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

Abstract

Provided is a polyimide precursor composition with which it is possible to manufacture a polyimide film that has excellent thermal characteristics and / or thermal resistance, and that has excellent transparency. The polyimide precursor composition comprises a repeating unit including a repeating unit expressed by the following general Formula (I) and a repeating unit obtained by further imidizing the general Formula (I), and contains a polyimide precursor having an imidization ratio of more than 0% and less than 50% and a solvent. (where 70 mol% or more of X1 is a structure expressed by Formula (1-1), and 70 mol% or more of Y1 is a structure expressed by Formula (D-1) and / or (D-2).)

Description

[Technical field]

[0001] The present invention relates to a polyimide precursor composition suitable for use in electronic devices such as substrates for flexible devices, a polyimide film having improved properties, and a polyimide film / substrate laminate, and a method for producing a flexible electronic device using the composition. [Background technology]

[0002] Polyimide films have been widely used in fields such as electric and electronic devices and semiconductors due to their excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability. Meanwhile, in recent years, with the advent of an advanced information society, the development of optical materials such as optical fibers and optical waveguides in the optical communications field, and liquid crystal alignment films and protective films for color filters in the display device field has progressed. In particular, in the display device field, there has been active research into lightweight and flexible plastic substrates as an alternative to glass substrates, and the development of displays that can be bent or rolled.

[0003] Displays such as liquid crystal displays and organic electroluminescence displays use semiconductor elements such as TFTs to drive each pixel. This requires heat resistance and dimensional stability in the substrate. Polyimide film is promising as a substrate for displays because it has excellent heat resistance, chemical resistance, mechanical strength, electrical properties, and dimensional stability.

[0004] Polyimide is generally colored yellowish brown, which limits its use in transparent devices such as backlit liquid crystal displays. However, in recent years, polyimide films with excellent mechanical and thermal properties as well as transparency have been developed, raising expectations for their use as substrates for displays (see Patent Documents 1 to 3).

[0005] In general, it is difficult to maintain the planarity of a flexible film, and therefore it is difficult to uniformly and precisely form semiconductor elements such as TFTs, fine wiring, etc., on a flexible film. For example, Patent Document 4 describes "a method for manufacturing a flexible device, which is a display device or a light-receiving device, including the steps of forming a solid polyimide resin film by applying a specific precursor resin composition onto a carrier substrate, forming a circuit on the resin film, and peeling off the solid resin film having the circuit formed on its surface from the carrier substrate."

[0006] Patent Document 5 discloses a method for producing a flexible device, which includes forming a polyimide film on a glass substrate to obtain a polyimide film / glass substrate laminate, forming elements and circuits required for the device on the polyimide film / glass substrate laminate, and then irradiating a laser from the glass substrate side to peel off the glass substrate.

[0007] Patent Document 6 discloses a polyimide precursor composition containing a repeating unit derived from a compound in which one of a tetracarboxylic acid component and a diamine component has an alicyclic structure and the other has an aromatic ring, a polyimide precursor composition containing an imidazole compound, and the use of this polyimide precursor composition to produce a polyimide film / glass substrate laminate. The polyimide film obtained by the invention of Patent Document 6 has a small thickness direction phase difference (retardation), excellent mechanical properties, and excellent transparency.

[0008] Patent Document 7 describes a polyimide precursor obtained from a tetracarboxylic acid and a specific diamine compound, and having an imidization rate of 30 mol% to 90 mol% (see claim 1). When this polyimide precursor is used to produce a polyimide film, the linear thermal expansion coefficient can be advantageously reduced without the need for a stretching operation that is often performed in the production of polyimide films. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2012 / 011590 [Patent Document 2] International Publication No. 2013 / 179727 [Patent Document 3] International Publication No. 2014 / 038715 [Patent Document 4] JP 2010-202729 A [Patent Document 5] International Publication No. 2018 / 221607 [Patent Document 6] International Publication No. 2015 / 080158 [Patent Document 7] International Publication No. 2014 / 208704 Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, the invention of Patent Document 7 makes it possible to produce a polyimide film having excellent properties. However, it is desirable to further improve various properties such as thermal properties, heat resistance, mechanical properties, and transparency in a well-balanced manner.

[0011] The present invention has been made in consideration of the problems of the prior art, and a main object of the present invention is to provide a polyimide precursor composition capable of producing a polyimide film having excellent thermal properties and / or heat resistance and also excellent transparency. Another object of the present invention is to provide a polyimide film and a polyimide film / substrate laminate obtained by using the polyimide precursor composition, and another object of the present invention is to provide a method for producing a flexible electronic device using the polyimide precursor composition, and a flexible electronic device. [Means for solving the problem]

[0012] The main disclosures of this application can be summarized as follows:

[0013] 1. A polyimide precursor comprising repeating units represented by the following general formula (I) and repeating units in which the general formula (I) is further imidized, the imidization rate being greater than 0% and less than 50%, and solvent A polyimide precursor composition comprising:

[0014] [ka] (In the general formula I, X1 is a tetravalent aliphatic group or aromatic group, Y1 is a divalent aliphatic group or aromatic group, R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, provided that 70 mol % or more of X1 is a group represented by the formula (1-1):

[0015] [ka] wherein 70 mol % or more of Y1 is represented by formula (D-1) and / or (D-2):

[0016] [ka] It is a structure represented by the following formula:

[0017] 2. The polyimide precursor composition according to item 1 above, wherein a polyimide film obtained from the polyimide precursor composition has a light transmittance of 79% or more at a wavelength of 400 nm when the film has a thickness of 10 μm.

[0018] 3. The polyimide precursor composition according to item 1 or 2 above, wherein a polyimide film obtained from the polyimide precursor composition has a linear thermal expansion coefficient of 20 ppm / K or less between 150°C and 250°C when the film has a thickness of 10 µm.

[0019] 4. The polyimide precursor composition according to any one of items 1 to 3 above, wherein a polyimide obtained from the polyimide precursor composition has a 5% weight loss temperature of 500° C. or higher.

[0020] 5. The polyimide precursor composition according to any one of items 1 to 4, wherein a polyimide film obtained from the polyimide precursor composition has a breaking elongation of 10% or more for a film having a thickness of 10 μm.

[0021] 6. The polyimide precursor composition according to any one of items 1 to 5, wherein 90 mol % or more of X1 are the structure represented by formula (1-1).

[0022] 7. A polyimide film obtained from the polyimide precursor composition according to any one of items 1 to 6 above.

[0023] 8. A polyimide film obtained from the polyimide precursor composition according to any one of items 1 to 6 above; Substrate and A polyimide film / substrate laminate comprising:

[0024] 9. The laminate according to item 8, wherein the base material is a glass substrate.

[0025] 10. (a) a step of applying the polyimide precursor composition according to any one of items 1 to 6 onto a substrate; and (b) a step of heat-treating the polyimide precursor on the substrate and laminating a polyimide film on the substrate; A method for producing a polyimide film / substrate laminate having the above structure.

[0026] 11. The method according to item 10, wherein the base material is a glass substrate.

[0027] 12. (a) A step of applying the polyimide precursor composition according to any one of items 1 to 6 onto a substrate; (b) heat-treating the polyimide precursor on the substrate to produce a polyimide film / substrate laminate in which a polyimide film is laminated on the substrate; (c) forming at least one layer selected from a conductive layer and a semiconductor layer on the polyimide film of the laminate; and (d) peeling the polyimide film from the substrate A method for producing a flexible electronic device comprising the steps of:

[0028] 13. The method according to item 12, wherein the base material is a glass substrate. Effect of the Invention

[0029] According to the present invention, it is possible to provide a polyimide precursor composition capable of producing a polyimide film having excellent thermal properties (such as a low linear thermal expansion coefficient) and / or heat resistance (such as a 5% weight loss temperature) and also excellent transparency. According to an embodiment of the polyimide precursor composition of the present invention, it is possible to produce a polyimide film having at least one of the thermal properties, such as (i) a low linear thermal expansion coefficient, and (ii) heat resistance, such as a 5% weight loss temperature, as well as excellent transparency.

[0030] According to another aspect of the present invention, there are provided a polyimide film and a polyimide film / substrate laminate obtained by using the polyimide precursor composition. According to another aspect of the present invention, there are provided a method for producing a flexible electronic device using the polyimide precursor composition, and a flexible electronic device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In this application, the term "flexible (electronic) device" means that the device itself is flexible, and the device is usually completed by forming a semiconductor layer (such as transistors and diodes as elements) on a substrate. The "flexible (electronic) device" is distinguished from devices such as COF (Chip On Film) in which a "hard" semiconductor element such as an IC chip is mounted on a conventional FPC (flexible printed circuit board). However, there is no problem in mounting a "hard" semiconductor element such as an IC chip on a flexible substrate or electrically connecting the same to the flexible substrate to operate or control the "flexible (electronic) device" of this application. Suitable flexible (electronic) devices include display devices such as liquid crystal displays, organic EL displays, and electronic paper, solar cells, and light-receiving devices such as CMOS.

