Polyimide precursor composition and polyimide film

Abstract

Provided is a polyimide precursor solution composition capable of rapidly stabilizing viscosity and achieving early product shipment. The polyimide precursor solution composition includes: a polyimide precursor having a repeating unit represented by the following general formula (I); and a solvent such as 3-methoxy-N,N-dimethylpropanamide.(In general formula I, 50 mol% or more of X1 is a structure represented by the following formula (1-1) and / or formula (1-2): and 50 mol% or more of Y1 is a structure represented by formula (D-1) and / or (D-2):).

Description

Technical Field

[0001] The present invention relates to a polyimide precursor composition and a polyimide film with improved thermal decomposition resistance, which are suitable for use in electronic devices such as flexible device substrates. Background Technology

[0002] Polyimide films are widely used in electrical / electronic devices, semiconductors, and other fields due to their excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability. On the other hand, with the advent of a highly information-based society, significant progress has been made in recent years in the development of optical materials such as optical fibers and waveguides in the field of optical communication, and in the development of liquid crystal alignment films and color filter protective films in the field of display devices. Particularly in the display device field, research is actively underway on lightweight and highly flexible plastic substrates as a replacement for glass substrates, as well as the development of bendable and rollable displays.

[0003] In displays such as liquid crystal displays (LCDs) and organic EL displays, semiconductor elements such as TFTs are formed to drive each pixel. Therefore, the substrate is required to have heat resistance and dimensional stability. Due to its excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability, polyimide film is expected to become a substrate material for display applications.

[0004] Since polyimide is typically yellowish-brown, its use in transmissive devices such as backlit liquid crystal displays is limited. However, in recent years, polyimide films with excellent light transmittance in addition to mechanical and thermal properties have been developed, and there is growing expectation for them as substrates for display applications (see Patent Documents 1 to 4).

[0005] In the manufacture of polyimide, N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) are commonly used as solvents. On the other hand, Patent Document 5 discloses that certain organic solvents are superior to NMP.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: WO 2012 / 011590

[0009] Patent Document 2: WO 2013 / 179727

[0010] Patent Document 3: WO 2014 / 038715

[0011] Patent Document 4: WO 2022 / 176956

[0012] Patent Document 5: WO 2015 / 186782 Summary of the Invention

[0013] The problem the invention aims to solve

[0014] Patent documents 2 to 4 disclose a polyimide precursor composition obtained by reacting an alicyclic tetracarboxylic acid dianhydride, which is a tetracarboxylic acid component, with an aromatic diamine compound, 4,4'-diaminobenzoylaniline (abbreviated as DABAN), which is a diamine component, in an organic solvent. The polyimide films obtained by imidizing the polyimide precursor compositions described in these documents exhibit excellent light transmittance and are superior in at least one of the following properties: heat resistance (Tg, melting point, etc.), thermal decomposition resistance, mechanical properties (elastic modulus, elongation at break, flexural strength, etc.), and thermal properties (linear coefficient of thermal expansion, etc.); or they possess a good balance of two or more of these properties within their practical applications.

[0015] Polyimide films are manufactured by casting a polyimide precursor solution composition onto a supporting substrate, followed by heating to remove the solvent and promote imidization. Therefore, the viscosity and concentration of the polyimide precursor composition are key factors in manufacturing the desired polyimide film.

[0016] However, the inventors conducted a detailed study on the reaction between the tetracarboxylic acid component containing alicyclic tetracarboxylic acid dianhydride and the diamine component containing DABAN. The results showed that when the proportion of DABAN in the diamine component was large, the viscosity of the polyimide precursor solution composition required a long time to stabilize, which posed a problem in terms of productivity.

[0017] Although Patent Document 5 describes reacting an alicyclic tetracarboxylic dianhydride with a diamine containing DABAN in a polar organic solvent other than NMP, the proportion of DABAN in the diamine is as low as 40 mol%. When the proportion of DABAN is low, there is no viscosity stability problem in the polyimide precursor solution composition, so the problem caused by a high proportion of DABAN is not mentioned.

[0018] This invention was made in view of the problems of the prior art described above, and its main objective is to provide a polyimide precursor composition obtained by reacting a tetracarboxylic acid component containing a tetracarboxylic acid derivative having an alicyclic structure with a diamine component containing DABAN in a high proportion, wherein the viscosity stabilizes rapidly, enabling earlier product shipment. Here, "rapid" and "earlier" refer to, for example, within 4 days after manufacturing.

[0019] Technical means to solve the problem

[0020] The main disclosures of this application are summarized as follows.

[0021] 1. A polyimide precursor composition comprising: Polyimide precursors having repeating units represented by the following general formula (I); and Solvents comprising at least one selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide (MPA), N,N-diethylpropionamide (DEPA), N,N-diethylformamide (DEF), 1,3-dimethyl-2-imidazolium ketone (DMI), N,N-dimethylisobutyramide (DMIB), N,N-dimethylpropionamide (DMPA), N,N-diethylacetamide (DEAc), and 1-butyl-2-pyrrolidone (NBP): [Chemistry 1]

[0022] In general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, and R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms. Wherein, 50 mol% or more (preferably more than 50 mol%) of X1 is represented by the structure shown in formula (1-1) and / or formula (1-2) below: [Chemistry 2]

[0023] [Chemistry 3] ; Furthermore, 50 mol% or more (preferably more than 50 mol%) of Y1 has a structure represented by formula (D-1) and / or (D-2): [Chemistry 4] .

[0024] 2. The polyimide precursor composition as described in Item 1 above, wherein 70 mol% or more of X1 has a structure represented by formula (1-1) and / or formula (1-2), and 70 mol% or more of Y1 has a structure represented by formula (D-1) and / or (D-2).

[0025] 3. The polyimide precursor composition as described in any of the preceding items, comprising a solvent selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide (MPA), N,N-diethylpropionamide (DEPA), N,N-diethylformamide (DEF), 1,3-dimethyl-2-imidazolium ketone (DMI), N,N-dimethylisobutyramide (DMIB), N,N-dimethylpropionamide (DMPA), N,N-diethylacetamide (DEAc), and 1-butyl-2-pyrrolidone (NBP), wherein the amount of said solvent is 70% by mass or more of all solvents contained in the polyimide precursor composition.

[0026] 4. The polyimide precursor composition as described in any of the preceding items, wherein the polyimide film obtained from the polyimide precursor composition has a light transmittance of more than 70% at a wavelength of 400 nm when the film thickness is 10 µm.

[0027] 5. The polyimide precursor composition as described in any of the preceding items, wherein the polyimide film obtained from the polyimide precursor composition has an elongation at break of 8% or more when the film thickness is 10 µm.

[0028] 6. The polyimide precursor composition as described in any of the preceding items, wherein the polyimide film obtained from the polyimide precursor composition has a haze value of less than 1.0% when the film thickness is 10 µm.

[0029] 7. The polyimide precursor composition as described in any of the preceding items, wherein the polyimide precursor composition reaches its maximum viscosity within 4 days when stored at 23°C under an inert gas atmosphere immediately after manufacture.

[0030] 8. The polyimide precursor composition as described in any of the preceding items, wherein the polyimide film obtained from the polyimide precursor composition has a linear coefficient of thermal expansion of less than 20 ppm / K.

[0031] 9. A polyimide film obtained from the polyimide precursor composition described in any one of the preceding items.

[0032] 10. A polyimide film / substrate laminate, comprising: Polyimide films obtained from the polyimide precursor compositions described in any one of the foregoing items; and Support substrate.

[0033] 11. The laminate as described in Item 10, wherein the supporting substrate is a glass substrate.

[0034] 12. A method for manufacturing a polyimide film / substrate laminate, comprising: (a) applying the polyimide precursor composition of any one of the preceding items onto a support substrate; and (b) The polyimide precursor on the support substrate is heat-treated to form a laminate containing a polyimide film on the support substrate.

[0035] 13. The method as described in Item 12, wherein the supporting substrate is a glass substrate.

[0036] 14. A method for manufacturing a flexible electronic device, comprising: (a) Applying the polyimide precursor composition of any one of the preceding items onto a support substrate; (b) The polyimide precursor on the support substrate is heat-treated to obtain a polyimide film / substrate laminate, wherein the polyimide film is laminated on the support substrate; (c) Forming at least one layer selected from conductor layers and semiconductor layers on the polyimide film of the laminate; and (d) Separate the supporting substrate from the polyimide film.

[0037] 15. The method as described in Item 14, wherein the supporting substrate is a glass substrate.

[0038] The effects of the invention

[0039] According to the present invention, a polyimide precursor composition is provided, which is obtained by reacting a tetracarboxylic acid component containing a tetracarboxylic acid derivative having an alicyclic structure with a diamine component containing DABAN in a high proportion, wherein the viscosity stabilizes rapidly, enabling earlier product shipment.

[0040] Furthermore, according to one aspect of the invention, a polyimide film and a polyimide film / substrate laminate obtained using the above-described polyimide precursor composition can be provided. Furthermore, according to another aspect of the invention, a method for manufacturing a flexible electronic device using the said polyimide precursor composition and a flexible electronic device can be provided. Detailed Implementation

[0041] The term "flexible (electronic) device" in this application refers to a device that is flexible in itself, typically with a semiconductor layer (such as transistors or diodes) formed on a substrate to complete the device. This "flexible (electronic) device" differs from devices such as COF (Chip On Film) that mount "rigid" semiconductor components like IC chips on a conventional FPC (Flexible Printed Circuit Board). However, for the operation or control of the "flexible (electronic) device" of this application, "rigid" semiconductor components such as IC chips can also be mounted on a flexible substrate or electrically connected to it for combined use. Suitable flexible (electronic) devices include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as light-receiving devices such as solar cells and CMOS sensors.

