Polyimide precursor composition, polyimide film, and polyimide film / substrate laminate

Abstract

Provided is a polyimide precursor composition characterized by containing: a polyimide precursor in which a repeating unit is represented by general formula (I); and at least one imidazole compound contained in an amount within the range of 0.05-2 moles per 1 mole of repeating units of the polyimide precursor. The polyimide manufactured using the composition has the advantages of an aromatic polyimide film such as heat resistance and linear thermal expansion coefficient, and has improved light transmittance and improved adhesion in a polyimide film / substrate laminate. # imgabs0 (in the formula, 60-90 mol% of X1 is a structure represented by formula (1-1): # imgabs1 #, 10-40 mol% of X1 is at least one structure selected from the group consisting of structures represented by formula (1-2), formula (1-3), and formula (1-4): # imgabs2 #, and 70 mol% or more of Y1 is a structure represented by formula (B): # imgabs3 #.

Description

Technical Field

[0001] The present invention relates to a polyimide precursor composition, a polyimide film, and a polyimide film / substrate laminate which are suitable for use in electronic devices such as substrates of flexible devices. Background Art

[0002] Polyimide films are widely used in the fields of electrical / electronic devices, semiconductors, etc. due to their excellent heat resistance, chemical resistance, mechanical strength, electrical properties, dimensional stability, etc. On the other hand, in recent years, with the advent of a highly information-based society, the development of optical materials such as optical fibers and optical waveguides in the field of optical communications, and liquid crystal alignment films and protective films for color filters in the field of display devices is being promoted. In particular, in the field of display devices, as a substitute for glass substrates, research on lightweight and highly flexible plastic substrates and the development of displays that can be bent or curled are being actively carried out.

[0003] In displays such as liquid crystal displays and organic EL displays, semiconductor elements such as TFTs (thin film transistors) are formed to drive each pixel. Therefore, heat resistance and dimensional stability are required for the substrate. Polyimide films are expected to be used as substrates for display applications due to their excellent heat resistance, chemical resistance, mechanical strength, electrical properties, dimensional stability, etc.

[0004] Generally, it is difficult to maintain the planarity of a flexible film, and therefore it is difficult to uniformly and accurately form semiconductor elements such as TFTs, fine wiring, etc. on the flexible film. In order to solve this problem, for example, Patent Document 1 describes "a method for manufacturing a flexible device as a display device or a light receiving device, which includes the following steps: a step of applying a specific precursor resin composition to a carrier substrate and forming a film to form a solid polyimide resin film; a step of forming a circuit on the resin film; and a step of peeling the solid resin film with the circuit formed on the surface from the carrier substrate."

[0005] In addition, Patent Document 2 discloses a method for manufacturing a flexible device, which includes: after forming elements and circuits required for the device on a polyimide film / glass substrate laminate obtained by forming a polyimide film on a glass substrate, irradiating the glass substrate with laser from the glass substrate side to peel off the glass substrate.

[0006] In the methods for producing flexible electronic devices described in Patent Documents 1 and 2, in order to handle the polyimide film / glass substrate laminate, appropriate adhesion is required between the polyimide film and the glass substrate.

[0007] Polyimide is usually colored yellow-brown, so its use in transmissive devices such as liquid crystal displays with backlights is limited. However, in recent years, polyimide films that have excellent light transmittance in addition to mechanical and thermal properties have been developed, and expectations for them as substrates for display applications have further increased. For example, Patent Documents 4 to 6 describe semi-alicyclic polyimides that have excellent mechanical properties, heat resistance, etc. in addition to light transmittance.

[0008] As a countermeasure to reduce the coloration of polyimide, it is also proposed to introduce fluorine into the molecular structure. For example, Patent Document 7 discloses a mixture of a fluorinated aromatic diamine such as 2,2'-bis(trifluoromethyl)benzidine (TFMB) and trans-1,4-cyclohexyldiamine as a diamine component, and a mixture of aliphatic tetracarboxylic dianhydride and aromatic tetracarboxylic dianhydride as a tetracarboxylic acid component. In addition, Patent Document 8 records "a polyamic acid, wherein the diamine contains 2,2'-bis(trifluoromethyl)benzidine, the tetracarboxylic dianhydride contains 3,3',4,4'-biphenyltetracarboxylic dianhydride and 9,9'-(3,4'-dicarboxyphenyl)fluorene acid dianhydride, and the amount of 9,9'-(3,4'-dicarboxyphenyl)fluorene acid dianhydride is 0.5 mol% or more and 10 mol% or less relative to the total amount of tetracarboxylic anhydride".

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2010-202729

[0012] Patent Document 2: International Publication No. 2018 / 221607

[0013] Patent Document 4: International Publication No. 2012 / 011590

[0014] Patent Document 5: International Publication No. 2013 / 179727

[0015] Patent Document 6: International Publication No. 2014 / 038715

[0016] Patent Document 7: International Publication No. 2009 / 107429

[0017] Patent Document 8: International Publication No. 2019 / 188265 Summary of the invention

[0018] Problems to be solved by the invention

[0019] In recent years, the film formation method of TFT has been continuously improved. Compared with the past, the film formation temperature has been continuously lowered. However, high temperature processing is still required in certain processes. In addition, the greater the process margin, the better the yield. Therefore, it is preferred that the heat resistance of the substrate film is as high as possible. Aromatic polyimide has problems with coloring, but generally has excellent heat resistance. Therefore, if the coloring is reduced as much as possible, it may be used as a substrate for display purposes.

[0020] As described above, Patent Documents 7 and 8 disclose examples of using 2,2'-bis(trifluoromethyl)benzidine (TFMB), but the present inventors have conducted research and found the following problem: in the process of forming an electronic device from a polyimide film / glass substrate laminate using TFMB as a monomer component, the polyimide film is easily peeled off from the glass substrate. After an inorganic thin film having a gas barrier function is formed on the polyimide film / glass substrate laminate, peeling is easily caused when the laminate is exposed to high temperature.

[0021] Furthermore, the inventors have found during their research that the viscosity of the polyimide precursor solution prepared using TFMB as a monomer component changes greatly during storage, and there is a problem that it takes a long time for the viscosity to stabilize. Viscosity is related to coating performance and film thickness, so a stable viscosity is required as a product.

[0022] Therefore, an object of the present invention is to provide a polyimide precursor composition for producing a polyimide film having improved light transmittance and adhesion in a polyimide film / substrate laminate while taking advantage of the advantages of aromatic polyimide films such as heat resistance and linear thermal expansion coefficient. Furthermore, an object of the present invention is to provide a polyimide film and a polyimide film / substrate laminate obtained from the polyimide precursor.

[0023] Another object of one embodiment of the present invention is to provide a polyimide precursor composition having a more stable viscosity.

[0024] Means for solving problems

[0025] The main disclosed matters of this application are summarized as follows.

[0026] 1. A polyimide precursor composition, characterized in that it contains:

[0027] A polyimide precursor having a repeating unit represented by the following general formula (I); and

[0028] At least one imidazole compound is contained in an amount within a range of 0.05 mol to 2 mol per 1 mol of the repeating units of the polyimide precursor.

[0029] [Chemistry 1]

[0030]

[0031] (In the general formula (I), X1 is a tetravalent aliphatic group or aromatic group, Y1 is a divalent aliphatic group or aromatic group, R1 and R2 are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, wherein,

[0032] 60 mol% to 90 mol% of X1 is represented by formula (1-1):

[0033] [Chemistry 2]

[0034]

[0035] The structure shown in FIG. 1, wherein 10 to 40 mol % is selected from formula (1-2), formula (1-3) and formula (1-4):

[0036] [Chemistry 3]

[0037]

[0038] At least one of the structures shown,

[0039] 70 mol% or more of Y1 is of formula (B):

[0040] [Chemistry 4]

[0041]

[0042] The structure shown.)

[0043] 2. The polyimide precursor composition according to item 1 above, wherein 90 mol % or more of X1 is a structure selected from the group consisting of formula (1-1), formula (1-2), formula (1-3) and formula (1-4).

