Polyimide resin, polyimide resin composition, polyimide varnish and polyimide film

Abstract

The present invention is a polyimide resin, which has: a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A includes: at least one structural unit selected from the group consisting of a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2), and the structural unit B includes: at least one structural unit (B1) selected from the group consisting of a structural unit derived from a compound represented by the following formula (b11), a structural unit derived from a compound represented by the following formula (b12), and a structural unit derived from a compound represented by the following formula (b13); and, at least one structural unit (B2) selected from the group consisting of a structural unit derived from a compound represented by the following general formula (b21) and a structural unit derived from a compound represented by the following general formula (b22), and the molar ratio of the structural unit (B1) to the structural unit (B2) [(B1) / (B2)] is 45 / 55 to 75 / 25. The present invention provides: a polyimide resin, a polyimide resin composition, a polyimide varnish and a polyimide film capable of forming a film having excellent transparency, optical isotropy and ductility. (wherein, R 1 and R 2 Each independently represents a methyl group or a trifluoromethyl group, X 1 ~X 4 Each independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -S-, -SO-, -SO 2 ‑, ‑O‑, or ‑CO‑. )

Description

Technical Field

[0001] The invention relates to a polyimide resin, a polyimide resin composition, a polyimide varnish and a polyimide film. Background Art

[0002] Various uses of polyimide resins are being studied in the fields of electrical and electronic components. For example, in order to make devices lighter and more flexible, it is expected that glass substrates used in image display devices such as liquid crystal displays and OLED displays will be replaced with plastic substrates, and research on polyimide films suitable as such plastic substrates has been promoted. Transparency is required for polyimide films used in such applications.

[0003] Furthermore, as required properties of the polyimide film, a small phase difference due to birefringence and a low retardation (good optical isotropy) are required.

[0004] Patent Document 1 discloses, as a polyimide resin providing a thin film with reduced birefringence, a polyimide resin obtained by using a diamine (eg, metaphenylenediamine) in which at least one of the amino groups of the diamine is bonded to the meta position with respect to the main chain.

[0005] Patent document 2 discloses a polyimide resin as a polyimide resin for providing a film having excellent heat resistance, transmittance, low linear expansion coefficient and low retardation, which comprises a tetracarboxylic acid residue and a diamine residue of a specific structure, and comprises a tetracarboxylic acid residue and / or a diamine residue having a curved portion. Specifically, a polyimide resin is disclosed, which is obtained using 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biscyclohexanetetracarboxylic dianhydride, pyromellitic anhydride, 2,2'-bis(trifluoromethyl)benzidine, and 4,4'-diaminodiphenyl sulfone.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 8-134211

[0009] Patent Document 2: International Publication No. 2015 / 125895 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] As mentioned above, good optical properties such as transparency and optical isotropy are required for polyimide films. On the other hand, polyimide has a rigid and strong molecular structure, so breakage caused by shrinkage during film manufacturing and breakage when used in products with movable parts (such as flexible displays) become problems. In order to suppress breakage and improve ductility, for example, when a component with high flexibility is introduced into the molecule, the optical properties are usually reduced. In this way, a polyimide film with good optical properties and ductility is sought.

[0012] Therefore, an object of the present invention is to provide a polyimide resin, a polyimide resin composition, a polyimide varnish, and a polyimide film which can form a film having excellent transparency, optical isotropy, and ductility.

[0013] Solutions for solving problems

[0014] The present inventors have found that a polyimide resin including a combination of specific structural units and a resin composition including the polyimide resin and a specific polymer can solve the above-mentioned problems, and have thus completed the invention.

[0015] That is, the present invention relates to the following [1] to [8]. [1]

[0017] A polyimide resin comprising: a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine,

[0018] The structural unit A comprises at least one structural unit selected from the group consisting of a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2).

[0019] The structural unit B comprises: at least one structural unit (B1) selected from the group consisting of a structural unit derived from a compound represented by the following formula (b11), a structural unit derived from a compound represented by the following formula (b12), and a structural unit derived from a compound represented by the following formula (b13); and,

[0020] at least one structural unit (B2) selected from the group consisting of a structural unit derived from a compound represented by the following general formula (b21) and a structural unit derived from a compound represented by the following general formula (b22),

[0021] The molar ratio of the structural unit (B1) to the structural unit (B2) [(B1) / (B2)] is 45 / 55 to 75 / 25.

[0022]

[0023] (In formula (b11), R 1and R 2 Each independently represents a methyl group or a trifluoromethyl group. In formulas (b21) and (b22), X 1 ~X 4 Each independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -S-, -SO-, -SO2-, -O- or -CO-.) [2]

[0025] The polyimide resin according to the above [1], wherein the elongation at break measured in accordance with JIS K 7127 is 10% or more. [3]

[0027] The polyimide resin according to any one of [1] or [2] above, wherein the structural unit (B2) comprises: at least one structural unit selected from the group consisting of a structural unit derived from a compound represented by the following formula (b211), a structural unit derived from a compound represented by the following formula (b212), and a structural unit derived from a compound represented by the following formula (b213).

[0028] [4]

[0030] A polyimide resin composition comprising: the polyimide resin according to any one of [1] to [3] above; and at least one selected from the group consisting of a fluorine-containing polymer and a silicone-containing polymer. [5]

[0032] The polyimide resin composition according to the above [4], wherein the total content of the fluorine-containing polymer and the silicone-containing polymer is 0.01 to 2 parts by mass based on 100 parts by mass of the polyimide resin. [6]

[0034] The polyimide resin composition according to the above [4] or [5], wherein the fluorinated polymer is a fluorinated acrylic polymer. [7]

[0036] A polyimide varnish obtained by dissolving the polyimide resin according to any one of [1] to [3] above or the polyimide resin composition according to any one of [4] to [6] above in an organic solvent. [8]

[0038] A polyimide film comprising: the polyimide resin according to any one of [1] to [3] above, or the polyimide resin composition according to any one of [4] to [6] above.

[0039] Effects of the Invention

[0040] According to the present invention, there can be provided a polyimide resin, a polyimide resin composition, a polyimide varnish, and a polyimide film capable of forming a thin film having excellent transparency, optical isotropy, and ductility. DETAILED DESCRIPTION

[0041] [Polyimide resin]

[0042] The polyimide resin of the present invention comprises a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A comprises at least one structural unit selected from the group consisting of a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2), and the structural unit B comprises a structural unit derived from a compound represented by the following formula (b11) (hereinafter, also referred to as a structural unit (B11)), a structural unit derived from a compound represented by the following formula (b12) (hereinafter, also referred to as a structural unit (B12)), and a structural unit derived from a compound represented by the following formula (b13) (hereinafter, also referred to as a structural unit (B13)). At least one structural unit (B1) selected from the group consisting of structural units of compounds represented by the following formula (b13) (hereinafter also referred to as structural units (B13)); and at least one structural unit (B2) selected from the group consisting of structural units derived from compounds represented by the following general formula (b21) (hereinafter also referred to as structural units (B21)) and structural units derived from compounds represented by the following general formula (b22) (hereinafter also referred to as structural units (B22)), wherein the molar ratio of structural units (B1) to structural units (B2) [(B1) / (B2)] is 45 / 55 to 75 / 25.

