Polyimide precursor compositions, polyimide films, and polyimide film / substrate laminates

Abstract

This invention discloses a polyimide precursor composition comprising a polyimide precursor with repeating units represented by the following general formula (I), and a specified amount of at least one imidazole compound as an optional component. Using this polyimide precursor composition, it is possible to manufacture a polyimide film that exhibits the advantages of aromatic polyimide films such as heat resistance and coefficient of linear thermal expansion, while also improving light transmittance and adhesion in polyimide film / substrate laminates. In the formula, X1 comprises (i) at least 50 mol% of the structure of formula (1-1), and at least 70 mol% of the structures of formula (1-1) and (1-2), or (ii) at least 70 mol% of the structure of formula (1-1) and / or the structure of formula (1-2), and Y1 comprises at least 70 mol% of the structure of formula (B). However, in the case of (ii) above, the imidazole compound is contained in an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 mol of the polyimide precursor.

Description

Technical Field

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

[0002] Polyimide films possess excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability, making them widely used in electrical and electronic devices, semiconductors, and other fields. On the other hand, in recent years, with the advent of a highly information-driven society, there has been continuous development of optical materials such as optical fibers or waveguides in optical communication, and liquid crystal alignment films or protective films for color filters in display devices. Particularly in the display device field, research is actively underway on lightweight and highly flexible plastic substrates as alternatives to glass substrates, as well as the development of bendable or rollable displays.

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

[0004] Generally speaking, flexible films are difficult to maintain planarity, making it difficult to uniformly and precisely form semiconductor elements such as TFTs and fine wiring on them. 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, comprising the following steps: coating a specific precursor resin composition onto a carrier substrate to form a solid polyimide resin film; forming a circuit on the resin film; and forming a solid resin film with the circuit on a peel-off surface of the carrier substrate".

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

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

[0007] Polyimide is typically colored yellowish-brown, which limits its use in transmissive devices such as liquid crystal displays with backlights. However, in recent years, polyimide films with excellent light transmittance in addition to mechanical and thermal properties have been developed, making them promising substrates for display applications. For example, Patent Document 3 describes a semi-alicyclic polyimide that, in addition to light transmittance, also possesses excellent mechanical properties or heat resistance.

[0008] On the other hand, aromatic polyimides used as substrates for flexible electronic devices, for example, are disclosed in Patent Documents 4 and 5, which use a diamine component containing a fluorinated aromatic diamine such as 2,2'-bis(trifluoromethyl)benzidine (TFMB). Furthermore, for this application, Patent Documents 6, 7, and 8 disclose examples of using a diamine component containing an aromatic diamine compound with ester bonds. Polyimides containing aromatic diamine compounds with ester bonds are also known to be used in copper foil laminates (e.g., Patent Document 9) and for forming release layers (Patent Document 10). In addition, Patent Documents 11-15 also disclose examples of using a diamine component containing an aromatic diamine compound with ester bonds. [Previous Technical Documents] [Patent Literature]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2010-202729 [Patent Document 2] International Publication No. 2018 / 221607 [Patent Document 3] International Publication No. 2012 / 011590 [Patent Document 4] International Publication No. 2009 / 107429 [Patent Document 5] International Publication No. 2019 / 188265 [Patent Document 6] Japanese Patent Application Publication No. 2021-175790 [Patent Document 7] International Publication No. 2017 / 051827 [Patent Document 8] Chinese Patent Application Publication No. 110003470 [Patent Document 9] Japanese Patent Application Publication No. 2021-195380 [Patent Document 10] International Publication No. 2016 / 129546 [Patent Document 11] International Publication No. 2021 / 261177 [Patent Document 12] U.S. Patent Application Publication No. 2022 / 0135797 [Patent Document 13] Japanese Patent Application Publication No. 7-133349 [Patent Document 14] Japanese Patent Application Publication No. 2020-164704 [Patent Document 15] U.S. Patent Application Publication No. 2021 / 0017336 Summary of the Invention

[0010] [The problem the invention aims to solve] In recent years, TFT film deposition methods have been continuously improved, with film deposition temperatures decreasing compared to the past. However, high-temperature processing is still required in customized processes. Furthermore, since a larger process range results in better yield, the heat resistance of the substrate film should be as high as possible. Aromatic polyimides have issues with coloring, but generally exhibit excellent heat resistance. Therefore, if coloring is minimized, they may be suitable as substrates for display applications.

[0011] Especially in smartphones equipped with under-display cameras, since light passes through the display to reach the camera, the polyimide film used in the display must have high light transmittance, particularly within the sensor's sensitivity range. Furthermore, for example, to prevent the bent portions of flexible displays from turning white, a high modulus of elasticity is required.

[0012] As described above, examples of the use of 2,2'-bis(trifluoromethyl)benzidine (TFMB) are disclosed in Patent Documents 4 and 5. However, the inventors conducted research and discovered the following problem: during the formation of electronic devices from polyimide film / glass substrate laminates using TFMB as a monomer component, the polyimide film easily peels off from the glass substrate. This peeling easily occurs when the laminate is exposed to high temperatures after an inorganic thin film with gas barrier function is formed on the polyimide film / glass substrate laminate.

[0013] Furthermore, in the manufacturing of flexible electronic devices, there is sometimes a step of cutting large-sized polyimide film / glass substrate laminates (including after component formation) into individual flexible electronic devices (semi-finished products). If the adhesion between the polyimide film and the glass substrate is insufficient, peeling may occur between the polyimide film and the glass substrate during this step. This is believed to be because polyimide readily absorbs moisture, thus absorbing atmospheric moisture from the cut end face (with a barrier film on top) and expanding, leading to peeling when the adhesion is weak. Also, in the laser separation step of peeling the polyimide film from the glass substrate, if the adhesion strength between the polyimide film and the glass substrate is high, a lower laser intensity is sufficient, resulting in less change (no change) in the processed polyimide. On the other hand, if the adhesion is weak, an increased laser intensity is required, which may lead to discoloration or a decrease in the mechanical properties of the processed polyimide. Therefore, the polyimide film needs to have extremely high adhesion to the glass substrate, i.e., peel strength.

[0014] The aforementioned documents 6-15 do not disclose the invention of this case at all. Furthermore, the polyimide film used in flexible display substrates has other problems. Patent documents 6 and 7 describe examples of using a diamine component containing 4-aminobenzoic acid (APAB; referred to as 4-BAAB in this case), but the film's colorfastness is insufficient. Patent document 8 requires a diamine compound with a specific structure, resulting in insufficient colorfastness and elastic modulus of the film. The polyimide precursor compositions described in patent documents 11, 14, and 15 also require a diamine compound with a specific structure, failing to meet requirements for flexible display substrate applications such as haze. Moreover, the polyimide films obtained from polyimide precursor compositions for other applications described in patent documents 9, 10, 12, and 13 do not meet the performance requirements for display applications, including adhesion.

[0015] Therefore, the object of the present invention is to provide a polyimide precursor composition for manufacturing polyimide films, wherein the polyimide film not only exhibits the advantages of aromatic polyimide films such as heat resistance and coefficient of linear thermal expansion, but is also suitable for flexible electronic device applications such as light transmittance and adhesion in polyimide film / substrate laminates, particularly for flexible display substrates. Furthermore, the object of the present invention is to provide a polyimide film and a polyimide film / substrate laminate obtained from the polyimide precursor. [Technical means to solve the problem]

[0016] The main disclosures of this application are summarized as follows. Inventions related to items A1 to A14 are referred to as Invention Series A, and inventions related to items B1 to B12 are referred to as Invention Series B.

[0017] The inventions in series A are as follows. A1. A polyimide precursor composition comprising a polyimide precursor whose repeating unit is represented by the following general formula (I), and at least one imidazole compound as an optional component in an amount of 1 mol less than 1 mol relative to the repeating unit of the polyimide precursor. [Chemistry 1] (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 independently hydrogen atoms, alkyl groups with 1 to 6 carbon atoms, or alkyl-silyl groups with 3 to 9 carbon atoms, wherein, X1 satisfies either (i) or (ii). (i) Contains at least 50 mol% of the structure represented by Equation (1-1), and contains at least 70 mol% of the structures represented by Equation (1-1) and Equation (1-2) in total. (ii) Containing 70 mol% or more of the structure represented by formula (1-1) and / or the structure represented by formula (1-2), [Chemistry 2] Y1 contains more than 70 mol% of the structure represented by formula (B); [Chemistry 3] ) However, in the case of (ii) above, the condition is that at least one imidazole compound is contained as an essential component in an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 mol of the polyimide precursor.

[0018] A2. The polyimide precursor composition as described in item A1 above, characterized in that: 60 mol% or more of X1 has a structure represented by formula (1-1).

[0019] A3. The polyimide precursor composition described in any of the preceding items, wherein 80 mol% or more of Y1 is represented by the structure of formula (B).

[0020] A4. The polyimide precursor composition as described in any of the preceding items, wherein it further contains at least one imidazole compound in an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 mol of the polyimide precursor.

[0021] A5. The polyimide precursor composition as described in item A4 above, characterized in that: the imidazole compound is selected from at least one of the group consisting of 1,2-dimethylimidazolium, 1-methylimidazolium, 2-methylimidazolium, 2-phenylimidazolium, 1-phenylimidazolium, imidazolium and benzimidazole.

[0022] A6. The polyimide precursor composition as described in any of the preceding items, wherein it contains at least one silane compound having a Si-ORa structure (wherein Ra is a hydrogen atom or a hydrocarbon group) in an amount exceeding 0 parts by mass and less than 60 parts by mass relative to the total of 100 parts by mass of the tetracarboxylic dianhydride and the diamine compound used in manufacturing the polyimide precursor composition.

[0023] A7. The polyimide precursor composition as described in item A6 above, wherein the silane compound is represented by the following formula, (RaO)nSi(Rb)4-n (In the formula, n is an integer from 1 to 4, Ra is a hydrogen atom or a straight-chain or branched alkyl group with 1 to 8 carbon atoms, and Rb is an alkyl or aryl group with 10 or fewer carbon atoms).

[0024] A8. A polyimide film obtained from a polyimide precursor composition as described in any of the preceding claims.

[0025] A9. A polyimide film / substrate laminate, characterized by having: Polyimide films obtained from polyimide precursor compositions as described in any of the preceding items, and Substrate.

[0026] A10. The laminate as described in item A9 above, wherein an inorganic thin film layer is further formed on the polyimide film of the laminate.

[0027] A11. The laminate as described in any of the preceding items, wherein the substrate is a glass substrate.

[0028] A12. A method for manufacturing a polyimide film / substrate laminate, comprising the following steps: (a) Applying the polyimide precursor composition as described in any of the preceding items onto a substrate; and (b) The polyimide precursor is heat-treated on the substrate to deposit a polyimide film on the substrate.

[0029] A13. The method for manufacturing a laminate as described in item A12 above, wherein after step (b) above, the following step is further included: (c) An inorganic thin film layer is formed on the polyimide film of the above-mentioned laminate.

[0030] A14. A method for manufacturing a flexible electronic device, comprising the following steps: (d) On the inorganic thin film layer of the laminate manufactured in item A13 above, at least one layer selected from conductive layers and semiconductor layers is formed; and (e) Peel the above-mentioned substrate from the above-mentioned polyimide film. A15. A flexible electronic device comprising a polyimide film as described in item A8 above. A16. A flexible electronic device substrate comprising a polyimide film as described in item A8 above.

[0031] The specification of this case also reveals inventions of a different form than those described above, namely, inventions of series B. B1. A polyimide precursor composition comprising: The repeating unit is a polyimide precursor represented by the following general formula (I), and At least one imidazole compound having an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 mol of the aforementioned polyimide precursor. [Chemistry 4] (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 independently hydrogen atoms, alkyl groups with 1 to 6 carbon atoms, or alkyl-silyl groups with 3 to 9 carbon atoms, wherein, X1 contains 70 mol% or more of the structure represented by equation (1-1) and / or the structure represented by equation (1-2), [Chemistry 5] Y1 contains more than 50 mol% of the structure represented by formula (B); [Chemistry 6] )

[0032] B2. The polyimide precursor composition as described in item B1 above, characterized in that: 40 mol% or more of X1 has a structure represented by formula (1-1).

