TW202222973A - Polyimide resin, polyimide varnish, and polyimide film - Google Patents

Abstract

A polyimide resin containing a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A includes a structural unit (A1) derived from a tetracarboxylic dianhydride having two norbornane skeletons within the molecule, the structural unit B includes a structural unit (B1) derived from a compound represented by formula (b1) shown below, and the proportion of the structural unit (B1) among all of the structural units B is at least 35 mol% but not more than 95 mol%.

Description

Polyimide resin, polyimide varnish and polyimide film

The present invention relates to polyimide resins, polyimide varnishes and polyimide films.

Polyimide resins have been studied for various applications in the fields of electrical and electronic parts. For example, it is expected to replace the glass substrate used in image display devices such as liquid crystal displays and OLED displays with plastic substrates for the purpose of reducing the weight and flexibility of the devices, which is suitable for the research on polyimide films of the plastic substrates. is already in progress. Various optical properties are required for thin films used in image display device applications. For example, when light emitted from a display element is emitted through a plastic substrate, the plastic substrate requires transparency.

In order to satisfy the above-mentioned properties, the development of polyimide resins of various compositions has been carried out. For example, Patent Document 1 discloses that, in order to obtain a polyimide film having excellent transparency and high heat resistance, an acid dianhydride having a norbornane skeleton and 9,9-bis(4-aminophenyl) as a diamine component are disclosed. ) The polyimide film of the structure formed by the combination of tallow. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2019-059959

[The problem to be solved by the invention]

In the case of the polyimide film, it is required to replace the glass substrate, and transparency is required. Here, when an image display device is manufactured, for example, a heat treatment is performed in a state where an inorganic film is laminated on a polyimide film, so the escape gas generated from the polyimide film accumulates in the polyimide film and the inorganic film, so the polyimide film may be colored such as yellowing in some cases. Accordingly, the polyimide thin film is required to have heat resistance which suppresses coloration when exposed to high temperature in the state where the inorganic film is laminated. In addition, when manufacturing an image display device, for example, the process temperature may exceed 400°C. Therefore, the polyimide film used as a substrate is required to be heat resistant to a high temperature of 400°C or higher. A polyimide film with a high glass transition temperature (Tg) and excellent heat resistance may cause defects such as cracks in the inorganic film when exposed to high temperature in a state where the inorganic film is laminated. Accordingly, when the polyimide thin film is exposed to high temperature in a state where the inorganic film is laminated, heat resistance such that defects such as cracks are not generated in the inorganic film is required. The present invention is made in view of such a situation, and an object of the present invention is to provide a polyimide resin and a polyimide varnish which can obtain a polyimide film excellent in transparency and heat resistance when an inorganic film is laminated, and Provides a polyimide film excellent in transparency and heat resistance when an inorganic film is laminated. [Means of Solving Problems]

The present inventors have found that a polyimide resin containing a structural unit derived from a tetracarboxylic dianhydride having two norbornane skeletons in the molecule and a structural unit derived from a specific diamine can solve the above-mentioned problems, and the invention has been completed.

＜2＞如＜1＞所記載之聚醯亞胺樹脂，其中，構成單元(A1)包含選自由來自下式(a11)表示之化合物之構成單元(A11)、來自下式(a12)表示之化合物之構成單元(A12)、來自下式(a13)表示之化合物之構成單元(A13)、及來自下式(a14)表示之化合物之構成單元(A14)構成之群組中之至少1種。 [化2]

＜3＞如＜1＞或＜2＞所記載之聚醯亞胺樹脂，其中，構成單元A更包含構成單元(A2)，且構成單元(A2)包含選自由來自下式(a21)表示之化合物之構成單元(A21)、及來自下式(a22)表示之化合物之構成單元(A22)構成之群組中之至少1種。 [化3]

＜4＞如＜1＞~＜3＞中任一項所記載之聚醯亞胺樹脂，其中，構成單元B更包含構成單元(B2)，且構成單元(B2)包含選自由來自下式(b21)表示之化合物之構成單元(B21)、來自下式(b22)表示之化合物之構成單元(B22)、來自下式(b23)表示之化合物之構成單元(B23)、及來自下式(b24)表示之化合物之構成單元(B24)構成之群組中之至少1種。 [化4]

[化5]

[化6]

[化7]

＜5＞如＜4＞所記載之聚醯亞胺樹脂，其中，構成單元(B2)包含來自下式(b21)表示之化合物之構成單元(B21)。 [化8]

＜6＞一種聚醯亞胺清漆，係將如＜1＞~＜5＞中任一項所記載之聚醯亞胺樹脂溶解於有機溶劑而成。 ＜7＞一種聚醯亞胺薄膜，含有如＜1＞~＜5＞中任一項所記載之聚醯亞胺樹脂。 ＜8＞如＜7＞所記載之聚醯亞胺薄膜，其中，依據JIS K7127：1999以夾具間距離：50mm、試驗片尺寸：10mm×70mm、拉伸速度：20mm/min及測定溫度：23℃為條件測定之拉伸斷裂伸長度為9.5%以上。 ＜9＞如＜7＞或＜8＞所記載之聚醯亞胺薄膜，其中，依據JIS K7136：2000測定之全光線透射率為80%以上。 ＜10＞如＜7＞~＜9＞中任一項所記載之聚醯亞胺薄膜，其係作為構成顯示裝置之透明性基板使用。 ＜11＞一種聚醯亞胺薄膜之製造方法，包含下列步驟： 將如＜6＞所記載之聚醯亞胺清漆塗佈成或成形成薄膜狀後，將有機溶劑去除。 ＜12＞一種圖像顯示裝置，具備如＜7＞~＜10＞中任一項所記載之聚醯亞胺薄膜作為透明性基板。 [發明之效果] That is, the present invention relates to the following <1> to <12>. <1> A polyimide resin containing a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from a diamine; the structural unit A includes a tetracarboxylic acid dibasic derived from two norbornane skeletons in the molecule Structural unit (A1) of anhydride, Structural unit B includes structural unit (B1) derived from a compound represented by the following formula (b1), The ratio of the structural unit (B1) in Structural unit B is 35 mol % or more and 95 mol % %the following. [hua 1]

<2> The polyimide resin according to <1>, wherein the structural unit (A1) includes a structural unit (A11) selected from the group consisting of a compound represented by the following formula (a11), a At least one of the group consisting of the structural unit (A12) of the compound, the structural unit (A13) derived from the compound represented by the following formula (a13), and the structural unit (A14) derived from the compound represented by the following formula (a14). [hua 2]

<3> The polyimide resin according to <1> or <2>, wherein the structural unit A further comprises a structural unit (A2), and the structural unit (A2) contains a compound selected from the group consisting of the following formula (a21) At least one of the group consisting of the structural unit (A21) of the compound and the structural unit (A22) of the compound represented by the following formula (a22). [hua 3]

