CN114423823B - Polyimide precursor composition and method for manufacturing flexible electronic device - Google Patents

Abstract

Disclosed is a polyimide precursor composition comprising a polyimide precursor, a phosphorus compound having a P(=O)OH structure or a P(=O)OR structure (wherein R is an alkyl group having 4 or more carbon atoms), and a solvent. The composition can be used to manufacture a flexible electronic device using an industrially simple device.

Description

Polyimide precursor composition and method for manufacturing flexible electronic device

Technical Field

The present invention relates to a polyimide precursor composition suitable for use in electronic devices such as substrates of flexible devices and a method for producing a flexible electronic device.

Background Art

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

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

Polyimide is generally colored yellow-brown, and therefore its use in transmissive devices such as liquid crystal displays with backlights is limited. However, in recent years, polyimide films having excellent transparency in addition to mechanical and thermal properties have been developed, and expectations for their use as substrates for display applications have further increased (see Patent Documents 1 to 3).

Generally, it is difficult to maintain the planarity of a flexible film, and therefore it is difficult to uniformly and accurately form semiconductor elements such as TFTs, fine wiring, etc. on the flexible film. For example, Patent Document 4 describes "a method for manufacturing a flexible device as a display device or a light receiving device, which includes the following steps: a step of coating a specific precursor resin composition on a carrier substrate to form a film to form a solid polyimide resin film; a step of forming a circuit on the resin film; and a step of peeling the solid resin film with the circuit formed on the surface from the carrier substrate."

In addition, Patent Document 5 discloses a method for manufacturing a flexible device, which includes: after forming components and circuits required for the device on a polyimide film/glass substrate laminate obtained by forming a polyimide film on a glass substrate, irradiating the glass substrate with laser from the glass substrate side to peel off the glass substrate.

Prior art literature

Patent Literature

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: Japanese Patent Application Publication No. 2010-202729

Patent Document 5: International Publication No. 2018/221607

Patent Document 6: International Publication No. 2012/173204

Patent Document 7: International Publication No. 2015/080139

Summary of the invention

Problems to be solved by the invention

The mechanical peeling described in Patent Document 4 has the advantages of being simple and convenient without the need for additional equipment, but the peeling strength between the polyimide film and the glass substrate is too large, and when the polyimide film is peeled off from the glass substrate, it sometimes causes damage to the components and circuits formed on the polyimide film. On the other hand, the laser peeling described in Patent Document 5 can ensure high adhesion between the polyimide film and the glass substrate when the components and circuits are formed, and can reduce the peeling strength during peeling, so it has the advantage of less damage to the components and circuits. However, a laser irradiation device is required, and the equipment cost increases.

By the way, Patent Document 6 describes a composition in which monoethyl phosphate (Example 4), monolauryl phosphate (Example 5), and polyphosphoric acid (Example 6) are added to a polyimide precursor solution obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine, respectively. However, there is no description of reducing the peel strength between the polyimide film formed on the substrate and the substrate by adding these phosphorus compounds, and manufacturing flexible electronic devices.

In addition, Patent Document 7 describes as comparative examples the addition of phosphoric acid (Comparative Example 2) and tributyl phosphate (Comparative Example 4) to a polyimide precursor solution having specific components, but does not describe at all that the addition of these phosphorus compounds reduces the peel strength between the polyimide film formed on the substrate and the substrate.

The present invention has been made in view of the conventional problems, and its main object is to provide a polyimide precursor composition capable of producing a flexible electronic device by an industrially simple device and process, and a method for producing a flexible electronic device.

Means for solving problems

A summary of the main disclosed matters of this application is as follows.

1. A polyimide precursor composition (which satisfies the following condition (A)), characterized in that it contains:

Polyimide precursor;

A phosphorus compound having a P(═O)OH structure or a P(═O)OR (wherein R is an alkyl group having 4 or more carbon atoms) structure in an amount exceeding 0.001 mol % and less than 5 mol % relative to the total monomer units of the polyimide precursor; and

Solvent.

(A) The polyimide precursor is not a polyimide precursor obtained only from 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine.

2. The composition according to item 1 above, wherein the content of the phosphorus compound is 0.01 mol% or more based on the total monomer units of the polyimide precursor.

3. The composition according to item 1 or 2 above, wherein the phosphorus compound does not include a compound having an aromatic group directly bonded to P.

4. The composition according to any one of items 1 to 3 above, wherein the phosphorus compound has a molecular weight of less than 400.

5. The composition according to any one of items 1 to 4 above, wherein the polyimide precursor comprises a repeating unit selected from a structure represented by the following general formula (I) and a structure in which at least one amide structure in the general formula (I) is imidized.

[Chemistry 1]

(In general formula I, _X1 is a tetravalent aliphatic group or aromatic group, _Y1 is a divalent aliphatic group or aromatic group, and _R1 and _R2 are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

6. The composition according to item 5 above, wherein the content of the repeating unit represented by the general formula (I) in which _X1 is a tetravalent group having an alicyclic structure and _Y1 is a divalent group having an alicyclic structure is 50 mol% or less based on all the repeating units.

7. The composition according to item 5 above, wherein _X1 in the general formula (I) is a tetravalent group having an aromatic ring, and _Y1 is a divalent group having an aromatic ring.

8. The composition according to item 5 above, wherein _X1 in the general formula (I) is a tetravalent group having an alicyclic structure, and _Y1 is a divalent group having an aromatic ring.