[0042] The polyimide precursor composition of the present invention will be described below, followed by a method for manufacturing a flexible electronic device.

[0043] <<Polyimide Precursor Compositions>>

[0044] The polyimide precursor composition for forming a polyimide film comprises a polyimide precursor and a solvent. The polyimide precursor is dissolved in the solvent.

[0045] The polyimide precursor has repeating units represented by the following general formula (I): [Chemistry 5]

[0046] (In general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, and R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0047] Polyamic acids in which R1 and R2 are hydrogen atoms are particularly preferred. When X1 and Y1 are aliphatic groups, the aliphatic group is preferably a group having an alicyclic structure.

[0048] In all repeating units of the polyimide precursor, preferably 50 mol% or more (more preferably greater than 50 mol%) of X1 is a structure represented by the following formula (1-1) and / or formula (1-2), namely, a structure derived from norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (abbreviated as CpODA) and 2,2'-bisnorbornane-5,5',6,6'-tetracarboxylic dianhydride (abbreviated as BNBDA).

[0049] [Chemistry 6]

[0050] [Chemistry 7]

[0051] In all repeating units of the polyimide precursor, Y1 comprises more than 50 mol% (preferably more than 50 mol%) of the structure represented by the following formula (D-1) and / or (D-2), i.e., the structure derived from 4,4'-diaminobenzoylaniline (referred to as DABAN if necessary).

[0052] [Chemistry 8]

[0053] The solvent contained in the polyimide precursor composition of the present invention includes at least one selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide (MPA), N,N-diethylpropionamide (DEPA), N,N-diethylformamide (DEF), 1,3-dimethyl-2-imidazolium ketone (DMI), N,N-dimethylisobutyramide (DMIB), N,N-dimethylpropionamide (DMPA), N,N-diethylacetamide (DEAc), and 1-butyl-2-pyrrolidone (NBP).

[0054] Compared with compositions containing a solvent such as NMP, the composition containing a polyimide precursor and the aforementioned solvent has a stable viscosity within a short time after production, and can shorten the time required until product completion, that is, the turnaround time (TAT). Therefore, it is possible to simplify the production process and achieve a rapid short delivery time, which is of extremely high value from an industrial perspective. In addition, the polyimide film obtained from this composition exhibits properties equivalent to or sometimes even superior to those of a polyimide film obtained from a composition using NMP (N-methyl-2-pyrrolidone) as a solvent.

[0055] Hereinafter, the polyimide precursor will be described by providing the monomers (tetracarboxylic acid component, diamine component and other components) for X1 and Y1 in the general formula (I), and then the production method will be described.

[0056] In the present specification, the tetracarboxylic acid component refers to a tetracarboxylic acid derivative used as a raw material for producing polyimide, and includes tetracarboxylic acids, tetracarboxylic dianhydrides, as well as other tetracarboxylic acid silyl esters, tetracarboxylic acid esters, tetracarboxylic acid chlorides and the like. Although not particularly limited, the use of tetracarboxylic dianhydride is convenient from the viewpoint of production, so examples using tetracarboxylic dianhydride as the tetracarboxylic acid component will be described in the following description. The diamine component is a diamine compound having two amino groups (-NH₂), which is used as a raw material for producing polyimide.

[0057] In the present specification, the polyimide film refers to both a film formed on a supporting (carrier) substrate and present in a laminate, and a film obtained after separating the substrate. In addition, the material constituting the polyimide film, that is, the material obtained by subjecting the polyimide precursor composition to heat treatment (imidization), may also be referred to as a "polyimide material".

[0058] <X1 and Tetracarboxylic Acid Component>

[0059] As described above, in all repeating units of the polyimide precursor, X1 has a structure represented by formula (1-1) and / or formula (1-2) of 50 mol% or more (preferably greater than 50 mol%), more preferably 60 mol% or more, and even more preferably 70 mol% or more. In some embodiments, X1 has a structure represented by formula (1-1) and / or formula (1-2) of 80 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol%. In a particularly preferred embodiment, the proportion of the groups represented by formula (1-1) and / or formula (1-2) is within these ranges (i.e., 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol%), and the total proportion of the groups represented by formula (1-1) and / or formula (1-2) with the proportion of tetravalent groups having other alicyclic structures (hereinafter) is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more; 100 mol% is also very preferred.

[0060] Examples of tetracarboxylic dianhydrides providing the structure of formula (1-1) as X1 include norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (abbreviated as CpODA); examples of tetracarboxylic dianhydrides providing the structure of formula (1-2) include 2,2'-bisnorbornane-5,5',6,6'-tetracarboxylic dianhydride (abbreviated as BNBDA).

[0061] X1 may contain tetravalent groups having alicyclic structures other than those of formula (1-1) and / or formula (1-2). When X1 contains tetravalent groups having other alicyclic structures, preferably at least 3, more preferably 4, bonds are directly bonded to alicyclic groups of the alicyclic structure; in terms of raw materials, preferably at least 3, more preferably 4 of the 4 -COOH groups are directly bonded to tetracarboxylic dianhydrides of the alicyclic structure.

[0062] As a tetravalent group having other alicyclic structures, a tetravalent group having an alicyclic structure with 4 to 40 carbon atoms is preferred, more preferably the group has at least one aliphatic 4 to 12-membered ring, and even more preferably an aliphatic 4-membered ring or an aliphatic 6-membered ring. Preferred examples of tetravalent groups having aliphatic 4-membered rings or aliphatic 6-membered rings include the following groups. However, structures equivalent to formulas (1-2) are excluded.

[0063] [Chemistry 9]

[0064] (where R) 31 To R 38 Each is an independent directly bonded or divalent organic group; R 41 To R 47 and R71 To R 73 Each of these groups is independently selected from the group consisting of the following groups: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-. R 48 (These are organic groups with aromatic or alicyclic structures.)

[0065] R 31 R 32 R 33 R 34 R 35 R 36 R 37 and R 38 Specific examples include direct bonding, organic groups containing aromatic or alicyclic rings, aliphatic hydrocarbon groups having 1 to 6 carbon atoms, or oxygen atoms (-O-), sulfur atoms (-S-), carbonyl bonds, ester bonds, and amide bonds. Direct bonding is particularly preferred.

[0066] Having an aromatic ring as R 31 To R 38 and R 48 Examples of organic groups include the following groups.

[0067] [Chemistry 10]

[0068] (W1 is a directly bonded or divalent organic group; n) 11 up to n 13 Each can independently represent an integer from 0 to 4; R 51 R 52 and R 53 Each group can be an alkyl, halogenated, hydroxyl, carboxyl, or trifluoromethyl group having 1 to 6 carbon atoms.

[0069] Specific examples of W1 include direct bonding, divalent groups represented by the following formula (5), and divalent groups represented by the following formula (6).

[0070] [Chemistry 11]

[0071] (where R in equation (6) 61 To R 68 Each can independently represent either a directly bonded or divalent group represented by formula (5).

[0072] Among them, the following groups are preferred as tetravalent groups having an alicyclic structure.

[0073] [Chemistry 12]

[0074] Examples of aliphatic tetracarboxylic dianhydrides having tetravalent groups with other alicyclic structures include monocyclic alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride and cyclohexane-1,2,4,5-tetracarboxylic dianhydride; and monocyclic alicyclic tetracarboxylic dianhydrides such as [1,1'-bis(cyclohexane)]-3,3',4,4'-tetracarboxylic dianhydride, [1,1'-bis(cyclohexane)]-2,3,3',4'-tetracarboxylic dianhydride, [1,1'-bis(cyclohexane)]-2,2',3,3'-tetracarboxylic dianhydride, and 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic anhydride). , 4,4'-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-thiobis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-sulfonylbis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic anhydride), octahydropentaene-1,3,4,6-tetracarboxylic anhydride, bicyclo[2.2.1] [2.2.1]Heptane-2,3,5,6-Tetracarboxylic dianhydride, 6-(carboxymethyl)bicyclo[2.2.2]Heptane-2,3,5-Tricarboxylic dianhydride, Bicyclo[2.2.2]Octane-2,3,5,6-Tetracarboxylic dianhydride, Bicyclo[2.2.2]Oct-5-en-2,3,7,8-Tetracarboxylic dianhydride, Tricyclo[4.2.2.02,5]Decane-3,4,7,8-Tetracarboxylic dianhydride, Tricyclo[4.2.2.02,5]Decan-7-en-3,4,9,10-Tetracarboxylic dianhydride, 9-Oxatricyclo[4.2.1.02,5]Nonane-3,4, Alicyclic tetracarboxylic dianhydrides, including 7,8-tetracarboxylic dianhydrides, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethylbridged naphthalene-2c,3c,6c,7c-tetracarboxylic dianhydrides, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethylbridged naphthalene-2t,3t,6c,7c-tetracarboxylic dianhydrides, decahydro-1,4-ethbridged-5,8-methylbridged naphthalene-2,3,6,7-tetracarboxylic dianhydrides, and tetradecylhydro-1,4:5,8:9,10-trimethylbridged anthracene-2,3,6,7-tetracarboxylic dianhydrides, are alicyclic tetracarboxylic dianhydrides with two or more rings. These can be used alone or in combination.

