Polyimide, laminate and electronic device containing those

Abstract

To provide a flexible electronic device containing a polyimide film showing excellent C-V characteristics.SOLUTION: A film formed of a polyimide shows, when measuring the capacitance-voltage of a laminate in which a polyimide film was formed with a film thickness of 0.75 μm on a silicon wafer with a resistance value of 4 Ωcm, a maximum slope of 0.005 / V or more. (However, the maximum gradient is determined by measuring the capacitance while scanning in a positive direction and scanning in a negative direction with a DC voltage applied to the polyimide film relative to the silicon wafer between the lowest voltage V1 and the highest voltage V2. It means the maximum absolute value of the slope in the normalized capacitance-voltage curve during the third forward scan, and the normalized capacitance-voltage curve is normalized with the capacitance at the lowest voltage V1 as 1. ).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a polyimide suitably used for electronic device applications such as a substrate of a flexible device, and further relates to a polyimide film, a laminate including the polyimide film, and an electronic device including the polyimide or the laminate.

Background Art

[0002] Conventionally, glass has been used as a substrate for displays such as liquid crystal displays and organic EL displays. However, when glass is thinned for weight reduction, there is a problem that its strength is insufficient and it is easily broken. Therefore, as an alternative to glass substrates, plastic substrates that are lightweight and have excellent flexibility have been proposed. In displays such as liquid crystal displays and organic EL displays, semiconductor elements such as TFTs are formed on the substrate to drive each pixel. Therefore, the substrate is required to have heat resistance and dimensional stability. Since polyimide films are excellent in heat resistance, chemical resistance, mechanical strength, electrical properties, dimensional stability, etc., they are expected as substrates for displays.

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

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

[0005] As mentioned above, Non-Patent Documents 1 and 2 report on the effect of the polyimide interface on TFT characteristics, but they do not specifically evaluate the interface state density where negative charges can exist. Furthermore, there is no detailed description of the polyimide, and there is no data on evaluating TFT characteristics with different polyimide substrates, so information on suitable polyimides for substrates remains unknown.

[0006] One method for evaluating the energy level density on the surface of insulating films such as polyimide is to measure the capacitance-voltage characteristics (hereinafter referred to as CV characteristics). Generally, it is 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 presence of energy level density at the semiconductor-insulating film interface. Therefore, it is necessary to provide polyimide with excellent CV characteristics in order to evaluate CV characteristics that affect device characteristics such as TFT characteristics, to develop polyimide films that are optimal as substrates for semiconductor devices and electronic devices including displays, and to further expand the applications of polyimide.

[0007] The present invention aims to provide polyimides exhibiting excellent CV properties, particularly polyimides in film form, laminated substrates using such polyimides, and electronic devices such as flexible displays containing these. [Means for solving the problem]

[0008] This invention relates to the following matters.

[0009] 1. A polyimide film for flexible electronic devices formed from polyimide that exhibits a maximum gradient of 0.005 / V or greater when capacitance-voltage measurement is performed on a laminate formed by creating a polyimide film with a thickness of 0.75 μm on a silicon wafer with a resistance of 4 Ω cm. (However, the maximum gradient refers to the maximum absolute value of the gradient in the normalized capacitance-voltage curve during the third positive scan, when capacitance measurement is performed while applying a DC voltage to the polyimide film on the silicon wafer between the lowest voltage V1 and the highest voltage V2, with a positive scan from the lowest voltage V1 to the highest voltage V2 and a negative scan from the highest voltage V2 to the lowest voltage V1. Here, the lowest voltage V1 is the voltage at which the capacitance of the polyimide film alone is observed, and the normalized capacitance-voltage curve is normalized with the capacitance at the lowest voltage V1 set to 1.)

[0010] 2. The polyimide film for flexible electronic devices according to item 1 above, characterized in that the weight fraction of imide groups (-CONCO-) in the repeating units of the polyimide 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-terminated groups in the entire polyimide, calculated from the charging ratio, is 29 μmol / g or less.

[0012] 4. A tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic acid 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 Diamine component (B) containing and A polyimide precursor containing repeating units obtained by the reaction (wherein the diamine component (B) is 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 above, wherein the diamine component (B) contains the diamine (B-1) and the diamine (B-2) together in a proportion of 40 mol% or more.

[0014] 6. The polyimide precursor according to item 4, characterized in that the total proportion of repeating units derived from 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and the diamine (B-1), and the total proportion of repeating units derived from 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and the diamine (B-2) is 40 mol% or more.

[0015] 7. A polyimide obtained by imidizing a polyimide precursor described in any one of items 4 to 6 above.

[0016] 8. A polyimide film, which is a film form of the polyimide described in item 7 above.

[0017] 9. A flexible electronic device comprising the polyimide film described in any one of items 1 to 3 above. 10. The flexible electronic device according to item 9, wherein the polyimide film is the polyimide film described in item 8 above.

[0018] 11. A method for manufacturing a flexible electronic device as described in item 9 or 10 above, The process involves applying a polyimide precursor solution or a polyimide precursor solution composition onto a carrier substrate and imidizing it to form a laminate having the carrier substrate and a polyimide film. A manufacturing method characterized by the following.

[0019] In addition to the matters described above, this 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 measurement is performed on a laminate formed by creating a polyimide film with a thickness of 0.75 μm on a silicon wafer with a resistance of 4 Ω cm (wherein the maximum gradient is the maximum absolute value of the gradient in the normalized capacitance-voltage curve at the third positive scan, when capacitance measurement is performed while applying a DC voltage to the polyimide film on the silicon wafer between a minimum voltage V1 and a maximum voltage V2, with a positive scan from the minimum voltage V1 to the maximum voltage V2 and a negative scan from the maximum voltage V2 to the minimum voltage V1. Herein, 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 with the capacitance at the minimum voltage V1 set to 1).