9. The composition according to item 5 above, wherein _X1 in the general formula (I) is a tetravalent group having an aromatic ring, and _Y1 is a divalent group having an alicyclic structure.

10. The composition according to item 5 above, characterized in that it contains repeating units in which _X1 of the general formula (I) is a tetravalent group having an alicyclic structure at a ratio exceeding 60% of all repeating units (wherein the content of repeating units represented by the general formula (I) in which _X1 is a tetravalent group having an alicyclic structure and _Y1 is a divalent group having an alicyclic structure is 50 mol% or less relative to all repeating units).

11. A method for manufacturing a flexible electronic device, comprising:

(a) a step of applying a polyimide precursor composition containing a polyimide precursor, a phosphorus compound having a P(=O)OH structure or a P(=O)OR structure (wherein R is an alkyl group having 4 or more carbon atoms), and a solvent onto a substrate;

(b) a step of heat-treating the polyimide precursor on the substrate to produce a laminate having a polyimide film laminated on the substrate;

(c) forming at least one layer selected from a conductor layer and a semiconductor layer on the polyimide film of the laminate; and

(d) A step of peeling the substrate and the polyimide film apart by an external force.

12. The production method according to item 11 above, wherein the polyimide precursor composition is the polyimide precursor composition according to any one of items 1 to 10 above.

13. The production method according to item 11 or 12 above, wherein the substrate is a glass plate.

14. The production method according to any one of the above Items 11 to 13, wherein laser irradiation is not performed in the step of peeling the substrate and the polyimide film.

15. A method for reducing the peel strength of a laminate, which is a method for reducing the peel strength between a substrate and a polyimide film formed on the substrate, wherein the laminate comprises:

The polyimide precursor composition for forming the polyimide film contains a phosphorus compound having a P(═O)OH structure or a P(═O)OR structure (wherein R is an alkyl group having 4 or more carbon atoms).

16. The method according to item 15 above, wherein the polyimide precursor composition is the polyimide precursor composition according to any one of items 1 to 10 above.

17. The method according to item 15 or 16 above, wherein the substrate is a glass plate.

Effects of the Invention

According to the present invention, a polyimide precursor composition capable of manufacturing a flexible electronic device by an industrially simple device and process can be provided. In addition, according to the present invention, a simple method for manufacturing a flexible electronic device using a polyimide film as a substrate can be provided. If the polyimide precursor composition of the present invention is used, the peel strength between the substrate and the polyimide film can be appropriately reduced. Therefore, a flexible electronic device can be manufactured by a simple device and process, and the possibility of damage to the element is small, and it can be manufactured with a good yield.

DETAILED DESCRIPTION

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

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

<<Polyimide Precursor Composition>>

The polyimide precursor composition for forming a polyimide film contains a polyimide precursor, a phosphorus compound, and a solvent. The polyimide precursor and the phosphorus compound are both dissolved in the solvent.

In the present application, the term "polyimide precursor" is used to mean a precursor of a polyimide that can form a polyimide in a polyimide film. That is, the term "polyimide precursor" includes polyamic acid and derivatives (defined precisely by formula (I)), partially imidized partially imidized polyamic acid and derivatives, and polyimide, all dissolved in a solvent.

The polyimide precursor has a repeating unit represented by the following general formula (I): A polyamic acid in which _R1 and _R2 are hydrogen atoms is particularly preferred.

[Chemistry 2]

(In general formula I, _X1 is a tetravalent aliphatic group or aromatic group, _Y1 is a divalent aliphatic group or aromatic group, and _R1 and _R2 are independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.)

In addition, the partially imidized polyimide precursor includes a repeating unit in which at least one of the two amide structures in the general formula (I) is imidized.

The polyimide formed from the polyimide precursor having a repeating unit represented by the general formula (I) has a repeating unit represented by the following general formula (II).

[Chemistry 3]

(In the formula, _X1 is a tetravalent aliphatic group or an aromatic group, and _Y1 is a divalent aliphatic group or an aromatic group.)

In the case of a soluble polyimide, it can be contained in a polyimide precursor composition as a "polyimide precursor".

The chemical structure of such polyimide will be described below using the structures of _X1 and _Y2 in the above repeating units (general formulas (I) and (II)) and the monomers (tetracarboxylic acid component, diamine component, and other components) used in the production, and then the production method will be described.

In this specification, the tetracarboxylic acid component includes tetracarboxylic acid, tetracarboxylic dianhydride, and tetracarboxylic acid derivatives such as tetracarboxylic acid silyl ester, tetracarboxylic acid ester, and tetracarboxylic acid chloride used as raw materials for producing polyimide. Although not particularly limited, it is convenient to use tetracarboxylic dianhydride in production, and in the following description, an example using tetracarboxylic dianhydride as the tetracarboxylic acid component is described. In addition, the diamine component is a diamine compound having two amino groups (-NH ₂ ) used as a raw material for producing polyimide.

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

The polyimide contained in the polyimide film is not particularly limited, and the tetracarboxylic acid component and the diamine component are appropriately composed of a polyimide selected from an aromatic compound and an aliphatic compound. The aliphatic compound of the diamine component is preferably an alicyclic compound. As the polyimide, for example, a fully aromatic polyimide, a semi-alicyclic polyimide, and a fully alicyclic polyimide can be cited.

