Polyimide precursor, polyimide, polyimide film, flexible electronic device, and method for producing the same

Abstract

A flexible electronic device is provided that includes a polyimide film exhibiting excellent CV characteristics. The polyimide film is formed from a polyimide that exhibits a maximum gradient of 0.005 / V or more when a laminate formed to a thickness of 0.75 μm on a silicon wafer with a resistivity of 4 Ωcm is subjected to capacitance-voltage measurements. (Note that the maximum gradient refers to the maximum absolute value of the gradient in a normalized capacitance-voltage curve during the third positive scan, when capacitance measurements are performed while applying a DC voltage to the polyimide film relative to the silicon wafer between a minimum voltage V1 and a maximum voltage V2, with the capacitance at the minimum voltage V1 being normalized as 1.)

Description

[Technical Field]

[0001] The present invention relates to a polyimide that is suitable for use in electronic devices, such as substrates for flexible devices, and further to a polyimide film, a laminate containing the polyimide film, and an electronic device containing the polyimide or the laminate. [Background technology]

[0002] Glass has traditionally been used as a substrate for displays such as liquid crystal displays and organic electroluminescence (EL) displays. However, when glass is thinned to reduce weight, it lacks strength and becomes fragile. Therefore, lightweight and flexible plastic substrates have been proposed as an alternative to glass substrates. In displays such as liquid crystal displays and EL displays, semiconductor elements such as TFTs are formed on the substrate to drive each pixel. Therefore, the substrate must have heat resistance and dimensional stability. Polyimide film is expected to be a promising substrate for displays because of its excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability.

[0003] Regarding TFT elements formed on polyimide substrates, Non-Patent Documents 1 and 2 report that positive carriers are induced by negative charges present at the interface of the polyimide substrate, which affects the TFT characteristics. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Junehwan Kim et al., “High Performance Reliebility LTPS Technology for AdvancedFlexible Mobile Applications”, IDW / AD'16, pp.1356-1359 (2016) [Non-patent document 2] Yi-Da Ho et al., “AbnormalVth Degradation Behavior of the Polycrystalline Silicon Thin-Film Transistorson the Polyimide Substrate”, IDW'17, pp. 1508-1511 (2017) Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, Non-Patent Documents 1 and 2 report the influence of polyimide interfaces on TFT characteristics, but do not specifically evaluate the interface state density where negative charges can exist. Furthermore, there is no detailed description of polyimides, and there is no data on evaluating TFT characteristics by changing the polyimide substrate, so information on polyimides suitable for substrates is also unclear.

[0006] One method for evaluating the state density on the surface of insulating films such as polyimide is to measure the capacitance-voltage characteristics (hereinafter referred to as CV characteristics). It is generally known that the shape of the CV curve obtained by evaluating the voltage dependence of the capacitance of a semiconductor-insulating film-metal (electrode) capacitor changes depending on the state density present at the semiconductor-insulating film interface. Therefore, it is necessary to evaluate the CV characteristics that affect device characteristics such as TFT characteristics, and to provide polyimide films that are optimal as substrates for semiconductor devices and electronic devices, including displays, as well as to further expand the applications of polyimide.

[0007] An object of the present invention is to provide a polyimide exhibiting excellent CV characteristics, particularly a polyimide in the form of a film, a laminate substrate using the polyimide, and an electronic device such as a flexible display including the same. [Means for solving the problem]

[0008] The present invention relates to the following.

[0009] 1. A polyimide film for flexible electronic devices formed from a polyimide that exhibits a maximum gradient of 0.005 / V or more when capacitance-voltage measurements are performed on a laminate formed of a 0.75 μm-thick polyimide film on a silicon wafer with a resistivity of 4 Ωcm. (The maximum gradient refers to the maximum absolute value of the gradient in a normalized capacitance-voltage curve during the third positive scan, when capacitance measurements are performed while applying a DC voltage between a minimum voltage V1 and a maximum voltage V2 to the polyimide film relative to the silicon wafer, with the DC voltage being scanned in a positive direction from the minimum voltage V1 to the maximum voltage V2 and in a negative direction from the maximum voltage V2 to the minimum voltage V1. Here, the minimum voltage V1 is the voltage at which the capacitance of the polyimide film alone is observed, and the normalized capacitance-voltage curve is normalized such that the capacitance at the minimum voltage V1 is set to 1.)

[0010] 2. A polyimide film for flexible electronic devices according to item 1, wherein the weight fraction of imide groups (-CONCO-) in the polyimide repeating units is less than 38.3 wt %.

[0011] 3. A polyimide film for flexible electronic devices according to item 1 or 2 above, characterized in that the concentration of amine terminal groups in the entire polyimide calculated from the charge ratio is 29 μmol / g or less.

[0012] 4. A tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic dianhydride; (B-1) at least one diamine selected from 1,4-diaminobenzene, [1,1':4',1"-terphenyl]-4,4"-diamine, and 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, and (B-2) At least one diamine selected from 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine and a diamine component (B) containing (However, when the diamine component (B) contains 1,4-diaminobenzene and 9,9-bis(4-aminophenyl)fluorene), the amount of diamine compounds other than the diamine (B-1) and the diamine (B-2) is 20 mol % or less.)

[0013] 5. The polyimide precursor according to item 4, wherein the diamine component (B) contains the diamine (B-1) and the diamine (B-2) in a total amount of 40 mol % or more.

[0014] 6. The polyimide precursor according to 4 above, wherein the sum of the repeating units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and the diamine (B-1) and the repeating units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and the diamine (B-2) is 40 mol % or more.

[0015] 7. A polyimide obtained by imidizing the polyimide precursor according to any one of items 4 to 6 above.

[0016] 8. A polyimide film in the form of a film of the polyimide according to item 7 above.

[0017] 9. A flexible electronic device comprising the polyimide film according to any one of claims 1 to 3. 10. A flexible electronic device according to item 9, wherein the polyimide film is the polyimide film according to claim 8.

[0018] 11. A method for producing a flexible electronic device according to item 9 or 10, comprising: The method includes a step of applying a polyimide precursor solution or a polyimide precursor solution composition onto a carrier substrate and imidizing the solution to form a laminate having the carrier substrate and a polyimide film. A manufacturing method characterized by:

[0019] In addition to the above, the present application also discloses at least the following:

[0020] 1. A polyimide characterized by exhibiting a maximum gradient of 0.005 / V or more when capacitance-voltage measurements are performed on a laminate formed of a 0.75 μm-thick polyimide film on a silicon wafer having a resistivity of 4 Ωcm. (The maximum gradient refers to the maximum absolute value of the gradient in a normalized capacitance-voltage curve during the third positive scan, when capacitance measurements are performed while applying a DC voltage between a minimum voltage V1 and a maximum voltage V2 to the polyimide film relative to the silicon wafer, with the DC voltage being scanned in a positive direction from the minimum voltage V1 to the maximum voltage V2 and in a negative direction from the maximum voltage V2 to the minimum voltage V1. Here, the minimum voltage V1 is the voltage at which the capacitance of the polyimide film alone is observed, and the normalized capacitance-voltage curve is normalized such that the capacitance at the minimum voltage V1 is set to 1.)

[0021] 2. The polyimide according to item 1, wherein the weight fraction of imide groups (-CONCO-) in the repeating units of the polyimide is less than 38.3 wt %.

[0022] 3. The polyimide according to item 1 or 2, wherein the concentration of amine terminal groups in the entire polyimide calculated from the charge ratio is 29 μmol / g or less.

[0023] 4. A tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic dianhydride; (B-1) at least one diamine selected from 1,4-diaminobenzene, [1,1':4',1"-terphenyl]-4,4"-diamine, and 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, and (B-2) At least one diamine selected from 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine and a diamine component (B) containing A polyimide precursor comprising a repeating unit obtained by reacting

[0024] 5. The polyimide precursor according to item 4, wherein the diamine component (B) contains the diamine (B-1) and the diamine (B-2) in a total amount of 40 mol % or more.

[0025] 6. The polyimide precursor according to item 4, wherein the sum of the repeating units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and the diamine (B-1) and the repeating units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and the diamine (B-2) is 40 mol % or more.

[0026] 7. A polyimide obtained by imidizing the polyimide precursor according to any one of items 4 to 6 above.

[0027] 8. A polyimide precursor solution that provides the polyimide according to any one of items 1 to 3 above.

[0028] 9. A polyimide solution which provides the polyimide according to any one of items 1 to 3 above.

[0029] 10. A method for producing a polyimide solution, comprising imidizing the polyimide precursor solution according to item 8 above.

[0030] 11. A polyimide film in the form of a film of the polyimide according to any one of items 1 to 3 and 7 above.

[0031] 12. A laminate comprising a substrate and the polyimide film of item 11 above.

[0032] 13. A substrate comprising the polyimide film of item 11 above, used in electronic devices.

[0033] 14. An electronic device comprising the polyimide film of item 11, the laminate of item 12, or the substrate of item 13.