[0043]

[0044] (In formula (b11), R 1 and R 2 Each independently represents a methyl group or a trifluoromethyl group. In formulas (b21) and (b22), X 1 ~X 4 Each independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -S-, -SO-, -SO2-, -O- or -CO-.)

[0045] <Structural unit A>

[0046] The structural unit A is a structural unit derived from tetracarboxylic dianhydride which accounts for a large proportion in the polyimide resin, and the structural unit A includes at least one structural unit selected from the group consisting of a structural unit (A1) derived from a compound represented by the following formula (a1) and a structural unit (A2) derived from a compound represented by the following formula (a2).

[0047]

[0048] The compound represented by formula (a1) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

[0049] By including the structural unit (A1), the transparency and optical isotropy of the film can be improved, and further, the heat resistance and thermal stability can be improved.

[0050] The compound represented by formula (a2) is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride.

[0051] The structural unit A contains the structural unit (A2), thereby improving the transparency of the film and improving the solubility of the polyimide in the organic solvent.

[0052] The structural unit A may include both the structural unit (A1) and the structural unit (A2), but preferably includes either the structural unit (A1) or the structural unit (A2), and more preferably includes the structural unit (A1).

[0053] When the structural unit A contains the structural unit (A1) and the structural unit (A2), the total ratio of the structural units (A1) and (A2) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total ratio of the structural units (A1) and (A2) is not particularly limited, that is, it is 100 mol%.

[0054] When the structural unit A contains the structural unit (A1), the ratio of the structural unit (A1) in the structural unit A is preferably 45 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, that is, 100 mol%. Similarly, the ratio of the structural unit (A1) in the structural unit A is preferably 45 to 100 mol%, more preferably 70 to 100 mol%, further preferably 90 to 100 mol%, and particularly preferably 99 to 100 mol%.

[0055] When structural unit A includes structural unit (A2), the ratio of structural unit (A2) in structural unit A is preferably 45 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio is not particularly limited, that is, 100 mol%. Similarly, the ratio of structural unit (A2) in structural unit A is preferably 45 to 100 mol%, more preferably 70 to 100 mol%, further preferably 90 to 100 mol%, and particularly preferably 99 to 100 mol%.

[0056] The structural unit A may further include a structural unit (A3) derived from a compound represented by the following formula (a3).

[0057]

[0058] The compound represented by formula (a3) ​​is norbornane-2-spiro-α-cyclopentanone-α′-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydride. When structural unit A contains structural unit (A3), the transparency of the film is improved.

[0059] When the structural unit A contains the structural unit (A3), the ratio of the structural unit (A3) in the structural unit A is preferably 55 mol% or less, more preferably 30 mol% or less, and preferably 5 mol% or more.

[0060] When the structural unit A includes the structural unit (A3), the structural unit A preferably includes the structural unit (A1) and the structural unit (A3), and more preferably consists of the structural unit (A1) and the structural unit (A3).

[0061] The structural unit A may also contain structural units other than the structural units (A1) to (A3) within a range that does not impair the effects of the present invention. The tetracarboxylic dianhydride that provides such a structural unit is not particularly limited, and examples thereof include aromatic dianhydrides such as pyromellitic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, and 2,2',3,3'-biphenyl tetracarboxylic dianhydride. Aromatic tetracarboxylic dianhydrides (excluding compounds represented by formula (a2)); alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, and dicyclohexyltetracarboxylic dianhydride (excluding compounds represented by formula (a1) and compounds represented by formula (a3)); and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride.

[0062] It should be noted that, in the present specification, aromatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing one or more alicyclic rings and no aromatic ring, and aliphatic tetracarboxylic dianhydride refers to a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring.

[0063] The structural unit other than the structural units (A1) to (A3) optionally contained in the structural unit A may be one kind or two or more kinds.

[0064] The structural unit A preferably does not contain any structural unit other than the structural units (A1) to (A3).

[0065] <Structural unit B>

[0066] The structural unit B is a structural unit derived from diamine that accounts for the polyimide resin, and includes: at least one structural unit (B1) selected from the group consisting of a structural unit (B11) derived from a compound represented by the following formula (b11), a structural unit (B12) derived from a compound represented by the following formula (b12), and a structural unit (B13) derived from a compound represented by the following formula (b13); and, at least one structural unit (B2) selected from the group consisting of a structural unit (B21) derived from a compound represented by the following general formula (b21) and a structural unit (B22) derived from a compound represented by the following general formula (b22),

[0067] The molar ratio of the structural unit (B1) to the structural unit (B2) [(B1) / (B2)] is 45 / 55 to 75 / 25.

[0068]

[0069] In formula (b11), R 1 and R 2 Each independently represents a methyl group or a trifluoromethyl group. In formulas (b21) and (b22), X 1 ~X 4 Each independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -S-, -SO-, -SO2-, -O- or -CO-.

[0070] (Structural unit (B1))

[0071] The structural unit (B1) is at least one structural unit selected from the group consisting of a structural unit (B11) derived from a compound represented by the following formula (b11), a structural unit (B12) derived from a compound represented by the following formula (b12), and a structural unit (B13) derived from a compound represented by the following formula (b13).

[0072]

[0073] The compound represented by formula (b11) is 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane or 2,2-bis[4-(4-aminophenoxy)phenyl]propane,

[0074] The compound represented by formula (b12) is 4,4'-diaminodiphenyl ether,

[0075] The compound represented by formula (b13) is 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene.

[0076] Structural unit B contains at least one structural unit selected from the group consisting of structural units (B11) to (B13). Among these, from the viewpoint of improving the ductility of the film, structural unit B more preferably contains at least one structural unit selected from the group consisting of structural units (B11) and structural units (B12), and structural unit B further preferably contains structural unit (B11).

[0077] Structural unit B may contain two or more of structural units (B11) to (B13), but preferably contains one of structural units (B11) to (B13). That is, structural unit B preferably contains structural unit (B11), structural unit (B12), or structural unit (B13).

[0078] By including the structural unit (B1), the structural unit B can maintain the transparency and optical isotropy of the film and improve the ductility. In addition, the colorlessness can also be improved. The structural unit (B1) can be one or more than two. As the structural unit (B1), it is preferably a structural unit derived from 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

[0079] (Structural unit (B2))

[0080] The structural unit (B2) is at least one structural unit selected from the group consisting of a structural unit (B21) derived from a compound represented by the following general formula (b21) and a structural unit (B22) derived from a compound represented by the following general formula (b22).

[0081]

[0082] In formulas (b21) and (b22), X 1 ~X 4 Each independently represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -S-, -SO-, -SO2-, -O- or -CO-.