[0033] B3. The polyimide precursor composition described in any of the preceding items, wherein 60 mol% or more of Y1 is of the structure represented by formula (B).

[0034] The polyimide precursor composition described in any of the preceding items, wherein X1 comprises a total of 60 mol% or more of the structure represented by formula (1-1) and the structure represented by formula (1-2).

[0035] B5. The polyimide precursor composition as described in any of the preceding items, wherein the imidazole compound is selected from at least one of the group consisting of 1,2-dimethylimidazolium, 1-methylimidazolium, 2-methylimidazolium, 2-phenylimidazolium, 1-phenylimidazolium, imidazolium and benzimidazole.

[0036] B6. A polyimide film obtained from a polyimide precursor composition as described in any of the preceding items.

[0037] B7. A polyimide film / substrate laminate, characterized by having: A polyimide film obtained from a polyimide precursor composition as described in any of the preceding items; and Substrate.

[0038] B8. The laminate as described in item B7 above, wherein an inorganic thin film layer is further formed on the polyimide film of the laminate.

[0039] B9. The laminate as described in any of the preceding items, wherein the substrate is a glass substrate.

[0040] B10. A method for manufacturing a polyimide film / substrate laminate, comprising the following steps: (a) Applying the polyimide precursor composition as described in any of the preceding items onto a substrate; and (b) The polyimide precursor is heat-treated on the substrate to deposit a polyimide film on the substrate.

[0041] B11. The method for manufacturing a laminate as described in item B10 above, wherein after step (b) above, the following step is further included: (c) An inorganic thin film layer is formed on the polyimide film of the above-mentioned laminate.

[0042] B12. A method for manufacturing a flexible electronic device, comprising the following steps: (d) On the inorganic thin film layer of the laminate manufactured in item B11 above, at least one layer selected from conductive layers and semiconductor layers is formed; and (e) Peel the above-mentioned substrate from the above-mentioned polyimide film. [Effects of the Invention]

[0043] According to the present invention, a polyimide precursor composition can be provided for manufacturing a polyimide film that exhibits the advantages of aromatic polyimide films, such as heat resistance and coefficient of linear thermal expansion, while also improving light transmittance and adhesion in polyimide film / substrate laminates. Specifically, the polyimide precursor composition of the present invention is most suitable for manufacturing polyimide films used as substrates for flexible displays. Furthermore, the present invention can provide a polyimide film and a polyimide film / substrate laminate obtained from this polyimide precursor.

[0044] Furthermore, according to one embodiment of the present invention, a polyimide precursor composition with more stable viscosity can be provided.

[0045] Furthermore, according to one aspect of the present invention, a polyimide film and a polyimide film / substrate laminate obtained using the above-described polyimide precursor composition can be provided. Furthermore, according to a different aspect of the present invention, a method for manufacturing a flexible electronic device using the above-described polyimide precursor composition and a flexible electronic device can be provided. Implementation

[0046] In this application, "flexible (electronic) device" means a device that is flexible in nature, typically formed by creating a semiconductor layer (such as transistors or diodes as components) on a substrate. "Flexible (electronic) device" differs from previous devices such as COF (Chip on Film), which mount "rigid" semiconductor components like IC (Integrated Circuit) chips on an FPC (Flexible Printed Circuit Board). However, there is no problem in integrating "rigid" semiconductor components such as IC chips onto a flexible substrate or electrically connecting them for use in order to operate or control the "flexible (electronic) device" of this application. Examples of suitable flexible (electronic) devices include: liquid crystal displays, organic EL displays, electronic paper displays, solar cells, and CMOS (Complementary Metal Oxide Semiconductor) light-receiving devices. More specifically, the term "flexible (electronic) device substrate" does not include flexible wiring substrates (also known as flexible substrates, flexible printed wiring boards, etc.).

[0047] In this application, when the terms "for flexible (electronic) device substrates" and "for flexible display substrates" are used to refer to polyimide film, it means that the polyimide film itself is a major component of the substrate present in the finished product (or the substrate itself), and does not mean that the film or layer is not present in the finished product, or that it is an auxiliary layer deposited on the substrate. For example, the release layer is not a substrate. When the terms "for flexible (electronic) device substrates" and "for flexible display substrates" are used to describe polyimide precursor compositions, it refers to the polyimide precursor composition used to directly manufacture polyimide films for the aforementioned substrates. Specifically, a polyimide film for "flexible (electronic) device substrates (including flexible display substrates; hereinafter the same)" is obtained by coating the polyimide precursor composition onto a substrate and imidizing it. Therefore, when two or more polyimide precursor compositions (intermediate compositions) are mixed to manufacture a polyimide film, a single polyimide precursor composition is not "for flexible (electronic) device substrates" as defined in this application. This is because the structure of the obtained polyimide film depends on the structure of the polyimide precursor composition used to directly manufacture the polyimide film. Furthermore, although copper (or metal) foil laminates are used to manufacture flexible wiring boards (flexible substrates, flexible printed wiring boards), they are not used to manufacture flexible (electronic) devices. Therefore, the polyimide precursor composition used in the manufacture of copper foil laminates is not the same as the polyimide precursor composition for "flexible (electronic) device substrates". Moreover, the definitions of the above terms are sometimes explained in more detail in this specification.

[0048] The following describes the polyimide precursor composition of the present invention, followed by a method for manufacturing a flexible electronic device. The following description focuses on Invention Series A; Invention Series B, which includes an imidazole compound as an essential component, will be described under the section on imidazole compounds. Unless otherwise stated, the description of Invention Series A also applies to Invention Series B.

[0049] <<Polyimine Precursor Compositions>> The polyimide precursor composition for forming a polyimide film contains a polyimide precursor. In a preferred embodiment, the polyimide precursor composition further contains a solvent in which the polyimide precursor is dissolved.

[0050] The polyimide precursor has repeating units represented by the following general formula (I).

[0051] [Chemistry 7] (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 independently hydrogen atoms, alkyl groups with 1 to 6 carbon atoms, or alkyl-silyl groups with 3 to 9 carbon atoms.) Polyamides with R1 and R2 being hydrogen atoms are preferred. When X1 and Y1 are aliphatic groups, the aliphatic groups are preferably groups with an alicyclic structure.

[0052] In all repeating units of the polyimide precursor, X1 contains at least 50 mol% of the structure represented by formula (1-1), and contains a total of at least 70 mol% of the structures represented by formula (1-1) and formula (1-2). Here, formula (1-1) and formula (1-2) are derived from oxyphthalic anhydride (ODPA) and 3,3',4,4'-biphenyltetracarboxylic anhydride (s-BPDA), respectively.

[0053] [Chemistry 8]

[0054] Furthermore, more than 70 mol% of Y1 is represented by the structure of formula (B), which is derived from the structure of 4-aminobenzoic acid 4-aminophenyl ester (abbreviated as 4-BAAB). [Chemistry 9]

[0055] By using a composition containing such a polyimide precursor, a polyimide film having high light transmittance and high modulus of elasticity, and improved adhesion in the polyimide film / substrate laminate can be produced. Further, the obtained polyimide film is also excellent in properties such as heat resistance and low linear thermal expansion coefficient, which are advantages of wholly aromatic polyimide films.

[0056] The polyimide precursor is described using monomers (tetracarboxylic acid component, diamine component, other components) of X1 and Y1 in the general formula (I), and then the manufacturing method is described.

[0057] In this specification, the tetracarboxylic acid component includes tetracarboxylic acids, tetracarboxylic dianhydrides, other tetracarboxylic acid silane esters, tetracarboxylic acid esters, tetracarbonyl chlorides and other tetracarboxylic acid derivatives used as raw materials for manufacturing polyimides. Although not particularly limited, it is more convenient to use tetracarboxylic dianhydrides in manufacturing. In the following description, an example of using tetracarboxylic dianhydrides as the tetracarboxylic acid component will be described. Further, the diamine component is a diamine compound having two amino groups (-NH2) used as a raw material for manufacturing polyimides.

[0058] In this specification, the polyimide film means both the one formed on a (carrier) substrate and present in the laminate, and the film after peeling off the substrate. Further, the material constituting the polyimide film, that is, the material obtained by heat-treating (imidizing) the polyimide precursor composition, is sometimes referred to as "polyimide material".

[0059] <X1 and Tetracarboxylic Acid Component> As described above, (i) or (ii) is satisfied. (i) In all repeating units of the polyimide precursor, preferably 50 mol% or more of X1 is a structure represented by the following formula (1-1) (derived from ODPA), and preferably the total amount of the structure represented by the formula (1-1) (derived from ODPA) and the structure represented by the formula (1-2) (derived from s-BPDA) is 70 mol% or more of X1. (ii) Under the condition of containing the following imidazole compound in an amount of 0.01 mol or more and less than 1 mol relative to 1 mol of the repeating unit of the polyimide precursor, the total amount of the structure represented by the formula (1-1) (derived from ODPA) and the structure represented by the formula (1-2) (derived from s-BPDA) is preferably 70 mol% or more of X1, and it may also contain only one of the structures of the formula (1-1) and the formula (1-2). Furthermore, in either case (i) or (ii), X1 can be constructed solely from the structure of Equation (1-1) and the structure of Equation (1-2) (i.e., the sum of the structure of Equation (1-1) and Equation (1-2) is 100 moles).

[0060] A structure of 60 mol% or higher for X1 (1-1) is preferred, as it is advantageous when high light transmittance is required. More preferably, a structure of 70 mol% or higher for X1 is preferred, even more preferably, a structure of 80 mol% or higher for X1 is preferred, even more preferably, a structure of 90 mol% or higher for X1 (1-1) is preferred, and a structure of 100 mol% for X1 (1-1) is also acceptable.

[0061] In X1, the combined ratio of the structures of formulas (1-1) and (1-2) is preferably 75 moles or more, and more preferably 80 moles or more, 90 moles or more, and 100 moles or more is also preferred. Therefore, the ratio of the structure of formula (1-2) is 50 moles or less, and can be 0%. By using a structure containing formula (1-2), the coefficient of linear thermal expansion and mechanical properties (elastic modulus, etc.) can be improved. For example, by using 10 moles to 40 moles, these properties and light transmittance can be improved in a balanced manner.

[0062] In this invention, the amount of a tetravalent aliphatic or aromatic group (referred to as "other X1") other than the structures represented by formulas (1-1) and (1-2) may be included as X1 without impairing the scope of the effects of this invention. As an aliphatic group, a tetravalent group having an alicyclic structure is preferred. Therefore, the tetracarboxylic acid component may also include "other tetracarboxylic acid derivatives" other than ODPA and s-BPDA in an amount of 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, relative to 100 mol% of the tetracarboxylic acid component. The amount of "other tetracarboxylic acid derivatives" is 0 mol% is also a preferred embodiment.

[0063] Furthermore, when the proportion of the structure of formula (1-1) in X1 (derived from ODPA) is less than 70 mol%, especially less than 60 mol%, it is preferable to include "other X1" in the following proportion: more than 0 mol%, for example, more than 10 mol%, and less than 30 mol%, for example, less than 20 mol%. In this case, the "other X1" is preferably a tetravalent group derived from tetracarboxylic acid dianhydrides having an aromatic ring containing a fluorine atom, such as 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), or a tetravalent group derived from 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA). Moreover, "other X1" is not limited to this case, as will be explained below.

[0064] As "other X1", it is preferably a tetravalent group having an aromatic ring, and more preferably a tetravalent group having an aromatic ring having 6 to 40 carbon atoms.

[0065] Examples of tetravalent groups having an aromatic ring include those listed below. However, groups equivalent to formulas (1-1) and (1-2) are excluded.

[0066] [Chemistry 10] (In the formula, Z1 is a direct bond or any of the following divalent groups;)

[0067] [Chemistry 11] In the formula, Z2 is a divalent organic group, Z3 and Z4 are amide bonds, ester bonds, and carbonyl bonds, respectively, and Z5 is an organic group containing an aromatic ring.

