WO2021132196A1

WO2021132196A1 - Polyimide resin, polyimide varnish, and polyimide film

Info

Publication number: WO2021132196A1
Application number: PCT/JP2020/047790
Authority: WO
Inventors: 洋平安孫子; 菜摘脇田; 三田寺　淳
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2019-12-27
Filing date: 2020-12-22
Publication date: 2021-07-01
Also published as: CN114867767A; TW202130706A; KR20220123393A; JPWO2021132196A1

Abstract

The present invention provides a polyimide resin, a polyimide varnish, and a polyimide film, the polyimide resin having constituent units A derived from tetracarboxylic dianhydrides and constituent units B derived from diamines, and being such that: the constituent units A include constituent units (A-1) derived from a compound represented by formula (a-1), and constituent units (A-2) derived from a compound represented by formula (a-2); and the constituent units B include constituent units (B-1) derived from a compound represented by formula (b-1), and constituent units (B-2) derived from a compound represented by formula (b-2), the polyimide resin making it possible to form a film that has exceptional optical isotropy and furthermore has exceptional release properties and chemical resistance.

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.
On the other hand, when it is used for applications where light passes through a retardation film or a polarizing plate, for example, a liquid crystal display, a touch panel, etc., it is required to have particularly high optical isotropic properties (that is, low Rth). ..

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

As described above, a polyimide film having excellent optical isotropic properties is required, especially for applications such as displays.
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 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.
When a polyimide film is used as a substrate, the film is brought into close contact with a support such as a glass plate in the process of forming an electronic circuit on the film. Therefore, the property of easily peeling the polyimide film from the support after creating the circuit is also required.
As described above, there has been a demand for a polyimide resin capable of obtaining a polyimide film having excellent peelability and chemical resistance while maintaining the optical characteristics of the obtained polyimide film, particularly optical isotropic property.
Therefore, an object of the present invention is to provide a polyimide resin, a polyimide varnish, and a polyimide film capable of forming a film having excellent optical isotropic properties and also excellent peelability and chemical resistance.

The present inventors have found that a polyimide resin containing a combination of a structural unit derived from two specific types of tetracarboxylic 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 acid dianhydride and a structural unit B derived from diamine, wherein the structural unit A is derived from a compound represented by the following formula (a-1). A compound containing 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). A polyimide resin containing a structural unit (B-1) derived from and a structural unit (B-2) derived from a compound represented by the following formula (b-2).

<2> The ratio of the constituent unit (A-1) in the constituent unit A is 20 to 80 mol%, and the ratio of the constituent unit (A-2) in the constituent unit A is 20 to 80 mol%. The polyimide resin according to <1>.
<3> The ratio of the structural unit (B-1) in the structural unit B is 5 to 80 mol%, and the ratio of the structural unit (B-2) in the structural unit B is 20 to 95 mol%. The polyimide resin according to <1> or <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, it is possible to provide a polyimide resin, a polyimide varnish and a polyimide film capable of forming a film having excellent optical isotropic properties and also excellent peelability and chemical resistance.

[Polyimide resin]
The polyimide resin of the present invention is a polyimide resin having a structural unit A derived from tetracarboxylic acid dianhydride and a structural unit B derived from diamine, and the structural unit A is represented by the following formula (a-1). A structural unit (A-1) derived from a compound and a structural unit (A-2) derived from a compound represented by the following formula (a-2) are included, and the structural unit B is represented by the following formula (b-1). It contains a structural unit (B-1) derived from the compound represented by the compound and a structural unit (B-2) derived from the compound represented by the following formula (b-2).

The reason why the polyimide resin of the present invention is excellent in peelability and chemical resistance while maintaining optical isotropic properties is not clear, but the polyimide resin of the present invention has a sulfonyl structure in addition to an ether structure and is alicyclic. Since it also has a ring structure, it is considered to be excellent in optical isotropic properties, and also in peelability 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 is a structural unit (A-1) derived from a compound represented by the following formula (a-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2). )including.