[0021] 2. The polyimide according to item 1 above, characterized in that 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 above, characterized in that the concentration of amine-terminated groups in the entire polyimide, calculated from the charging ratio, is 29 μmol / g or less.

[0023] 4. A tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic acid 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 Diamine component (B) containing and A polyimide precursor containing repeating units obtained by reaction.

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

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

[0026] 7. A polyimide obtained by imidizing a polyimide precursor described in any one of items 4 to 6 above.

[0027] 8. A polyimide precursor solution that yields the polyimide described in any one of items 1 to 3 above.

[0028] 9. A polyimide solution that yields the polyimide described in any one of items 1 to 3 above.

[0029] 10. A method for producing a polyimide solution, characterized by imidizing the polyimide precursor solution described in item 8 above.

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

[0031] 12. A laminate having a substrate and the polyimide film described in item 11 above.

[0032] 13. A substrate containing the polyimide film described in item 11 above, used for electronic device applications.

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

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

[0035] According to the present invention, it is possible to provide polyimides exhibiting excellent CV properties, particularly polyimides in film form, laminated substrates using such polyimides, and electronic devices such as flexible displays containing these, particularly flexible electronic devices.

[0036] Because the polyimide film of the present invention has excellent CV properties, even when used as a substrate for semiconductor devices such as TFTs, there is little concern about it affecting the performance of the semiconductor device, and in particular, there is little concern about changes or degradation of device characteristics such as shifts in switching characteristics due to long-term use. [Brief explanation of the drawing]

[0037] [Figure 1] This is a schematic diagram of a system for measuring the CV properties of polyimide. [Figure 2] This diagram illustrates how to determine the maximum gradient from the CV characteristics. [Modes for carrying out 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 this 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, and 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 manifested. In the embodiment of the present invention, it is -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 a voltage 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, a scanning range of -40V to 40V is used.

[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 the 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 changed depending on the application of the polyimide film (i.e., to match the frequency range of interest), but for display applications, measurements should be taken at frequencies in the range of 100Hz to 1MHz, particularly 500Hz to 10kHz. In the embodiment of this invention, 2.5kHz was used. The amplitude can be any voltage that is sufficiently smaller than the DC voltage and can be selected as appropriate, but in the embodiment of this invention, it was set to 0.1V.

[0042] In this invention, when evaluating the CV measurement results, the properties of polyimide are evaluated using a normalized capacitance-voltage curve (normalized CV curve) obtained by normalizing the measured CV curve by setting the capacitance value at the lowest voltage V1 to 1. This is to evaluate factors that affect semiconductors, such as interface states, while excluding differences in capacitance values ​​due to errors in the thickness of the polyimide film and differences in dielectric constant. Regarding the thickness of the polyimide film to be measured, in order to minimize evaluation errors, it is preferable to target a thickness of 0.65 μm to 0.85 μm, and particularly 0.75 μm, in the evaluation of this application.

[0043] In such a measurement system, when the DC voltage is scanned in the forward direction from the lowest voltage V1 to the highest voltage V2 (however, this is the third forward scan), as shown in Figure 2, typically, after passing the first flat region, a first decreasing region appears where the capacitance decreases relatively large, followed by a relatively flat region. Next, when the voltage is scanned in the negative direction from the highest voltage V2 to the lowest voltage V1, typically, the regions are observed in the reverse order of the forward scan. However, this does not coincide with the curve of the forward scan, and hysteresis is often observed.

[0044] The aforementioned "first depletion region" 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 (negative and with the largest absolute value) in the first depletion region is defined as the "maximum gradient." Therefore, the "maximum gradient" can be obtained as the absolute value of the peak of the negative value that appears in the differential curve of the normalized CV curve.

[0045] The polyimide of the present invention, when used as a 0.75 μm thick film on a silicon wafer with a resistivity of 4 Ωcm, exhibits a "maximum gradient" of 0.005 / V or greater, preferably greater than 0.007 / V, obtained by the CV measurement described above. The maximum gradient is larger (larger absolute value) as the interface state density decreases. While the interface state density is thought to be influenced by the surface state of the polyimide (e.g., composition, functional groups (especially surface functional groups), presence of impurities or additives, etc.), in the present invention, the surface state of the polyimide at the interface with the semiconductor is extremely favorable, and therefore it can be estimated to have a large "maximum gradient". Due to having such a large "maximum gradient", even when the polyimide of the present invention is used in electronic devices such as displays, it has little adverse effect on the operation and durability of the electronic device.

[0046] No polyimides focusing on such CV properties have been reported, nor have any such developments actually been carried out. Naturally, existing polyimides do not satisfy the aforementioned CV properties. Furthermore, since CV properties are thought to be influenced by the surface state of the polyimide, it would mean that any chemical structure of the polyimide is acceptable as long as the CV properties are satisfied.

[0047] <<Polyimides, polyimide precursors>> The polyimide or its precursor (polyimide precursor) of the present invention is not particularly limited in its chemical structure as long as it satisfies the CV properties, and the chemical structure can be appropriately selected according to the function to be imparted. The polyimide precursor is given 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 independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group.) It has repeating units represented by . Particularly preferred are polyamic acids in which R1 and R2 are hydrogen atoms. Also, polymers in which partial imidization has progressed, 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 "polyimide precursors" and "polyamic acids" (in which the remaining R1 and R2 are hydrogen atoms).

[0049] Furthermore, polyimide is given 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 repeating units represented by .

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

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

[0058]

Chemical formula

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

[0060] Specific examples of Z5 include aromatic hydrocarbon groups 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] [Chemical formula] (In the formula, Z1 is a direct bond or a hexafluoroisopropylidene bond.)