Although not particularly limited, since the obtained polyimide material has excellent heat resistance, it is preferred that _X1 in the general formula (I) is a tetravalent group having an aromatic ring and _Y1 is a divalent group having an aromatic ring. In addition, since the obtained polyimide material has excellent heat resistance and excellent transparency, it is preferred that _X1 is a tetravalent group having an alicyclic structure and _Y1 is a divalent group having an aromatic ring. In addition, since the obtained polyimide material has excellent heat resistance and excellent dimensional stability, it is preferred that _X1 is a tetravalent group having an aromatic ring and _Y1 is a divalent group having an alicyclic structure.

From the perspective of the properties of the obtained polyimide material, such as transparency, mechanical properties or heat resistance, the content of the repeating unit represented by formula (I) in which _X1 is a tetravalent group having an alicyclic structure and _Y1 is a divalent group having an alicyclic structure is preferably 50 mol% or less, more preferably 30 mol% or less or less than 30 mol%, more preferably 10 mol% or less, relative to all the repeating units.

In a certain embodiment, the total content of one or more repeating units of the above-mentioned formula (I) in which _X is a tetravalent group having an aromatic ring and _Y is a divalent group having an aromatic ring is preferably 50 mol% or more, more preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and particularly preferably 100 mol% relative to all repeating units. In this embodiment, in particular, in the case of a polyimide material requiring high transparency, the polyimide preferably contains fluorine atoms. That is, the polyimide preferably includes one _or more repeating units of the above-mentioned general formula (I) in which _X is a tetravalent group having an aromatic ring containing fluorine atoms and/or Y is a divalent group having an aromatic ring containing fluorine atoms.

In a certain embodiment, in the polyimide, the total content of one or more repeating units of the general formula (I) in which _X1 is a tetravalent group having an alicyclic structure and _Y1 is a divalent group having an aromatic ring is preferably 50 mol% or more, more preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and particularly preferably 100 mol% relative to all repeating units.

In a certain embodiment, in the polyimide, the total content of one or more repeating units of the above formula (I) in which _X1 is a tetravalent group having an aromatic ring and _Y1 is a divalent group having an alicyclic structure is preferably 50 mol% or more, more preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and particularly preferably 100 mol% relative to all repeating units.

< _X1 and tetracarboxylic acid component>

As the tetravalent group having an aromatic ring represented by _X1 , a tetravalent group having an aromatic ring having 6 to 40 carbon atoms is preferred.

Examples of the tetravalent group having an aromatic ring include the following groups.

[Chemistry 4]

(wherein, _Z1 is a direct bond or any of the following divalent groups.

[Chemistry 5]

Wherein, _Z2 in the formula is a divalent organic group, _Z3 and _Z4 are each independently an amide bond, an ester bond, or a carbonyl bond, and _Z5 is an organic group containing an aromatic ring.

Specific examples of Z ₂ include an aliphatic hydrocarbon group having 2 to 24 carbon atoms and an aromatic hydrocarbon group having 6 to 24 carbon atoms.

Specific examples of Z ₅ include aromatic hydrocarbon groups having 6 to 24 carbon atoms.

As the tetravalent group having an aromatic ring, the following tetravalent groups are particularly preferred because the obtained polyimide film can have both high heat resistance and high transparency.

[Chemistry 6]

(Wherein, _Z1 is a direct bond or a hexafluoroisopropylidene bond.)

Here, _Z1 is more preferably a direct bond because the obtained polyimide film can achieve high heat resistance, high transparency, and a low linear thermal expansion coefficient.

In addition, as a preferred group, in the above formula (9), Z ₁ can be exemplified as the following formula (3A):

[Chemistry 7]

Z ₁₁ and Z ₁₂ are each independently the same and are preferably a single bond or a divalent organic group. Z ₁₁ and Z ₁₂ are preferably organic groups containing an aromatic ring, and for example, the structure represented by formula (3A1) is preferred.

[Chemistry 8]

( _Z13 and _Z14 are independently a single bond, -COO-, -OCO- or -O-. When _Z14 is bonded to a fluorenyl group, preferably, _Z13 is -COO-, -OCO- or -O- and _Z14 is a single bond. _R91 is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably a methyl group. n is an integer of 0 to 4, preferably 1.)

Examples of the tetracarboxylic acid component providing a repeating unit of the general formula (I) in which _X1 is a tetravalent group having an aromatic ring include 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid, 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, dicarboxyphenyldimethylsilane, dicarboxyphenoxydiphenyl sulfide, sulfonyldiphthalic acid, tetracarboxylic acid dianhydride, tetracarboxylic acid silyl ester, tetracarboxylic acid ester, tetracarboxylic acid chloride and other derivatives thereof. As the tetracarboxylic acid component providing the repeating unit of the general formula (I) in which _X1 is a tetravalent group having an aromatic ring containing a fluorine atom, for example, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, tetracarboxylic acid dianhydride, tetracarboxylic acid silyl ester, tetracarboxylic acid ester, tetracarboxylic acid chloride and other derivatives thereof can be cited. Furthermore, as a preferred compound, (9H-fluorene-9,9-diyl)bis(2-methyl-4,1-phenylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) can be mentioned. The tetracarboxylic acid component may be used alone or in combination of two or more.

As the tetravalent group having an alicyclic structure represented by _X1 , a tetravalent group having an alicyclic structure having 4 to 40 carbon atoms is preferred, more preferably having at least one aliphatic 4- to 12-membered ring, more preferably an aliphatic 4-membered ring or an aliphatic 6-membered ring. Examples of the tetravalent group having a preferred aliphatic 4-membered ring or an aliphatic 6-membered ring include the following groups.