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

The ratio of the structural unit (A-1) in the structural unit A is preferably 20 to 80 mol%, more preferably 30 to 70 mol%, and further preferably 40 to 60 mol%.
The ratio of the structural unit (A-2) in the structural unit A is preferably 20 to 80 mol%, more preferably 30 to 70 mol%, and further preferably 40 to 60 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. Is. The upper limit 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 only of the structural unit (A-1) and the structural unit (A-2).
In the polyimide resin of the present invention, when the constituent unit A contains both the constituent units (A-1) and (A-2), it becomes optically isotropic, peelable, or chemical resistant as described above. Not only is it excellent, but also the solubility of the polymer produced by the progress of the imidization reaction in the production of the polyimide resin in the solvent is high, and a transparent varnish and film can be obtained.
The molar ratio [(A-1) / (A-2)] of the structural unit (A-1) and the structural unit (A-2) in the structural unit A improves optical isotropic property and chemical resistance. From the viewpoint, it is preferably 20/80 to 80/20, more preferably 30/70 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 (A-1) and the structural unit (A-2). The tetracarboxylic dianhydride giving such a constituent unit is not particularly limited, but is pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 9,9'. Arophilic tetracarboxylic dianhydrides such as -bis (3,4-dicarboxyphenyl) fluorene dianhydride and 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride (provided that the formula (a-1) is used. ); 1,2,3,4-cyclobutanetetracarboxylic dianhydride, norbornane-2-spirio-α-cyclopentanone-α'-spirio-2''-norbornan-5 , 5'', 6,6''-Alicyclic tetracarboxylic dianhydride such as tetracarboxylic dianhydride (excluding the compound represented by the formula (a-2)); and 1,2, , 3,4-Butanetetracarboxylic dianhydride and other aliphatic tetracarboxylic dianhydrides can be mentioned.
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, and is a structural unit (B-1) derived from a compound represented by the following formula (b-1) and the following formula (b-2). Includes a structural unit (B-2) derived from the compound represented by.

The compound represented by the formula (b-1) is 4,4'-diaminodiphenyl sulfone. When the structural unit B includes the structural unit (B-1), the toughness and peelability of the film can be improved, and the heat resistance can also be improved.

The compound represented by the formula (b-2) is bis (aminomethyl) cyclohexane, and specific examples thereof include 1,3-bis (aminomethyl) cyclohexane represented by the following formula (b-2a). Examples thereof include 1,4-bis (aminomethyl) cyclohexane represented by the following formula (b-2b).

The cis: trans ratio of the compound represented by the formula (b-2) is preferably 0: 100 to 80:20, preferably 0.1: 99.9 to 70:30, from the viewpoint of organic solvent resistance and heat resistance. Is more preferable, 0.5: 99.5 to 60:40 is further preferable, and 1:99 to 20:80 is even more preferable.
By including the structural unit (B-2) in the structural unit B, the colorless transparency and optical isotropic property of the film can be improved.

The ratio of the structural unit (B-1) in the structural unit B is preferably 5 to 80 mol%, more preferably 10 to 70 mol%, still more preferably 30 to 70 mol%, and further. It is preferably 45 to 70 mol%, and even more preferably 45 to 60 mol%.
The ratio of the structural unit (B-2) in the structural unit B is preferably 20 to 95 mol%, more preferably 30 to 90 mol%, still more preferably 30 to 70 mol%, and further. It is preferably 30 to 55 mol%, and even more preferably 40 to 55 mol%.
The total ratio of the structural units (B-1) and (B-2) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more. Is. The upper limit of the total ratio of the structural units (B-1) and (B-2) is not particularly limited, that is, 100 mol%. The structural unit B may consist only of the structural unit (B-1) and the structural unit (B-2).
In the polyimide resin of the present invention, when the constituent unit B contains both the constituent units (B-1) and (B-2), it becomes optically isotropic, peelable, or chemical resistant as described above. Not only is it excellent, but also the solubility of the polymer produced by the progress of the imidization reaction in the production of the polyimide resin in the solvent is high, and a transparent varnish and film can be obtained.
The molar ratio [(B-1) / (B-2)] of the structural unit (B-1) and the structural unit (B-2) in the structural unit B improves optical isotropic property and chemical resistance. From the viewpoint, it is preferably 5/95 to 80/20, more preferably 10/90 to 70/30, and further preferably 30/70 to 70/30 from the viewpoint of heat resistance, and from the viewpoint of toughness. Therefore, it is even more preferably 45/55 to 70/30, and even more preferably 45/55 to 60/40.

The structural unit B may include a structural unit other than the structural units (B-1) and (B-2).
In addition to the structural units (B-1) and (B-2), the structural unit B is a structural unit derived from a compound represented by the following formula (b-3) from the viewpoint of heat resistance and colorless transparency (b-3). It is preferable to include B-3).