<4> The polyimide resin according to any one of <1> to <3>, wherein the structural unit B further comprises a structural unit (B2), and the structural unit (B2) contains a structure selected from the group consisting of the following formula ( The structural unit (B21) of the compound represented by b21), the structural unit (B22) derived from the compound represented by the following formula (b22), the structural unit (B23) derived from the compound represented by the following formula (b23), and the structural unit (B24) derived from the following formula (b24) At least one of the group consisting of the structural unit (B24) of the compound represented by ). [hua 4]

[hua 5]

[hua 6]

[hua 7]

<5> The polyimide resin according to <4>, wherein the structural unit (B2) includes the structural unit (B21) derived from the compound represented by the following formula (b21). [hua 8]

<6> A polyimide varnish prepared by dissolving the polyimide resin according to any one of <1> to <5> in an organic solvent. <7> A polyimide film comprising the polyimide resin according to any one of <1> to <5>. <8> The polyimide film according to <7>, wherein the distance between the jigs: 50 mm, the test piece size: 10 mm×70 mm, the tensile speed: 20 mm/min, and the measurement temperature: 23 mm according to JIS K7127:1999 The tensile elongation at break measured at ℃ is 9.5% or more. <9> The polyimide film according to <7> or <8>, wherein the total light transmittance measured in accordance with JIS K7136:2000 is 80% or more. <10> The polyimide film according to any one of <7> to <9>, which is used as a transparent substrate constituting a display device. <11> A method for producing a polyimide film, comprising the steps of: after coating or forming the polyimide varnish as described in <6> into a film, the organic solvent is removed. <12> An image display device including the polyimide film according to any one of <7> to <10> as a transparent substrate. [Effect of invention]

According to the present invention, a polyimide resin and a polyimide varnish that can obtain a polyimide film excellent in transparency and heat resistance when an inorganic film is laminated can be provided, and a polyimide resin and a polyimide varnish that can provide transparency and when an inorganic film is laminated can be provided Polyimide film with excellent heat resistance.

A mode for implementing the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and does not limit the content of the present invention. The present invention can be appropriately changed and implemented within the scope of its gist. In this embodiment, the definition defined as ideal can be arbitrarily adopted, and it can be said that it is better by combining the contents of ideal. In this embodiment, the description of "XX~YY" means "XX or more and YY or less".

[Polyimide resin] The polyimide resin of the present invention is a polyimide resin containing a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from a diamine; the structural unit A contains two norbornane skeletons derived from the molecule The structural unit (A1) of the tetracarboxylic dianhydride, the structural unit B contains the structural unit (B1) derived from the compound represented by the following formula (b1), and the ratio of the structural unit (B1) in the structural unit B is 35 mol% More than 95 mol% or less.

[Chemical 9]

The reason why a polyimide film excellent in transparency and heat resistance when an inorganic film is laminated by using the polyimide resin of the present invention has not yet been elucidated, but it is considered that it has a norbornane skeleton and non-linearity. In addition, the molecular weight is small, that is, the structural unit (B1) that increases the concentration of imide groups, so the transparency can be kept good, and the toughness and heat resistance can be improved at the same time, so the transparency and the heat resistance when the inorganic film is laminated (Suppression of coloration, suppression of cracks in inorganic films) is excellent.

<Construction Unit A> The structural unit A is a structural unit derived from tetracarboxylic dianhydride in the polyimide resin. The structural unit A contains the structural unit (A1) derived from the tetracarboxylic dianhydride which has two norbornane skeletons in a molecule|numerator. From the viewpoint of heat resistance, transparency, and optical isotropy, the structural unit (A1) preferably includes a structural unit (A11) derived from a compound represented by the following formula (a11) and a structure derived from a compound represented by the following formula (a12) At least one of the group consisting of the unit (A12), the structural unit (A13) derived from the compound represented by the following formula (a13), and the structural unit (A14) derived from the compound represented by the following formula (a14), it is considered that the molecular The viewpoint that the skeleton is more rigid and the heat resistance is further improved includes a constituent unit (A11) derived from a compound represented by the following formula (a11), a constituent unit (A12) derived from a compound represented by the following formula (a12), and More preferably, at least one of the group consisting of the structural unit (A14) of the compound represented by the formula (a14) includes a structural unit (A11) derived from the compound represented by the following formula (a11), and a structural unit (A11) derived from the following formula (a14) At least one of the group consisting of the structural unit (A14) of the compound represented by ) is even more preferable, and it is even more preferable to include the structural unit (A11) derived from the compound represented by the following formula (a11).

[Chemical 10]

Structural unit A includes structural unit (A1) derived from tetracarboxylic dianhydride having two norbornane skeletons in the molecule, so that the heat resistance, transparency and optical isotropy of the obtained polyimide film can be improved .

The structural unit A may further include the structural unit (A2) in addition to the structural unit (A1). The structural unit (A2) includes, for example, at least 1 selected from the group consisting of the structural unit (A21) derived from the compound represented by the following formula (a21) and the structural unit (A22) derived from the compound represented by the following formula (a22). kind.

[Chemical 11]

The compound represented by the formula (a21) is biphenyltetracarboxylic dianhydride (BPDA), and specific examples thereof include 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a211s) ), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) represented by the following formula (a211a), 2,2',3,3'-biphenyl represented by the following formula (a211i) Tetracarboxylic dianhydride (i-BPDA). Among them, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) represented by the following formula (a211s) is preferable.

[Chemical 12]

The ratio of the structural unit (A1) in the structural unit A is preferably 40 mol % or more, more preferably 60 mol % or more, and 70 mol % or more in view of heat resistance, transparency and optical isotropy. More preferably, it is 80 mol% or more, still more preferably, it is 85 mol% or more, still better, it is 90 mol% or more, and it is more preferably 95 mol% or more, and it is 99 mol% or more. better. The upper limit of the ratio is not particularly limited, but is 100 mol % or less. In addition, when the structural unit A further includes the structural unit (A2), the ratio of the structural unit (A2) in the structural unit A is preferably 60 mol % or less, and 40 mol % or less from the viewpoint of heat resistance, transparency, and optical isotropy. Molar % or less is more preferred, 30 mol % or less is still better, 20 mol % or less is still more preferred, 15 mol % or less is still more preferred, 10 mol % or less is still more preferred, 5 mol % or less Less than 1 mol % is more preferable, and less than 1 mol % is more preferable. The lower limit value of the ratio is not particularly limited, but is 0.01 mol % or more.