[0068] Specifically, Z2 can be exemplified by aliphatic hydrocarbon groups with 2 to 24 carbon atoms and aromatic hydrocarbon groups with 6 to 24 carbon atoms.

[0069] Specifically, Z5 can be exemplified by aromatic hydrocarbon groups with 6 to 24 carbon atoms.

[0070] As a tetravalent group with an aromatic ring, it can achieve both high heat resistance and high light transmittance of the obtained polyimide film, and therefore the following is particularly preferred.

[0071] [Chemistry 12] (In the formula, Z1 is a direct bond or a hexafluoroisopropylidene bond)

[0072] Among them, Z1 is better as a direct bond because it can take into account the high heat resistance, high light transmittance and low coefficient of linear thermal expansion of the obtained polyimide film.

[0073] Furthermore, as a preferred base, one can cite the example of a compound containing a fumonis group, where Z1 in the above formula (9) is represented by the following formula (3A).

[0074] [Chemistry 13] Z11 and Z12 are either single bonds or divalent organic groups, respectively, preferably both. Z11 and Z12 are preferably organic groups containing aromatic rings, for example, the structure represented by formula (3A1).

[0075] [Chemistry 14] (Z13 and Z14 are independently single bonds, -COO-, -OCO-, or -O-, wherein, when Z14 is bonded to a genus, it is preferred that Z13 is -COO-, -OCO-, or -O- and Z14 is a single bond; R91 is an alkyl or phenyl group with 1 to 4 carbon atoms, preferably methyl; n is an integer from 0 to 4, preferably 1)

[0076] Examples of tetracarboxylic acid components that provide repeating units of the general formula (I) having a tetravalent group of an aromatic ring in the X1 system include: pyromellitic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 9,9-bis(3,4-dicarboxyphenyl) pyromellitic acid, 4-(2,5-dioxytetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, and 3,3',4,4'-diphenyl Methyl ketone tetracarboxylic acid, 3,4'-oxophthalic acid, bis(3,4-dicarboxyphenyl) benzoyl benzoate, meta-triphenyl-3,4,3',4'-tetracarboxylic acid, p-triphenyl-3,4,3',4'-tetracarboxylic acid, dicarboxyphenyl dimethyl silane, dicarboxyphenoxy diphenyl sulfide, sulfonylmethane, or their derivatives such as tetracarboxylic dianhydride, tetracarboxylic silane ester, tetracarboxylic ester, and tetracarboxychlorodichloro. Examples of tetracarboxylic acid components providing repeating units of the general formula (I) containing a tetravalent group of an aromatic ring with a fluorine atom in the X1 system include: 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, or their derivatives such as tetracarboxylic dianhydride, tetracarboxylic silane ester, tetracarboxylic ester, and tetracarboxychlorodichlorodichloro. Tetracarboxylic acid components can be used alone or in combination.

[0077] As the tetracarboxylic acid component of the repeating unit of formula (I) in which X1 is a tetravalent group having an alicyclic structure, for example, the following can be cited: 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), octahydrobicylopentadiene-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, or derivatives thereof such as tetracarboxylic dianhydrides, tetracarboxylic silane esters, tetracarboxylic esters, and tetracarbonyl chlorides. The tetracarboxylic acid component can be used alone, or a plurality of kinds can be used in combination.

[0078] <Y one and diamine component>

[0079] As described above, among all repeating units in the polyimide precursor, the structure of the Y1 with 70 mol% or more of the formula (B) is preferred, and even more preferably the structure of the formula (B) with 80 mol% or more, 90 mol% or more, and 100 mol% is also preferred.

[0080] In this invention, a divalent aliphatic or aromatic group (referred to as "other Y1") other than the structure represented by formula (B) may be included as Y1 in an amount that does not impair the scope of the effects of this invention. That is, the diamine component, in addition to 4-aminobenzoic acid 4-aminophenyl ester (4-BAAB), may also include "other diamine compounds" in an amount of 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less relative to 100 mol% of the diamine component. An amount of 0 mol% of "other diamine compounds" is also a preferred embodiment.

[0081] Furthermore, when the proportion of the structure of formula (1-1) (derived from 4-BAAB) is less than 90 mol%, especially when it is less than 80 mol, it is preferable to contain "other Y1" in a proportion that is greater than 0 mol, for example, more than 10 mol, and less than 20 mol, for example, less than 15 mol. In this case, the "other Y1" is preferably a diamine compound having an ether bond in the molecular chain direction, such as 4,4-oxodiphenylamine (4,4-ODA) or 4,4'-bis(4-aminophenoxy)biphenyl (BAPB). Moreover, "other Y1" is not limited to this case, as will be explained below.

[0082] When "other Y1" is a divalent group with an aromatic ring, it is preferable to have a divalent group with an aromatic ring having 6 to 40 carbons, and more preferably a divalent group with an aromatic ring having 6 to 20 carbons.

[0083] Examples of divalent groups having an aromatic ring include the following.

[0084] [Chemistry 15] (In the formula, W1 is a direct bond or a divalent organic group, n11~n13 represent integers from 0 to 4, and R51, R52, and R53 are alkyl, halogen, hydroxyl, carboxyl, or trifluoromethyl groups with 1 to 6 carbon atoms, respectively.)

[0085] Specifically, W1 can be exemplified by: direct bonds, divalent bases represented by equation (5) below, and divalent bases represented by equation (6) below. However, bases equivalent to equation (B) are excluded.

[0086] [Chemistry 16]

[0087] [Chemistry 17] (In equation (6), R61 to R68 represent either a direct bond or any of the divalent bases represented by equation (5) above.)

[0088] Among them, since it can take into account the high heat resistance, high light transmittance and low coefficient of linear thermal expansion of the obtained polyimide, W1 is preferably one of the groups composed of direct bonds or groups represented by the formula -NHCO-, -CONH-, -COO-, -OCO-. In addition, W1 is also preferably any of the divalent groups represented by the above formula (6), wherein R61 to R68 are one of the groups composed of direct bonds or groups represented by the formula -NHCO-, -CONH-, -COO-, -OCO-.

[0089] Furthermore, as a preferred base, one can cite as an example that W1 in the above formula (4) is a compound containing a fumonis group represented by the following formula (3B).

[0090] [Chemistry 18] Z11 and Z12 are either single bonds or divalent organic groups, respectively, preferably both. Z11 and Z12 are preferably organic groups containing aromatic rings, for example, preferably structures represented by formula (3B1).

[0091] [Chemistry 19] (Z13 and Z14 are independently single bonds, -COO-, -OCO-, or -O-, wherein, when Z14 is bonded to a genus, it is preferred that Z13 is -COO-, -OCO-, or -O- and Z14 is a single bond; R91 is an alkyl or phenyl group with 1 to 4 carbon atoms, preferably phenyl; n is an integer from 0 to 4, preferably 1)

[0092] As another preferred base, compounds in formula (4) above where W1 is an exenylphenyl group, i.e., triphenyl diamine compounds, are particularly preferred if all of them are para-bonded.

[0093] As another preferred basis, examples can be found in compounds in formula (4) above where R61 and R62 are 2,2-propylenes in the structure of the first benzene ring of the W1 series formula (6).

[0094] As another better basis, we can cite the example of W1 in the above formula (4) which is represented by the following formula (3B2).

[0095] [Chemistry 20]

[0096] Regarding the provision of diamine components of Y1 having a divalent group of an aromatic ring, examples include: p-phenylenediamine, m-phenylenediamine, benzidine, 3,3'-diamino-biphenyl, 3,3'-bis(trifluoromethyl)benzidine, meta-toluidine, 3,4'-diaminobenzophenone, N,N'-bis(4-aminophenyl)-terephthalamide, N,N'-p-phenylbis(p-aminobenzophenone), 4-diaminobenzoic acid 4-aminophenoxy ester, bis(4-aminophenyl) terephthalate, biphenyl-4,4'-dicarboxylic acid bis(4- [1,1'-biphenyl]-4,4'-dicarboxylic acid bis(4-aminophenyl) ester, [1,1'-biphenyl]-4,4'-dimethylbis(4-aminobenzoate), 4,4'-oxodiphenylamine, 3,4'-oxodiphenylamine, 3,3'-oxodiphenylamine, 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-aminophenyl)benzene 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)guanidine, 3,3'-bis(trifluoromethyl)benzidine, 3,3'-bis((aminophenoxy)phenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(4-(4-aminophenoxy)diphenyl)guanidine, bis(4-(3-aminophenoxy)diphenyl)guanidine, 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-tris(2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-tris(2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-tris(2,4-bis(4-aminoanilino)-6-anilino ... Examples of diamine components that provide repeating units of the general formula (I) of the Y1 series having a divalent group containing a fluorine atom in an aromatic ring 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)furan, 4,4'-(((9H-furan-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1"-triphenyl]-4,4"-diamine, and 4,4'-([1,1'-binaphthyl]-2,2'-diylbis(oxy))diamine. The diamine components can be used alone, or in combination of several.

[0097] When "other Y1" is a divalent group with an alicyclic structure, it is more preferably a divalent group with an alicyclic structure having 4 to 40 carbon atoms, and even more preferably a divalent group with at least one aliphatic four to twelve-membered ring, and more preferably aliphatic six-membered ring.

[0098] Examples of divalent groups with alicyclic structures include the following.

[0099] [Chemistry 21] (In the formula, V1 and V2 are each a direct bond or a divalent organic group, n21 to n26 are each an integer from 0 to 4, R81 to R86 are each an alkyl, halo, hydroxyl, carboxyl or trifluoromethyl group with 1 to 6 carbon atoms, and R91, R92 and R93 are each selected from the group consisting of groups represented by the formula -CH2-, -CH=CH-, -CH2CH2-, -O-, -S-)

[0100] Specifically, V1 and V2 can be exemplified by direct bonds and divalent bases represented by the above equation (5).

[0101] Regarding the provision of diamine components of Y1 as a divalent group having an alicyclic structure, examples 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-dibutylcyclohexane, 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, diaminomethyloxybicycloheptane, isophorone diamine, 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. Diamine components can be used alone or in combination.

[0102] As the tetracarboxylic acid component and diamine component providing the repeating unit represented by the above general formula (I), aliphatic tetracarboxylic acids (especially acid dianhydrides) and / or aliphatic diamines other than alicyclic ones may be used, and their content relative to the total 100 mol% of the tetracarboxylic acid component and diamine component is preferably less than 30 mol%, more preferably less than 20 mol%, and even more preferably less than 10 mol% (including 0%).

[0103] By using the structure represented by formula (3B) as "other Y1", specifically diamine compounds such as 9,9-bis(4-aminophenyl)furan, it may be possible to increase Tg or reduce the phase difference (delay) in the film thickness direction.

[0104] In this invention, although described above, it is sometimes preferred that the polyimide precursor composition used to manufacture polyimide films does not contain a specific tetracarboxylic acid oxide compound and / or a specific diamine compound, or a specific compound. (a) Preferably, the diamine compound represented by H2N-Y2-N=N-Y2-NH2 or H2N-Y2-NHNH-Y2-NH2 (where Y2 is a divalent organic group) is present in very few (less than 5 moles in the repeating unit represented by general formula (I)) or not at all. (b) Surfactants and alkoxysilane compounds may be added, but it is preferable that they do not contain surfactants, and it is also preferable that the alkoxysilane compounds do not contain compounds other than those considered preferred in this invention. (c) Preferably, the diamine compound having a -SO2- group, the diamine compound having a fusiform structure, and the fluorine-containing diamine compound are not contained. (d) Preferably, the diamine compound containing the benzoylamine structure, such as 3,5-diaminobenzoylamine, is not included in the diamine component in an amount of more than 5 moles, and even more preferably, it is not included at all. (e) Preferably, the diamine compound represented by the following formula is not contained in an amount of 10:30 (=25:75) or more relative to 4-BAAB molar ratio. Even if it is contained, it is more preferably 15:85 or less in molar ratio, and even more preferably 10:90 or less. It is also preferable that it is not contained at all. [Chemistry 22] (f) Preferably, it is a combination of tetracarboxylic dianhydride and diamine compounds that do not contain repeating units that provide the structure of the following formula. [Chemistry 23] (g) Preferably, the diamine component does not contain 2,2'-bis(trifluoromethyl)benzidine or 1,4-diaminocyclohexane. (h) Preferably, the diamine component does not contain diamine monomers with nitrogen heterocyclic structures in an amount of 3 to 8 moles, and it is also preferable that it does not contain them at all.