[0032] The polyimide precursor composition of the present invention will be described below, followed by a description of a method for producing a flexible electronic device.

[0033] <<Polyimide precursor composition>> The polyimide precursor composition for forming the polyimide film contains a polyimide precursor and a solvent. The polyimide precursor is dissolved in the solvent.

[0034] The polyimide precursor contains a repeating unit represented by the following general formula (I) and a repeating unit in which the general formula (I) is further imidized.

[0035] [ka] (In general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, and R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

[0036] The repeating unit of general formula (I) which is further imidized is a structure in which one or two of the two amide bonds present in general formula (I) are converted to imide bonds, and specifically, the repeating unit of general formulae (Ib), (Ic), and (II) below:

[0037] [ka]

[0038] [ka]

[0039] [ka] As shown in the figure.

[0040] The imidization rate is the rate at which amide bonds in general formula (I) are converted to imide bonds. Therefore, when all repeating units in the polyimide precursor are of general formula (I), the imidization rate is 0%, when all repeating units are of general formula (Ib) and / or (Ic), the imidization rate is 50%, and when all repeating units are of general formula (II), the imidization rate is 100% (i.e., polyimide). In the present invention, an imidization rate of more than 0% and less than 50% means that in addition to the structure of general formula (I), at least one of general formulas (Ib), (Ic), and (II) is present so as to achieve a predetermined imidization rate.

[0041] The imidization rate is the polyimide precursor (solution) 1 It can be calculated by measuring the H-NMR spectrum and averaging the ratio of the integral value of the aromatic proton peak (7 to 8.3 ppm) to the integral value of the amide proton peak (9.5 to 10.5 ppm).

[0042] In addition, a polyimide precursor having an adjusted imidization rate can be produced by a production method including a step of reacting a tetracarboxylic acid component with a diamine component, or after obtaining a precursor having a repeating unit represented by general formula (I) from a tetracarboxylic acid component and a diamine component, for an appropriate time under appropriate conditions for the imidization reaction to proceed so as to achieve a desired imidization rate.

[0043] The details will be described later, but broadly speaking, there are a method in which the imidization reaction is caused to proceed evenly (or randomly) within the molecule (for simplicity, this is called a single-stage supply method), and a method in which the tetracarboxylic acid component and the diamine component are each divided and supplied, and the imidization reaction is caused to proceed only between a portion of the tetracarboxylic acid component and a portion of the diamine component (or in a block manner) (for simplicity, this is called a multi-stage supply method).

[0044] In the one-stage supply method, when the tetracarboxylic acid component and the diamine component react with each other, or after obtaining a precursor having a repeating unit represented by general formula (I) from the tetracarboxylic acid component and the diamine component, the reaction is carried out at an appropriate temperature for an appropriate time so that the imidization proceeds to a desired imidization rate. The temperature range is, for example, 0°C or higher, preferably 15°C or higher, and, for example, 180°C or lower, preferably 150°C or lower, more preferably 130°C or lower. The time range is generally such that the higher the temperature, the shorter the time required to adjust the imidization rate, and the lower the temperature, the longer the time required to adjust the imidization rate. However, it is preferable to appropriately select the time range, for example, from several seconds or more, for example, from 1 minute to about 1 year. In addition, it is preferable to change the reaction temperature and reaction time depending on the presence or absence of addition of an imidazole compound described later, and the type and amount of the compound. The one-stage supply method is preferably carried out by thermal imidization, and it is preferable not to include a dehydrating agent for chemical imidization.

[0045] In the two-stage supply method, the tetracarboxylic acid component and the diamine component are divided and supplied to a plurality of steps, and the imidization rate is adjusted by a method in which the reaction is carried out under different conditions in the plurality of steps. As an example, in the case of two-stage supply, only a portion of the tetracarboxylic acid component and a portion of the diamine component are supplied in the first step, and high-temperature heating is performed in which the imidization reaction proceeds rapidly. As a result, a precursor with complete imidization or a high imidization rate is obtained, and then in the second step, the remaining tetracarboxylic acid component and the diamine component are supplied and reacted under conditions in which the imidization reaction is suppressed. The high-temperature heating conditions in the first step are preferably 100°C or higher, more preferably 120°C to 250°C, and the temperature conditions in the second step are less than 100°C, more preferably less than 90°C. The temperature is usually 0°C or higher, preferably 15°C or higher. The imidization rate can be adjusted by the distribution ratio of the tetracarboxylic acid component and the diamine component in the first step and the second step. In this method, too, it is preferably performed by thermal imidization, and it is preferable that a dehydrating agent for chemical imidization is not included.

[0046] Since general formulae (Ib), (Ic) and (II) are repeating units in which the structure of general formula (I) is further imidized, X1, Y1, R1 and R2 in general formulae (Ib), (Ic) and (II) each have a group derived from general formula (I). Therefore, the following description of a preferred structure for general formula (I) also applies to the structures of general formulae (Ib), (Ic) and (II).

[0047] The precursor represented by the general formula (I) is particularly preferably a polyamic acid in which R1 and R2 are hydrogen atoms. When X1 and Y1 are aliphatic groups, the aliphatic groups are preferably groups having an alicyclic structure.

[0048] Of all the repeating units in the polyimide precursor, preferably 70 mol % or more of X1 is a structure represented by the following formula (1-1), i.e., a structure derived from norbornane-2-spiro-α-cyclopentanone-α'-spiro-2″-norbornane-5,5″,6,6″-tetracarboxylic dianhydride (hereinafter, abbreviated as CpODA as necessary).

[0049] [ka]

[0050] Of all the repeating units in the polyimide precursor, preferably 70 mol % or more of Y1 are structures represented by the following formulas (D-1) and / or (D-2), i.e., structures derived from 4,4'-diaminobenzanilide (abbreviated as DABAN if necessary).

[0051] [ka]

[0052] By using a composition containing such a polyimide precursor, it is possible to produce a polyimide film that has excellent thermal properties such as a low linear thermal expansion coefficient and also has excellent transparency.

[0053] The polyimide precursor will be explained with reference to the monomers (tetracarboxylic acid component, diamine component, other components) that provide X1 and Y1 in the general formula (I), and then the production method will be explained.

[0054] In this specification, the tetracarboxylic acid component includes tetracarboxylic acid, tetracarboxylic dianhydride, and other tetracarboxylic acid derivatives such as tetracarboxylic acid silyl ester, tetracarboxylic acid ester, and tetracarboxylic acid chloride, which are used as raw materials for producing polyimide. Although not particularly limited, it is convenient to use tetracarboxylic dianhydride in production, and the following description will be given of an example in which tetracarboxylic dianhydride is used as the tetracarboxylic acid component. In addition, the diamine component is a diamine compound having two amino groups (-NH2) that is used as a raw material for producing polyimide.

[0055] In addition, in this specification, the polyimide film means both the one formed on a (carrier) substrate and present in the laminate, and the film after peeling off the substrate. Also, the material constituting the polyimide film, that is, the material obtained by heat-treating (imidizing) the polyimide precursor composition, may be referred to as the "polyimide material".

[0056] <X1 and tetracarboxylic acid component> As described above, among all the repeating units in the polyimide precursor, X1 preferably has a structure represented by the formula (1-1) in an amount of 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and most preferably 95 mol% or more (100 mol% is also very preferable), and has a structure represented by the formula (1-1). The tetracarboxylic dianhydride that gives the structure of the formula (1-1) as X1 is CpODA.

[0057] CpODA may be a mixture of stereoisomers or a specific stereoisomer. Although not particularly limited, preferable stereoisomers include trans-endo-endo-norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic dianhydride (CpODA-tee) and cis-endo-endo-norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic dianhydride (CpODA-cee).

[0058] [Chemical formula]

[0059] In a preferred embodiment, at least 50 mol % or more, and even more preferably 63 mol % or more of CpODA-tee is present in CpODA. In a different preferred embodiment, at least 30 mol % or more, and even more preferably 37 mol % or more of CpODA-cee is present in CpODA. In a further different preferred embodiment, the sum of CpODA-tee and CpODA-cee is at least 80 mol % or more, and even more preferably 83 mol % or more of CpODA.

[0060] In the present invention, X1 may contain a tetravalent aliphatic group or aromatic group other than the structure represented by formula (1-1) (abbreviated as "other X1") in an amount that does not impair the effects of the present invention. That is, the tetracarboxylic acid component may contain other tetracarboxylic acid derivatives in addition to CpODA in an amount that does not impair the effects of the present invention. The amount of other tetracarboxylic acid derivatives is less than 30 mol%, more preferably less than 20 mol%, and even more preferably less than 10 mol% (0 mol% is also preferable) relative to 100 mol% of the tetracarboxylic acid component.