The structural unit A may include structural units other than the structural unit (A1) and the structural unit (A2). The tetracarboxylic dianhydride that provides such a structural unit is not particularly limited, and examples thereof include 4,4'-oxydiphthalic anhydride, pyromellitic dianhydride, and 4,4'-(hexafluoroiso Aromatic tetracarboxylic dianhydride such as propyl) diphthalic anhydride (only, excluding compounds represented by formula (a21) or (a22)); 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1 , Alicyclic tetracarboxylic dianhydrides such as 2,3,4-cyclobutanetetracarboxylic dianhydride (only, excluding compounds represented by any one of formulae (a11) to (a14)); and 1,2,3 , 4-butane tetracarboxylic dianhydride and other aliphatic tetracarboxylic dianhydrides. In addition, in this specification, aromatic tetracarboxylic dianhydride means tetracarboxylic dianhydride containing one or more aromatic rings, and alicyclic tetracarboxylic dianhydride means containing one or more alicyclic rings and does not contain aromatic Cyclic tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride mean tetracarboxylic dianhydride containing neither aromatic ring nor alicyclic ring. The structural unit arbitrarily included in the structural unit A may be one type or two or more types.

<Construction unit B> The structural unit B is a structural unit derived from a diamine that occupies in the polyimide resin. The structural unit B includes the structural unit (B1) derived from the compound represented by the following formula (b1).

[Chemical 13]

The compound represented by formula (b1) is 1,3-phenylenediamine. By including the structural unit (B1), the structural unit B can improve the toughness while maintaining the heat resistance.

The ratio of the structural unit (B1) in the structural unit B is 35 mol % or more, preferably 40 mol % or more, more preferably 45 mol % or more, from the viewpoint of improving the heat resistance when the inorganic film is laminated. More preferably, it is 50 mol % or more, and even more preferably, it is 60 mol % or more. The ratio of the structural unit (B1) in the structural unit B is 95 mol % or less, preferably 90 mol % or less, and 85 mol % from the viewpoint of improving polymerizability, solubility, transparency, and optical isotropy % or less, still more preferably 80 mol % or less, still more preferably 75 mol % or less.

The structural unit B may include structural units other than the structural unit (B1). The structural unit B preferably includes the structural unit (B2) in addition to the structural unit (B1). The constitutional unit (B2) preferably contains, for example, a constitutional unit (B21) derived from a compound represented by the following formula (b21), a constitutional unit (B22) derived from a compound represented by the following formula (b22), a constitutional unit (B22) derived from a compound represented by the following formula (b23) At least one species from the group consisting of the structural unit (B23) of the compound and the structural unit (B24) of the compound represented by the following formula (b24), from the viewpoint of making the molecular skeleton more rigid and improving heat resistance, including More preferably, at least one selected from the group consisting of a structural unit (B21) derived from a compound represented by the following formula (b21) and a structural unit (B23) derived from a compound represented by the following formula (b23), including those derived from the following formula The structural unit (B21) of the compound represented by (b21) is still more preferable. When the structural unit B includes the structural unit (B2), especially the heat resistance is improved, and the optical isotropy is further improved. Moreover, by the structural unit (B2), the solubility of the resin after imidization can be improved, and polymerization can be performed more efficiently.

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17]

When the structural unit B further comprises the structural unit (B2), the ratio of the structural unit (B2) in the structural unit B is preferably 5 mol % or more, more preferably 10 mol % or more, more preferably 15 mol % or more , which is more than 20 mol % and even better, and more preferably contains more than 25 mol %. The upper limit of the ratio is 65 mol % or less, preferably 60 mol % or less, more preferably 55 mol % or less, even more preferably 50 mol % or less, and even more preferably 40 mol % or less. When the structural unit B further includes the structural unit (B2), the ratio of the total of the structural unit (B1) and the structural unit (B2) in the structural unit B is preferably 50 mol % or more, more preferably 70 mol % or more, and is More preferably 90 mol % or more, more preferably 95 mol % or more, still more preferably 99 mol % or more. The upper limit of the ratio of the total of the structural unit (B1) and the structural unit (B2) in the structural unit B is not particularly limited, but is, for example, 100 mol % or less. The structural unit B may be composed of only the structural unit (B1) and the structural unit (B2). When the structural unit B further includes the structural unit (B2), the molar ratio [(B1)/(B2)] of the structural unit (B1) in the structural unit B and the structural unit (B2) in the structural unit B considers transparency and optical isotropy. , From the viewpoint of improving toughness and heat resistance, it should be 35/65~95/5, 40/60~90/10 is better, 45/55~85/15 is better, 50/50~80/20 Even better, 60/40~75/25 is even better.

The structural unit B may include structural units other than the structural unit (B1) and the structural unit (B2). The diamine that provides such a structural unit is not particularly limited, and examples thereof include 1,4-phenylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl- 4,4'-diamine, 4,4'-diaminodiphenyl ether, 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl ether, 4,4'- Diaminodiphenylmethane, 4,4'-diaminobenzylaniline, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H -Indene-5-amine, α,α'-bis(4-aminophenyl)-1,4-dicumene, N,N'-bis(4-aminophenyl)terephthalic acid Amine, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 2,2-bis(4 Aromatic diamines such as -(4-aminophenoxy)phenyl)hexafluoropropane (only, excluding compounds represented by any one of formulae (b1), (b21) to (b24)); 1,3- Alicyclic diamines such as bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine. In addition, in this specification, an aromatic diamine means a diamine containing one or more aromatic rings, an alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, and an aliphatic diamine It means a diamine containing neither aromatic ring nor alicyclic ring. The structural unit arbitrarily included in the structural unit B may be one type or two or more types.

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

The polyimide resin may contain a structure other than the polyimide chain (the structure in which the structural unit A and the structural unit B are bonded by an imide). As a structure other than a polyimide chain which can be contained in a polyimide resin, the structure etc. which contain an amide bond are mentioned, for example. The polyimide resin preferably contains a polyimide chain (a structure in which the constituent unit A and the constituent unit B are bonded by imide) as the main structure. Therefore, the ratio of the polyimide chain in the polyimide resin is preferably 50 mass % or more, more preferably 70 mass % or more, still more preferably 90 mass % or more, particularly preferably 99 mass % or more, and , is 100 mass % or less. The polyimide resin may also consist only of polyimide chains.

The polyimide resin composition containing the above-mentioned polyimide resin can form a polyimide film with excellent toughness and heat resistance while maintaining transparency and optical isotropy. The polyimide film has ideal physical properties. as described below.

When the polyimide resin is made into a film with a thickness of 10 μm, the total light transmittance should be more than 80%, more preferably more than 85%, more preferably more than 88%, more preferably more than 88.5%, and 89% % or more is better. When the polyimide resin is made into a film with a thickness of 10 μm, the yellowness index (YI) is preferably 10.0 or less, more preferably 5.0 or less, more preferably 3.0 or less, still more preferably 2.5 or less, and more preferably 2.0 or less good. The absolute value of the thickness retardation (Rth) is preferably 200 nm or less, more preferably 180 nm or less, even more preferably 160 nm or less, and even more preferably 140 nm or less, when the polyimide resin is made into a film with a thickness of 10 μm.