[0083] The compound represented by the general formula (b21) has 1 and X 2 Connect 3 benzene rings, and X 1 and X 2 The compound represented by the general formula (b22) has a skeleton bonded to the 1 and 3 positions of the central benzene ring and has 3 and X 4 Connect 3 benzene rings, and X 3 and X 4 The skeleton is bonded to the 1 and 2 positions of the central benzene ring. With such a structure, a thin film having ductility, transparency and excellent optical isotropy can be formed.

[0084] From the viewpoint of forming a film having excellent optical isotropy, X in the general formulae (b21) and (b22) 1 ~X 4 Each independently preferably represents an alkylidene group having 3 to 5 carbon atoms, -SO2-, or -O-, more preferably represents an alkylidene group having 3 to 5 carbon atoms, or -O-, further preferably represents an isopropylidene group, or -O-, and further preferably represents an isopropylidene group.

[0085] X in the general formula (b21) 1 and X 2 They may have different groups, but are preferably the same groups. Similarly, X in formula (b22) 3 and X 4 They may have different groups respectively, but are preferably the same groups.

[0086] The amino groups in the general formulae (b21) and (b22) are preferably: 1 ~X 4 Any of , is bonded to the para position or meta position of the benzene ring, and is more preferably bonded to the para position of the benzene ring.

[0087] As X in the general formulae (b21) and (b22) 1 ~X 4 Examples of the alkylidene group having 2 to 5 carbon atoms include ethylidene, propylidene, isopropylidene, butylidene, isobutylidene, pentylidene, isopentylidene, etc. The alkylidene group is preferably an alkylidene group having 3 to 5 carbon atoms, and more preferably isopropylidene.

[0088] The structural unit (B2) preferably includes a structural unit derived from a compound represented by the above-mentioned general formula (b21), and more preferably includes at least one structural unit selected from the group consisting of a structural unit derived from a compound represented by the following formula (b211), a structural unit derived from a compound represented by the following formula (b212), and a structural unit derived from a compound represented by the following formula (b213).

[0089]

[0090] The compound represented by formula (b211) is 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene,

[0091] The compound represented by formula (b212) is 1,3-bis(4-aminophenoxy)benzene,

[0092] The compound represented by formula (b213) is 1,3-bis(3-aminophenoxy)benzene.

[0093] Among the compounds represented by formula (b211) to formula (b213), at least one compound selected from the group consisting of the compound represented by formula (b211) and the compound represented by formula (b212) is preferred, and the compound represented by formula (b211) is more preferred.

[0094] (Other structural units optionally included in structural unit B)

[0095] The structural unit B may contain structural units other than the structural units (B1) and (B2). The diamines that provide such structural units are not particularly limited, and examples thereof include 1,4-phenylenediamine, p-phenylenediamine, 3,5-diaminobenzoic acid, 1,5-diaminonaphthalene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, 3,4'-diaminodiphenyl ether, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5-ol Aromatic diamines such as -amine, N,N'-bis(4-aminophenyl)terephthalamide, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane and 9,9-bis(4-aminophenyl)fluorene, 1,4-bis(4-aminophenoxy)benzene (excluding compounds represented by formulas (b11) to (b13) and compounds represented by formulas (b21) to (b22)); alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine.

[0096] In this specification, aromatic diamine refers to a diamine containing one or more aromatic rings, alicyclic diamine refers to a diamine containing one or more alicyclic rings and no aromatic ring, and aliphatic diamine refers to a diamine containing neither an aromatic ring nor an alicyclic ring.

[0097] The structural units other than the structural units (B1) and (B2) optionally contained in the structural unit B may be one type or two or more types.

[0098] (Composition of structural unit B)

[0099] The structural unit B comprises a structural unit (B1) and a structural unit (B2), and the molar ratio of the structural unit (B1) to the structural unit (B2) is 45 / 55 to 75 / 25. A suitable configuration is described below.

[0100] The total ratio of the structural unit (B1) and the structural unit (B2) in the structural unit B is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and further preferably 95 mol% or more. The upper limit of the total ratio of the structural unit (B1) and the structural unit (B2) is not particularly limited, but is preferably 100 mol%. The structural unit B is further preferably composed of only the structural unit (B1) and the structural unit (B2).

[0101] From the viewpoint of improving transparency, optical isotropy and ductility, the molar ratio of structural unit (B1) to structural unit (B2) [(B1) / (B2)] is 45 / 55 to 75 / 25, and from the viewpoint of transparency, optical isotropy and colorlessness, it is preferably 45 / 55 to 70 / 30, more preferably 45 / 55 to 65 / 35, further preferably 45 / 55 to 60 / 40, and further preferably 45 / 55 to 55 / 45. From the viewpoint of improving ductility, it is preferably 45 / 55 to 75 / 25, more preferably 50 / 50 to 75 / 25, further preferably 55 / 45 to 75 / 25, further preferably 60 / 40 to 75 / 25, and further preferably 65 / 35 to 75 / 25.

[0102] The structural unit B preferably comprises a structural unit (B11) derived from a compound represented by formula (b11) as the structural unit (B1) and a structural unit (B2) derived from a compound represented by formula (b211). The polyimide resin of the present invention preferably comprises a structural unit (A1) derived from a compound represented by formula (a1) as the structural unit A and a structural unit having the above combination as the structural unit B.

[0103] (Physical properties of polyimide resin, etc.)

[0104] From the viewpoint of mechanical strength of the obtained polyimide film, the number average molecular weight of the polyimide resin of the present invention is preferably 5000 to 100000. The number average molecular weight of the polyimide resin can be determined, for example, from a standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration chromatography.

[0105] The polyimide resin of the present invention may contain structures other than the polyimide chain (structure formed by imide bonding of structural unit A and structural unit B). Examples of structures other than the polyimide chain that may be contained in the polyimide resin include structures containing amide bonds.

[0106] The polyimide resin of the present invention preferably contains a polyimide chain (a structure formed by imide bonding of structural unit A and structural unit B) as a main structure. Therefore, the ratio of the polyimide chain of the present invention in the polyimide resin is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and particularly preferably 99% by mass or more.

[0107] By using the polyimide resin of the present invention, a film having excellent transparency, optical isotropy and ductility can be formed, and suitable physical property values ​​of the film are as follows.

[0108] When the film has a thickness of 30 μm, the total light transmittance is preferably 85% or more, more preferably 87% or more, further preferably 88% or more, and further preferably 89% or more.

[0109] When used as a film having a thickness of 30 μm, the yellowness index (YI) is preferably 6.5 or less, more preferably 4.0 or less, further preferably 3.0 or less, further preferably 2.0 or less, further preferably 1.5 or less.

[0110] When the film is formed into a film having a thickness of 30 μm, the haze is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.1% or less.

[0111] In the case of a 30 μm-thick film, the thickness retardation (Rth) is preferably 40 nm or less, more preferably 30 nm or less, further preferably 20 nm or less, and further preferably 18 nm or less.

[0112] The polyimide resin of the present invention has an elongation at break measured in accordance with JIS K 7127 of preferably 10% or more, more preferably 18% or more, further preferably 20% or more, and further preferably 30% or more.

[0113] It should be noted that the above-mentioned physical property values ​​in the present invention can be specifically measured by the methods described in the Examples.