[0044] 3. The polyimide precursor composition according to item 1 or 2 above, wherein 90 mol % or more of Y1 is a structure represented by formula (B).

[0045] 4. The polyimide precursor composition according to item 1 above, wherein the imidazole compound is at least one selected from the group consisting of 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, and benzimidazole.

[0046] 5. A polyimide film obtained from the polyimide precursor composition according to any one of items 1 to 4 above.

[0047] 6. A polyimide film / substrate laminate, characterized in that it has:

[0048] A polyimide film obtained from the polyimide precursor composition described in any one of items 1 to 4 above; and

[0049] Base material.

[0050] 7. The laminate according to item 6 above, further comprising an inorganic thin film layer on the polyimide film of the laminate.

[0051] 8. The laminate according to item 6 or 7 above, wherein the peel strength between the polyimide film and the substrate is 20 gf / cm or more.

[0052] 9. The laminate according to any one of items 6 to 8 above, wherein the base material is a glass substrate.

[0053] 10. A method for producing a polyimide film / substrate laminate, comprising:

[0054] (a) a step of applying the polyimide precursor composition described in any one of items 1 to 4 above onto a substrate; and

[0055] (b) A step of heat-treating the polyimide precursor on the substrate to form a polyimide film on the substrate.

[0056] 11. The method for producing a laminate according to item 10 above, further comprising, after the step (b), a step (c) of forming an inorganic thin film layer on the polyimide film of the laminate.

[0057] 12. A method for manufacturing a flexible electronic device, comprising:

[0058] (d) a step of forming at least one layer selected from a conductor layer and a semiconductor layer on the inorganic thin film layer of the laminate produced in the above item 11; and

[0059] (e) A step of peeling the substrate and the polyimide film.

[0060] Effects of the Invention

[0061] According to the present invention, a polyimide precursor composition can be provided for producing a polyimide film having improved light transmittance and adhesion in a polyimide film / substrate laminate while taking advantage of the advantages of aromatic polyimide films such as heat resistance and linear thermal expansion coefficient. Furthermore, the present invention can provide a polyimide film obtained from the polyimide precursor and a polyimide film / substrate laminate.

[0062] Furthermore, according to one embodiment of the present invention, a polyimide precursor composition having a more stable viscosity can be provided.

[0063] Furthermore, according to one embodiment of the present invention, a polyimide film and a polyimide film / substrate laminate obtained using the polyimide precursor composition can be provided. Furthermore, according to another embodiment of the present invention, a method for producing a flexible electronic device using the polyimide precursor composition and a flexible electronic device can be provided. DETAILED DESCRIPTION

[0064] In the present application, "flexible (electronic) device" means that the device itself is flexible, and usually, a semiconductor layer (transistors, diodes, etc. as components) is formed on a substrate to complete the device. "Flexible (electronic) device" is different from existing devices such as COF (Chip On Film) that have "hard" semiconductor components such as IC chips mounted on FPC (flexible printed circuit board). However, in order to operate or control the "flexible (electronic) device" of the present application, there is no problem in mounting "hard" semiconductor components such as IC chips on a flexible substrate, or electrically connecting them, or fusing them for use. As preferred flexible (electronic) devices, there can be cited display devices such as liquid crystal displays, organic EL displays, and electronic paper, solar cells, and light receiving devices such as CMOS.

[0065] Hereinafter, the polyimide precursor composition of the present invention will be described, and then the method for producing a flexible electronic device will be described.

[0066] <<Polyimide Precursor Composition>>

[0067] The polyimide precursor composition for forming a polyimide film contains a polyimide precursor and an imidazole compound. In a preferred embodiment, the polyimide precursor composition further contains a solvent, and both the polyimide precursor and the imidazole compound are dissolved in the solvent.

[0068] The polyimide precursor has a repeating unit represented by the following general formula (I).

[0069] [Chemistry 5]

[0070]

[0071] (In the general formula (I), X1 is a tetravalent aliphatic group or aromatic group, Y1 is a divalent aliphatic group or aromatic group, and R1 and R2 are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0072] In particular, polyamic acid in which R1 and R2 are hydrogen atoms is preferred. When X1 and Y1 are aliphatic groups, the aliphatic group is preferably a group having an alicyclic structure.

[0073] In all the repeating units in the polyimide precursor, preferably 60 to 90 mol% of X1 has the structure represented by the following formula (1-1), that is, the structure derived from pyromellitic dianhydride (hereinafter, abbreviated as PMDA as needed).

[0074] [Chemical formula 6]

[0075]

[0076] In addition, preferably 10 to 40 mol% of X1 is selected from the following formulas (1-2), (1-3), and (1-4):

[0077] [Chemical formula 7]

[0078]

[0079] and at least one or more of the structures shown. They are structures derived from 4,4'-oxydiphthalic dianhydride (ODPA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA), and 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF).

[0080] By using a composition containing such a polyimide precursor, a polyimide film with improved light transmittance and adhesion in the polyimide film / substrate laminate can be manufactured. In addition, the obtained polyimide film is also excellent in properties such as heat resistance and low linear thermal expansion coefficient, which are the advantages of fully aromatic polyimide films.

[0081] Regarding the polyimide precursor, the monomers (tetracarboxylic acid component, diamine component, other components) that provide X1 and Y1 in the general formula (I) will be described, and then the manufacturing method will be described.

[0082] In this specification, the tetracarboxylic acid component includes tetracarboxylic acids, tetracarboxylic dianhydrides, and tetracarboxylic acid derivatives such as tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides used as raw materials for manufacturing polyimides. Although not particularly limited, it is convenient to use tetracarboxylic dianhydrides in manufacturing. In the following description, examples of using tetracarboxylic dianhydrides as the tetracarboxylic acid component will be described. In addition, the diamine component is a diamine compound having two amino groups (-NH2) used as a raw material for manufacturing polyimides.

[0083] In addition, in this specification, the polyimide film refers to both the film formed on the (carrier) substrate and present in the laminate, and the film after peeling off the substrate. In addition, the material obtained by heat-treating (imidizing) the material constituting the polyimide film, that is, the polyimide precursor composition, is sometimes referred to as "polyimide material".

[0084] <X1 and tetracarboxylic acid component>

[0085] As described above, X1 contains 60 mol% to 90 mol% of the structure of formula (1-1) (derived from PMDA), and 10 mol% to 40 mol% of at least one structure selected from the group consisting of the structure of formula (1-2) (derived from ODPA), the structure of formula (1-3) (derived from a-BPDA), and the structure of formula (1-4) (derived from BPAF).

[0086] In a preferred embodiment, the structure of formula (1-1) is present in a ratio of 70 mol % to 90 mol % in X1, which is preferred when a low linear thermal expansion coefficient is required.

[0087] The structures of formula (1-2), formula (1-3) and formula (1-4) may contain two or more. Among these structures, the structures of formula (1-2) and / or formula (1-3) are preferred, and the structures of formula (1-2) and / or formula (1-3) are also preferred to be in the range of 10 mol% to 40 mol%. The structure of formula (1-4) is preferably in an amount of 20 mol% or less, more preferably 10 mol% or less, and when included, it is preferably used in combination with the structures of formula (1-2) and / or formula (1-3).

[0088] In addition, the total of the structures represented by formula (1-1), formula (1-2), formula (1-3) and formula (1-4) is preferably 80 mol% or more of X1, more preferably 90 mol% or more, and even more preferably 95 mol% or more, and in a particularly preferred embodiment, it is 100 mol%.

[0089] In all the repeating units in the polyimide precursor, preferably 70 mol% or more of Y1, more preferably 80 mol% or more, further preferably 90 mol% or more, further more preferably 95 mol% or more, and in a particularly preferred embodiment 100 mol% is formula (B):

[0090] [Chemistry 8]

[0091]

[0092] The structure shown is the structure derived from 2,2'-bis(trifluoromethyl)benzidine (TFMB).