[0061] When "another X1" is a tetravalent group having an aromatic ring, it is preferably a tetravalent group having an aromatic ring having 6 to 40 carbon atoms.

[0062] Examples of the tetravalent group having an aromatic ring include the following.

[0063] [ka] (In the formula, Z1 is a direct bond or the following divalent group:

[0064] [ka] In the formula, Z2 is a divalent organic group, Z 3、 Z4 is independently an amide bond, an ester bond, or a carbonyl bond, and Z5 is an organic group containing an aromatic ring.

[0065] Specific examples of Z2 include aliphatic hydrocarbon groups having 2 to 24 carbon atoms and aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0066] Specific examples of Z5 include aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0067] As the tetravalent group having an aromatic ring, the following are particularly preferred since they can provide a polyimide film having both high heat resistance and high transparency.

[0068] [ka] (In the formula, Z1 is a direct bond or a hexafluoroisopropylidene bond.)

[0069] Here, Z1 is more preferably a direct bond, since this allows the resulting polyimide film to have high heat resistance, high transparency, and a low linear thermal expansion coefficient all at the same time.

[0070] In addition, as a preferred group, in the above formula (9), Z1 is the following formula (3A):

[0071] [ka] Examples of such compounds include compounds having a fluorenyl-containing group represented by the formula: 11 and Z 12 are each independently, preferably the same, a single bond or a divalent organic group. 11 and Z 12 As the group, an organic group containing an aromatic ring is preferable, for example, a group represented by the formula (3A1):

[0072] [ka] (Z 13 and Z 14 are each independently a single bond, -COO-, -OCO- or -O-, where Z 14 When attached to a fluorenyl group, Z13 is -COO-, -OCO- or -O- and Z 14 is preferably a single bond; R 91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably methyl, and n is an integer of 0 to 4, preferably 1. The structure represented by the following formula is preferred.

[0073] Examples of tetracarboxylic acid components that provide repeating units of general formula (I) in which X1 is a tetravalent group having an aromatic ring include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, pyromellitic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, and the like. Examples of the tetracarboxylic acid component that provides the repeating unit of general formula (I) in which X1 is a tetravalent group having an aromatic ring containing a fluorine atom include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane and its derivatives such as tetracarboxylic acid dianhydride, tetracarboxylic acid silyl ester, tetracarboxylic acid ester, and tetracarboxylic acid chloride. Further, 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 component may be used alone or in combination of two or more kinds.

[0074] When "other X1" is a tetravalent group having an alicyclic structure, it is preferably a tetravalent group having an alicyclic structure having 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. Preferable tetravalent groups having an aliphatic 4-membered ring or an aliphatic 6-membered ring include the following.

[0075] [ka] (In the formula, R 31 ~R 38 R is independently a direct bond or a divalent organic group. 41 ~R 47 , and R 71 ~R 73 R each independently represents one selected from the group consisting of groups represented by the formulas: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-. 48 is an organic group containing an aromatic ring or an alicyclic structure.

[0076] R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 , R 38 Specific examples of the bond include a direct bond, an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an oxygen atom (-O-), a sulfur atom (-S-), a carbonyl bond, an ester bond, and an amide bond.

[0077] R 48 Examples of the organic group containing an aromatic ring include the following.

[0078] [ka] (Wherein, W1 is a direct bond or a divalent organic group, n 11 ~n 13 each independently represents an integer of 0 to 4; R 51 , R 52 , R53 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.

[0079] 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).

[0080] [ka] (R in Equation (6) 61 ~R 68 each independently represents a direct bond or a divalent group represented by the formula (5).

[0081] As the tetravalent group having an alicyclic structure, the following are particularly preferred since they can provide the resulting polyimide with high heat resistance, high transparency, and a low linear thermal expansion coefficient.

[0082] [ka]

[0083] Examples of tetracarboxylic acid components which provide the repeating unit of formula (I) in which X1 is a tetravalent group having an alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic acid, isopropylidenediphenoxybisphthalic acid, cyclohexane-1,2,4,5-tetracarboxylic acid, [1,1'-bi(cyclohexane)]-3,3',4,4'-tetracarboxylic acid, [1,1'-bi(cyclohexane)]-2,3,3',4'-tetracarboxylic acid, [1,1'-bi(cyclohexane)]-2,2',3,3'-tetracarboxylic acid, 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic acid), 4,4'-thiobis(cyclohexane-1,2-dicarboxylic acid), 4,4'-sulfonylbis( cyclohexane-1,2-dicarboxylic acid), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), octahydropentalene-1,3,4,6-tetracarboxylic acid, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid, 6-(carboxymethyl)bicyclo[2. 2.1]heptane-2,3,5-tricarboxylic acid, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2.2.2]oct-5-ene-2,3,7,8-tetracarboxylic acid, tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid, tricyclo[4.2.2.02,5]dec-7-ene-3,4,9,10-tetracarboxylic acid, 9-oxatricyclo[4.2.1.02,5]Nonane-3,4,7,8-tetracarboxylic acid, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic acid, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic acid, decahydro-1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, and derivatives thereof such as tetracarboxylic dianhydrides, tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides. The tetracarboxylic acid component may be used alone or in combination of two or more kinds.

[0084] <Y1 and diamine component> As described above, in all repeating units in the polyimide precursor, Y1 preferably has a structure represented by the formula (D-1) and / or (D-2) in an amount of 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more (100 mol% is also preferable), and is a structure represented by the formula (D-1) and / or (D-2). The diamine compound that gives the structure of the formula (D-1) and the formula (D-2) as Y1 is 4,4'-diaminobenzanilide (abbreviation: DABAN).

[0085] In the present invention, as Y1, a divalent aliphatic group or aromatic group other than the structures represented by the formulas (D-1) and (D-2) (abbreviated as "other Y1") can be contained in an amount that does not impair the effects of the present invention. That is, the diamine component can contain other diamine compounds in an amount that does not impair the effects of the present invention in addition to DABAN. The amount of the other diamine compound is less than 30 mol%, more preferably less than 20 mol%, still more preferably less than 10 mol% (0 mol% is also preferable) based on 100 mol% of the diamine component.

[0086] When "other Y1" is a divalent group having an aromatic ring, it is preferably a divalent group having an aromatic ring having 6 to 40 carbon atoms, more preferably 6 to 20 carbon atoms.

[0087] Examples of the divalent group having an aromatic ring include the following.

[0088] [ka] (Wherein, W1 is a direct bond or a divalent organic group, n 11 ~n 13 each independently represents an integer of 0 to 4; 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.

[0089] 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).

[0090] [ka]

[0091] [ka] (R in Equation (6) 61 ~R 68 each independently represents a direct bond or a divalent group represented by the formula (5).

[0092] Here, it is particularly preferable that W1 is a direct bond or one selected from the group consisting of groups represented by the formulae: -NHCO-, -CONH-, -COO-, and -OCO-, because the resulting polyimide can have high heat resistance, high transparency, and a low linear thermal expansion coefficient at the same time. 61 ~R 68is particularly preferably any one of a direct bond or a divalent group represented by the formula (6), which is one selected from the group consisting of groups represented by the formulas: -NHCO-, -CONH-, -COO-, and -OCO-. However, when -NHCO- or -CONH- is selected, "other Y1" is selected so as to be different from formula (D-1) or formula (D-2).

[0093] In addition, as a preferred group, in the above formula (4), W1 is the following formula (3B):

[0094] [ka] Examples of such compounds include compounds having a fluorenyl-containing group represented by the formula: 11 and Z 12 are each independently, preferably the same, a single bond or a divalent organic group. 11 and Z 12 As the group, an organic group containing an aromatic ring is preferable, for example, a group represented by the formula (3B1):

[0095] [ka] (Z 13 and Z 14 are each independently a single bond, -COO-, -OCO- or -O-, where Z 14 When attached to a fluorenyl group, Z 13 is -COO-, -OCO- or -O- and Z 14 is preferably a single bond; R 91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably phenyl, and n is an integer of 0 to 4, preferably 1. The structure represented by the following formula is preferred.

[0096] Another preferred group is a compound represented by the above formula (4) in which W1 is a phenylene group, that is, a terphenyldiamine compound, and particularly preferred is a compound in which all bonds are para-bonded.

[0097] As another preferred group, in the above formula (4), W1 is R 61 and R 62 is a 2,2-propylidene group.

