WO2021177145A1

WO2021177145A1 - Polyimide resin, polyimide varnish, and polyimide film

Info

Publication number: WO2021177145A1
Application number: PCT/JP2021/007211
Authority: WO
Inventors: 洋平安孫子; 葵大東; 慎司関口
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2020-03-06
Filing date: 2021-02-25
Publication date: 2021-09-10
Also published as: TW202140620A; JPWO2021177145A1; CN115210292A; KR20220147092A

Abstract

A polyimide resin having a constituent unit A derived from a tetracarboxylic acid dianhydride and a constituent unit B derived from a diamine, wherein the constituent unit A includes a constituent unit (A1) derived from a compound represented by formula (a1) and a constituent unit (A2) derived from a compound represented by formula (a2), and the constituent unit B includes a constituent unit (B1) derived from a compound represented by formula (b1) and at least one constituent unit (B2) selected from the group consisting of a constituent unit (B21) derived from a compound represent by formula (b21) and a constituent unit (B22) derived from a compound represented by formula (b22).

Description

Polyimide resin, polyimide varnish and polyimide film

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

Various uses of polyimide resins are being studied in the fields of electrical and electronic components. For example, it is desired to replace a glass substrate used in an image display device such as a liquid crystal display or an OLED display with a plastic substrate for the purpose of reducing the weight and flexibility of the device. Research is underway.
Films used in image display devices are required to have various optical characteristics. For example, when light emitted from a display element is emitted through a plastic substrate, the plastic substrate is required to be colorless and transparent.

Polyimide resins with various compositions are being developed to satisfy the above performance. For example, Patent Document 1 contains 3,3 as diamine components for the purpose of obtaining a polyimide film having good solubility in a solvent and excellent processability, colorless and transparent, and excellent toughness. A polyimide film containing a structure consisting of a combination of'-diaminodiphenyl sulfone and other specific diamines is disclosed.

International Publication No. 2016/158825

In addition to colorless transparency, when used for applications where light passes through a retardation film or polarizing plate, for example, in a liquid crystal display, a touch panel, etc., the optical isotropic property is particularly high (that is, the Rth is low). Is required.
Further, a polyimide film having high chemical resistance is also required. For example, when a varnish for forming the resin layer is applied to the polyimide film in order to form another resin layer (for example, a color filter or a resist) on the polyimide film, the polyimide film contains a solvent contained in the varnish. Resistance to etc. is required. If the solvent resistance of the polyimide film is insufficient, it may become meaningless as a substrate due to dissolution or swelling of the film. However, as described above, in order to secure the optical properties, a solution must be used when producing the polyimide film, and it is difficult to achieve both of these properties.
Further, when the polyimide film is used as a substrate, there is a step of peeling the polyimide film from the support after creating the circuit. At that time, the polyimide film is required to have a certain toughness, that is, good elongation in order to facilitate the process and prevent breakage during peeling.
As described above, there has been a demand for a polyimide resin capable of obtaining a polyimide film having excellent elongation and chemical resistance while maintaining the optical characteristics of the obtained polyimide film, particularly optical isotropic property.

The present inventors have found that a polyimide resin containing a combination of a structural unit derived from two specific types of tetracarboxylic acid dianhydride and a structural unit derived from two specific types of diamine can solve the above-mentioned problems, and invented the invention. Has been completed.

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, wherein the structural unit A is a structural unit derived from a compound represented by the following formula (a1). (A1) and a structural unit (A2) derived from a compound represented by the following formula (a2) are included, and the structural unit B is a structural unit (B1) derived from a compound represented by the following formula (b1). A structural unit that is at least one selected from the group consisting of a structural unit (B21) derived from a compound represented by the following formula (b21) and a structural unit (B22) derived from a compound represented by the following formula (b22). Polyimide resin containing (B2).

<2> In the above <1>, the ratio of the constituent unit (A1) in the constituent unit A is 30 to 90 mol%, and the ratio of the constituent unit (A2) in the constituent unit B is 10 to 70 mol%. The polyimide resin described.
<3> The ratio of the constituent unit (B1) in the constituent unit B is 5 to 80 mol%, and the ratio of the constituent unit (B2) in the constituent unit B is 20 to 95 mol%. The polyimide resin according to <2>.
<4> A polyimide varnish in which the polyimide resin according to any one of <1> to <3> above is dissolved in an organic solvent.
<5> A polyimide film containing the polyimide resin according to any one of <1> to <3> above.

According to the present invention, a polyimide resin, a polyimide varnish, and a polyimide resin capable of forming a film having excellent optical isotropic properties and also excellent elongation and chemical resistance, and excellent optical isotropic properties and further elongation. It is possible to provide a polyimide film having excellent chemical resistance.