[Chemistry 9]

(In the formula, R ₃₁ to R ₃₈ are each independently a direct bond or a divalent organic group. R ₄₁ to R ₄₇ are each independently one selected from the group consisting of groups represented by the formula: -CH ₂ -, -CH=CH-, -CH ₂ CH ₂ -, -O-, and -S-. R ₄₈ is an organic group containing an aromatic ring or an alicyclic structure.)

Specific examples of R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ , R ₃₅ , R ₃₆ , R ₃₇ and R ₃₈ 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.

Examples of the aromatic ring-containing organic group for R ₄₈ include the following groups.

[Chemistry 10]

(In the formula, _W1 is a direct bond or a divalent organic group, _n11 to _n13 each independently represent an integer of 0 to 4, and _R51 , _R52 , and _R53 each independently represent an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group.)

Specific examples of W ₁ include a direct bond, a divalent group represented by the following formula (5), and a divalent group represented by the following formula (6).

[Chemistry 11]

(R ₆₁ to R ₆₈ in formula (6) each independently represent a direct bond or any of the divalent groups represented by formula (5).)

As the tetravalent group having an alicyclic structure, the following groups are particularly preferred because the resulting polyimide can have high heat resistance, high transparency, and a low linear thermal expansion coefficient.

[Chemistry 12]

Examples of the tetracarboxylic acid component providing a repeating unit of the formula (I) in which _X1 is a tetravalent group having an alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic acid, isopropylidene diphenoxy diphthalic 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'-dicarboxylic acid. 4'-(Propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic acid), 4,4'-thiobis(cyclohexane-1,2-dicarboxylic acid), 4,4'-sulfonylbis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid), octahydropentalene-1,3,4,6-tetracarboxylic acid, bicyclo[2.2.1]heptane-2 ,3,5,6-tetracarboxylic acid, 6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3,5-tricarboxylic acid, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2.2.2]oct-5-ene-2,3,7,8-tetracarboxylic acid, tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid, tricyclo[4.2.2.02,5]dec-7-ene-3,4,9,10-tetracarboxylic acid, 9-oxatricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic acid, norbornane- 2-Spiro-α-cyclopentanone-α'-spiro-2"-norbornane 5,5",6,6"-tetracarboxylic acid, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethylnaphthalene-2c,3c,6c,7c-tetracarboxylic acid, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethylnaphthalene-2t,3t,6c,7c-tetracarboxylic acid, and their derivatives such as tetracarboxylic dianhydride, tetracarboxylic acid silyl ester, tetracarboxylic acid ester and tetracarboxylic acid chloride. The tetracarboxylic acid component may be used alone or in combination of two or more.

< _Y1 and diamine component>

As the divalent group having an aromatic ring represented by _Y1 , a divalent group having 6 to 40 carbon atoms is preferred, and a divalent group having 6 to 20 carbon atoms is more preferred.

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

[Chemistry 13]

(In the formula, _W1 is a direct bond or a divalent organic group, _n11 to _n13 each independently represent an integer of 0 to 4, and _R51 , _R52 , and _R53 each independently represent an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group.)

Specific examples of W ₁ include a direct bond, a divalent group represented by the following formula (5), and a divalent group represented by the following formula (6).

[Chemistry 14]

[Chemistry 15]

(R ₆₁ to R ₆₈ in formula (6) each independently represent a direct bond or any of the divalent groups represented by formula (5).)

Here, since the obtained polyimide can have high heat resistance, high transparency and low linear thermal expansion coefficient, _W1 is particularly preferably a direct bond or one selected from the group consisting of groups represented by the formula: -NHCO-, -CONH-, -COO-, and -OCO-. In addition, _W1 is also particularly preferably any of the divalent groups represented by the above formula (6) in which R ₆₁ to R ₆₈ are a direct bond or one selected from the group consisting of groups represented by the formula: -NHCO-, -CONH-, -COO-, and -OCO-.

In addition, as a preferred group, in the above formula (4), W ₁ can be exemplified as the following formula (3B):

[Chemistry 16]

The fluorenyl-containing group compound shown in FIG. Z ₁₁ and Z ₁₂ are each independently preferably the same and are a single bond or a divalent organic group. Z ₁₁ and Z ₁₂ are preferably organic groups containing an aromatic ring, and for example, the structure shown in formula (3B1) is preferred.

[Chemistry 17]

(Z ₁₃ and Z ₁₄ are independently a single bond, -COO-, -OCO- or -O-. When Z ₁₄ is bonded to a fluorenyl group, preferably, Z ₁₃ is -COO-, -OCO- or -O- and Z ₁₄ is a single bond. R ₉₁ is an alkyl group having 1 to 4 carbon atoms or a phenyl group, preferably a phenyl group. n is an integer of 0 to 4, preferably 1.)

As other preferred groups, in the above formula (4), compounds in which W ₁ is a phenylene group, that is, terphenylenediamine compounds can be mentioned, and compounds in which all of them are bonded at the para position are particularly preferred.

As another preferred group, in the above formula (4), there can be mentioned a compound in which W ₁ is the structure of the first phenyl ring of formula (6), and R ₆₁ and R ₆₂ are 2,2-propylene groups.

As another preferred group, in the above formula (4), there can be mentioned a compound in which _W1 is represented by the following formula (3B2).