[0034] 15. An electronic device comprising a semiconductor layer formed on the polyimide film of item 11, the laminate of item 12, or the substrate of item 13. [Effects of the Invention]

[0035] According to the present invention, it is possible to provide a polyimide exhibiting excellent CV characteristics, particularly a polyimide in the form of a film, a laminate substrate using the polyimide, and an electronic device, particularly a flexible electronic device, including the same, such as a flexible display.

[0036] Since the polyimide film of the present invention has excellent CV characteristics, even when used as a substrate for semiconductor elements such as TFTs, there is little concern that the performance of the semiconductor elements will be affected, and there is also little concern that the element characteristics will change or deteriorate, such as a shift in switching characteristics, over long periods of use. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a schematic diagram of a system for measuring the CV characteristics of polyimide. [Figure 2] FIG. 10 is a diagram for explaining a method for obtaining a maximum gradient from a CV characteristic. DETAILED DESCRIPTION OF THE INVENTION

[0038] <<C-V Characteristics>> First, the measurement method and definition of the C-V characteristics related to polyimide will be described. Fig. 1 shows a schematic diagram of the C-V measurement system. A polyimide film 2 is formed on the surface of a silicon wafer 1 to serve as a measurement sample. Mercury is brought into contact with a predetermined area on the surface of the polyimide film 2 to form a mercury electrode 3. A DC voltage is applied between the silicon wafer 1 (ground potential) and the mercury electrode 3 by a DC power supply 4, and the capacitance (capacitance) at that DC voltage is measured by applying an AC voltage with a predetermined frequency and amplitude by an AC power supply 5. In the present application, a forward scan (raising the DC voltage) and a reverse scan (lowering the DC voltage) are performed between the minimum voltage V1 and the maximum voltage V2 of the DC voltage range, and the capacitance is measured during that time. The "maximum gradient" described later is obtained based on the data of the C-V measurement during the third forward scan.

[0039] As the minimum voltage V1 of the DC voltage range, when the silicon wafer is of p-type, a sufficient negative bias voltage is applied so that the capacitance of only the polyimide film is exhibited. In the embodiment of the present invention, it is set to -40V, but depending on the properties of the polyimide film, a lower voltage (a voltage with a larger absolute value of negative) may be required. The maximum voltage V2 of the DC voltage range is sufficiently higher than the voltage at which the maximum gradient described later is observed, and is also sufficiently high so that the maximum gradient is observed even in the reverse scan. Also, both the absolute value of the minimum voltage V1 and the maximum voltage V2 are set widely within the range below the breakdown voltage of the polyimide film and within the range allowed by the capabilities of the device. In the embodiment of the present invention, the scanning range is -40V to 40V.

[0040] The scanning speed of the DC voltage is, for example, in the range of 10 mV / sec to 100 V / sec, and can be selected from this range in consideration of the purpose of measurement. Practically, a scanning speed is adopted from the range of 0.05 V / sec to 2 V / sec, for example, from the range of 0.1 V / sec to 0.5 V / sec, and the reproducibility is good. In the embodiment of the present invention, 0.25 V / sec and 0.18 V / sec are adopted. As will be described later, it has been confirmed that there is no difference due to the difference in these two scanning speeds.

[0041] The AC voltage (sine wave) used for capacitance measurement can be varied depending on the application of the polyimide film (i.e., to suit the frequency range of interest). For display applications, measurements can be performed at frequencies ranging from 100 Hz to 1 MHz, particularly 500 Hz to 10 kHz. In the examples of the present invention, a frequency of 2.5 kHz was used. The amplitude can be selected as needed, as long as it is sufficiently smaller than the DC voltage, but in the examples of the present invention, a voltage of 0.1 V was used.

[0042] In the present invention, when evaluating the results of CV measurement, the capacitance value at the minimum voltage V1 is set to 1, and the properties of the polyimide are evaluated based on a normalized capacitance-voltage curve (normalized CV curve) obtained by normalizing the measured CV curve. This is to evaluate factors that affect semiconductors, such as interface states, while excluding differences in capacitance due to errors in the polyimide film thickness and differences in dielectric constant, etc. In order to minimize evaluation errors, the thickness of the polyimide film to be measured is preferably targeted at 0.65 μm to 0.85 μm, and particularly 0.75 μm, in the evaluation of the present invention.

[0043] In such a measurement system, when the DC voltage is scanned in the positive direction from the minimum voltage V1 to the maximum voltage V2 (this is the third positive scan), as shown in Figure 2, typically, after the initial flat region, a first decreasing region where the capacitance decreases relatively significantly appears, followed by a relatively flat region. Next, when the voltage is scanned in the negative direction from the maximum voltage V2 to the minimum voltage V1, the above regions are typically observed in the reverse order to that observed in the positive scan. However, this curve does not match the curve of the positive scan, and hysteresis is often observed.

[0044] The "first decrease region" described above is understood to be the process in which the vicinity of the interface in the silicon wafer changes from a majority carrier accumulation layer to a depletion layer, and the depletion layer expands. In this invention, the maximum gradient (maximum negative absolute value) in the first decrease region is defined as the "maximum gradient." Therefore, the "maximum gradient" can be obtained as the absolute value of the apex of the negative peak that appears in the differential curve of the normalized CV curve.

[0045] The polyimide of the present invention has a "maximum gradient" of 0.005 / V or more, preferably greater than 0.007 / V, as measured by the above-described CV measurement for a 0.75 μm-thick film formed on a silicon wafer with a resistivity of 4 Ωcm. The smaller the interface state density, the larger (larger absolute value) the maximum gradient. The surface state of the polyimide (e.g., composition, functional groups (especially surface functional groups), presence of impurities or additives, etc.) is thought to affect the interface state density. However, in the present invention, the surface state of the polyimide at the interface with the semiconductor is extremely favorable, so it can be assumed to have a large "maximum gradient." Because of this large "maximum gradient," even when the polyimide of the present invention is used in electronic devices such as displays, there is little adverse effect on the operation and durability of the electronic devices.

[0046] The development of polyimides that focus on such CV characteristics has not been reported or actually undertaken. Naturally, existing polyimides do not satisfy the above-mentioned CV characteristics. Furthermore, since the CV characteristics are thought to be affected by the surface condition of the polyimide, the chemical structure of the polyimide does not matter as long as the CV characteristics are satisfied.

[0047] <<Polyimide, polyimide precursor>> The polyimide or its precursor (polyimide precursor) of the present invention is not particularly limited in chemical structure as long as it satisfies the CV characteristics, and the chemical structure may be appropriately selected depending on the function to be imparted. The polyimide precursor is a compound represented by the following general formula I:

[0048] [ka] (In general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, and R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.) Particularly preferred is a polyamic acid in which R1 and R2 are hydrogen atoms. Partially imidized polymers, i.e., polymers containing repeating units in which at least one of the two amide structures in formula I is imidized, are also included in the terms "polyimide precursor" and "polyamic acid" (in which the remaining R1 and R2 are hydrogen atoms).

[0049] The polyimide may also be represented by the following general formula II:

[0050] [ka] (In the formula, X1 is a tetravalent aliphatic or aromatic group, and Y1 is a divalent aliphatic or aromatic group.) It has a repeating unit represented by the following formula:

[0051] The chemical structure of such a polyimide will be explained below in terms of the structures of X1 and Y2 in the repeating unit (general formula (II)) and the monomers (tetracarboxylic acid component, diamine component, and other components) used in the production, followed by an explanation of the production method.

[0052] In this specification, the tetracarboxylic acid component includes tetracarboxylic acids, tetracarboxylic acid dianhydrides, and other tetracarboxylic acid derivatives such as tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides, which are used as raw materials for producing polyimides. Although not particularly limited, it is convenient to use tetracarboxylic acid dianhydrides in production, and the following description will discuss an example in which tetracarboxylic acid dianhydrides are used as the tetracarboxylic acid component. Furthermore, the diamine component is a diamine compound having two amino groups (-NH2), which is used as a raw material for producing polyimides.

[0053] In addition, in this specification, the polyimide film means both a film formed on a substrate and in a laminated state, and a film without a substrate supporting the film (including a self-supporting film). When used as a substrate, the polyimide of the present invention is preferably in the form of a film. Further, the polyimide of the present invention may be in the form of a layer discretely present on a supporting substrate or a layer formed of a different material.

[0054] <<Structure and Monomer in the Repeating Unit>> <X1 and Tetracarboxylic Acid Component>

[0055] As the tetravalent group having an aromatic ring of X1, a tetravalent group having an aromatic ring with 6 to 40 carbon atoms is preferable.

[0056] Examples of the tetravalent group having an aromatic ring include the following.

[0057] [Chemical formula] (In the formula, Z1 is a direct bond or the following divalent group:

[0058] [Chemical formula] One of them. However, Z2 in the formula is a divalent organic group, and Z3 and Z4 are each independently an amide bond, an ester bond, or a carbonyl bond, and Z5 is an organic group containing an aromatic ring.)

[0059] Specific examples of Z2 include an aliphatic hydrocarbon group having 2 to 24 carbon atoms and an aromatic hydrocarbon group having 6 to 24 carbon atoms.

[0060] Specific examples of Z5 include an aromatic hydrocarbon group having 6 to 24 carbon atoms.

[0061] As the tetravalent group having an aromatic ring, the following are particularly preferable because they can achieve both high heat resistance and high transparency of the obtained polyimide material.