Moreover, the mechanical properties and heat resistance of the film which can be formed using the said polyimide resin are also favorable, and have the following desirable physical property values. When the polyimide resin is made into a film with a thickness of 10 μm, the tensile strength is preferably 70 MPa or more, more preferably 80 MPa or more, and even more preferably 90 MPa or more. When the polyimide resin is made into a film with a thickness of 10 μm, the tensile modulus of elasticity is preferably 1.0 GPa or more, more preferably 1.5 GPa or more, more preferably 2.0 GPa or more, and even more preferably 2.3 GPa or more. The tensile elongation at break is preferably 9.5% or more, more preferably 10.0% or more, and even more preferably 10.5% or more, when the polyimide resin is made into a film with a thickness of 10 μm. The upper limit of the tensile elongation at break is preferably 20.0% or less, more preferably 15.0% or less, and even more preferably 13.5% or less. The glass transition temperature (Tg) is preferably 380°C or higher, more preferably 400°C or higher, and even more preferably 410°C or higher. The 5% weight reduction temperature (Td5%) is preferably 460°C or higher, more preferably 470°C or higher, and even more preferably 480°C or higher. The heat resistance when laminating an inorganic film is to form a SiO ₂ film with a thickness of 300 nm on the polyimide film by sputtering, and then form an ITO (indium tin oxide) film with a thickness of 1230 nm on it to make a laminated film. In order to prevent cracks, yellowing and other defects in the laminated film by "annealing treatment at 400°C for 1 hour", and in order to prevent cracks and yellowing in the laminated film by "annealing treatment at 420°C for 1 hour" Change and other defects are better. In addition, the said physical-property value in this invention can be measured by the method described in an Example specifically.

<Method for producing polyimide resin> The polyimide resin of the present invention can be produced by reacting a tetracarboxylic acid component containing a compound providing the above-mentioned structural unit (A1) with a compound providing the above-mentioned structural unit (B1).

The compound that provides the structural unit (A1) can be a compound represented by any one of the formulae (a11) to (a14), but it is not limited thereto, and a derivative thereof may be also provided within the scope of providing the same structural unit. Examples of the derivatives include tetracarboxylic acids corresponding to tetracarboxylic dianhydrides represented by any one of formula (a11) to formula (a14), and alkyl esters of the tetracarboxylic acids. Among them, tetracarboxylic dianhydride represented by formula (a11) is suitable.

A tetracarboxylic-acid component may contain the compound which provides a structural unit (A2) in addition to the compound which provides a structural unit (A1). The compound that provides the structural unit (A2) includes the compound represented by the formula (a21), the compound represented by the formula (a22), and the like, but is not limited thereto, and a derivative thereof may be used within the scope of providing the same structural unit.

The tetracarboxylic acid component preferably contains 40 mol% or more of the compound providing the constituent unit (A1), more preferably 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, More preferably, it contains 85 mol% or more, more preferably contains 90 mol% or more, more preferably contains 95 mol% or more, and more preferably contains 99 mol% or more. The upper limit of the ratio is not particularly limited, but is 100 mol % or less.

A tetracarboxylic-acid component may contain arbitrary compounds other than the compound which provides a structural unit (A1) and the compound which provides a structural unit (A2). Such arbitrary compounds include the above-mentioned aromatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, and derivatives thereof (tetracarboxylic acids, alkanes of tetracarboxylic acids) base ester, etc.). The compound arbitrarily contained in a tetracarboxylic-acid component may be 1 type, and may be 2 or more types.

The compound that provides the structural unit (B1) includes the compound represented by the formula (b1), but it is not limited thereto, and a derivative thereof may be also provided within the scope of providing the same structural unit. Examples of the derivatives include diisocyanates corresponding to the compounds represented by the formula (b1). The compound providing the structural unit (B1) is preferably a compound represented by the formula (b1) (ie, a diamine). A diamine component may contain the compound which provides a structural unit (B2) in addition to the compound which provides a structural unit (B1). The compound that provides the structural unit (B2) includes the compound represented by the formula (b21), the compound represented by the formula (b22), the compound represented by the formula (b23), the compound represented by the formula (b24), etc. Within the scope of the same constituent unit, derivatives thereof may also be used. Examples of the derivatives include diisocyanates corresponding to the compound represented by the formula (b21), the compound represented by the formula (b22), the compound represented by the formula (b23), and the compound represented by the formula (b24). The compound providing the constituent unit (B2) is preferably a compound represented by the formula (b21), a compound represented by the formula (b22), a compound represented by the formula (b23), and a compound represented by the formula (b24) (ie, a diamine).

The diamine component contains 35 mol% or more of the compound providing the constituent unit (B1), preferably 40 mol% or more, more preferably 45 mol% or more, more preferably 50 mol% or more, and 60 mol% % or more is better. The upper limit of the ratio is 95 mol % or less, preferably 90 mol % or less, more preferably 85 mol % or less, still more preferably 80 mol % or less, and even more preferably 75 mol % or less. When the diamine component contains the compound providing the structural unit (B2), it is preferable to contain the compound providing the structural unit (B2) in an amount of 5 mol% or more, more preferably 10 mol% or more, more preferably 15 mol% or more, More preferably, it contains more than 20 mol %, and even more preferably contains more than 25 mol %. The upper limit of the ratio is 65 mol % or less, preferably 60 mol % or less, more preferably 55 mol % or less, even more preferably 50 mol % or less, and even more preferably 40 mol % or less. When the diamine component contains the compound providing the structural unit (B2), the compound providing the structural unit (B1) and the compound providing the structural unit (B2) are preferably contained in a total of 50 mol% or more, more preferably 70 mol% or more, including More preferably more than 90 mol%, more preferably more than 95 mol%, more preferably more than 99 mol%. The upper limit is not particularly limited, and the total of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) in the diamine component is, for example, 100 mol % or less. The diamine component may be composed of only the compound providing the structural unit (B1) and the compound providing the structural unit (B2). In the diamine component, the molar ratio [(B1)/(B2)] of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) can be considered for polymerizability, solubility, transparency, and optical isotropy. , From the viewpoint of improving toughness and heat resistance, it should be 35/65~95/5, 40/60~90/10 is better, 45/55~85/15 is better, 50/50~80/20 Even better, 60/40~75/25 is even better.

The diamine component may further contain arbitrary compounds other than the compound providing the structural unit (B1) and the compound providing the structural unit (B2). As such an arbitrary compound, the said aromatic diamine, alicyclic diamine, and aliphatic diamine, and these derivatives (diisocyanate etc.) are mentioned. The compound arbitrarily contained in the diamine component may be one type or two or more types.