[0075] In X1, based on 100 mol% of the tetracarboxylic acid component, the amount of tetravalent groups having alicyclic structures other than formula (1-1) and / or formula (1-2) is preferably 0 to 50 mol%, more preferably 0 to 40 mol%, and even more preferably 0 to 30 mol%.

[0076] In this invention, X1 may contain tetravalent aliphatic or aromatic groups other than those represented by formulas (1-1) and / or (1-2) and tetravalent groups having other alicyclic structures (hereinafter referred to as "other X1"), without impairing the effects of the invention. In other words, the tetracarboxylic acid component may contain other tetracarboxylic acid derivatives besides tetracarboxylic acid derivatives having alicyclic structures, without impairing the effects of the invention. Based on 100 mol% of the tetracarboxylic acid component, the amount of other tetracarboxylic acid derivatives is 30 mol% or less (preferably less than 30 mol%), more preferably 20 mol% or less (preferably less than 20 mol%), and even more preferably 10 mol% or less (preferably less than 10 mol%) (0 mol% is also preferred).

[0077] When “other X1” is a tetravalent group having an aromatic ring, it is preferably a tetravalent group having an aromatic ring with 6 to 40 carbon atoms.

[0078] Examples of tetravalent groups having an aromatic ring include the following groups.

[0079] [Chemistry 13]

[0080] (Where Z1 is a direct bond, or any of the following divalent groups:) [Chemistry 14]

[0081] In the formula, Z2 is a divalent organic group, Z3 and Z4 are independently amide, ester and carbonyl bonds respectively, and Z5 is an organic group containing an aromatic ring.

[0082] Specific examples of Z2 include aliphatic hydrocarbon groups having 2 to 24 carbon atoms and aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0083] Specific examples of Z5 include aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0084] Since the resulting polyimide film can have high heat resistance and high light transmittance, the following groups are particularly preferred as tetravalent groups with aromatic rings.

[0085] [Chemistry 15]

[0086] (Where Z1 is a direct bond or a hexafluoroisopropylidene bond)

[0087] Because the resulting polyimide film can have high heat resistance, high light transmittance and low linear thermal expansion coefficient, Z1 is more preferably direct bonding.

[0088] Furthermore, preferred groups include those in formula (9) above where Z1 is a group containing a fluorene group represented by formula (3A) below: [Chemistry 16]

[0089] Z 11 and Z 12 Each is independently a (preferably identical) single bond or divalent organic group. Z 11 and Z 12 Preferably, it contains an organic group with an aromatic ring, and more preferably has a structure represented, for example, by formula (3A1): [Chemistry 17]

[0090] (Z 13 and Z 14 Each can be independently a single bond, -COO-, -OCO-, or -O-, where, when Z 14 When connected to a fluorene group, Z is preferred. 13 It is -COO-, -OCO-, or -O- and Z 14 It has a single bond structure; R 91 It is an alkyl or phenyl group having 1 to 4 carbon atoms, preferably methyl, and n is an integer from 0 to 4, preferably 1).

[0091] Examples of tetracarboxylic acid components in which X1 is a repeating unit of general formula (I) having an aromatic ring include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, pyromellitic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3 ',4'-Biphenyltetracarboxylic acid, 4,4'-oxyphthalic acid, bis(3,4-dicarboxyphenyl) sulfone, m-terphenyl-3,4,3',4'-tetracarboxylic acid, p-terphenyl-3,4,3',4'-tetracarboxylic acid, dicarboxyphenyl dimethylsilane, bis(dicarboxyphenoxybiphenyl)sulfide, sulfonyl phthalic acid and their derivatives, including tetracarboxylic dianhydride, tetracarboxylic silyl ester, tetracarboxylic ester and tetracarboxylic chloride. Examples of tetracarboxylic acid components of general formula (I) in which X1 is a repeating unit of a tetravalent group having a fluorine-containing aromatic ring include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane and their derivatives, including tetracarboxylic dianhydride, tetracarboxylic silyl ester, tetracarboxylic ester and tetracarboxylic chloride. Furthermore, examples of preferred compounds include (9-hydrofluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid ester). The tetracarboxylic acid component can be used alone or in combination of several.

[0092] <Y1 and diamine component>

[0093] As described above, among all the repeating units of the polyimide precursor, 50 mol% or more (preferably more than 50 mol%) of Y1 is a structure represented by the following formula (D-1) and / or (D-2), more preferably 70 mol% or more (preferably more than 70 mol%), further preferably 80 mol% or more (preferably more than 80 mol%), still more preferably 90 mol% or more (preferably more than 90 mol%), still further preferably 95 mol% or more (preferably more than 95 mol%), and in some embodiments, 100 mol% of Y1 is the structure represented by the following formula (D-1) and / or (D-2). The diamine compound that provides the structures of formula (D-1) and (D-2) as Y1 is 4,4'-diaminobenzanilide (abbreviation: DABAN).

[0094] In the present invention, as Y1, a divalent aliphatic group or aromatic group other than the structures represented by formula (D-1) and (D-2) (abbreviated as "other Y1") may be used within a range that does not impair the effects of the invention. In other words, the diamine component may contain other diamine compounds in addition to DABAN within a range that does not impair the effects of the present invention. Based on 100 mol% of the diamine component, the amount of the other diamine compounds is 50 mol% or less (preferably less than 50 mol%), more preferably 30 mol% or less (preferably less than 30 mol%), further preferably 20 mol% or less (preferably less than 20 mol%), still more preferably 10 mol% or less, still further preferably 5 mol% or less (preferably less than 5 mol%) (0 mol% is also preferred).

[0095] When the "other Y1" is a divalent group having an aromatic ring, it is preferably a divalent group having an aromatic ring with 6 to 40 carbon atoms, more preferably 6 to 20 carbon atoms.

[0096] Examples of the divalent group having an aromatic ring include the following groups.

[0097] [Chem. 18]

[0098] (wherein W1 is a direct bond or a divalent organic group; n 11 to n 13 each independently represent an integer of 0 to 4; and R 51 , R 52 and R 53 are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group or a trifluoromethyl group).

[0099] Specific examples of W1 include direct bonding, divalent groups represented by formula (5) as described below, and divalent groups represented by formula (6) as described below.

[0100] [Chemistry 19]

[0101] [Chemistry 20]

[0102] (where R in equation (6) 61 To R 68 Each can independently represent either a direct bond or any of the divalent groups represented by formula (5).

[0103] Since the resulting polyimide can possess high heat resistance, high light transmittance, and low linear coefficient of thermal expansion, W1 here is particularly preferably directly bonded or selected from the group consisting of groups represented by the following formulas: -NHCO-, -CONH-, -COO-, and -OCO-. Furthermore, W1 is particularly preferably any of the divalent groups represented by formula (6), wherein R 61 To R 68 For direct bonding or selection of one of the groups represented by the following formulas: -NHCO-, -CONH-, -COO-, and -OCO-. However, if -NHCO- or -CONH- is selected, "Other Y1" should be selected to make it different from formulas (D-1) and (D-2).

[0104] Furthermore, preferred groups include those in formula (4) above where W1 is a group containing a fluorene group represented by formula (3B) below: [Chemistry 21]

[0105] Z 11 and Z 12 Each is independently a (preferably identical) single bond or divalent organic group. Z 11 and Z 12 Preferably, it contains an organic group with an aromatic ring, and more preferably has a structure represented, for example, by formula (3B1): [Chemistry 22]

[0106] (Z 13 and Z 14 Each can be independently a single bond, -COO-, -OCO-, or -O-, where, when Z 14 When connected to a fluorene group, Z is preferred. 13 It is -COO-, -OCO-, or -O- and Z 14 It has a single bond structure; R91 It is an alkyl or phenyl group having 1 to 4 carbon atoms, preferably phenyl, and n is an integer from 0 to 4, preferably 1).

[0107] Another preferred group includes compounds in formula (4) above where W1 is a phenylene compound, i.e., a terphenylamine compound, and is particularly preferred to be a compound in which all bonds are in the para position.

[0108] Another preferred group includes W1 in formula (4) above, which represents the first structure in formula (6) containing a single benzene ring, and wherein R 61 and R 62 It is a compound with a 2,2-propylidene group.

[0109] Another preferred group includes W1 in formula (4) above, which is a compound represented by formula (3B2): [Chemistry 23]

[0110] Examples of diamine components providing Y1 as a repeating unit of general formula (I) having a divalent group with an aromatic ring include p-phenylenediamine, m-phenylenediamine, benzidine, 3,3'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, meta-toluidine, 3,4'-diaminobenzoylaniline, N,N'-bis(4-aminophenyl)terephthalamide, N,N'-p-phenylenebis(p-aminobenzoamide), 4-aminophenoxy-4-diaminobenzoic acid, bis(4-aminophenyl)terephthalate, Biphenyl-4,4'-dicarboxylic acid bis(4-aminophenyl) ester, p-phenylene bis(p-aminobenzoic acid), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylic acid ester, [1,1'-biphenyl]-4,4'-dimethylbis(4-aminobenzoic acid), 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy) Benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 3,3'-bis(trifluoromethyl)benzidine, 3,3'-bis((aminophenoxy)phenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(4-(4-aminophenoxy)biphenyl)sulfone, bis(4-(3-aminophenoxy)biphenyl)sulfone Octafluorobenzidine, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-triazine and 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine. Examples of diamine components providing Y1 as a repeating unit of general formula (I) having a divalent group of an aromatic ring containing a fluorine atom include 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, and 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.In addition, preferred diamine compounds include 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1''-terphenyl]-4,4''-diamine, and 4,4'-([1,1'-binaphthyl]-2,2'-diylbis(oxy))diamine. The diamine components can be used alone or in combination.