[0062] [ka] (wherein Z1 is a direct bond or a hexafluoroisopropylidene bond.)

[0063] Here, Z1 is more preferably a direct bond, since this allows the resulting polyimide material to have high heat resistance, high transparency, and a low coefficient of linear thermal expansion.

[0064] Additionally, preferred groups include those in which Z1 in the above formula (9) is the following formula (3A):

[0065] [ka] Examples of such compounds include compounds having a fluorenyl-containing group represented by the formula: Z 11 and Z 12 are each independently, preferably the same, a single bond or a divalent organic group. 11 and Z 12 As the group, an organic group containing an aromatic ring is preferable, and for example, a group represented by the formula (3A1):

[0066] [ka] (Z 13 and Z 14 are, independently of one another, a single bond, -COO-, -OCO- or -O-, where Z 14 When attached to a fluorenyl group, Z 13 -COO-, -OCO- or -O- with Z 14 is preferably a single bond; R 91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably methyl, and n is an integer of 0 to 4, preferably 1. The structure represented by

[0067] Examples of tetracarboxylic acid components that provide repeating units of general formula (II) in which X1 is a tetravalent group having an aromatic ring include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, pyromellitic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 4,4'-oxydiphthalic acid, bis(3,4-dicarboxyphenyl)sulfone, m-terphenyl-3,4,3',4'-tetracarboxylic acid, p-terphenyl-3,4,3',4'-tetracarboxylic acid, biscarboxyphenyldimethylsilane, bisdicarboxyphenoxydiphenyl sulfide, and sulfonyldiphthalic acid, and these dianhydrides are preferably used as monomers. An example of a tetracarboxylic acid component that provides a repeating unit of general formula (II) in which X1 is a tetravalent group having an aromatic ring containing a fluorine atom is 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride. Another preferred compound is (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate). The tetracarboxylic acid component may be used alone or in combination.

[0068] The tetravalent group having an alicyclic structure of X1 is preferably a tetravalent group having an alicyclic structure with 4 to 40 carbon atoms, and more preferably has at least one 4- to 12-membered aliphatic ring, more preferably a 4-membered or 6-membered aliphatic ring. Preferred tetravalent groups having a 4-membered or 6-membered aliphatic ring include the following:

[0069] [ka] (In the formula, R 31 ~R 38are each independently a direct bond or a divalent organic group. 41 ~R 47 R each independently represents one selected from the group consisting of groups represented by the formula: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-. 48 is an organic group containing an aromatic ring or an alicyclic structure.

[0070] R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 , R 38 Specific examples of the bond include a direct bond, an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an oxygen atom (—O—), a sulfur atom (—S—), a carbonyl bond, an ester bond, and an amide bond.

[0071] R 48 Examples of the organic group containing an aromatic ring include the following:

[0072] [ka] (Wherein, W1 is a direct bond or a divalent organic group, n 11 ~n 13 each independently represents an integer of 0 to 4, and R 51 , R 52 , R 53 are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group.

[0073] Specific examples of W1 include a direct bond, a divalent group represented by the following formula (5), and a divalent group represented by the following formula (6).

[0074] [ka] (R in Equation (6) 61 ~R 68each independently represents a direct bond or a divalent group represented by the formula (5).

[0075] As the tetravalent group having an alicyclic structure, the following are particularly preferred, since they can provide the resulting polyimide with high heat resistance, high transparency, and a low coefficient of linear thermal expansion.

[0076] [ka]

[0077] Examples of tetracarboxylic acid components that provide repeating units of formula (II) in which X1 is a tetravalent group having an alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic acid, isopropylidenediphenoxybisphthalic 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), octahydropentalene-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, and derivatives thereof such as tetracarboxylic dianhydrides, tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides. The tetracarboxylic acid component may be used alone or in combination of multiple types.

[0078] <Y1 and diamine component> As the divalent group having an aromatic ring of Y1, a divalent group having an aromatic ring with 6 to 40 carbon atoms, more preferably 6 to 20 carbon atoms, is preferred.

[0079] Examples of the divalent group having an aromatic ring include the following.

[0080] [Chemical formula] (In the formula, W1 is a direct bond or a divalent organic group, and n 11 ~n 13 each independently represents an integer of 0 to 4, and R 51 , R 52 , R 53 are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group.)

[0081] Specific examples of W1 include a direct bond, a divalent group represented by the following formula (5), and a divalent group represented by the following formula (6).

[0082] [Chemical formula]

[0083] [ka] (R in Equation (6) 61 ~R 68 each independently represents a direct bond or a divalent group represented by the formula (5).

[0084] Here, it is particularly preferable that W1 is one selected from the group consisting of a direct bond or a group represented by the formula: -NHCO-, -CONH-, -COO-, and -OCO-, since this allows the obtained polyimide to have high heat resistance, high transparency, and a low linear thermal expansion coefficient at the same time. 61 ~R 68 It is also particularly preferred that is either a direct bond or a divalent group represented by the formula (6), which is one selected from the group consisting of groups represented by the formulas: -NHCO-, -CONH-, -COO-, and -OCO-.

[0085] Additionally, preferred groups include those in which W1 in the above formula (4) is the following formula (3B):

[0086] [ka] Examples of such compounds include compounds having a fluorenyl-containing group represented by the formula: Z 11 and Z 12 are each independently, preferably the same, a single bond or a divalent organic group. 11 and Z 12 As the group, an organic group containing an aromatic ring is preferable, for example, a group represented by the formula (3B1):

[0087] [ka] (Z 13 and Z 14 are, independently of one another, a single bond, -COO-, -OCO- or -O-, where Z 14 When attached to a fluorenyl group, Z 13 -COO-, -OCO- or -O- with Z 14is preferably a single bond; R 91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably phenyl, and n is an integer of 0 to 4, preferably 1. The structure represented by

[0088] Another preferred group is a compound in which W1 in the above formula (4) is a phenylene group, that is, a terphenyldiamine compound, and particularly preferred is a compound in which all bonds are para-bonded.

[0089] Another preferred group is a group in which W1 in the above formula (4) is R 61 and R 62 is a 2,2-propylidene group.

[0090] Yet another preferred group is one in which W1 in the above formula (4) is represented by the following formula (3B2):

[0091] [ka] Examples of the compound include compounds represented by the following formula:

[0092] Examples of diamine components that provide repeating units of general formula (II) in which Y1 is a divalent group having an aromatic ring include p-phenylenediamine, m-phenylenediamine, benzidine, 3,3'-diamino-biphenyl, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, m-tolidine, 4,4'-diaminobenzanilide, 3,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)terephthalamide, N,N'-p-phenylenebis(p-aminobenzamide), 4-aminophenyl 4,4'-diaminobenzoate, bis(4-aminophenyl) terephthalate, biphenyl-4,4'-dicarboxylic acid bis(4-aminophenyl) ester, p-phenylene bis(p-aminobenzoate), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylate, [1,1'-biphenyl]-4,4'-diylbis(4-aminobenzoate), 4,4'-oxydianiline, 3,4'-oxydianiline, 3,3'-oxydianiline, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenyl) bis(aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 3,3'-bis(trifluoromethyl)benzidine, 3,3'-bis((aminophenoxy)phenyl)propane, 2,2 '-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(4-(4-aminophenoxy)diphenyl)sulfone, bis(4-(3-aminophenoxy)diphenyl)sulfone, octafluorobenzidine, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,Examples of diamine components that provide repeating units of general formula (II) in which Y1 is a divalent group having an aromatic ring containing a fluorine atom include 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, and 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. Additionally, preferred diamine compounds include 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1"-terphenyl]-4,4"-diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine. The diamine components may be used alone or in combination.

[0093] The divalent group having an alicyclic structure of Y1 is preferably a divalent group having an alicyclic structure with 4 to 40 carbon atoms, and more preferably has at least one 4- to 12-membered aliphatic ring, more preferably a 6-membered aliphatic ring.

[0094] Examples of the divalent group having an alicyclic structure include the following.

[0095] [ka] (In the formula, V1 and V2 each independently represent a direct bond or a divalent organic group, and n 21 ~n 26 each independently represents an integer of 0 to 4, and R 81 ~R 86 are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group, and R 91 , R92 , R 93 are each independently one selected from the group consisting of groups represented by the formula: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-.

[0096] Specific examples of V1 and V2 include a direct bond and a divalent group represented by the above formula (5).

[0097] As the divalent group having an alicyclic structure, the following are particularly preferred because they can provide the resulting polyimide with both high heat resistance and a low coefficient of linear thermal expansion.

[0098] [ka] Among the divalent groups having an alicyclic structure, the following are preferred.

[0099] [ka]

[0100] Examples of diamine components that provide repeating units of general formula (II) in which Y1 is a divalent group having an alicyclic structure include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclobutane ...tert-butylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2- Examples of the diamine component include 4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, diaminobicycloheptane, diaminomethylbicycloheptane, diaminooxybicycloheptane, diaminomethyloxybicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane. The diamine component may be used alone or in combination.

