KR20200124670A - Polyimide resin, polyimide varnish and polyimide film - Google Patents

Abstract

(식(b-1) 중, R₁~R₄는, 각각 독립적으로, 1가의 지방족기 또는 1가의 방향족기이고, Z₁ 및 Z₂는, 각각 독립적으로, 2가의 지방족기 또는 2가의 방향족기이고, r은, 양의 정수이다.)The present invention provides a polyimide resin capable of forming a film having excellent colorless transparency and optical isotropy and having a low elastic modulus, wherein the structural unit A derived from tetracarboxylic dianhydride is represented by formula (a-1). Constituent unit (B-1) derived from a compound represented by formula (b-1), and formula (b-2) in which the constituent unit B derived from diamine is included in the constituent unit (A-1) derived from the compound. The structural unit derived from the compound represented by -1) (B-2-1), the structural unit derived from the compound represented by formula (b-2-2) (B-2-2), and the formula (b- A polyimide resin containing at least one structural unit (B-2) selected from the group consisting of a structural unit (B-2-3) derived from a compound represented by 2-3), and this polyimide resin It relates to a polyimide varnish and a polyimide film containing.

(In formula (b-1), R ₁ to R ₄ are each independently a monovalent aliphatic group or a monovalent aromatic group, and Z ₁ and Z ₂ are each independently a divalent aliphatic group or a divalent aromatic Group, and r is a positive integer.)

Description

Polyimide resin, polyimide varnish and polyimide film

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

Since polyimide resin has excellent mechanical properties and heat resistance, various uses in fields such as electric and electronic parts are being studied. 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, and research on a polyimide film suitable as a corresponding plastic substrate is also underway. The polyimide film for this purpose is required to have excellent colorless transparency.

In addition, in order to be suitable as a plastic substrate used in an image display device (for example, a liquid crystal display) in which light emitted from a display device passes through a retardation film or a polarizing plate, polyimide film has not only excellent colorless transparency, but also excellent optical isotropy. Is also required.

In order to satisfy the required performance as described above, various polyimide resins are being developed. For example, in Patent Document 1, as a polyimide resin having good transparency, heat resistance and optical isotropy, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride is used as a tetracarboxylic acid component, and 9 as a diamine component. , 9-bis(3-methyl-4-aminophenyl)fluorene and a polyimide resin synthesized using 4,4'-diaminodiphenyl ether, and the like are disclosed.

Japanese Patent No. 6010533

One of the purposes of replacing a glass substrate used in an image display device with a plastic substrate is to make the device flexible. Polyimide resin, compared to glass, can be said to be a material having high flexibility (ie, low elastic modulus). However, in general, polyimide resins tend to have a high elastic modulus compared to other plastic materials, since the main chain is rigid. Therefore, in order to use a polyimide film as a flexible substrate, lowering the modulus of elasticity is one problem, and it was not easy to achieve it while maintaining excellent colorless transparency and optical isotropy.

The present invention has been made in view of the above situation, and an object of the present invention is to provide a polyimide resin capable of forming a film having excellent colorless transparency and optical isotropy, and having a low elastic modulus.

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

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

[One]

As a polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,

Constituent unit A includes a structural unit (A-1) derived from a compound represented by the following formula (a-1),

Structural unit B is a structural unit (B-1) derived from a compound represented by the following formula (b-1), and a structural unit (B-2-1) derived from a compound represented by the following formula (b-2-1). 1), a structural unit derived from a compound represented by the following formula (b-2-2) (B-2-2), and a structural unit derived from a compound represented by the following formula (b-2-3) (B A polyimide resin containing at least one structural unit (B-2) selected from the group consisting of -2-3).

[Formula 1]

(In formula (b-1),

R ₁ to R ₄ are each independently a monovalent aliphatic group or a monovalent aromatic group,

Z ₁ and Z ₂ are each independently a divalent aliphatic group or a divalent aromatic group,

r is a positive integer.)

[2]

The polyimide resin according to the above [1], wherein the proportion of the structural unit (A-1) in the structural unit A is 50 mol% or more.

[3]

The proportion of the structural unit (B-1) in the structural unit B is 10 to 50 mol%,

The polyimide resin according to [1] or [2], wherein the proportion of the structural unit (B-2) in the structural unit B is 50 to 90 mol%.

[4]

The polyimide resin according to any one of the above [1] to [3], wherein the structural unit (B-2) is a structural unit (B-2-1).

[5]

The polyimide resin according to any one of the above [1] to [3], wherein the structural unit (B-2) is a structural unit (B-2-2).

[6]

The polyimide resin according to any one of the above [1] to [3], wherein the structural unit (B-2) is a structural unit (B-2-3).

[7]

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

[8]

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

According to the present invention, a film having excellent colorless transparency and optical isotropy and having a low elastic modulus can be formed.

[Polyimide resin]

The polyimide resin of the present invention has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine, and the structural unit A is a structural unit derived from a compound represented by the following formula (a-1) In the structural unit (B-1) derived from the compound represented by the following formula (b-1), and the compound represented by the following formula (b-2-1), in which the structural unit B is The derived structural unit (B-2-1), the structural unit derived from the compound represented by the following formula (b-2-2) (B-2-2), and represented by the following formula (b-2-3) And at least one constitutional unit (B-2) selected from the group consisting of constitutional units (B-2-3) derived from the compound.

[Formula 2]

(In formula (b-1),

R ₁ to R ₄ are each independently a monovalent aliphatic group or a monovalent aromatic group,

Z ₁ and Z ₂ are each independently a divalent aliphatic group or a divalent aromatic group,

r is a positive integer.)