[0111] When “other Y1” is a divalent group with an alicyclic structure, it is preferably a divalent group with an alicyclic structure of 4 to 40 carbon atoms, more preferably the group has at least one aliphatic 4 to 12-membered ring, and even more preferably an aliphatic 6-membered ring.

[0112] Examples of divalent groups with alicyclic structures include the following groups: [Chemistry 24]

[0113] (where V1 and V2 are each independently a directly bonded or divalent organic group; n) 21 up to n 26 Each can independently represent an integer from 0 to 4; R 81 To R 86 Each is independently an alkyl, halogenated, hydroxyl, carboxyl, or trifluoromethyl group having 1 to 6 carbon atoms; and R 91 R 92 and R 93 Each is independently selected from one of the groups represented by the following formulas: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-).

[0114] Specific examples of V1 and V2 are directly bonded to divalent organic groups represented by formula (5) as described above.

[0115] Since the resulting polyimide can have high heat resistance and low linear coefficient of thermal expansion, the following groups are particularly preferred as divalent groups with alicyclic structures.

[0116] [Chemistry 25]

[0117] Among them, the following groups are preferred as divalent groups with alicyclic structures.

[0118] [Chemistry 26]

[0119] Examples of diamine components in which Y1 is a repeating unit of general formula (I) having an alicyclic structure include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, and 1,3-diaminocyclohexane. Cyclobutane, 1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, diaminodicycloheptane, diaminomethyldicycloheptane, diaminooxydicycloheptane, diaminomethoxydicycloheptane, isophorone diamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirodiindane, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirodiindane. The diamine components can be used alone or in combination.

[0120] As the diamine component providing the repeating unit represented by general formula (I), an aliphatic diamine other than an alicyclic compound may also be used. Based on a total of 100 mol% of the tetracarboxylic acid component and the diamine component, the content of the aliphatic diamine is preferably less than 30 mol%, more preferably less than 20 mol%, and even more preferably less than 10 mol% (inclusive).

[0121] By introducing structures represented by formula (4) as "other Y1", particularly by introducing diamine compounds such as p-phenylenediamine, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, meta-toluidine, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 3,3'-diaminodiphenyl ether, the light transmittance and other physical properties of the resulting polyimide film can be improved in some cases. Furthermore, by introducing structures represented by formula (3B) as "other Y1", particularly by introducing diamine compounds such as 9,9-bis(4-aminophenyl)fluorene, the Tg of the resulting polyimide film can be increased and the phase difference in the thickness direction can be reduced in some cases.

[0122] Solvent

[0123] The solvent contained in the polyimide precursor composition of the present invention includes one or more selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide (MPA), N,N-diethylpropionamide (DEPA), N,N-diethylformamide (DEF), 1,3-dimethyl-2-imidazolium ketone (DMI), N,N-dimethylisobutyramide (DMIB), N,N-dimethylpropionamide (DMPA), N,N-diethylacetamide (DEAc), and 1-butyl-2-pyrrolidone (NBP) (hereinafter sometimes referred to as the solvent group of this application).

[0124] More preferably, the solvent includes at least one selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide (MPA), N,N-diethylpropionamide (DEPA), N,N-diethylformamide (DEF), 1,3-dimethyl-2-imidazolium ketone (DMI), N,N-dimethylisobutyramide (DMIB), N,N-dimethylpropionamide (DMPA), and 1-butyl-2-pyrrolidone (NBP).

[0125] Furthermore, when the solvent contained in the polyimide precursor composition comprises two or more solvents, these two or more solvents can be selected from the solvent group of this application. In one embodiment, it is also preferred to select two or more solvents from the solvent group containing tetramethylurea (TMU). These solvents are also preferred in that they are not designated as substances of very high concern under the EU REACH regulation.

[0126] The content of the solvent selected from the "solvent group of this application" is preferably 50% by mass or more of all solvents contained in the polyimide precursor composition; furthermore, depending on the embodiment, its content is preferably 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, and a content of 100% by mass is also preferred. In the case of containing TMU, it is also preferable to ensure that the total amount of solvent and TMU selected from the "solvent group of this application" falls within the above range. However, based on the total amount of solvent and TMU selected from the "solvent group of this application," depending on the embodiment, the proportion of TMU is 80% by mass or less, 60% by mass or less, 40% by mass or less, or 20% by mass or less.

[0127] In addition to the solvents in the TMU and the "solvent group of this application", the solvents contained in the polyimide precursor composition may also contain "other solvents" within the range that the polyimide precursor can dissolve.

[0128] Examples of other solvents include water, or amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and N-ethyl-2-pyrrolidone; cyclic ester solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, and α-methyl-γ-butyrolactone; carbonate solvents such as ethylene carbonate and propylene carbonate; diol solvents such as triethylene glycol; phenolic solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol; acetophenone, sulfolane, and dimethyl sulfoxide. In addition, other commonly used organic solvents are included, namely phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl acetic acid cellosolve, ethyl acetic acid cellosolve, butyl acetic acid cellosolve, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpentine, mineral oil, and naphtha solvents. Two or more of these solvents may be used in combination as other solvents.

[0129] The polyimide precursor composition of the present invention can be manufactured by reacting a tetracarboxylic acid component with a diamine component in a solvent, particularly in a solvent containing at least one selected from the solvent group of the present application. Based on the chemical structures of R1 and R2, the polyimide precursors used in the present invention (polyimide precursors comprising at least one repeating unit represented by formula (I)) can be classified as follows: 1) Polyamic acid (R1 and R2 are hydrogen atoms), 2) Polyamate (at least a portion of R1 and R2 is alkyl), and 3) 4) Polyamic acid silyl ester (at least a portion of R1 and R2 is alkylsilyl).

[0130] Various polyimide precursors can be readily manufactured using the methods described below. However, the methods for manufacturing the polyimide precursors used in this invention are not limited to those described below.

[0131] 1) Polyamic acid

[0132] The polyimide precursor can be suitably obtained in the form of a polyimide precursor solution by reacting a tetracarboxylic acid dianhydride, which is a tetracarboxylic acid component, with a diamine component in a substantially equimolar ratio in a solvent at a lower temperature below 120°C, for example, while suppressing imidization. Preferably, the molar ratio of the diamine component to the tetracarboxylic acid component [moles of diamine component / moles of tetracarboxylic acid component] is 0.90-1.10, more preferably 0.95-1.05.

[0133] More specifically, the polyimide precursor can be obtained by dissolving a diamine in a solvent, gradually adding a tetracarboxylic dianhydride to the solution while stirring, and then stirring at 0°C-120°C, preferably 5°C-80°C, for 1 hour to 72 hours, although the manufacturing method is not limited to this. When the reaction is carried out above 80°C, the molecular weight changes according to the temperature profile of the polymerization and imidization occurs due to heat, thus sometimes making it impossible to stably produce the polyimide precursor. The order of addition of the diamine and tetracarboxylic dianhydride in the above manufacturing method is preferred because it facilitates an increase in the molecular weight of the polyimide precursor. On the other hand, the order of addition of the diamine and tetracarboxylic dianhydride in the above manufacturing method can also be reversed, which is preferred because it reduces the amount of precipitate.

[0134] 2) Polyamide ester

[0135] Tetracarboxylic acid dianhydride can be reacted with any alcohol to obtain diester dicarboxylic acid, which is then reacted with a chlorinating agent (thionyl chloride, oxalyl chloride, etc.) to obtain diester dicarboxylic acid chloride. Polyimide precursors can be obtained by stirring the diester dicarboxylic acid chloride with a diamine in a solvent at -20°C to 120°C, preferably -5°C to 80°C, for 1 to 72 hours. When the reaction is carried out above 80°C, the molecular weight varies according to the temperature profile of the polymerization, and imidization occurs due to heat, thus sometimes making it difficult to stably produce polyimide precursors. Polyimide precursors can also be easily obtained by dehydrating and condensing the diester dicarboxylic acid with a diamine using phosphorus-based condensing agents, carbodiimide condensing agents, etc.

[0136] 3) Polyamyl silyl ester (indirect method)

[0137] Silylated diamines can be obtained by reacting diamines with a silylating agent beforehand. If necessary, the silyllated diamines can be purified by distillation or other methods. Then, the silyllated diamines are dissolved in a dehydrating solvent, and tetracarboxylic dianhydride is gradually added to the solution while stirring. The mixture is then stirred at 0°C-120°C, preferably 5°C-80°C, for 1 hour to 72 hours to obtain a polyimide precursor. When the reaction is carried out above 80°C, the molecular weight changes according to the temperature profile of the polymerization, and imidization occurs due to heat; therefore, it is sometimes impossible to stably produce polyimide precursors.