[0101] In addition to the above tetracarboxylic acid component and diamine component, it is also preferable to add a carboxylic acid monoanhydride and carry out the reaction. The carboxylic acid monoanhydride is particularly preferably a dicarboxylic acid monoanhydride, and may be either an aromatic carboxylic acid monoanhydride or an aliphatic carboxylic acid monoanhydride. Aromatic carboxylic acid monoanhydrides are particularly preferable. The aromatic carboxylic acid monoanhydride preferably has an aromatic ring having 6 to 30 carbon atoms, more preferably an aromatic ring having 6 to 15 carbon atoms, and even more preferably an aromatic ring having 6 to 10 carbon atoms.

[0102] Examples of carboxylic acid monoanhydrides include aromatic carboxylic acid monoanhydrides such as phthalic anhydride, 2,3-benzophenonedicarboxylic anhydride, 3,4-benzophenonedicarboxylic anhydride, 1,2-naphthalenedicarboxylic anhydride, 2,3-naphthalenedicarboxylic anhydride, 1,8-naphthalenedicarboxylic anhydride, 1,2-anthracenedicarboxylic anhydride, 2,3-anthracenedicarboxylic anhydride, and 1,9-anthracenedicarboxylic anhydride, and alicyclic carboxylic acid monoanhydrides such as maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, itaconic anhydride, and trimellitic anhydride. Among these, phthalic anhydride is preferred.

[0103] When a carboxylic acid monoanhydride is added, it is more preferable that the following formulae (1) and (2) are satisfied.

[0104] Equation (1) 0.97≦X / Y<1.00 Formula (2) 0.5≦(Z / 2) / (YX)≦1.05 (In the formula, X represents the number of moles of the tetracarboxylic acid component, Y represents the number of moles of the diamine component, and Z represents the number of moles of the carboxylic acid monoanhydride.)

[0105] When X / Y is 0.97 or more, the molecular weight of the polyimide precursor (particularly polyamic acid) is increased, improving the strength and heat resistance of the resulting polyimide film. X / Y is preferably 0.98 or more. When X / Y is less than 1.00, the diamine component is in excess relative to the tetracarboxylic acid component. This allows the formation of amino groups that can be end-capped with carboxylic acid monoanhydride. X / Y is preferably 0.99 or less.

[0106] Furthermore, (Z / 2) / (YX) represents the molar ratio of carboxylic acid monoanhydride to terminally cappable amino groups. By ensuring that X / Y is less than 1.00 and (Z / 2) / (YX) is 0.5 or greater, the terminal capping rate of the polyimide precursor can be increased, resulting in improved CV properties. The closer (Z / 2) / (YX) is to 1, the more preferable it is. (Z / 2) / (YX) is preferably 0.6 or greater, more preferably 0.7 or greater. By ensuring that (Z / 2) / (YX) is 1.05 or less, the amount of free carboxylic acid monoanhydride can be reduced, resulting in improved strength and CV properties of the resulting polyimide film. (Z / 2) / (YX) is preferably 1.03 or less, more preferably 1.01 or less.

[0107] In one embodiment of the present invention, the weight fraction of imide groups (—C(O)NC(O)—) in the polyimide repeating units (i.e., the general formula II) is preferably less than 38.3 wt %, and in a specific embodiment, more preferably 30 wt % or less.

[0108] Here, the polyimide may be a copolymer, i.e., at least one of the tetracarboxylic acid component and the diamine component that give the polyimide may contain two or more compounds. In this case, the weight fraction of the imide group is calculated as a weighted average based on the ratio of the monomers charged. The weight fraction of groups other than the imide group is calculated in the same manner. In the following description, when the weight fraction of a specific group is mentioned, the polyimide includes both a homopolymer and a copolymer.

[0109] In one embodiment of the present invention, the weight fraction of functional groups in the polyimide repeating unit is preferably small. The "functional group in the repeating unit" defined here refers to the portion of the polyimide repeating unit other than the aromatic ring and saturated alkyl chain, such as -O- (ether bond), -CO- (carbonyl group), -COO- (ester), and -SO2-. F and Cl, which substitute hydrogen atoms in the aromatic ring and saturated alkyl chain, are not included in the "functional group in the repeating unit."

[0110] The combined amount of imide groups and "functional groups in the repeating unit" is preferably less than 38.3% by weight, more preferably 30% by weight or less, and even more preferably 25% by weight or less, of the polyimide repeating unit.

[0111] In addition, in one embodiment of the present invention, it is preferable that the content of functional groups other than those mentioned above is low, and it is highly preferable that they are completely absent, regardless of whether they are present in the polyimide repeating unit, at the terminal, or as a separate compound. Such undesirable functional groups include Si-containing groups (siloxane bonds, silyl groups, etc.).

[0112] In a preferred embodiment of the present invention, the tetracarboxylic acid component forming the repeating unit preferably contains a compound selected from tetracarboxylic acid dianhydrides having a fluorene structure in the molecule and tetracarboxylic acid dianhydrides having three or more benzene rings per functional group other than two acid anhydride groups (groups corresponding to the above-mentioned "functional groups in the repeating unit"). Preferred compounds also include compounds that do not have a functional group corresponding to the "functional groups in the repeating unit" other than the two acid anhydride groups, and in this case, the number of benzene rings is preferably two or more, more preferably three or more.

[0113] In a preferred embodiment of the present invention, the diamine component forming the repeating unit preferably contains a compound selected from diamines having a fluorene structure in the molecule and diamines having three or more benzene rings for each functional group other than two amine groups (a group corresponding to the above-mentioned "functional group in the repeating unit"). Note that preferred compounds also include compounds that do not have a functional group corresponding to the "functional group in the repeating unit" other than the two amine groups, and in this case, the number of benzene rings is preferably two or more, more preferably three or more.

[0114] In a preferred embodiment of the present invention, it is preferable that each of the tetracarboxylic acid component and the diamine component forming the repeating unit contains a compound selected from the above-mentioned compounds, i.e., compounds having a fluorene structure in the molecule, and compounds having three or more benzene rings per "functional group in the repeating unit" (including cases where there are no functional groups).

[0115] In one embodiment of the present invention, it is also preferable that the "amount of terminal functional groups" is small. The "amount of terminal functional groups" is calculated based on the charge ratio of the tetracarboxylic acid component and the diamine component when producing the polyimide (when producing the polyamic acid), the purity of each component, the amount of end-capping agent added, and the amount of reactive additive added. The amount of terminal functional groups is calculated from the charge ratio of the tetracarboxylic acid component and the diamine component as follows.

[0116] Since the degree of polymerization of a polyimide obtained with a tetracarboxylic dianhydride / diamine ratio of 1 is theoretically ∞, the terminal group is set to 1 / ∞ = 0. If the tetracarboxylic dianhydride and diamine are not charged in equimolar amounts, for example, if the diamine is in excess, a polyimide with a degree of polymerization n having the structure of formula (II-B) is theoretically produced. n is (Formula) Tetracarboxylic dianhydride / diamine ratio=n / (n+1) The formula weight of the repeating unit is a, and the molecular weight of one terminal diamine is a b Then, the formula weight of polyimide with a degree of polymerization n is (a*n+a b ) so the amount of terminal amine is 2 / (a*n+a b ) [unit: mol / g] In the examples of the present application, the value is expressed in μmol / g.

[0117] [ka]

[0118] In one embodiment of the present invention, the amount of terminal amine groups is preferably 30 μmol / g or less, more preferably 20 μmol / g or less, and even more preferably 10.5 μmol / g or less. In another embodiment of the present invention, the amount of all terminal functional groups is preferably 30 μmol / g or less, more preferably 20 μmol / g or less, and even more preferably 10.5 μmol / g or less.

[0119] In one preferred embodiment of the present invention, the combined weight fraction of imide groups and "functional groups in repeating units" is 30% by weight or less and the "amount of terminal functional groups" is 20 μmol / g or less. In another preferred embodiment, the combined weight fraction of imide groups and "functional groups in repeating units" is 40% by weight or less and the "amount of terminal functional groups" is 10.5 μmol / g or less. It is also highly preferred that the combined weight fraction of imide groups and "functional groups in repeating units" is 30% by weight or less and the "amount of terminal functional groups" is 10.5 μmol / g or less.

[0120] Controlling the functional groups in the polyimide (imide groups, functional groups in the repeating units, and terminal functional groups) as described above is an element that should be considered in order to obtain a polyimide having the CV characteristics of the present invention.

[0121] <<New polyimide precursors and polyimides>> The present application also discloses polyimide precursors and polyimides containing novel structures. The novel polyimide precursors and polyimides include a tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA); (B-1) at least one diamine selected from 1,4-diaminobenzene, [1,1':4',1"-terphenyl]-4,4"-diamine, and 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, and (B-2) At least one diamine selected from 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine That is, in the general formula I and general formula II, X1 is derived from the tetracarboxylic acid component (A) and Y1 is derived from the diamine component (B).