[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, and the structural unit A is a compound represented by the following formula (a1). A structural unit (A1) derived from the constituent unit (A1) and a structural unit (A2) derived from the compound represented by the following formula (a2), and the structural unit B derived from the compound represented by the following formula (b1) ( At least one selected from the group consisting of B1) and a structural unit (B21) derived from a compound represented by the following formula (b21) and a structural unit (B22) derived from a compound represented by the following formula (b22). Includes the structural unit (B2) that is.

The reason why the polyimide resin of the present invention is excellent in elongation and chemical resistance while maintaining optical isotropic property is not clear, but the alicyclic structure and the aromatic structure, and the ether structure and the sulfonyl structure are arranged in an appropriate ratio. Therefore, it is considered to be excellent in optical isotropic property, and also excellent in elongation and chemical resistance.

<Structural unit A>
The structural unit A is a structural unit derived from tetracarboxylic dianhydride in the polyimide resin.
The structural unit A includes a structural unit (A1) derived from the compound represented by the following formula (a1) and a structural unit (A2) derived from the compound represented by the following formula (a2).

The compound represented by the formula (a1) is a 4,4'-oxydiphthalic anhydride.
When the constituent unit A includes the constituent unit (A1), chemical resistance and elongation can be improved.
The compound represented by the formula (a2) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.
By including the structural unit (A2) in the structural unit A, it is possible to improve the transparency and optical isotropic property while increasing the solubility of the obtained polyimide resin in the varnish.

The ratio of the constituent unit (A1) in the constituent unit A is preferably 30 to 90 mol%, more preferably 35 to 70 mol%, and further preferably 40 to 60 mol%.
The ratio of the constituent unit (A2) in the constituent unit A is preferably 10 to 70 mol%, more preferably 30 to 65 mol%, and further preferably 40 to 60 mol%.
The total ratio of the constituent units (A1) and (A2) in the constituent unit A is preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably 90 mol% or more. The upper limit is not particularly limited, and the total ratio of the constituent units (A1) and (A2) in the constituent unit A 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 unit (A1) and the structural unit (A2) in the structural unit A is preferably 30/70 from the viewpoint of improving optical isotropic property and chemical resistance. It is ~ 90/10, more preferably 35/65 to 70/30, and even more preferably 40/60 to 60/40.

The structural unit A may include a structural unit other than the structural unit (A1) and the structural unit (A2). The tetracarboxylic dianhydride giving such a constituent unit is not particularly limited, but is pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 9,9'. -Bis (3,4-dicarboxyphenyl) fluorene dianhydride, and aromatic tetracarboxylic dianhydrides such as 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride (provided in the formula (a1)). (Excluding the compounds represented); 1,2,3,4-cyclobutanetetracarboxylic dianhydride, norbornenan-2-spirio-α-cyclopentanone-α'-spirio-2''-norbornane-5,5 '', 6,6''-tetracarboxylic dianhydride, 5,5'-bis-2-norbornene-5,5', 6,6'-tetracarboxylic acid-5,5', 6,6' -Alicyclic tetracarboxylic dianhydride such as dianhydride (excluding the compound represented by the formula (a2)); and fat such as 1,2,3,4-butanetetracarboxylic dianhydride Examples thereof include group tetracarboxylic dianhydride.
In the present specification, the aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, and the alicyclic tetracarboxylic dianhydride has one alicyclic ring. It means a tetracarboxylic acid dianhydride containing the above and does not contain an aromatic ring, and the aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride containing neither an aromatic ring nor an alicyclic ring.
The structural unit arbitrarily included in the structural unit A may be one type or two or more types.

<Structural unit B>
The structural unit B is a structural unit derived from diamine in the polyimide resin.
The structural unit B is a structural unit (B1) derived from the compound represented by the following formula (b1), a structural unit (B21) derived from the compound represented by the following formula (b21), and the following formula (b22). It contains at least one structural unit (B2) selected from the group consisting of structural units (B22) derived from the represented compound.

The compound represented by the formula (b1) is a bis [(aminophenoxy) phenyl] sulfone, and as a specific example, a bis [4- (4-aminophenoxy) phenyl] sulfone represented by the following formula (b1a). , A bis [4- (3-aminophenoxy) phenyl] sulfone represented by the following formula (b1b). When the structural unit B includes the structural unit (B1), the elongation and chemical resistance of the film can be improved, and the heat resistance and optical anisotropy can also be improved.