[0138] 4) Polyamyl silyl ester (direct method)

[0139] Polyimide precursors can be obtained by mixing a polyamic acid solution obtained using method 1) with a silylating agent, and then stirring at 0°C-120°C, preferably 5°C-80°C, for 1 hour to 72 hours. When the reaction is carried out above 80°C, the molecular weight will vary according to the temperature history of the polymerization, and imidization will occur due to heat, so it is sometimes impossible to stably produce polyimide precursors.

[0140] For the silylating agents used in methods 3) and 4), chlorine-free silylating agents are preferred because purification of the silylated polyamic acid or the resulting polyimide is unnecessary. Examples of chlorine-free silylating agents include N,O-bis(trimethylsilyl)trifluoroacetamide, N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane. N,O-bis(trimethylsilyl)acetamide and hexamethyldisilazane are particularly preferred because they are fluorine-free and inexpensive.

[0141] Meanwhile, in the silylation reaction of diamines in method 3), amine catalysts such as pyridine, piperidine, and triethylamine can be used to promote the reaction. These catalysts can be used as is for the polymerization of polyimide precursors.

[0142] There are no particular restrictions on the manufacture of polyimide precursors, but the monomers and solvents are added to a concentration such that the solid component concentration of the polyimide precursor (mass concentration converted to polyimide) is, for example, 5-45% by mass.

[0143] While there are no particular limitations on the logarithmic viscosity of the polyimide precursor, the logarithmic viscosity of the polyimide precursor in a 0.5 g / dL N-methyl-2-pyrrolidone solution at 30°C is preferably 0.2 dL / g or higher, more preferably 0.3 dL / g or higher, and particularly preferably 0.4 dL / g or higher. When the logarithmic viscosity is 0.2 dL / g or higher, the molecular weight of the polyimide precursor is high, resulting in polyimides with excellent mechanical strength and heat resistance.

[0144] <Imidazole compounds>

[0145] The polyimide precursor composition preferably also contains at least one imidazole compound. The imidazole compound is not particularly limited, as long as it has an imidazole skeleton; examples include 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, and benzimidazole. From the viewpoint of storage stability of the polyimide precursor composition, 2-phenylimidazole and benzimidazole are preferred. Two or more imidazole compounds may be used in combination.

[0146] The content of imidazole compounds in the polyimide precursor composition can be appropriately selected based on the balance between the additive effect and the stability of the polyimide precursor composition. The amount of imidazole compound relative to 1 mole of repeating unit of the polyimide precursor is preferably greater than 0.01 moles but less than 2 moles. The addition of imidazole compounds is effective in improving light transmittance, linear coefficient of thermal expansion, and / or mechanical properties, and within this concentration range, it also has a positive effect on the storage stability of the polyimide precursor composition.

[0147] The content of the imidazole compound relative to 1 mole of repeating unit of the polyimide precursor is more preferably 0.02 moles or more, more preferably 0.025 moles or more, more preferably 0.05 moles or more, and preferably 1.5 moles or less, more preferably 1.2 moles or less, more preferably 1.0 moles or less, more preferably 0.8 moles or less, and most preferably 0.6 moles or less.

[0148] The addition of imidazole compounds improves the storage stability of polyimide precursor compositions, which is particularly advantageous from the viewpoints of transportation, distribution, and storage. Storage stability is significantly improved when the polyimide concentration (solids concentration) is high, especially when applied to solutions where the solids concentration in the composition is 10% by mass or more, preferably 15% by mass or more. Furthermore, compositions with a particularly effective effect are those with a large proportion of formula (1-1) and / or formula (1-2) in X1 of general formula (I), and / or those with a large proportion of formula (D-1) and / or (D-2) in Y1. The effect is particularly pronounced for compositions where the proportion of formula (1-1) and / or formula (1-2) in X1 is 80% or more, preferably 90% or more, and the proportion of formula (D-1) and / or (D-2) in Y1 is 80% or more, preferably 90% or more.

[0149] <Properties of Polyimide Precursor Compositions>

[0150] There is no particular limitation on the concentration of the polyimide precursor in the polyimide precursor composition, but it is typically 5% to 45% by mass, preferably 8% to 25% by mass, and more preferably 10% to 20% by mass, based on the mass concentration converted from polyimide (hereinafter also referred to as the solids concentration). Here, the mass converted from polyimide refers to the mass when all repeating units are completely imidized. Generally, since the polyimide precursor composition is obtained by reacting the tetracarboxylic acid component and the diamine component in a solvent in a specified amount and using them as is, the solids concentration of the polyimide precursor composition is approximately equal to the amount of tetracarboxylic acid component and the diamine component added. The concentration can also be adjusted by diluting or concentrating the solution as needed.

[0151] While there are no particular limitations on the viscosity (rotational viscosity) of the polyimide precursor composition of the present invention, an E-type rotational viscometer was used at a temperature of 25°C and a shear rate of 20 sec. -1 The rotational viscosity measured is preferably 0.01-1000 Pa·sec, more preferably 0.1-100 Pa·sec, even more preferably 0.5-20 Pa·sec, and still more preferably 1-10 Pa·sec. Furthermore, thixotropy can be imparted as needed. When the viscosity is within the above range, the composition is easy to handle during coating or film formation, the varnish exhibits less rejection and excellent leveling properties, thus resulting in a good film.

[0152] The fabrication of the membrane will be described in detail later. The polyimide precursor composition is cast onto a support substrate, and imidization and desolventization are performed by heat treatment to form a polyimide film, thereby obtaining a laminate of the support substrate and the polyimide film (polyimide film / substrate laminate).

[0153] In the process of forming films during device manufacturing, coating machines such as slit coaters with slits as discharge outlets are used. Generally, if the viscosity is too high, discharge becomes difficult, or the coating speed decreases, leading to a reduction in production throughput; conversely, if the viscosity is too low, stable casting may become difficult. Therefore, the polyimide precursor composition used in the industrial device manufacturing process needs to have an appropriate viscosity that matches the slit spacing, and the thickness of the cast film is affected by the viscosity. On the other hand, since the thickness of the polyimide film depends on the product of the solids concentration of the polyimide precursor composition and the thickness of the cast film, if the concentration is made too low in order to adjust to a suitable coating viscosity, it becomes impossible to manufacture a polyimide film with the specified thickness. In this invention, by using a solvent selected from the "solvent group of this application," an appropriate solids concentration can be achieved at an appropriate viscosity.

[0154] The viscosity of the solution composition containing the polyimide precursor represented by formula (I) increases over time after manufacturing, reaching a maximum viscosity. During the period prior to reaching the maximum viscosity, the composition exhibits significant viscosity changes, making it unsuitable for use. This is because viscosity changes lead to variations in the thickness of the cast film, which in turn affects the thickness of the polyimide film, or require significant adjustments to the coating machine settings, rendering the process impractical. After reaching the maximum viscosity, the viscosity of the composition gradually decreases; however, because this decrease is extremely slow, this period becomes the viscosity stabilization period during which the composition can be practically used.

[0155] When a solvent selected from the "solvent group of this application" is used, even if the polyimide precursor composition contains a polyimide precursor represented by formula (I), the composition will reach its maximum viscosity within a short period of time, particularly within 4 days, more preferably within 3 days, and most preferably within 2 days. That is, the composition transitions to a viscosity-stable period in which it can be used earlier. The maximum viscosity reached when the solids concentration (varnish concentration) of the composition is in the range of 10% to 20% by mass is preferably 0.5-10 Pa·sec, more preferably 1-8 Pa·sec.

[0156] The polyimide precursor composition of the present invention may contain, as needed, chemical imidizing agents (acetic anhydrides such as acetic anhydride, and amine compounds such as pyridine and isoquinoline), antioxidants, ultraviolet absorbers, fillers (including inorganic particles such as silica), dyes, pigments, coupling agents such as silane coupling agents, primers, flame retardants, defoamers, leveling agents, rheology control agents (flow promoters), etc.

[0157] In the presence of an imidazole compound, the composition can be prepared by adding and mixing an imidazole compound or a solution of an imidazole compound into the polyimide precursor composition obtained after the reaction, and then mixing them. Alternatively, the tetracarboxylic acid component can be reacted with the diamine component in the presence of the imidazole compound.

[0158] <<Applications of Polyimide Precursor Compositions and Physical Properties of Membranes>>

[0159] Polyimides and polyimide films can be manufactured using the polyimide precursor compositions of the present invention. There are no particular limitations on the manufacturing method; any known imidization method can be appropriately applied. The resulting polyimides can be in the form of films, laminates of polyimide films with other substrates, coatings, powders, beads, molded bodies, foams, etc.

[0160] Depending on the application, the thickness of the polyimide film is preferably 1 µm or more, more preferably 2 µm or more, even more preferably 5 µm or more, and for example, 250 µm or less, preferably 150 µm or less, more preferably 100 µm or less, even more preferably 50 µm or less.

[0161] The polyimide film of the present invention exhibits excellent light transmittance, mechanical properties, thermal properties, and heat resistance. Here, "heat resistance" is related to phase transition (indicators such as glass transition temperature and melting temperature) and thermal decomposition (indicators such as weight loss). Since these are different phenomena, they are not directly related. The polyimide and polyimide film of the present invention exhibit excellent performance in both glass transition temperature (Tg) and thermal decomposition resistance.