[0122] The tetracarboxylic acid component (A) preferably contains 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) at a ratio of 40 mol% or more. Furthermore, it is also preferable that the tetracarboxylic acid component (A) contains, in addition to s-BPDA, (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate). In addition to these, the tetracarboxylic acid component (A) may contain the tetracarboxylic acid dianhydrides listed above. For example, it may contain a compound selected from tetracarboxylic acid dianhydrides having a fluorene structure in the molecule and tetracarboxylic acid dianhydrides having three or more benzene rings per functional group other than two acid anhydride groups (groups corresponding to the "functional groups in the repeating unit"). The amount of tetracarboxylic dianhydrides other than s-BPDA and (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) is preferably 30 mol % or less, more preferably 20 mol % or less, and may be 0 mol %.

[0123] The diamine component (B) preferably contains the diamine (B-1) and the diamine (B-2) in a total amount of 40 mol % or more. The diamine component (B) may contain the diamine compounds listed above in addition to the diamine (B-1) and the diamine (B-2). For example, the diamine component (B) may contain a compound selected from diamines having a fluorene structure in the molecule and diamines having three or more benzene rings per functional group other than two amine groups (groups corresponding to the "functional group in the repeating unit"). A preferred example of the compound is 1,1':4',1":4",1"'-quaterphenyl-4,4"'-diamine. The amount of the diamine compounds other than the diamine (B-1) and the diamine (B-2) is preferably 30 mol % or less, more preferably 20 mol % or less, and may even be 0 mol %.

[0124] In addition, among the repeating units of the polyimide precursor or polyimide, the total proportion of repeating units derived from s-BPDA and diamine (B-1) and repeating units derived from s-BPDA and diamine (B-2) is preferably 40 mol % or more.

[0125] This novel polyimide has excellent CV properties, and it is preferable to select the concomitant compounds, the tetracarboxylic dianhydride / diamine ratio to be charged, and the like so that at least one, preferably two, and more preferably three of the weight fraction of imide groups in the polyimide repeating unit, the combined weight fraction of imide groups and "functional groups in the repeating unit," and the "amount of terminal functional groups" fall within the above-mentioned ranges (particularly preferred ranges).

[0126] <<Polyimide film manufacturing method>> The production of polyimide, particularly the production of a polyimide film via a laminate in which a polyimide film is formed on a carrier substrate, will be described below.

[0127] An example of a method for producing a polyimide film is outlined below. (1) A method of forming a polyimide film by casting a polyimide precursor (particularly a polyamic acid) solution or a polyimide precursor solution composition prepared by adding an imidization catalyst, a dehydrating agent, inorganic fine particles, etc. to a polyimide precursor solution as needed onto a carrier substrate and heating the solution to dehydrate, cyclize, and remove the solvent (thermal imidization); (2) A method in which a cyclization catalyst and a dehydrating agent are added to a polyimide precursor (particularly a polyamic acid) solution, and further inorganic fine particles or the like are optionally added to form a polyimide precursor solution composition, which is cast on a carrier substrate and chemically dehydrated and cyclized, and then heated to remove the solvent and imidize, thereby forming a polyimide film (chemical imidization); (3) When the polyimide is soluble in an organic solvent, a polyimide solution composition containing optional additives such as inorganic fine particles is cast onto a carrier substrate, and the polyimide film is formed by heating the composition to a predetermined temperature while removing the solvent. Examples include:

[0128] <Polyimide precursor solution, polyimide solution> First, we will explain how to prepare a polyimide precursor solution and a polyimide solution. A polyimide precursor solution or a polyimide solution can be obtained by polymerizing approximately equimolar amounts of a tetracarboxylic acid component and a diamine component in an organic solvent. Alternatively, two or more polyimide precursors, each containing an excess of one of the components, can be synthesized in advance, and the polyimide precursor solutions can be combined and mixed under reaction conditions.

[0129] The organic solvent is not particularly limited, but examples thereof include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and N-vinyl-2-pyrrolidone; cyclic ester solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, and α-methyl-γ-butyrolactone; carbonate solvents such as ethylene carbonate and propylene carbonate; glycol-based solvents such as triethylene glycol; phenol-based solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol; acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, and dimethyl sulfoxide. In addition, other common organic solvents, for example, alcoholic solvents such as methanol and ethanol, phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl Other examples of organic solvents that can be used include ethyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, N-methylcaprolactam, hexamethylphosphorotriamide, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether, 1,4-dioxane, dimethyl sulfoxide, dimethyl sulfone, diphenyl ether, diphenyl sulfone, tetramethylurea, anisole, turpentine, mineral spirits, petroleum naphtha-based solvents, biodegradable methyl lactate, ethyl lactate, and butyl lactate. One or more organic solvents may be used.

[0130] When carrying out the polymerization reaction to obtain a polyimide precursor solution and a polyimide solution, respectively, the concentration of all monomers in the organic solvent (substantially equal to the solids concentration of the polyimide precursor solution or polyimide solution) may be appropriately selected depending on the intended use and production purpose. The solids concentration of the resulting polyimide precursor solution or polyimide solution is not particularly limited, but is preferably 5% to 45% by mass, more preferably 7% to 40% by mass, and even more preferably 9% to 30% by mass, based on the total amount of the polyimide precursor or polyimide and the solvent. A solids concentration lower than 5% by mass may result in poor productivity and poor handling during use, while a solids concentration higher than 45% by mass may result in a loss of fluidity of the solution.

[0131] The solution viscosity of the polyimide precursor solution or polyimide solution at 30°C is not particularly limited, but is preferably 1000 Pa·s or less, more preferably 0.1 to 500 Pa·s, even more preferably 0.1 to 300 Pa·s, and particularly preferably 0.1 to 200 Pa·s for ease of handling. If the solution viscosity exceeds 1000 Pa·s, the solution will lose fluidity, making it difficult to apply the solution evenly to a carrier substrate such as metal or glass. If the solution viscosity is lower than 0.1 Pa·s, dripping or repelling may occur during application to a carrier substrate such as metal or glass, making it difficult to obtain a polyimide film with high performance.

[0132] As an example of a method for producing a polyimide precursor solution, the polymerization reaction of the tetracarboxylic acid component and the diamine component is carried out by, for example, mixing the components in substantially equimolar amounts or by adding a slight excess of either the acid component or the diamine component, and reacting the components at a reaction temperature of 100°C or lower, preferably 80°C or lower, for about 0.2 to 60 hours to obtain a polyimide precursor solution.

[0133] As an example of a production example of a polyimide solution, the polymerization reaction of the tetracarboxylic acid component and the diamine component can be carried out by, for example, mixing them in substantially equimolar amounts or with a slight excess of either component (acid component or diamine component) and then performing the reaction by a known method, for example, at a reaction temperature of 140°C or higher, preferably 160°C or higher (preferably 250°C or lower, and further preferably 230°C or lower) for about 1 to 60 hours to obtain a polyimide solution.

[0134] Furthermore, when a carboxylic acid monoanhydride (particularly a dicarboxylic acid monoanhydride) is added as described above, a method including a first step of reacting a tetracarboxylic acid component with a diamine component in a solvent, preferably in a molar ratio that satisfies the above-described formula (1), to obtain a polyimide precursor (particularly a polyamic acid) having amino groups at its terminals, and a second step of adding a carboxylic acid monoanhydride, preferably in a molar ratio that satisfies the above-described formula (2), to react the components and cap the terminals of the polyimide precursor (particularly a polyamic acid).

[0135] In the first step, the reaction is carried out at a relatively low temperature, for example, 100°C or below, preferably 80°C or below, to suppress the imidization reaction. While not limited thereto, the reaction temperature is typically 25°C to 100°C, preferably 40°C to 80°C, and more preferably 50°C to 80°C, and the reaction time is typically about 0.1 to 24 hours, preferably about 2 to 12 hours. By keeping the reaction temperature and reaction time within the above ranges, a solution composition of a high-molecular-weight polyimide precursor can be efficiently obtained. The reaction can be carried out in an air atmosphere, but is typically carried out in an inert gas atmosphere, preferably a nitrogen gas atmosphere.

[0136] In the second step, the reaction temperature may be set appropriately, but from the viewpoint of reliably capping the ends of the polyimide precursor, it is preferably 25° C. to 70° C., more preferably 25° C. to 60° C., and even more preferably 25° C. to 50° C. The reaction time is usually about 0.1 to 24 hours.

[0137] The polyimide precursor solution or polyimide solution thus obtained can be used for producing a polyimide film as it is, or after removing the organic solvent, if necessary, or after adding a new organic solvent.

[0138] If thermal imidization is to be performed, an imidization catalyst, an organic phosphorus-containing compound, inorganic fine particles, etc. may be added to the polyimide precursor solution as needed. If chemical imidization is to be performed, a cyclization catalyst, a dehydrating agent, inorganic fine particles, etc. may be added to the polyimide precursor solution as needed. If necessary, inorganic fine particles, etc. may be added to the polyimide solution.

[0139] Examples of the imidization catalyst include substituted or unsubstituted nitrogen-containing heterocyclic compounds, N-oxide compounds of the nitrogen-containing heterocyclic compounds, substituted or unsubstituted amino acid compounds, and aromatic hydrocarbon compounds or aromatic heterocyclic compounds having a hydroxyl group. In particular, lower alkylimidazoles such as 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, and 5-methylbenzimidazole, benzimidazoles such as N-benzyl-2-methylimidazole, phenylimidazoles such as 2-phenylimidazole, isoquinoline, and substituted pyridines such as 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, and 4-n-propylpyridine can be preferably used. The amount of the imidization catalyst used is preferably about 0.01 to 2 equivalents, particularly about 0.02 to 1 equivalent, relative to the amide acid units of the polyamic acid. Use of the imidization catalyst may improve the physical properties of the resulting polyimide film, particularly the elongation and edge tear resistance.