<Constituent Unit A>

Structural unit A is a structural unit derived from tetracarboxylic dianhydride occupied in the polyimide resin, and includes a structural unit (A-1) derived from a compound represented by the following formula (a-1).

[Formula 3]

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

When the structural unit A contains the structural unit (A-1), it contributes to the improvement of the colorless transparency of the film.

The proportion of the structural unit (A-1) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, and particularly preferably It is more than 99 mol%. The upper limit of the proportion of the structural unit (A-1) is not particularly limited, that is, 100 mol%. Constituent unit A may consist of only constituent units (A-1).

The structural unit A may include structural units other than the structural unit (A-1). The tetracarboxylic acid dianhydride giving such a structural unit is not particularly limited, but pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 9,9'-bis( Aromatic tetracarboxylic acid dianhydrides such as 3,4-dicarboxyphenyl)fluorene dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride; 1,2,3,4-cyclobutanetetracarboxylic dianhydride and nobonan-2-spiro-α-cyclopentanone-α'-spiro-2”-novonane-5,5”,6,6”- Alicyclic tetracarboxylic dianhydrides such as tetracarboxylic dianhydride (however, the compound represented by formula (a-1) is excluded); And aliphatic tetracarboxylic dianhydrides, such as 1,2,3,4-butane tetracarboxylic dianhydride, are mentioned.

Meanwhile, in the present specification, the aromatic tetracarboxylic dianhydride refers to a tetracarboxylic acid dianhydride containing at least one aromatic ring, and the alicyclic tetracarboxylic dianhydride includes at least one alicyclic ring, and It means a tetracarboxylic acid dianhydride which does not contain, and the aliphatic tetracarboxylic acid dianhydride means a tetracarboxylic acid dianhydride which does not contain neither an aromatic ring nor an alicyclic ring.

Constituent units other than the constituent unit (A-1) arbitrarily included in the constituent unit A may be one type or two or more types.

Further, as an aspect of the polyimide resin of the present invention, a polyimide resin in which the structural unit A does not contain a structural unit derived from 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride is mentioned. I can.

<Constituent Unit B>

Structural unit B is a structural unit derived from a diamine occupied in the polyimide resin, and a structural unit (B-1) derived from a compound represented by the following formula (b-1), and the following formula (b-2-1) A structural unit derived from a compound represented by (B-2-1), a structural unit derived from a compound represented by the following formula (b-2-2) (B-2-2), and the following formula (b-2) It includes at least one structural unit (B-2) selected from the group consisting of structural units (B-2-3) derived from the compound represented by -3).

[Formula 4]

(In formula (b-1),

R ₁ to R ₄ are each independently a monovalent aliphatic group or a monovalent aromatic group,

Z ₁ and Z ₂ are each independently a divalent aliphatic group or a divalent aromatic group,

r is a positive integer.)

R ₁ , R ₂ , R ₃ and R ₄ in the formula (b-1) each independently represent a monovalent aliphatic group or a monovalent aromatic group, and at least some of these groups may be substituted with a fluorine atom. . Examples of the monovalent aliphatic group include a monovalent saturated hydrocarbon group, a monovalent unsaturated hydrocarbon group, and a monovalent hydrocarbonoxy group. Examples of the monovalent saturated hydrocarbon group include an alkyl group having 1 to 22 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. Examples of the monovalent unsaturated hydrocarbon group include an alkenyl group having 2 to 22 carbon atoms, and examples thereof include a vinyl group and a propenyl group. Examples of the monovalent hydrocarbonoxy group include an alkoxy group having 1 to 22 carbon atoms, and for example, a monovalent group formed by bonding an oxygen atom to the alkyl group exemplified above can be exemplified. Examples of the monovalent aromatic group include an aryl group having 6 to 24 carbon atoms, an aralkyl group having 7 to 24 carbon atoms, and an aryloxy group having 6 to 24 carbon atoms, and examples thereof include a phenyl group and a phenoxy group. . As R ₁ , R ₂ , R ₃ and R ₄ , a methyl group or a phenyl group is particularly preferable.

Further, Z ₁ and Z ₂ each independently represent a divalent aliphatic group or a divalent aromatic group, and at least some of these groups may be substituted with a fluorine atom. Examples of the divalent aliphatic group include a divalent saturated hydrocarbon group or a divalent unsaturated hydrocarbon group. Examples of the divalent saturated hydrocarbon group include an alkylene group having 1 to 22 carbon atoms. For example, a methylene group, ethylene group, propylene group, trimethylene group, tetramethylene group, hexamethylene group, octamethylene group, decamethylene group , Dodecamethylene group, etc. can be illustrated. Examples of the divalent unsaturated hydrocarbon group include an unsaturated carbon group having 2 to 22 carbon atoms, and examples thereof include a vinylene group, a propenylene group, and an alkylene group having an unsaturated double bond at the terminal. Examples of the divalent aromatic group include an arylene group having 6 to 24 carbon atoms, an aralkylene group having 7 to 24 carbon atoms, and an aryleneoxy group having 6 to 24 carbon atoms. At least part of the hydrogen atoms constituting the aromatic ring may be substituted with an alkyl group in these groups. Specific examples of the arylene group having 6 to 24 carbon atoms in Z ₁ and Z ₂ include o-phenylene group, m-phenylene group, p-phenylene group, 4,4'-biphenylylene group, 2,6- Naphthylene group, etc. are mentioned. As a specific example of a C7-C24 aralkylene group, a benzylene group, a phenethylene group, etc. are mentioned. Specific examples of the aryleneoxy group having 6 to 24 carbon atoms include a divalent group formed by bonding an oxygen atom to the arylene group exemplified above. As Z ₁ and Z ₂ , a propylene group, a trimethylene group, a tetramethylene group, a p-phenylene group, and a benzylen group are preferable, and a trimethylene group, a tetramethylene group, and a p-phenylene group are more preferable.

