrides (excluding compounds represented by the formula (a-2)); 1,2,3,4- Cycloaliphatic tetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride (excluding compounds represented by formula (a-1) and compounds represented by formula (ax)); and 1 And aliphatic tetracarboxylic dianhydrides such as 2,3,4-butanetetracarboxylic dianhydride.
In this specification, an aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and an alicyclic tetracarboxylic dianhydride means one alicyclic ring. The tetracarboxylic dianhydride containing the above and containing no aromatic ring means an aliphatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.
The structural units other than the structural units (A-1) and (A-2) optionally contained in the structural unit A may be one type or two or more types.

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

The compound represented by the formula (b-1) is 2,2′-bis (trifluoromethyl) benzidine.
When the structural unit B contains the structural unit (B-1), the colorless transparency and heat resistance of the film are improved, and the residual stress is reduced.

The ratio of the structural unit (B-1) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably 99 mol%. % Or more. The upper limit value of the ratio of the structural unit (B-1) is not particularly limited, that is, 100 mol%. The structural unit B may consist of only the structural unit (B-1).

The structural unit B may include a structural unit other than the structural unit (B-1). The diamine which gives such a structural unit is not particularly limited, but 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, 1,5-diaminonaphthalene, 2,2′-dimethyl Biphenyl-4,4′-diamine, 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-indene-5-amine, α, α'-bis (4-aminophenyl) ) -1,4-diisopropylbenzene, N, N′-bis (4-aminophenyl) terephthalamide, 4,4′-bis (4-aminophenoxy) B) Biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, and 9,9-bis (4 -Aromatic diamines such as aminophenyl) fluorene (excluding compounds represented by formula (b-1)); 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, etc. And aliphatic diamines such as ethylenediamine and hexamethylenediamine.
In this specification, an aromatic diamine means a diamine containing one or more aromatic rings, an alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, A group diamine means a diamine containing neither an aromatic ring nor an alicyclic ring.
The number of structural units other than the structural unit (B-1) optionally included in the structural unit B may be one or more.

The number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 100,000 from the viewpoint of the mechanical strength of the resulting polyimide film. 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 a polyimide chain (a structure in which the structural unit A and the structural unit B are imide-bonded). Examples of the structure other than the polyimide chain that can be included in the polyimide resin include a structure including an amide bond.
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 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, still more preferably 90% by mass or more, and particularly preferably 99% by mass. % Or more.

By using the polyimide resin of the present invention, it is possible to form a film having excellent mechanical properties, heat resistance, and colorless transparency, and further having low residual stress, and suitable physical properties of the film are as follows. is there.

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

[Production method of polyimide resin]
The polyimide resin of the present invention contains the compound that gives the structural unit (A-1) and the compound that gives the structural unit (A-2), but does not contain the compound that gives the structural unit (AX). It can be produced by reacting a tetracarboxylic acid component with a diamine component containing a compound that gives the structural unit (B-1).

Examples of the compound that provides the structural unit (A-1) include compounds represented by the formula (a-1), but are not limited thereto, and may be derivatives thereof within a range that provides the same structural unit. Examples of the derivative include tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-1) (that is, norbornane-2-spiro-α-cyclopentanone-α′-spiro-2 ″). -Norbornane-5,5 ″, 6,6 ″ -tetracarboxylic acid), and alkyl esters of the tetracarboxylic acid. As the compound giving the structural unit (A-1), a compound represented by the formula (a-1) (that is, dianhydride) is preferable.
Similarly, examples of the compound that provides the structural unit (A-2) include compounds represented by the formula (a-2), but are not limited thereto and may be derivatives thereof within a range that provides the same structural unit. . Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a-2) and an alkyl ester of the tetracarboxylic acid. As the compound giving the structural unit (A-2), a compound represented by the formula (a-2) (that is, dianhydride) is preferable.
In the present invention, the tetracarboxylic acid component does not include a compound that provides the structural unit (AX). Therefore, the tetracarboxylic acid component does not include the compound represented by the formula (ax), and does not include the derivative as long as the same structural unit is provided. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (ax) and an alkyl ester of the tetracarboxylic acid.

The tetracarboxylic acid component preferably contains 50 to 90 mol%, more preferably 55 to 85 mol%, still more preferably 60 to 80 mol% of the compound that gives the structural unit (A-1).
The tetracarboxylic acid component preferably contains 10 to 50 mol%, more preferably 15 to 45 mol%, and still more preferably 20 to 40 mol% of the compound giving the structural unit (A-2).
The tetracarboxylic acid component contains, in total, a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2), preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably Contains 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the total content of the compound that provides the structural unit (A-1) and the compound that provides the structural unit (A-2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist only of a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2).