[0105] Polyimide precursors can be manufactured from the aforementioned tetracarboxylic acid component and diamine component. The polyimide precursors used in this invention (comprising at least one polyimide precursor from the repeating unit represented by formula (I) above) can be classified according to the chemical structures employed in R1 and R2. 1) Polyamide (R1 and R2 are hydrogen atoms), 2) Polyamide (at least a portion of R1 and R2 is alkyl), 3) 4) Polysilane ester (at least a portion of R1 and R2 is alkylsilane). Furthermore, for each category, the polyimide precursor can be easily manufactured using the following manufacturing methods. However, the manufacturing method of the polyimide precursor used in this invention is not limited to the following manufacturing methods.

[0106] 1) Polyamide Polyimide precursors can be appropriately obtained in the form of a polyimide precursor solution by reacting a tetracarboxylic acid dianhydride (a tetracarboxylic acid component) with a diamine component in a solvent at a relatively low temperature, for example, below 120°C, while suppressing amide formation. The tetracarboxylic acid dianhydride and diamine components are approximately equal in moles, with a preferred ratio of 0.90 to 1.10 moles of diamine component relative to tetracarboxylic acid component [moles of diamine component / moles of tetracarboxylic acid component]. This ratio is more preferably 0.95 to 1.05.

[0107] More specifically, a diamine is dissolved in an organic solvent or water, and while stirring, tetracarboxylic dianhydride is slowly added to the solution. The mixture is stirred at a temperature of 0–120°C, preferably 5–80°C, for 1–72 hours to obtain a polyimide precursor, but this is not limited to any particular temperature range. When the reaction is carried out at temperatures above 80°C, the molecular weight varies depending on the temperature profile during polymerization. Furthermore, heat can cause amide formation, which may prevent the stable production of the polyimide precursor. The order of addition of the diamine and tetracarboxylic dianhydride in the above manufacturing method is preferred as it increases the molecular weight of the polyimide precursor. Alternatively, reversing the order of addition of the diamine and tetracarboxylic dianhydride in the above manufacturing method reduces the amount of precipitate, which is also preferred. When water is used as a solvent, it is preferable to add an imidazole such as 1,2-dimethylimidazolium or a base such as triethylamine in an amount that is preferably 0.8 times or more equivalent to the carboxyl group of the generated polyamide (polyimide precursor).

[0108] 2) Polyamide Tetracarboxylic acid dianhydride is reacted with any alcohol to obtain a diester dicarboxylic acid, which is then reacted with a chlorinating agent (such as thionyl chloride or oxalyl chloride) to obtain a diester dicarboxylic acid chloride. This diester dicarboxylic acid chloride is stirred with a diamine for 1 to 72 hours within a temperature range of -20 to 120°C, preferably -5 to 80°C, to obtain a polyimide precursor. When the reaction is carried out above 80°C, the molecular weight varies depending on the temperature profile during polymerization. Furthermore, heat can cause amide formation, which may prevent the stable production of the polyimide precursor. Alternatively, the polyimide precursor can be easily obtained by dehydrating and condensing the diester dicarboxylic acid with the diamine using a phosphorus-based condensing agent or a carbodiamide condensing agent.

[0109] The polyimide precursor obtained by this method is relatively stable, and therefore can also be purified by adding solvents such as water or alcohol for reprecipitation.

[0110] 3) Polyamide silicone ester (indirect method) The diamine is first reacted with a silanizing agent to obtain a silanized diamine. If necessary, the silanized diamine is purified by distillation or other methods. Then, the silanized diamine is dissolved in a dehydrated solvent, and while stirring, tetracarboxylic acid dianhydride is slowly added at a temperature of 0–120°C, preferably 5–80°C, for 1–72 hours to obtain a polyimide precursor. When the reaction is carried out above 80°C, the molecular weight changes depending on the temperature profile during polymerization; furthermore, heat can cause silylimation, which may prevent the stable production of the polyimide precursor.

[0111] 4) Poly(silane ester) (direct method) The polyamide solution obtained by method 1) is mixed with a silanizing agent and stirred for 1 to 72 hours within the range of 0 to 120°C, preferably 5 to 80°C, to obtain a polyimide precursor. When the reaction is carried out at temperatures above 80°C, the molecular weight changes depending on the temperature profile during polymerization. Furthermore, heat can cause amide formation, which may prevent the stable production of the polyimide precursor.

[0112] Using a chlorine-free silanizing agent as the silanizing agent used in methods 3) and 4) is preferable because it eliminates the need for purification of the silanized polyamide or the resulting polyimide. Examples of chlorine-free silanizing 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.

[0113] Furthermore, in the silanization 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 directly used as polymerization catalysts for polyimide precursors.

[0114] The solvent used in preparing polyimide precursors is preferably water, or non-protic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidineone, and dimethyl sulfoxide. As long as the raw material monomer components and the generated polyimide precursor are dissolved, any type of solvent can be used without problems, and therefore its structure is not limited. Suitable solvents include water, or acetamide 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; 1,3-dimethyl-2-imidazolidinedione; cyclobutane; and dimethyl sulfoxide. Furthermore, other common organic solvents can also be used, such as 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, naphtha-based solvents, etc. Moreover, multiple solvents can be used in combination.

[0115] In the manufacture of polyimide precursors, the monomer and solvent are added to a concentration of, for example, 5 to 45% by mass of the solid content of the polyimide precursor (converted mass concentration of polyimide) for reaction, but there are no particular limitations.

[0116] The logarithmic viscosity of the polyimide precursor is not particularly limited, but it is preferably 0.2 dL / g or higher, more preferably 0.3 dL / g or higher, and even more preferably 0.4 dL / g or higher, in a 0.5 g / dL N-methyl-2-pyrrolidone solution at 30°C. If the logarithmic viscosity is 0.2 dL / g or higher, the molecular weight of the polyimide precursor is higher, resulting in polyimide with excellent mechanical strength or heat resistance.

[0117] <Imidazole compounds> The polyimide precursor composition may contain at least one imidazole compound. The imidazole compound is not particularly limited, as long as it has an imidazole skeleton, such as 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 1-phenylimidazole, imidazole, and benzimidazole. Multiple imidazole compounds may also be used in combination. In one embodiment, the imidazole compound is preferably selected from imidazole compounds other than 1,2-dimethylimidazole, preferably dimethyl-substituted imidazole compounds other than 1,2-substituted imidazole compounds, monomethyl-substituted imidazole compounds, aromatic-substituted imidazole compounds, and especially preferably 2-phenylimidazole, 1-phenylimidazole, imidazole, and benzimidazole.

[0118] The content of imidazole compounds in the polyimide precursor composition can be appropriately selected by considering the balance between the additive effect and the stability of the polyimide precursor composition. When imidazole compounds are added, their amount (total content) relative to 1 mol of the repeating unit of the polyimide precursor should exceed 0 mol, and to achieve a certain degree of additive effect, it should be 0.01 mol or more, preferably 0.02 mol or more. On the other hand, from the viewpoint of viscosity stability of the polyimide precursor composition, it is preferable to be less than 1 mol, and more preferably less than 0.8 mol. The addition of imidazole compounds is effective in improving light transmittance and adhesion under long-term high-temperature environments such as annealing treatment. Especially when the ratio of the structure of formula (1-1) in X1 (derived from ODPA) is less than 90 mol%, particularly less than 80 mol, it is advisable to add an imidazole compound.

[0119] Imidazole compounds can solve the problem of a small ratio of the structure of formula (1-1) (derived from ODPA) in X1, and also the problem of a small combined ratio of the structure of formula (1-1) (derived from ODPA) and the structure of formula (1-2) (derived from s-BPDA). When adding an imidazole compound, the ratio of the structure of formula (1-1) (derived from ODPA) in X1 can be set to 0 mol% or more. That is, if the combined ratio of the structure of formula (1-1) and the structure of formula (1-2) in X1 is 70 mol% or more, then only one of them needs to be included, and the ratio of the structure of formula (1-1) can also be zero.

[0120] In summary, as specified in Invention Series A, this application discloses a state in which the imidazole compound is not an essential component (condition (i)) and a state in which the imidazole compound is an essential component (condition (ii)).

[0121] Furthermore, this application also discloses another invention, namely Invention Series B, which requires the addition of an imidazole compound. A polyimide precursor composition comprising a polyimide precursor with repeating units represented by the above general formula (I), and X1 contains a structure represented by formula (1-1) of 70 mol% or more (80 mol% or more or 90 mol% or more is preferred) and / or a structure represented by formula (1-2). Y1 contains a structure represented by formula (B) of 50 mol% or more (60 mol% or more, 70 mol% or more, or 80 mol% or more are also preferred). Furthermore, it contains at least one imidazole compound in an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 mol of the aforementioned polyimide precursor. In this other invention, elements and matters other than those specified above follow the description of Invention Series A in this application.

[0122] <Silane compounds> Adding a silane compound (hereinafter, sometimes simply referred to as "silane compound") having a Si-ORa structure (Ra being a hydrogen atom or a hydrocarbon group) as an additive to the polyimide precursor composition is also preferable. The addition of silane compounds is effective in improving light transmittance. Ra is preferably a hydrocarbon group with 10 or fewer carbon atoms, preferably an alkyl or aryl group, especially with 1 to 8 carbon atoms, more preferably a straight-chain or branched alkyl group with 1 to 4 carbon atoms, and particularly preferably methyl or ethyl. Examples include compounds represented by (RaO)nSi(Rb)4-n (n being an integer from 1 to 4). As described above, n is preferably 1 to 3, more preferably 2 or 3. Rb is a hydrocarbon group with 10 or fewer carbon atoms, preferably an alkyl or aryl group, more preferably an aryl group, and particularly preferably phenyl.

[0123] Specifically, examples include: methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, dimethoxydiphenylsilane, diethoxydiphenylsilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane, trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, triethylethoxysilane, trihexylmethoxysilane, trihexylethoxysilane, triphenylmethoxysilane, and triphenylethoxysilane, etc. Two or more silane compounds can also be used in combination.

[0124] The amount of silane compound added can be appropriately selected considering the desired effect. When adding silane compound, its amount (total content) should not exceed 0 parts by mass relative to the total 100 parts by mass of the tetracarboxylic acid and diamine components. To achieve a certain degree of additive effect, it should be 0.05 parts by mass or more, preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more. From the point of view of physical property balance, it should be, for example, 60 parts by mass or less, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 35 parts by mass or less, even more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less.

[0125] <Formulation of Polyimide Precursor Compositions and "Polyimide Precursor Compositions for Flexible Electronic Device Substrates"> The polyimide precursor composition used in this invention comprises at least one of the above-mentioned polyimide precursors, and preferably further comprises a solvent. Furthermore, as described above, it is also preferable to include at least one imidazole compound.

[0126] As a solvent, the solvent described above for preparing the polyimide precursor can be used. Generally, the solvent used in preparing the polyimide precursor can be used directly, i.e., the polyimide precursor solution can be used as is, but it can also be diluted or concentrated as needed. The imidazole compound (if added) is dissolved in the polyimide precursor composition. The concentration of the polyimide precursor is not particularly limited, but is typically 5-45% by mass in terms of polyimide equivalent mass concentration (solid content concentration). Here, polyimide equivalent mass refers to the mass when all repeating units are completely amided.

[0127] The viscosity (rotational viscosity) of the polyimide precursor composition of this invention is not particularly limited. A rotational viscosity measured using an E-type rotational viscometer at a temperature of 25°C and a shear rate of 20 sec⁻¹ is preferably 0.01 to 1000 Pa·sec, more preferably 0.1 to 100 Pa·sec. Thixotropy can also be imparted as needed. Viscosities within the above range facilitate coating or film formation, suppress shrinkage, and provide excellent leveling properties, thus resulting in a good coating.