[0140] Examples of organic phosphorus-containing compounds include phosphate esters such as monocaproyl phosphate, monooctyl phosphate, monolauryl phosphate, monomyristyl phosphate, monocetyl phosphate, monostearyl phosphate, triethylene glycol monotridecyl ether phosphate monoester, tetraethylene glycol monolauryl ether phosphate monoester, diethylene glycol monostearyl ether phosphate monoester, dicaproyl phosphate, dioctyl phosphate, dicapryl phosphate, dilauryl phosphate, dimyristyl phosphate, dicetyl phosphate, distearyl phosphate, tetraethylene glycol mononeopentyl ether phosphate diester, triethylene glycol monotridecyl ether phosphate diester, tetraethylene glycol monolauryl ether phosphate diester, diethylene glycol monostearyl ether phosphate diester, trimethyl phosphate, and triphenyl phosphate triester, as well as amine salts of these phosphate esters. Examples of the amine include ammonia, monomethylamine, monoethylamine, monopropylamine, monobutylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, monoethanolamine, diethanolamine, and triethanolamine.

[0141] Examples of the cyclization catalyst include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as isoquinoline, pyridine, α-picoline, and β-picoline.

[0142] Examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride.

[0143] Examples of inorganic fine particles include inorganic oxide powders such as fine titanium dioxide powder, silicon dioxide (silica) powder, magnesium oxide powder, aluminum oxide (alumina) powder, and zinc oxide powder; inorganic nitride powders such as fine silicon nitride powder and titanium nitride powder; inorganic carbide powders such as silicon carbide powder; and inorganic salt powders such as fine calcium carbonate powder, calcium sulfate powder, and barium sulfate powder. Two or more of these inorganic fine particles may be used in combination. Known methods can be used to uniformly disperse these inorganic fine particles.

[0144] In one embodiment, the polyimide precursor solution or polyimide solution preferably does not contain a silane coupling agent such as an alkoxysilane. In polyimide films using a silane coupling agent, the silane coupling agent may bleed out. This can lead to problems such as a decrease in the CV characteristics of the polyimide film, a decrease in adhesive strength, and swelling of the laminate. Furthermore, adding or reacting a silane coupling agent to a polyimide precursor solution can also cause the problem of a decrease in the viscosity stability of the polyimide precursor solution. To avoid such problems, it is preferable not to use a silane coupling agent.

[0145] <Production of Laminates and Electronic Devices> In the manufacture of electronic devices, a polyimide precursor solution or polyimide solution (including a composition solution containing additives, if necessary) is first cast onto a carrier substrate, followed by heat treatment to imidize and remove solvent (mainly remove solvent in the case of a polyimide solution), thereby forming a polyimide film and obtaining a laminate of the carrier substrate and polyimide film. While there are no particular limitations on the carrier substrate, glass substrates such as soda-lime glass, borosilicate glass, and alkali-free glass, or metal substrates such as iron, stainless steel, and copper, are commonly used. The method for casting the polyimide precursor solution or polyimide solution onto the carrier substrate is not particularly limited, but examples include conventional methods such as spin coating, screen printing, bar coating, and electrodeposition. When using a polyimide precursor solution, the heat treatment conditions are not particularly limited, but include drying at a temperature range of 50°C to 150°C, followed by treatment at a maximum heating temperature of, for example, 150°C to 600°C, preferably 200°C to 550°C, and more preferably 250°C to 500°C. The heat treatment conditions when using a polyimide solution are not particularly limited, but the maximum heating temperature is, for example, 100°C to 600°C, preferably 150°C or higher, more preferably 200°C or higher, and preferably 500°C or lower, more preferably 450°C or lower.

[0146] The thickness of the polyimide film is preferably 1 μm or more. If the thickness is less than 1 μm, the polyimide film will not maintain sufficient mechanical strength, and may be unable to withstand stress and break when used, for example, as a flexible device substrate. The thickness of the polyimide film is also preferably 20 μm or less. If the thickness of the polyimide film exceeds 20 μm, it may become difficult to thin the flexible device. To further thin the polyimide film while maintaining sufficient durability for a flexible device, the thickness of the polyimide film is more preferably 2 to 10 μm.

[0147] The resulting polyimide film is firmly laminated to a carrier substrate such as a glass substrate, etc. The peel strength between the carrier substrate such as a glass substrate and the polyimide film, as measured in accordance with JIS K6854-1, is generally 50 mN / mm or more, preferably 100 mN / mm or more, more preferably 200 mN / mm or more, and even more preferably 300 mN / mm or more.

[0148] A second layer such as a resin film or an inorganic film may be laminated on the resulting polyimide film to form a flexible device substrate. In particular, an inorganic film is suitable as a water vapor barrier layer. Examples of water vapor barrier layers include silicon nitride (SiN x ), silicon oxide (SiO x ), silicon oxynitride (SiO x N y Examples of suitable inorganic films include inorganic films containing inorganic substances selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides, such as aluminum oxide (Al2O3), titanium oxide (TiO2), and zirconium oxide (ZrO2). Generally, methods for forming these thin films include physical vapor deposition (CVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD). This second layer can also be a multi-layer structure. Even in devices having a second layer on a polyimide film, the polyimide film may affect the semiconductor layer through the second layer. Therefore, the polyimide of the present invention, which has good CV characteristics, is preferably used to improve device characteristics and durability.

[0149] A flexible device substrate may be formed by laminating a polyimide film on a resin film or an inorganic film. The polyimide film can be laminated on the resin film or the inorganic film using a polyimide precursor solution or a polyimide solution in the same manner as in the case of the carrier substrate.

[0150] The polyimide film obtained by the present invention can be firmly laminated to an inorganic film as a substrate. The peel strength between the polyimide film and the inorganic film (e.g., a silicon oxide film) measured in accordance with JIS K6854-1 is generally 20 mN / mm or more, preferably 30 mN / mm or more, more preferably 40 mN / mm or more, and even more preferably 50 mN / mm or more.

[0151] In the manufacture of electronic devices, elements and circuits necessary for the device are formed on the formed laminate (particularly the polyimide film). The elements and circuits formed and the manufacturing process vary depending on the type of device. When manufacturing a TFT liquid crystal display device, an amorphous silicon TFT, for example, is formed on the polyimide film. The TFT includes, for example, a gate metal layer, a semiconductor layer such as an amorphous silicon film, a silicon nitride gate dielectric layer, and an ITO pixel electrode. Further structures necessary for the liquid crystal display can be formed on top of this by known methods. Since the polyimide film obtained in the present invention has excellent properties such as heat resistance and toughness, the method for forming circuits, etc. is not particularly limited.

[0152] When a flexible device is intended as the electronic device, a device substrate (particularly a polyimide film) having a circuit or the like formed on its surface is peeled off from a carrier substrate. The peeling method is not particularly limited, and can be performed by, for example, laser peeling, in which a laser or the like is irradiated from the carrier substrate side to peel off, or mechanical peeling, in which the substrate is mechanically peeled off.

[0153] The polyimides and polyimide films of the present invention (including those having a second layer such as a resin film or an inorganic film laminated thereon) are particularly suitable as substrates for electronic devices that require thinning and flexibility. The term "flexible (electronic) device" as used herein means that the device itself is flexible, and the device is typically completed by forming a semiconductor layer (such as a transistor or diode as an element) on a substrate. It does not refer to, for example, COF (chip-on-film) devices in which "rigid" semiconductor elements such as IC chips are mounted on a conventional FPC (flexible printed wiring board). Flexible (electronic) devices suitable for use with the polyimides and polyimide films of the present invention described above and below include display devices such as liquid crystal displays, organic electroluminescence (EL) displays, and electronic paper, as well as light-receiving devices such as solar cells and CMOS.

[0154] The polyimide of the present invention can be used in a variety of applications. However, in order to obtain the effect of excellent CV characteristics, it is preferably used in a device in which the polyimide is in direct contact with a semiconductor or in a device in which the polyimide is laminated via a thin film (e.g., a thin film of 200 nm or less, preferably 100 nm or less, such as the above-mentioned second layer).

[0155] In addition, in the above explanation, a method of forming elements and circuits on a laminate of a polyimide film and a carrier substrate was described, but elements and circuits may also be formed on a single polyimide film as long as there is no problem in forming the elements and circuits.

[0156] The semiconductors include silicon such as single crystal silicon, amorphous silicon, and polysilicon (which may be doped with p-type or n-type impurities), as well as gallium nitride and other compound semiconductors. [Example]

[0157] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[0158] The measurement methods of the characteristics used in the following examples are shown below.