[Chemistry 18]

Examples of the diamine component providing the repeating unit of the general formula (I) in which _Y is a divalent group having an aromatic ring include p-phenylenediamine, m-phenylenediamine, benzidine, 3,3'-diaminobiphenyl, 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-aminophenoxy-4-diaminobenzoate, bis(4-aminophenyl)terephthalamide, 1,4'-diaminophenyl) terephthalate, bis(4-aminophenyl) biphenyl-4,4'-dicarboxylate, p-phenylene bis(p-aminobenzoate), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylate, [1,1'-biphenyl]-4,4'-diylbis(4-aminobenzoate), 4,4'-oxydiphenylamine, 3,4'-oxydiphenylamine, 3,3'-oxydiphenylamine, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-amino phenoxy)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 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine. Examples of the diamine component providing 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. 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'-binaphthyl]-2,2'-diylbis(oxy))diamine. The diamine components may be used alone or in combination of two or more.

The divalent group having an alicyclic structure represented by _Y1 is preferably a divalent group having an alicyclic structure having 4 to 40 carbon atoms, more preferably having at least one aliphatic 4- to 12-membered ring, and more preferably an aliphatic 6-membered ring.

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

[Chemistry 19]

(In the formula, V ₁ and V ₂ are each independently a direct bond or a divalent organic group, n ₂₁ to n ₂₆ are each independently an integer of 0 to 4, R ₈₁ to R ₈₆ are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group, and R ₉₁ , R ₉₂ , and R ₉₃ are each independently one selected from the group consisting of groups represented by the formula: -CH ₂ -, -CH＝CH-, -CH ₂ CH ₂ -, -O-, and -S-.)

Specific examples of V ₁ and V ₂ include a direct bond and a divalent group represented by the above formula (5).

As the divalent group having an alicyclic structure, the following groups are particularly preferred because the resulting polyimide can have both high heat resistance and a low linear thermal expansion coefficient.

[Chemistry 20]

As the divalent group having an alicyclic structure, the following groups are preferred.

[Chemistry 21]

Examples of the diamine component providing a repeating unit of the general formula (I) in which _Y 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-diaminocyclohexane, 1,4 ... Butane, 1,4-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, diaminobicycloheptane, diaminomethylbicycloheptane, diaminooxybicycloheptane, diaminomethoxybicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, isopropylidenebis(aminocyclohexane), 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane. The diamine components may be used alone or in combination of two or more.

In a preferred embodiment of the invention relating to the polyimide precursor, the polyimide precursor is not a polyimide precursor obtained only from 3,3',4,4'-biphenyltetracarboxylic acid derivative (dianhydride) and p-phenylenediamine. Preferably, the ratio of repeating units in which X ₁ in the general formula (I) is derived from 3,3',4,4'-biphenyltetracarboxylic acid derivative (s-BPDA, etc.) and Y ₁ is derived from p-phenylenediamine (PPD) is 25 mol% or less, more preferably 10 mol% or less, and also preferably 0 mol% (excluding at least one of s-BPDA, etc. and PPD) in all repeating units.

In a preferred embodiment of the invention relating to the polyimide precursor, the polyimide precursor and the polyimide are not obtained only from a tetracarboxylic acid derivative (dianhydride) having an aromatic ring and not containing fluorine atoms and a diamine compound having an aromatic ring and not containing fluorine atoms. That is, it is preferred to include a repeating unit in which at least one of X ₁ and Y ₁ of the general formula (I) is a group having an alicyclic structure or a group having an aromatic ring containing fluorine atoms. Preferably, the ratio of the repeating unit in which X ₁ of the general formula (I) is a group having an aromatic ring (excluding a fluorine-containing group) and Y ₁ is a group having an aromatic ring (excluding a fluorine-containing group) is less than 25 mol% of all repeating units, more preferably less than 10 mol%, and also preferably 0 mol% (at least one of X ₁ and Y ₁ is not a group having an aromatic ring and not containing fluorine atoms).

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

Among them, a preferred embodiment of the present invention contains a repeating unit in which X 1 of the general formula (I) is _a quaternary group having an alicyclic structure at a ratio exceeding 60% of the total repeating units, more preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and particularly preferably 100 mol%. When the alicyclic structure is less than 100%, the remaining part is preferably a quaternary group having an aromatic ring. The preferred quaternary group having an alicyclic structure and the quaternary group having an aromatic ring are as described above. In addition, Y ₁ can be any one of a divalent group having an aromatic ring and a divalent group having an alicyclic structure. As _{described above, the content of the repeating unit represented by formula (I) in which X 1 is a quaternary group having an alicyclic structure and Y 1 is a} divalent group having an alicyclic structure is preferably 50 mol% or less, more preferably 30 mol% or less or less than 30 mol%, more preferably 10 mol% or less is preferred relative to the total repeating units.

In another preferred embodiment of the present invention, the polyimide (and polyimide material) is preferably a polyimide having a breaking strength of 80 MPa or more when formed into a film. The breaking strength can be, for example, a value obtained from a film having a film thickness of about 5 to 100 μm. In addition, the breaking strength is a value obtained for a film obtained by heating a coating film of a polyimide precursor solution composition or a polyimide solution composition at a preferred maximum temperature of 310°C.

The polyimide precursor can be prepared from the above-mentioned tetracarboxylic acid component and diamine component. According to the chemical structure taken by _R1 and _R2 , the polyimide precursor used in the present invention (a polyimide precursor comprising at least one of the repeating units represented by the above-mentioned formula (I)) can be classified as follows:

1) Polyamic acid ( _R1 and _R2 are hydrogen);

2) polyamic acid ester (at least a part of _R1 and _R2 is an alkyl group);

3) 4) Polyamic acid silyl ester (at least a part of _R1 and _R2 is an alkylsilyl group).