The compound represented by the formula (b21) is bis (aminomethyl) cyclohexane, and specific examples thereof include 1,3-bis (aminomethyl) cyclohexane represented by the following formula (b21a) and the following formula (b21b). ), And 1,4-bis (aminomethyl) cyclohexane is mentioned.

The cis: trans ratio of the compound represented by the formula (b21) is preferably 0: 100 to 80:20, more preferably 0.1: 99.9 to 70:30, from the viewpoint of organic solvent resistance and heat resistance. Preferably, 0.5: 99.5 to 60:40 is even more preferable, and 1:99 to 20:80 is even more preferable.

The compound represented by the formula (b22) is bis (aminomethyl) norbornane. The formula (b22) represents an isomer mixture, and the compound represented by the formula (b22) is available as an isomer mixture.
By including the structural unit (B2) in the structural unit B, the transparency and optical isotropic property of the film can be improved.

The ratio of the constituent unit (B1) in the constituent unit B is preferably 5 to 80 mol%, more preferably 10 to 70 mol%, and further preferably 30 to 60 mol%.
The ratio of the constituent unit (B2) in the constituent unit B is preferably 20 to 95 mol%, more preferably 30 to 90 mol%, and further preferably 40 to 70 mol%.
The total ratio of the constituent units (B1) and (B2) in the constituent unit B is preferably 50 mol% or more, more preferably 70 mol% or more, and further preferably 90 mol% or more. The upper limit is not particularly limited, and the total ratio of the constituent units (B1) and (B2) in the constituent unit B is 100 mol% or less. The structural unit B may consist only of the structural unit (B1) and the structural unit (B2).
The molar ratio [(B1) / (B2)] of the structural unit (B1) to the structural unit (B2) in the structural unit B is preferably 5/95 from the viewpoint of improving optical isotropic property and chemical resistance. It is -80/20, more preferably 10/90 to 70/30, and even more preferably 30/70 to 60/40. Further, from the viewpoint of heat resistance and elongation, it is preferably 25/75 to 80/20, more preferably 35/65 to 65/35, still more preferably 35/65 to 55/45, and further preferably. Is 35/65 to 45/55.

The structural unit B may include a structural unit other than the structural unit (B1) and the structural unit (B2). The diamine giving such a constituent unit is not particularly limited, but is limited to 1,4-phenylenediamine, p-xylylene diamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine. , 4,4'-Diaminodiphenyl ether, 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether, 4,4'-diaminodiphenylmethane, 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'-bis (4-aminophenyl) terephthalamide, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (4-amino) Aromatic amines such as phenoxy) phenyl] propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, and 9,9-bis (4-aminophenyl) fluorene (where the formula (b1) ); Alicyclic diamines (excluding compounds represented by formula (b21) and compounds represented by formula (b22)); and aliphatics such as ethylenediamine and hexamethylenediamine. Diamine is mentioned.
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 not containing an aromatic ring, and is a fat. The group diamine means a diamine that does not contain an aromatic ring or an alicyclic ring.
The structural unit arbitrarily included in the structural unit B may be one type or two or more types.

<Characteristics of polyimide resin>
The weight average molecular weight of the polyimide resin is preferably 5,000 to 300,000 from the viewpoint of the mechanical strength of the obtained polyimide film. The weight average molecular weight of the polyimide resin can be determined from, for example, a standard polymethylmethacrylate (PMMA) conversion value measured by gel filtration chromatography.

The polyimide resin may contain a structure other than the polyimide chain (a structure in which the structural unit A and the structural unit B are imide-bonded). Examples of the structure other than the polyimide chain that can be contained in the polyimide resin include a structure containing an amide bond.
The polyimide resin 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 to the polyimide resin is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 99% by mass or more. Yes, and less than 100 mol%. The polyimide resin may consist only of a polyimide chain.

The polyimide resin composition of the present invention containing the above-mentioned polyimide resin can form a film excellent in optical isotropic property, elongation and chemical resistance, and suitable physical property values of the film are as follows.

The total light transmittance is preferably 88% or more, more preferably 88.5% or more, and further preferably 89% or more when the film has a thickness of 10 μm.
The yellow index (YI) is preferably 5.0 or less, more preferably 3.0 or less, still more preferably 2.5 or less, and even more preferably, when the film has a thickness of 10 μm. It is 2.0 or less.
The absolute value of the thickness retardation (Rth) is preferably 70 nm or less, more preferably 50 nm or less, still more preferably 35 nm or less, still more preferably 30 nm or less, and more when the film has a thickness of 10 μm. More preferably, it is 20 nm or less.