[0128] The polyimide precursor composition of the present invention may, as needed, contain chemical acetilimating agents (acetic anhydrides such as acetic anhydride, or amine compounds such as pyridine and isoquinoline), antioxidants, ultraviolet absorbers, fillers (inorganic particles such as silicon dioxide), dyes, pigments, coupling agents such as silane coupling agents, primers, flame retardants, defoamers, leveling agents, rheology control agents (flow aids), etc. Furthermore, when acetilimating the polyimide precursor composition of the present invention, thermal acetilimation is preferable; in this case, it is preferable not to contain acetic anhydrides such as acetic anhydride as chemical acetilimating agents.

[0129] The polyimide precursor composition can be prepared by adding an imidazole compound or a solution of an imidazole compound to a polyimide precursor solution obtained by the method described above and mixing. Alternatively, the tetracarboxylic acid component and the diamine component can be reacted in the presence of an imidazole compound.

[0130] The polyimide precursor composition of the present invention can be used as a composition for "flexible electronic device substrates (preferably flexible display substrates; hereinafter the same). As described above, in the present invention, the polyimide precursor composition for "flexible electronic device substrates" as described below refers to one that is directly coated onto a substrate.

[0131] <<Manufacturing of Polyimide Film / Substrate Laminates and Flexible Electronic Devices>> Polyimide film / substrate laminates can be manufactured using the polyimide precursor composition of the present invention (i.e., polyimide precursor composition for flexible electronic device substrates). The polyimide film / substrate laminate can be manufactured by the following steps: (a) coating the polyimide precursor composition onto a substrate; (b) heat-treating the polyimide precursor onto the substrate to manufacture a laminate (polyimide film / substrate laminate) with a polyimide film deposited on the substrate. Furthermore, step (b2) is also preferred to include the step of forming an inorganic thin film on the surface of the polyimide film after forming the polyimide film on the substrate.

[0132] In the manufacturing method of the flexible electronic device of the present invention, a further step is performed using the polyimide film / substrate laminate manufactured in steps (a) and (b) (preferably a further step (b2)), namely, (c) forming at least one layer selected from conductive layers and semiconductor layers on the polyimide film of the laminate; and (d) peeling the substrate from the polyimide film.

[0133] First, in step (a), the polyimide precursor composition is cast onto a substrate, and amided and desolventized by heat treatment to form a polyimide film, thereby obtaining a laminate of substrate and polyimide film (polyimide film / substrate laminate).

[0134] As the substrate, heat-resistant materials are used, such as plate or sheet substrates made of ceramic materials (glass, alumina, etc.), metal materials (iron, stainless steel, copper, aluminum, etc.), semiconductor materials (silicon, compound semiconductors, etc.), or film or sheet substrates made of heat-resistant plastic materials (polyimide, etc.). Generally, flat and smooth plate-shaped substrates are preferred, typically using glass substrates such as soda-lime glass, borosilicate glass, alkali-free glass, and sapphire glass; semiconductor substrates (including compound semiconductors) such as silicon, GaAs, InP, and GaN; and metal substrates such as iron, stainless steel, copper, and aluminum.

[0135] Glass substrates are particularly preferred as the substrate material. Flat, smooth, and large-area glass substrates have been developed and are readily available. The thickness of the plate-shaped substrate, such as the glass substrate, is not limited; from the viewpoint of ease of handling, it is, for example, 20 μm to 4 mm, preferably 100 μm to 2 mm. Furthermore, the size of the plate-shaped substrate is not particularly limited; one side (the long side in the case of a rectangle) is, for example, approximately 100 mm to approximately 4000 mm, preferably approximately 200 mm to approximately 3000 mm, and even more preferably approximately 300 mm to approximately 2500 mm.

[0136] These glass substrates and other substrates may also have an inorganic thin film (e.g., silicon oxide film) or a resin film formed on their surface.

[0137] There are no particular limitations on the casting method of the polyimide precursor composition on the substrate. Examples include previously known methods such as slot coating, die coating, doctor blade coating, spraying, inkjet coating, nozzle coating, spin coating, screen printing, rod coating, and electrodeposition.

[0138] In step (b), the polyimide precursor composition is heat-treated on a 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, drying within a temperature range of 50°C to 150°C followed by heat treatment, with 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.

[0139] 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. When the thickness is less than 1 μm, the polyimide film may not maintain sufficient mechanical strength; for example, when used as a substrate for flexible electronic devices, it may be unable to withstand stress and 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. If the thickness of the polyimide film becomes too thick, it may be difficult to achieve a thinner form factor for the flexible device. To maintain sufficient durability as a flexible device and to further achieve thinner profiles, the thickness of the polyimide film is preferably 2 to 50 μm.

[0140] In this invention, the polyimide film / substrate laminate preferably exhibits minimal warpage. The properties of the polyimide film can be evaluated by the residual stress between the polyimide film and the silicon substrate in the polyimide film / silicon substrate (wafer) laminate. The residual stress achievable by this invention will be described below.

[0141] The polyimide film in the polyimide film / substrate laminate may also have a second layer, such as an inorganic film, on its surface. Therefore, step (b2) is preferred, which includes the step of forming an inorganic film on the surface of the polyimide film formed on the substrate. The inorganic film is particularly preferably one that functions as a barrier layer for water vapor or oxygen (air). As a water vapor barrier layer, an example of an inorganic film comprising an inorganic material selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides, such as silicon nitride (SiNx), silicon oxide (SiOx), silicon oxynitride (SiOxNy), aluminum oxide (Al2O3), titanium oxide (TiO2), and zirconium oxide (ZrO2). Generally, known methods for forming such thin films include physical vapor deposition methods such as vacuum evaporation, sputtering, and ion plating, and chemical vapor deposition methods such as plasma CVD (chemical vapor deposition) and catalytic chemical vapor deposition (Cat-CVD). In these film formation methods including CVD, after film formation, the film is densified by high-temperature annealing at, for example, 350°C to 450°C to improve its barrier function. Furthermore, in this application, "inorganic thin film" refers to both the state before and after annealing. When only one of these states is referred to, it will be clearly indicated or can be understood from the context. Similarly, "polyimide film / substrate laminate" refers to both those having an "inorganic thin film" and those not having an "inorganic thin film".

[0142] The second layer can also be multiple layers. In this case, different types of inorganic films can be formed, and resin films can also be composited with inorganic films. As an example of the latter, a three-layer structure of barrier layer / polyimide layer / barrier layer can be formed on the polyimide film in a polyimide film / substrate laminate.

[0143] In step (c), using the polyimide / substrate laminate obtained in step (b), at least one layer selected from conductive layers and semiconductor layers is formed on the polyimide film (including those with a second layer such as an inorganic thin film on the surface of the polyimide film). These layers can be formed directly on the polyimide film (including those with a second layer), or they can be formed indirectly after other layers required for the device have been laminated.

[0144] The conductive layer and / or semiconductor layer are selected according to the components and circuits required by the target electronic device. In step (c) of the present invention, when forming at least one of the conductive layer and semiconductor layer, it is also preferable to form at least one of the conductive layer and semiconductor layer on the polyimide film on which the inorganic film is formed.

[0145] The conductive layer and the semiconductor layer include both those formed on the entire surface of the polyimide film and those formed on a portion of the polyimide film. The present invention can proceed to step (d) immediately after step (c), or it can form at least one layer selected from the conductive layer and the semiconductor layer in step (c), thereby forming the device structure, and then proceed to step (d).

[0146] When manufacturing a TFT liquid crystal display device as a flexible device, a TFT, such as metal wiring, amorphous silicon, or polycrystalline silicon, and transparent pixel electrodes are formed on a polyimide film on which an inorganic film is formed as needed across its entire surface. The TFT includes, for example, a gate metal layer, a semiconductor layer such as an amorphous silicon film, a gate insulating layer, and wiring connected to the pixel electrodes. The required structure for a liquid crystal display can also be formed on it using known methods. Furthermore, transparent electrodes and color filters can also be formed on the polyimide film.

[0147] In the manufacture of organic EL displays, in addition to forming transparent electrodes, light-emitting layers, hole transport layers, electron transport layers, etc., TFTs can be formed on polyimide films on the entire surface as needed.

[0148] The preferred polyimide film of the present invention has excellent heat resistance, toughness and other properties, so there are no particular limitations on the method of forming the circuit, components and other structures required for the device.

[0149] Next, in step (d), the substrate and the polyimide film are peeled off. The peeling method can be a mechanical peeling method that physically peels off the substrate by applying external force, but the polyimide film / substrate laminate of the present invention has excellent adhesion, so it is particularly preferred to peel off the substrate by using a so-called laser peeling method that peels off the substrate by irradiating it with laser light.

[0150] The device is constructed or assembled by using a polyimide film after peeling off the substrate as a substrate (semi-)product, and then forming or assembling the necessary structure or parts for the device. As described above, a flexible electronic device containing a polyimide film is completed, and in the flexible electronic device, the polyimide film functions as a substrate of the flexible electronic device.

[0151] Furthermore, as a different manufacturing method for flexible electronic devices, after manufacturing the polyimide film / substrate laminate using step (b) above, the polyimide film can be peeled off, and as in step (c) above, at least one layer selected from conductive layers and semiconductor layers and the desired structure can be formed on the polyimide film, thereby manufacturing a (semi) product using the polyimide film as a substrate.

[0152] <<Properties of Polyimide Films in Polyimide Film / Substrate Laminates>> When the polyimide film / substrate laminate described above is manufactured from the polyimide precursor composition of the present invention, it is particularly preferred for this purpose due to the excellent adhesion between the polyimide film and the substrate.

[0153] The following describes the range of characteristics of the polyimide film realized in this invention, with the first range, the second range, the third range, ..., the nth range representing the successively preferred ranges.

[0154] In addition to excellent light transmittance, thermal properties and heat resistance, the polyimide film manufactured from the polyimide precursor composition of the present invention also exhibits excellent adhesion to substrates such as glass substrates.

[0155] Adhesion can be assessed by peel strength. When 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 at a tensile speed of 2 mm / min and a 90° peel test, it is preferably 50 gf / cm (0.49 N / cm) or more (range 1), and even more preferably 100 gf / cm (0.98 N / cm) or more (range 2), 150 gf / cm (1.47 N / cm) or more (range 3), 200 gf / cm (1.96 N / cm) or more (range 4), 300 gf / cm (2.94 N / cm) or more (range 5), 400 gf / cm (3.92 N / cm) or more (range 6), and 500 gf / cm (4.9 N / cm) or more (range 7). Furthermore, the upper limit is typically below 5 kgf / cm (49.0 N / cm), and preferably below 3 kgf / cm (29.4 N / cm). Peel strength is usually measured in air or in the atmosphere.

[0156] As described above, the polyimide film / substrate laminate preferably has minimal warpage, and the characteristics of the polyimide film can be evaluated by the residual stress between the polyimide film and the silicon substrate in the polyimide film / silicon substrate (wafer) laminate. Details of the measurement are described in Japanese Patent No. 6798633. However, the polyimide film should be placed in a dry state at 23°C. The residual stress used for evaluation is preferably 20 MPa or less (first range), and more preferably 15 MPa or less (second range), 12 MPa or less (third range), and 10 MPa or less (fourth range).

[0157] In one embodiment of the present invention, when measuring with a film of 10 μm thickness, the transmittance of the polyimide film at 450 nm is preferably 73% or more (first range), and more preferably 74% or more (second range) and 75% or more (third range). Furthermore, when measuring with a film of 10 μm thickness, the yellowness (YI) of the polyimide film is preferably 13 or less (first range), and more preferably 12 or less (second range), 11 or less (third range), 10 or less (fourth range), and 9 or less (fifth range). Also, the yellowness (YI) is preferably 0 or more. Furthermore, when measuring with a 10 μm thick film, the haze value of the polyimide film is preferably less than 1.0% (range 1), and even more preferably less than 0.9% (range 2), less than 0.8% (range 3), less than 0.7% (range 4), and less than 0.6% (range 5).

[0158] The polyimide film of this invention has an extremely low coefficient of linear thermal expansion (CTE). In one embodiment of this invention, when measured with a film of 10 μm thickness, the CTE of the polyimide film at 150°C to 250°C is preferably below 27 ppm / K (first range), and more preferably below 25 ppm / K (second range), below 20 ppm (third range), below 15 ppm / K (fourth range), and below 13 ppm / K (fifth range).