The tetracarboxylic acid component may contain a compound other than the compound that gives the structural unit (A-1) and the compound that gives the structural unit (A-2) (except for the compound that gives the structural unit (AX)). The compound includes the above-mentioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic acid, tetracarboxylic acid Alkyl ester etc.).
The compound other than the compound giving the structural unit (A-1) and the compound giving the structural unit (A-2) optionally contained in the tetracarboxylic acid component may be one kind or two or more kinds.

Examples of the compound that provides the structural unit (B-1) include compounds represented by the formula (b-1), but are not limited thereto, and may be derivatives thereof within a range that provides the same structural unit. Examples of the derivative include diisocyanates corresponding to the diamine represented by the formula (b-1). As the compound that gives the structural unit (B-1), a compound represented by the formula (b-1) (that is, a diamine) is preferable.

The diamine component preferably contains 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 99 mol% or more of the compound that gives the structural unit (B-1). . The upper limit of the content of the compound that gives the structural unit (B-1) is not particularly limited, that is, 100 mol%. The diamine component may consist only of a compound that provides the structural unit (B-1).

The diamine component may contain a compound other than the compound that gives the structural unit (B-1). Examples of the compound include the above-mentioned aromatic diamine, alicyclic diamine, and aliphatic diamine, and derivatives thereof (such as diisocyanate). Is mentioned.
The compound other than the compound that provides the structural unit (B-1) optionally contained in the diamine component may be one kind or two or more kinds.

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

In the present invention, for the production of the polyimide resin, a terminal blocking agent may be used in addition to the aforementioned tetracarboxylic acid component and diamine component. As end-capping agents, monoamines or dicarboxylic acids are preferred. The amount of the terminal blocking agent introduced is preferably 0.0001 to 0.1 mol, particularly preferably 0.001 to 0.06 mol, per 1 mol of the tetracarboxylic acid component. Examples of monoamine end-capping agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3- Ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline and the like are recommended. Of these, benzylamine and aniline can be preferably used. As the dicarboxylic acid end-capping agent, dicarboxylic acids are preferable, and a part of them may be closed. For example, 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 are recommended. Of these, phthalic acid and phthalic anhydride can be suitably used.

There is no restriction | limiting in particular in the method of making the above-mentioned tetracarboxylic acid component and a diamine component react, A well-known method can be used.
Specifically, (1) a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor, stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then heated to imidize. Method of performing the reaction, (2) The diamine component and the reaction solvent are charged into the reactor and dissolved, then the tetracarboxylic acid component is charged, and if necessary, stirred at room temperature to 80 ° C. for 0.5 to 30 hours, and then (3) A method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are charged into a reactor and the temperature is immediately raised to carry out an imidization reaction.

The reaction solvent used for the production of the polyimide resin may be any solvent that does not inhibit the imidization reaction and can dissolve the produced polyimide. For example, an aprotic solvent, a phenol solvent, an ether solvent, a carbonate solvent, and the like can be given.

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

Specific examples of the phenol 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 ether solvents include 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethyl]. Examples include ether, tetrahydrofuran, 1,4-dioxane and the like.
Specific examples of the carbonate solvent include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, and the like.
Among the above reaction solvents, amide solvents or lactone solvents are preferable. Moreover, you may use said reaction solvent individually or in mixture of 2 or more types.

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

In the above imidation reaction, a known imidation catalyst can be used. Examples of the imidization catalyst include a base catalyst and an acid catalyst.
Base catalysts include pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N, N -Organic base catalysts such as dimethylaniline and N, N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate.
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, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. Is mentioned. The above imidation catalysts may be used alone or in combination of two or more.
Among these, from the viewpoint of handleability, it is preferable to use a base catalyst, more preferably an organic base catalyst, still more preferably triethylamine, and particularly preferably a combination of triethylamine and triethylenediamine.

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

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

Since the polyimide resin of this invention has solvent solubility, it can be set as the high concentration varnish 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, more preferably 10 to 30% by mass. The viscosity of the polyimide varnish is preferably 1 to 200 Pa · s, 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 is an inorganic filler, adhesion promoter, release agent, flame retardant, UV stabilizer, surfactant, leveling agent, antifoaming agent, fluorescent enhancement, as long as the required properties of the polyimide film are not impaired. Various additives such as a whitening agent, a crosslinking agent, a polymerization initiator, and a photosensitizer may be included.
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 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 a low residual stress. The preferred physical properties 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 applying the polyimide varnish of the present invention on a smooth support such as a glass plate, a metal plate, or plastic, or forming it into a film, an organic solvent such as a reaction solvent or a diluting solvent contained in the varnish is used. The method of removing by heating, etc. are mentioned. If necessary, a release agent may be applied to the surface of the support in advance.
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 less to form 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 organic solvent used It is preferable to produce a polyimide film by drying at a temperature equal to or higher than the boiling point. Moreover, it is preferable to dry in nitrogen atmosphere. The pressure in the dry atmosphere may be any of reduced pressure, normal pressure, and increased pressure. The heating temperature for producing the polyimide film by drying the self-supporting film is not particularly limited, but is preferably 200 to 400 ° C.