[0162] The evaluation of the thermal decomposition resistance of polyimide films (or the polyimides constituting them) can be based on the characteristics required in the manufacturing process of flexible electronic devices, etc. For example, it can be evaluated by the 1% weight loss temperature of the polyimide film. The 1% weight loss temperature is preferably 470°C or higher, more preferably 480°C or higher, and even more preferably 490°C or higher. When the 1% weight loss temperature is within the "preferred range," the thermal decomposition resistance of the material is considered significantly improved. If it is within the "more preferred range," the thermal decomposition resistance of the material is considered significantly improved. If it is within the "further preferred range," the thermal decomposition resistance of the material is considered substantially improved. A higher 1% weight loss temperature increases the process margin, which is beneficial for the stable manufacturing of flexible electronic devices.

[0163] The polyimide film of the present invention has an extremely low coefficient of linear thermal expansion. In one embodiment of the present invention, when measured using a film with a thickness of 10 µm, the coefficient of linear thermal expansion (CTE) of the polyimide film at 150°C to 250°C is preferably less than 20 ppm / K, more preferably less than 20 ppm, further preferably less than 15 ppm / K, and even more preferably less than 11 ppm / K.

[0164] In one embodiment of the present invention, the glass transition temperature (Tg) of the polyimide film (or the polyimide constituting it) is preferably 390°C or higher, more preferably 400°C or higher, even more preferably 410°C or higher, even more preferably 415°C or higher, even more preferably 420°C or higher, even more preferably 425°C or higher, even more preferably 430°C or higher, even more preferably 435°C or higher, and most preferably 440°C or higher.

[0165] In one embodiment of the present invention, when measuring using a film with a thickness of 10 µm, the transmittance of the polyimide film at 400 nm is preferably 70% or more, more preferably 73% or more, further preferably 75% or more, and even more preferably 80% or more. Furthermore, when measuring using a film with a thickness of 10 µm, the yellowness index (YI) of the polyimide film is preferably 6.0 or less, more preferably 5.5 or less, even more preferably 5.0 or less, and even more preferably 4.5 or less. Generally, it is preferably 0 or more.

[0166] In one embodiment of the invention, when measuring using a film with a thickness of 10 µm, the haze value of the polyimide film is preferably less than 1.0%, more preferably less than 0.8%, and even more preferably less than 0.7%. For example, if the haze value exceeds 1%, it is unsuitable for optical applications because the white turbidity is visually identifiable.

[0167] Here, the optical properties are explained. 400 nm light transmittance can be used as an indicator to infer and evaluate the yellowness and transparency of the film. For example, fully aromatic polyimide films such as Upilex-S (Upilex is a registered trademark of Ube Industries) and Kapton (a registered trademark) are typically yellowish-brown. This is because they absorb wavelengths (violet to blue light) in the visible light region from 380 nm to 500 nm. When targeting a colorless and highly transparent polyimide film like the one described in this application, a higher 400 nm light transmittance is preferred.

[0168] The yellow index (YI) is calculated from the color system (e.g., the tristimulus values ​​of X, Y, and Z) obtained from the transmitted wavelength (transmittance). Ideally, white has a yellow index of 0; a hue shift towards yellow is positive, and a hue shift towards blue is negative. Therefore, for polyimide films, a yellow index closer to 0 is preferred. Incidentally, the yellow index is an indicator of the relative relationship between the tristimulus values; therefore, even if the transmittance at 400 nm is low, if the transmittance in other visible light regions is also low, the yellow index will not increase. Thus, it is not a value representing the transparency of the film.

[0169] Haze (turbidity) is an indicator of the degree of "blurriness or turbidity" of a membrane, representing the ratio of transmitted scattered light to total transmitted light (transmitted scattered light / total transmitted light × 100). A light receiver fitted to a standard visual curve is used. A lower haze value is preferred. When the haze value exceeds 1%, the turbidity is visually perceptible as white mist.

[0170] In this application, total light transmittance (or total light transmittance) refers to the average transmittance over the entire visible light region (380 nm to 780 nm). On the other hand, in haze measurement, the transmittance (percentage) that includes both the parallel and diffuse components of light transmitted through the film (sample) is also called "total light transmittance," which may cause confusion. Haze measurement uses a D65 light source (average daylight) and a receiver fitted to a standard spectroscopic visual curve V(λ) (equivalent to the colorimetric function y(λ)). Therefore, the region that peaks near 555 nm is given greater weight, while the transmittance near 400 nm contributes almost nothing to "total light transmittance." Therefore, it should be noted that the "total light transmittance" measured by a haze meter is different from the total light transmittance (or total light transmittance) of this application and does not represent the overall transmittance of the visible light region.

[0171] Furthermore, in one embodiment of the present invention, when a film with a thickness of 10 µm is used for measurement, the elongation at break of the polyimide film is preferably greater than 6%, more preferably 7% or more, and even more preferably 8% or more, 9% or more, and 10% or more, respectively.

[0172] In another preferred embodiment of the invention, the tensile strength of the polyimide film is preferably 150 MPa or more, more preferably 170 MPa or more, even more preferably 180 MPa or more, even more preferably 200 MPa or more, and even more preferably 210 MPa or more. As the tensile strength, a value obtained, for example, from a film with a thickness of about 5-100 µm can be used.

[0173] It is particularly preferred that the desired properties of the polyimide film described above are simultaneously satisfied.

[0174] Polyimide films can be manufactured using known methods. A typical method involves casting a polyimide precursor composition onto a support substrate and then heating and imidizing the support substrate to obtain a polyimide film. This method, combined with the manufacture of a polyimide film / substrate laminate, is described below. Alternatively, a polyimide film can also be obtained by casting a polyimide precursor composition onto a support substrate and heating and drying it to form a self-supporting film, peeling the self-supporting film off the substrate, for example, by holding both sides of the film in a degassed state using a tenter frame and performing thermal imidization.

[0175] <<Fabrication of Polyimide Film / Substrate Laminates and Flexible Electronic Devices>>

[0176] Polyimide film / substrate laminates can be manufactured using the polyimide precursor composition of the present invention. The polyimide film / substrate laminate is manufactured by: (a) coating the polyimide precursor composition onto a support substrate; and (b) heat-treating the polyimide precursor on the support substrate to form a laminate, wherein the polyimide film is laminated on the support substrate (polyimide film / substrate laminate). The method for manufacturing a flexible electronic device of the present invention includes using the polyimide film / substrate laminate manufactured by steps (a) and (b) above, and further includes the steps of: (c) forming at least one layer selected from conductor layers and semiconductor layers on the polyimide film of the laminate; and (d) separating the substrate from the polyimide film.

[0177] First, in step (a), the polyimide precursor composition is cast onto a substrate, and imidized and desolventized by heat treatment to form a polyimide film, thereby obtaining a laminate supporting the substrate and the polyimide film (polyimide film / substrate laminate).

[0178] Heat-resistant materials are used as the supporting substrate. For example, plate-shaped or sheet-shaped substrates made of ceramic materials (glass, alumina, etc.), metallic materials (iron, stainless steel, copper, aluminum, etc.), semiconductor materials (silicon, compound semiconductors, etc.), or film-shaped or sheet-shaped substrates made of heat-resistant plastic materials (polyimide, etc.) are used. Generally, flat and smooth plate-shaped substrates are preferred, typically using: glass substrates such as soda-lime glass, borosilicate glass, alkali-free glass, sapphire glass, etc.; semiconductor (including compound semiconductor) substrates such as silicon, GaAs, InP, GaN, etc.; and metallic substrates such as iron, stainless steel, copper, aluminum, etc.

[0179] Glass substrates are particularly preferred as supporting materials. Flat, smooth, and large-area glass substrates have been developed and are readily available. The thickness of the plate-like substrate, such as the glass substrate, is not limited, but from the viewpoint of ease of handling, it is, for example, 20 µm to 4 mm, preferably 100 µm to 2 mm. The size of the plate-like substrate is not particularly limited, but one side (the long side in the case of a rectangle) is, for example, about 100 mm to 4000 mm, preferably about 200 mm to 3000 mm, and more preferably about 300 mm to 2500 mm.

[0180] These substrates, such as glass substrates, can have inorganic thin films (e.g., silicon oxide films) or resin films formed on their surfaces.

[0181] There are no particular limitations on the method of casting the polyimide precursor composition onto the substrate, and examples include slot coating, die coating, doctor blade coating, spray coating, inkjet coating, nozzle coating, spin coating, screen printing, bar coating, electrodeposition and other conventionally known methods.

[0182] In step (b), the polyimide precursor composition is heat-treated on a supporting substrate to convert it into a polyimide film, thereby obtaining a polyimide film / substrate laminate. The heat treatment conditions are not particularly limited. For example, it is preferable to dry the material in a temperature range of 50°C to 150°C, followed by treatment at a maximum heating temperature of, for example, 150°C to 600°C, preferably 200°C to 550°C, and more preferably 250°C to 500°C.

[0183] The thickness of the polyimide film is preferably 1 µm or more, more preferably 2 µm or more, and even more preferably 5 µm or more. If the thickness is less than 1 µm, the polyimide film cannot maintain sufficient mechanical strength, and for example, when used as a substrate for flexible electronic devices, it may not be able to withstand stress and may crack. Furthermore, the thickness of the polyimide film is preferably 100 µm or less, more preferably 50 µm or less, and even more preferably 20 µm or less. As the thickness of the polyimide film increases, it may become difficult to reduce the thickness of the flexible device. In order to make it thinner while maintaining sufficient durability as a flexible device, the thickness of the polyimide film is preferably 2-50 µm.