In the production of the polyimide resin of the present invention, the feeding amount ratio of the tetracarboxylic acid component and the diamine component used in the production of the polyimide resin is preferably 1 mole of the diamine component relative to 1 mole of the tetracarboxylic acid component. It is 0.9~1.1 moles.

Moreover, in the manufacture of the polyimide resin of the present invention, in addition to the aforementioned tetracarboxylic acid component and diamine component, a terminal blocking agent may be used for the manufacture of the polyimide resin. The terminal blocking agent is preferably a monoamine or a dicarboxylic acid. The feed amount of the introduced end capping agent is preferably 0.0001-0.1 mol, more preferably 0.001-0.06 mol, relative to 1 mol of the tetracarboxylic acid component. Examples of monoamine-based terminal blocking agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3- Methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc., preferably benzylamine, aniline. The dicarboxylic acid-based terminal blocking agent is preferably a dicarboxylic acid, 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 Alkane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc., preferably phthalic acid and phthalic anhydride.

The method of making the said tetracarboxylic-acid component and a diamine component react is not specifically limited, A well-known method can be used. Specific reaction methods include: (1) The tetracarboxylic acid component, the diamine component, and the reaction solvent are fed into the reactor, stirred at 0 to 10° C. for 0.5 to 30 hours, and then heated to carry out the imidization reaction. Method, (2) After the diamine component and the reaction solvent are fed into the reactor and dissolved, the tetracarboxylic acid component is fed, and stirred at 0 to 10° C. for 0.5 to 30 hours as required, and then the temperature is raised to implement imide (3) The tetracarboxylic acid component, the diamine component, and the reaction solvent are fed into the reactor, and the temperature is immediately raised to carry out the imidization reaction.

The reaction solvent used for the production of the polyimide resin may be one that can dissolve the produced polyimide without interfering with the imidization reaction. For example, an aprotic solvent, a phenol type solvent, an ether type solvent, a carbonate type solvent, etc. are mentioned.

Specific examples of the aprotic solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), N-methylcaprolactone amide-based solvents such as amide, 1,3-dimethylimidazolidinone, and tetramethylurea; lactone-based solvents such as γ-butyrolactone (GBL) and γ-valerolactone; hexamethylphosphamide , hexamethylphosphine triamide and other phosphorus-containing amide solvents; dimethyl sulfite, dimethyl sulfoxide, cyclobutane and other sulfur-containing solvents; acetone, cyclohexanone, methyl cyclohexanone and other ketones solvents; amine-based solvents such as picoline and pyridine; ester-based solvents such as acetic acid (2-methoxy-1-methylethyl ester), and the like.

Specific examples of the phenolic solvent include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, etc. Specific examples of the ether-based solvent include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, Bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, 1,4-dioxane, etc. In addition, specific examples of the carbonate-based solvent include diethyl carbonate, ethyl methyl carbonate, ethylidene carbonate, propylene carbonate, and the like. Among the above reaction solvents, an aprotic solvent is preferred, an amide-based solvent and a lactone-based solvent are more preferred, and a lactone-based solvent is even more preferred. Moreover, the said reaction solvent may be used individually or in mixture of 2 or more types.

For the imidization reaction, a Dean-Stark apparatus or the like is preferably used, and the reaction is carried out while removing water generated during production. By carrying out such an operation, the degree of polymerization and the imidization rate can be further increased.

A known imidization catalyst can be used for the above imidization reaction. The imidization catalyst includes an alkali catalyst or an acid catalyst. Examples of the base catalyst include: pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine ( TEA), tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, N,N-diethylaniline and other organic base catalysts; potassium hydroxide, or sodium hydroxide, Inorganic base catalysts such as potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate. Moreover, as an acid catalyst, crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, toluic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid can be mentioned. , naphthalene sulfonic acid, etc. The above-mentioned imidization catalysts may be used alone or in combination of two or more. Among the above, from the viewpoint of workability, it is preferable to use an alkali catalyst, more preferably an organic alkali catalyst, and even more preferably triethylamine and triethylenediamine.

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

[Polyimide Varnish] The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin of the present invention and an organic solvent, and the polyimide resin is dissolved in the organic solvent. The organic solvent is not particularly limited as long as it can dissolve the polyimide resin, and the above-mentioned compounds as the reaction solvent used in the production of the polyimide resin are preferably used alone or in combination of two or more. The polyimide varnish of the present invention may be a polyimide solution itself obtained by dissolving a polyimide resin obtained by a polymerization method in a reaction solvent, or a further solvent may be added to the polyimide solution and diluted.

The polyimide resin of the present invention has solvent solubility, so it can be made into a high-concentration varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains the polyimide resin of the present invention in an amount of 5 to 40% by mass, more preferably 5 to 20% by mass. The viscosity of the polyimide varnish is preferably 1~200Pa･s, more preferably 1~100Pa･s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer. In addition, the polyimide varnish of the present invention may also contain inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, interfacial active agents within the range that does not impair the required properties of the polyimide film. agents, leveling agents, defoaming agents, optical brighteners, cross-linking agents, polymerization initiators, sensitizers and other additives. The manufacturing method in particular of the polyimide varnish of this invention is not restrict|limited, A well-known method can be used.

[Polyimide film] The polyimide film of the present invention contains the polyimide resin of the present invention. Therefore, the polyimide film of the present invention is excellent in heat resistance, transparency, toughness, optical isotropy, peelability and chemical resistance. The desirable physical properties of the polyimide film of the present invention are as described in the above-mentioned <Characteristics of Polyimide Resin>. The manufacturing method of the polyimide film of this invention is not specifically limited, A well-known method can be used. For example, the polyimide varnish of the present invention is applied to a smooth support such as a glass plate, metal plate, plastic, etc. in the form of a thin film, or after the polyimide varnish is formed into a thin film, the reaction solvent contained in the varnish, A method of removing organic solvents such as dilution solvents by heating, etc. The manufacturing method of the polyimide film of the present invention is preferably a method including the step of removing the organic solvent after coating or forming the polyimide varnish into a film.

Examples of the coating method include known coating methods such as spin coating, slit coating, and knife coating, and spin coating and slit coating are preferred. Among them, slit coating is preferable from the viewpoint of controlling intermolecular alignment and improving chemical resistance and workability. The method of removing the organic solvent contained in the varnish by heating is preferably at a temperature below 150°C to evaporate the organic solvent to become non-viscous, and then at a temperature above the boiling point of the organic solvent used (preferably 200~500°C, but not particularly limited) to be dried. In addition, drying is preferably carried out in an air atmosphere or a nitrogen atmosphere. The pressure of the dry environment may be any of reduced pressure, normal pressure, and increased pressure. The method of peeling the polyimide film formed on the support from the support is not particularly limited, and a mechanical peeling method, a laser lift-off method, or the like can be used.