Further, the film that can be formed by using the above-mentioned polyimide resin has good mechanical properties and heat resistance, and has the following suitable physical property values.
The tensile strength is preferably 70 MPa or more, more preferably 90 MPa or more, and further preferably 100 MPa or more.
The tensile elastic modulus is preferably 1.5 GPa or more, more preferably 2.0 GPa or more, still more preferably 2.5 GPa or more, still more preferably 2.7 GPa or more.
The tensile elongation at break is preferably 8% or more, more preferably 10% or more, still more preferably 15% or more, still more preferably 20% or more.
The glass transition temperature (Tg) is preferably 200 ° C. or higher, more preferably 230 ° C. or higher, and even more preferably 250 ° C. or higher.
The above-mentioned physical property values in the present invention can be specifically measured by the method described in Examples.

<Manufacturing method of polyimide resin>
The polyimide resin of the present invention comprises a tetracarboxylic acid component containing a compound giving the above-mentioned structural unit (A1) and a compound giving the above-mentioned structural unit (A2), a compound giving the above-mentioned structural unit (B1), and the above-mentioned configuration. It can be produced by reacting with a diamine component containing a compound giving a unit (B2).

Examples of the compound giving the structural unit (A1) include the compound represented by the formula (a1), but the compound is not limited to this, and may be a derivative thereof as long as the same structural unit is given. Examples of the derivative include a tetracarboxylic acid (that is, 4,4'-oxydiphthalic acid) corresponding to the tetracarboxylic dianhydride represented by the formula (a1), and an alkyl ester of the tetracarboxylic acid. Of these, the tetracarboxylic dianhydride represented by the formula (a1) is preferable.
Similarly, the compound giving the structural unit (A2) includes a compound represented by the formula (a2), but the compound is not limited to this, and may be a derivative thereof as long as the same structural unit is given. Examples of the derivative include a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by the formula (a2) (that is, 1,2,4,5-cyclohexanetetracarboxylic acid), and an alkyl ester of the tetracarboxylic acid. Can be mentioned. Of these, the tetracarboxylic dianhydride represented by the formula (a2) is preferable.

The tetracarboxylic acid component preferably contains the compound giving the structural unit (A1) in an amount of 30 to 90 mol%, more preferably 35 to 70 mol%, still more preferably 40 to 60 mol%.
The tetracarboxylic acid component preferably contains the compound giving the structural unit (A2) in an amount of 10 to 70 mol%, more preferably 30 to 65 mol%, and further preferably 40 to 60 mol%.
The tetracarboxylic acid component contains, in total, a compound giving the constituent unit (A1) and a compound giving the constituent unit (A2) in an amount of preferably 50 mol% or more, more preferably 70 mol% or more, and more preferably 90 mol%. Including the above. The upper limit is not particularly limited, and the total amount of the tetracarboxylic acid component is 100 mol% or less of the compound giving the constituent unit (A1) and the compound giving the constituent unit (A2). The tetracarboxylic acid component may consist only of a compound that gives a constituent unit (A1) and a compound that gives a constituent unit (A2).
The molar ratio [(A1) / (A2)] of the compound giving the constituent unit (A1) to the compound giving the constituent unit (A2) in the tetracarboxylic acid component is preferably 30/70 to 90/10, and more. It is preferably 35/65 to 70/30, and more preferably 40/60 to 60/40.

The tetracarboxylic acid component may contain any compound other than the compound giving the structural unit (A1) and the compound giving the structural unit (A2).
Such optional compounds include the above-mentioned aromatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, and aliphatic tetracarboxylic dianhydrides, and derivatives thereof (tetracarboxylic acid, tetra). Alkyl ester of carboxylic acid, etc.).
The compound arbitrarily contained in the tetracarboxylic acid component may be one kind or two or more kinds.

Examples of the compound giving the structural unit (B1) include the compound represented by the formula (b1), but the compound is not limited to this, and may be a derivative thereof as long as the same structural unit is given. Examples of the derivative include diisocyanates corresponding to the compound represented by the formula (b1). As the compound that gives the structural unit (B1), the compound represented by the formula (b1) (that is, a diamine) is preferable.
Similarly, examples of the compound that gives the structural unit (B2) include, but are not limited to, the compound represented by the formula (b21) and the compound represented by the formula (b22), as long as the same structural unit is given. It may be a derivative. Examples of the derivative include a diisocyanate corresponding to the compound represented by the formula (b21) and a diisocyanate corresponding to the compound represented by the formula (b22). As the compound giving the structural unit (B2), a compound represented by the formula (b21) and a compound represented by the formula (b22) (that is, a diamine) are preferable.