[0159] The polyimide film (or the polyimide constituting the polyimide film) of the present invention has excellent heat resistance, and the 1% weight loss temperature is preferably 512°C or higher (first range), and even more preferably 515°C or higher (second range), 520°C or higher (third range), and 522°C or higher (fourth range).

[0160] In one embodiment of the present invention, the glass transition temperature (Tg) of the polyimide film (or the polyimide constituting the polyimide film) is preferably 350°C or higher, more preferably 370°C or higher, even more preferably 390°C or higher, even more preferably 400°C or higher, even more preferably 410°C or higher, even more preferably 420°C or higher, even more preferably 430°C or higher, even more preferably 435°C or higher, and most preferably 440°C or higher.

[0161] The polyimide film of this invention exhibits a very high elastic modulus. In one embodiment of this invention, the elastic modulus of the polyimide film is preferably 6.5 GPa or higher (first range), and more preferably 6.9 GPa or higher (second range), 7.3 GPa or higher (third range), 7.5 GPa or higher (fourth range), 7.6 GPa or higher (fifth range), 8.0 GPa or higher (sixth range), and 8.3 GPa or higher (seventh range). The elastic modulus can be obtained from a film with a thickness of, for example, about 8 to 12 μm.

[0162] Furthermore, in one embodiment of the present invention, when the measurement is performed using a film with a thickness of 10 μm, the elongation at break of the polyimide film is preferably 10% or more (first range), and more preferably 20% or more (second range), 25% or more (third range), and 30% or more (fourth range).

[0163] Furthermore, in one of the preferred embodiments of the present invention, the tensile strength of the polyimide film is preferably 200 MPa or more (first range), and subsequently preferably 250 MPa or more (second range), 270 MPa or more (third range), and 300 MPa or more (fourth range). The tensile strength can be obtained from a film with a thickness of, for example, about 5 to 100 μm.

[0164] The preferred properties of polyimide film are that its adhesion, light transmittance, and elastic modulus all meet the "preferred range", and even more preferably, its linear thermal expansion coefficient and 1% weight loss temperature also meet the "preferred range".

[0165] Polyimide films possessing these characteristics, specifically polyimide films used in flexible electronic device substrates, are novel and independently patentable. A preferred embodiment is described below. (1) The polyimide film has a light transmittance of 74% or more at 450 nm (range 2), an elastic modulus of 6.9 GPa or more (range 2), preferably 7.3 GPa or more (range 3), and the linear thermal expansion coefficient and elongation at break meet the above-mentioned range 1. (2) The polyimide film has a light transmittance of 75% or more at 450 nm (range 3), preferably 76% (range 4), an elastic modulus of 7.3 GPa or more (range 3), and a linear thermal expansion coefficient and elongation at break that meet the above-mentioned range 1. (3) The transmittance of the polyimide film at 450 nm is 74% or more (range 2), preferably 75% or more (range 3), and the peel strength between the polyimide film and the substrate in the polyimide film / substrate laminate is 200 gf / cm or more (range 4), preferably 300 gf / cm or more (range 5).

[0166] The polyimide precursor composition of this invention can also be used to manufacture other forms of polyimide and separate polyimide films. There are no particular limitations on the manufacturing method; any known amide method can be appropriately applied. Suitable examples of the resulting polyimide include: films, coated films, powders, beads, molded articles, foams, etc.

[0167] Individual polyimide films can be manufactured using known methods. A representative method is as follows: a polyimide precursor composition is cast and coated onto a substrate, followed by heat amide formation on the substrate, and then the polyimide film is peeled off. Alternatively, a polyimide precursor composition can be cast and coated onto a substrate, heat-dried to produce a self-holding film, and then the self-holding film is peeled off from the substrate, for example, by using a tenter frame to hold the film, and heat amide formation is performed in a state where the film can be degassed from both sides, thereby obtaining a polyimide film.

[0168] The thickness of the individual polyimide film also depends on the application, but it is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 5 μm or more, and for example, less than 250 μm, preferably less than 150 μm, more preferably less than 100 μm, and even more preferably less than 50 μm. [Example]

[0169] The present invention will be further described below with reference to embodiments and comparative examples. However, the present invention is not limited to the following embodiments.

[0170] In the following examples, the evaluation was conducted using the following methods.

[0171] Evaluation of Polyimide Precursor Compositions [Viscosity stabilization and maximum viscosity retention assessment] When the polyimide precursor composition is stored at 23°C after polymerization, the viscosity increases, reaches its maximum viscosity, and then begins to decrease. Once it reaches its maximum viscosity, it is assessed as "viscosity stabilized." Furthermore, although the viscosity decreases after reaching the maximum viscosity, the ratio of the viscosity 30 days after reaching the maximum viscosity to the maximum viscosity is defined as the "maximum viscosity retention rate." Cases where the viscosity is 50% or more of the maximum viscosity are assessed as "○", and cases where the viscosity is less than 50% are assessed as "×". Furthermore, the viscosity was measured using a TVE-25 E-type viscometer manufactured by Toki Industries, Ltd., with the measurement temperature set to 25°C.

[0172] Evaluation of Polyimide Films [450 nm transmittance] The transmittance of the polyimide film at 450 nm was measured using a UV-Vis spectrophotometer / V-650DS (manufactured by Japan Spectrophotometer). For polyimide films whose thickness was not recorded in the examples and comparative examples, the film thickness was approximately 10 μm. For polyimide films whose thickness was recorded, the film thickness was as recorded.

[0173] [Yellow Degree (YI)] The b* (yellowness) of a 10 μm thick, 5 cm square polyimide film was measured using a UV-Vis spectrophotometer / V-650DS (manufactured by Japan Spectrophotometer) according to ASTM E313 standard. The light source was set to D65, and the viewing angle was set to 2°.

[0174] [Haze] The haze of the polyimide film was measured using a turbidimeter / NDH2000 (manufactured by Nippon Denshoku Kogyo) according to JIS K7136 standard.

[0175] [Coefficient of linear thermal expansion (CTE)] A polyimide film with a thickness of approximately 10 μm was cut into short strips with a width of 4 mm to serve as test pieces. Using a TMA / SS6100 (manufactured by Seiko Nanotech Co., Ltd.), the temperature was reduced from 400°C to 50°C with a clamping 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 determined based on the obtained TMA (thermomechanical analysis) curves.

[0176] [1% weight loss temperature] A polyimide film with a thickness of approximately 10 μm was used as a test piece. A calorimeter (Q5000IR) manufactured by TA Instruments was used to measure the temperature from 25°C to 600°C in a nitrogen atmosphere at a heating rate of 10°C / min. Based on the obtained weight curve, the weight at 150°C was set as 100%, and the temperature at which 1% weight loss occurred was calculated.

[0177] [Peel strength] The peel strength in the 90° direction was measured in atmospheric conditions at a tensile speed of 2 mm / min using a TENSILON RTA-500 manufactured by Orientec.

[0178] [Determination of Residual Stress] A 6-inch silicon wafer (625 μm thick, (100) substrate) was used as the reference substrate for evaluating the polyimide film. A polyimide precursor composition was coated onto the silicon wafer using a spin coater. The wafer was then thermally imidized directly from room temperature to the same temperature as in the examples and comparative examples under a nitrogen atmosphere (oxygen concentration below 200 ppm) to obtain a polyimide film / reference substrate laminate. The thickness of the polyimide film in the laminate was set to approximately 10 μm.

[0179] According to Japanese Patent No. 6798633, the radius of curvature of the obtained polyimide film / silicon wafer laminate was measured using an FLX-2320 manufactured by KLA Tencor at temperatures of 150°C, 140°C, 130°C, 120°C, and 110°C. The measurement was performed 20 times at each temperature, and the average value was calculated. Furthermore, the radius of curvature of the individual silicon wafer was also measured at the same temperature. Based on the obtained radius of curvature, the residual stress (S) at each temperature was calculated according to the following formula 1, and the residual stress at 23°C was obtained using a linear approximation based on the least squares method.

[0180] [Number 1]

[0181] in, E / (1-ν): Biaxial elastic modulus (Pa) of the substrate (reference substrate: silicon wafer). The Pa in (100) silicon is 1.805E11. h: Substrate thickness (m) t: Thickness of the polyimide film (m) R: Radius of curvature of the specimen (m) 1 / R = 1 / R² - 1 / R¹ R1: Radius of curvature of the substrate (silicon wafer) before film fabrication. R2: Radius of curvature after the membrane is made S: Average residual stress (Pa)

[0182] [Elastic modulus, elongation at break, tensile strength] A polyimide film with a thickness of about 10 μm was punched into a dumbbell shape according to the IEC450 standard as a test piece. The initial elastic modulus, elongation at break and tensile strength were determined using a TENSILON manufactured by ORIENTEC with a clamping length of 30 mm and a tensile speed of 2 mm / min.

[0183] <Raw materials> The abbreviations for the raw materials used in the following examples are as follows.

[0184] [Tetracarboxylic acid component] PMDA: Pyromellitic dianhydride DSDA: 3,3',4,4'-Diphenyltetracarboxylic acid dianhydride ODPA: 4,4'-O-diphthalic anhydride s-BPDA: 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride 6FDA: 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride

[0185] [Diamine component] 4-BAAB: 4-Aminobenzoic acid 4-aminophenyl ester BAPB:4,4'-bis(4-aminophenoxy)biphenyl 4,4-ODA: 4,4-Oxydiphenylamine

[0186] [Imidazole compounds] 2-Pz:2-Phenylidene Bz: Benzimidazole Im: Imidazole 1-Pz:1-Phenylidene

[0187] KBM-103: Phenylacetyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industries, Ltd.) KBM-202SS: Diphenyldimethoxysilane (manufactured by Shin-Etsu Chemical Industries, Ltd.) HIVAC-F-5: 1,3,5-Trimethyl-1,1,3,5,5-Pentaphenyltrisiloxane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.)

[0188] [solvent] NMP: N-methyl-2-pyrrolidone

[0189] Table 1-1 lists the tetracarboxylic acid and diamine components, and Table 1-2 lists the structural formulas of imidazole compounds.

[0190] [Table 1-1]

[0191] [Table 1-2]

[0192] [Table 1-3]

[0193] <Example 1> [Preparation of Polyimide Precursor Composition] 2.28 g (10 mmol) of 4-BAAB was placed in a nitrogen-purged reaction vessel, followed by 37.69 g of N-methyl-2-pyrrolidone, with a total added monomer mass (the sum of diamine and carboxylic acid components) of 12.5% ​​by mass. The mixture was stirred at room temperature for 1 hour. Then, 3.10 g (10 mmol) of ODPA was slowly added to the solution. The mixture was stirred at room temperature for 6 hours to obtain a homogeneous and viscous polyimide precursor composition. The viscosity stability of the polyimide precursor composition is shown in Table 2.

[0194] Manufacturing of polyimide film / substrate laminates A 6-inch Corning Eagle-XG (registered trademark) glass substrate (500 μm thick) was used as the glass substrate. A polyimide precursor composition was coated onto the glass substrate using a spin coater. Thermal imidization was then performed directly on the glass substrate under a nitrogen atmosphere (oxygen concentration below 200 ppm) by heating from room temperature to 420°C to obtain a polyimide film / substrate laminate. Peel strength was measured using 5 mm wide test samples made from the obtained polyimide film / glass laminate. Other film properties were assessed by immersing the laminate in water at 40°C (e.g., within the temperature range of 20°C to 100°C) to peel the polyimide film from the glass substrate. After drying, the properties of the polyimide film were evaluated. The polyimide film thickness was approximately 10 μm. The evaluation results are shown in Table 2.

[0195] <Examples 2-6, Comparative Examples 1-4> In Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 2, and a polyimide precursor composition was obtained in the same manner as in Example 1. Subsequently, a polyimide membrane was manufactured in the same manner as in Example 1, and the membrane properties were evaluated.