[0063] Here, since the obtained polyimide material can achieve high heat resistance, high transparency, and low linear thermal expansion coefficient simultaneously, it is more preferable that Z1 is a direct bond.

[0064] In addition, as a preferable group, in the above formula (9), when Z1 is the following formula (3A):

[0065] [Chemical formula] Compounds in which it is a fluorene-containing group represented by are exemplified. Z 11 and Z 12 are each independently, preferably the same, a single bond or a divalent organic group. Z 11 and Z 12 are preferably an organic group containing an aromatic ring. For example, the formula (3A1):

[0066] [Chemical formula] (Z 13 and Z 14 are each independently a single bond, -COO-, -OCO- or -O-. Here, when Z 14 is bonded to the fluorene group, Z 13 is preferably -COO-, -OCO- or -O- and Z 14 is preferably a single bond structure; R 91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably methyl, n is an integer of 0 to 4, preferably 1.) The structure represented by is preferable.

[0067] Examples of tetracarboxylic acid components that give a repeating unit 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 sulfonyl diphthalic acid, and these dianhydrides are preferably used as monomers. Examples of tetracarboxylic acid components that give a repeating unit of general formula (II) in which X1 is a tetravalent group having an aromatic ring containing a fluorine atom include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride. Furthermore, a 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 components may be used alone or in combination of multiple types.

[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 aliphatic 4 to 12-membered ring, more preferably an aliphatic 4-membered ring or an aliphatic 6-membered ring. The following are examples of tetravalent groups having preferred aliphatic 4-membered rings or aliphatic 6-membered rings.

[0069] [ka] (In the formula, R 31 ~R 38These are either directly bonded or divalent organic groups. 41 ~R 47 Each of these independently represents one selected from the group consisting of groups represented by the formulas: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-. 48 (This refers to an organic group containing an aromatic ring or alicyclic structure.)

[0070] R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 , R 38 Specifically, these include direct bonds, aliphatic hydrocarbon groups having 1 to 6 carbon atoms, oxygen atoms (-O-), sulfur atoms (-S-), carbonyl bonds, ester bonds, and amide bonds.

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

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

[0073] Specifically, W1 can be a direct bond, a divalent group represented by formula (5) below, or a divalent group represented by formula (6) below.

[0074] [ka] (R in equation (6)) 61 ~R 68Each of these independently represents either a directly bonded group or a divalent group represented by formula (5) above.

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

[0076] [ka]

[0077] Examples of tetracarboxylic acid components that give the repeating unit of formula (II) where X1 is a tetravalent group having an alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic acid, isopropylidene diphenoxybisphthalic 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]octa-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]deca-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, tetracarboxylic acid chlorides, etc. 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 from 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 of these independently represents either a directly bonded group or a divalent group represented by formula (5) above.

[0084] Here, since the resulting polyimide can achieve both high heat resistance, high transparency, and a low coefficient of linear thermal expansion, it is particularly preferable that W1 is directly bonded or selected from the group consisting of groups represented by the formulas: -NHCO-, -CONH-, -COO-, and -OCO-. Also, if W1 is R 61 ~R 68 It is also particularly preferable that the group is directly bonded, or is one of the divalent groups represented by formula (6) selected from the group consisting of groups represented by formula: -NHCO-, -CONH-, -COO-, and -OCO-.

[0085] In addition, a preferred group is one in formula (4) above where W1 is given by the following formula (3B):

[0086] [ka] Examples of compounds containing a fluorenyl group represented by Z include Z 11 and Z 12 Each of these is independently, preferably identical, and is a single-bonded or divalent organic group. 11 and Z 12 As such, organic groups containing aromatic rings are preferred, for example, formula (3B1):

[0087] [ka] (Z 13 and Z 14 These are independent single bonds, -COO-, -OCO-, or -O-, where Z 14 When bonded to the fluorenyl group, Z 13 Z is -COO-, -OCO-, or -O- 14A single bond structure is preferred; R 91 (where n is an alkyl group or phenyl group having 1 to 4 carbon atoms, preferably phenyl, and n is an integer from 0 to 4, preferably 1.) A structure represented by is preferred.

[0088] Other preferred groups include compounds in formula (4) above in which W1 is a phenylene group, i.e., terphenyldiamine compounds, and compounds in which all are para bonds are particularly preferred.

[0089] Another preferred group is, in formula (4) above, where W1 is in the structure of the first phenyl ring in formula (6), R 61 and R 62 Examples include compounds in which the group is a 2,2-propyridene group.

[0090] Another preferred base is the one in formula (4) above, where W1 is the following formula (3B2):

[0091] [ka] Examples of compounds represented by [the formula shown] are given.

[0092] Examples of diamine components that give the repeating unit of general formula (II) where 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 Noxy-4-diaminobenzoate, bis(4-aminophenyl) terephthalate, biphenyl-4,4'-dicarboxylic acid bis(4-aminophenyl) ester, p-phenylenebis(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-aminobenzoate) (Nophenoxy)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 include 5-triazine, 2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-triazine, and 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine. Examples of diamine components that give the repeating unit 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. In addition, 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 individually 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 aliphatic 4 to 12-membered ring, more preferably an aliphatic 6-membered ring.

[0094] Examples of divalent groups having an alicyclic structure include the following:

[0095] [ka] (In the formula, V1 and V2 are each independently directly bonded or are divalent organic groups, n 21 ~n 26 Each of these independently represents an integer from 0 to 4, and R 81 ~R 86 Each of these is 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 (Each of these groups is independently selected from the group consisting of groups represented by the formulas: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-.)

[0096] Specifically, V1 and V2 include direct bonds and divalent groups represented by formula (5) above.