The diamine component preferably contains 5 to 80 mol%, more preferably 10 to 70 mol%, and further preferably 30 to 60 mol% of the compound giving the structural unit (B1).
The diamine component preferably contains a compound that gives the structural unit (B2) in an amount of 20 to 95 mol%, more preferably 30 to 90 mol%, and even more preferably 40 to 70 mol%.
The diamine component contains, in total, a compound that gives the constituent unit (B1) and a compound that gives the constituent unit (B2), preferably 50 mol% or more, more preferably 70 mol% or more, and more preferably 90 mol% or more. .. The upper limit is not particularly limited, and the total amount of the tetracarboxylic acid component is 100 mol% or less of the compound giving the constituent unit (B1) and the compound giving the constituent unit (B2). The tetracarboxylic acid component may consist only of a compound that gives a constituent unit (B1) and a compound that gives a constituent unit (B2).
The molar ratio [(B1) / (B2)] of the compound giving the constituent unit (B1) to the compound giving the constituent unit (B2) in the diamine component is determined from the viewpoint of improving optical isotropic property and chemical resistance. It is preferably 5/95 to 80/20, more preferably 10/90 to 70/30, and even more preferably 30/70 to 60/40. Further, from the viewpoint of heat resistance and elongation, it is preferably 25/75 to 80/20, more preferably 35/65 to 65/35, still more preferably 35/65 to 55/45, and further preferably. Is 35/65 to 45/55.

The diamine component may contain any compound other than the compound giving the structural unit (B1) and the compound giving the structural unit (B2).
Such arbitrary compounds include the above-mentioned aromatic diamines, alicyclic diamines, and aliphatic diamines, and derivatives thereof (diisocyanates, etc.).
The compound arbitrarily contained in the diamine component may be one kind or two or more kinds.

In the production of the polyimide resin of the present invention, the charge amount ratio of the tetracarboxylic acid component and the diamine component used in the production of the polyimide resin is 0.9 to 1.1 mol of the diamine component with respect to 1 mol of the tetracarboxylic acid component. Is preferable.

Further, in the production of the polyimide resin of the present invention, an end-capping agent may be used in the production of the polyimide resin in addition to the above-mentioned tetracarboxylic acid component and diamine component. As the terminal encapsulant, monoamines or dicarboxylic acids are preferable. The amount of the terminal encapsulant to be introduced is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, based on 1 mol of the tetracarboxylic acid component. Examples of the monoamine terminal encapsulant include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-. Examples thereof include ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, and benzylamine and aniline are preferable. As the dicarboxylic acid terminal encapsulant, dicarboxylic acids are preferable, and a part thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2 Examples thereof include -dicarboxylic acid and 4-cyclohexene-1,2-dicarboxylic acid, and phthalic acid and phthalic anhydride are preferable.

The method for reacting the above-mentioned tetracarboxylic acid component with the diamine component is not particularly limited, and a known method can be used.
Specific reaction methods include (1) charging 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 imidize. Method of carrying out the reaction, (2) After charging the diamine component and the reaction solvent into the reactor and dissolving them, the tetracarboxylic acid component is charged, and if necessary, the mixture is stirred at 10 to 110 ° C. for 0.5 to 30 hours, and then. Examples thereof include a method of carrying out an imidization reaction by raising the temperature to (3) a method of charging a tetracarboxylic acid component, a diamine component and a reaction solvent into a reactor and immediately raising the temperature to carry out the imidization reaction.

The reaction solvent used in the production of the polyimide resin may be one 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 mentioned.

Specific examples of the aprotonic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), N-methylcaprolactam, 1,3-dimethylimidazolidinone, and tetra. Amide solvents such as methyl urea, lactone solvents such as γ-butyrolactone (GBL) and γ-valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphintriamide, dimethyl sulfone and dimethyl sulfoxide. , Sulfur-containing solvent such as sulfolane, ketone solvent such as acetone, cyclohexanone, methylcyclohexanone, amine solvent such as picolin and pyridine, ester solvent such as acetic acid (2-methoxy-1-methylethyl) and the like. ..

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

In the imidization 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 imidization rate can be further increased.

In the above imidization reaction, a known imidization 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 (TEA), tripropylamine, tributylamine, triethylenediamine, imidazole, Examples thereof include organic base catalysts such as 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.
Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, paratoluenesulfonic acid, naphthalenesulfonic acid and the like. Can be mentioned. The above-mentioned imidization catalyst may be used alone or in combination of two or more.
Of the above, from the viewpoint of handleability, it is preferable to use a base catalyst, more preferably an organic base catalyst, and even more preferably triethylamine.