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

When the constituent unit B includes the constituent unit (B-1), the constituent unit (B-2), and the constituent unit (B-3), the constituent unit (B-1) and the constituent unit (B-2) in the constituent unit B ) Is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, and the ratio of the constituent unit (B-3) in the constituent unit B. Is preferably 1 to 50 mol%, more preferably 5 to 40 mol%, still more preferably 10 to 30 mol%.
The total ratio of the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3) in the structural unit B is preferably 80 mol% or more, more preferably 90 mol% or more. It is particularly preferably 99 mol% or more. The upper limit of the ratio of the total of the structural unit (B-1), the structural unit (B-2) and the structural unit (B-3) is not particularly limited, that is, 100 mol%. The structural unit B may be composed of only the structural unit (B-1), the structural unit (B-2), and the structural unit (B-3).

The structural unit B may include a structural unit other than the structural units (B-1), (B-2) and (B-3). The diamine that gives such a structural unit is not particularly limited, but is limited to 1,4-phenylenediamine, p-xylylene diamine, 1,5-diaminonaphthalene, and 2,2'-dimethylbiphenyl-4,4'-diamine. , 4,4'-Diaminodiphenyl 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-aminophenoxy) phenyl] propane, 2,2-bis (4- (4- (4- (4- (4-)4-) Aromatic diamines such as aminophenoxy) phenyl) hexafluoropropane and 9,9-bis (4-aminophenyl) fluorene (however, compounds represented by formula (b-1) and represented by formula (b-3). (Excluding compounds to be used); alicyclic diamines (excluding compounds represented by the formula (b-2)); and aliphatic diamines such as ethylenediamine and hexamethylenediamine.
In the present specification, the aromatic diamine means a diamine containing one or more aromatic rings, and the alicyclic diamine means a diamine containing one or more alicyclic rings and 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 other than the structural unit (B-1) and the structural unit (B-2) arbitrarily included in the structural unit B may be one type or two or more types.

<Characteristics of polyimide resin>
The number 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 number average molecular weight of the polyimide resin can be obtained 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, it may be 100% by mass.

The polyimide resin composition of the present invention containing the above-mentioned polyimide resin can form a film excellent in optical isotropic property, peelability 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 4.5 or less, more preferably 3.0 or less, still more preferably 2.0 or less, and even more preferably 2.0 or less when the film has a thickness of 10 μm. It is 1.5 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 40 nm or less, and even more preferably 30 nm when the film has a thickness of 10 μm.

In addition, the film that can be formed using the 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, and further preferably 2.5 GPa or more.
The tensile elongation at break is preferably 5% or more, more preferably 6% or more, and further preferably 7% 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>
In the present invention, the polyimide resin contains a tetracarboxylic acid component containing a compound giving the above-mentioned structural unit (A-1) and a compound giving the above-mentioned structural unit (A-2), and the above-mentioned structural unit (B-1). It can be produced by reacting with a diamine component containing a compound giving the above-mentioned structural unit (B-2).

Examples of the compound giving the structural unit (A-1) include the compound represented by the formula (a-1), 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 (a-1), and an alkyl ester of the tetracarboxylic acid. .. Of these, the tetracarboxylic dianhydride represented by the formula (a-1) is preferable.
Similarly, the compound giving the structural unit (A-2) includes a compound represented by the formula (a-2), 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 (a-2) (that is, 1,2,4,5-cyclohexanetetracarboxylic acid), and the tetracarboxylic acid. Alkyl esters can be mentioned. Of these, the tetracarboxylic dianhydride represented by the formula (a-2) is preferable.

The tetracarboxylic acid component preferably contains 20 to 80 mol%, more preferably 30 to 70 mol%, and further preferably 40 to 60 mol% of the compound giving the structural unit (A-1).
The tetracarboxylic acid component preferably contains 20 to 80 mol%, more preferably 30 to 70 mol%, and further preferably 40 to 60 mol% of the compound giving the structural unit (A-2).
The tetracarboxylic acid component contains, in total, a compound giving the structural unit (A-1) and a compound giving the structural unit (A-2) in an amount of preferably 50 mol% or more, more preferably 70 mol% or more, and more preferably. Contains 90 mol% or more. The upper limit of the total content of the compound giving the structural unit (A-1) and the compound giving the structural unit (A-2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist only of a compound giving a structural unit (A-1) and a compound giving a structural unit (A-2).
The molar ratio [(A-1) / (A-2)] of the compound giving the constituent unit (A-1) to the compound giving the constituent unit (A-2) in the tetracarboxylic acid component is preferably 20/80. It is -80/20, more preferably 30/70 to 70/30, and even more preferably 40/60 to 60/40.