[0114] [Method for producing polyimide resin]

[0115] The polyimide resin of the present invention can be produced by reacting a tetracarboxylic acid component containing at least one selected from the group consisting of a compound providing the structural unit (A1) and a compound providing the structural unit (A2), and a diamine component containing a compound providing the structural unit (B1) and a compound providing the structural unit (B2).

[0116] As the compound providing the structural unit (A1), the compound shown in formula (a1) can be cited, but it is not limited thereto, and its derivative can also be provided within the scope of providing the same structural unit. As the derivative, tetracarboxylic acid corresponding to the tetracarboxylic dianhydride shown in formula (a1) and the alkyl ester of the tetracarboxylic acid can be cited. As the compound providing the structural unit (A1), the compound shown in formula (a1) (i.e., dianhydride) is preferred.

[0117] Similarly, as the compound providing structural unit (A2), the compound shown in formula (a2) can be cited, but it is not limited thereto, and it can also be its derivative within the scope of providing the same structural unit. As the derivative, tetracarboxylic acid corresponding to the tetracarboxylic dianhydride shown in formula (a2) and the alkyl ester of the tetracarboxylic acid can be cited. As the compound providing structural unit (A2), the compound shown in formula (a2) (i.e., dianhydride) is preferred.

[0118] The tetracarboxylic acid component preferably contains 50 mol% or more, more preferably 70 mol% or more, further preferably 90 mol% or more, and particularly preferably 99 mol% or more of the compound providing the structural unit (A1) and the compound providing the structural unit (A2). The upper limit of the total content of the compound providing the structural unit (A1) and the compound providing the structural unit (A2) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may also be composed only of the compound providing the structural unit (A1) and the compound providing the structural unit (A2).

[0119] When the tetracarboxylic acid component includes a compound providing a structural unit (A1) or a compound providing a structural unit (A2), it is preferably 45 mol% or more, more preferably 70 mol% or more, and further preferably 90 mol% or more of the compound providing a structural unit (A1) or the compound providing a structural unit (A2). The upper limit of the content of the compound providing a structural unit (A1) or the compound providing a structural unit (A2) is not limited, that is, 100 mol%. The tetracarboxylic acid component may be composed only of a compound providing a structural unit (A1) or a compound providing a structural unit (A2), and is preferably composed only of a compound providing a structural unit (A1).

[0120] The tetracarboxylic acid component may contain a compound providing the above structural unit (A3) within a range not impairing the optical isotropy and ductility.

[0121] As the compound providing the structural unit (A3), the compound shown in formula (a3) ​​can be cited, but it is not limited thereto, and its derivative can also be provided within the scope of providing the same structural unit. As the derivative, tetracarboxylic acid corresponding to the tetracarboxylic dianhydride shown in formula (a3) ​​and the alkyl ester of the tetracarboxylic acid can be cited. As the compound providing the structural unit (A3), the compound shown in formula (a3) ​​(i.e., dianhydride) is preferred.

[0122] When the tetracarboxylic acid component contains a compound providing structural unit (A3), it is preferably 55 mol% or less, more preferably 30 mol% or less of the compound providing structural unit (A3). In addition, it is preferably 5 mol% or more. When the tetracarboxylic acid component contains a compound providing structural unit (A3), it is preferably composed only of a compound providing structural unit (A1) and a compound providing structural unit (A3).

[0123] The tetracarboxylic acid component may contain compounds other than the compound providing the structural unit (A1), the compound providing the structural unit (A2), and the compound providing the structural unit (A3), and examples of such compounds include the above-mentioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic tetracarboxylic dianhydride, and derivatives thereof (tetracarboxylic acids, alkyl esters of tetracarboxylic acids, etc.).

[0124] The compound other than the compound which provides structural units (A1)-(A3) which is arbitrarily contained in the tetracarboxylic acid component may be 1 type or 2 or more types.

[0125] As the compound providing the structural unit (B1), the compound providing the structural unit (B11), i.e., the compound shown in the general formula (b11), the compound providing the structural unit (B12), i.e., the compound shown in the general formula (b12), and the compound providing the structural unit (B13), i.e., the compound shown in the general formula (b13), can be cited, but it is not limited thereto, and its derivatives can also be provided within the scope of providing the same structural unit. As the derivative, diisocyanates corresponding to the compound shown in the general formula (b11), the compound shown in the general formula (b12), and the compound shown in the general formula (b13) can be cited. As the compound providing the structural unit (B1), it is preferred to select at least one compound (i.e., diamine) from the group consisting of the compound shown in the general formula (b11), the compound shown in the general formula (b12), and the compound shown in the general formula (b13).

[0126] The diamine component may contain a compound that provides two or more of the structural units (B11) to (B13), and preferably contains a compound that provides one of the structural units (B11) to (B13). That is, the structural unit B preferably contains a compound that provides the structural unit (B11), a compound that provides the structural unit (B12), or a compound that provides the structural unit (B13).

[0127] As the compound providing the structural unit (B2), the compound shown in the general formula (b21) and the compound shown in the general formula (b22) can be cited, but it is not limited thereto, and its derivatives can also be provided within the scope of providing the same structural unit. As the derivative, diisocyanates corresponding to the compound shown in the general formula (b21) and the compound shown in the general formula (b22) can be cited. As the compound providing the structural unit (B2), at least one compound (i.e., diamine) in the group consisting of the compound shown in the general formula (b21) and the compound shown in the general formula (b22) is preferably selected.

[0128] As a compound providing structural unit (B2), it is preferred to include a compound represented by general formula (b21), more preferably include at least one compound selected from the group consisting of a compound represented by formula (b211), a compound represented by formula (b212), and a compound represented by formula (b213), further preferably include at least one compound selected from the group consisting of a compound represented by formula (b211) and a compound represented by formula (b212), and particularly preferably include a compound represented by formula (b211).

[0129] The total amount of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) in the structural unit B is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and further preferably 95 mol% or more. The upper limit of the total content of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) is not particularly limited, but is preferably 100 mol%. It is further preferred that the diamine component consists only of the compound providing the structural unit (B1) and the compound providing the structural unit (B2).

[0130] From the viewpoint of improving transparency, optical isotropy and ductility, the molar ratio of the content of the compound providing the structural unit (B1) to the compound providing the structural unit (B2) [(B1) / (B2)] is preferably 45 / 55 to 75 / 25, and from the viewpoint of transparency, optical isotropy and colorlessness, it is preferably 45 / 55 to 70 / 30, more preferably 45 / 55 to 65 / 35, further preferably 45 / 55 to 60 / 40, and further preferably 45 / 55 to 55 / 45. In addition, from the viewpoint of improving ductility, it is preferably 45 / 55 to 75 / 25, more preferably 50 / 50 to 75 / 25, further preferably 55 / 45 to 75 / 25, further preferably 60 / 40 to 75 / 25, and further preferably 65 / 35 to 75 / 25.