[0093] In the present invention, as X1, a tetravalent aliphatic group or aromatic group (referred to as "other X1") other than the structure shown in formula (1-1), formula (1-2), formula (1-3) and formula (1-4) can be contained in an amount that does not impair the effect of the present invention. As an aliphatic group, a tetravalent group having an alicyclic structure is preferred. Therefore, the tetracarboxylic acid component can contain "other tetracarboxylic acid derivatives" other than PMDA, ODPA, a-BPDA and BPAF in an amount of 30 mol% or less, more preferably 20 mol% or less, further more preferably 10 mol% or less, and further more preferably 5 mol% or less (0 mol% in a particularly preferred embodiment) relative to 100 mol% of the tetracarboxylic acid component.

[0094] As "other X1", a tetravalent group having an aromatic ring is preferred, and a tetravalent group having an aromatic ring having 6 to 40 carbon atoms is preferred. In particular, as "other X1", an aromatic group is preferred.

[0095] Examples of the tetravalent group having an aromatic ring include the following groups: However, groups corresponding to formulae (1-2) and (1-3) are excluded.

[0096] [Chemistry 9]

[0097]

[0098] (In the formula, Z1 is a direct bond or any of the following divalent groups.

[0099] [Chemistry 10]

[0100]

[0101] Wherein, Z2 in the formula is a divalent organic group, Z3 and Z4 are each independently an amide bond, an ester bond, or a carbonyl bond, and Z5 is an organic group containing an aromatic ring.

[0102] Specific examples of Z2 include an aliphatic hydrocarbon group having 2 to 24 carbon atoms and an aromatic hydrocarbon group having 6 to 24 carbon atoms.

[0103] Specific examples of Z5 include aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0104] As the tetravalent group having an aromatic ring, the following tetravalent groups are particularly preferred because the obtained polyimide film can achieve both high heat resistance and high light transmittance.

[0105] [Chemistry 11]

[0106]

[0107] (Wherein, Z1 is a direct bond or a hexafluoroisopropylidene bond.)

[0108] Here, Z1 is more preferably a direct bond because the obtained polyimide film can achieve high heat resistance, high light transmittance, and low linear thermal expansion coefficient.

[0109] In addition, as a preferred group, in the above formula (9), Z1 can be exemplified as the following formula (3A):

[0110] [Chemistry 12]

[0111]

[0112] The compound containing the fluorenyl group shown in the formula (1-4) is excluded. 11 and Z 12 Each of them is independently preferably the same and is a single bond or a divalent organic group. 11 and Z 12 , preferably an organic group containing an aromatic ring, preferably a structure represented by formula (3A1).

[0113] [Chemistry 13]

[0114]

[0115] (Z 13 and Z 14 are independently a single bond, -COO-, -OCO- or -O-, where Z 14 When it is bonded to a fluorenyl group, Z is preferably 13 is -COO-, -OCO- or -O- and Z 14 It is a single bond structure; R 91 is an alkyl group or a phenyl group having 1 to 4 carbon atoms, preferably a methyl group, and n is an integer of 0 to 4, preferably 1.

[0116] Examples of the tetracarboxylic acid component providing a repeating unit of the general formula (I) in which X1 is a tetravalent group 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, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 3,4'-oxydiphthalic acid, bis(3,4-dicarboxyphenyl)sulfone, m-terphenyl-3,4,3',4'-tetracarboxylic acid, p-terphenyl-3,4,3',4'-tetracarboxylic acid, dicarboxyphenyldimethylsilane, bisdicarboxyphenoxydiphenyl sulfide, sulfonyldiphthalic acid, and derivatives thereof such as tetracarboxylic dianhydrides, tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides. As a tetracarboxylic acid component providing a repeating unit of the general formula (I) in which X1 is a tetravalent group having an aromatic ring containing a fluorine atom, for example, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, its tetracarboxylic dianhydride, tetracarboxylic acid silyl ester, tetracarboxylic acid ester, tetracarboxylic acid chloride and other derivatives can be cited. In addition, as a preferred compound, (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) can be cited. The tetracarboxylic acid component can be used alone or in combination of two or more.

[0117] As the tetracarboxylic acid component for providing the repeating unit of the formula (I) in which X1 is a tetravalent group having an alicyclic structure, for example, 1,2,3,4-cyclobutanetetracarboxylic acid, isopropylidenediphenoxy bisphthalic acid, cyclohexane-1,2,4,5-tetracarboxylic acid, [1,1'-bi(cyclohexane)]-3,3',4,4'-tetracarboxylic acid, [1,1'-bi(cyclohexane)]-2,3,3',4'-tetracarboxylic acid, [1,1'-bi(cyclohexane)]-2,2',3,3'-tetracarboxylic acid, 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic acid), 4,4'-thiobis(cyclohexane-1,2-dicarboxylic acid), 4,4'-sulfonylbis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), octahydrobicyclopentadiene-1,3,4,6-tetracarboxylic acid, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid, 6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3,5-tricarboxylic acid, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2.2.2]oct-5-ene-2,3,7,8-tetracarboxylic acid, tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid, tricyclo[4.2.2.02,5]dec-7-ene-3,4,9,10-tetracarboxylic acid, 9-oxatricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane 5,5”,6,6”-tetracarboxylic acid, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic acid, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic acid, decahydro-1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, and their derivatives such as tetracarboxylic dianhydrides, tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarbonyl chlorides can be mentioned. The tetracarboxylic acid component can be used alone, or two or more of them can be used in combination.

[0118] <Y1 and diamine component>

[0119] As described above, Y1 contains the structure derived from 2,2'-bis(trifluoromethyl)benzidine (TFMB) in an amount of 70 mol% or more, and the preferred amount is as described above.

[0120] In the present invention, as Y1, a divalent aliphatic group or aromatic group other than the structure represented by formula (B) (hereinafter referred to as "other Y1") may be contained in an amount within a range that does not impair the effect of the present invention. That is, in addition to TFMB, the diamine component may contain other diamine compounds in an amount of 30 mol% or less, more preferably 20 mol% or less, further more preferably 10 mol% or less, further more preferably 5 mol% or less (0 mol% in a particularly preferred embodiment) relative to 100 mol% of the diamine component.

[0121] When "other Y1" is a divalent group having an aromatic ring, it is preferably a divalent group having 6 to 40 carbon atoms, more preferably a divalent group having 6 to 20 carbon atoms.

[0122] Examples of the divalent group having an aromatic ring include the following groups.

[0123] [Chemistry 14]

[0124]

[0125] (W1 is a direct bond or a divalent organic group, n 11 ~n 13 Each independently represents an integer from 0 to 4, R 51 , R 52 , R 53 Each is independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group.)

[0126] Specific examples of W1 include a direct bond, a divalent group represented by the following formula (5), and a divalent group represented by the following formula (6).

[0127] [Chemistry 15]

[0128]

[0129] [Chemistry 16]

[0130]

[0131] (R in formula (6) 61 ~R 68 Each independently represents a direct bond or any one of the divalent groups represented by the above formula (5).

[0132] Here, since the obtained polyimide can take into account high heat resistance, high transparency, and low linear thermal expansion coefficient, W1 is particularly preferably a direct bond or one selected from the group consisting of groups represented by the formula: -NHCO-, -CONH-, -COO-, and -OCO-. In addition, W1 is also particularly preferably R 61 ~R68 It is any one of the divalent groups represented by the above formula (6) which is a direct bond or one selected from the group consisting of groups represented by the formulas: -NHCO-, -CONH-, -COO-, and -OCO-.

[0133] In addition, as a preferred group, in the above formula (4), W1 can be exemplified as the following formula (3B):

[0134] [Chemistry 17]

[0135]

[0136] The compound containing the fluorenyl group shown. 11 and Z 12 Each of them is independently preferably the same and is a single bond or a divalent organic group. 11 and Z 12 , preferably an organic group containing an aromatic ring, preferably a structure represented by formula (3B1).