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

1) Polyamic acid

The polyimide precursor can be suitably obtained in the form of a polyimide precursor solution by reacting tetracarboxylic dianhydride and a diamine component as a tetracarboxylic acid component in a solvent in an approximately equimolar ratio, preferably a molar ratio of the diamine component to the tetracarboxylic acid component [the number of moles of the diamine component/the number of moles of the tetracarboxylic acid component] 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 imidization.

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

2) Polyamic acid ester

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

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

3) Polyamic acid silyl ester (indirect method)

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

4) Polyamic acid silyl ester (direct method)

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

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

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

The solvent used in preparing the polyimide precursor is preferably water, or a non-protonic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide, etc. As long as it can dissolve the raw material monomer components and the generated polyimide precursor, any type of solvent can be used without problem, so there is no particular limitation on its structure. As the solvent, it is preferred to use water, or amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and N-ethyl-2-pyrrolidone, cyclic ester solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, and α-methyl-γ-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, cyclopentane, dimethyl sulfoxide, and the like. In addition, other common organic solvents may be used, i.e., phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpentine, mineral spirits, naphtha-based solvents, etc. It should be noted that two or more solvents may be used in combination.

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

The imidization rate of the polyimide precursor can be used in a wide range of about 0% (less than 5%) to about 100% (more than 95%). The polyimide precursor (polyamic acid, polyamic acid ester, polyamic acid silyl ester) obtained by the above method has a low imidization rate. They are imidized (thermal imidization, chemical imidization) in a solution and imidized, which can be adjusted to the desired imidization rate. For example, the polyamic acid solution is stirred in a range of, for example, 80 to 230° C., preferably 120 to 200° C., for example, for 1 to 24 hours, thereby obtaining a polyimide precursor that has been imidized. When the polyimide is soluble in a solvent, the reaction mixture after the imidization reaction is put into a poor solvent to precipitate the polyimide to obtain a polyimide, or a solution of a polyimide precursor (low imidization rate) (containing an imidization catalyst and a dehydrating agent as needed) is poured onto, for example, a carrier substrate, and heat-treated, dried, and imidized (thermal imidization, chemical imidization). The polyimide thus obtained is dissolved in a solvent and can be used as a polyimide precursor for film manufacturing.

<Phosphorus compounds>

The phosphorus compound that can be used is a compound having at least one structure selected from P(=O)OH and P(=O)OR (wherein R is an alkyl group having 4 or more carbon atoms) in the molecule. The phosphorus compound preferably does not have an aromatic group directly bonded to the phosphorus atom P, and more preferably does not contain an aromatic group in the molecule. The phosphorus compound can have one or more phosphorus atoms in the molecule.

In a preferred embodiment of the present invention, the phosphorus compound contains only one phosphorus atom. Examples of the compound containing one phosphorus atom include compounds represented by formula (P).

[Chemistry 22]

In the formula, at least one of R ₁ to R ₃ represents OH or an alkoxy group having 4 or more carbon atoms, and the remaining groups independently represent a group selected from OH, an alkoxy group, H and an alkyl group.

As the alkoxy group having 4 or more carbon atoms, preferably, an alkoxy group having 4 to 18 carbon atoms can be mentioned, and more preferably, an alkoxy group having 4 to 12 carbon atoms can be mentioned. These may be any of linear, branched, and alicyclic types, and are preferably linear alkoxy groups. As the alkoxy group "the number of carbon atoms is not limited to 4 or more", preferably, an alkoxy group having 1 to 18 carbon atoms can be mentioned, and in addition to the above-mentioned alkoxy groups having 4 or more carbon atoms, an alkoxy group having 1 to 3 carbon atoms can be mentioned.

Examples of the alkyl group include an alkyl group having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, and more preferably 1 to 6 carbon atoms. These may be linear, branched, or alicyclic, and are preferably linear alkyl groups.

When at least one of R ₁ to R ₃ is OH, the remaining groups are not particularly limited, but are preferably selected from OH, alkoxy and alkyl groups. Examples of the combination of R ₁ to R ₃ in this case include all OH (phosphoric acid), 2 OH and 1 alkoxy (monoalkyl phosphate), 1 OH and 2 alkoxy (dialkyl phosphate), 2 OH and 1 alkyl (monoalkyl phosphonate), 1 OH and 2 alkyl (dialkyl phosphinate), and 1 OH, 1 alkoxy and 1 alkyl (monoalkyl phosphinate alkyl).

When at least one of R ₁ to R ₃ is an alkoxy group having 4 or more carbon atoms, the remaining groups are not particularly limited, and are preferably selected from OH, alkoxy groups, and alkyl groups. When OH is included as R ₁ to R ₃ , in the above combination, the corresponding alkoxy group has 4 or more carbon atoms. As a combination of R ₁ to R ₃ selected from alkoxy groups and alkyl groups, all of them are alkoxy groups having 4 or more carbon atoms (trialkyl phosphate), 2 alkoxy groups having 4 or more carbon atoms and 1 alkyl group (monoalkylphosphonic acid dialkyl ester), 1 alkoxy group having 4 or more carbon atoms and 2 alkyl groups (monoalkyldialkylphosphinate) can be cited. When the phosphorus compound contains 2 or more alkoxy groups, they are preferably the same because they are easy to obtain. Therefore, when it is necessary to contain "alkoxy groups having 4 or more carbon atoms" in the compound, the 2 or more alkoxy groups are preferably the same "alkoxy groups having 4 or more carbon atoms".