[0184] In this invention, the warpage of the polyimide film / substrate laminate is preferably small. Details of the measurement are described in Japanese Patent No. 6798633. In one embodiment, when evaluating the properties of the polyimide film in the polyimide film / silicon substrate (wafer) laminate by the residual stress between the polyimide film and the silicon substrate, the residual stress is preferably less than 27 MPa. Here, it is assumed that the polyimide film is placed in a dry state at 23°C.

[0185] The polyimide film in the polyimide film / substrate laminate may have a second layer, such as a resin film or an inorganic film, on its surface. That is, after forming a polyimide film on a substrate, a second layer can be laminated to form a flexible electronic device substrate. It preferably has at least an inorganic film, and particularly preferably a film that functions as a barrier layer against water vapor, oxygen (air), etc. Examples of water vapor barrier layers include those containing silicon nitride (SiN). x ), silicon dioxide (SiO) x ), silicon oxynitride (SiO) x N y Inorganic films are composed of inorganic materials from the group consisting of metal oxides, metal nitrides, and metal nitrides, such as alumina (Al₂O₃), titanium dioxide (TiO₂), and zirconium oxide (ZrO₂). Common methods for forming these films include physical vapor deposition (PVD) methods such as vacuum evaporation, sputtering, and ion plating, as well as chemical vapor deposition (CVD) methods such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD). This second layer can also be multilayered.

[0186] When the second layer has multiple layers, resin films and inorganic films can be combined, examples of which include laminates obtained by forming a barrier layer / polyimide layer / barrier layer three-layer structure on a polyimide film in a polyimide film / substrate laminate.

[0187] In step (c), using the polyimide / substrate laminate obtained in step (b), at least one layer selected from conductor layers and semiconductor layers is formed on the polyimide film (including a second layer such as an inorganic film deposited on the surface of the polyimide film). These layers may be formed directly on the polyimide film (including the second layer), or they may be formed on the surface of other deposited (laminated) layers required for the device, i.e., indirectly on the polyimide film.

[0188] For the conductor layer and / or semiconductor layer, the appropriate conductor layer and (inorganic or organic) semiconductor layer are selected according to the components and circuits required by the target electronic device. When forming at least one of the conductor layer and semiconductor layer in step (c) of the present invention, it is also preferable to form at least one of the conductor layer and semiconductor layer on the polyimide film on which the inorganic film has been formed.

[0189] The conductor layer and semiconductor layer include layers formed on the entire surface of the polyimide film and layers formed on a portion of the polyimide film. In this invention, step (d) can be performed immediately after step (c), or step (d) can be performed after forming at least one layer selected from the conductor layer and semiconductor layer in step (c) and forming other device structures after step (c).

[0190] When manufacturing a TFT liquid crystal display device as a flexible device, metal wiring, TFTs made of amorphous silicon or polycrystalline silicon, and transparent pixel electrodes are formed, for example, on a polyimide film on which an inorganic film is formed over the entire surface, as needed. The TFT includes, for example, a gate metal layer, a semiconductor layer (e.g., an amorphous silicon film), a gate insulating layer, and wiring connected to the pixel electrodes. The required structure for a liquid crystal display can then be formed on top of this using known methods. Furthermore, transparent electrodes and color filters can also be formed on the polyimide film.

[0191] In the manufacture of organic EL displays, transparent electrodes, light-emitting layers, hole transport layers, electron transport layers, etc., are formed on polyimide films on which inorganic films are formed throughout the entire surface, as required, and TFTs are formed as required.

[0192] Since the polyimide film preferred by the present invention has excellent properties such as heat resistance and toughness, there are no particular limitations on the methods for forming the circuits, components and other structures required for the device.

[0193] Next, in step (d), the supporting substrate is separated from the polyimide film. The separation method can be a mechanical separation method, which physically separates the substrate by applying external force, or a so-called laser separation method, which separates the substrate by applying a laser beam from the substrate surface.

[0194] After separating the support substrate, the device is completed by forming or assembling the required structure or components on a (semi) article having a polyimide film as a substrate.

[0195] As another method for manufacturing flexible electronic devices, after manufacturing a polyimide film / substrate laminate and separating the polyimide film by step (b) above, at least one layer selected from conductor layers and semiconductor layers and necessary structures are formed on the polyimide film as described in step (c) above, thereby manufacturing a (semi) article using a polyimide film as a substrate.

[0196] Example

[0197] The present invention will be further described below with reference to embodiments and comparative examples. However, the present invention is not limited to the embodiments described below.

[0198] In the following embodiments, the evaluation was performed using the following methods.

[0199] Evaluation of Polyimide Films

[0200] [400 nm light transmittance]

[0201] The light transmittance at 400 nm of a 10 µm thick polyimide film was determined using a UV-Vis spectrophotometer V-650DS (manufactured by JASCO Corporation).

[0202] [Yellow Index (YI)]

[0203] The YI of the polyimide film was determined according to ASTEM E313 standard using a UV-Vis spectrophotometer / V-650DS (manufactured by JASCO Corporation). The light source was D65, and the viewing angle was 2°.

[0204] [Elastic modulus, elongation at break, tensile strength]

[0205] A polyimide film with a thickness of approximately 10 µm was cut into dumbbell shapes according to the IEC 450 standard as specimens. The initial elastic modulus, elongation at break, and tensile strength were determined using a TENSILON manufactured by Orientec Co., Ltd. at a clamping distance of 30 mm and a tensile speed of 2 mm / min.

[0206] [Coefficient of linear thermal expansion (CTE)]

[0207] A polyimide film with a thickness of approximately 10 µm was cut into rectangles with a width of 4 mm to serve as specimens. Using a TMA / SS6100 (manufactured by SII Nanotechnology Inc.), the specimens were heated to 500 °C with a clamping distance of 15 mm, a load of 2 g, and a heating rate of 20 °C / min. The linear coefficient of thermal expansion from 150 °C to 250 °C was determined from the resulting TMA curves.

[0208] [1% weight reduction in temperature]

[0209] A polyimide film with a thickness of approximately 10 µm was used as the specimen. A thermogravimetric analyzer (Q5000IR) manufactured by TA Instruments Inc. was used to heat the film from 25 °C to 600 °C in a nitrogen atmosphere at a heating rate of 10 °C / min. The 1% weight reduction temperature was determined from the resulting weight curve, with the weight at 150 °C taken as 100%.

[0210] [Haze]

[0211] According to JIS K7136 standard, the haze of a polyimide film with a thickness of approximately 10 µm and a size of 5 square centimeters was measured using a turbidimeter / NDH2000 (manufactured by Nippon Denshoku Industries).

[0212] Dead-fold test

[0213] Fold a membrane sample measuring 3 cm in length and 1 cm in width in half at the center (approximately 1.5 cm along the length). Press the folded portion with your finger to create a firm crease. After unfolding the membrane, visually inspect the membrane for any creases or cracks and rate it "○"; for creases, rate it "Δ"; and for ruptures, rate it "×".

[0214] Evaluation of Polyimide Precursor Compositions (Varnish)

[0215] [Evaluation of the uniformity of the polyimide precursor composition]

[0216] Visually inspect the polyimide precursor compositions obtained immediately after manufacturing. Compositions without turbidity are rated as "homogeneous," while compositions with turbidity are rated as "non-homogeneous."

[0217] Viscosity determination of polyimide precursor compositions

[0218] Using a TV-22E rotational viscometer manufactured by Toki Sangyo Co., Ltd., at a temperature of 25°C and a 50-second interval... -1 The rotational viscosity of the polyimide precursor composition (varnish) was determined at a shear rate of 0.

[0219] The viscosity of the polyimide precursor composition (varnish) on the day of manufacture (right after manufacture) is defined as day 0 (initial viscosity). The composition is stored at 23°C under an inert gas atmosphere, and its viscosity is measured daily (approximately 24 hours). The number of days from day 0 to the day when the maximum viscosity is reached is recorded as the viscosity stabilization period.

[0220] <Ingredients>

[0221] The abbreviations and purities of the raw materials used in the following embodiments are as follows.

[0222] [Diamine component]

[0223] DABAN: 4,4'-Diaminobenzoylaniline

[0224] 4,4-ODA: 4,4'-Diaminodiphenyl ether

[0225] PPD: p-phenylenediamine

[0226] BAPB: 4,4'-bis(4-aminophenoxy)biphenyl

[0227] BAFL: 9,9-bis(4-aminophenyl)fluorene

[0228] m-TD: Meta-toluidine

[0229] TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0230] [Tetracarboxylic acid component]

[0231] CpODA: norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride

[0232] BNBDA: 2,2'-Dinorbornene-5,5',6,6'-tetracarboxylic dianhydride

[0233] PMDA-H: Cyclohexane-1,2,4,5-tetracarboxylic dianhydride

[0234] [Imidazole compounds]

[0235] 2-Pz: 2-Phenylidene

[0236] 1,2-DMz: 1,2-Dimethylimidazole

[0237] [solvent]

[0238] MPA: 3-Methoxy-N,N-Dimethylpropionamide

[0239] DEPA: N,N-Diethylpropionamide

[0240] DEF: N,N-Diethylformamide

[0241] DMI: 1,3-Dimethyl-2-imidazolidineone

[0242] DMIB: N,N-Dimethylisobutyramide

[0243] DMPA: N,N-Dimethylpropionamide

[0244] DEAc: N,N-Diethylacetamide

[0245] NBP: 1-Butyl-2-pyrrolidone

[0246] NMP: N-methyl-2-pyrrolidone

[0247] DMAc: N,N-dimethylacetamide

[0248] GBL: γ-Butyrolactone

[0249] TMU: Tetramethylurea

[0250] Table 1 shows the structural formulas of the tetracarboxylic acid component, the diamine component, and the imidazole compound.