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

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

[0099] [ka]

[0100] Examples of diamine components that give the repeating unit of general formula (II) where 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, 1 Examples 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'-spirobindan, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobindan. The diamine components may be used individually or in combination of multiple types.

[0101] In addition to the tetracarboxylic acid and diamine components mentioned above, it is also preferable to add a carboxylic acid monoanhydride and proceed with the reaction. The carboxylic acid monoanhydride is preferably a dicarboxylic acid monoanhydride, but may also be an aromatic carboxylic acid monoanhydride or an aliphatic carboxylic acid monoanhydride. Aromatic carboxylic acid monoanhydrides are particularly preferred. The aromatic carboxylic acid monoanhydride is preferably one having an aromatic ring with 6 to 30 carbon atoms, more preferably one having an aromatic ring with 6 to 15 carbon atoms, and even more preferably one having an aromatic ring with 6 to 10 carbon atoms.

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

[0103] When adding a carboxylic acid monoanhydride, it is more preferable that the following formulas (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 higher, the molecular weight of the polyimide precursor (especially polyamic acid) is increased, improving the strength and heat resistance of the resulting polyimide film. X / Y is preferably 0.98 or higher. If X / Y is less than 1.00, the diamine component is in excess of the tetracarboxylic acid component. This allows for the formation of amino groups that can be end-canceled with carboxylic acid monoanhydrides. X / Y is preferably 0.99 or lower.

[0106] Furthermore, (Z / 2) / (YX) represents the molar ratio of carboxylic acid monoanhydride to end-capable amino groups. When X / Y is less than 1.00 and (Z / 2) / (YX) is 0.5 or more, the end-capability of the polyimide precursor can be increased, and the CV properties can be improved. A (Z / 2) / (YX) value closer to 1 is preferable. (Z / 2) / (YX) is preferably 0.6 or more, more preferably 0.7 or more. When (Z / 2) / (YX) is 1.05 or less, the amount of free carboxylic acid monoanhydride can be reduced, and the strength and CV properties of the resulting polyimide film can be improved. (Z / 2) / (YX) is preferably 1.03 or less, more preferably 1.01 or less.

[0107] In one embodiment of the present invention, it is preferable that the weight fraction of the imide group (-C(O)NC(O)-) in the polyimide repeating unit (i.e., the general formula II) is less than 38.3% by weight. In a particular embodiment, it is more preferable that it is 30% by weight or less.

[0108] Here, the polyimide may be a copolymer, meaning that at least one of the tetracarboxylic acid component and the diamine component giving the polyimide may contain two or more compounds. In this case, the weight fraction of the imide group is calculated using a weighted average based on the proportion of monomers used. The weight fraction of groups other than the imide group is calculated similarly. In the following description, when the weight fraction of a particular group is referred to, the polyimide includes both homopolymers and copolymers.

[0109] In one embodiment of the present invention, it is preferable that the weight fraction of functional groups in the polyimide repeating unit be small. The "functional groups in the repeating unit" as defined herein are the parts of the polyimide repeating unit other than the aromatic ring and saturated alkyl chain, and include -O- (ether linkage), -CO- (carbonyl group), -COO- (ester), -SO2-, etc. F and Cl, which substitute hydrogen atoms in the aromatic ring and saturated alkyl chain, are not included in the "functional groups in the repeating unit".

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

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

[0112] In one preferred embodiment of the present invention, the tetracarboxylic acid component forming the repeating unit preferably includes compounds selected from tetracarboxylic dianhydrides having a fluorene structure within the molecule, and tetracarboxylic dianhydrides having three or more benzene rings for each functional group other than the two acid anhydride groups (the group corresponding to the "functional group in the repeating unit"). Compounds that do not have a functional group corresponding to the "functional group in the repeating unit" in addition to the two acid anhydride groups are also included in the preferred compounds, in which case the number of benzene rings is preferably two or more, and more preferably three or more.

[0113] In one preferred embodiment of the present invention, the diamine component forming the repeating unit preferably includes compounds selected from diamines having a fluorene structure within the molecule and diamines having three or more benzene rings for each functional group other than the two amine groups (the group corresponding to the "functional group in the repeating unit"). Compounds that do not have a functional group corresponding to the "functional group in the repeating unit" in addition to the two amine groups are also included in the preferred compounds, in which case the number of benzene rings is preferably two or more, and more preferably three or more.

[0114] In one preferred embodiment of the present invention, it is preferable that each of the tetracarboxylic acid component and the diamine component forming the repeating unit includes a compound selected from the above conditions, namely a compound having a fluorene structure in the molecule and a compound having three or more benzene rings for each "functional group in the repeating unit" (including the case with zero functional groups).

[0115] In one embodiment of the present invention, a small amount of terminal functional groups is also preferred. The amount of terminal functional groups is calculated based on the charging ratio of the tetracarboxylic acid component and the diamine component when producing polyimide (when producing polyamic acid), the purity of each component, the amount of terminal encapsulant added, and the amount of reactive additive added. The calculation of the amount of terminal functional groups from the charging ratio of the tetracarboxylic acid component and the diamine component is performed as follows.