The tetracarboxylic acid component may contain a compound other than the compound giving the structural unit (A-1) and the compound giving the structural unit (A-2).
Such arbitrary compounds include the above-mentioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic dian, tetra). Alkyl ester of carboxylic acid, etc.).
The compound that gives the constituent unit (A-1) arbitrarily contained in the tetracarboxylic acid component and the compound other than the compound that gives the constituent unit (A-2) may be one kind or two or more kinds.

Examples of the compound giving the structural unit (B-1) include the compound represented by the formula (b-1), 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 diisocyanate corresponding to the compound represented by the formula (b-1). As the compound that gives the structural unit (B-1), the compound represented by the formula (b-1) (that is, a diamine) is preferable.
Similarly, the compound giving the structural unit (B-2) includes a compound represented by the formula (b-2), 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 diisocyanate corresponding to the compound represented by the formula (b-2). As the compound giving the structural unit (B-2), the compound represented by the formula (b-2) (that is, diamine) is preferable.

The diamine component preferably contains a compound that gives the structural unit (B-1) in an amount of 5 to 80 mol%, more preferably 10 to 70 mol%, still more preferably 30 to 70 mol%, and even more preferably 45. It contains ~ 70 mol%, more preferably 45-60 mol%.
The diamine component preferably contains a compound that gives the structural unit (B-2) in an amount of 20 to 95 mol%, more preferably 30 to 90 mol%, still more preferably 30 to 70 mol%, and even more preferably 30. It contains ~ 55 mol%, more preferably 40-55 mol%.
The diamine component contains, in total, a compound giving the structural unit (B-1) and a compound giving the structural unit (B-2) in an amount of 50 mol% or more, more preferably 70 mol% or more, and more preferably 90. Contains more than mol%. The upper limit of the total content of the compound giving the structural unit (B-1) and the compound giving the structural unit (B-2) is not particularly limited, that is, 100 mol%. The diamine component may consist only of a compound giving a structural unit (B-1) and a compound giving a structural unit (B-2).
The molar ratio [(B-1) / (B-2)] of the compound giving the structural unit (B-1) to the compound giving the structural unit (B-2) in the diamine component is optically isotropic and resistant to light. From the viewpoint of improving chemical properties, it is preferably 5/95 to 80/20, more preferably 10/90 to 70/30, and further preferably 30/70 to 70/30 from the viewpoint of heat resistance. From the viewpoint of toughness, it is even more preferably 45/55 to 70/30, and even more preferably 45/55 to 60/40.

The diamine component may contain a compound other than the compound giving the structural unit (B-1) and the compound giving the structural unit (B-2).

The diamine component may further contain a compound giving the structural unit (B-3) in addition to the compound giving the structural unit (B-1) and the compound giving the structural unit (B-2).
Examples of the compound giving the structural unit (B-3) include the compound represented by the formula (b-3), 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 diisocyanate corresponding to the compound represented by the formula (b-3). As the compound giving the structural unit (B-3), the compound represented by the formula (b-3) (that is, diamine) is preferable.

The diamine component preferably contains a compound that gives the structural unit (B-3) in an amount of 1 to 50 mol%, more preferably 5 to 40 mol%, and even more preferably 10 to 30 mol%.
When the diamine component contains a compound that gives a constituent unit (B-3), the diamine component includes a compound that gives a constituent unit (B-1), a compound that gives a constituent unit (B-2), and a constituent unit (B-3). In total, it contains 80 mol% or more, more preferably 90 mol% or more, and further preferably 99 mol% or more. The upper limit of the total content of the compound giving the structural unit (B-1), the compound giving the structural unit (B-2), and the compound giving the structural unit (B-3) is not particularly limited, that is, 100 mol. %. The diamine component may consist only of a compound giving a structural unit (B-1), a compound giving a structural unit (B-2), and a compound giving a structural unit (B-3).

The compound other than the compound giving the structural unit (B-1) arbitrarily contained in the diamine component and the compound giving the structural unit (B-2) is not limited to the compound giving the structural unit (B-3). Such arbitrary compounds include the above-mentioned aromatic diamines, alicyclic diamines, and aliphatic diamines, and derivatives thereof (diisocyanate and the like).
The compound that gives the constituent unit (B-1) arbitrarily contained in the diamine component and the compound other than the compound that gives the constituent unit (B-2) may be one kind or two or more kinds.