[0098] As yet another preferred group, in the above formula (4), W1 is represented by the following formula (3B2):

[0099] [ka] Examples of the compound include compounds represented by the following formula:

[0100] Examples of diamine components that provide repeating units of general formula (I) in which Y1 is a divalent group having an aromatic ring include p-phenylenediamine, m-phenylenediamine, benzidine, 3,3'-diamino-biphenyl, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, m-tolidine, 3,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)terephthalamide, N,N'-p-phenylenebis(p-aminobenzamide), and 4-aminophenoxy-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-aminophenoxy)benzene, 1, 3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 3,3'-bis(trifluoromethyl)benzidine, 3,3'-bis((aminophenoxy)phenyl)propane, 2,2'-bis(3-amino-4 -hydroxyphenyl)hexafluoropropane, bis(4-(4-aminophenoxy)diphenyl)sulfone, bis(4-(3-aminophenoxy)diphenyl)sulfone, octafluorobenzidine, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-triazine, 2,Examples of the diamine component that provides the repeating unit of the general formula (I) in which Y1 is a divalent group having an aromatic ring containing a fluorine atom include 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, and 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. Additionally, preferred diamine compounds include 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1"-terphenyl]-4,4"-diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine. The diamine components may be used alone or in combination.

[0101] When "other Y1" is a divalent group having an alicyclic structure, it is preferably a divalent group having an alicyclic structure having 4 to 40 carbon atoms, and further preferably has at least one aliphatic 4- to 12-membered ring, more preferably aliphatic 6-membered ring.

[0102] Examples of the divalent group having an alicyclic structure include the following.

[0103] [ka] (In the formula, V1 and V2 each independently represent a direct bond or a divalent organic group, n 21 ~n 26 each independently represents an integer of 0 to 4; R 81 ~R 86 are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group, and R91 , R 92 , R 93 are each independently one selected from the group consisting of groups represented by the formula: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-.

[0104] Specific examples of V1 and V2 include a direct bond and a divalent group represented by the above formula (5).

[0105] As the divalent group having an alicyclic structure, the following are particularly preferred since they can provide a polyimide having both high heat resistance and a low linear thermal expansion coefficient.

[0106] [ka] Among the divalent groups having an alicyclic structure, the following are preferred:

[0107] [ka]

[0108] Examples of diamine components that provide repeating units of general formula (I) in which Y1 is a divalent group having an alicyclic structure include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclobutane, 1, Examples of the diamine component include 4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, diaminobicycloheptane, diaminomethylbicycloheptane, diaminooxybicycloheptane, diaminomethyloxybicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane. The diamine component may be used alone or in combination of multiple types.

[0109] As the tetracarboxylic acid component and diamine component that give the repeating unit represented by the general formula (I), any of aliphatic tetracarboxylic acids other than alicyclic (particularly dianhydrides) and / or aliphatic diamines can be used, and the content thereof is preferably less than 30 mol%, more preferably less than 20 mol%, and even more preferably less than 10 mol% (including 0%) relative to 100 mol% in total of the tetracarboxylic acid component and the diamine component.

[0110] The transparency of the resulting polyimide film may be improved by including a structure represented by formula (4) and a diamine compound such as p-phenylenediamine, 3,3'-bis(trifluoromethyl)benzidine, m-tolidine, or 4,4'-bis(4-aminophenoxy)biphenyl as "other Y1". The transparency of the resulting polyimide film may be improved by including a structure represented by formula (3B) and a diamine compound such as 9,9-bis(4-aminophenyl)fluorene as "other Y1". The Tg may be improved and the retardation in the film thickness direction may be reduced by including a structure represented by formula (3B) and a diamine compound such as 9,9-bis(4-aminophenyl)fluorene as "other Y1".

[0111] The polyimide precursor can be produced from the above tetracarboxylic acid component and diamine component. The polyimide precursor used in the present invention (a polyimide precursor containing at least one repeating unit represented by the above formula (I)) can be produced according to the chemical structures of R1 and R2. 1) Polyamic acid (R1 and R2 are hydrogen; also known as polyamic acid), 2) Polyamic acid ester (at least a part of R1 and R2 is an alkyl group; also known as polyamic acid ester), 3) 4) Polyamic acid silyl ester (at least a part of R1 and R2 is an alkylsilyl group; also known as polyamic acid silyl ester), The polyimide precursors can be easily produced according to the following production methods for each of the above categories. However, the production methods for the polyimide precursors used in the present invention are not limited to the following production methods.

[0112] 1) Polyamic acid When the repeating unit represented by formula (I) is a polyamic acid, either a single-stage supply method in which the imidization reaction proceeds evenly (or randomly) within the molecule or a multi-stage supply method in which the tetracarboxylic acid component and the diamine component are each divided and supplied, and the imidization reaction proceeds only between a portion of the tetracarboxylic acid component and a portion of the diamine component (or in a block manner) can be used.

[0113] An example of the production of a polyimide precursor by the one-stage supply method will be described. In a solvent, tetracarboxylic dianhydride and diamine components as tetracarboxylic acid components are reacted in approximately equal moles, preferably with a molar ratio of the diamine component to the tetracarboxylic acid component [moles of diamine component / moles of tetracarboxylic acid component] of 0.90 to 1.10, more preferably 0.95 to 1.05, at a relatively low temperature of, for example, 120°C or less while suppressing excessive imidization. Although not limited, more specifically, diamine is dissolved in an organic solvent or water, and tetracarboxylic dianhydride is gradually added to this solution while stirring, and stirred at a temperature of 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours. After that, if necessary, the imidization rate may be adjusted by storing the mixture at, for example, 5°C to 40°C for a predetermined time, for example, for about 1 day to 1 year, to further promote imidization. The order of addition of diamine and tetracarboxylic dianhydride is preferable because it is easy to increase the molecular weight of the polyimide precursor. It is also possible to reverse the order of addition of the diamine and the tetracarboxylic dianhydride in the above-mentioned production method, which is preferable since the amount of precipitates is reduced. When water is used as a solvent, it is preferable to add an imidazole such as 1,2-dimethylimidazole or a base such as triethylamine, preferably in an amount of 0.8 times or more equivalent to the carboxyl group of the polyamic acid (polyimide precursor) to be produced. When the reaction between the tetracarboxylic acid component and the diamine component is carried out at a relatively high temperature, for example, 80° C. or higher, 90° C. or higher, or 100° C. or higher, it is possible to achieve a target imidization rate in a relatively short period of time while suppressing excessive imidization reaction, and therefore the resulting product can be used as is as the "polyimide precursor composition of the present invention."

[0114] On the other hand, the temperature (heating) step (stage) of the reaction can be divided into two steps. In one embodiment, the reaction of the tetracarboxylic acid component and the diamine component is carried out at a relatively low temperature (for example, 0° C. or higher and 80° C. or lower, or even 70° C. or lower) in the first step to obtain a polyimide precursor with a low imidization rate (including 0% imidization rate), and then in the second step, the reaction is heated at a relatively high temperature, for example, 80° C. or higher, preferably 90° C. or higher, and more preferably 100° C. or higher, for example, for 5 minutes to 72 hours to suppress excessive imidization reaction and achieve a target imidization rate. In another embodiment, the reaction of the tetracarboxylic acid component and the diamine component is carried out at a relatively low temperature (for example, 0° C. or higher and 80° C. or lower, or even 70° C. or lower) in the first step to obtain a polyimide precursor with a low imidization rate (including 0% imidization rate), and then in the second step, the imidization is carried out at a relatively low temperature, for example, 0° C. or higher and 80° C. or lower (or less), preferably 70° C. or lower, for a predetermined time, for example, about one day to one year, to adjust the imidization rate. Dividing the reaction temperature (heating) step into two steps is advantageous in that a stable polymerization reaction can be achieved by carrying out the reaction of the tetracarboxylic acid component and the diamine component at a relatively low temperature in the first step.

[0115] Next, an example of the production of a polyimide precursor by the multi-stage supply method will be described, taking two-stage supply as an example. First, in the first step, under conditions in which the imidization reaction proceeds, specifically at a temperature of, for example, 100°C or higher, a tetracarboxylic dianhydride as a tetracarboxylic acid component is reacted with a diamine component. More specifically, a diamine is dissolved in a solvent, and while stirring the solution, a tetracarboxylic dianhydride is gradually added, and the mixture is stirred at 100°C or higher, preferably in the range of 120 to 250°C, for 0.5 to 72 hours, to obtain a soluble imide compound. The order of addition of the diamine and the tetracarboxylic dianhydride may be reversed.

[0116] The degree of polymerization of the imide compound can be determined by the molar ratio of the tetracarboxylic acid component and the diamine component to be reacted so that the imide compound is soluble. Both ends of the soluble imide compound may be acid anhydride groups, carboxyl groups, or amino groups.

[0117] The imidization is carried out by thermal imidization, and therefore does not involve the use of chemical imidization agents, which are acid anhydrides (dehydrating agents) such as acetic anhydride, and amine compounds (catalysts) such as pyridine and isoquinoline.

[0118] Next, in the second step, a tetracarboxylic acid component and / or a diamine component are added to the reaction solution containing the soluble imide compound obtained in the first step to carry out a reaction, thereby obtaining a polyimide precursor of the present invention. In this second step, the tetracarboxylic acid component and / or the diamine component are added so that the molar ratio of the total amount of the tetracarboxylic acid component to the total amount of the diamine component reacted in the first and second steps is approximately equimolar, preferably such that the molar ratio of the diamine component to the tetracarboxylic acid component [moles of the diamine component / moles of the tetracarboxylic acid component] is 0.90 to 1.10, more preferably 0.95 to 1.05.