[0116] The degree of polymerization of polyimide obtained with a tetracarboxylic dianhydride / diamine ratio of 1 is theoretically infinite, so the terminal groups are assumed to be 1 / ∞ = 0. If the tetracarboxylic dianhydride and diamine are not equimolar, and taking the case where diamine is in excess as an example, theoretically, a polyimide with a degree of polymerization n and the structure of formula (II-B) can be obtained. n is, (Formula) Tetracarboxylic acid dianhydride / diamine ratio = n / (n+1) This can be obtained by finding n that satisfies the following condition. Let a be the formula weight of the repeating unit, and let a be the molecular weight of one terminal diamine. b Therefore, the formula weight of a polyimide with a degree of polymerization n is (a*n+a b Therefore, the amount of terminal amine is 2 / (a*n+a b [Unit: mol / g] It can be calculated as follows. In the examples of this application, it 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 total amount of 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 the imide group and the functional group in the repeating unit is preferably 30% by weight or less, and the amount of terminal functional groups is preferably 20 μmol / g or less. In another preferred embodiment, the combined weight fraction of the imide group and the functional group in the repeating unit is preferably 40% by weight or less, and the amount of terminal functional groups is preferably 10.5 μmol / g or less. It is also very preferred that the combined weight fraction of the imide group and the functional group in the repeating unit is 30% by weight or less, and the amount of terminal functional groups is preferably 10.5 μmol / g or less.

[0120] Controlling the functional groups (imide groups, functional groups in repeating units, terminal functional groups) in the polyimide as described above is a factor to consider when obtaining the polyimide having the CV properties of the present invention.

[0121] <<Novel polyimide precursors and polyimides>> This application also discloses polyimide precursors and polyimides containing novel structures. The novel polyimide precursors and polyimides are A tetracarboxylic acid component (A) containing at least 3,3',4,4'-biphenyltetracarboxylic acid 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 It contains repeating units obtained by reacting a diamine component (B) containing the above. That is, in general formulas I and II, it contains repeating units in which 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) in a proportion of 40 mol% or more. In addition to s-BPDA, the tetracarboxylic acid component (A) may also preferably contain (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate). Other tetracarboxylic acid dianhydrides listed above may also be included. For example, compounds selected from tetracarboxylic acid dianhydrides having a fluorene structure in the molecule, and tetracarboxylic acid dianhydrides having three or more benzene rings for each functional group other than the two acid anhydride groups (groups corresponding to "functional groups in repeating units") may be included. 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) together in a proportion of 40 mol% or more. In addition, 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, it may contain compounds selected from diamines having a fluorene structure in the molecule and diamines having three or more benzene rings for each functional group other than the two amine groups (the group corresponding to the "functional group in the repeating unit"). Preferred compounds include 1,1':4',1”:4”,1”'-quarterphenyl-4,4”'-diamine. The amount of 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 be 0 mol%.

[0124] Furthermore, it is preferable that the total proportion of repeating units derived from s-BPDA and (B-1) diamine and repeating units derived from s-BPDA and (B-2) diamine in the polyimide precursor or polyimide repeating units is 40 mol% or more.

[0125] This novel polyimide exhibits excellent CV properties, and it is preferable to select the combination compound, the tetracarboxylic dianhydride / diamine ratio, etc., such that at least one, preferably two, 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 aforementioned range (particularly preferred range).

[0126] <<Method for manufacturing polyimide film>> The following describes a method for manufacturing polyimide, particularly a method for manufacturing polyimide film via a laminate in which a polyimide film is formed on a carrier substrate.

[0127] A schematic example of a method for manufacturing polyimide films is as follows: (1) A method of forming a polyimide film by casting a polyimide precursor solution (especially polyamic acid) solution, or a polyimide precursor solution composition to which an imidation catalyst, dehydrating agent, inorganic fine particles, etc., are optionally added as needed, onto a carrier substrate, and then heating to dehydrate, cyclize, and desolvent (thermal imidation); (2) A method for forming a polyimide film by adding a cyclization catalyst and a dehydrating agent to a polyimide precursor (especially polyamic acid) solution, and further adding inorganic fine particles as needed, casting the polyimide precursor solution composition onto a carrier substrate, chemically dehydrating and cyclizing it, and then desolvating and imidizing it by heating (chemical imidization); (3) When polyimide is soluble in an organic solvent, a method of forming a polyimide film by casting a polyimide solution composition, to which additives such as inorganic fine particles are optionally added, onto a carrier substrate, and heating to a predetermined temperature while removing the solvent by heating. These are some examples.

[0128] <Polyimide precursor solution, polyimide solution> First, the preparation of the polyimide precursor solution and the polyimide solution will be described. The polyimide precursor solution or polyimide solution is 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 in which one of the components is in excess may be synthesized beforehand, and then the respective polyimide precursor solutions may be combined and mixed under reaction conditions.

[0129] The organic solvent is not particularly limited, but examples 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 solvents such as triethylene glycol; phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol; acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, and dimethyl sulfoxide. Furthermore, other common organic solvents, such as alcohol-based solvents like methanol and ethanol, as well as phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl Ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, N-methyl caprolactam, hexamethyl phosphorotriamide, 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, and biodegradable methyl lactate, ethyl lactate, and butyl lactate can also be used. One or more organic solvents may be used.

[0130] When carrying out polymerization reactions to obtain polyimide precursor solutions and polyimide solutions, respectively, the concentration of total monomers in the organic solvent (substantially equal to the solid content concentration of the polyimide precursor solution or polyimide solution) can be appropriately selected depending on the intended use or manufacturing purpose. The solid content concentration of the obtained 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, relative to the total amount of polyimide precursor or polyimide and solvent. If the solid content concentration is lower than 5% by mass, productivity and handling during use may be poor, and if it is higher than 45% by mass, the fluidity of the solution may be lost.

[0131] Furthermore, the 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, it will lose its fluidity, making uniform coating onto carrier substrates such as metal or glass difficult. If it is lower than 0.1 Pa·s, dripping or repelling may occur when coating onto carrier substrates such as metal or glass, and it may be difficult to obtain a polyimide film with high properties.