In addition, r represents a positive integer, and it is preferable that it is an integer of 2-50. When r is 2 or more, a plurality of R ₁ and R ₂ may each be the same or different from each other.

As the compound represented by formula (b-1), 1,3-bis(3-aminopropyl)-1,1,2,2-tetramethyldisiloxane, 1,3-bis(3-aminobutyl)- 1,1,2,2-tetramethyldisiloxane, 1,3-bis(4-aminophenoxy)tetramethyldisiloxane, 1,1,3,3-tetramethyl-1,3-bis(4-amino Phenyl)disiloxane, 1,1,3,3-tetraphenoxy-1,3-bis(2-aminoethyl)disiloxane, 1,1,3,3-tetraphenyl-1,3-bis(2- Aminoethyl)disiloxane, 1,1,3,3-tetraphenyl-1,3-bis(3-aminopropyl)disiloxane, 1,1,3,3-tetramethyl-1,3-bis(2- Aminoethyl)disiloxane, 1,1,3,3-tetramethyl-1,3-bis(3-aminopropyl)disiloxane, 1,1,3,3-tetramethyl-1,3-bis(4- Aminobutyl)disiloxane, 1,3-dimethyl-1,3-dimethoxy-1,3-bis(4-aminobutyl)disiloxane, 1,1,3,3,5,5-hexamethyl-1, 5-bis(4-aminophenyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,5,5 -Tetraphenyl-3,3-dimethoxy-1,5-bis(4-aminobutyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis(5 -Aminopentyl) trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(2-aminoethyl) trisiloxane, 1,1,5,5-tetramethyl- 3,3-dimethoxy-1,5-bis(4-aminobutyl)trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(5-aminopentyl) Trisiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,3,3,5,5-hexaethyl-1,5 -Bis(3-aminopropyl)trisiloxane, 1,1,3,3,5,5-hexapropyl-1,5-bis(3-aminopropyl) trisiloxane, etc. are mentioned. The compound represented by formula (b-1) may be used alone, or two or more types may be used in combination.

As commercial products of the compound represented by formula (b-1), "X-22-9409", "X-22-1660B", "X-22-161AS" manufactured by Shin-Etsu Chemical Industries, Ltd. , "X-22-161A", "X-22-161B", etc. are mentioned.

When the structural unit B contains the structural unit (B-1), it contributes to the improvement of the optical isotropy and reduction of the elastic modulus of the film.

The compound represented by formula (b-2-1) is 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

The compound represented by formula (b-2-2) is 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

The compound represented by formula (b-2-3) is 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine.

In the present invention, when the structural unit B includes the structural unit (B-2) in combination with the structural unit (B-1), the glass transition temperature of the film can be controlled. The structural unit (B-1) contributes to improving the optical isotropy and lowering the elastic modulus of the film, but also has an aspect of lowering the glass transition temperature. Accordingly, when the structural unit B includes the structural unit (B-2), the decrease in the glass transition temperature due to the structural unit (B-1) can be reduced, and the glass transition temperature of the film can be controlled. Further, from the viewpoint of obtaining a film having excellent colorless transparency and excellent optical isotropy, it is preferable that the structural unit (B-2) is included in the structural unit B.

The structural unit (B-2) may be only the structural unit (B-2-1), only the structural unit (B-2-2), or only the structural unit (B-2-3).

In addition, the structural unit (B-2) may be a combination of the structural unit (B-2-1) and the structural unit (B-2-2), or the structural unit (B-2-2) and the structural unit (B It may be a combination of -2-3), or may be a combination of a structural unit (B-2-1) and a structural unit (B-2-3).

Further, the structural unit (B-2) may be a combination of the structural unit (B-2-1), the structural unit (B-2-2), and the structural unit (B-2-3).

The proportion of the structural unit (B-1) in the structural unit B is preferably 10 to 50 mol%, more preferably 10 to 40 mol%, further preferably 15 to 30 mol%, particularly Preferably it is 15 to 25 mol%.

The proportion of the structural unit (B-2) in the structural unit B is preferably 50 to 90 mol%, more preferably 60 to 90 mol%, still more preferably 70 to 85 mol%, particularly Preferably it is 75 to 85 mol%.

The proportion of the total of the structural unit (B-1) and the structural unit (B-2) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably It is 90 mol% or more, particularly preferably 99 mol% or more. The upper limit of the ratio of the total of the structural unit (B-1) and the structural unit (B-2) is not particularly limited, that is, 100 mol%. Constituent unit B may consist of only the constituent unit (B-1) and the constituent unit (B-2).

The structural unit B may include structural units other than the structural units (B-1) and (B-2). The diamine giving such a structural unit is not particularly limited, but 1,4-phenylenediamine, p-xylylenediamine, 3,5-diaminobenzoic acid, 2,2'-dimethylbiphenyl-4,4' -Diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl) Hexafluoropropane, bis(4-aminophenyl)sulfone, 4,4'-diaminobenzanilide, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N' Aromatic diamines such as -bis(4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl, and 9,9-bis(4-aminophenyl)fluorene (however, formula ( The compound represented by b-1), the compound represented by the formula (b-2-1), the compound represented by the formula (b-2-2), and the compound represented by the formula (b-2-3) are excluded. ); Alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; And aliphatic diamines, such as ethylenediamine and hexamethylenediamine (however, the compound represented by formula (b-1) is excluded) can be mentioned.

Meanwhile, in the present specification, the aromatic diamine means a diamine containing at least one aromatic ring, the alicyclic diamine means a diamine containing at least one alicyclic ring, and does not contain an aromatic ring, and the aliphatic diamine means It means a diamine which does not contain neither an aromatic ring nor an alicyclic ring.