[0137] [Chemistry 18]

[0138]

[0139] (Z 13 and Z 14 Each independently represents a single bond, -COO-, -OCO- or -O-, where Z 14 When it is bonded to a fluorenyl group, Z is preferably 13 is -COO-, -OCO- or -O- and Z 14 It is a single bond structure; R 91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably a phenyl group, and n is an integer of 0 to 4, preferably 1. )

[0140] As other preferred groups, in the above formula (4), compounds in which W1 is a phenylene group, that is, terphenylenediamine compounds can be mentioned, and compounds in which all of them are para-bonded are particularly preferred.

[0141] As other preferred groups, in the above formula (4), W1 can be exemplified as R in the structure where the first phenyl ring of formula (6) is 61 and R 62 A 2,2-propylene compound.

[0142] As another preferred group, in the above formula (4), there can be mentioned a compound where W1 is represented by the following formula (3B2).

[0143] [Chemistry 19]

[0144]

[0145] Examples of the diamine component that provides Y1 as a divalent group having an aromatic ring include p-phenylenediamine, m-phenylenediamine, benzidine, 3,3'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)benzidine, m-tolidine, 3,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)terephthalamide, N,N'-p-phenylenebis(p-aminobenzamide), 4-aminophenoxy-4-diaminobenzoate, bis(4-aminophenyl)terephthalate, biphenyl-4,4'-dicarboxylic acid bis(4 -aminophenyl) ester, p-phenylene bis(p-aminobenzoate), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylate, [1,1'-biphenyl]-4,4'-diylbis(4-aminobenzoate), 4,4'-oxydiphenylamine, 3,4'-oxydiphenylamine, 3,3'-oxydiphenylamine, 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)benzene, 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)diphenyl)sulfone, bis(4-(3-aminophenoxy)diphenyl)sulfone, octafluorobiphenyl amine, 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, 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine. Examples of the diamine component providing a repeating unit of the general formula (I) in which Y1 is a divalent group having 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.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 may be used alone or in combination of two or more.

[0146] When "other Y1" is a divalent group having an alicyclic structure, it is preferably a divalent group having an alicyclic structure having 4 to 40 carbon atoms, more preferably having at least one aliphatic 4- to 12-membered ring, and more preferably an aliphatic 6-membered ring.

[0147] Examples of the divalent group having an alicyclic structure include the following groups.

[0148] [Chemistry 20]

[0149]

[0150] (wherein, V1 and V2 are each independently a direct bond or a divalent organic group, n 21 ~n 26 Each independently represents an integer from 0 to 4, R 81 ~R 86 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, R 91 , R 92 , R 93 Each is independently selected from the group consisting of groups represented by the formula: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-.)

[0151] Specific examples of V1 and V2 include a direct bond and a divalent group represented by the above formula (5).

[0152] Examples of the diamine component that provides Y1 as a divalent group 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-diaminocyclobutane. , 1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, diaminobicycloheptane, diaminomethylbicycloheptane, diaminooxybicycloheptane, diaminomethoxybicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane. The diamine components may be used alone or in combination of two or more.

[0153] As the tetracarboxylic acid component and the diamine component providing the repeating unit represented by the general formula (I), any of aliphatic tetracarboxylic acids other than alicyclic ones (particularly dianhydrides) and / or aliphatic diamines can be used, and the content thereof is preferably less than 30 mol%, more preferably less than 20 mol%, and further preferably less than 10 mol% (including 0%) relative to 100 mol% of the total of the tetracarboxylic acid component and the diamine component.

[0154] By including a structure represented by formula (3B) as "other Y1" or a diamine compound such as 9,9-bis(4-aminophenyl)fluorene as a specific compound, Tg may be increased and the phase difference (retardation) in the film thickness direction may be reduced.

[0155] The polyimide precursor can be prepared from the above-mentioned tetracarboxylic acid component and diamine component. According to the chemical structure taken by R1 and R2, the polyimide precursor used in the present invention (including at least one of the repeating units represented by the above formula (I)) can be classified as follows:

[0156] 1) Polyamic acid (R1 and R2 are hydrogen);

[0157] 2) polyamic acid ester (at least a part of R1 and R2 is an alkyl group);

[0158] 3) 4) Polyamic acid silyl ester (at least a part of R1 and R2 is an alkylsilyl group).

[0159] And the polyimide precursor can be easily produced by the following production method according to this classification. However, the production method of the polyimide precursor used in the present invention is not limited to the following production method.

[0160] 1) Polyamic acid

[0161] The polyimide precursor can be suitably obtained as a polyimide precursor solution by the following reaction: tetracarboxylic dianhydride and diamine component as tetracarboxylic acid components are reacted in a solvent in approximately equimolar ratios, preferably in a ratio where the molar ratio of the diamine component to the tetracarboxylic acid component [the number of moles of the diamine component / the number of moles of the tetracarboxylic acid component] is preferably 0.90 to 1.10, more preferably 0.95 to 1.05, at a relatively low temperature of, for example, 120° C. or less while suppressing imidization.

[0162] There is no limitation, more specifically, diamine is dissolved in an organic solvent or water, tetracarboxylic dianhydride is slowly added to the solution while stirring, and stirred in the range of 0 to 120°C, preferably 5°C to 80°C for 1 hour to 72 hours, thereby obtaining a polyimide precursor. In the case of reaction above 80°C, the molecular weight varies depending on the temperature history during polymerization, and imidization is performed by heat, so it may not be possible to stably produce a polyimide precursor. The order of addition of diamine and tetracarboxylic dianhydride in the above-mentioned production method is easy to increase the molecular weight of the polyimide precursor, so it is preferred. In addition, the order of addition of diamine and tetracarboxylic dianhydride in the above-mentioned production method can also be reversed, which is preferred because the precipitate is reduced. When water is used as a solvent, it is preferred to add imidazoles such as 1,2-dimethylimidazole or bases such as triethylamine in an amount of 0.8 times or more of the carboxyl group of the generated polyamic acid (polyimide precursor).

[0163] 2) Polyamic acid ester

[0164] Tetracarboxylic dianhydride is reacted with any alcohol to obtain a dicarboxylic acid diester, which is then reacted with a chlorinating agent (thionyl chloride, oxalyl chloride, etc.) to obtain a diester dicarboxylic acid chloride. The diester dicarboxylic acid chloride and diamine are stirred at -20°C to 120°C, preferably in the range of -5°C to 80°C for 1 hour to 72 hours to obtain a polyimide precursor. In the case of a reaction above 80°C, the molecular weight varies depending on the temperature history during polymerization, and imidization is performed by heat, so it may not be possible to stably manufacture a polyimide precursor. In addition, a polyimide precursor can also be easily obtained by dehydrating and condensing a dicarboxylic acid diester and a diamine using a phosphorus-based condensing agent, a carbodiimide condensing agent, etc.

[0165] Since the polyimide precursor obtained by this method is stable, it can also be purified by adding a solvent such as water or alcohol and performing reprecipitation.

[0166] 3) Polyamic acid silyl ester (indirect method)

[0167] A diamine is reacted with a silylating agent in advance to obtain a silylated diamine. The silylated diamine is purified by distillation or the like as needed. Then, the silylated diamine is dissolved in a dehydrated solvent in advance, tetracarboxylic dianhydride is slowly added while stirring, and stirred at 0 to 120°C, preferably in the range of 5°C to 80°C for 1 hour to 72 hours, thereby obtaining a polyimide precursor. In the case of a reaction above 80°C, the molecular weight varies depending on the temperature history during polymerization, and imidization is carried out by heat, so it may not be possible to stably produce a polyimide precursor.

[0168] 4) Polyamic acid silyl ester (direct method)

[0169] The polyamic acid solution obtained in the method 1) is mixed with a silylating agent and stirred at 0 to 120° C., preferably in the range of 5 to 80° C., for 1 to 72 hours to obtain a polyimide precursor. When reacting at 80° C. or higher, the molecular weight varies depending on the temperature history during polymerization, and imidization proceeds by heat, so there is a possibility that the polyimide precursor cannot be stably produced.