[0131] The diamine component may contain compounds other than the compound providing the structural unit (B1) and the compound providing the structural unit (B2), and examples of such compounds include the above-mentioned aromatic diamines, alicyclic diamines, and aliphatic diamines, and derivatives thereof (such as diisocyanates).

[0132] The compound other than the compound providing the structural unit (B1) and the compound providing the structural unit (B2) which is optionally contained in the diamine component may be one kind or two or more kinds.

[0133] In the present invention, the charging amount ratio of the tetracarboxylic acid component and the diamine component used for producing the polyimide resin is preferably 0.9 to 1.1 mol of the diamine component relative to 1 mol of the tetracarboxylic acid component.

[0134] In addition, in the present invention, when manufacturing the polyimide resin, in addition to the aforementioned tetracarboxylic acid component and diamine component, an end-capping agent can also be used. As the end-capping agent, monoamines or dicarboxylic acids are preferred. The amount of the end-capping agent introduced is preferably 0.0001 to 0.1 moles, particularly preferably 0.001 to 0.06 moles, relative to 1 mole of the tetracarboxylic acid component. As monoamine end-capping agents, for example, methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. are recommended. Among them, benzylamine and aniline can be suitably used. As dicarboxylic acid end-capping agents, dicarboxylic acids are preferred, and a part of them can be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. are recommended. Among them, phthalic acid and phthalic anhydride can be preferably used.

[0135] There is no restriction|limiting in particular about the method for making the said tetracarboxylic acid component and a diamine component react, A well-known method can be used.

[0136] As specific reaction methods, the following methods can be cited: method (1), a tetracarboxylic acid component, a diamine component and a reaction solvent are added to a reactor, stirred at 0 to 80° C. for 0.5 to 30 hours, and then the temperature is increased to carry out an imidization reaction; method (2), a diamine component and a reaction solvent are added to a reactor and dissolved, and then a tetracarboxylic acid component is added, stirred at 0 to 80° C. for 0.5 to 30 hours as needed, and then the temperature is increased to carry out an imidization reaction; method (3), a tetracarboxylic acid component, a diamine component and a reaction solvent are added to a reactor, and the temperature is immediately increased to carry out an imidization reaction; etc.

[0137] The reaction solvent used in the production of the polyimide resin may be any solvent that does not inhibit the imidization reaction and can dissolve the generated polyimide, and examples thereof include aprotic solvents, phenolic solvents, etheric solvents, and carbonate-based solvents.

[0138] Specific examples of aprotic solvents include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 1,3-dimethylimidazolidinone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphinetriamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and cyclopentane; ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methylcyclohexanone; amine solvents such as picoline and pyridine; and ester solvents such as (2-methoxy-1-methylethyl)acetate.

[0139] 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, and 3,5-xylenol.

[0140] Specific examples of the ether solvent include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, and 1,4-dioxane.

[0141] Specific examples of the carbonate-based solvent include diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, and propylene carbonate.

[0142] Among the above reaction solvents, amide solvents or lactone solvents are preferred. The above reaction solvents may be used alone or in combination of two or more.

[0143] In the imidization reaction, it is preferred to use a Dean-Stark water trap apparatus or the like to carry out the reaction while removing water generated during the production. By carrying out such an operation, the degree of polymerization and the imidization ratio can be further increased.

[0144] In the above-mentioned imidization reaction, a known imidization catalyst can be used. Examples of the imidization catalyst include a base catalyst and an acid catalyst.

[0145] Examples of the base catalyst include organic base catalysts such as pyridine, quinoline, isoquinoline, α-methylpyridine, β-methylpyridine, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, and N,N-diethylaniline; and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogen carbonate, and sodium hydrogen carbonate.

[0146] Examples of the acid catalyst include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. The imidization catalysts described above may be used alone or in combination of two or more.

[0147] Among the above, from the viewpoint of operability, it is preferred to use a base catalyst, more preferably an organic base catalyst, further preferably one or more selected from triethylamine and triethylenediamine, and particularly preferably triethylamine or a combination of triethylamine and triethylenediamine.

[0148] From the viewpoint of reaction rate and suppression of gelation, the temperature of the imidization reaction is preferably 120 to 250° C., more preferably 160 to 200° C. The reaction time is preferably 0.5 to 10 hours after the distillation of generated water starts.

[0149] [Polyimide resin composition]

[0150] The polyimide resin composition of the present invention comprises the polyimide resin of the present invention and at least one selected from the group consisting of a fluorine-containing polymer and an organosilicon-containing polymer. By comprising at least one selected from the group consisting of a fluorine-containing polymer and an organosilicon-containing polymer, high transparency and optical isotropy can be maintained, and ductility can be significantly improved. Of the fluorine-containing polymer and the organosilicon-containing polymer, the fluorine-containing polymer is preferred.

[0151] <Fluoropolymer>

[0152] The fluorine-containing polymer in the polyimide resin composition of the present invention is preferably a polymer having a structural unit derived from a monomer containing fluorine, and more preferably a polymer having a structural unit derived from a monomer containing a fluorinated alkyl group.

[0153] The fluorine-containing polymer in the present invention is preferably a fluorine-containing acrylic polymer.

[0154] The fluorine-containing acrylic polymer preferably contains a structural unit derived from a fluorine-containing acrylic monomer, and more preferably contains a structural unit derived from a fluorine-containing acrylic monomer and a structural unit derived from an acrylic monomer having a hydrophilic group.

[0155] As the fluorine-containing acrylic monomer, a monomer having a perfluoroalkyl group is preferred.

[0156] Examples of the acrylic monomer having a hydrophilic group include acrylic acid, methacrylic acid, hydroxyalkyl (meth)acrylate, polyalkylene glycol (meth)acrylate, acrylamide, and methacrylamide.

[0157] The fluorine-containing acrylic polymer may contain an acrylic monomer having a hydrophobic group. Examples of the acrylic monomer having a hydrophobic group include alkyl (meth)acrylates, silicone-containing (meth)acrylates, and aryl (meth)acrylates.

[0158] Here, "(meth)acrylate" means "acrylate or methacrylate".

[0159] The fluorine-containing acrylic monomer may be copolymerized with other monomers having a vinyl group.

[0160] Examples of commercially available fluorinated polymers include "LE-605", "LE-607", "LE-605DM", and "LE-607DM" manufactured by Kyoeisha Chemical Co., Ltd.

[0161] <Containing silicone polymer>

[0162] Examples of the silicone-containing polymer in the polyimide resin composition of the present invention include modified silicones having various organic modification groups introduced as side chains or various organic modification groups at the ends of the main chain of the silicone skeleton, and silicone-containing acrylic polymers having silicone side chains introduced into the main chain of an acrylic polymer, and silicone-containing acrylic polymers are preferred.

[0163] Examples of the modified silicone include polyether-modified silicones having a polyether group introduced into a side chain or a terminal, and polyester-modified silicones having a polyester group introduced into a side chain or a terminal. Polyether-modified silicones are preferred.

[0164] Examples of the polyether group of the polyether-modified silicone include a polyethylene glycol group and a polypropylene glycol group, and a polyethylene glycol group is preferred.