The structural units other than the structural units (B-1) and (B-2) optionally included in the structural unit B may be one type, or may be two or more types.

The number average molecular weight of the polyimide resin of the present invention is preferably 5,000 to 100,000 from the viewpoint of the mechanical strength of the obtained polyimide film. On the other hand, the number average molecular weight of the polyimide resin can be obtained from, for example, a standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration chromatography.

By using the polyimide resin of the present invention, a film having excellent colorless transparency and optical isotropy and low elastic modulus can be formed. Suitable physical property values of the film obtained by using the polyimide resin of the present invention are as follows.

The tensile modulus of elasticity is preferably 2.1 GPa or less, more preferably 2.0 GPa or less, and still more preferably 1.8 GPa or less.

The tensile strength is preferably 40 MPa or more, more preferably 50 MPa or more, and still more preferably 60 MPa or more.

The total light transmittance is preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more when a film having a thickness of 30 μm is used.

Haze is preferably 1.0% or less, more preferably 0.5% or less, and still more preferably 0.3% or less when a film having a thickness of 30 μm is used.

When the yellow index (YI) is a film having a thickness of 30 μm, it is preferably 6.0 or less, more preferably 3.0 or less, and still more preferably 1.5 or less.

The absolute value of the thickness phase difference Rth is preferably 100 nm or less, more preferably 50 nm or less, and still more preferably 30 nm or less when a film having a thickness of 30 μm is used.

The glass transition temperature (Tg) is preferably 150 to 300°C, more preferably 150 to 280°C, and still more preferably 150 to 250°C.

On the other hand, the tensile modulus, tensile strength, total light transmittance, haze, yellow index (YI), thickness phase difference (Rth) and glass transition temperature (Tg) in the present invention can be specifically measured by the method described in the examples. have.

[Method for producing polyimide resin]

The polyimide resin of the present invention includes a tetracarboxylic acid component containing a compound that provides the structural unit (A-1) described above, a compound that provides the structural unit (B-1) described above, and the configuration described above. It can be manufactured by reacting the diamine component containing the compound which gives the unit (B-2).

Examples of the compound to which the structural unit (A-1) is provided include, but are not limited to, the compound represented by the formula (a-1), and may be a derivative thereof within the range to which the same structural unit is provided. Examples of the derivatives include tetracarboxylic acids (i.e. 1,2,4,5-cyclohexanetetracarboxylic acids) corresponding to tetracarboxylic dianhydrides represented by formula (a-1), and alkyls of the tetracarboxylic acids. Esters are mentioned. As the compound giving the structural unit (A-1), a compound represented by formula (a-1) (that is, a dianhydride) is preferable.

The tetracarboxylic acid component contains preferably 50 mol% or more, more preferably 70 mol% or more, and still more preferably 90 mol% or more of the compound that imparts the structural unit (A-1), , Particularly preferably 99 mol% or more. The upper limit of the content of the compound giving the structural unit (A-1) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may consist of only a compound which gives a structural unit (A-1).

The tetracarboxylic acid component may contain compounds other than the compound which imparts the structural unit (A-1), and as the compound, the aromatic tetracarboxylic acid dianhydride described above, the alicyclic tetracarboxylic acid dianhydride, and Aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic acid, alkyl ester of tetracarboxylic acid, etc.) are mentioned.

The number of compounds other than the compound which imparts the structural unit (A-1) optionally contained in the tetracarboxylic acid component may be one, or may be two or more.

Examples of the compound to impart the structural unit (B-1) include, but are not limited to, the compound represented by the formula (b-1), and may be a derivative thereof within the range to which the same structural unit is imparted. Examples of the derivatives include diisocyanates corresponding to diamines represented by formula (b-1). As the compound giving the structural unit (B-1), a compound represented by formula (b-1) (ie, diamine) is preferable.

As the compound to which the structural unit (B-2) is provided, the compound to which the structural unit (B-2-1) is provided, the compound to which the structural unit (B-2-2) is provided, and the structural unit (B-2-1) At least one selected from the group consisting of compounds to impart 3) is used.

As the compound giving the structural unit (B-2-1), the compound giving the structural unit (B-2-2), and the compound giving the structural unit (B-2-3), the formula (b The compound represented by -2-1), the compound represented by the formula (b-2-2), and the compound represented by the formula (b-2-3) are exemplified, but are not limited thereto, and the same structural unit It may be a derivative thereof within the range of giving. As the derivative, diisocyanate corresponding to diamine represented by the compound represented by formula (b-2-1), diisocyanate corresponding to diamine represented by the compound represented by formula (b-2-2), and Diisocyanate corresponding to the diamine represented by the compound represented by formula (b-2-3) is mentioned. As the compound giving the structural unit (B-2-1), the compound giving the structural unit (B-2-2), and the compound giving the structural unit (B-2-3), the formula (b The compound represented by -2-1) (i.e., diamine), the compound represented by formula (b-2-2) (i.e., diamine), and the compound represented by formula (b-2-3) (i.e., diamine ) Is preferred.

As the compound to which the structural unit (B-2) is provided, only the compound to which the structural unit (B-2-1) is provided may be used, or only the compound to which the structural unit (B-2-2) is provided, or Only the compound which gives the structural unit (B-2-3) can also be used.

In addition, as the compound to give the structural unit (B-2), a combination of the compound to give the structural unit (B-2-1) and the compound to give the structural unit (B-2-2) may be used. A combination of the compound giving the unit (B-2-2) and the compound giving the structural unit (B-2-3) may be used, or the compound and the structural unit giving the structural unit (B-2-1) A combination of the compound giving (B-2-3) can also be used.