[0170] As the silylating agent used in the method 3) and the method 4), when a silylating agent that does not contain chlorine is used, it is not necessary to purify the silylated polyamic acid or the obtained polyimide, so it is preferred. As the silylating agent that does not contain chlorine atoms, N, O-bis (trimethylsilyl) trifluoroacetamide, N, O-bis (trimethylsilyl) acetamide, and hexamethyldisilazane can be cited. Because it does not contain fluorine atoms and has low cost, N, O-bis (trimethylsilyl) acetamide and hexamethyldisilazane are particularly preferred.

[0171] In the silylation reaction of diamine in the method 3), an amine catalyst such as pyridine, piperidine, triethylamine, etc. may be used to promote the reaction. The catalyst may be used directly as a polymerization catalyst for the polyimide precursor.

[0172] The solvent used in preparing the polyimide precursor is preferably water, or a non-protonic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, etc. Any type of solvent can be used without problem as long as it can dissolve the raw monomer components and the generated polyimide precursor, so there is no particular limitation on its structure. As the solvent, it is preferred to use 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, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, cyclopentane, dimethyl sulfoxide, and the like. In addition, other common organic solvents may be used, i.e., phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, 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 spirits, naphtha-based solvents, etc. It should be noted that two or more solvents may be used in combination.

[0173] In the production of the polyimide precursor, there are no particular restrictions, and a monomer and a solvent are added so that the solid content concentration of the polyimide precursor (polyimide-converted mass concentration) is, for example, 5% by mass to 45% by mass to carry out the reaction.

[0174] The logarithmic viscosity of the polyimide precursor is not particularly limited, but preferably the logarithmic viscosity in a 0.5 g / dL N-methyl-2-pyrrolidone solution at 30° C. is 0.2 dL / g or more, more preferably 0.3 dL / g or more, and particularly preferably 0.4 dL / g or more. When the logarithmic viscosity is 0.2 dL / g or more, the molecular weight of the polyimide precursor is high, and the obtained polyimide has excellent mechanical strength and heat resistance.

[0175] <Imidazole compounds>

[0176] The polyimide precursor composition contains at least one imidazole compound. The imidazole compound is not particularly limited as long as it is a compound having an imidazole skeleton, and examples thereof include 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, and benzimidazole. A plurality of imidazole compounds may be used in combination.

[0177] The content of the imidazole compound in the polyimide precursor composition can be appropriately selected in consideration of the balance between the addition effect and the stability of the polyimide precursor composition. The amount (total content) of the imidazole compound is preferably in the range of 0.05 mol to 2 mol relative to 1 mol of the repeating unit of the polyimide precursor. The addition of the imidazole compound has an effect on improving the adhesion between the polyimide film and the substrate in the polyimide film / substrate laminate (increasing the peel strength), and also has an effect on improving the transmittance. Furthermore, a decreasing trend of the linear thermal expansion coefficient is also observed.

[0178] In addition, it is known that in the monomer composition of the present invention, adding an appropriate amount of imidazole compounds is effective for the viscosity stability of the polyimide precursor composition. The viscosity of the polyimide precursor solution with the same monomer composition as the present invention rises slowly without adding imidazole compounds or in a small amount, and requires a long time until reaching the maximum value. On the other hand, when the amount of imidazole compounds is excessive, the viscosity decreases sharply after reaching the maximum value. In contrast, if imidazole compounds are added within the scope of the present invention, the period of reaching the viscosity maximum is shortened, and the viscosity reduction thereafter is slow, so the period with the appropriate viscosity range is long, and a practically applicable polyimide precursor composition can be obtained.

[0179] On the other hand, in a monomer composition different from the present invention, there is almost no difference in the period during which the viscosity reaches the maximum value depending on whether the imidazole compound is added. Therefore, the problem of the viscosity stable period is understood to be a problem unique to the monomer composition of the present invention.

[0180] The content of the imidazole compound is more preferably 0.08 mol or more, still more preferably 0.1 mol or more, still more preferably 0.4 mol or more, and is more preferably 1.8 mol or less, still more preferably 1.5 mol or less, based on 1 mol of the repeating unit.

[0181] <Mixing of Polyimide Precursor Composition>

[0182] The polyimide precursor composition used in the present invention contains at least one polyimide precursor, at least one imidazole compound described above, and preferably a solvent.

[0183] As a solvent, the above-mentioned solvent described as a solvent used in preparing a polyimide precursor can be used. Usually, the solvent used in preparing a polyimide precursor can be used directly, that is, in the state of a polyimide precursor solution, but it can also be diluted or concentrated and used as needed. The imidazole compound is dissolved and present in the polyimide precursor composition. There is no particular limitation on the concentration of the polyimide precursor, and it is usually 5% to 45% by mass in terms of polyimide conversion mass concentration (solid content concentration). Here, the polyimide conversion mass refers to the mass when all repeating units are completely imidized.

[0184] The viscosity (rotational viscosity) of the polyimide precursor composition of the present invention is not particularly limited, and is measured using an E-type rotational viscometer at a temperature of 25° C. and a shear rate of 20 seconds. -1 The rotational viscosity measured under the conditions of is preferably 0.01 Pa·second to 1000 Pa·second, more preferably 0.1 Pa·second to 100 Pa·second. In addition, thixotropy can be imparted as required. At the viscosity within the above range, it is easy to handle during coating or film formation, and shrinkage cavities are suppressed and leveling properties are excellent, so a good coating can be obtained.

[0185] The polyimide precursor composition of the present invention may contain a chemical imidizing agent (acid anhydrides such as acetic anhydride, amine compounds such as pyridine and isoquinoline), an antioxidant, an ultraviolet absorber, a filler (inorganic particles such as silica, etc.), a dye, a pigment, a coupling agent such as a silane coupling agent, a primer, a flame retardant, a defoaming agent, a leveling agent, a rheology control agent (flow aid), etc. as needed.

[0186] The polyimide precursor composition can be prepared by adding an imidazole compound or a solution of an imidazole compound to the polyimide precursor solution obtained by the above method and mixing them. The tetracarboxylic acid component and the diamine component can be reacted in the presence of the imidazole compound.

[0187] <<Manufacturing of polyimide film / substrate laminate and flexible electronic device>>

[0188] The polyimide precursor composition of the present invention can be used to manufacture a polyimide film / substrate laminate. The polyimide film / substrate laminate can be manufactured by the following steps: (a) a step of applying the polyimide precursor composition to a substrate; (b) heat-treating the polyimide precursor on the substrate to manufacture a laminate (polyimide film / substrate laminate) having a polyimide film laminated on the substrate. In addition, after forming the polyimide film on the substrate, it is also preferred to further have a step of forming an inorganic thin film on the surface of the polyimide film as step (b2).

[0189] The method for manufacturing a flexible electronic device of the present invention uses a polyimide film / substrate laminate manufactured by the above-mentioned steps (a) and (b) (preferably a further step (b2)), and further comprises the following steps: (c) a step of forming at least one layer selected from a conductor layer and a semiconductor layer on the polyimide film of the above-mentioned laminate; and (d) a step of peeling the above-mentioned substrate from the above-mentioned polyimide film.

[0190] First, in step (a), a polyimide precursor composition is cast on a substrate, and imidization and solvent removal are performed by heat treatment to form a polyimide film, thereby obtaining a laminate of the substrate and the polyimide film (polyimide film / substrate laminate).

[0191] As the substrate, a heat-resistant material is used, for example, a plate-like or sheet-like substrate of a ceramic material (glass, alumina, etc.), a metal material (iron, stainless steel, copper, aluminum, etc.), a semiconductor material (silicon, compound semiconductor, etc.), or a film or sheet-like substrate of a heat-resistant plastic material (polyimide, etc.). Generally, a flat and smooth plate is preferred, and generally, a glass substrate of soda-lime glass, borosilicate glass, alkali-free glass, sapphire glass, etc.; a semiconductor substrate (including compound semiconductor) of silicon, GaAs, InP, GaN, etc.; a metal substrate of iron, stainless steel, copper, aluminum, etc. is used.