[0165] As the main chain of the silicone skeleton of the modified silicone, polydimethylsiloxane is preferred.

[0166] The silicone-containing acrylic polymer preferably contains a structural unit derived from an acrylic monomer containing silicone, and more preferably contains a structural unit derived from an acrylic monomer containing silicone and a structural unit derived from an acrylic monomer having a hydrophilic group.

[0167] As the acrylic monomer containing silicone, a monomer having a polydimethylsiloxane group is preferred.

[0168] Examples of the acrylic monomer having a hydrophilic group include acrylic acid, methacrylic acid, hydroxyalkyl (meth)acrylate, polyalkylene glycol (meth)acrylate, acrylamide, and methacrylamide.

[0169] The silicone-containing acrylic polymer may contain an acrylic monomer having a hydrophobic group. Examples of the acrylic monomer having a hydrophobic group include alkyl (meth)acrylates, silicone-containing (meth)acrylates, and aryl (meth)acrylates.

[0170] Here, "(meth)acrylate" means "acrylate or methacrylate".

[0171] The acrylic monomer containing silicone can be copolymerized with other monomers having a vinyl group.

[0172] Examples of commercially available silicone-containing polymers include "LE-302", "LE-304", and "KL-700" manufactured by Kyoeisha Chemical Co., Ltd. and "BYK-378" manufactured by BYK Japan Co., Ltd.

[0173] In the polyimide resin composition of the present invention, the total content of the fluorine-containing polymer and the silicone-containing polymer is preferably 0.01 to 2 parts by mass, more preferably 0.1 to 1.5 parts by mass, further preferably 0.2 to 1.2 parts by mass, and further preferably 0.5 to 1.0 parts by mass relative to 100 parts by mass of the polyimide resin. It should be noted that when only the fluorine-containing polymer is included, the above total content is the content of the fluorine-containing polymer, and when only the silicone-containing polymer is included, the above total content is the content of the silicone-containing polymer.

[0174] [Polyimide varnish]

[0175] The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention or the polyimide resin composition 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 or the polyimide resin composition of the present invention, and an organic solvent, and the polyimide resin or the polyimide resin composition is dissolved in the organic solvent.

[0176] The organic solvent is not particularly limited as long as it dissolves the fluorine-containing polymer and the silicone-containing polymer contained in the polyimide resin and the polyimide resin composition, and the above-mentioned compounds as reaction solvents used in the production of the polyimide resin are preferably used alone or in combination of two or more.

[0177] 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 may be a polyimide solution obtained by further adding a diluting solvent to the polyimide solution. In addition, the fluorine-containing polymer, the silicone-containing polymer, or a mixture thereof may be dissolved in the polyimide solution obtained by dissolving a polyimide resin obtained by a polymerization method in a reaction solvent, or a diluting solvent may be further added.

[0178] The polyimide varnish of the present invention may be obtained by dissolving the polyimide resin of the present invention in a low boiling point solvent having a boiling point of 130° C. or less. By using the low boiling point solvent as an organic solvent, the heating temperature during the manufacture of the polyimide film described later can be reduced. Examples of the low boiling point solvent include carbon tetrachloride, dichloromethane, chloroform, 1,2-dichloroethane, tetrahydrofuran, acetone, and the like, among which dichloromethane is preferred.

[0179] The polyimide resin of the present invention has solvent solubility, and therefore, a high-concentration varnish that is stable at room temperature can be formed. The polyimide varnish of the present invention preferably contains 5 to 40% by mass, and more preferably contains 10 to 30% by mass of the polyimide resin of the present invention. The viscosity of the polyimide varnish is preferably 1 to 200 Pa·s, and 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.

[0180] In addition, the polyimide varnish of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoaming agents, fluorescent brighteners, crosslinking agents, polymerization initiators, and photosensitizers within the range that the required properties of the polyimide film are not impaired.

[0181] The method for producing the polyimide varnish of the present invention is not particularly limited, and a known method can be applied.

[0182] [Polyimide film]

[0183] The polyimide film of the present invention comprises the polyimide resin of the present invention or the polyimide resin composition of the present invention. Therefore, the polyimide film of the present invention has excellent transparency and optical isotropy, and further excellent ductility. The suitable physical property values ​​of the polyimide film of the present invention are as described above.

[0184] There is no particular limitation on the method for producing the polyimide film of the present invention, and a known method can be used. For example, the polyimide varnish of the present invention is coated on a smooth support such as a glass plate, a metal plate, or a plastic, or formed into a film, and then heated to remove organic solvents such as a reaction solvent and a dilution solvent contained in the varnish. A release agent can be pre-coated on the surface of the support as needed.

[0185] As a method for removing the organic solvent contained in the varnish by heating, the following method is preferred. That is, after the organic solvent is evaporated at a temperature of preferably 120°C or less to form a self-supporting film, the self-supporting film is peeled off from the support, the end of the self-supporting film is fixed, and dried at a temperature above the boiling point of the organic solvent used to manufacture a polyimide film. In addition, it is preferred to dry under a nitrogen atmosphere. The pressure of the drying atmosphere can be reduced pressure, normal pressure, or pressurized. The heating temperature when the self-supporting film is dried to manufacture the polyimide film is not particularly limited, and is preferably 200 to 400°C.

[0186] When the organic solvent contained in the polyimide varnish of the present invention is a low boiling point solvent having a boiling point of 130° C. or less, the heating temperature of the self-supporting film is preferably 100 to 180° C. Furthermore, the polyimide film obtained by removing the low boiling point solvent is preferably subjected to an annealing treatment by further heating at a temperature above the glass transition temperature.

[0187] The polyimide film of the present invention can also be produced using a polyamic acid varnish obtained by dissolving a polyamic acid in an organic solvent.

[0188] The polyamic acid contained in the polyamic acid varnish is a precursor of the polyimide resin of the present invention, and is a product of a polyaddition reaction of a tetracarboxylic acid component comprising at least one selected from the group consisting of a compound providing the structural unit (A1) and a compound providing the structural unit (A2), and a diamine component comprising a compound providing the structural unit (B1) and a compound providing the structural unit (B2). The polyamic acid is imidized (dehydrated and ring-closed), thereby obtaining the polyimide resin of the present invention as a final product.

[0189] As the organic solvent contained in the polyamic acid varnish, the organic solvent contained in the polyimide varnish of the present invention can be used.

[0190] In the present invention, the polyamic acid varnish may be a polyamic acid solution itself obtained by subjecting a tetracarboxylic acid component comprising at least one selected from the group consisting of a compound providing the structural unit (A1) and a compound providing the structural unit (A2) and a diamine component comprising a compound providing the structural unit (B1) and a compound providing the structural unit (B2) in a reaction solvent for addition polymerization, or may be a polyamic acid solution obtained by further adding a diluting solvent.

[0191] The method for making polyimide film using polyamic acid varnish is not particularly limited, and known methods can be used. For example, polyamic acid varnish is coated on a smooth support such as a glass plate, a metal plate, plastics, or is formed into a film, and organic solvents such as a reaction solvent and a diluting solvent contained in the varnish are removed by heating to obtain a polyamic acid film, and the polyamic acid in the polyamic acid film is imidized by heating, thereby making a polyimide film.