In addition, as a compound giving the structural unit (B-2), the compound giving the structural unit (B-2-1), the compound giving the structural unit (B-2-2), and the structural unit (B-2- It is also possible to use a combination of compounds to give 3).

The diamine component contains a compound that imparts the structural unit (B-1), preferably 10 to 50 mol%, more preferably 10 to 40 mol%, and still more preferably 15 to 30 mol% And particularly preferably 15 to 25 mol%.

The diamine component contains a compound that imparts the structural unit (B-2), preferably 50 to 90 mol%, more preferably 60 to 90 mol%, and even more preferably 70 to 85 mol% And particularly preferably 75 to 85 mol%.

The diamine component, in total, preferably contains 50 mol% or more, more preferably 70 mol% or more, in total, of the compound giving the constituent unit (B-1) and the compound giving the constituent unit (B-2) And more preferably 90 mol% or more, and particularly preferably 99 mol% or more. 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 of only the compound which gives the structural unit (B-1) and the compound which gives the structural unit (B-2).

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), and examples of the compound include the above-described aromatic diamine, alicyclic diamine, And aliphatic diamines, and derivatives thereof (diisocyanate, etc.).

The number of compounds other than the compound which imparts the structural unit (B-1) optionally contained in the diamine component and the compound which imparts the structural unit (B-2) may be one or two or more.

In the present invention, it is preferable that the 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 moles of the diamine component per 1 mole of the tetracarboxylic acid component.

In addition, in the present invention, in the production of the polyimide resin, in addition to the above-described tetracarboxylic acid component and diamine component, an end-sealing agent can also be used. As the terminal sealing agent, monoamines or dicarboxylic acids are preferable. The amount of the terminal sealing agent to be introduced is preferably 0.0001 to 0.1 mol, and particularly preferably 0.001 to 0.06 mol, per 1 mol of the tetracarboxylic acid component. Examples of monoamine end caps include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, and 3-methylbenzylamine , 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. are recommended. Among these, benzylamine and aniline can be used suitably. As the dicarboxylic acid terminal sealing agent, dicarboxylic acids are preferable, and a part thereof may be closed ring. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, Cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, and the like are recommended. Among these, phthalic acid and phthalic anhydride can be suitably used.

There is no restriction|limiting in particular in the method of making the above-mentioned tetracarboxylic acid component and a diamine component react, A well-known method can be used.

As a specific reaction method, (1) a tetracarboxylic acid component, a diamine component, and a reaction solvent are introduced into a reactor, stirred at room temperature to 80°C for 0.5 to 30 hours, and then heated to perform an imidation reaction, ( 2) After dissolving the diamine component and the reaction solvent in the reactor, the tetracarboxylic acid component is added and, if necessary, stirred at room temperature to 80° C. for 0.5 to 30 hours, and then heated to perform an imidation reaction, (3) A method of introducing a tetracarboxylic acid component, a diamine component, and a reaction solvent into a reactor and immediately raising the temperature to perform an imidation reaction, etc. are mentioned.

The reaction solvent used for production of the polyimide resin may be any one capable of dissolving the resulting polyimide without inhibiting the imidation reaction. For example, an aprotic solvent, a phenolic solvent, an ether solvent, a carbonate solvent, and the like can be mentioned.

Specific examples of the aprotic solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazoli Amide solvents such as dione and tetramethylurea, lactone solvents such as γ-butyrolactone and γ-valerolactone, phosphorus-containing amide solvents such as hexamethylphosphoricamide and hexamethylphosphinetriamide, dimethylsulfone , Sulfur-containing solvents such as dimethyl sulfoxide and sulfolane, ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone, amine solvents such as picoline and pyridine, 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, etc. are 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-methoxyethyl)ether. Oxyethoxy)ethyl] ether, tetrahydrofuran, and 1,4-dioxane.

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

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

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

In the above imidization reaction, a known imidization catalyst can be used. Examples of the imidation catalyst include a base catalyst or an acid catalyst.

As the base catalyst, pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine , Triethylenediamine, imidazole, N,N-dimethylaniline, N,N-diethylaniline, and other organic base catalysts, and inorganic bases such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogen carbonate and sodium hydrogen carbonate Catalysts.

Further, examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxyanic acid, terephthalic acid, benzenesulfonic acid, paratoluenesulfonic acid, naphthalenesulfonic acid, and the like. The imidation catalyst described above may be used alone or in combination of two or more.

Among the above, from the viewpoint of handling properties, it is preferable to use a base catalyst, more preferably an organic base catalyst, even more preferably triethylamine, and particularly preferably in combination with triethylamine and triethylenediamine. Do.

The temperature of the imidation reaction is preferably 120 to 250°C, more preferably 160 to 200°C, from the viewpoint of the reaction rate and suppression of gelation and the like. In addition, the reaction time is preferably 0.5 to 10 hours after the start of outflow of the generated 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 and an organic solvent of the present invention, and the polyimide resin is dissolved in the organic solvent.

The organic solvent is not particularly limited as long as the polyimide resin is dissolved, but it is preferable to use the above-described compounds alone or in combination of two or more as the reaction solvent used in the production of the polyimide resin.

The polyimide varnish of the present invention may be a polyimide solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or a diluent solvent may be added to the polyimide solution.

Since the polyimide resin of the present invention has solvent solubility, it can be obtained as a varnish of high concentration stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40 mass% of the polyimide resin of the present invention, and more preferably contains 10 to 30 mass%. The viscosity of the polyimide varnish is preferably 1 to 200 Pa·s, more preferably 5 to 150 Pa·s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer.