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 may be any one that dissolves the polyimide resin, and is not particularly limited, but it is preferable to use the above-mentioned compounds alone or in combination of two or more as the reaction solvent used for producing the polyimide resin.
The polyimide varnish of the present invention may be the polyimide solution itself in which the polyimide resin obtained by the polymerization method is dissolved in a reaction solvent, or may be diluted by adding a solvent to the polyimide solution. good.

Since the polyimide resin of the present invention has solvent solubility, it is possible to obtain a high-concentration varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains the polyimide resin of the present invention in an amount of 5 to 40% by mass, more preferably 5 to 20% by mass. The viscosity of the polyimide varnish is preferably 1 to 200 Pa · s, more preferably 1 to 100 Pa · s. The viscosity of the polyimide varnish is a value measured at 25 ° C. using an E-type viscometer.
Further, the polyimide varnish of the present invention has an inorganic filler, an adhesion accelerator, a release agent, a flame retardant, an ultraviolet stabilizer, a surfactant, a leveling agent, a defoaming agent, and an optical brightener as long as the required properties of the polyimide film are not impaired. Various additives such as a whitening agent, a cross-linking agent, a polymerization initiator, and a photosensitizer may be contained.
The method for producing the polyimide varnish of the present invention is not particularly limited, and a known method can be applied.

[Polyimide film]
The polyimide film of the present invention contains the polyimide resin of the present invention. Therefore, the polyimide film of the present invention is excellent in optical isotropic property, peelability and chemical resistance. Suitable physical property values of the polyimide film of the present invention are as described above as <property of polyimide resin>.
The method for producing the polyimide 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 applied onto a smooth support such as a glass plate, a metal plate, or plastic, or formed into a film, and then an organic solvent such as a reaction solvent or a dilution solvent contained in the varnish is applied. Examples thereof include a method of removing by heating.

Examples of the coating method include known coating methods such as spin coating, slit coating, and blade coating, and spin coating and slit coating are preferable. Above all, the slit coat is more preferable from the viewpoint of controlling the intermolecular orientation and improving the chemical resistance and workability.
As a method for removing the organic solvent contained in the varnish by heating, the organic solvent is evaporated at a temperature of 150 ° C. or lower to make it tack-free, and then the temperature is equal to or higher than the boiling point of the organic solvent used (not particularly limited, but preferably). It is preferable to dry at 200 to 500 ° C.). Further, it is preferable to dry in an air atmosphere or a nitrogen atmosphere. The pressure in the dry atmosphere may be reduced pressure, normal pressure, or pressurized.
The method of peeling the polyimide film formed on the support from the support is not particularly limited, but a mechanical peel-off method, a laser lift-off method, or the like can be used.

Further, the polyimide film of the present invention can also be produced by using a polyamic acid varnish in which polyamic acid is dissolved in an organic solvent.
The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, and is a tetracarboxylic acid component containing a compound giving the above-mentioned structural unit (A1) and a compound giving the above-mentioned structural unit (A2). And the product of the polyaddition reaction between the compound giving the above-mentioned structural unit (B1) and the diamine component containing the compound giving the structural unit (B2). By imidizing (dehydrating and ring-closing) this polyamic acid, the polyimide resin of the present invention, which is the 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 production of the polyimide film of the present invention, the polyamic acid varnish may be the polyamic acid solution itself obtained by subjecting the tetracarboxylic acid component and the diamine component to a heavy addition reaction in a reaction solvent, or the polyamic acid solution. It may be diluted by adding a solvent to the above.

The method for producing the polyimide film using the polyamic acid varnish is not particularly limited, and a known method can be used. For example, a polyamic acid varnish is applied onto a smooth support such as a glass plate, a metal plate, or plastic, or formed into a film, and organic solvents such as a reaction solvent and a diluting solvent contained in the varnish are removed by heating. A polyimide film can be produced by obtaining a polyamic acid film and imidizing the polyamic acid in the polyamic acid film by heating.
The heating temperature for drying the polyamic acid varnish to obtain a polyamic acid film 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 intended use, but is preferably 1 to 250 μm, more preferably 5 to 100 μm, still more preferably 8 to 80 μm, still more preferably 10 to 80 μm. The range. When the thickness is 1 to 250 μm, it can be practically used as a self-supporting film.
The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and the viscosity of the polyimide varnish.

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

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to these examples.

<Film physical characteristics and evaluation>
The physical characteristics of the films obtained in 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 Co., Ltd.