[0196] <Examples 7, 11, Comparative Examples 6-8> In Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 3, and the reaction was carried out in the same manner as in Example 1 to obtain a polyimide precursor composition. Except that the obtained polyimide precursor composition was used and the maximum heating temperature for amide maturation was changed to 450°C, a polyimide membrane was manufactured in the same manner as in Example 1, and the membrane properties were evaluated.

[0197] <Examples 8-10, Comparative Example 5> In Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratio) shown in Table 3, and the reaction was carried out in the same manner as in Example 1 to obtain a polyimide precursor solution. 2-Phenylidene, as an imidazole compound, was dissolved in 4 times its mass of N-methyl-2-pyrrolidone to obtain a homogeneous solution with a solid content of 20% by mass of 2-phenylimidazolium. The imidazole compound solution was mixed with the above-synthesized polyimide precursor solution in such a way that the amount of imidazole compound relative to the repeating unit 1 mole of the polyimide precursor was as described in Table 3, and the mixture was stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. Subsequently, a polyimide film was manufactured in the same manner as in Example 7, and the film properties were evaluated. However, regarding Comparative Example 5, the viscosity stability of the obtained polyimide precursor composition was poor, making it difficult to form a uniform polyimide film on the substrate, and therefore the film properties could not be evaluated.

[0198] <Examples 12-25, Comparative Examples 9 and 10> In Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 4 or 5, and the reaction was carried out in the same manner as in Example 1 to obtain a polyimide precursor solution. Instead of imidazole compounds, the compounds shown in Table 4 or 5 are used. The imidazole compound solution is mixed with the above-synthesized polyimide precursor solution in the amount recorded in Table 4 or 5, and stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. Subsequently, except that the maximum heating temperature for amide imidization was set to 420°C or 450°C (as described in Table 4 or 5), polyamide films were manufactured in the same manner as in Example 1, and the film properties were evaluated. Furthermore, regarding Comparative Example 9, no imidazole compound was added.

[0199] This application summarizes the embodiments of condition (i) and condition (ii) specified in Invention Series A, No. 1 as follows. (i)1~6, 7~11, 15~18, 19~25, 28 (ii)8~10, 12~18, 19~25, 26, 27, 28

[0200] [Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 acid dianhydride ODPA 100 80 60 50 50 50 40 20 50 s-BPDA 20 40 50 50 50 60 80 100 50 6FDA DSDA PMDA diamine 4-BAAB 100 100 100 100 80 80 100 100 100 60 BAPB 20 4,4-ODA 20 40 imidazole compounds 2-Pz Curing temperature / ℃ 420 420 420 420 420 420 420 420 420 420 Varnish evaluation viscosity stability ○ ○ ○ ○ ○ ○ ○ ○ ○ - Membrane evaluation Elastic modulus / GPa 8.5 9.1 8.8 9.3 7.1 7.0 9.5 9.2 9.3 6.2 Elongation at break / % 25 twenty three 27 twenty three 34 35 27 33 17 42 Fracture point strength / MPa 356 389 450 405 400 425 470 477 373 375 CTE / ppm·K-1 20 12 7 5 15 13 7 5 4 30 1% weight loss temperature / ℃ 520 522 524 525 526 525 527 529 533 519 450 nm transmittance / % 78 77 76 75 75 75 73 72 72 75 YI 9 10 11 12 12 12 15 16 16 12 Haze / % 0.3 0.2 0.2 0.3 0.5 0.5 0.2 0.2 0.2 1.3 Glass laminate evaluation Peel strength / gf·cm⁻¹ >400 >400 >400 >400 >400 >400 250 150 50 >400 Silicon wafer stack evaluation Residual stress / MPa 11 9 <4 <4 14 11 <4 <4 <4 25 SiO / SiN laminate evaluation Close contact test ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit).

[0201] [Table 3] Example 7 Example 8 Example 9 Example 10 Example 11 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 acid dianhydride ODPA 70 70 70 70 50 70 50 60 s-BPDA 30 30 30 30 30 30 10 70 6FDA 20 40 DSDA 30 PMDA 40 diamine 4-BAAB 100 100 100 100 100 100 100 100 100 BAPB 4,4-ODA imidazole compounds 2-Pz 0.025 0.1 0.5 1 Curing temperature / ℃ 450 450 450 450 450 450 450 450 Varnish Evaluation viscosity stability ○ ○ ○ ○ ○ × ○ ○ ○ Membrane evaluation Elastic modulus / GPa 9.4 8.1 7.6 6.9 8.2 - 5.8 8.3 6.1 Elongation at break / % 33 37 51 59 twenty two - 29 38 twenty two Fracture point strength / MPa 474 444 438 332 353 - 245 454 273 CTE / ppm·K-1 7 13 19 27 10 - 29 17 27 1% weight loss temperature / ℃ 527 529 529 524 512 - 499 521 504 450 nm transmittance / % 74 77 77 75 74 - 74 69 71 YI 13 10 10 12 13 14 20 18 Haze / % 0.3 0.3 0.3 0.3 0.5 1.2 0.4 0.7 Glass laminate evaluation Peel strength / gf·cm⁻¹ >400 >400 >400 >400 >400 - 50 >400 200 Silicon wafer stack evaluation Residual stress / MPa <4 10 12 20 7 - twenty three 18 twenty two SiO / SiN laminate evaluation Close contact test ○ ○ ○ ○ ○ - × ○ × The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit).

[0202] [Table 4] Example 12 Example 13 Comparative Example 9 Example 14 Example 15 Example 16 Example 17 Example 18 acid dianhydride ODPA 30 30 40 50 60 80 100 s-BPDA 100 70 70 60 50 40 20 6FDA DSDA PMDA diamine 4-BAAB 100 100 100 100 100 100 100 100 BAPB 4,4-ODA imidazole compounds 2-Pz 0.025 0.025 0.025 0.025 0.025 0.025 0.025 Bz lm 1-Pz Curing temperature / ℃ 420 420 420 420 420 420 420 420 Varnish Evaluation Viscosity stability ○ ○ ○ ○ ○ ○ ○ ○ Membrane evaluation Elastic modulus / GPa 8.9 8.6 9.7 9.3 9.2 9.1 8.9 7.4 Elongation at break / % 40 44 30 46 40 31 30 43 Fracture point strength / MPa 482 527 473 535 484 441 399 386 CTE / ppm·K-1 5 9 6 9 10 11 18 27 1% weight loss temperature / ℃ 544 531 529 529 528 527 525 523 450 nm transmittance / % 76 77 73 76 76 77 79 79 YI 12 12 15 12 11 10 8 8 Haze / % 0.4 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Glass laminate evaluation Peel strength / gf·cm⁻¹ 200 >400 >400 300 >400 >400 >400 >400 Silicon wafer stack evaluation Residual stress / MPa <4 6 <4 6 7 8 15 20 SiO / SiN laminate evaluation Close contact test ○ ○ ○ ○ ○ ○ ○ ○ The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit).

[0203] [Table 5] Example 19 Example 20 Comparative Example 10 Example 21 Example 22 Example 23 Example 24 Example 25 acid dianhydride ODPA 50 50 60 70 70 70 70 70 s-BPDA 50 30 30 30 30 30 30 6FDA 20 DSDA PMDA 40 diamine 4-BAAB 80 100 100 100 100 100 100 100 BAPB 4,4-ODA 20 imidazole compounds 2-Pz 0.025 0.025 0.025 Bz 0.025 lm 0.025 1-Pz 0.025 0.01 0.005 Curing temperature / ℃ 420 450 450 450 450 450 450 450 Varnish evaluation viscosity stability ○ ○ ○ ○ ○ ○ ○ ○ Membrane evaluation Elastic modulus / GPa 7.0 7.4 8.0 9.3 9.2 9.2 8.9 8.9 Elongation at break / % 57 46 50 35 42 39 41 40 Fracture point strength / MPa 494 382 469 444 482 479 510 507 CTE / ppm·K-1 twenty one twenty one 18 10 10 11 9 9 1% weight loss temperature / ℃ 526 513 521 529 529 529 529 528 450 nm transmittance / % 76 78 68 76 76 76 76 76 YI 11 9 twenty four 11 11 11 11 11 Haze / % 0.5 0.5 0.4 0.3 0.3 0.3 0.3 0.3 Glass laminate evaluation Peel strength / gf·cm⁻¹ >400 >400 >400 >400 >400 >400 >400 >400 Silicon wafer stack evaluation Residual stress / MPa 15 16 20 7 7 7 6 6 SiO / SiN laminate evaluation Close contact test ○ ○ ○ ○ ○ ○ ○ ○ The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit).

[0204] [Adhesion Test of Inorganic Thin Films after Formation] Using plasma CVD, SiOx and SiNx films of 400 nm each were sequentially deposited on the polyimide film surface of a polyimide film / substrate laminate manufactured in the same manner as in the Examples and Comparative Examples. Subsequently, the laminate was annealed in an annealing furnace at 430°C for 60 minutes. After removal from the annealing furnace, visual inspection was performed to observe delamination between the polyimide film and the glass substrate, and between the polyimide film and the SiOx film. Cases where no delamination was observed were rated as "○", and cases where delamination was observed in one of the two cases were rated as "×". The results are shown in Tables 2 to 5.

[0205] [Adhesion Test 2 of Inorganic Thin Film After Formation] Using plasma CVD, SiOx and SiNx films of 400 nm each were sequentially deposited on the polyimide film surface of a polyimide film / substrate laminate manufactured in the same manner as in the examples and comparative examples. Subsequently, the laminate was annealed in an annealing furnace at 430°C for 8 hours. After removal from the annealing furnace, visual inspection was performed to observe delamination between the polyimide film and the glass substrate, and between the polyimide film and the SiOx film. Cases where no delamination was observed were rated as "○", and cases where delamination was observed in one of them were rated as "×". The results are shown in Table 6.

[0206] [Table 6] Example 8 Example 26 Comparative Example 11 Example 27 Comparative Example 12 Example 24 Example 28 acid dianhydride ODPA 70 30 30 70 50 s-BPDA 30 100 100 70 70 30 50 6FDA DSDA PMDA diamine 4-BAAB 100 100 100 100 100 100 80 BAPB 4,4-ODA 20 imidazole compounds 2-Pz 0.025 0.025 0.025 0.025 1-Pz 0.01 Curing temperature / ℃ 450 450 450 450 450 450 450 SiO / SiN laminate evaluation Contact tightness test (430℃×8 h) ○ ○ × ○ × ○ ○ The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit).

[0207] Based on the above results, if the total ODPA and s-BPDA in the tetracarboxylic acid component is 70 mol% or more, and the ODPA ratio is 50 mol% or more, the peel strength exhibits an extremely high value exceeding 400 gf / cm, and a significant increase in 450 nm transmittance and a decrease in yellowness (YI) are observed. Furthermore, the addition of imidazole compounds is also confirmed to be effective in increasing 450 nm transmittance and reducing yellowness (YI). Moreover, if imidazole compounds are added at a concentration of 0.01 mol or more but less than 1 mol, when the total ODPA and s-BPDA in the tetracarboxylic acid component is 70 mol% or more (even if the ODPA ratio is less than 50 mol%), higher peel strength, higher 450 nm transmittance, and lower yellowness (YI) are confirmed.

[0208] [Examples of adding silane compounds] <Examples 29-34, 40-43, Reference Example 13> Similar to Example 7, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 7, and the reaction was carried out in the same manner as in Example 1 to obtain a polyimide precursor solution. The compounds shown in Table 7, which are silane compounds, were mixed with the above-synthesized polyimide precursor solution in the amounts shown in Table 7 (parts by mass relative to a total of 100 parts by mass of tetracarboxylic acid and diamine components). The mixture was stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. Except that the highest heating temperature for amide maturation was set to 450°C using the obtained polyimide precursor composition, a polyimide membrane was manufactured in the same manner as in Example 1, and the membrane properties were evaluated.