[0132] As an example of the production of a polyimide precursor solution, the polymerization reaction between 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 reacting them 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 the production of a polyimide solution, the polymerization reaction between the tetracarboxylic acid component and the diamine component can be carried out by a known method, for example, by mixing them in substantially equimolar amounts or with a slight excess of either component (acid component or diamine component). The polyimide solution can be obtained by carrying out the reaction at a reaction temperature of 140°C or higher, preferably 160°C or higher (preferably 250°C or lower, and even more preferably 230°C or lower) for about 1 to 60 hours.

[0134] Furthermore, when adding a carboxylic acid monoanhydride (especially a dicarboxylic acid monoanhydride) as described above, a method is generally preferred that includes a first step of reacting a tetracarboxylic acid component and a diamine component in a solvent, preferably in a molar ratio satisfying formula (1) above, to obtain a polyimide precursor (especially polyamic acid) having an amino group at its terminus, and a second step of subsequently adding and reacting a carboxylic acid monoanhydride, preferably in a molar ratio satisfying formula (2) above, to seal the terminus of the polyimide precursor (especially polyamic acid).

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

[0136] In the second step, the reaction temperature may be set as appropriate, but from the viewpoint of reliably sealing 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 obtained in this manner can be used as is, or, if necessary, after removing the organic solvent or adding a new organic solvent, for the production of polyimide films.

[0138] For thermal imidation, the polyimide precursor solution may contain, as necessary, an imidation catalyst, an organophosphorus-containing compound, inorganic fine particles, etc. For chemical imidation, the polyimide precursor solution may contain, as necessary, a cyclization catalyst, a dehydrating agent, inorganic fine particles, etc. The polyimide solution may contain, as necessary, inorganic fine particles, etc.

[0139] Examples of imidation catalysts include substituted or unsubstituted nitrogen-containing heterocyclic compounds, N-oxide compounds of said nitrogen-containing heterocyclic compounds, substituted or unsubstituted amino acid compounds, aromatic hydrocarbon compounds having a hydroxyl group, or aromatic heterocyclic compounds. 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 suitably used. The amount of imidation catalyst used is preferably 0.01 to 2 equivalents, particularly 0.02 to 1 equivalent, relative to the amide units of the polyamic acid. Using an imidation catalyst can improve the physical properties of the resulting polyimide film, especially its elongation and edge tear resistance.

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

[0141] Examples of cyclization catalysts 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 dehydrating agents 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 means can be applied to uniformly disperse these inorganic fine particles.

[0144] In one embodiment, it is preferable that the polyimide precursor solution or polyimide solution 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 properties of the polyimide film, as well as a decrease in adhesive strength and blistering of the laminate. Furthermore, adding or reacting a silane coupling agent with the polyimide precursor solution can also lead to a decrease in the viscosity stability of the polyimide precursor solution. To avoid these problems, it is preferable not to use a silane coupling agent.

[0145] <Manufacturing of laminates and electronic devices> In the manufacture of electronic devices, first, a polyimide precursor solution or a polyimide solution (including composition solutions containing additives as needed) is cast onto a carrier substrate, and a polyimide film is formed by imidization and desolvation (mainly desolvation in the case of a polyimide solution) by heat treatment, thereby obtaining a laminate of the carrier substrate and the polyimide film. There are no restrictions on the carrier substrate, but generally, glass substrates such as soda-lime glass, borosilicate glass, and alkali-free glass, or metal substrates such as iron, stainless steel, and copper are used. The method of casting the polyimide precursor solution and the polyimide solution onto the carrier substrate is not particularly limited, but examples of conventionally known methods include spin coating, screen printing, bar coating, and electrodeposition. The heat treatment conditions when using a polyimide precursor solution are not particularly limited, but for example, after drying in a temperature range of 50°C to 150°C, it is preferable to treat 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 also 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 may not be able to maintain sufficient mechanical strength and may break under stress, for example, when used as a substrate for a flexible device. Furthermore, the thickness of the polyimide film is 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 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 onto a carrier substrate such as a glass substrate. The peel strength between the carrier substrate such as a glass substrate and the polyimide film 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, when measured in accordance with JIS K6854-1.

[0148] Alternatively, 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 can be used as a water vapor barrier layer and is therefore preferred. Examples of water vapor barrier layers include silicon nitride (SiN). x ), silicon dioxide (SiO₂) x ), silicon oxynitride (SiO x N y Examples include inorganic films containing inorganic substances selected from the group consisting of metal oxides such as aluminum oxide (Al2O3), titanium oxide (TiO2), and zirconium oxide (ZrO2), as well as metal nitrides and metal oxynitrides. Generally, known methods for depositing these thin films include physical deposition methods such as vacuum deposition, sputtering, and ion plating, and chemical deposition methods such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD). This second layer can also consist of multiple layers. Even in the case of a device having a second layer on a polyimide film, the influence of the polyimide film may extend to the semiconductor layer via the second layer. Therefore, to improve device characteristics and durability, the polyimide with good CV characteristics of the present invention is preferably used.

[0149] A flexible device substrate may be formed by laminating a polyimide film onto a resin film or an inorganic film. The polyimide film can be laminated onto the resin film or inorganic film using a polyimide precursor solution or a polyimide solution, similar to the method used for carrier substrates.

[0150] The polyimide film obtained in this invention can be firmly laminated even when an inorganic film is used as the substrate. The peel strength between the polyimide film and the inorganic film (e.g., silicon oxide film), when 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 a formed laminate (particularly a polyimide film). The elements and circuits to be formed, as well as the manufacturing process, vary depending on the type of device. When manufacturing a TFT liquid crystal display device, for example, an amorphous silicon TFT is formed on a 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. On top of this, structures necessary for a liquid crystal display can be formed by known methods. Since the polyimide film obtained in this invention has excellent properties such as heat resistance and toughness, the method for forming circuits and the like is not particularly limited.