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

(3) Glass transition temperature (Tg)
Using the thermomechanical analyzer "TMA / SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., residual stress is removed under the conditions of sample size 2 mm x 20 mm, load 0.1 N, and heating rate 10 ° C / min in tensile mode. The temperature was raised to a sufficient temperature to remove residual stress, and then cooled to room temperature. Then, the elongation of the test piece was measured 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.

(4) Total light transmittance and yellow index (YI)
The total light transmittance and YI were measured using a color / turbidity simultaneous measuring device "COH7700" manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7136.

(5) The haze measurement was carried out in accordance with JIS K7361-1 using a color / turbidity simultaneous measuring device "COH7700" manufactured by Nippon Denshoku Industries Co., Ltd.

(6) Thickness phase difference (Rth) (evaluation of optical isotropic property)
The thickness phase difference (Rth) was measured using an ellipsometer "M-220" manufactured by JASCO Corporation. The value of the thickness phase difference at the measurement wavelength of 590 nm was measured. Rth is expressed by the following formula, where nx is the maximum in-plane refractive index of the polyimide film, ny is the minimum, nz is the refractive index in the thickness direction, and d is the thickness of the film. Is to be done.
Rth = [{(nx + ny) / 2} -nz] × d
The 10 μm-converted Rth is Rth when the value of d is 10 μm.

(7) Solvent resistance (PGMEA resistance) (evaluation of chemical resistance)
The polyimide film formed on the glass plate was immersed in a solvent at room temperature, and it was confirmed whether the film surface was changed. As the solvent, propylene glycol monomethyl ether acetate (PGMEA) was used.
The evaluation criteria for solvent resistance were as follows.
A: There was no change on the film surface.
B: The film surface was cracked or the film surface was melted.

<Abbreviations for ingredients, etc.>
The tetracarboxylic acid component and diamine component used in Examples and Comparative Examples, and their abbreviations are as follows.

(Tetracarboxylic acid component)
ODPA: 4,4'-oxydiphthalic anhydride (manufactured by Manac Inc .; compound represented by formula (a1))
HPMDA: 1,2,4,5-Cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (a2))

(Diamine component)
BAPS: Bis [4- (4-aminophenoxy) phenyl] sulfone (manufactured by Seika Co., Ltd .; compound represented by formula (b1a))
M-BAPS: Bis [4- (3-aminophenoxy) phenyl] sulfone (manufactured by Seika Co., Ltd .; compound represented by the formula (b1b))
1,3-BAC: 1,3-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (b21a))
1,4-BAC: 1,4-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (b21b); trans ratio 40%)
1,4-BACT: 1,4-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (b21b); trans ratio 85%)
3,3'-DDS: 3,3'-diaminodiphenyl sulfone (manufactured by Seika Co., Ltd.)

<Manufacturing of polyimide resin, varnish and polyimide film>
Example 1
BAPS 8.650 g (0.020 mol) in a 500 mL 5-necked round-bottom flask equipped with a stainless steel crescent-shaped stirring blade, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. , 1,4-BACT 11.380 g (0.080 mol) and γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) 45.710 g were added, and the mixture was stirred at a system temperature of 70 ° C., a nitrogen atmosphere, and a rotation speed of 150 rpm. Obtained a solution.
To this solution, 15.511 g (0.050 mol) of ODPA, 11.209 g (0.050 mol) of HPMDA, and 11.427 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Inc.) were added in a batch and then imidized. 0.506 g of triethylamine (manufactured by Kanto Chemical Co., Inc.) was added as a catalyst and heated with a mantle heater to raise the temperature inside the reaction system to 190 ° C. over about 20 minutes. The components to be distilled off were collected, and the temperature inside the reaction system was maintained at 190 ° C. and refluxed for 2 hours while adjusting the rotation speed according to the increase in viscosity.
Then, 187.350 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 15% by mass, the temperature inside the reaction system was cooled to 100 ° C., and the mixture was further stirred for about 1 hour to make it uniform. To obtain a polyimide varnish.
Subsequently, the obtained polyimide varnish was applied onto a glass plate by spin coating, held on a hot plate at 80 ° C. for 20 minutes, and then heated in a hot air dryer at 260 ° C. for 30 minutes in an air atmosphere to prepare a solvent. Evaporation gave a film.