[0192] The heating temperature when the polyamic acid varnish is dried to obtain a polyamic acid film is preferably 50 to 120° C. The heating temperature when the polyamic acid is imidized by heating is preferably 200 to 400° C.

[0193] It should be noted that the imidization method is not limited to thermal imidization, and chemical imidization may also be applied.

[0194] The thickness of the polyimide film of the present invention can be appropriately selected depending on the application, and is preferably in the range of 1 to 250 μm, more preferably 5 to 100 μm, and even more preferably 10 to 80 μm. When the thickness is in the above range, it can be practically used as a self-supporting film.

[0195] The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish.

[0196] The polyimide film of the present invention is suitable for use as a film for various components such as color filters, flexible displays, semiconductor components, optical components, etc. The polyimide film of the present invention is particularly suitable for use as a substrate for image display devices such as liquid crystal displays and OLED displays.

[0197] Example

[0198] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0199] The solid content concentration of the varnishes obtained in Examples and Comparative Examples and various physical properties of the thin films were measured by the methods shown below.

[0200] (1) Solid content concentration

[0201] The solid content concentration of the varnish was measured by heating a sample at 280° C. for 120 minutes in a small electric furnace “MMF-1” manufactured by AS ONE Corporation and calculating the solid content concentration from the difference in mass of the sample before and after heating.

[0202] (2) Film thickness

[0203] The film thickness was measured using a micrometer manufactured by Mitutoyo Co., Ltd.

[0204] (3) Total light transmittance, haze (evaluation of transparency) and yellowness index (YI)

[0205] The total light transmittance, haze, and YI were measured using a color / turbidity simultaneous measuring device "COH7700" manufactured by Nippon Denshoku Industries Co., Ltd. The total light transmittance and YI were measured in accordance with JIS K7361-1:1997, and the haze was measured in accordance with JIS K7136:2000.

[0206] (4) Thickness phase difference (Rth) (Evaluation of optical isotropy)

[0207] The thickness phase difference (Rth) is measured using an ellipsometer "M-220" manufactured by JASCO Corporation. The value of the thickness phase difference at a measurement wavelength of 550nm is measured. It should be noted that when the maximum refractive index in the plane of the polyimide film is set to nx, the minimum is set to ny, the refractive index in the thickness direction is set to nz, and the thickness of the film is set to d, Rth is expressed by the following formula.

[0208] Rth=[{(nx+ny) / 2}-nz]×d

[0209] (5) Elongation at break (Evaluation of ductility)

[0210] The elongation at break was measured by a tensile test (measurement of elongation) in accordance with JIS K 7127. The test piece used had a width of 10 mm and a thickness of 10 to 60 μm.

[0211] (6) Ductility (Evaluation of ductility)

[0212] The polyimide films obtained in the examples and comparative examples were made into test pieces with a width of 10 mm and a thickness of 10 to 60 μm, and subjected to a tensile test (test speed 50 mm / min) in accordance with JIS K 7127 to evaluate ductility. From the perspective of suppressing fractures during manufacturing and in the product, ductility is preferred. The results of the above tests are as follows: those that have undergone plastic deformation beyond the yield point are recorded as ductile, and those that have fractured in the elastic region are recorded as non-ductile.

[0213] (7) Appearance

[0214] The presence or absence of defects (unevenness and voids) on the surface of the polyimide films obtained in Examples and Comparative Examples were evaluated based on the following criteria.

[0215] A: No defects were observed on the film surface.

[0216] B: Slight defects were seen on the film surface (no problem in actual use).

[0217] C: Defects are clearly visible on the film surface (problem with oiling in actual use).

[0218] The tetracarboxylic acid component and the diamine component used in Examples and Comparative Examples, and their abbreviations and the like are as follows.

[0219] <Tetracarboxylic acid component>

[0220] HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.; compound represented by formula (a1))

[0221] <Diamine component>

[0222] BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane (manufactured by Wakayama Seika Industries, Ltd., a compound represented by formula (b11))

[0223] BisAM: 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene (manufactured by Mitsui Fine Chemicals Co., Ltd., a compound represented by formula (b211))

[0224] The details of the solvents and catalysts used in Examples and Comparative Examples are as follows.

[0225] γ-Butyrolactone (Mitsubishi Chemical Corporation)

[0226] N,N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.)

[0227] Triethylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0228] Triethylamine (manufactured by Kanto Chemical Co., Ltd.)

[0229] <Example 1>

[0230] A 0.3 L five-necked glass round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet pipe, a Dean-Stark trap equipped with a condenser, a thermometer, and a glass end cap was used as a reaction apparatus. In the round-bottom flask, 28.858 g (0.070 mol) of BAPP, 10.373 g (0.030 mol) of BisAM, 52.2 g of γ-butyrolactone, and 0.056 g of triethylenediamine and 5.060 g of triethylamine as catalysts were placed, and the mixture was heated to 80° C. under a nitrogen atmosphere while stirring at 150 rpm to obtain a solution. To the solution, 22.439 g (0.100 mol) of HPMDA and 23.0 g of γ-butyrolactone were added simultaneously, and the mixture was heated in a mantle heater to raise the temperature in the reaction system to 190° C. over about 20 minutes. The components removed by distillation were collected, and the temperature in the reaction system was maintained at 190°C for 1 hour and 45 minutes. After adding 156.4 g of N,N-dimethylacetamide, the mixture was stirred at about 100°C for about 1 hour to obtain a uniform polyimide varnish (1) having a solid content concentration of 20% by mass.

[0231] Next, the obtained polyimide varnish (1) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0232] <Example 2>

[0233] Using the same reaction apparatus as in Example 1, 24.641 g (0.060 mol) of BAPP, 13.831 g (0.040 mol) of BisAM, 49.4 g of γ-butyrolactone, and 10.12 g of triethylamine as a catalyst were placed in a round-bottom flask, and the mixture was heated to 80° C. under a nitrogen atmosphere while stirring at 150 rpm to obtain a solution. 22.439 g (0.100 mol) of HPMDA and 11.4 g of γ-butyrolactone were added to the solution simultaneously, and the mixture was heated in a hooded heater to raise the temperature in the reaction system to 190° C. over about 20 minutes. The components removed by distillation were collected, and the temperature in the reaction system was maintained at 190° C. for 4.5 hours. 168.1 g of N,N-dimethylacetamide was added, and the mixture was stirred at about 100° C. for about 1 hour to obtain a uniform polyimide varnish (2) having a solid content concentration of 20% by mass.