In the present invention, the ratio of the amount of the tetracarboxylic acid component to the diamine component charged in the production of the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component with respect to 1 mol of the tetracarboxylic acid component.

Further, in the present invention, in addition to the above-mentioned tetracarboxylic acid component and diamine component, an end-capping agent may be used for producing the polyimide resin. 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 0 to 80 ° 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 was charged, and if necessary, the mixture was stirred at room temperature of 0 to 80 ° C. for 0.5 to 30 hours. After that, a method of raising the temperature to carry out the imidization reaction, (3) a method of charging the tetracarboxylic acid component, the diamine component, and the reaction solvent into the reactor and immediately raising the temperature to carry out the imidization reaction can be mentioned.

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, and amide solvents and lactone solvents are 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.

In the polyimide resin of the present invention, the constituent unit A contains the constituent units (A-1) and (A-2), and the constituent unit B contains the constituent units (B-1) and (B-2). A transparent varnish can be obtained with high solubility of the polymer produced by the progress of the chemical reaction in the solvent.

[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 10 to 30% 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.
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. Above all, the slit coat is 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 pressure.
The method of peeling the polyimide film formed on the support from the support is not particularly limited, but 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 includes a compound giving the above-mentioned structural unit (A-1) and a compound giving the above-mentioned structural unit (A-2). It is a product of a polyaddition reaction of a tetracarboxylic acid component and a diamine component containing the above-mentioned compound giving the structural unit (B-1) and the compound giving the structural unit (B-2). 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 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 a solvent for the polyamic acid solution. May be added and diluted.

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 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 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 application and the like, 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 viscosity of the polyimide varnish.

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 elastic modulus, and tensile elongation at break The tensile strength, tensile elastic modulus, and elongation at break are in accordance with JIS K7127: 1999, and the tensile tester "Strograph VG-" manufactured by Toyo Seiki Co., Ltd. 1E ”was used for measurement. 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 Kogyo 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 Kogyo 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

(7) Releasability The polyimide film formed on the glass plate was cut into 8 cm squares with a cutter knife, and the film was peeled off from the glass plate with tweezers to evaluate the releasability.
Those that can be peeled off without immersing the film and glass plate in water have good peelability, and those that cannot be peeled off without immersing the film and glass plate in water have poor peelability.
In Table 1, when the peelability was good, it was given as “A”, and when the peelability was poor, it was given as “C”.
In the evaluations (1) to (6) above, when the film immersed in water was used, the film was dried at 90 ° C. for 1 hour before the measurement and evaluation.

(8) Solvent resistance A polyimide film formed on a glass plate was immersed in a solvent at room temperature, and it was confirmed whether or not there was any change in the film surface. 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 slightly cracked.
C: 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 (a-1))
HPMDA: 1,2,4,5-Cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (a-2))
6FDA: 4,4'-(hexafluoroisopropylidene) diphthalic anhydride

(Diamine component)
4,4'-DDS: 4,4'-diaminodiphenyl sulfone (manufactured by Seika Co., Ltd .; compound represented by formula (b-1))
1,3-BAC: 1,3-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (b-2a))
1,4-BACT: 1,4-bis (aminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc .; compound represented by formula (b-2b); trans ratio 85%)
6FODA: 4,4'-diamino-2,2'-bistrifluoromethyldiphenyl ether (manufactured by ChinaTech Chemical (Tianjin) Co., Ltd; compound represented by formula (b-3))
3,3'-DDS: 3,3'-diaminodiphenyl sulfone (manufactured by Seika Co., Ltd.)