In addition, the polyimide varnish of the present invention is an inorganic filler, an adhesion promoter, a release agent, a flame retardant, an ultraviolet absorber, a surfactant, a leveling agent, an antifoaming agent, an optical brightening agent, a crosslinking agent, and within the range not impairing the required properties of the polyimide film. It may also contain various additives such as a polymerization initiator and a photosensitizer. That is, the polyimide resin of the present invention may be configured as a resin composition to which the above additives are added, if necessary.

The method for producing the polyimide varnish of the present invention is not particularly limited, and a known method can be applied.

As the ultraviolet absorber exemplified as the additive, any suitable ultraviolet absorber may be employed. Specific examples thereof include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzoate-based ultraviolet absorbers, triazine-based ultraviolet absorbers, hindered amine-based ultraviolet absorbers, inorganic particles-based ultraviolet absorbers, and other, analylide oxalate-based ultraviolet absorbers. And organic ultraviolet absorbers such as xena malonic acid ester ultraviolet absorbers. Only one type of ultraviolet absorber may be used, or two or more types may be used in combination. Among these, a benzotriazole-based ultraviolet absorber and a triazine-based ultraviolet absorber are preferable, and a benzotriazole-based ultraviolet absorber is more preferable.

The amount of the ultraviolet absorber to be added in the resin composition is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 5 parts by mass, and still more preferably 0.5 to 4 parts by mass per 100 parts by mass of the polyimide resin of the present invention. It is wealth. When the amount of the ultraviolet absorber is large, properties of the polyimide resin such as optical properties and heat resistance may be deteriorated, or haze may occur in the film.

In the present invention, the ultraviolet absorber can achieve the effect of the ultraviolet absorber in the resin composition. Accordingly, the compound added as the ultraviolet absorber may be present in the resin composition in the same structure, or the compound may be modified by heat treatment into a modified product that still has an effect of absorbing ultraviolet rays. In addition, it is preferable that the ultraviolet absorber is uniformly mixed with the polyimide resin of the present invention in the resin composition.

[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 colorless transparency and optical isotropy, and has a low elastic modulus. The 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, after applying the polyimide varnish of the present invention onto a smooth support such as a glass plate, a metal plate, or plastic, or forming a film, an organic solvent such as a reaction solvent or a diluting solvent contained in the varnish is heated. A method of removing by, etc. are mentioned. If necessary, a release agent may be previously applied to the surface of the support.

As a method of removing the organic solvent contained in the varnish by heating, the following method is preferable. That is, after evaporating the organic solvent at a temperature of 120°C or less to form a self-supporting film, the self-supporting film is peeled from the support, the end of the self-supporting film is fixed, and the temperature is above the boiling point of the used organic solvent It is preferable to dry in to prepare a polyimide film. In addition, it is preferable to dry it in a nitrogen atmosphere. The pressure in the dry atmosphere may be any of reduced pressure, normal pressure, and pressure. The heating temperature when drying the self-supporting film to prepare a polyimide film is not particularly limited, but is preferably 200 to 400°C.

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

The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration or 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 suitably used as a substrate for an image display device such as a liquid crystal display or an OLED display.

Example

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited at all by these Examples.

The solid content concentration of the polyimide varnish obtained in Examples and Comparative Examples and the respective physical properties of the polyimide film were measured by the methods shown below.

(1) solid content concentration

The solid content concentration was calculated from the mass difference of the sample before and after heating by heating the sample at 320° C. x 120 min with a small electric furnace "MMF-1" manufactured by Asone Corporation.

(2) film thickness

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

(3) Tensile modulus, tensile strength

Tensile modulus and tensile strength were measured in accordance with JIS K7127, using a tensile tester "Strograph VG-1E" manufactured by Dongyang Seiki Co., Ltd.

(4) Total light transmittance, yellow index (YI), haze

The total light transmittance, YI, and haze were measured using a color and turbidity simultaneous measuring instrument "COH400" manufactured by Nippon Electric Co., Ltd. The measurement of the total light transmittance and YI was based on JIS K7361-1:1997, and the measurement of haze was based on JIS K7136:2000.

(5) Thickness phase difference (Rth)

The thickness phase difference (Rth) was measured using an ellipsometer "M-220" manufactured by Japan Spectroscopic Co., Ltd. The value of the thickness phase difference at a measurement wavelength of 550 nm was measured. On the other hand, Rth is expressed by the following formula when the largest in-plane refractive index of the polyimide film is nx, the minimum is ny, the refractive index in the thickness direction is nz, and the film thickness is d.

Rth=[{(nx+ny)/2}-nz]×d

(6) Glass transition temperature (Tg)

Using the thermomechanical analysis device "TMA/SS6100" made by Hitachi Hi-Tech Science, in tension mode, the sample size is 2 mm × 20 mm, the load is 0.1 N, and the temperature rise rate is 10°C/min. Temperature sufficient to remove residual stress. The temperature was raised to remove residual stress, and then cooled to room temperature. Thereafter, 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 seen was determined as the glass transition temperature.

The tetracarboxylic acid component and diamine component used in Examples and Comparative Examples, and their abbreviations are as follows.