[0119] In the second step, the reaction is carried out under conditions that suppress imidization, specifically at a temperature of less than 100°C. More specifically, a diamine is added to the reaction solution containing the soluble imide compound obtained in the first step, and the mixture is stirred at a temperature of less than 100°C, preferably in the range of -20 to 80°C, for 1 to 72 hours, and then a tetracarboxylic dianhydride is added and the mixture is stirred at a temperature of less than 100°C, preferably in the range of -20 to 80°C, for 1 to 72 hours, to obtain the polyimide precursor of the present invention. The order of addition of the diamine and the tetracarboxylic dianhydride may be reversed, or the diamine and the tetracarboxylic dianhydride may be added simultaneously. In addition, when the entire amount of the tetracarboxylic acid component to be reacted is added to the solvent in the first step, only the diamine is added, and when the entire amount of the diamine component to be reacted is added to the solvent in the first step, only the tetracarboxylic dianhydride is added.

[0120] Although imidization may proceed in the second step, the reaction temperature and reaction time are appropriately selected so that the imidization rate of the finally obtained polyimide precursor falls within a predetermined range. In this way, the imidization rate can be adjusted by producing mainly repeating units of the imide structure (structure of general formula (II)) in the first step and mainly repeating units of the amic acid structure represented by the chemical formula (I) in the second step.

[0121] 2) Polyamic acid ester The repeating unit represented by formula (I) can be obtained by the following reaction. First, tetracarboxylic dianhydride is reacted with any alcohol to obtain a diester dicarboxylic acid, which is then reacted with a chlorinating agent (thionyl chloride, oxalyl chloride, etc.) to obtain a diester dicarboxylic acid chloride. This diester dicarboxylic acid chloride and diamine are stirred at -20 to 120°C, preferably at -5 to 80°C, for 1 to 72 hours to obtain a polyimide precursor (polyamic acid ester). When reacting at 80°C or higher, the molecular weight varies depending on the temperature history during polymerization, and imidization progresses due to heat, so that it may not be possible to stably produce the polyimide precursor. In addition, a polyimide precursor can be easily obtained by dehydrating and condensing a diester dicarboxylic acid and a diamine using a phosphorus-based condensing agent, a carbodiimide condensing agent, or the like.

[0122] The polyimide precursor obtained by this method is stable, and therefore can be purified by reprecipitation or other methods by adding a solvent such as water or alcohol.

[0123] The obtained polyimide precursor (polyamic acid ester) can be reacted in the same manner as in 1) polyamic acid (see the second stage in the one-stage supply method, i.e., first stage low temperature-second stage high temperature and first stage low temperature-second stage low temperature). That is, in one embodiment, the imidization is performed at a relatively high temperature, for example, 80° C. or higher, preferably 90° C. or higher, and more preferably 100° C. or higher, for example, 5 minutes to 72 hours to achieve a desired imidization rate while suppressing excessive imidization reaction. In another embodiment, the imidization rate can be adjusted by proceeding with imidization at a relatively low temperature, for example, 0° C. or higher and 80° C. or lower (or lower), preferably 70° C. or lower, for a predetermined time, for example, about one day to one year.

[0124] 3) Polyamic acid silyl ester (indirect method) The repeating unit represented by formula (I) is a polyamic acid silyl ester, which can be obtained by the reaction of the indirect method described in this section or the direct method described in the next section. In the indirect method, a diamine is reacted with a silylating agent in advance to obtain a silylated diamine. If necessary, the silylated diamine is purified by distillation or the like. The silylated diamine is dissolved in a dehydrated solvent, and a tetracarboxylic dianhydride is gradually added while stirring. The mixture is stirred at 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours to obtain a polyimide precursor. When the reaction is performed at 80°C or higher, the molecular weight varies depending on the temperature history during polymerization, and imidization proceeds due to heat, so that the polyimide precursor may not be stably produced.

[0125] The obtained polyimide precursor (polyamic acid silyl ester) can be reacted in the same manner as in 1) polyamic acid (see the second stage in the one-stage supply method, i.e., first stage low temperature-second stage high temperature and first stage low temperature-second stage low temperature). That is, in one embodiment, the imidization is performed at a relatively high temperature, for example, 80° C. or higher, preferably 90° C. or higher, and more preferably 100° C. or higher, for example, for 5 minutes to 72 hours to achieve a desired imidization rate while suppressing excessive imidization reaction. In another embodiment, the imidization rate can be adjusted by proceeding with imidization at a relatively low temperature, for example, 0° C. or higher and 80° C. or lower (or lower), preferably 70° C. or lower, for a predetermined time, for example, about one day to one year.

[0126] 4) Polyamic acid silyl ester (direct method) The polyamic acid solution having a predetermined imidization rate obtained by method 1) is mixed with a silylating agent and stirred at a temperature in the range of 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours to obtain a polyamic acid silyl ester having a predetermined imidization rate.

[0127] Alternatively, a tetracarboxylic dianhydride as a tetracarboxylic acid component and a diamine component are reacted under conditions that suppress imidization, for example at a temperature of less than 100°C, to obtain a polyamic acid with a low imidization rate (see the first step in the case of dividing the heating step into two steps in the one-stage supply method in the above section 1) Polyamic acid). A silylating agent is mixed into the obtained polyamic acid solution, and the mixture is stirred at 0 to 120°C, preferably 5 to 80°C, for 1 to 72 hours to obtain a polyamic acid silyl ester with a low imidization rate. The obtained polyimide precursor (polyamic acid silyl ester) can be reacted in the same manner as in the above 3) Polyamic acid silyl ester (indirect method) to achieve a desired imidization rate.

[0128] In the methods 3) and 4), it is preferable to use a silylating agent that does not contain chlorine, since there is no need to purify the silylated polyamic acid or the resulting polyimide. Examples of silylating agents that do not contain chlorine atoms include N,O-bis(trimethylsilyl)trifluoroacetamide, N,O-bis(trimethylsilyl)acetamide, and hexamethyldisilazane. N,O-bis(trimethylsilyl)acetamide and hexamethyldisilazane are particularly preferred because they do not contain fluorine atoms and are low cost.

[0129] In the silylation reaction of the diamine in method 3), an amine catalyst such as pyridine, piperidine, or triethylamine can be used to accelerate the reaction. This catalyst can be used as it is as a polymerization catalyst for the polyimide precursor.

[0130] The solvent used in preparing the polyimide precursor is preferably water or an aprotic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, or dimethyl sulfoxide, and is not particularly limited in structure since any type of solvent can be used without problems as long as it dissolves the raw material monomer components and the resulting polyimide precursor. As the solvent, water, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and N-ethyl-2-pyrrolidone, cyclic ester solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, and α-methyl-γ-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, and dimethyl sulfoxide are preferably used. In addition, other common organic solvents, such 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, turpentine, mineral spirits, petroleum naphtha solvents, etc., can also be used. A combination of multiple solvents can also be used.

[0131] In the production of the polyimide precursor, although there are no particular limitations, the monomer and the solvent are charged at a concentration such that the solids concentration of the polyimide precursor (polyimide equivalent mass concentration) is, for example, 5 to 45 mass % and the reaction is carried out.

[0132] The logarithmic viscosity of the polyimide precursor is not particularly limited, but it is preferable that the logarithmic viscosity in an N,N-dimethylacetamide solution having a concentration of 0.5 g / dL at 30° C. is 0.2 dL / g or more, more preferably 0.3 dL / g or more, and particularly preferably 0.4 dL / g or more. When the logarithmic viscosity is 0.2 dL / g or more, the molecular weight of the polyimide precursor is high, and the mechanical strength and heat resistance of the obtained polyimide are excellent.

[0133] <Preferred additives> The polyimide precursor composition may contain an imidazole compound. The addition of an imidazole compound may be effective in improving light transmittance and / or reducing the linear thermal expansion coefficient, but may also tend to increase the imidization rate depending on the compound selected. Therefore, when an imidazole compound is added, it is preferable to appropriately select the compound and / or appropriately adjust the imidization rate.

[0134] The imidazole compound is not particularly limited, but includes 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, benzimidazole, etc. From the viewpoint of the stability of the polyimide precursor composition, it is preferable to use at least one imidazole compound selected from 2-phenylimidazole and benzimidazole.

[0135] The content of the imidazole compound in the polyimide precursor composition can be appropriately selected in consideration of the balance between the effect of addition and the stability of the polyimide precursor composition. The amount of the imidazole compound is preferably more than 0.01 mol to less than 1 mol per mol of the repeating unit of the polyimide precursor. The addition of the imidazole compound generally improves mechanical properties such as elongation at break. On the other hand, if the content of the imidazole compound is too high, the storage stability of the polyimide precursor composition may be deteriorated.