[0192] As the substrate, a glass substrate is particularly preferred. Flat, smooth and large-area glass substrates have been developed and can be easily obtained. There is no limitation on the thickness of plate-like substrates such as glass substrates. From the perspective of ease of handling, it is, for example, 20 μm to 4 mm, preferably 100 μm to 2 mm. In addition, there is no particular limitation on the size of the plate-like substrate. One side (the long side in the case of a rectangle) is, for example, about 100 mm to about 4000 mm, preferably about 200 mm to about 3000 mm, and more preferably about 300 mm to about 2500 mm.

[0193] These glass substrates and other base materials may have an inorganic thin film (eg, a silicon oxide film) or a resin thin film formed on the surface.

[0194] The method for casting the polyimide precursor composition on the substrate is not particularly limited, and examples thereof include slit coating, die coating, blade coating, spray coating, inkjet coating, nozzle coating, spin coating, screen printing, rod coating, electrodeposition and the like.

[0195] In step (b), the polyimide precursor composition is heat-treated on the substrate to convert it into a polyimide film, thereby obtaining a polyimide film / substrate laminate. The heat treatment conditions are not particularly limited, but it is preferably dried at a temperature range of 50°C to 150°C, and then treated 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.

[0196] The thickness of the polyimide film is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 5 μm or more. When the thickness is less than 1 μm, the polyimide film cannot maintain sufficient mechanical strength. For example, when used as a substrate for a flexible electronic device, it is sometimes unable to fully withstand stress and is damaged. In addition, the thickness of the polyimide film is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 20 μm or less. If the thickness of the polyimide film becomes thicker, it sometimes becomes difficult to thin the flexible device. In order to maintain sufficient tolerance as a flexible device and further thin the film, the thickness of the polyimide film is preferably 2 μm to 50 μm.

[0197] In the present invention, the polyimide film / substrate laminate preferably has a small warp. The details of the measurement are described in Japanese Patent Gazette No. 6798633. In one embodiment, when the residual stress between the polyimide film and the silicon substrate in the polyimide film / silicon substrate (wafer) laminate is used to evaluate the properties of the polyimide film, the residual stress is preferably less than 27 MPa. The polyimide film is placed at 23° C. in a dry state.

[0198] The polyimide film in the polyimide film / substrate laminate may also have a second layer such as an inorganic thin film on the surface. Therefore, as step (b2), it is preferred to have a step of forming an inorganic thin film on the surface of the polyimide film formed on the substrate. The inorganic thin film is particularly preferred to function as a barrier layer for water vapor or oxygen (air). As the water vapor barrier layer, for example, a layer selected from silicon nitride (SiN x ), silicon oxide (SiO x ), silicon oxynitride (SiO x N y), aluminum oxide (Al2O3), titanium oxide (TiO2), zirconium oxide (ZrO2) and other metal oxides, metal nitrides and metal oxynitrides. In general, known methods for forming these thin films include physical vapor deposition methods such as vacuum evaporation, sputtering, and ion plating, and chemical vapor deposition methods (CVD: chemical vapor deposition) such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD). In these film formation methods including the CVD method, in order to improve the barrier function, after the film is formed, high-temperature annealing is performed at, for example, 350°C to 450°C to densify the film. It should be noted that in the present application, "inorganic thin film" refers to two states before and after annealing. When only one is indicated, it is explicitly indicated or made clear according to the context. Similarly, "polyimide film / substrate laminate" refers to both having and not having an "inorganic thin film".

[0199] The second layer may also be a plurality of layers. In this case, different types of inorganic thin films may be formed, and resin films and inorganic thin films may be composited. As an example of the latter, a three-layer structure of barrier layer / polyimide layer / barrier layer may be formed on the polyimide film in a polyimide film / substrate laminate.

[0200] In step (c), at least one layer selected from a conductor layer and a semiconductor layer is formed on the polyimide film (including the case where a second layer such as an inorganic thin film is laminated on the surface of the polyimide film) using the polyimide / substrate laminate obtained in step (b). These layers may be formed directly on the polyimide film (including the case where the second layer is laminated), or may be formed indirectly after laminating other layers required for the device.

[0201] The conductor layer and / or semiconductor layer are selected appropriately according to the elements and circuits required by the target electronic device. In step (c) of the present invention, when at least one of the conductor layer and the semiconductor layer is formed, it is also preferred to form at least one of the conductor layer and the semiconductor layer on a polyimide film formed with an inorganic film.

[0202] The conductor layer and the semiconductor layer include both the case where they are formed on the entire surface of the polyimide film and the case where they are formed on a portion of the polyimide film. The present invention may be transferred to step (d) immediately after step (c), or may be transferred to step (d) after forming at least one layer selected from the conductor layer and the semiconductor layer in step (c), further forming a device structure, and then transferring to step (d).

[0203] In the case of manufacturing a TFT liquid crystal display device as a flexible device, for example, metal wiring, TFT using amorphous silicon or polycrystalline silicon, and transparent pixel electrodes are formed on a polyimide film having an inorganic film formed on the entire surface as required. The TFT includes, for example, a semiconductor layer such as a gate metal layer, an amorphous silicon film, a gate insulating layer, wiring connected to the pixel electrode, etc. In addition, the structure required for the liquid crystal display can be further formed by a known method. In addition, a transparent electrode and a color filter can also be formed on the polyimide film.

[0204] When manufacturing an organic EL display, for example, TFTs may be formed as needed on a polyimide film having an inorganic film formed on the entire surface in addition to transparent electrodes, a light-emitting layer, a hole transport layer, an electron transport layer, etc.

[0205] The polyimide film preferred in the present invention is excellent in various properties such as heat resistance and toughness, and therefore the method of forming circuits, elements, and other structures required for the device is not particularly limited.

[0206] Next, in step (d), the substrate and the polyimide film are peeled off. The peeling method may be a mechanical peeling method in which an external force is applied to physically peel the substrate, but the polyimide film / substrate laminate of the present invention has excellent adhesion, so it is particularly preferred to peel the substrate by irradiating a laser from the substrate surface to perform the peeling.

[0207] The structure or components required for the device are further formed or assembled on the (semi-)product using the polyimide film after the substrate is peeled off as a substrate to complete the device.

[0208] It should be noted that as another method for manufacturing flexible electronic devices, after manufacturing the polyimide film / substrate laminate through the above-mentioned step (b), the polyimide film can be peeled off, and at least one layer selected from a conductor layer and a semiconductor layer and the necessary structure can be formed on the polyimide film as in the above-mentioned step (c), to manufacture a (semi) product using the polyimide film as a substrate.

[0209] <<Polyimide Film Properties in Polyimide Film / Base Laminate>>

[0210] When the polyimide film / substrate laminate as described above is produced from the polyimide precursor composition of the present invention, the polyimide film and the substrate have excellent adhesion, and therefore the laminate is particularly preferably used for such an application.

[0211] The polyimide film produced from the polyimide precursor composition of the present invention is excellent in light transmittance, thermal properties, and heat resistance, as well as adhesion to a substrate such as a glass substrate.

[0212] Adhesion can be evaluated by peel strength. The peel strength between the polyimide film and the substrate in the polyimide film / substrate laminate is measured according to JIS K6854-1, for example, in a tensile speed of 2mm / minute, a 90° peel test, preferably more than 20gf / cm (0.196N / cm), more preferably more than 22gf / cm (0.216N / cm). In addition, as an upper limit, it is usually less than 1kgf / cm, preferably less than 800gf / cm. Peel strength is usually measured in air or in the atmosphere.

[0213] It is known that: in the case of the monomer composition of the present invention, the adhesion is poor (the peel strength is small), but the peel strength is improved by adding the imidazole compound. On the other hand, in the case of the composition with the alicyclic monomer as the main component as the tetracarboxylic acid component, there is no problem of poor adhesion (small peel strength), but if the imidazole compound is added, the peel strength is reduced. In addition, even if the tetracarboxylic acid component is an aromatic system, if the composition is outside the scope of the present invention, it is observed that the peel strength is not improved even if the imidazole compound is added.