<Tetracarboxylic acid component>

HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.; compound represented by formula (a-1))

<Diamine component>

X-22-9409: Both-end amino-modified silicone oil "X-22-9409" (manufactured by Shin-Etsu Chemical Industries, Ltd.; compound represented by formula (b-1))

HFBAPP: 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane (manufactured by Seika Corporation; compound represented by formula (b-2-1))

BAPP: 2,2-bis [4-(4-aminophenoxy) phenyl] propane (manufactured by Seika Corporation; compound represented by formula (b-2-2))

TMDA: 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine (manufactured by Nippon Pure Chemical Industries, Ltd.; represented by formula (b-2-3) Compound)

BAPS: Bis [4-(4-aminophenoxy) phenyl] sulfone (made by Seika Corporation)

<Example 1>

In a 0.3L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen introduction pipe, cooling pipe, thermometer, and glass end cap, HFBAPP is 29.034g (0.056mol), X-22- 18.76 g (0.014 mol) of 9409, 50 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.), 0.039 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), triethylamine (manufactured by Kanto Chemical Co., Ltd.) 3.54g, under nitrogen atmosphere, stirred at 200rpm to obtain a solution. To this solution, 15.692 g (0.070 mol) of HPMDA and 13.5 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, respectively, and then heated with a mantle heater, and the temperature in the reaction system was increased over about 20 minutes. It was raised to 200°C. The distilled component was collected, and the temperature inside the reaction system was maintained at 200°C for 3 hours. After 78.76 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, the mixture was stirred at about 100°C for about 1 hour to obtain a homogeneous polyimide varnish having a solid content concentration of 30% by mass.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame, and the solvent was removed by drying for 2 hours in a nitrogen atmosphere at 230°C to obtain a film having a thickness of 30 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film.

<Example 2>

In a 0.5L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen inlet pipe, cooling pipe, thermometer, and glass end cap, 65.683g (0.160 mole) of BAPP, X-22- 9409 was 53.600 g (0.040 mol), γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) 200 g, and triethylamine (manufactured by Kanto Chemical Co., Ltd.) as a catalyst, 10.12 g, and stirred at 200 rpm under a nitrogen atmosphere to prepare a solution. Got it. To this solution, 144.834 g (0.200 mol) of HPMDA and 46.2 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, respectively, then heated with a mantle heater, and the temperature in the reaction system was increased over about 20 minutes. It was raised to 200°C. The distilled components were collected, and the temperature in the reaction system was maintained at 200°C for 5 hours. After 120.0 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, the mixture was stirred at about 100° C. for about 1 hour to obtain a uniform polyimide varnish having a solid content concentration of 30% by mass.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame, and the solvent was removed by drying for 2 hours in a nitrogen atmosphere at 230°C to obtain a film having a thickness of 30 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film.

<Example 3>

In a 0.5L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen inlet pipe, cooling pipe, thermometer, and glass end cap, TMDA was 14.906g (0.056 mole), X-22- 18.76 g (0.014 mol) of 9409, 30 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.), and 0.031 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), triethylamine (manufactured by Kanto Chemical Co., Ltd.) Was stirred at 3.54g, nitrogen atmosphere, 200rpm to obtain a solution. To this solution, 15.692 g (0.070 mol) of HPMDA and 10.4 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, and then heated with a mantle heater, and the temperature in the reaction system was increased over about 20 minutes. It was raised to 200°C. The distilled component was collected, and 10.91 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) was added while maintaining the temperature in the reaction system at 200°C for 2.5 hours, and stirring was continued for 50 minutes. After that, 10.7 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, and stirring was continued for 75 minutes. Then, 13.9 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, and stirring was continued for 4 hours. Finally, 35.24 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, followed by stirring at around 100°C for about 1 hour to obtain a homogeneous polyimide varnish having a solid content concentration of 30% by mass.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame, and the solvent was removed by drying for 2 hours in a nitrogen atmosphere at 230°C to obtain a film having a thickness of 24 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film.

<Example 4>

In a 3.0L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen inlet pipe, cooling pipe, thermometer and glass end cap, HFBAPP is 355.41g (0.684 mole), X-22- 295.347 g (0.216 mol) of 9409, 500 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.), and 0.501 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), triethylamine (manufactured by Kanto Chemical Co., Ltd.) The mixture was stirred at 45.54 g and 150 rpm under a nitrogen atmosphere to obtain a solution. To this solution, 201.96 g (0.900 mol) of HPMDA and 192.0 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, respectively, then heated with a mantle heater, and the temperature in the reaction system was increased over about 50 minutes. It was raised to 200°C. The distilled components were collected, and the temperature inside the reaction system was maintained at 200°C for 3.75 hours. Finally, 1205.9 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, followed by stirring at around 100°C for about 1 hour to obtain a homogeneous polyimide varnish having a solid content concentration of 30% by mass.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame, and the solvent was removed by drying at 190° C. for 20 minutes in an air atmosphere to obtain a film having a thickness of 38 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film.

<Example 5>

In a 0.3L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen introduction pipe, cooling pipe, thermometer, and glass end cap, HFBAPP is 28.708g (0.055 mole), X-22- 12.870 g (0.010 mol) of 9409, 44.9 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.), and 0.036 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.), triethylamine (manufactured by Kanto Chemical Co., Ltd.) Was stirred at 3.29 g and 200 rpm under a nitrogen atmosphere to obtain a solution. To this solution, 14.586 g (0.065 mol) of HPMDA and 11.2 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, and then heated with a mantle heater, and the temperature in the reaction system was increased over about 20 minutes. It was raised to 180°C. The distilled components were collected, and the temperature in the reaction system was maintained at 180°C for 4 hours. After 69.3 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, the mixture was stirred at about 100°C for about 1 hour to obtain a homogeneous polyimide varnish having a solid content concentration of 30% by mass.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame, dried at 240° C. for 10 minutes, and then dried for 10 minutes at 250° C. to remove the solvent to obtain a film having a thickness of 36 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film.

<Example 6>

Example 1 to the polyimide varnish obtained in the same manner as in Example 1, except that 0.5 parts by mass of Tinuvin234 (manufactured by BASF Japan Co., Ltd., a benzotriazole-based ultraviolet absorber) as an ultraviolet absorber was added to 100 parts by mass of the polyimide resin. A film having a thickness of 33 μm was obtained by the same method as described above. Table 1 shows the evaluation results of this polyimide film.