[0136] The content of the imidazole compound is more preferably 0.02 mol or more, even more preferably 0.025 mol or more, even more preferably 0.05 mol or more, and more preferably 0.8 mol or less, even more preferably 0.6 mol or less, even more preferably 0.4 mol or less, even more preferably less than 0.4 mol, and most preferably 0.3 mol or less, relative to 1 mol of the repeating unit.

[0137] Incidentally, Patent Document 6 (International Publication No. 2015 / 080158) describes a polyimide precursor composition containing an imidazole compound, but there is no disclosure that a polyimide precursor composition containing 2-phenylimidazole and / or benzimidazole has excellent storage stability. In addition, the examples in the same document show that the 400 nm light transmittance of a polyimide film produced from a composition containing 2-phenylimidazole or benzimidazole is lower than that of 1,2-dimethylimidazole, 1-methylimidazole, and 2-methylimidazole. On the other hand, a polyimide film produced from a composition in which a preferred polyimide precursor of the present invention (70 mol% or more of X1 is derived from CpODA, and 70 mol% or more of Y1 is derived from DABAN) is combined with 2-phenylimidazole and / or benzimidazole has improved transparency, and contrary to the disclosure in Patent Document 6, a 400 nm light transmittance equal to or higher than that of 2-methylimidazole was obtained. It was also confirmed that 2-phenylimidazole and benzimidazole are more effective in reducing the linear thermal expansion coefficient than other imidazoles.

[0138] <Formulation of polyimide precursor composition> The polyimide precursor composition used in the present invention contains at least one polyimide precursor and a solvent, and may optionally further contain at least one of the above-mentioned imidazole compounds.

[0139] As the solvent, the above-mentioned solvents described as the solvent used when preparing the polyimide precursor can be used. Usually, the solvent used when preparing the polyimide precursor can be used as it is, that is, as the polyimide precursor solution, but it may be used after dilution or concentration as necessary. The imidazole compound is dissolved and exists in the polyimide precursor composition. The concentration of the polyimide precursor is not particularly limited, but is usually 5 to 45 mass% in terms of polyimide equivalent mass concentration (solid content concentration). Here, the polyimide equivalent mass is the mass when all the repeating units are completely imidized.

[0140] The viscosity (rotational viscosity) of the polyimide precursor of the present invention is not particularly limited, but is measured by using an E-type rotational viscometer at a temperature of 25° C. and a shear rate of 20 sec -1 The rotational viscosity measured by is preferably 0.01 to 1000 Pa·sec, more preferably 0.1 to 100 Pa·sec. Thixotropy can also be imparted as necessary. With a viscosity in the above range, the composition is easy to handle when coating or forming a film, and repellency is suppressed, resulting in excellent leveling properties, making it possible to obtain a good coating film.

[0141] The polyimide precursor composition of the present invention may contain, as necessary, antioxidants, ultraviolet absorbers, fillers (inorganic particles such as silica, etc.), dyes, pigments, coupling agents such as silane coupling agents, primers, flame retardants, defoamers, leveling agents, rheology control agents (flow aids), etc. It is preferable that the polyimide precursor composition of the present invention does not contain a chemical imidization agent.

[0142] In addition, the inventors' research has confirmed that the use of a polyimide precursor composition containing a specific siloxane compound reduces warpage of the produced polyimide film / glass substrate laminate. In the present invention, the polyimide precursor composition can contain an appropriate amount of a siloxane compound that does not impair transparency, or can contain no siloxane compound at all.

[0143] The polyimide precursor composition can be prepared by adding an imidazole compound or a solution of an imidazole compound to the polyimide precursor solution obtained by the above-mentioned method and mixing them. The tetracarboxylic acid component and the diamine component may be reacted in the presence of the imidazole compound.

[0144] <<Uses of polyimide precursor composition and film properties>> By further imidizing the polyimide precursor of the present invention, a polyimide can be produced. In the present invention, there is no particular limitation, and any known imidization method can be suitably applied. The form of the obtained polyimide can be suitably exemplified as a film, a laminate of a polyimide film and another substrate, a coating film, a powder, beads, a molded body, a foam, etc.

[0145] Although it depends on the application, the thickness of the polyimide film is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 5 μm or more, and for example, 250 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[0146] In one embodiment of the present invention, the polyimide film has a 400 nm light transmittance of preferably 79% or more, more preferably 80% or more, when measured on a 10 μm thick film, and a yellowness index (YI) of preferably 3.2 or less, more preferably 3.0 or less, most preferably 2.7 or less, when measured on a 10 μm thick film.

[0147] The polyimide film of the present invention has an extremely low coefficient of linear thermal expansion. In one embodiment of the present invention, the coefficient of linear thermal expansion (CTE) of the polyimide film from 150° C. to 250° C., measured on a film having a thickness of 10 μm, is preferably 20 ppm / K or less, more preferably less than 20 ppm, and most preferably 15 ppm / K or less, from 150° C. to 250° C.

[0148] The polyimide film of the present invention has extremely high heat resistance. In one embodiment of the present invention, the 5% weight loss temperature of the polyimide is preferably 500°C or higher, more preferably 505°C or higher, and even more preferably 510°C or higher. When forming a gas barrier film or the like on the polyimide to form a transistor on the polyimide, if the heat resistance is low, swelling may occur between the polyimide and the barrier film due to outgassing caused by decomposition of the polyimide. Generally, high heat resistance is preferable, but depending on the application, characteristics other than heat resistance are required, and the 5% weight loss temperature may be 500°C or lower.

[0149] Furthermore, in one embodiment of the present invention, the polyimide film preferably has a breaking elongation of 10% or more when the film has a thickness of 10 μm.

[0150] In another preferred embodiment of the present invention, the breaking strength of the polyimide film is preferably 150 MPa or more, more preferably 170 MPa or more, even more preferably 180 MPa or more, even more preferably 200 MPa or more, and even more preferably 210 MPa or more. The breaking strength may be, for example, a value obtained from a film having a thickness of about 5 to 100 μm.

[0151] It is particularly preferable that the polyimide film has the above-mentioned preferable properties simultaneously.

[0152] The polyimide film can be produced by a known method. A typical method is to cast a polyimide precursor composition onto a substrate, and then heat imidize the composition on the substrate to obtain a polyimide film. This method will be described later in relation to the production of a polyimide film / substrate laminate. Alternatively, the polyimide precursor composition can be cast onto a substrate, heated and dried to produce a self-supporting film, and then the self-supporting film can be peeled off from the substrate, and the film can be held, for example, by a tenter and heat imidized in a state in which degassing is possible from both sides of the film to obtain a polyimide film.

[0153] <<Manufacturing of polyimide film / substrate laminates and flexible electronic devices>> The polyimide film / substrate laminate of the present invention can be produced by (a) applying a polyimide precursor composition onto a substrate, and (b) heat-treating the polyimide precursor on the substrate to produce a laminate (polyimide film / substrate laminate) in which a polyimide film is laminated on the substrate. The method for producing a flexible electronic device of the present invention uses the polyimide film / substrate laminate produced in the steps (a) and (b) and includes further steps, namely (c) forming at least one layer selected from a conductive layer and a semiconductor layer on the polyimide film of the laminate, and (d) peeling the substrate from the polyimide film.

[0154] The polyimide precursor composition that can be used in the method of the present invention contains a polyimide precursor and a solvent. The polyimide precursor can be one described in the section on polyimide precursor composition. The polyimide precursor described as being preferred in the section on polyimide precursor composition is also preferred in the method of the present invention, but is not particularly limited thereto.

[0155] First, in step (a), a polyimide precursor composition is cast onto a substrate, and a polyimide film is formed by imidization and removal of the solvent through a heat treatment, thereby obtaining a laminate of the substrate and the polyimide film (polyimide film / substrate laminate).

[0156] As the substrate, a heat-resistant material is used, for example, a plate- or sheet-shaped substrate such as a ceramic material (glass, alumina, etc.), a metal material (iron, stainless steel, copper, aluminum, etc.), a semiconductor material (silicon, compound semiconductor, etc.), or a film- or sheet-shaped substrate such as a heat-resistant plastic material (polyimide, etc.). In general, a flat and smooth plate-shaped substrate is preferred, and generally, glass substrates such as soda-lime glass, borosilicate glass, alkali-free glass, sapphire glass, etc., semiconductor (including compound semiconductor) substrates such as silicon, GaAs, InP, GaN, etc., and metal substrates such as iron, stainless steel, copper, aluminum, etc. are used.

[0157] In the present invention, a glass substrate is particularly preferred. Flat, smooth, and large-area glass substrates have been developed and are easily available. The problem of warping becomes more pronounced as the substrate becomes larger, and glass substrates are relatively prone to warping in terms of rigidity, so the present invention can be applied to solve the problems when using a glass substrate. The thickness of a plate-like substrate such as a glass substrate is not limited, but is, for example, 20 μm to 4 mm, preferably 100 μm to 2 mm, from the viewpoint of ease of handling. The size of the plate-like substrate is not particularly limited, but one side (long side in the case of a rectangle) is, for example, about 100 mm to about 4000 mm, preferably about 200 mm to about 3000 mm, more preferably about 300 mm to about 2500 mm.