[0214] In one embodiment of the present invention, when measured using a film with a thickness of 10 μm, the 450 nm light transmittance of the polyimide film is preferably 80% or more, more preferably 81% or more, and even more preferably 83% or more. In addition, when measured using a film with a thickness of 10 μm, the yellowness (YI) of the polyimide film is preferably 9.0 or less, more preferably 8.5 or less, even more preferably 8.0 or less, even more preferably 7.5 or less, even more preferably 7.0 or less, and most preferably 6.0 or less.

[0215] The polyimide film of the present invention has an extremely low linear thermal expansion coefficient. In one embodiment of the present invention, when measured using a film with a thickness of 10 μm, the linear thermal expansion coefficient (CTE) of the polyimide film from 150° C. to 250° C. is preferably 25 ppm / K or less, more preferably 20 ppm / K or less, further more preferably less than 20 ppm, further more preferably 15 ppm / K or less, further more preferably 11 ppm / K or less, and most preferably 10 ppm / K or less.

[0216] The polyimide film of the present invention (or the polyimide constituting the polyimide) is excellent in heat resistance, and the 1% weight loss temperature is preferably 520° C. or higher, more preferably 530° C. or higher, and even more preferably 540° C. or higher.

[0217] In one embodiment of the present invention, the glass transition temperature (Tg) of the polyimide film (or the polyimide constituting the polyimide) is preferably above 350°C, more preferably above 370°C, further more preferably above 390°C, further more preferably above 400°C, further more preferably above 410°C, further more preferably above 420°C, further more preferably above 430°C, further more preferably above 435°C, and most preferably above 440°C.

[0218] Furthermore, in one embodiment of the present invention, the elongation at break of the polyimide film is preferably 4% or more, more preferably 7% or more, when measured using a film having a thickness of 10 μm.

[0219] In another preferred embodiment of the present invention, the breaking strength of the polyimide film is preferably 150 MPa or more, more preferably 170 MPa or more, further preferably 180 MPa or more, further preferably 200 MPa or more, further preferably 210 MPa or more. The breaking strength can be, for example, a value obtained from a film having a thickness of about 5 μm to 100 μm.

[0220] Of the above-mentioned preferred properties of the polyimide film, it is particularly preferred that the adhesion, light transmittance, linear thermal expansion coefficient, and 1% weight loss temperature are satisfied simultaneously.

[0221] The polyimide precursor composition of the present invention can also be used to manufacture other types of polyimide and a separate polyimide film. The manufacturing method is not particularly limited, and known imidization methods can be suitably used. The form of the obtained polyimide can suitably include a film, a coating film, a powder, a bead, a molded body, a foam, etc.

[0222] A separate polyimide film can be manufactured using a known method. A representative method is the following method: a polyimide precursor composition is cast onto a substrate, and then, the substrate is heated and imidized, and then the polyimide film is peeled off. Alternatively, the polyimide precursor composition may be cast onto a substrate, and then heated and dried to produce a self-supporting film, and then the self-supporting film is peeled off from the substrate, for example, by holding the film with a tenter, and heating and imidizing in a state where degassing can be performed from both sides of the film to obtain a polyimide film.

[0223] The thickness of the polyimide film alone also depends on the application, but is preferably 1 μm or more, more preferably 2 μm or more, further preferably 5 μm or more, for example 250 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and further preferably 50 μm or less.

[0224] Example

[0225] The present invention is further described below by way of examples and comparative examples. It should be noted that the present invention is not limited to the following examples.

[0226] In the following examples, the evaluation was performed by the following method.

[0227] <Evaluation of Polyimide Precursor Composition>

[0228] [Viscosity stabilization and maximum viscosity rate retention evaluation]

[0229] After polymerization, when the polyimide precursor composition is stored at 23°C, the viscosity increases, reaches the maximum viscosity and then decreases. When the maximum viscosity is reached, it is evaluated as "viscosity stabilization". The viscosity stabilization days of the polyimide precursor composition having the monomer composition and the amount of imidazole compound added described in Table 8 were evaluated. In addition, although the viscosity decreases after reaching the maximum viscosity, the ratio of the viscosity 14 days after the day when the maximum viscosity is reached to the maximum viscosity is taken as the "maximum viscosity retention rate", and the case with a viscosity of 50% or more relative to the maximum viscosity is evaluated as "0", and the case with a viscosity of less than 50% is evaluated as "×".

[0230] In addition, the viscosity was measured using an E-type viscometer TVE-25 manufactured by Toki Sangyo Co., Ltd. at a measurement temperature of 25°C.

[0231] <Evaluation of polyimide film>

[0232] [450nm transmittance]

[0233] In Examples and Comparative Examples, the transmittance at 450 nm was measured using a UV-visible spectrophotometer / V-650DS (manufactured by JASCO Corporation) for polyimide films having a thickness of about 10 μm when the film thickness was not described and for polyimide films having the described film thickness when the film thickness was described.

[0234] [Coefficient of linear thermal expansion (CTE)]

[0235] A polyimide film with a film thickness of about 10 μm was cut into strips with a width of 4 mm to prepare test pieces, and the temperature was cooled from 400°C to 50°C using TMA / SS6100 (manufactured by SII Nanotechnology Co., Ltd.) under the conditions of a chuck length of 15 mm, a load of 2 g, and a cooling rate of 20°C / min. The linear thermal expansion coefficient from 150°C to 250°C was obtained from the obtained TMA curve.

[0236] [1% weight loss temperature, 5% weight loss temperature]

[0237] A polyimide film having a film thickness of about 10 μm was used as a test piece, and the temperature was raised from 25° C. to 600° C. at a heating rate of 10° C. / min in a nitrogen flow using a calorimeter measuring device (Q5000IR) manufactured by TAINSTRUMENTS. From the obtained weight curve, the weight at 150° C. was set as 100%, and the 1% weight loss temperature and the 5% weight loss temperature were determined.

[0238] [Peel strength]

[0239] The peel strength in the 90° direction was measured in the atmosphere at a tensile speed of 2 mm / min using TENSILON RTA-500 manufactured by ORIENTEC.

[0240] <Raw materials>

[0241] The abbreviations, purity, etc. of the raw materials used in the following examples are as follows.

[0242] [Tetracarboxylic acid component]

[0243] PMDA: pyromellitic dianhydride

[0244] a-BPDA: 2,3,3',4'-biphenyltetracarboxylic dianhydride

[0245] ODPA: 4,4'-oxydiphthalic anhydride

[0246] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride

[0247] s-BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

[0248] 6FDA: 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride

[0249] CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

[0250] HPMDA: Cyclohexane-1,2,4,5-tetracarboxylic dianhydride

[0251] CpODA: Norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride

[0252] [Diamine component]

[0253] TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0254] m-TD: m-Tolidine

[0255] [Imidazole compounds]

[0256] 2-Pz: 2-phenylimidazole

[0257] 1,2-DMz: 1,2-dimethylimidazole

[0258] 1-Mz: 1-Methylimidazole

[0259] [Solvent]

[0260] NMP: N-methyl-2-pyrrolidone

[0261] Table 1-1 shows a tetracarboxylic acid component and a diamine component, and Table 1-2 shows a structural formula of an imidazole compound.

[0262] [Table 1-1]

[0263]

[0264] [Table 1-2]

[0265]

[0266] <Example 1>

[0267] [Preparation of polyimide precursor composition]

[0268] 1.84 g (5.7 mmol) of TFMB was added to a nitrogen-purged reaction vessel, and 23.26 g of N-methyl-2-pyrrolidone was added in an amount of 12% by mass of the total mass of the monomers (the sum of the diamine component and the carboxylic acid component), and stirred at room temperature for 1 hour. 1.00 g (4.6 mmol) of PMDA and 0.34 g (1.2 mmol) of a-BPDA were slowly added to the solution. Stirring was performed at room temperature for 6 hours to obtain a uniform and viscous polyimide precursor solution.