Examples of phosphorus compounds having two or more phosphorus atoms include polyphosphoric acids such as diphosphoric acid, triphosphoric acid, cyclotriphosphoric acid, and tetraphosphoric acid, and ester compounds thereof (partially or completely esterified compounds). In the case of completely esterified compounds, at least a portion, preferably all, of the alkoxy moieties of the ester are alkoxy groups having 4 or more carbon atoms. In the case of partially esterified compounds, the number of carbon atoms in the alkoxy moiety is not limited, but alkoxy groups having 4 or more carbon atoms are also preferred.

Examples of the phosphorus compound containing two or more phosphorus atoms include compounds having a polyphosphate structure or an oligophosphate structure. Specifically, examples include compounds represented by the general formula (PPE).

[Chemistry 23]

In formula (PPE), R ₁ to R ₃ are each independently a group selected from OH, an alkoxy group, H and an alkyl group, and at least one of R ₁ to R ₃ is OH or an alkoxy group _having 4 or more carbon atoms. R ₄ is a divalent hydrocarbon group. n is an integer of 0 or more.

Preferred groups of R ₁ to R ₃ are the same as those of R ₁ to R ₃ shown for formula (P). Most preferably, all of R ₁ to R ₃ represent an alkoxy group having 4 or more carbon atoms. R ₄ is preferably a hydrocarbon group having 1 to 16 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and is preferably a linear or branched alkylene group. n is preferably 0 to 4, more preferably 0 to 2, and even more preferably 0.

In the present invention, the molecular weight of the phosphorus compound is preferably less than 400 in some cases. In particular, the phosphorus compound represented by the formula (P) and the phosphorus compound represented by the formula (PPE) preferably has a molecular weight of less than 400.

Specific examples of phosphorus compounds include phosphoric acid, methylphosphonic acid, ethylphosphonic acid, n-propylphosphonic acid, isopropylphosphonic acid, n-butylphosphonic acid, sec-butylphosphonic acid, isobutylphosphonic acid, tert-butylphosphonic acid, n-pentylphosphonic acid, isopentylphosphonic acid, neopentylphosphonic acid, n-hexylphosphonic acid, cyclohexylphosphonic acid, heptylphosphonic acid, n-octylphosphonic acid, nonylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, dodecylphosphonic acid, phenylphosphonic acid, (4-hydroxyphenyl)phosphonic acid, methylenediphosphonic acid, 1,2-ethylenediphosphonic acid, o-phenylenedimethyldiphosphonic acid, m-phenylenedimethyldiphosphonic acid, p-phenylenedimethyldiphosphonic acid, dimethylphosphinic acid , ethylmethylphosphinic acid, diethylphosphinic acid, ethylbutylphosphinic acid, dipropylphosphinic acid, phenylphosphinic acid, diphenylphosphinic acid, methylphenylphosphinic acid, (2-carboxyethyl)phenylphosphinic acid, (2-ethylhexyl)phosphonic acid mono-2-ethylhexyl ester, tri-n-butyl phosphate, tri-n-pentyl phosphate, tri-n-hexyl phosphate, tri-(2-ethylhexyl) phosphate, tri-(2-butoxyethyl) phosphate, tri-(1H,1H,5H-octafluoropentyl) phosphate, 2-ethylhexyl diphenyl phosphate, dibutyl phosphite (= dibutyl phosphonate), diisobutyl phosphite (= diisobutyl phosphonate), etc. In the above compounds, the alkyl group may be substituted with structural isomers having the same number of carbon atoms, at least one H in the alkyl group or the aryl group may be substituted with fluorine, and the substitution position in the aryl group is arbitrary. In addition, the phosphorus compound may be used alone or in combination of two or more.

In one embodiment of the present invention, the polyimide precursor composition is sometimes preferably different from the following composition: when the phosphorus compound is phosphoric acid or tributyl phosphate, the polyimide precursor is a polyimide precursor obtained only from norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride (CpODA), 4,4'-diaminobenzanilide (DABAN) and p-phenylenediamine (PPD). In one embodiment of the present invention, the polyimide precursor is sometimes preferably selected from a combination of monomers different from the combination of CpODA, DABAN and PPD.

<Mixing of Polyimide Precursor Composition>

The polyimide precursor composition used in the present invention contains at least one polyimide precursor, at least one phosphorus compound described above, and a solvent.

The content of the phosphorus compound can be adjusted by considering the peel strength between the polyimide film and the substrate. Generally, if it is too little, the peel strength is too large and peeling becomes difficult; on the other hand, if it is too much, not only is it wasteful, but the peel strength becomes extremely small, especially for colorless and transparent polyimide films, the color becomes larger (the yellowness b ^* becomes larger), and sometimes it is not suitable for transparent purposes.

The content of the phosphorus compound is preferably more than 0.001 mol%, more preferably 0.005 mol% or more, further preferably 0.01 mol% or more, further preferably 0.02 mol% or more, further preferably 0.05 mol% or more, relative to the total monomer units of the polyimide precursor (i.e., formula (I) and repeating units of formula (I) are counted as 2 mol%). In addition, it is usually less than 5 mol%, more preferably 4 mol% or less, further preferably 3 mol% or less, and particularly preferably 2 mol% or less.

As the solvent, the above-mentioned solvent described as the solvent used in preparing the polyimide precursor can be used. Usually, the solvent used in preparing the polyimide precursor can be used directly, that is, used in the state of the polyimide precursor solution, but can also be used after dilution or concentration as needed. The phosphorus compound is dissolved and present in the polyimide precursor composition.