Moreover, the polyimide film of this invention can also be manufactured using the polyamic-acid varnish formed by melt | dissolving a polyamic acid in the organic solvent.
The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, and includes a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2). And a product of a polyaddition reaction of a tetracarboxylic acid component not containing the compound giving the structural unit (AX) and a diamine component containing the compound giving the structural unit (B-1). By imidizing (dehydrating and ring-closing) this polyamic acid, the final product, the polyimide resin of the present invention, is obtained.
As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.
In the present invention, the polyamic acid varnish includes a compound that provides the structural unit (A-1) and a compound that provides the structural unit (A-2), and a compound that provides the structural unit (AX). It may be a polyamic acid solution itself obtained by polyaddition reaction of a tetracarboxylic acid component not contained and a diamine component containing the compound giving the structural unit (B-1) in a reaction solvent, or the polyamide What added the dilution solvent further with respect to an acid solution may be used.

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 coated on a smooth support such as a glass plate, a metal plate, or a plastic, or formed into a film, and an organic solvent such as a reaction solvent or a diluting solvent contained in the varnish is removed by heating. A polyimide film can be produced by obtaining a polyamic acid film and imidizing the polyamic acid in the polyamic acid film by heating.
The heating temperature for obtaining the polyamic acid film by drying the polyamic acid varnish is preferably 50 to 120 ° C. The heating temperature for imidizing the polyamic acid by heating is preferably 200 to 400 ° C.
The imidization method is not limited to thermal imidization, and chemical imidization can also be applied.

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

The polyimide film of the present invention is suitably used as a film for various members such as a color filter, a flexible display, a semiconductor component, and an optical member. The polyimide film of the present invention is particularly preferably used as a substrate for image display devices such as liquid crystal displays and OLED displays.

Hereinafter, the present invention will be described specifically by way of examples. However, this invention is not restrict | limited at all by these Examples.
The solid content concentration of the varnish obtained in Examples and Comparative Examples and the physical properties of the film were measured by the methods shown below.

(1) Solid content concentration The solid content concentration of the varnish was calculated from the difference in mass of the sample before and after heating by heating the sample at 320 ° C. × 120 min in a small electric furnace “MMF-1” manufactured by AS ONE Corporation.
(2) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Corporation.
(3) Tensile Elastic Modulus and Tensile Strength The tensile elastic modulus and tensile strength were measured using a tensile tester “Strograph VG-1E” manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127. The distance between chucks was 10 mm × 50 mm, and the test speed was 20 mm / min. Both the tensile modulus and tensile strength are better as the numerical value is larger.
(4) Glass transition temperature (Tg)
Residual stress is removed using the thermomechanical analyzer "TMA / SS6100" manufactured by Hitachi High-Tech Science Co., Ltd. under the conditions of sample size 2 mm x 20 mm, load 0.1 N, and heating rate 10 ° C / min. The temperature was raised to a sufficient temperature to remove residual stress, and then cooled to room temperature. Thereafter, the measurement of the elongation of the test piece was performed under the same conditions as the treatment for removing the residual stress, and the place where the inflection point of the elongation was observed was determined as the glass transition temperature. Tg is excellent as the numerical value increases.
(5) Total light transmittance, yellow index (YI)
The total light transmittance and YI were measured using a color / turbidity simultaneous measuring device “COH400” manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K7361-1: 1997. The closer the total light transmittance is to 100%, the better YI is.
(6) Residual stress A polyimide varnish was measured on a 4-inch silicon wafer having a thickness of 525 μm ± 25 μm, in which the “warping amount” was measured in advance using a residual stress measuring device “FLX-2320” manufactured by KLA-Tencor Corporation. Alternatively, polyamic acid varnish was applied using a spin coater and prebaked. Thereafter, using a hot air drier, a heat curing treatment was performed at 400 ° C. for 1 hour in a nitrogen atmosphere, and a silicon wafer with a polyimide film having a thickness of 8 to 20 μm after curing was produced. The amount of warpage of the wafer was measured using the above-described residual stress measuring device, and the residual stress generated between the silicon wafer and the polyimide film was evaluated. The smaller the numerical value, the better the residual stress.