[0269] 2-phenylimidazole as an imidazole compound was dissolved in 4 times the mass of N-methyl-2-pyrrolidone to obtain a uniform solution having a solid content concentration of 20 mass % of 2-phenylimidazole. The imidazole compound solution was mixed with the above-synthesized polyimide precursor solution in such a manner that the amount of the imidazole compound was 0.5 mole relative to 1 mole of the repeating unit of the polyimide precursor, and stirred at room temperature for 3 hours to obtain a uniform and viscous polyimide precursor composition.

[0270] [Manufacturing of polyimide film / substrate laminate]

[0271] As a glass substrate, a 6-inch Eagle-XG (registered trademark) manufactured by Corning Incorporated (500 μm thick) was used. The polyimide precursor composition was applied to the glass substrate using a spin coater, and was directly heated from room temperature to 420°C on the glass substrate under a nitrogen atmosphere (oxygen concentration of less than 200 ppm), and imidization was performed thermally to obtain a polyimide film / substrate laminate. Regarding peel strength, a test sample with a width of 5 mm was prepared from the obtained polyimide film / glass laminate for measurement. Regarding other film properties, the laminate was immersed in water at 40°C (for example, a temperature in the range of 20°C to 100°C), the polyimide film was peeled off from the glass substrate, and after drying, the properties of the polyimide film were evaluated. The film thickness of the polyimide film is about 10 μm. The evaluation results are shown in Table 2.

[0272] <Examples 2 to 22>

[0273] In Example 1, a polyimide precursor composition was obtained in the same manner as in Example 1 except that the tetracarboxylic acid component, diamine component and imidazole compound were changed to the compounds and amounts (molar ratios) shown in Tables 2 and 3. Thereafter, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated.

[0274] <Comparative Examples 1 to 30>

[0275] In Example 1, a polyimide precursor composition was obtained in the same manner as in Example 1 except that the tetracarboxylic acid component, diamine component and imidazole compound were changed to the compounds and amounts (molar ratios) shown in Tables 4 to 7. Thereafter, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated.

[0276] [Table 2]

[0277]

[0278] eq: represents the number of moles per 1 mole of repeating unit. (same in other tables)

[0279] [Table 3]

[0280]

[0281] [Table 4]

[0282]

[0283] [Table 5]

[0284]

[0285] [Table 6]

[0286]

[0287] *) 5% weight loss temperature (℃)

[0288] 70μm thick, 400nm

[0289] [Table 7]

[0290]

[0291] The following were confirmed from the results of Tables 2 to 7.

[0292] When the amount of PMDA in the acid component is large or the total amount of PMDA and s-BPDA is large (Table 4: Comparative Examples 1 to 8), the transmittance at 450 nm is low and the peel strength is also low. In the system to which 5 mol% of a-BPDA and OPDA are added in total, by increasing the amount of imidazole compound added, it is observed that the peel strength is improved and the transmittance is also improved, but the transmittance at 450 nm is limited to 77%, which is lower than the transmittance of the monomer composition of the example.

[0293] When no imidazole compound is added or the amount added is small (Table 5), even if the monomer composition is within the scope of the invention, the transmittance at 450nm is small and the peel strength is also small. In addition, when the amount of imidazole compound added is too much, the maximum viscosity retention rate is unqualified and the stability of the polyimide precursor composition is poor.

[0294] In the comparative examples (Table 6) using an alicyclic compound or a fluorine-containing compound as the main acid component, it was confirmed that the 1% weight loss temperature was low and the heat resistance was inferior to that of the monomer composition of the examples.

[0295] In Comparative Examples 15 to 19, the peel strength decreased as the amount of imidazole compound added increased. This indicates that when an alicyclic compound is used as the acid component, the problem of insufficient adhesion does not exist, but the adhesion may be deteriorated due to the addition of the imidazole compound.

[0296] In the comparative examples (Table 7) in which the proportion of PMDA in the acid component was small, the linear thermal expansion coefficient was larger than that of the examples.

[0297] <Viscosity Stabilization Evaluation>

[0298] The viscosity stabilization days of the polyimide precursor compositions having the monomer composition and the amount of imidazole compound added shown in Table 8 were evaluated.

[0299] After polymerization, when the polyimide precursor composition was stored at 23° C., the viscosity increased, reached a maximum value, and then decreased. When the maximum value was reached, it was evaluated as “viscosity stabilized.” The results are shown in Table 8.

[0300] [Table 8]

[0301]

[0302] [Adhesion test after inorganic thin film formation]

[0303] On the polyimide film surface of the polyimide film / substrate laminate manufactured in the same manner as in Examples 13, 21, and 22, SiOx and SiNx were sequentially formed into films of 400 nm each by plasma CVD. Afterwards, annealing treatment was performed at 380° C. for 10 minutes in an annealing furnace. The film was taken out of the annealing furnace for visual observation, but no peeling was observed between the polyimide film and the glass substrate, and between the polyimide film and the SiOx film. The results are shown in Table 9.

[0304] The polyimide film / substrate laminates produced in the same manner as in Comparative Examples 1 and 10 were subjected to the same annealing treatment, and as a result, peeling was observed between the polyimide film and the glass substrate.

[0305] [Table 9]

[0306]

[0307] Industrial Applicability

[0308] The present invention can be suitably used in the manufacture of flexible electronic devices, such as display devices such as liquid crystal displays, organic EL displays, and electronic paper, and light receiving devices such as solar cells and CMOS.

Claims

1. A polyimide precursor composition, characterized in that: It contains: A polyimide precursor having a repeating unit represented by the following general formula (I); and at least one imidazole compound contained in an amount ranging from 0.05 mol to 2 mol per 1 mol of the repeating unit of the polyimide precursor, [Chemistry 1] In the general formula (I), X1 is a tetravalent aliphatic group or aromatic group, Y1 is a divalent aliphatic group or aromatic group, R1 and R2 are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, wherein: 60 mol% to 90 mol% of X1 is represented by formula (1-1): [Chemistry 2] The structure shown in FIG. 1, wherein 10 to 40 mol % is selected from formula (1-2), formula (1-3) and formula (1-4): [Chemistry 3] At least one of the structures shown, 70 mol% or more of Y1 is of formula (B): [Chemistry 4] The structure shown.

2. The polyimide precursor composition according to claim 1, characterized in that 90 mol% or more of X1 is a structure selected from the group consisting of formula (1-1), formula (1-2), formula (1-3) and formula (1-4).

3. The polyimide precursor composition according to claim 1 or 2, wherein 90 mol% or more of Y1 is a structure represented by formula (B).

4. The polyimide precursor composition according to claim 1, characterized in that The imidazole compound is at least one selected from the group consisting of 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, and benzimidazole. A polyimide film obtained from the polyimide precursor composition according to claim 1.

6. A polyimide film / substrate laminate, characterized in that: It has: A polyimide film obtained from the polyimide precursor composition according to claim 1; and Base material.

7. The laminate according to claim 6, wherein: The laminate further has an inorganic thin film layer on the polyimide film.

8. The laminate according to claim 6 or 7, wherein: The peel strength between the polyimide film and the substrate is 20 gf / cm or more.

9. The laminate according to claim 6 or 7, wherein: The substrate is a glass substrate.

10. A method for producing a polyimide film / substrate laminate, comprising: (a) a step of coating the polyimide precursor composition according to claim 1 on a substrate; and (b) A step of heat-treating the polyimide precursor on the substrate to laminate a polyimide film on the substrate.

11. The method for producing a laminate according to claim 10, wherein: After the step (b), the method further comprises the step of (c) forming an inorganic thin film layer on the polyimide film of the laminate.

12. A method for manufacturing a flexible electronic device, comprising: (d) a step of forming at least one layer selected from a conductor layer and a semiconductor layer on the inorganic thin film layer of the laminate produced according to claim 11; and (e) A step of peeling the substrate and the polyimide film.

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