Example 2
The amount of 1,4-BACT was changed from 11.380 g (0.080 mol) to 9.958 g (0.070 mol), and the amount of BAPS was changed from 8.650 g (0.020 mol) to 12.975 g (0). A polyimide varnish having a solid content concentration of 15% by mass was obtained by the same method as in Example 1 except that the mixture was changed to .030 mol).
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 3
The amount of 1,4-BACT was changed from 11.380 g (0.080 mol) to 8.535 g (0.060 mol), and the amount of BAPS was changed from 8.650 g (0.020 mol) to 17.300 g (0). A polyimide varnish having a solid content concentration of 15% by mass was obtained by the same method as in Example 1 except that the mixture was changed to .040 mol).
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 4
The amount of 1,4-BACT was changed from 11.380 g (0.080 mol) to 7.113 g (0.050 mol), and the amount of BAPS was changed from 8.650 g (0.020 mol) to 21.625 g (0). A polyimide varnish having a solid content concentration of 15% by mass was obtained by the same method as in Example 1 except that the mixture was changed to .050 mol).
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 5
Solid content concentration 15% by mass by the same method as in Example 4 except that 1,4-BACT 7.13 g (0.050 mol) was changed to 1,4-BAC 7.113 g (0.050 mol). Polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 6
Solid content concentration 15% by mass by the same method as in Example 4 except that 1,4-BACT 7.13 g (0.050 mol) was changed to 1,3-BAC 7.113 g (0.050 mol). Polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 7
7.113 g (0.050 mol) of 1,4-BACT is added to bis (aminomethyl) norbornan (isomer mixture: manufactured by Tokyo Chemical Industry Co., Ltd .; compound represented by formula (b22)) 7.713 g (0.050). A polyimide varnish having a solid content concentration of 15% by mass was obtained by the same method as in Example 4 except that the mixture was changed to moles).
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 8
A polyimide varnish having a solid content concentration of 15% by mass was obtained by the same method as in Example 4 except that 21.625 g (0.050 mol) of BAPS was changed to 21.625 g (0.050 mol) of M-BAPS. ..
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 1
Polyimide varnish with a solid content concentration of 20% by mass by the same method as in Example 4 except that BAPS 21.625 g (0.050 mol) was changed to 3,3'-DDS 12.415 g (0.050 mol). Got
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 2
The amount of BAPS was changed from 8.650 g (0.020 mol) to 43.249 g (0.100 mol) and the amount of HPMDA was changed from 11.209 g (0.050 mol) to 22.417 g (0.100 mol). A polyimide varnish having a solid content concentration of 20% by mass was obtained by the same method as in Example 1 except that ODPA and 1,4-BACT were not used.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 3
The amount of M-BAPS was changed from 21.625 g (0.050 mol) to 43.249 g (0.100 mol), and the amount of HPMDA was changed from 11.209 g (0.050 mol) to 22.417 g (0.100 mol). A polyimide varnish having a solid content concentration of 20% by mass was obtained by the same method as in Example 8 except that ODPA and 1,4-BACT were not used.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

The above-mentioned physical properties were measured and evaluated for the polyimide films obtained in Examples and Comparative Examples. The results are shown in Table 1.

As shown in Table 1, it can be seen that the polyimide film of the example has good optical isotropic properties, and is also excellent in toughness and chemical resistance. Comparative Example 1 was excellent in optical isotropic property and chemical resistance, but was inferior in elongation. Comparative Example 2 was inferior in optical isotropic property, chemical resistance, and elongation. In Comparative Example 3, the optical isotropic property was good, but the elongation and chemical resistance were inferior.
Therefore, ODPA and HPMDA are used as the tetracarboxylic acid component, and BAPS or M-BAPS and alicyclic diamines such as 1,3-BAC, 1,4-BAC, and 1,4-BACT are used in combination as the diamine component. The polyimide film can be suitably used as a plastic substrate for a liquid crystal display, an OLED display, a touch panel, or the like as a film having excellent optical isotropic properties, chemical resistance, and elongation.

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 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).
The structural unit B is represented by the structural unit (B1) derived from the compound represented by the following formula (b1), the structural unit (B21) derived from the compound represented by the following formula (b21), and the following formula (b22). A polyimide resin containing at least one structural unit (B2) selected from the group consisting of structural units (B22) derived from the compound.
The polyimide resin according to claim 1, wherein the ratio of the constituent unit (A1) in the constituent unit A is 30 to 90 mol%, and the ratio of the constituent unit (A2) in the constituent unit A is 10 to 70 mol%. ..
The first or second claim, wherein the ratio of the constituent unit (B1) in the constituent unit B is 5 to 80 mol%, and the ratio of the constituent unit (B2) in the constituent unit B is 20 to 95 mol%. Polyimide resin.
A polyimide varnish in which the polyimide resin according to any one of claims 1 to 3 is dissolved in an organic solvent.
A polyimide film containing the polyimide resin according to any one of claims 1 to 3.