[0158] The substrates such as glass substrates may have an inorganic thin film (for example, a silicon oxide film) or a resin thin film formed on the surface.

[0159] The method for casting the polyimide precursor composition onto the substrate is not particularly limited, and examples thereof include conventionally known methods such as slit coating, die coating, blade coating, spray coating, inkjet coating, nozzle coating, spin coating, screen printing, bar coater, and electrodeposition.

[0160] In step (b), the polyimide precursor composition is heat-treated on the substrate to convert it into a polyimide film, and a polyimide film / substrate laminate is obtained. The heat treatment conditions are not particularly limited, but for example, after drying at a temperature range of 50°C to 150°C, the maximum heating temperature is, 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 a polyimide solution is used are not particularly limited, but for example, the maximum heating temperature is 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.

[0161] The thickness of the polyimide film is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 5 μm or more. If the thickness is less than 1 μm, the polyimide film cannot maintain sufficient mechanical strength, and may be destroyed due to inability to withstand stress when used, for example, as a flexible electronic device substrate. The thickness of the polyimide film is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less. If the thickness of the polyimide film is too thick, it may be difficult to thin the flexible device. In order to make the polyimide film thinner while maintaining sufficient resistance as a flexible device, the thickness of the polyimide film is preferably 2 to 50 μm.

[0162] Furthermore, in one embodiment of the present invention, the polyimide film preferably has a breaking elongation of 10% or more when the film has a thickness of 10 μm.

[0163] In another preferred embodiment of the present invention, the breaking strength of the polyimide film is preferably 150 MPa or more, more preferably 170 MPa or more, even more preferably 180 MPa or more, even more preferably 200 MPa or more, and even more preferably 210 MPa or more. The breaking strength may be, for example, a value obtained from a film having a thickness of about 5 to 100 μm.

[0164] It is particularly preferred that the above-mentioned preferable properties for the polyimide film and laminate be satisfied simultaneously.

[0165] The polyimide film in the polyimide film / substrate laminate may have a second layer such as a resin film or an inorganic film on the surface. That is, after forming a polyimide film on a substrate, a second layer may be laminated to form a flexible electronic device substrate. It is preferable to have at least an inorganic film, and it is particularly preferable to have one that functions as a barrier layer against water vapor, oxygen (air), etc. As the water vapor barrier layer, for example, silicon nitride (SiN x ), silicon oxide (SiO x ), silicon oxynitride (SiOx N y Examples of the inorganic film include inorganic films containing an inorganic material selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides, such as aluminum oxide (Al2O3), titanium oxide (TiO2), and zirconium oxide (ZrO2). Generally, known methods for forming these thin films include physical vapor deposition methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (chemical vapor deposition methods) such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD). This second layer can also be a multi-layer structure.

[0166] When the second layer is a multi-layer structure, it is also possible to combine a resin film and an inorganic film. For example, a three-layer structure of a barrier layer / polyimide layer / barrier layer may be formed on the polyimide film in a polyimide film / substrate laminate.

[0167] In step (c), at least one layer selected from a conductive layer and a semiconductor layer is formed on a polyimide film (including a polyimide film having a second layer such as an inorganic film laminated on its surface) using the polyimide / substrate laminate obtained in step (b). These layers may be formed directly on the polyimide film (including a polyimide film having a second layer laminated on its surface) or may be formed indirectly on top of other layers required for the device.

[0168] The conductive layer and / or the semiconductor layer are selected from appropriate conductive layers and (inorganic, organic) semiconductor layers according to the elements and circuits required for the target electronic device. When at least one of the conductive layer and the semiconductor layer is formed in the step (c) of the present invention, it is also preferable to form at least one of the conductive layer and the semiconductor layer on a polyimide film having an inorganic film formed thereon.

[0169] The conductive layer and the semiconductor layer include both those formed on the entire surface of the polyimide film and those formed on a part of the polyimide film. In the present invention, the process may proceed to the step (d) immediately after the step (c), or the process may proceed to the step (d) after forming at least one layer selected from the conductive layer and the semiconductor layer in the step (c) and then forming a device structure.

[0170] When manufacturing a TFT liquid crystal display device as a flexible device, for example, metal wiring, amorphous silicon or polysilicon TFT, and transparent pixel electrodes are formed on a polyimide film having an inorganic film formed on the entire surface as necessary. The TFT includes, for example, a gate metal layer, a semiconductor layer such as an amorphous silicon film, a gate insulating layer, and wiring connected to the pixel electrode. On top of this, a structure required for the liquid crystal display can be further formed by a known method. Also, a transparent electrode and a color filter may be formed on the polyimide film.

[0171] When an organic EL display is produced, for example, a polyimide film having an inorganic film formed over its entire surface as required may be coated with a transparent electrode, a light-emitting layer, a hole transport layer, an electron transport layer, and the like, and in addition, a TFT may be formed as required.

[0172] Since the polyimide film preferred in the present invention is excellent in various properties such as heat resistance and toughness, there are no particular limitations on the method for forming circuits, elements and other structures required for devices.

[0173] Next, in step (d), the substrate and the polyimide film are peeled off by a mechanical peeling method in which the substrate is physically peeled off by applying an external force, or by a so-called laser peeling method in which the substrate is peeled off by irradiating the substrate with a laser beam.

[0174] After the base material is peeled off, the (semi-)finished product is made of the polyimide film as a substrate, and the structures or parts required for the device are further formed or incorporated into the product to complete the device. EXAMPLES

[0175] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0176] In the following examples, evaluations were carried out in the following manner.

[0177] <Evaluation of polyimide precursor solution (varnish)> [Imidization rate] The polyimide precursor solution was dissolved in dimethyl sulfoxide-d6 using a JEOL M-AL400. 1 H-NMR measurement was performed, and the imidization ratio [the content of the repeating unit represented by chemical formula (2) relative to all repeating units] was calculated from the ratio of the integral value of the aromatic proton peak to the integral value of the carboxylic acid proton peak according to the following formula (I).

[0178] Imidization rate (%) = {X-(Y / Z) x A} / 2 x 100 (I) X: integral value of amide proton peak when imidization rate is 0%, calculated from the amount of monomer Y: 1 Integration value of amide proton peak obtained from H-NMR measurement Z: 1 Aromatic proton peak integrals obtained from H-NMR measurements A: The integral value of the aromatic proton peak calculated from the amount of monomer charged

[0179] <Evaluation of polyimide film> [400nm light transmittance] The light transmittance at 400 nm of a polyimide film having a thickness of about 10 μm was measured using a UV-visible spectrophotometer / V-650DS (manufactured by JASCO Corporation). [Yellowness (YI)] The YI of the polyimide film was measured using a UV-Visible Spectrophotometer / V-650DS (manufactured by JASCO Corporation) in accordance with the standard of ASTEM E313. The light source was D65 and the viewing angle was 2°.

[0180] [Elastic modulus, elongation at break, strength at break] A polyimide film with a thickness of approximately 10 μm was punched into a dumbbell shape according to the IEC 450 standard to prepare a test piece, and the initial elastic modulus, breaking elongation, and breaking strength were measured using an ORIENTEC TENSILON with a chuck length of 30 mm and a tensile speed of 2 mm / min.

[0181] [Coefficient of Linear Thermal Expansion (CTE)] A polyimide film with a thickness of approximately 10 μm was cut into a strip with a width of 4 mm to prepare a test piece, and the test piece was heated to 500°C using a TMA / SS6100 (manufactured by SII Nano Technology Co., Ltd.) with a chuck length of 15 mm, a load of 2 g, and a heating rate of 20°C / min. The linear thermal expansion coefficient from 150°C to 250°C was calculated from the obtained TMA curve.

[0182] [5% weight loss temperature] A polyimide film with a thickness of approximately 10 μm was used as a test piece, and the temperature was raised from 25° C. to 600° C. at a rate of 10° C. / min in a nitrogen stream using a calorimeter measuring device (Q5000IR) manufactured by TA Instruments. The 5% weight loss temperature was determined from the obtained weight curve.

[0183] <Ingredients> The abbreviations, purities, etc. of the raw materials used in each of the following examples are as follows.