[0152] When used as an electronic device, specifically a flexible device, the device substrate (particularly a polyimide film) on which circuits and other structures are formed on its surface is peeled off from the carrier substrate. There are no particular restrictions on the peeling method; for example, it can be carried out by laser peeling, where a laser is irradiated from the carrier substrate side, or by mechanical peeling.

[0153] The polyimide and polyimide film of the present invention (including those with a second layer such as a resin film or inorganic film laminated thereon) are particularly suitable as substrates for electronic devices where thinning and flexibility are desired. Here, "flexible (electronic) device" means that the device itself is flexible, and typically, a semiconductor layer (such as transistors and diodes as elements) is formed on the substrate to complete the device. It does not refer to conventional FPCs (flexible printed circuit boards) on which "rigid" semiconductor elements such as IC chips are mounted, such as COF (Chip On Film). Flexible (electronic) devices in which the polyimide and polyimide film of the present invention described above and below are suitably used include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as light-receiving devices such as solar cells and CMOS.

[0154] The polyimide of the present invention can be used in a variety of applications, but in order to achieve excellent CV properties, it is preferable to use it in devices in which the polyimide and semiconductor are in direct contact, or in devices in which they are laminated via a thin film (for example, a thin film of 200 nm or less, preferably 100 nm or less, such as the second layer described above).

[0155] Furthermore, although the above description explains a method of forming elements and circuits on a laminate of polyimide film and carrier substrate, elements and circuits may also be formed on a single polyimide film if there are no obstacles to forming the elements and circuits.

[0156] Examples of semiconductors include single-crystal silicon, amorphous silicon, and polysilicon (these may be p-type or n-type doped with impurities), as well as gallium nitride-based and other compound semiconductors. [Examples]

[0157] The present invention will be described in more detail below using examples. However, 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. Note that 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 by 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 approximate value of the derivative function of the normalized C-V curve, the normalized capacitance C n1 at a certain voltage V n1 and the normalized capacitance C n1 at V n2 which is V + 1.5 [V] n2 are used to calculate the absolute value "|(C n2 - C n1 ) / (V n2 - V n1 )|". This value is calculated for the entire normalized C-V curve, and the maximum value of |(C n2 - C n1 ) / (V n2 - V n1 )| is adopted as the gradient of the composition.

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

[0162] Monomer A: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (formula weight 294.22), purity (%) 99.9 Monomer A2: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (molecule 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'-diyrbis(oxy))diamine (molecule 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 Additives: 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-in-1-yl)isobenzofuran-1,3-dione (formula weight 276.23), purity: 99.8% Monomer L: 5,5'-(ethyn-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) In a reaction vessel purged with nitrogen gas, 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 were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 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 a further 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) In a reaction vessel purged with nitrogen gas, [1,1':4',1”-terphenyl]-4,4”-diamine (50 mol%) and 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine (50 mol%) and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 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 a further 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) In a reaction vessel purged with nitrogen gas, [1,1':4',1”-terphenyl]-4,4”-diamine (50 mol%) and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine (50 mol%) and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 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 a further 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) In a reaction vessel purged with nitrogen gas, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (50 mol%), 9,9-bis(4-aminophenyl)fluorene (50 mol%), and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (100 mol%) was added and stirred for a further 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) In a reaction vessel purged with nitrogen gas, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (50 mol%), 9,9-bis(4-aminophenyl)fluorene (50 mol%), and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (100 mol%) was added and stirred for a further 30 minutes to obtain a polyamic acid solution. After that, the temperature was raised to 190°C and held for 3 hours to carry out imidation, obtaining 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) In a reaction vessel purged with nitrogen gas, 1,4-diaminobenzene (100 mol%) and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (100 mol%) was added and stirred for a further 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) In a reaction vessel purged with nitrogen gas, 1,4-diaminobenzene (100 mol%) and NMP were charged and 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 a further 30 minutes. Subsequently, phthalic anhydride (4 mol%) was added and stirred for a further 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) In a reaction vessel purged with nitrogen gas, 1,4-diaminobenzene (100 mol%) and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (99.5 mol%) and 3-aminopropyltriethoxysilane (0.05 parts relative to the total amount of monomers) were added, and the mixture was stirred for a further 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) In a reaction vessel purged with nitrogen gas, 1,4-diaminobenzene (100 mol%) and NMP were charged and 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 a further 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) In a reaction vessel purged with nitrogen gas, 1,4-diaminobenzene (100 mol%) and NMP were charged and heated and stirred at 40°C for 15 minutes to dissolve the monomers. Then, 3,3',4,4'-tetracarboxylic biphenyl dianhydride (monomer A2; low purity) (100 mol%) was added and stirred for a further 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution) with a viscosity of 480 Pa·s (25°C).

[0180] <Examples 1-3> A polyimide film with a thickness of 0.75 μm was formed by spin-coating a 6-inch silicon wafer (625 μm thick, resistivity 4 Ωcm, p-type (boron impurity)) with a further diluted solution of the polyamic acid prepared in Reference Examples 1-3, and then heat-treating it at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and at 330°C for 5 minutes. The results of CV measurements performed on the obtained polyimide film and the compositions of the reference examples used are shown in Table 1.

[0181] <Example 4> Similar to Example 1, a further diluted solution of the polyamic acid solution prepared in Reference Example 4 was spin-coated onto a 6-inch silicon wafer. The wafer was then heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and 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> Similar to Example 1, a further diluted solution of the polyimide solution prepared in Reference Example 5 was spin-coated onto a 6-inch silicon wafer. The wafer was then heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and 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, 7, Comparative Examples 1, 2, 3> Similar to Example 1, a further diluted solution of the polyamic acid prepared in Reference Examples 6, 7, 8, 9, and 10 was spin-coated onto a 6-inch silicon wafer. The wafer was then heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each, and 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, similar 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. Then, tetracarboxylic dianhydride was added and the mixture was stirred for 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution). However, in the examples where an end encapsulant was added (Reference Examples 16 to 18), similar to Reference Example 7, the end encapsulant was added and the mixture was stirred for a further 30 minutes to obtain a liquid polyimide precursor resin composition (polyamic acid solution).