The tetracarboxylic acid component and the diamine component used in 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 (manufactured by JX Energy Corporation; Compound represented by formula (a-1))
BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (Mitsubishi Chemical Corporation; compound represented by formula (a-2))
<Diamine>
TFMB: 2,2′-bis (trifluoromethyl) benzidine (Wakayama Seika Kogyo Co., Ltd .; compound represented by formula (b-1))

<Example 1>
32.024 g (0.100 mol) of TFMB in a 1 L 5-neck round bottom flask equipped with a stainless steel half-moon stirring blade, a Dean Stark fitted with a nitrogen inlet tube, a cooling tube, a thermometer, and a glass end cap And N-methylpyrrolidone (Mitsubishi Chemical Co., Ltd.) were added in an amount of 82.391 g, and the system temperature was 70 ° C. and a nitrogen atmosphere was stirred at a rotation speed of 150 rpm 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 all at once. Thereafter, 0.506 g of triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as an imidization catalyst and heated with a mantle heater, and the reaction system temperature was raised to 190 ° C. over about 20 minutes. The component to be distilled off was collected, and the temperature in the reaction system was maintained at 190 ° C. and refluxed for 3 hours while adjusting the number of rotations according to the increase in viscosity.
Thereafter, 482.505 g of γ-butyrolactone (Mitsubishi Chemical Co., Ltd.) was added and the reaction system internal temperature was cooled to 120 ° C., followed by further stirring for about 3 hours to homogenize and a solid content concentration of 10.0 mass. % Polyimide varnish was obtained.
Subsequently, the obtained polyimide varnish was applied to a silicon wafer on a glass plate, held at 80 ° C. for 20 minutes on a hot plate, and then heated at 400 ° C. in a hot air dryer for 30 minutes in a nitrogen atmosphere to evaporate the solvent. And a film having a thickness of 10 μm was obtained. The results are shown in Table 1.

<Example 2>
The amount of CpODA was changed from 30.750 g (0.080 mol) to 23.063 g (0.060 mol), and the amount of BPDA was changed from 5.884 g (0.020 mol) to 11.769 g (0.040 mol). Except for the above, a polyimide varnish was produced in the same manner as in Example 1 to obtain a polyimide varnish having a solid content concentration of 10.0% by mass.
Using the obtained polyimide varnish, a film was produced in the same manner 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), and a polyimide varnish was prepared in the same manner as in Example 1 except that BPDA was not added. A polyimide varnish having a solid content concentration of 10.0% by mass was obtained.
Using the obtained polyimide varnish, a film was produced in the same manner 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 mol) of TFMB in a 1 L 5-neck round bottom flask equipped with a stainless steel half-moon stirring blade, a Dean Stark fitted with a nitrogen inlet tube, a cooling tube, a thermometer, and a glass end cap And N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) were added in an amount of 196.627 g, and the mixture was stirred at a system temperature of 50 ° C. in a nitrogen atmosphere at a rotation speed of 150 rpm 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 Co., Ltd.) were added all at once and kept at 50 ° C. with a mantle heater for 7 hours. Stir.
Thereafter, 307.230 g of N-methylpyrrolidone (manufactured by Mitsubishi Chemical Corporation) was added, and further stirred for about 3 hours to homogenize to obtain a polyamic acid varnish having a solid content concentration of 10.0% by mass.
Subsequently, the obtained polyamic acid varnish is applied to a silicon wafer on a glass plate, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 400 ° C. for 30 minutes in a nitrogen atmosphere to remove the solvent. Evaporation and thermal imidization were performed to obtain a film having a thickness of 12 μm. The results are shown in 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 further had low residual stress.
On the other hand, the polyimide film of Comparative Example 1 produced using only CpODA as the tetracarboxylic acid component was inferior in tensile modulus and heat resistance and high in residual stress as compared with the polyimide films of Examples 1 and 2. . In addition, the polyimide film of Comparative Example 2 produced using only BPDA as the tetracarboxylic acid component was inferior in heat resistance and colorless transparency and high in residual stress as compared with the polyimide films of Examples 1 and 2. .

Claims

A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,
The structural unit (A-1) derived from the compound represented by the following formula (a-1) as the structural unit A and the structural unit (A-2) derived from the compound represented by the following formula (a-2) Including
The structural unit B includes a structural unit (B-1) derived from a compound represented by the following formula (b-1),
A polyimide resin in which the structural unit A does not include a structural unit (AX) derived from a compound represented by the following formula (ax).
The proportion of the structural unit (A-1) in the structural unit A is 50 to 90 mol%,
The polyimide resin according to claim 1, wherein the proportion of the structural unit (A-2) in the structural unit A is 10 to 50 mol%.
The polyimide resin according to claim 1 or 2, wherein the proportion of the structural unit (B-1) in the structural unit B is 50 mol% or more.
A polyimide varnish obtained by dissolving the polyimide resin according to any one of claims 1 to 3 in an organic solvent.
A polyimide film comprising the polyimide resin according to any one of claims 1 to 3.