[0159] <Measurement Method of C-V Characteristics> The C-V characteristics were measured under the following conditions using the system shown in the schematic diagram of Fig. 1. Measuring device: Mercury probe type CV measuring device manufactured by Horiba Jobin Yvon (Mercury probe Model 802-150 (Materials Development Corporation)) Mercury electrode area: 0.00475 cm 2 DC voltage scanning conditions: After holding at +40 V for 30 s, a negative scan is performed from +40 V to -40 V, held at -40 V for 30 s, and then a positive scan is performed to +40 V. This was repeated 3 cycles. The scanning speed of the DC voltage was 0.25 V / sec in Examples 1 to 7 and Comparative Examples 1 to 3, and 0.18 V / sec in Examples 8 to 16 and Comparative Examples 4 to 10. The reason for setting it to 0.18 V / sec in the latter half of the examples and comparative examples is to reduce measurement noise, but there is no difference in the measurement data obtained with 0.25 V / sec and the value of the maximum gradient (see Example 16 and Comparative Example 10). AC voltage conditions: AC sine wave with a frequency of approximately 2.5 kHz and an amplitude of 0.1 V Measurement temperature: Room temperature

[0160] <Method for Obtaining Gradient> As an approximation of the derivative function of the normalized C-V curve, at a certain voltage V n1 the normalized capacitance C n1 at that time, and V n1 V which is V + 1.5 [V] n2 the normalized capacitance C n2 at that time, from the absolute value "|(C n2 - C n1 ) / (V n2 - V n1 )|", this value was calculated for the entire normalized C-V curve, and the maximum value of |(C n2 - C n1 ) / (V n2 - V n1 )|" was adopted as the gradient of the composition.

[0161] The monomers and additives used in the examples and comparative examples are shown below.

[0162] Monomer A: 3,3',4,4'-biphenyltetracarboxylic dianhydride (formula weight 294.22), purity (%) 99.9 Monomer A2: 3,3',4,4'-biphenyltetracarboxylic dianhydride (formula weight 294.22), purity (%) 99.0 (low purity) Monomer B: (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (formula weight: 726.66), purity (%): 98.2 Monomer C: 1,4-diaminobenzene (formula weight 108.14), purity (%) 100.0 Monomer D: 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine (formula weight 684.78), purity (%) 99.0 Monomer E: [1,1':4',1"-terphenyl]-4,4"-diamine (formula weight 260.31), purity (%) 99.1 Monomer F: 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine (formula weight 468.51), purity (%) 99.1 Monomer G: 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (formula weight 344.48), purity (%) 99.7 Monomer H: 9,9-bis(4-aminophenyl)fluorene (formula weight 348.43), purity (%) 99.2 Monomer I: Phthalic anhydride (formula weight 148.11), purity (%) 100.0 Additive: 3-aminopropyltriethoxysilane (formula weight 218.32), purity (%) 99.7 Monomer J: 5-(phenylethynyl)isobenzofuran-1,3-dione (formula weight 248.22), purity: 98.4% Monomer K: 5-(3-oxo-3-phenylprop-1-yn-1-yl)isobenzofuran-1,3-dione (formula weight 276.23), purity: 99.8% Monomer L: 5,5'-(ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione) (formula weight 318.23), purity: 99.0% Monomer M: 5,5'-(perfluoropropane-2,2-diyl)bis(isobenzofuran-1,3-dione) (formula weight 444.24), purity: 99.1% Monomer N: 5,5'-oxybis(isobenzofuran-1,3-dione) (formula weight 310.21), purity: 99.73% Monomer O: Octahydro-3H,3"H-dispiro[[4,7]methanoisobenzofuran]-1,1",3,3",4'(4H,4"H)-pentaone (CpODA) (formula weight 384.37), purity: 99.3% Monomer P: cyclohexane-1,4-diamine (formula weight 114.19), purity: 99.98% Monomer Q: 4,4'-oxydianiline (formula weight 200.24), purity: 99.98% Monomer R: 1H,3H-benzo[1,2-c:4,5-c:4,5c']difuran-1,3,5,7-tetraone (formula weight 218.12), purity: 99.73%

[0163] The chemical structure of the monomer is shown below.

[0164] [ka]

[0165] [ka]

[0166] [ka]

[0167] [ka]

[0168] [ka]

[0169] [ka]

[0170] [Reference Example 1] (Composition of Example 1) (Monomer A 50 / Monomer B 50 / / Monomer C 50 / Monomer D 50) A reaction vessel purged with nitrogen gas was charged with 1,4-diaminobenzene (50 mol%), 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine (50 mol%), and NMP. The mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. Subsequently, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (50 mol%) and (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (50 mol%) were added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 1.82 Pa·s (25°C).

[0171] [Reference Example 2] (Composition of Example 2) (Monomer A 50 / Monomer B 50 / / Monomer D 50 / Monomer E 50) A reaction vessel purged with nitrogen gas was charged with [1,1':4',1"-terphenyl]-4,4"-diamine (50 mol%) (50 mol%), 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine (50 mol%), and NMP. The mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. Subsequently, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (50 mol%) and (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (50 mol%) were added and the mixture was stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 0.742 Pa·s (25°C).

[0172] [Reference Example 3] (Composition of Example 3) (Monomer A 50 / Monomer B 50 / / Monomer E 50 / Monomer F 50) A reaction vessel purged with nitrogen gas was charged with [1,1':4',1"-terphenyl]-4,4"-diamine (50 mol%), 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine (50 mol%), and NMP. The mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. Subsequently, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (50 mol%) and (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (50 mol%) were added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 0.886 Pa·s (25°C).

[0173] [Reference Example 4] (Composition of Example 4) (Monomer A 100 / / Monomer G 50 / Monomer H 50) A reaction vessel purged with nitrogen gas was charged with 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (50 mol%), 9,9-bis(4-aminophenyl)fluorene (50 mol%), and NMP. The mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. 3,3',4,4'-tetracarboxylic acid biphenyl dianhydride (100 mol%) was then added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 3.249 Pa·s (25°C).

[0174] [Reference Example 5] (Composition of Example 5) (Monomer A 100 / / Monomer G 50 / Monomer H 50) A reaction vessel purged with nitrogen gas was charged with 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (50 mol%), 9,9-bis(4-aminophenyl)fluorene (50 mol%), and NMP. The mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. 3,3',4,4'-tetracarboxylic acid biphenyl dianhydride (100 mol%) was then added and stirred for an additional 30 minutes to obtain a polyamic acid solution. The mixture was then heated to 190°C and held for 3 hours to allow imidization, yielding a liquid polyimide resin composition (polyimide solution) with a viscosity of 4.03 Pa·s (25°C).

[0175] [Reference Example 6] (Composition of Example 6) (Monomer A 100 / / Monomer C 100) 1,4-Diaminobenzene (100 mol%) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomer. 3,3',4,4'-Tetracarboxylic acid biphenyl dianhydride (100 mol%) was then added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 6.6 Pa·s (25°C).

[0176] [Reference Example 7] (Composition of Example 7) (Monomer A 98 / / Monomer C 100 / / Monomer I 4) A reaction vessel purged with nitrogen gas was charged with 1,4-diaminobenzene (100 mol%) and NMP, and the mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (98 mol%) was added and stirred for an additional 30 minutes. Then, phthalic anhydride (4 mol%) was added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 3.11 Pa·s (25°C).

[0177] [Reference Example 8] (Composition of Comparative Example 1) (Monomer A 99.5 / / Monomer C 100 / / Additive) A reaction vessel purged with nitrogen gas was charged with 1,4-diaminobenzene (100 mol%) and NMP, and the mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomers. 3,3',4,4'-tetracarboxylic biphenyl dianhydride (99.5 mol%) and 3-aminopropyltriethoxysilane (0.05 parts based on the total amount of monomers) were then added, and the mixture was stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 28.75 Pa·s (25°C).

[0178] [Reference Example 9] (Composition of Comparative Example 2) (Monomer A 98 / / Monomer C 100) 1,4-Diaminobenzene (100 mol%) and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomer. 3,3',4,4'-Tetracarboxylic acid biphenyl dianhydride (98 mol%) was then added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 3.11 Pa s (25°C).

[0179] [Reference Example 10] (Composition of Comparative Example 3) (Monomer A2 100 / / Monomer C 100) A reaction vessel purged with nitrogen gas was charged with 1,4-diaminobenzene (100 mol%) and NMP, and the mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomer. 3,3',4,4'-Tetracarboxylic acid biphenyl dianhydride (monomer A2; low purity) (100 mol%) was then added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 480 Pa·s (25°C).

[0180] <Examples 1 to 3> A solution obtained by further diluting the polyamic acid solutions produced in Reference Examples 1 to 3 was spin-coated onto a 6-inch silicon wafer (625 μm thick, resistivity 4 Ωcm, p-type (impurity boron)), and the wafer was heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and at 330°C for 5 minutes to form a polyimide film with a thickness of 0.75 μm. CV measurement was performed on the obtained polyimide film, and the composition of the Reference Examples used is shown in Table 1.

[0181] Example 4 As in Example 1, a further diluted solution of the polyamic acid solution produced in Reference Example 4 was spin-coated onto a 6-inch silicon wafer, and the wafer was heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and then at 360°C for 5 minutes to form a polyimide film with a thickness of 0.75 μm. The results are shown in Table 1.