<Manufacturing of polyimide resin, varnish and polyimide film>
Example 1
12.415 g of 4,4'-DDS in a 300 mL five-necked round-bottom flask equipped with a stainless half-moon agitator, a nitrogen inlet tube, a Dean Stark with a cooling tube, a thermometer, and a glass end cap. 0.050 mol), 7.113 g (0.050 mol) of 1,4-BACT and 55.496 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added, and the mixture was rotated at a system temperature of 70 ° C. and a nitrogen atmosphere. A solution was obtained by stirring at several 200 rpm.
To this solution, 15.511 g (0.050 mol) of ODPA, 11.209 g (0.050 mol) of HPMDA, and 13.874 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 the mixture was 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 about 5 hours while adjusting the rotation speed according to the increase in viscosity.
Then, 101.200 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added so that the solid content concentration was 20% 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 7.113 g (0.050 mol) to 11.380 g (0.080 mol), and the amount of 4,4'-DDS was changed from 12.415 g (0.050 mol). A polyimide varnish having a solid content concentration of 20% by mass was obtained in the same manner as in Example 1 except that the content was changed to 4.966 g (0.020 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 7.113 g (0.050 mol) to 8.535 g (0.060 mol), and the amount of 4,4'-DDS was changed from 12.415 g (0.050 mol). A polyimide varnish having a solid content concentration of 20% by mass was obtained in the same manner as in Example 1 except that the content was changed to 9.923 g (0.040 mol).
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 4
Examples except that the amount of 4,4'-DDS was changed from 12.415 g (0.050 mol) to 4.966 g (0.020 mol) and 10.087 g (0.030 mol) of 6FODA was added. In the same manner as in No. 1, a polyimide varnish having a solid content concentration of 20% by mass was obtained.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Example 5
In the same manner as in Example 1, the solid content concentration was 20% by mass, except that 1,4-BACT 7.13 g (0.050 mol) was changed to 1,3-BAC 7.113 g (0.050 mol). A polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 1
Solid content concentration in the same manner as in Example 1 except that ODPA 15.511 g (0.050 mol) and HPMDA 11.209 g (0.050 mol) were changed to 6FDA 44.424 (0.100 mol). A 20% by mass polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 2
A polyimide varnish having a solid content concentration of 20% by mass was obtained in the same manner as in Example 1 except that 11.209 g (0.050 mol) of HPMDA was changed to 22.212 g (0.050 mol) of 6FDA.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 3
Solid content concentration 20 in the same manner as in Example 1 except that 4,4'-DDS 12.415 g (0.050 mol) was changed to 3,3'-DDS 12.415 g (0.050 mol). A weight% polyimide varnish was obtained.
Using the obtained polyimide varnish, a film was obtained by the same method as in Example 1.

Comparative Example 4
The imidization reaction was carried out in the same manner as in Example 1 except that HPMDA was not used and the amount of ODPA was changed from 15.511 g (0.050 mol) to 31.021 g (0.100 mol). However, after adding triethylamine, the reaction solution became cloudy in the process of raising the temperature in the reaction system to 190 ° C., and no varnish was obtained.

Comparative Example 5
The amount of 4,4'-DDS was changed from 12.415 g (0.050 mol) to 24.830 g (0.100 mol) without using 1,4-BACT and without HPMDA of ODPA. The imidization reaction was carried out in the same manner as in Example 1 except that the amount was changed from 15.511 g (0.050 mol) to 31.021 g (0.100 mol). However, after adding triethylamine, the reaction solution became cloudy in the process of raising the temperature in the reaction system to 190 ° C., and no varnish was obtained.

Comparative Example 6
Change the amount of 4,4'-DDS from 12.415 g (0.050 mol) to 24.830 g (0.100 mol) without using 1,4-BACT, without using ODPA, HPMDA The imidization reaction was carried out in the same manner as in Example 1 except that the amount was changed from 11.209 g (0.050 mol) to 22.417 g (0.100 mol). However, after adding triethylamine, the reaction solution became cloudy in the process of raising the temperature in the reaction system to 190 ° C., and no varnish was obtained.

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 peelability and chemical resistance.

The polyimide film containing the polyimide resin of the present invention has good optical isotropic properties, and also has excellent peelability and chemical resistance, and is a film for various members such as color filters, flexible displays, semiconductor parts, and optical members. It is preferably used as. The polyimide film containing the polyimide resin 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.

Claims

A polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine.
A structural unit (A-1) in which the structural unit A is derived from a compound represented by the following formula (a-1) and a structural unit (A-2) derived from a compound represented by the following formula (a-2). Including
A structural unit (B-1) in which the structural unit B is derived from a compound represented by the following formula (b-1) and a structural unit (B-2) derived from a compound represented by the following formula (b-2). Polyimide resin containing.
According to claim 1, the ratio of the constituent unit (A-1) in the constituent unit A is 20 to 80 mol%, and the ratio of the constituent unit (A-2) in the constituent unit A is 20 to 80 mol%. The polyimide resin described.
Claim 1 or claim 1, wherein the ratio of the constituent unit (B-1) in the constituent unit B is 5 to 80 mol%, and the ratio of the constituent unit (B-2) in the constituent unit B is 20 to 95 mol%. 2. The polyimide resin according to 2.
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.