In addition, the polyimide film of the present invention can also be produced using a polyamic acid varnish obtained by dissolving polyamic acid in an organic solvent. The polyamic acid contained in the above-mentioned polyamic acid varnish is a precursor of the polyimide resin of the present invention, and comprises the above-mentioned tetracarboxylic acid component of the compound providing the structural unit (A1) and the above-mentioned providing structural unit (B1). ) is the product of the addition polymerization reaction of the diamine component of the compound. The polyimide resin of the present invention can be obtained as the final product by imidizing the polyimide (dehydration ring closure). As the organic solvent contained in the aforementioned polyimide varnish, the organic solvent contained in the polyimide varnish of the present invention can be used. In the production of the polyimide film of the present invention, the polyimide varnish may be a polyimide solution itself obtained by addition-polymerizing a tetracarboxylic acid component and a diamine component in a reaction solvent, or it may be It was obtained by further adding a solvent to the polyamic acid solution and diluting it.

There is no restriction|limiting in particular in the method of manufacturing a polyimide film using a polyimide varnish, and a well-known method can be used. For example, a polyamide varnish can be applied to a smooth support such as a glass plate, metal plate, plastic, etc. in a thin film, or formed into a thin film, and the organic solvent such as a reaction solvent and a dilution solvent contained in the varnish can be used. The polyamic acid film is obtained by removing by heating, and then the polyamic acid in the polyamic acid film is imidized by heating, whereby a polyimide film can be produced. The heating temperature for drying the polyamide varnish to obtain the polyamide film is preferably 50 to 120°C. The heating temperature when the polyamic acid is imidized by heating is preferably 200 to 450°C. In addition, the method of imidization is not limited to thermal imidization, and chemical imidization can also be used.

The thickness of the polyimide film of the present invention can be appropriately selected according to the application, etc., and is preferably 1 to 250 μm, more preferably 5 to 100 μm, more preferably 8 to 80 μm, and even more preferably in the range of 10 to 80 μm. Since 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.

In the polyimide film of the present invention, in accordance with JIS K7127: 1999, the tension measured under the conditions of distance between jigs: 50 mm, test piece size: 10 mm × 70 mm, tensile speed: 20 mm/min, and measurement temperature: 23°C The tensile elongation at break is preferably 9.5% or more, more preferably 10.0% or more, and even more preferably 10.5% or more, from the viewpoint of further suppressing the cracking of the inorganic film when exposed to high temperature in the state where the inorganic film is laminated. The upper limit of the tensile elongation at break is preferably 20.0% or less, more preferably 15.0% or less, and even more preferably 13.5% or less.

In the polyimide film of the present invention, the total light transmittance measured in accordance with JIS K7136:2000 is preferably 80% or more, more preferably 88% or more, from the viewpoint of improving transparency. Even better, 88.5% or more is still better, and 89% or more is still better.

The polyimide film of the present invention can be ideally used as a film for various components such as color filters, flexible displays, semiconductor components, optical components, solar cells, and image display devices, and is particularly useful as a transparent film constituting these devices. Sexual substrates are ideally used. In particular, the polyimide film of the present invention can be preferably used as a transparent substrate constituting image display devices such as liquid crystal displays, OLED displays, and touch panels.

[image display device] The image display device of the present invention includes the polyimide film of the present invention as a transparent substrate. The image display device of the present invention includes, for example, a transparent substrate made of the polyimide film of the present invention, and a display portion provided on the transparent substrate. The display portion is not particularly limited, and examples include those using TFT elements, organic EL elements, color filters, LEDs, transistors, electron emission elements, electronic inks, electrophoretic elements, and GLV (grating light valves). valve), MEMS (micro electro mechanical system, micro electro mechanical system) display components; using DMD (digital micro mirror device, digital micromirror device), DMS (digital micro mirror shutter, digital micro shutter), IMOD (interference modulator) , Interferometric modulator) components, electrowetting (electrowetting) components, piezoelectric ceramic displays, carbon nanotube display components, etc. The image display device of the present invention includes, for example, a liquid crystal display, an OLED display, a touch panel, and the like. In addition to using the polyimide film of the present invention as a transparent substrate, the image display device of the present invention can be manufactured according to known information. In the image display device of the present invention, since the polyimide film of the present invention, which is excellent in heat resistance when an inorganic film is laminated, is used as a transparent substrate, cracks in the inorganic film and coloring of the transparent substrate are unlikely to occur, and the reliability is excellent. . [Example]

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

<Film properties and evaluation> Various physical properties of the thin 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 Corporation.

(2) Tensile strength, tensile modulus of elasticity, and tensile elongation at break The tensile strength, tensile modulus of elasticity, and tensile elongation at break were measured using a tensile testing machine "STROGRAPH VG-1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127:1999. The distance between jigs was set to 50 mm, the size of the test piece was set to 10 mm×70 mm, the test speed (tensile speed) was set to 20 mm/min, and the measurement temperature was set to 23°C.

(3) Glass transition temperature (Tg) Using the thermomechanical analyzer "TMA/SS6100" manufactured by Hitachi High-Tech Science Co., Ltd., in the tensile mode, the sample size is 3mm×20mm, the load is 0.1N, and the heating rate is 10℃/min, and the temperature is high enough to remove the residue. The temperature of the stress removes the residual stress and then cools to room temperature. Then, the measurement of the degree of elongation of the test piece was performed under the same conditions as the above-mentioned treatment for removing residual stress, and the glass transition temperature was obtained by extrapolating the inflection point of the degree of elongation.

(4) Total light transmittance and yellow index (YI) The total light transmittance was measured according to JIS K7136:2000, and the YI was measured according to ASTM E313-05 (D light source, 65°).

(5) 5% weight reduction temperature (Td5%) A differential thermogravimetric simultaneous measuring apparatus "NEXTA STA200RV" manufactured by Hitachi High-Tech Science Co., Ltd. was used. The sample was heated from 40 to 150°C at a heating rate of 10°C/min, held at 150°C for 30 minutes to remove moisture, and then heated to 510°C. The temperature at which the weight was reduced by 5% was defined as the 5% weight reduction temperature in comparison with the weight after holding at 150°C for 30 minutes. The larger the value of the weight reduction temperature, the better the heat resistance.