[0186] [Reference Example 11] (Composition of Example 8) (Monomer A 70 / Monomer M 30 / / Monomer C 100) Tetracarboxylic acid 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℃)

[0187] [Reference Example 12] (Composition of Example 9) (Monomer A 70 / Monomer N 30 / / Monomer C 100) Tetracarboxylic acid dianhydride: 3,3',4,4'-tetracarboxylic acid 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℃)

[0188] [Reference Example 13] (Composition of Example 10) (Monomer A 70 / Monomer O 30 / / Monomer C 100) Tetracarboxylic acid 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℃)

[0189] [Reference Example 14] (Composition of Example 11) (Monomer A 100 / / Monomer C 70 / Monomer P 30) Tetracarboxylic acid dianhydride: 3,3',4,4'-tetracarboxylic acid 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℃)

[0190] [Reference Example 15] (Composition of Example 12) (Monomer A 100 / / Monomer C 70 / Monomer Q 30) Tetracarboxylic acid dianhydride: 3,3',4,4'-tetracarboxylic acid 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] [[ID=3^4]][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-cap encapsulant: 5,5'-(ethyn-1,2-diyl)bis(isobenzofuran-1,3-dione) (monomer L) (2 mol%) (Note: Although monomer L is a tetracarboxylic dianhydride, it was added last, similar to the end-cap encapsulant.) Viscosity of the obtained liquid polyimide precursor resin composition (polyamic acid solution): 3.11 Pa·s (25℃)

[0194] [Reference Example 19] (Composition of Comparative Example 4) (Monomer A 30 / Monomer R 70 / / Monomer C 100) Tetracarboxylic acid dianhydride: 3,3',4,4'-tetracarboxylic acid 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℃)

[0195] [Reference Example 20] (Composition of Comparative Example 5) (Monomer A 68.6 / Monomer M 29.4 / Monomer C 100) Tetracarboxylic acid 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℃)

[0196] [Reference Example 21] (Composition of Comparative Example 6) (Monomer A 68.6 / Monomer N 29.4 / Monomer C 100) Tetracarboxylic acid 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℃)

[0197] [Reference Example 22] (Composition of Comparative Example 7) (Monomer A 68.6 / Monomer O 29.4 / Monomer C 100) Tetracarboxylic acid 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℃)

[0198] [Reference Example 23] (Composition of Comparative Example 8) (Monomer A 98 / / Monomer C 70 / Monomer P 30) Tetracarboxylic acid 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℃)

[0199] [Reference Example 24] (Composition of Comparative Example 9) (Monomer A 98 / / Monomer C 70 / Monomer Q 30) Tetracarboxylic acid 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, Comparative Examples 5 to 9> Using the polyamic acid solutions prepared in Reference Examples 11 to 18 and Reference Examples 20 to 24, under the same conditions as in Example 4, that is, a solution obtained by further diluting the polyamic acid solution was spin-coated on a 6-inch silicon wafer and heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each and at 360°C for 5 minutes to form a polyimide film with a thickness of 0.75 μm. The results are shown in Table 2.

[0201] <Comparative Example 4> Using the polyamic acid solution prepared in Reference Example 19, under the same conditions as in Example 6, that is, a solution obtained by further diluting the polyamic acid solution was spin-coated on a 6-inch silicon wafer and heat-treated at 120°C, 150°C, 200°C, and 250°C for 10 minutes each and 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, samples exactly the same as those in Example 6 and Comparative Example 1, respectively, were prepared, and the influence of the scanning speed of the DC voltage during the measurement of the C-V characteristics was confirmed. The maximum gradients of Example 16 and Comparative Example 10 in which the scanning speed of the DC voltage during the measurement of the C-V 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 with a scanning speed of 0.25 V / sec.

[0203]

Table 2

Industrial Applicability

[0204] The polyimide of the present invention is suitably used in electronic device applications, such as substrates for flexible devices. [Explanation of symbols]

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

Claims

1. A flexible electronic device substrate formed of a polyimide (excluding polyimides containing a Si-containing group) 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 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, performing a positive scan from the minimum voltage V1 to the maximum voltage V2 and a negative scan from the maximum voltage V2 to the minimum voltage V1. Here, the minimum voltage V1 is the voltage at which the capacitance of only the polyimide film is observed, and the normalized capacitance-voltage curve is normalized such that the capacitance at the minimum voltage V1 is set to 1.)

2. 2. The flexible electronic device substrate according to claim 1, wherein the weight fraction of imide groups (-CONCO-) in the repeating units of the polyimide is less than 38.3 wt %.

3. 3. The flexible electronic device substrate according to claim 1, wherein the concentration of amine terminal groups in the entire polyimide calculated from the charge ratio is 29 μmol / g or less.

4. A flexible electronic device comprising the flexible electronic device substrate according to any one of claims 1 to 3.

5. A method for manufacturing a flexible electronic device substrate according to any one of claims 1 to 3, comprising: a step of applying a polyimide precursor solution or a polyimide precursor solution composition that provides a polyimide as defined in any one of claims 1 to 3 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:

6. A method for manufacturing a flexible electronic device, which includes the method for manufacturing a flexible electronic device substrate described in claim 5 as one step.

7. A method for manufacturing a flexible electronic device as described in claim 6, comprising a step of peeling the flexible electronic device substrate from the carrier substrate.

Images