[0184] [Diamine component] DABAN: 4,4'-diaminobenzanilide PPD: p-phenylenediamine BAPB: 4,4'-bis(4-aminophenoxy)biphenyl TPE-Q: 1,4-bis(4-aminophenoxy)benzene TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0185] [Tetracarboxylic acid component] CpODA: Norbornane-2-spiro-α-cyclopentanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic dianhydride DNDAxx: (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic dianhydride PMDA-H: Cyclohexanetetracarboxylic dianhydride CBDA: Cyclobutanetetracarboxylic dianhydride

[0186] [Imidazole compounds] 2-Pz: 2-phenylimidazole Bz: Benzimidazole 2-Mz: 2-methylimidazole

[0187] [solvent] NMP: N-methyl-2-pyrrolidone DMAc: Dimethylacetamide

[0188] Table 1-1 shows the structural formulae of the tetracarboxylic acid components and diamine components used in the examples and comparative examples, and Table 1-2 shows the structural formulae of the imidazole compounds used in the examples and comparative examples.

[0189] [Table 1-1]

[0190] [Table 1-2]

[0191] <Example 1> [Preparation of polyimide precursor composition] 2.27g (0.010 mol) of DABAN was placed in a reaction vessel purged with nitrogen gas, and 32.11g of N-methyl-2-pyrrolidone was added in an amount such that the total mass of the charged monomers (total of diamine components and carboxylic acid components) was 16% by mass, and the mixture was stirred at 50°C for 1 hour. 3.84g (0.010 mol) of CpODA was gradually added to this solution. The mixture was stirred at 70°C for 4 hours to obtain a uniform and viscous polyimide precursor solution.

[0192] 2-phenylimidazole as an imidazole compound was dissolved in 4 times the mass of N-methyl-2-pyrrolidone to obtain a uniform solution with a solid concentration of 2-phenylimidazole of 20 mass%. The imidazole compound solution was mixed with the polyimide precursor solution synthesized above so that the amount of the imidazole compound was 0.025 moles per mole of the repeating unit of the polyimide precursor, and the mixture was stirred at room temperature for 3 hours to obtain a uniform and viscous polyimide precursor composition. The imidization rate of the polyimide precursor in the obtained polyimide precursor composition was measured and found to be 18%.

[0193] [Production of polyimide film] A 6-inch Corning Eagle-XG (registered trademark) (500 μm thick) was used as the glass substrate. The polyimide precursor composition was applied onto the glass substrate by a spin coater, and the composition was heated from room temperature to 415° C. on the glass substrate in a nitrogen atmosphere (oxygen concentration 200 ppm or less) to thermally imidize the composition, thereby obtaining a polyimide film / substrate laminate. The laminate was immersed in water at 40° C. (for example, in a temperature range of 20° C. to 100° C.) to peel the polyimide film from the glass substrate, and after drying, the properties of the polyimide film were evaluated. The thickness of the polyimide film was about 10 μm. The evaluation results are shown in Table 2.

[0194] <Examples 2 to 10> In Example 1, except that the imidazole compound was changed to a compound shown in Table 2 (blanks indicate no addition), polyimide precursor compositions containing polyimide precursors having an imidization rate shown in Table 2 were obtained in the same manner as in Example 1. Thereafter, polyimide films were produced in the same manner as in Example 1, and the physical properties of the films were evaluated. The results are shown in Table 2. Among Examples 1 to 10, the polyimide precursor compositions of Examples 1 to 5 and 8 to 10 were also very excellent in long-term stability. All physical properties of Examples 1 to 5 were excellent.

[0195] <Examples 11 to 17 and Comparative Examples 1 to 3> In Example 1, the imidazole compound was changed to a compound shown in Table 3. In addition, by changing the temperature and time after adding CpODA in Example 1, a polyimide precursor composition containing a polyimide precursor having an imidization rate shown in Table 3 was obtained. Thereafter, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated. The results are shown in Table 3.

[0196] <Examples 18 to 22 and Comparative Example 4> In Example 1, the diamine component and the imidazole compound were changed to the compounds shown in Table 4. In addition, by changing the temperature and time after the addition of CpODA in Example 1, a polyimide precursor composition containing a polyimide precursor having an imidization rate shown in Table 4 was obtained. Thereafter, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated. The results are shown in Table 4.

[0197] <Examples 23 to 29, Comparative Examples 5 and 6> In Example 1, the tetracarboxylic acid component, the diamine component, and the imidazole compound were changed to the compounds shown in Table 5. In addition, by changing the temperature and time after the addition of CpODA in Example 1, a polyimide precursor composition containing a polyimide precursor having an imidization rate shown in Table 5 was obtained. Thereafter, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated. The results are shown in Table 5.

[0198] <Comparative Examples 7 to 10> In Example 1, the tetracarboxylic acid component, the diamine component, and the imidazole compound were changed to the compounds shown in Table 6. In addition, by changing the temperature and time after the addition of CpODA in Example 1, a polyimide precursor composition containing a polyimide precursor having an imidization rate shown in Table 6 was obtained. Thereafter, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated. The results are shown in Table 6.

[0199] <Comparative Example 11> 0.713g (3.136mmol) of DABAN and 1.004g (3.136mmol) of TFMB were placed in a reaction vessel purged with nitrogen gas, and 16.5g of DMAc was added in an amount such that the total mass of the charged monomers (total of diamine components and carboxylic acid components) was 20% by mass, and the mixture was stirred at room temperature for 1 hour. 2.411g (6.272mmol) of CpODA was gradually added to this solution, and the mixture was stirred at room temperature for 24 hours. The temperature was then raised to 160°C, 25mL of toluene was added, and the toluene was refluxed for 10 minutes, after which the toluene was removed and cooled to room temperature to obtain a uniform and viscous polyimide precursor solution (imidization rate: 44%). Then, a polyimide film was produced in the same manner as in Example 1, and the film properties were evaluated. The results are shown in Table 6.

[0200] [Table 2]

[0201] [Table 3]

[0202] [Table 4]

[0203] [Table 5]

[0204] [Table 6]

[0205] From the above results, it was found that a polyimide film obtained from a polyimide precursor composition in which the proportion of CpODA in the tetracarboxylic acid component is 70 mol % or more, the proportion of DABAN in the diamine component is 70 mol % or more, and the imidization rate is in the range of less than 50%, has a high light transmittance at 400 nm, a low linear thermal expansion coefficient, and a high 5% weight loss temperature. [Industrial Applicability]

[0206] The present invention can be suitably applied to the manufacture of flexible electronic devices, for example, display devices such as liquid crystal displays, organic EL displays, and electronic paper, and light-receiving devices such as solar cells and CMOS.

Claims

1. A polyimide precursor comprising a repeating unit represented by the following general formula (I) and a repeating unit in which the general formula (I) is further imidized, and having an imidization rate of 12% or more and less than 50%, solvent wherein the polyimide precursor is dissolved in the solvent and is in a liquid state. 【Chemistry 1】 (In general formula I, X １ is a tetravalent aliphatic or aromatic group; Y １ is a divalent aliphatic or aromatic group, R １ and R ２ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, provided that X １ 70 mol % or more of the formula (1-1): 【Chemistry 2】 The structure represented by Y １ At least 70 mol % of the formula (D-1) and / or (D-2): 【Chemistry 3】 It is a structure represented by the following formula:

2. 2. The polyimide precursor composition according to claim 1, wherein a polyimide film obtained from the polyimide precursor composition has a light transmittance of 79% or more at a wavelength of 400 nm when the film has a thickness of 10 μm.

3. 3. The polyimide precursor composition according to claim 1, wherein a polyimide film obtained from the polyimide precursor composition has a linear thermal expansion coefficient of 20 ppm / K or less between 150° C. and 250° C. in a film having a thickness of 10 μm.

4. 4. The polyimide precursor composition according to claim 1, wherein a polyimide obtained from the polyimide precursor composition has a 5% weight loss temperature of 500° C. or higher.

5. 5. The polyimide precursor composition according to claim 1, wherein a polyimide film obtained from the polyimide precursor composition has a breaking elongation of 10% or more for a film having a thickness of 10 μm.

6. X １ 6. The polyimide precursor composition according to claim 1, wherein 90 mol % or more of the structure represented by formula (1-1) is

7. A polyimide film obtained from the polyimide precursor composition according to any one of claims 1 to 6.

8. A polyimide film obtained from the polyimide precursor composition according to any one of claims 1 to 6; Substrate and A polyimide film / substrate laminate comprising:

9. The laminate according to claim 8 , wherein the substrate is a glass substrate.

10. (a) applying the polyimide precursor composition according to any one of claims 1 to 6 onto a substrate; and (b) a step of heat-treating the polyimide precursor on the substrate and laminating a polyimide film on the substrate; A method for producing a polyimide film / substrate laminate having the above structure.

11. The method according to claim 10 , wherein the substrate is a glass substrate.

12. (a) applying the polyimide precursor composition according to any one of claims 1 to 6 onto a substrate; (b) heat-treating the polyimide precursor on the substrate to produce a polyimide film / substrate laminate in which a polyimide film is laminated on the substrate; (c) forming at least one layer selected from a conductive layer and a semiconductor layer on the polyimide film of the laminate; and (d) peeling the polyimide film from the substrate A method for producing a flexible electronic device comprising the steps of:

13. The method according to claim 12 , wherein the substrate is a glass substrate.

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