[0234] Next, the obtained polyimide varnish (2) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0235] <Example 3>

[0236] Using the same reaction apparatus as in Example 1, 20.534 g (0.050 mol) of BAPP, 17.289 g (0.050 mol) of BisAM, 49.1 g of γ-butyrolactone, and 10.13 g of triethylamine as a catalyst were placed in a round-bottom flask, and the mixture was heated to 80° C. under a nitrogen atmosphere while being stirred at 150 rpm to obtain a solution. 22.439 g (0.100 mol) of HPMDA and 11.1 g of γ-butyrolactone were added to the solution simultaneously, and the temperature in the reaction system was raised to 190° C. over about 20 minutes by heating in a hooded heater. The components removed by distillation were collected, and the temperature in the reaction system was maintained at 190° C. for 7 hours. 166.1 g of N,N-dimethylacetamide was added, and the mixture was stirred at about 100° C. for about 1 hour to obtain a uniform polyimide varnish (3) having a solid content concentration of 20% by mass.

[0237] Next, the obtained polyimide varnish (3) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0238] <Example 4>

[0239] To the polyimide varnish (3) obtained in Example 3, 0.1 parts by mass (calculated as active ingredient) of a fluorine-containing polymer (LE-607DM, manufactured by Kyoeisha Chemical Co., Ltd., 30% dimethylacetamide solution) was added based on 100 parts by mass of the polyimide resin to obtain a polyimide varnish (4).

[0240] Next, the obtained polyimide varnish (4) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0241] <Example 5>

[0242] To the polyimide varnish (3) obtained in Example 3, 0.5 parts by mass (calculated as active ingredient) of a fluorinated polymer (LE-607DM, manufactured by Kyoeisha Chemical Co., Ltd., 30% dimethylacetamide solution) was added based on 100 parts by mass of the polyimide resin to obtain a polyimide varnish (5).

[0243] Next, the obtained polyimide varnish (5) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0244] <Comparative Example 1>

[0245] Using the same reaction apparatus as in Example 1, 16.427 g (0.040 mol) of BAPP, 20.747 g (0.060 mol) of BisAM, 48.5 g of γ-butyrolactone, and 10.10 g of triethylamine as a catalyst were placed in a round-bottom flask, and the mixture was heated to 80° C. under a nitrogen atmosphere while being stirred at 150 rpm to obtain a solution. 22.439 g (0.100 mol) of HPMDA and 11.0 g of γ-butyrolactone were added to the solution simultaneously, and the mixture was heated in a hooded heater to raise the temperature in the reaction system to 190° C. over about 20 minutes. The components removed by distillation were collected, and the temperature in the reaction system was maintained at 190° C. for 7.5 hours. 164.2 g of N,N-dimethylacetamide was added, and the mixture was stirred at about 100° C. for about 1 hour to obtain a uniform polyimide varnish (6) having a solid content concentration of 20% by mass.

[0246] Next, the obtained polyimide varnish (6) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0247] <Comparative Example 2>

[0248] To the polyimide varnish (6) obtained in Comparative Example 1, 0.1 parts by mass (calculated as active ingredient) of a fluorinated polymer (LE-607DM, manufactured by Kyoeisha Chemical Co., Ltd., 30% dimethylacetamide solution) was added based on 100 parts by mass of the polyimide resin to obtain a polyimide varnish (7).

[0249] Next, the obtained polyimide varnish (7) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0250] <Comparative Example 3>

[0251] To the polyimide varnish (6) obtained in Comparative Example 1, 0.5 parts by mass (calculated as active ingredient) of a fluorine-containing polymer (LE-607DM, manufactured by Kyoeisha Chemical Co., Ltd., 30% dimethylacetamide solution) was added based on 100 parts by mass of the polyimide resin to obtain a polyimide varnish (8).

[0252] Next, the obtained polyimide varnish (8) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0253] <Comparative Example 4>

[0254] To the polyimide varnish (6) obtained in Comparative Example 1, 1.0 part by mass (calculated as active ingredient) of a fluorinated polymer (LE-607DM, manufactured by Kyoeisha Chemical Co., Ltd., 30% dimethylacetamide solution) was added based on 100 parts by mass of the polyimide resin to obtain a polyimide varnish (9).

[0255] Next, the obtained polyimide varnish (9) was applied on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 260°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0256] <Comparative Example 5>

[0257] Using the same reaction apparatus as in Example 1, 43.745 g (0.107 mol) of BAPP, 81.4 g of γ-butyrolactone, and 0.54 g of triethylamine as a catalyst were placed in a round-bottom flask, and the mixture was heated to 70° C. under a nitrogen atmosphere while being stirred at 150 rpm to obtain a solution. 23.887 g (0.107 mol) of HPMDA and 20.3 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) were added to the solution, respectively, and the mixture was heated in a hooded heater to raise the temperature in the reaction system to 190° C. over about 20 minutes. The components removed by distillation were collected, and the temperature in the reaction system was maintained at 190° C. for 4.0 hours. 154.2 g of γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) was added, and the mixture was stirred at about 100° C. for about 1 hour to obtain a uniform polyimide varnish (10) having a solid content concentration of 20% by mass.

[0258] Next, the obtained polyimide varnish (10) was coated on a PET substrate and maintained at 100°C for 20 minutes to volatilize the solvent, thereby obtaining a self-supporting transparent primary dried film. The film was further fixed to a stainless steel frame and dried at 210°C in an air atmosphere for 20 minutes to remove the solvent, thereby obtaining a film. The evaluation results of the polyimide film are shown in Table 1.

[0259] [Table 1]

[0260] Table 1

[0261]

[0262] *) The amount of the fluorinated polymer is the amount (parts by mass) relative to 100 parts by mass of the polyimide.

[0263] As shown in Table 1, it can be seen that the polyimide films of Examples are excellent in transparency and optical isotropy, and also excellent in ductility.

Claims

1. A polyimide resin comprising: a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from diamine, The structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1), The structural unit B comprises: a structural unit (B1) derived from a compound represented by the following formula (b11); and At least one structural unit (B2) selected from the group consisting of a structural unit derived from a compound represented by the following formula (b211), a structural unit derived from a compound represented by the following formula (b212), and a structural unit derived from a compound represented by the following formula (b213), The molar ratio of the structural unit (B1) to the structural unit (B2) [(B1) / (B2)] is 55 / 45 to 75 / 25, In formula (b11), R 1 and R 2 Each independently represents a methyl group or a trifluoromethyl group. 2 . The polyimide resin according to claim 1 , which has an elongation at break measured in accordance with JIS K 7127 of 10% or more. 3 . A polyimide resin composition comprising: the polyimide resin according to claim 1 , and at least one selected from the group consisting of a fluorine-containing polymer and a silicone-containing polymer.

4. The polyimide resin composition according to claim 3, wherein The total content of the fluorine-containing polymer and the silicone-containing polymer is 0.01 to 2 parts by mass based on 100 parts by mass of the polyimide resin.

5. The polyimide resin composition according to claim 3 or 4, wherein The fluorine-containing polymer is a fluorine-containing acrylic polymer. 6 . A polyimide varnish, wherein the polyimide resin according to claim 1 or 2 or the polyimide resin composition according to any one of claims 3 to 5 is dissolved in an organic solvent. 7 . A polyimide film comprising: the polyimide resin according to claim 1 or 2 , or the polyimide resin composition according to any one of claims 3 to 5 .

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