(6) Thickness retardation (Rth) (evaluation of optical isotropy) The thickness retardation (Rth) was measured using an ellipsometer "M-220" manufactured by JASCO Corporation. The value of the thickness retardation at the measurement wavelength of 590 nm was measured. In addition, Rth is represented by the following formula when the largest in-plane refractive index of the polyimide film is nx, the smallest is ny, the refractive index in the thickness direction is nz, and the thickness of the film is d. Rth={[(nx＋ny)/2]-nz}×d

(7) Evaluation of Heat Resistance of Laminated Film The production steps of an image display device were simulated, a laminated film was produced, and the heat resistance of the laminated film was evaluated. The laminated film was prepared as follows. The polyimide films obtained in the examples and comparative examples were not peeled off from the glass plate, but a SiO ₂ film with a thickness of 300 nm was formed on the polyimide film by sputtering, and ITO (indium tin oxide) with a thickness of 1230 nm was formed thereon. ) film to obtain a laminated film. Then, annealing (heating) at 400° C. for 1 hour was performed on the obtained laminated film. The presence or absence of flaws (cracks, yellowing, etc.) in the laminated film before and after annealing was visually observed, and the heat resistance of the polyimide film (laminated film) laminated with the inorganic film was evaluated by the following criteria. 〇: There are no defects such as cracks and yellowing in the laminated film before and after annealing × (cracks or yellowing): There are defects such as cracks and yellowing in the laminated film before and after annealing. When the heat resistance is excellent.

<Abbreviation of ingredients, etc.> The tetracarboxylic acid component, the diamine component, and the abbreviations thereof used in Examples and Comparative Examples are as follows.

(tetracarboxylic acid component) CpODA: norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (ENEOS Co., Ltd. system; compound represented by formula (a11)) BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride (manufactured by Mitsubishi Chemical Corporation, compound represented by formula (a211s) (s-BPDA)) BPAF: 9,9-bis(3,4-dicarboxyphenyl)perylene anhydride (manufactured by JFE Chemical Co., Ltd.; compound represented by formula (a22))

(diamine component) MPD: 1,3-phenylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.; compound represented by formula (b1)) BAFL: 9,9-bis(4-aminophenyl) fluoride (manufactured by JFE Chemical Co., Ltd.; compound represented by formula (b21)) TFMB: 2,2'-bis(trifluoromethyl)benzidine (manufactured by SEIKA Co., Ltd.; compound represented by formula (b22)) PPD: 1,4-phenylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.)

<Manufacture of polyimide resins, varnishes and polyimide films> Example 1 Put 5.407 g (0.050 mol) in a 500 mL 5-neck round-bottomed flask equipped with a stainless steel half-moon-shaped stirring blade, a nitrogen introduction tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap. MPD, 17.423 g (0.050 mol) of BAFL, and 73.521 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were stirred at 200 rpm at a temperature of 70°C in the system under a nitrogen atmosphere to obtain a solution . To this solution, 38.438 g (0.100 mol) of CpODA and 18.380 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) were added at one time, and then 0.506 g of the third imidization catalyst was added. Ethylamine (manufactured by Kanto Chemical Co., Ltd.) and 0.056 g of triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) were heated with a mantle heater, and the temperature in the reaction system was raised to 190°C. The distilled components were collected, and the rotation speed was adjusted in accordance with the increase in viscosity while maintaining the temperature in the reaction system at 190° C. for 3 hours under reflux. Then, γ-butyrolactone (manufactured by Mitsubishi Chemical Co., Ltd.) was added so as to have a solid content concentration of 15% by mass, and the temperature in the reaction system was cooled to 100° C., followed by stirring for further about 1 hour to homogenize, to obtain Polyimide varnish. Then, the obtained polyimide varnish was coated on a glass plate by spin coating, kept at 80° C. for 20 minutes with a hot plate, and then heated in a hot air dryer at 400° C. for 30 minutes under a nitrogen atmosphere (heating up speed 5°C/min), the solvent was evaporated, and a thin film was obtained.

Example 2 In addition to changing the amount of MPD from 5.407 g (0.050 mol) to 7.570 g (0.070 mol), and changing the amount of BAFL from 17.423 g (0.050 mol) to 10.454 g (0.030 mol), In the same manner as in Example 1, a polyimide varnish having a solid content concentration of 15% by mass was obtained. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Example 3 In addition to changing the amount of MPD from 5.407 g (0.050 mol) to 8.651 g (0.080 mol), and changing the amount of BAFL from 17.423 g (0.050 mol) to 6.969 g (0.020 mol), In the same manner as in Example 1, a polyimide varnish having a solid content concentration of 15% by mass was obtained. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Example 4 The amount of CpODA was changed from 38.438 g (0.100 mol) to 30.750 g (0.080 mol), 5.885 g (0.020 mol) of BPDA was used, and the amount of MPD was changed from 5.407 g (0.050 mol) to 6.488 g ( 0.060 mol), except that the amount of BAFL was changed from 17.423 g (0.050 mol) to 13.938 g (0.040 mol), by the same method as in Example 1, a solid content concentration of 15 mass % was obtained. Polyimide varnish. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Example 5 The amount of CpODA was changed from 38.438 g (0.100 mol) to 34.594 g (0.090 mol), 4.584 g (0.010 mol) of BPAF was used, and the amount of MPD was changed from 5.407 g (0.050 mol) to 6.488 g ( 0.060 mol), except that the amount of BAFL was changed from 17.423 g (0.050 mol) to 13.938 g (0.040 mol), by the same method as in Example 1, a solid content concentration of 15 mass % was obtained. Polyimide varnish. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Comparative Example 1 Except that the amount of BAFL was changed from 17.423 g (0.050 mol) to 34.845 g (0.100 mol) without using MPD, the same method as in Example 1 was used to obtain a polyamide having a solid content concentration of 15% by mass. Imine varnish. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Comparative Example 2 The amount of CpODA was changed from 38.438 g (0.100 mol) to 23.063 g (0.060 mol), 11.769 g (0.040 mol) of BPDA was used, and the amount of BAFL was changed from 17.423 g (0.050 mol) without MPD A polyimide varnish having a solid content concentration of 15 mass % was obtained by the same method as in Example 1, except that 19.214 g (0.060 mol) of TFMB was used as 13.938 g (0.040 mol). Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Comparative Example 3 The amount of CpODA was changed from 38.438 g (0.100 mol) to 34.594 g (0.090 mol), 4.584 g (0.010 mol) of BPAF was used, and the amount of BAFL was changed from 17.423 g (0.050 mol) without MPD A polyimide varnish having a solid content concentration of 15 mass % was obtained by the same method as in Example 1, except that 15.680 g (0.045 mol) and 17.613 g (0.055 mol) of TFMB were used. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Comparative Example 4 Except that MPD7.570g (0.070mol) was changed to PPD7.570g (0.070mol), the synthesis was attempted by the same method as in Example 2, but after adding the imidization catalyst, the temperature was raised to 190 In the process of ℃, solids were precipitated at the same time as the imidization, and the polyimide varnish could not be obtained.