<Example 7>

Example 1 to the polyimide varnish obtained in the same manner as in Example 1, except that 4.0 parts by mass of Tinuvin234 (manufactured by BASF Japan Corporation, a benzotriazole-based ultraviolet absorber) as an ultraviolet absorber was added to 100 parts by mass of the polyimide resin. A film having a thickness of 25 μm was obtained by the same method as described above. Table 1 shows the evaluation results of this polyimide film.

<Comparative Example 1>

In a 0.3L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen inlet pipe, cooling pipe, thermometer, and glass end cap, HFBAPP was 41.477g (0.080 mole), γ-butyro. 70 g of lactone (manufactured by Mitsubishi Chemical Corporation), and 0.405 g of triethylamine (manufactured by Kanto Chemical Corporation) as a catalyst, were stirred at 200 rpm in a nitrogen atmosphere to obtain a solution. To this solution, 17.952 g (0.080 mol) of HPMDA and 19.1 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, and then heated with a mantle heater, and the temperature in the reaction system was increased over about 20 minutes. It was raised to 180°C. The distilled component was collected, and 89.12 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added while maintaining the temperature in the reaction system at 180° C. for 4 hours, followed by stirring at around 100° C. for about 1 hour. A uniform polyimide varnish having a solid content concentration of 20% by mass was obtained.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame and dried at 230° C. under nitrogen atmosphere for 2 hours to remove the solvent to obtain a film having a thickness of 35 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film. On the other hand, about this polyimide film, Tg was not measured.

<Comparative Example 2>

In a 0.3L five-hole glass round bottom flask equipped with stainless steel half-moon stirring blades, nitrogen introduction pipe, cooling pipe, thermometer, and glass end cap, BAPS is 20.76g (0.048 mole), X-22- 16.408 g (0.012 mol) of 9409, 32 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.), and 3.04 g of triethylamine (manufactured by Kanto Chemical Co., Ltd.) as a catalyst, were stirred at 200 rpm under a nitrogen atmosphere to obtain a solution. . To this solution, 13.450 g (0.060 mol) of HPMDA and 18 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added in batches, and then heated with a mantle heater, and the temperature in the reaction system was increased to 200 over about 20 minutes. Raised to ℃. The distilled components were collected, and the temperature in the reaction system was maintained at 200°C for 3.5 hours. After 62.0 g of N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added, the mixture was stirred at about 100°C for about 1 hour to obtain a uniform polyimide varnish having a solid content concentration of 30% by mass.

Subsequently, the obtained polyimide varnish was applied onto a PET substrate, held at 100° C. for 30 minutes, and the solvent was volatilized to obtain a colorless and transparent primary dry film having self-support. Again, this film was fixed to a stainless steel frame and dried at 230° C. in a nitrogen atmosphere for 2 hours to remove the solvent to obtain a film having a thickness of 46 μm. The disappearance of the raw material peak and the appearance of the peak derived from the imide skeleton were confirmed by FT-IR analysis of the obtained film. Table 1 shows the evaluation results of this polyimide film.

[Table 1]

As shown in Table 1, the films of Examples 1 to 7 were excellent in colorless transparency and optical isotropy, and had low elastic modulus.

From the contrast between the film of Example 1 and the film of Comparative Example 1, it was confirmed that the polyimide resin contained the structural unit (B-1), thereby reducing the elastic modulus.

From the contrast between the films of Examples 1 to 7 and the film of Comparative Example 2, it was confirmed that the polyimide resin contained the structural unit (B-2), thereby showing excellent colorless transparency.

In addition, from the contrast between the film of Example 1 and the film of Comparative Example 1, it was confirmed that the optical isotropy of the film was improved according to the polyimide resin containing the structural unit (B-1), and the films of Examples 1 to 7 From the contrast between the film of Comparative Example 2 and the film of Comparative Example 2, it was confirmed that the polyimide resin contained both the constituent unit (B-1) and the constituent unit (B-2), and particularly excellent expression of optical isotropy.

Claims (8)

As a polyimide resin having a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,
Constituent unit A includes a structural unit (A-1) derived from a compound represented by the following formula (a-1),
Structural unit B is a structural unit (B-1) derived from a compound represented by the following formula (b-1), and a structural unit (B-2-1) derived from a compound represented by the following formula (b-2-1). 1), a structural unit derived from a compound represented by the following formula (b-2-2) (B-2-2), and a structural unit derived from a compound represented by the following formula (b-2-3) (B A polyimide resin containing at least one structural unit (B-2) selected from the group consisting of -2-3).
[Formula 1]

(In formula (b-1),
R ₁ to R ₄ are each independently a monovalent aliphatic group or a monovalent aromatic group,
Z ₁ and Z ₂ are each independently a divalent aliphatic group or a divalent aromatic group,
r is a positive integer.) The method of claim 1,
The polyimide resin, wherein the proportion of the structural unit (A-1) in the structural unit A is 50 mol% or more. The method according to claim 1 or 2,
The proportion of the structural unit (B-1) in the structural unit B is 10 to 50 mol%,
The polyimide resin, wherein the proportion of the structural unit (B-2) in the structural unit B is 50 to 90 mol%. The method according to any one of claims 1 to 3,
A polyimide resin in which the structural unit (B-2) is a structural unit (B-2-1). The method according to any one of claims 1 to 3,
The polyimide resin in which the structural unit (B-2) is a structural unit (B-2-2). The method according to any one of claims 1 to 3,
The polyimide resin in which the structural unit (B-2) is a structural unit (B-2-3). A polyimide varnish obtained by dissolving the polyimide resin according to any one of claims 1 to 6 in an organic solvent. A polyimide film containing the polyimide resin according to any one of claims 1 to 6.