[0182] <Example 5> As in Example 1, a solution obtained by further diluting the polyimide solution produced in Reference Example 5 was spin-coated onto a 6-inch silicon wafer, and the wafer was heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and then at 300°C for 5 minutes to form a polyimide film with a thickness of 0.75 μm. The results are shown in Table 1.

[0183] <Examples 6 and 7, Comparative Examples 1, 2, and 3> As in Example 1, a 6-inch silicon wafer was spin-coated with a further diluted solution of the polyamic acid solution produced in Reference Examples 6, 7, 8, 9, and 10, and the wafer was heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and then at 450°C for 5 minutes to form a polyimide film with a thickness of 0.75 μm. The results are shown in Table 1.

[0184] [Table 1]

[0185] In the following Reference Examples 11 to 26, similarly to Reference Example 1 above, a diamine compound and NMP were charged into a reaction vessel purged with nitrogen gas, and the mixture was heated and stirred at 40°C for 15 minutes to dissolve the monomer. Tetracarboxylic dianhydride was then added and stirred for 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution). However, in the cases where a terminal blocking agent was added (Reference Examples 16 to 18), the terminal blocking agent was then added and stirred for an additional 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution), similarly to Reference Example 7.

[0186] [Reference Example 11] (Composition of Example 8) (Monomer A 70 / Monomer M 30 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (70 mol%) + 5,5'-(perfluoropropane-2,2-diyl)bis(isobenzofuran-1,3-dione) (monomer M) (30 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 1.160 Pa·s (25°C)

[0187] [Reference Example 12] (Composition of Example 9) (Monomer A 70 / Monomer N 30 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (70 mol%) + 5,5'-oxybis(isobenzofuran-1,3-dione) (monomer N) (30 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 1.250 Pa·s (25°C)

[0188] [Reference Example 13] (Composition of Example 10) (Monomer A 70 / Monomer O 30 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (70 mol%) + CpODA (monomer O) (30 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 1.303 Pa·s (25°C)

[0189] [Reference Example 14] (Composition of Example 11) (Monomer A 100 / / Monomer C 70 / Monomer P 30) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (100 mol%) Diamine component: 1,4-diaminobenzene (70 mol%) + cyclohexane-1,4-diamine (monomer P) (30 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 1.811 Pa·s (25°C)

[0190] [Reference Example 15] (Composition of Example 12) (Monomer A 100 / / Monomer C 70 / Monomer Q 30) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (100 mol%) Diamine component: 1,4-diaminobenzene (70 mol%) + 4,4'-oxydianiline (monomer Q) (30 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 1.562 Pa·s (25°C)

[0191] [Reference Example 16] (Composition of Example 13) (Monomer A 98 / / Monomer C 100 / / Monomer J 4) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (98 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) End-capping agent: 5-(phenylethynyl)isobenzofuran-1,3-dione (monomer J) (4 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 3.11 Pa·s (25°C)

[0192] [Reference Example 17] (Composition of Example 14) (Monomer A 98 / / Monomer C 100 / / Monomer K 4) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (98 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) End-capping agent: 5-(3-oxo-3-phenylprop-1-yn-1-yl)isobenzofuran-1,3-dione (monomer K) (4 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 3.11 Pa·s (25°C)

[0193] [Reference Example 18] (Composition of Example 15) (Monomer A 98 / / Monomer C 100 / / Monomer L 2) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (98 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) End-capping agent: 5,5'-(ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione) (monomer L) (2 mol%) (Note: Monomer L is a tetracarboxylic dianhydride, but like the end-capping agent, it was added last.) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 3.11 Pa·s (25°C)

[0194] [Reference Example 19] (Composition of Comparative Example 4) (Monomer A 30 / Monomer R 70 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (30 mol%) + 1H,3H-benzo[1,2-c:4,5-c:4,5c']difuran-1,3,5,7-tetraone (monomer R) (70 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 1.23 Pa·s (25°C)

[0195] [Reference Example 20] (Composition of Comparative Example 5) (Monomer A 68.6 / Monomer M 29.4 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (68.6 mol%) + 5,5'-(perfluoropropane-2,2-diyl)bis(isobenzofuran-1,3-dione) (monomer M) (29.4 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 0.130 Pa·s (25°C)

[0196] [Reference Example 21] (Composition of Comparative Example 6) (Monomer A 68.6 / Monomer N 29.4 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (68.6 mol%) + 5,5'-oxybis(isobenzofuran-1,3-dione) (monomer N) (29.4 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 0.144 Pa·s (25°C)

[0197] [Reference Example 22] (Composition of Comparative Example 7) (Monomer A 68.6 / Monomer O 29.4 / / Monomer C 100) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (68.6 mol%) + CpODA (monomer O) (29.4 mol%) Diamine component: 1,4-diaminobenzene (100 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 0.102 Pa·s (25°C)

[0198] [Reference Example 23] (Composition of Comparative Example 8) (Monomer A 98 / / Monomer C 70 / Monomer P 30) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (98 mol%) Diamine component: 1,4-diaminobenzene (70 mol%) + cyclohexane-1,4-diamine (monomer P) (30 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 0.281 Pa·s (25°C)

[0199] [Reference Example 24] (Composition of Comparative Example 9) (Monomer A 98 / / Monomer C 70 / Monomer Q 30) Tetracarboxylic dianhydride: 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A) (98 mol%) Diamine component: 1,4-diaminobenzene (70 mol%) + 4,4'-oxydianiline (monomer Q) (30 mol%) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 0.062 Pa·s (25°C)

[0200] <Examples 8 to 15 and Comparative Examples 5 to 9> Using the polyamic acid solutions produced in Reference Examples 11 to 18 and Reference Examples 20 to 24, a 0.75 μm thick polyimide film was formed under the same conditions as in Example 4, i.e., a solution obtained by further diluting the polyamic acid solution was spin-coated onto a 6-inch silicon wafer, and the wafer was heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and at 360°C for 5 minutes. The results are shown in Table 2.

[0201] <Comparative Example 4> The polyamic acid solution prepared in Reference Example 19 was used under the same conditions as in Example 6, i.e., a further diluted solution of the polyamic acid solution was spin-coated onto a 6-inch silicon wafer, and the wafer was heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and then at 450°C for 5 minutes, to form a polyimide film with a thickness of 0.75 μm. The results are shown in Table 2.

[0202] <Example 16, Comparative Example 10> In Example 16 and Comparative Example 10, the same samples as in Example 6 and Comparative Example 1 were prepared, respectively, to confirm the effect of the DC voltage scanning rate when measuring the CV characteristics. The maximum gradients of Example 16 and Comparative Example 10, in which the DC voltage scanning rate when measuring the CV characteristics was changed to 0.18 V / sec, were 0.007 / V and 0.004 / V, respectively, which were consistent with the results of Example 6 and Comparative Example 1, measured at a scanning rate of 0.25 V / sec.

[0203] [Table 2] [Industrial Applicability]

[0204] The polyimide of the present invention is suitable for use in electronic devices, such as substrates for flexible devices.

[0205] 1 silicon wafer 2 Polyimide film 3 Mercury electrode 4 DC power supply 5 AC power supply

Claims

1. a tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, in which the amount of tetracarboxylic acid dianhydrides other than 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) is 30 mol % or less of the total tetracarboxylic acid dianhydrides; (B-1) at least one diamine selected from 1,4-diaminobenzene, [1,1':4',1"-terphenyl]-4,4"-diamine, and 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, and (B-2) At least one diamine selected from 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine and a diamine component (B) containing (However, when diamine component (B) contains 1,4-diaminobenzene and 9,9-bis(4-aminophenyl)fluorene, the amount of diamine compounds other than diamine (B-1) and diamine (B-2) is 20 mol % or less, and diamine component (B) does not contain a siloxane-based diamine represented by the following formula (2) in the range of 2 to 40 mol %. 【Chemical 1】 (n is in the range of 1 to 30. R １７ and R １８ may be the same or different and represent an alkylene group or a phenylene group having 1 to 30 carbon atoms. １９ ~R ２２ may be the same or different and represent an alkyl group having 1 to 30 carbon atoms, a phenyl group, or a phenoxy group.

2. 2. The polyimide precursor according to claim 1, wherein the diamine component (B) contains the diamine (B-1) and the diamine (B-2) in a total amount of 40 mol % or more.

3. 2. The polyimide precursor according to claim 1, wherein the sum of the proportions of the repeating units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and the diamine (B-1) and the repeating units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and the diamine (B-2) is 40 mol % or more.

4. A polyimide obtained by imidizing the polyimide precursor according to any one of claims 1 to 3.

5. A polyimide film in the form of a film of the polyimide according to claim 4.

6. A flexible electronic device comprising the polyimide film of claim 5.

7. 7. A method for manufacturing a flexible electronic device according to claim 6, comprising the steps of: A method for producing a laminate comprising the steps of applying a polyimide precursor solution or a polyimide precursor solution composition containing the polyimide precursor according to any one of claims 1 to 3 onto a carrier substrate and imidizing the polyimide precursor solution or the polyimide precursor solution composition to form a laminate having the carrier substrate and a polyimide film. A manufacturing method characterized by:

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