[0209] <Examples 35-39> Similar to Example 8, in Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 8. The reaction was carried out in the same manner as in Example 1 to obtain a polyimide precursor solution. The imidazole compound solution was then mixed with the polyimide precursor solution in the amount shown in Table 8. Regarding Examples 36-39, the compounds shown in Table 8 (as silane compounds) were mixed with the synthesized polyimide precursor solution in the amounts shown in Table 8 (parts by mass relative to a total of 100 parts by mass of the tetracarboxylic acid and diamine components). The mixture was stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. Except that the highest heating temperature for amide formation was set to 450°C using the obtained polyimide precursor composition, a polyimide membrane was manufactured in the same manner as in Example 1, and the membrane properties were evaluated. Furthermore, Example 35 did not add any silane compound for comparison, but otherwise had the same composition as Examples 36-39, although Example 35 is an example of this application.

[0210] <Examples 44-50> Similar to Examples 7 and 8, in Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 9. After obtaining a polyimide precursor solution, the reaction was carried out in the same manner as in Example 1. For Examples 47 and 48, the imidazole compound solution was mixed with the polyimide precursor solution in such a way that the amount of imidazole compound was the amount recorded in Table 9. For Examples 45, 46, and 48-50, the compounds shown in Table 9 as silane compounds were mixed with the above-synthesized polyimide precursor solution in the amount shown in Table 9 (parts by mass relative to a total of 100 parts by mass of the tetracarboxylic acid and diamine components), and stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. Except that the obtained polyimide precursor composition was used and the maximum heating temperature for amide imidization was set to 450°C, the polyimide film was manufactured in the same manner as in Example 1, and the film properties were evaluated. Furthermore, Examples 44 and 47 are examples for comparison without the addition of silane compounds, but they are examples of this application.

[0211] <Examples 51-53> Similar to Example 8, in Example 1, the tetracarboxylic acid and diamine components were changed to the compounds and amounts (molar ratios) shown in Table 10. The reaction was carried out in the same manner as in Example 1 to obtain a polyimide precursor solution. The imidazole compound solution was then mixed with the polyimide precursor solution in the amount shown in Table 10. Regarding Examples 52 and 53, the compounds shown in Table 10 (as silane compounds) were mixed with the synthesized polyimide precursor solution in the amounts shown in Table 10 (parts by mass relative to a total of 100 parts by mass of the tetracarboxylic acid and diamine components). The mixture was stirred at room temperature for 3 hours to obtain a homogeneous and viscous polyimide precursor composition. Except that the highest heating temperature for amide formation was set to 450°C using the obtained polyimide precursor composition, a polyimide membrane was manufactured in the same manner as in Example 1, and the membrane properties were evaluated. Furthermore, Example 51 is a comparative example without the addition of a silane compound, but it is an example of this application.

[0212] For Examples 51-53, the peel strength test of the glass laminate and the determination of residual stress in the silicon wafer laminate were performed in the same manner as in Example 1. Furthermore, the peel between the polyimide film and the glass substrate, and between the polyimide film and the SiOx film, were observed in the same manner as in the above-described [adhesion test 2 after inorganic thin film formation]. The measurement and evaluation results are shown in Table 10.

[0213] [Table 7] Example 29 Example 30 Example 31 Example 32 Example 33 Example 34 Example 40 Example 41 Example 42 Example 43 See Example 13 acid dianhydride ODPA 70 70 70 70 70 70 70 70 70 70 70 s-BPDA 30 30 30 30 30 30 30 30 30 30 30<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ 4,4-ODA imidazole compounds 2-Pz silane compounds KBM-103 0.5 2 5 10 20 30 KBM-202SS 0.5 2 5 10 HIVAC-F-5 10 Curing temperature / ℃ 450 450 450 450 450 450 450 450 450 450 450 Varnish evaluation viscosity stability ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Membrane evaluation Elastic modulus / GPa 9.1 9.0 8.6 8.2 7.9 7.5 8.8 8.8 8.2 7.9 7.6 Elongation at break / % 38 32 39 37 29 35 36 31 33 32 32 Fracture point strength / MPa 510 460 501 464 375 367 470 442 446 414 377 CTE / ppm·K-1 9 8 11 10 15 twenty one 8 7 8 9 11 1 wt% temperature loss per ℃ 530 529 531 530 527 524 527 526 522 521 487 450 nm transmittance / % 75 76 77 78 80 80 75 76 76 77 76 YI 12 11 11 10 10 10 12 11 12 11 12 Haze / % 0.4 0.3 0.4 0.4 0.4 0.4 0.4 0.4 0.3 0.4 0.4 The content of the silane compound is in parts by mass relative to 100 parts by mass of the total tetracarboxylic dianhydride and diamine.

[0214] [Table 8] Example 35 Example 36 Example 37 Example 38 Example 39 acid dianhydride ODPA 70 70 70 70 70 s-BPDA 30 30 30 30 30 6FDA DSDA PMDA diamine 4-BAAB 100 100 100 100 100 BAPB 4,4-ODA imidazole compounds 2-Pz 0.01 0.01 0.01 0.01 0.01 silane compounds KBM-103 2 5 10 20 KBM-202SS HIVAC-F-5 Curing temperature / ℃ 450 450 450 450 450 Varnish Evaluation viscosity stability ○ ○ ○ ○ ○ Membrane evaluation Elastic modulus / GPa 8.7 9.4 9.4 8.9 8.4 Elongation at break / % 36 33 36 38 31 Fracture point strength / MPa 476 455 494 460 407 CTE / ppm·K-1 8 10 10 12 12 1 wt% temperature loss per ℃ 531 531 531 534 532 450 nm transmittance / % 75 76 77 78 78 YI 11 11 10 10 9 Haze / % 0.3 0.4 0.4 0.4 0.4 The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit). The content of the silane compound is in parts by mass relative to 100 parts by mass of the total tetracarboxylic dianhydride and diamine.

[0215] [Table 9] Example 44 Example 45 Example 46 Example 47 Example 48 Example 49 Example 50 acid dianhydride ODPA 60 60 60 60 60 50 50 s-BPDA 40 40 40 40 40 50 30 6FDA 20 DSDA PMDA diamine 4-BAAB 100 100 100 100 100 80 100 BAPB 4,4-ODA 20 imidazole compounds 2-Pz 0.015 0.015 silane compounds KBM-103 5 10 10 20 20 KBM-202SS HIVAC-F-5 Curing temperature / ℃ 450 450 450 450 450 420 450 Varnish evaluation viscosity stability ○ ○ ○ ○ ○ ○ ○ Membrane evaluation Elastic modulus / GPa 8.7 8.5 8.2 8.5 7.9 6.0 7.2 Elongation at break / % 30 35 42 33 45 45 35 Fracture point strength / MPa 450 445 435 447 452 413 332 CTE / ppm·K-1 8 10 14 11 16 18 15 1 wt% temperature loss per ℃ 530 530 530 532 532 523 512 450 nm transmittance / % 72 74 75 77 77 77 76 YI 16 14 14 12 12 10 11 Haze / % 0.3 0.3 0.3 0.3 0.3 0.3 0.3 The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit). The content of the silane compound is in parts by mass relative to 100 parts by mass of the total tetracarboxylic dianhydride and diamine.

[0216] [Table 10] Example 51 Example 52 Example 53 acid dianhydride ODPA 50 50 50 s-BPDA 50 50 50 6FDA DSDA PMDA diamine 4-BAAB 100 100 100 BAPB 4,4-ODA imidazole compounds 2-Pz 0.025 0.025 0.025 silane compounds KBM-103 30 50 KBM-202SS HIVAC-F-5 Curing temperature / ℃ 450 450 450 Varnish Evaluation Viscosity stability ○ ○ ○ Membrane Evaluation Elastic modulus / GPa 8.2 6.6 5.8 Elongation at break / % 36 27 32 Fracture point strength / MPa 456 311 302 CTE / ppm·K-1 10 17 twenty four 1 wt% temperature loss per ℃ 535 532 530 450 nm transmittance / % 76 81 83 YI 12 10 8 Haze / % 0.3 0.3 0.3 Glass laminate evaluation Peel strength / gf·cm⁻¹ >400 >400 >400 Silicon wafer stack evaluation Residual stress / MPa 11 16 18 SiO / SiN laminate evaluation Contact tightness test (430℃×8 h) ○ ○ ○ The unit of measurement for imidazole compounds is eq (the number of moles per mole repeat unit). The content of the silane compound is in parts by mass relative to 100 parts by mass of the total tetracarboxylic dianhydride and diamine.

[0217] Referring to Table 7, compared with Example 7, the transmittance at 450 nm was further improved in the examples with added silane compounds (KBM-103 and KBM-202SS). In Reference Example 13, the transmittance at 450 nm was also improved, but the 1% weight loss temperature decreased significantly, indicating poor heat resistance. Referring to Table 8, the improvement in transmittance at 450 nm was also confirmed by adding silane compounds in the system with added imidazole compounds. The same trend was also observed in Tables 9 and 10. [Industrial Applicability]

[0218] This invention can be appropriately applied to the manufacture of flexible electronic devices, such as liquid crystal displays, organic EL displays and other flexible displays, electronic paper and other display devices, solar cells and CMOS and other light-receiving devices.

Claims

1. A polyimide precursor composition comprising a polyimide precursor with repeating units represented by the following general formula (I), and a Si-ORa structure present in an amount exceeding 0 parts by mass and less than 60 parts by mass relative to the total amount of tetracarboxylic dianhydride and diamine compound in the manufacture of the above-mentioned polyimide precursor composition (wherein, Ra is a silane compound (where Ra is a hydrogen atom or a hydrocarbon group), and at least one imidazole compound present in an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 mol of the above-mentioned polyimide precursor, [Chemical 1] (in general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, R1 and R2 are independently hydrogen atoms, alkyl groups having 1 to 6 carbon atoms or alkylsilyl groups having 3 to 9 carbon atoms, wherein X1 satisfies (ii), (ii) contains 70 mol% or more of the structure represented by formula (1-1) and / or the structure represented by formula (1-2), [Chemical 2] Y1 contains 70 mol% or more of the structure represented by formula (B); [Chemical 3]).

2. The polyimide precursor composition of claim 1, wherein 60 mol% or more of X1 has a structure represented by formula (1-1).

3. The polyimide precursor composition of claim 1, wherein 80 mol% or more of Y1 is of the structure represented by formula (B).

4. The polyimide precursor composition of claim 1, wherein it further contains at least one imidazole compound in an amount of 0.01 mol or more but less than 1 mol relative to the repeating unit 1 of the polyimide precursor.

5. The polyimide precursor composition of claim 4, wherein the imidazole compound is selected from at least one of the group consisting of 1,2-dimethylimidazolium, 1-methylimidazolium, 2-methylimidazolium, 2-phenylimidazolium, 1-phenylimidazolium, imidazolium and benzimidazole.

6. The polyimide precursor composition of claim 1, wherein the silane compound is a compound represented by the following formula: (RaO)nSi(Rb)4-n (where n is an integer from 1 to 4, Ra is a hydrogen atom or a straight-chain or branched alkyl group having 1 to 8 carbon atoms, and Rb is an alkyl or aryl group having 10 or fewer carbon atoms).

7. A polyimide film obtained from the polyimide precursor composition of claim 1.

8. A polyimide film / substrate laminate, characterized in that it comprises: a polyimide film obtained from the polyimide precursor composition of claim 1, and a substrate.

9. The laminate of claim 8, wherein an inorganic thin film layer is further provided on the polyimide film of the laminate.

10. The laminate as claimed in claim 8 or 9, wherein the substrate is a glass substrate.

11. A method for manufacturing a polyimide film / substrate laminate, comprising the following steps: (a) applying the polyimide precursor composition as claimed in claim 1 onto a substrate; and (b) subjecting the polyimide precursor to heat treatment on the substrate to deposit a polyimide film on the substrate.

12. A method for manufacturing a laminate as claimed in claim 11, wherein after step (b) above, the method further includes the following step: (c) forming an inorganic thin film layer on the polyimide film of the laminate.

13. A method for manufacturing a flexible electronic device, comprising the following steps: (d) On the inorganic thin film layer of the laminate manufactured in claim 10, at least one layer selected from a conductive layer and a semiconductor layer is formed; and (e) The substrate is peeled off from the polyimide film.

14. A flexible electronic device comprising a polyimide film as claimed in claim 7.

15. A flexible electronic device substrate comprising a polyimide film as claimed in claim 7.

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