Comparative Example 5 Put 10.814g (0.100mol) into a 300mL 5-neck round-bottomed flask equipped with a stainless steel half-moon-shaped stirring blade, a nitrogen introduction tube, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and a glass end cap. MPD and 182.403 g of NMP were stirred at a rotational speed of 200 rpm at a temperature of 25° C. in the system under a nitrogen atmosphere to obtain a solution. 29.422 g (0.100 mol) of BPDA and 45.601 g of NMP were put into this solution at one time, and the solution was stirred for 3 hours to obtain a polyamide varnish having a solid content concentration of 15.0 mass %. Then, the obtained polyamide varnish was coated on a glass plate by spin coating, kept at 80° C. for 20 minutes with a hot plate, and then heated in a hot air dryer at 430° C. for 60 minutes under a nitrogen atmosphere (heating up speed 5°C/min), the solvent was evaporated, and a thin film was obtained.

Comparative Example 6 A polyimide varnish having a solid content concentration of 15 mass % was obtained by the same method as in Example 1, except that MPD was not used as the diamine, but 16.012 g (0.050 mol) of TFMB was used. Using the obtained polyimide varnish, a film was obtained in the same manner as in Example 1.

Comparative Example 7 The synthesis was attempted in the same manner as in Example 1, except that the amount of MPD was changed from 5.407 g (0.050 mol) to 10.814 g (0.100 mol), and BAFL was not used, except that an imidization catalyst was added. After that, in the process of raising the temperature to 190° C., solids were precipitated at the same time as imidization, and a polyimide varnish could not be obtained.

The aforementioned physical property measurements and evaluations were performed on the polyimide films obtained in the Examples and Comparative Examples. The obtained results are shown in Table 1.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Polyimide resin Tetracarboxylic acid components (numbers indicate molar ratios) CpODA 100 100 100 80 90 100 60 90 100 - 100 100 BPDA - - - 20 - - 40 - - 100 - - BPAF - - - - 10 - - 10 - - - - Diamine composition (numbers indicate molar ratios) MPD 50 70 80 60 60 - - - - 100 - 100 BAFL 50 30 20 40 40 100 40 45 30 - 50 - TFMB - - - - - - 60 55 - - 50 - PPD - - - - - - - - 70 - - - Film evaluation - Film thickness [μm] 9.8 9.8 9.1 10.7 8.9 9.9 10.0 10.0 cannot be synthesized 7.7 9.8 cannot be synthesized Optical properties Total light transmittance [%] 89.3 89.5 88.0 88.2 89.1 89.0 89.0 89.9 66.4 89.8 YI 1.2 1.5 1.7 4.8 2.2 1.2 3.8 1.3 41.5 1.1 Rth 86 125 128 171 87 29 346 205 350 164 Thermal characteristics Tg[℃] 452 430 414 421 424 475 427 453 346 431 Td5%[℃] >510 >510 482 >510 505 >510 495 503 >510 >510 Mechanical properties Tensile strength [MPa] 94 97 98 105 98 99 140 126 140 87 Tensile elastic modulus [GPa] 2.3 2.6 2.6 2.9 2.7 2.6 3.5 3.2 3.5 3.1 Tensile elongation at break[%] 10.5 12.1 12.7 10.8 9.6 7.8 10.0 9.0 9.0 3.9 Heat resistance of laminated film 400℃, 1 hour 〇 〇 〇 〇 〇 × (crack) × (yellow) × (yellow) × (crack) × (yellow)

As shown in Table 1, it can be seen that the polyimide films of Examples are excellent in transparency and heat resistance when an inorganic film is laminated. In addition, it can be seen that the polyimide films of the examples have good optical isotropy. Comparative Examples 1 and 6 were excellent in optical isotropy, but inferior in heat resistance of the laminated film. In Comparative Example 2, the optical isotropy and the heat resistance of the laminated film were poor. In Comparative Example 3, the heat resistance of the laminated film was poor. In Comparative Examples 4 and 7, since the resin after imidization was poor in solubility and precipitated, the subsequent polymerization was not performed, and a polyimide varnish could not be obtained. Comparative Example 5 was inferior in transparency, optical isotropy, and heat resistance of the laminated film. Therefore, a polyimide film produced by using an acid dianhydride having two norbornane skeletons in the molecule as the tetracarboxylic acid component and using MPD as the diamine component can be used as a transparent, optically isotropic and laminated film. The film is excellent in heat resistance and can be ideally used as a transparent substrate constituting display devices such as liquid crystal displays, OLED displays, and touch panels.

Claims (12)

A polyimide resin comprising a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine; the structural unit A includes a structural unit A derived from a tetracarboxylic dianhydride having two norbornane skeletons in the molecule. A structural unit (A1), the structural unit B includes a structural unit (B1) derived from a compound represented by the following formula (b1), and the ratio of the structural unit (B1) in the structural unit B is 35 mol % or more and 95 mol % or more ear% below;

. The polyimide resin according to claim 1, wherein the constituent unit (A1) comprises a constituent unit (A11) selected from a compound represented by the following formula (a11) and a constituent unit derived from a compound represented by the following formula (a12) (A12), at least one of the group consisting of a structural unit (A13) derived from a compound represented by the following formula (a13), and a structural unit (A14) derived from a compound represented by the following formula (a14);

. The polyimide resin of claim 1 or 2, wherein the structural unit A further comprises a structural unit (A2), and the structural unit (A2) comprises a structural unit selected from the group consisting of compounds represented by the following formula (a21) ( A21), and at least one kind from the group consisting of the structural unit (A22) of the compound represented by the following formula (a22);

. The polyimide resin according to any one of claims 1 to 3, wherein the constituent unit B further comprises a constituent unit (B2), and the constituent unit (B2) comprises a compound selected from the group consisting of compounds represented by the following formula (b21) The structural unit (B21) derived from the compound represented by the following formula (b22), the structural unit (B22) derived from the compound represented by the following formula (b23), and the structural unit (B23) derived from the compound represented by the following formula (b24) At least one of the groups formed by the constituent unit (B24);

. The polyimide resin of claim 4, wherein the structural unit (B2) comprises a structural unit (B21) derived from a compound represented by the following formula (b21);

. A polyimide varnish is obtained by dissolving the polyimide resin according to any one of claims 1 to 5 in an organic solvent. A polyimide film comprising the polyimide resin according to any one of claims 1 to 5. The polyimide film of claim 7, which is measured according to JIS K7127:1999 under the conditions of distance between clamps: 50 mm, size of test piece: 10 mm×70 mm, tensile speed: 20 mm/min, and measurement temperature: 23°C The tensile elongation at break is 9.5% or more. The polyimide film of claim 7 or 8, wherein the total light transmittance measured according to JIS K7136:2000 is 80% or more. The polyimide film according to any one of claims 7 to 9 is used as a transparent substrate constituting a display device. A manufacturing method of a polyimide film, comprising the following steps: After the polyimide varnish as claimed in claim 6 is applied or formed into a film, the organic solvent is removed. An image display device comprising the polyimide film according to any one of claims 7 to 10 as a transparent substrate.