[0251] [Table 1]

[0252] <Example 1>

[0253] [Preparation of polyimide precursor compositions]

[0254] In a nitrogen-purged reaction vessel, 2.27 g (0.010 mol) of DABAN and 32.11 g of 3-methoxy-N,N-dimethylpropionamide (MPA) were added to make the total mass of the monomers (the sum of the diamine and carboxylic acid components) 16% by mass, and the mixture was stirred at 50°C for 1 hour. Then, 3.84 g (0.010 mol) of CpODA was gradually added to the solution. After stirring at 70°C for 4 hours, a homogeneous and viscous polyimide precursor composition was obtained.

[0255] The initial viscosity (viscosity immediately after manufacture) of the obtained polyimide precursor composition was measured, and the composition was then stored in a sealed container filled with nitrogen at 23°C. Viscosity was then measured daily (approximately every 24 hours). The number of days until the observation of the maximum viscosity was defined as the viscosity stabilization period. The results are shown in Table 2.

[0256] [Manufacturing of polyimide films]

[0257] A 6-inch Eagle-XG (registered trademark) glass substrate (500 µm thick) manufactured by Corning was used as the glass substrate. A polyimide precursor composition was coated onto the glass substrate, and the substrate was thermally imidized by heating from room temperature to 420 °C under a nitrogen atmosphere (oxygen concentration below 200 ppm) to obtain a polyimide film / substrate laminate. The laminate was then immersed in water at 40 °C (e.g., a temperature range of 20 °C–100 °C) to separate the polyimide film from the glass substrate. After drying, the properties of the polyimide film were evaluated. The film thickness of the polyimide film was approximately 10 µm. The evaluation results are shown in Table 2.

[0258] <Examples 2-39, Comparative Examples 1-9>

[0259] The polyimide precursor composition was obtained in the same manner as in Example 1, except that the monomer composition, amount of imidazole compound, solvent, and varnish concentration were changed to those described in Tables 2 through 7. The values ​​listed in the dianhydride entries in the tables represent the content of each component relative to 100 mol% of the total dianhydride. The values ​​listed in the diamine entries in the tables represent the content of each component relative to 100 mol% of the total diamine. The values ​​listed in the solvent entries in the tables represent the content of each solvent relative to 100 wt% of the total solvent. The homogeneity and viscosity stability of the obtained polyimide precursor composition were evaluated in accordance with the method described in Example 1. Note that the polyimide precursor compositions of the examples and comparative examples for which values ​​are listed in the imidazole compound column are varnishes, which were obtained by adding 2-phenylimidazolium or 1,2-dimethylimidazolium as imidazole compounds to the solution after the reaction. The listed values ​​represent the number of moles of imidazole compound relative to each mole of repeating unit (each mole of tetracarboxylic dianhydride and each mole of diamine) of the polyimide precursor.

[0260] Subsequently, the polyimide film was prepared by heating to the curing temperature listed in the table in the same manner as in Example 1. In the comparative examples where the curing temperature was not listed, no polyimide film was prepared. The evaluation results of the films are shown in Tables 2 to 7.

[0261] <Evaluation Results>

[0262] In the examples using the solvents specified in this application, a viscosity stabilization period of up to 3 days was observed, indicating excellent viscosity stabilization. In contrast, in Comparative Examples 1, 2, 3, 7, 8, and 9 using NMP or DMAc as solvents, the viscosity stabilization period was more than 5 days, indicating that viscosity stabilization required a longer period of time.

[0263] In Comparative Example 4, which used GBL as a solvent, the polymerized composition was non-uniform, indicating that it was not suitable for the monomer composition of this application, and therefore no further evaluation was conducted.

[0264] Comparative Examples 5 and 6 are examples using the conventional solvent NMP and where the proportion of DABAN in the diamine component is less than 50 mol%. In Comparative Example 5, where the proportion of DABAN is 0 mol% (ODA is 100 mol%), the viscosity of the polyimide precursor composition stabilizes within 1 day; in Comparative Example 6, where the proportion of DABAN is 40 mol% (ODA is 60 mol%), the viscosity stabilizes within 3 days; both achieve viscosity stability early. This indicates that for polyimide precursor compositions where the proportion of DABAN as the diamine component is less than 50 mol%, there is no problem of "slow viscosity stabilization" even when using NMP as a solvent. In other words, it demonstrates that the viscosity stability problem in the composition is unique to polyimide precursor compositions obtained by reacting a tetracarboxylic acid component containing a large amount of alicyclic compounds with a diamine component containing a large amount of DABAN.

[0265] Furthermore, the polyimide films formed from the polyimide precursor compositions of the examples exhibited satisfactory mechanical, thermal, and optical properties, while the films of Comparative Examples 1, 3, and 7 had lower elongation at break and developed cracks in the dead bending test.

[0266] [Table 2]

[0267] [Table 3]

[0268] [Table 4]

[0269] [Table 5]

[0270] [Table 6]

[0271] [Table 7]

[0272] Industrial availability

[0273] This invention is applicable to the manufacture of flexible electronic devices, such as display devices like liquid crystal displays, organic EL displays, and electronic paper, as well as light-receiving devices like solar cells and CMOS sensors.

Claims

1. A polyimide precursor composition comprising: A polyimide precursor having repeating units represented by the following general formula (I); and Solvents comprising at least one selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-diethylformamide, 1,3-dimethyl-2-imidazolidineone, N,N-dimethylisobutyramide, N,N-dimethylpropionamide, N,N-diethylacetamide, and 1-butyl-2-pyrrolidone: [Chemistry 1] in, In general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, and R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms. Where X1 comprises 50 mol% or more of the structure represented by the following formula (1-1) and / or formula (1-2): [Chemistry 2] [Chemistry 3] ； Furthermore, more than 50 mol% of Y1 has a structure represented by formula (D-1) and / or (D-2): [Chemistry 4] 。 2. The polyimide precursor composition of claim 1, wherein, X1 has 70 mol% or more of the structure represented by formula (1-1) and / or formula (1-2), and Y1 has 70 mol% or more of the structure represented by formula (D-1) and / or (D-2).

3. The polyimide precursor composition of claim 1, comprising a solvent selected from the group consisting of 3-methoxy-N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-diethylformamide, 1,3-dimethyl-2-imidazolium ketone, N,N-dimethylisobutyramide, N,N-dimethylpropionamide, N,N-diethylacetamide, and 1-butyl-2-pyrrolidone, wherein the amount of said solvent is 70% by mass or more of all solvents contained in the polyimide precursor composition.

4. The polyimide precursor composition of claim 1, wherein, The polyimide film obtained from the polyimide precursor composition has a light transmittance of over 70% at a wavelength of 400 nm when the film thickness is 10 µm.

5. The polyimide precursor composition of claim 1, wherein, The polyimide film obtained from the polyimide precursor composition has an elongation at break of 8% or more when the film thickness is 10 µm.

6. The polyimide precursor composition of claim 1, wherein, The polyimide film obtained from the polyimide precursor composition has a haze value of less than 1.0% when the film thickness is 10 µm.

7. The polyimide precursor composition of claim 1, wherein, When the polyimide precursor composition is stored at 23°C in an inert gas atmosphere immediately after manufacture, the polyimide precursor composition reaches its maximum viscosity within 4 days.

8. The polyimide precursor composition of claim 1, wherein, The polyimide film obtained from the polyimide precursor composition has a linear coefficient of thermal expansion of less than 20 ppm / K.

9. A polyimide film obtained from the polyimide precursor composition according to any one of claims 1 to 8.

10. A polyimide film / substrate laminate, comprising: Polyimide films obtained from the polyimide precursor compositions of any one of claims 1 to 8; and Support substrate.

11. The laminate of claim 10, wherein, The supporting substrate is a glass substrate.

12. A method for manufacturing a polyimide film / substrate laminate, comprising: (a) Applying the polyimide precursor composition of any one of claims 1 to 8 onto a support substrate; as well as (b) The polyimide precursor on the support substrate is heat-treated to form a laminate containing a polyimide film on the support substrate.

13. The method of claim 12, wherein, The supporting substrate is a glass substrate.

14. A method for manufacturing a flexible electronic device, comprising: (a) Applying the polyimide precursor composition of any one of claims 1 to 8 onto a support substrate; (b) The polyimide precursor on the support substrate is heat-treated to obtain a polyimide film / substrate laminate, wherein the polyimide film is laminated on the support substrate; (c) Forming at least one layer selected from conductor layers and semiconductor layers on the polyimide film of the laminate; and (d) Separate the supporting substrate from the polyimide film.

15. The method of claim 14, wherein, The supporting substrate is a glass substrate.

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