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

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

The polyimide precursor composition can be prepared by adding a phosphorus compound or a solution of a phosphorus compound to the polyimide precursor solution obtained by the above method and mixing. The tetracarboxylic acid component and the diamine component may be reacted in the presence of a phosphorus compound unless the reaction is affected.

<<Manufacturing of polyimide/substrate laminate and flexible electronic device>>

The method for manufacturing a flexible electronic device of the present invention comprises: (a) a step of coating a polyimide precursor composition on a substrate; (b) a step of heat-treating the polyimide precursor on the substrate to manufacture a laminate (polyimide/substrate laminate) in which a polyimide film is laminated on the substrate; (c) a step of forming at least one layer selected from a conductor layer and a semiconductor layer on the polyimide film of the laminate; and (d) a step of peeling the substrate and the polyimide film apart by an external force.

The polyimide precursor composition that can be used in the method of the present invention contains a polyimide precursor, a phosphorus compound and a solvent. The phosphorus compound can use the phosphorus compound described in the above-mentioned phosphorus compound. The polyimide precursor can use the polyimide precursor described in the polyimide precursor composition. The polyimide precursor described as a preferred substance in the polyimide precursor composition is also preferred in the method of the present invention, without particular limitation.

One embodiment of the method of the present invention does not include the following method: in step (a), a precursor composition containing phosphoric acid or tributyl phosphate as a phosphorus compound, a tetracarboxylic acid component consisting of CpODA, and a diamine component consisting of a mixture of DABAN and PPD is used as the polyimide precursor composition, and the production of the polyimide/substrate laminate in step (b) is carried out under heating conditions with a maximum temperature of 410° C., preferably 410° C. or higher. Preferably, the following method is not included: in step (a), a precursor composition containing phosphoric acid or tributyl phosphate as a phosphorus compound, a tetracarboxylic acid component consisting of CpODA, and a diamine component consisting of a mixture of DABAN and PPD is used as the polyimide precursor composition.

First, in step (a), a polyimide precursor solution (including an imide solution with a high imidization rate and also including a composition solution containing additives as needed) is poured onto a substrate, and imidization and desolvation (mainly desolvation in the case of a polyimide solution) are carried out by heat treatment to form a polyimide film, thereby obtaining a laminate of the substrate and the polyimide film (polyimide/substrate laminate).

As a substrate, a heat-resistant material is used, such as a plate-like or sheet-like 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-like substrate such as a heat-resistant plastic material (polyimide, etc.). Generally, a planar and smooth plate is preferred, and glass substrates such as soda-lime glass, borosilicate glass, alkali-free glass, and sapphire glass are generally used; semiconductor (including compound semiconductor) substrates such as silicon, GaAs, InP, and GaN; and metal substrates such as iron, stainless steel, copper, and aluminum. In particular, a planar, smooth, and large-area glass substrate is being developed, and it is easy to obtain, so it is preferred. These substrates may have an inorganic film (e.g., a silicon oxide film) or a resin film formed on the surface.

The thickness of the plate-like substrate is not limited, but is, for example, 20 μm to 4 mm, and preferably 100 μm to 2 mm, from the viewpoint of ease of handling.

The method for casting the polyimide precursor solution on the substrate is not particularly limited, and examples thereof include conventionally known methods such as spin coating, screen printing, bar coating, and electrodeposition.

In step (b), the polyimide precursor composition is heat-treated on the substrate to convert it into a polyimide film to obtain a polyimide/substrate laminate. The heat treatment conditions are not particularly limited, and it is preferred that, for example, after drying at a temperature range of 50°C to 150°C, the treatment is performed 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, and the maximum heating temperature is, for example, 100°C to 600°C, preferably 150°C or more, more preferably 200°C or more, and preferably 500°C or less, more preferably 450°C or less.

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

In one embodiment, the polyimide film preferably has excellent optical properties such as 400nm transmittance, total light transmittance (average transmittance of 380nm to 780nm), and yellowness b* (YI). When measured using a film with a thickness of 10μm, the 400nm transmittance is preferably 50% or more, more preferably 70% or more, further preferably 75% or more, and most preferably 80% or more, the total light transmittance is preferably 84% or more, more preferably 85% or more, and the yellowness b* (YI) is preferably 0 or more and 5 or less, more preferably 3 or less. Among the 400nm transmittance, total light transmittance, and yellowness b* (YI), preferably at least 1, more preferably at least 2, and most preferably 3 simultaneously meet the preferred range.

In one embodiment, the polyimide film preferably has a small thickness direction phase difference (retardation) _Rth . In addition, in the polyimide precursor composition of the present invention, the addition of the phosphorus compound specified in the present invention does not substantially change the _Rth of the obtained polyimide film. Therefore, in the present invention, the peel strength between the polyimide film and the substrate can be adjusted without affecting _Rth .

The obtained polyimide film is closely bonded to a substrate such as a glass substrate and laminated. In order to easily implement mechanical peeling, when measured according to JIS K6854-1, for example, in a tensile speed of 2mm/minute and a 90° peel test, the peel strength between the substrate and the polyimide film is preferably 0.8N/in (N/25.4mm) or less, more preferably 0.6N/in or less, and further preferably 0.4N/in or less. On the other hand, the lower limit is preferably 0.01N/in or more. The peel strength is usually measured in air or in the atmosphere.

The polyimide film in the polyimide/substrate laminate may also have a second layer such as a resin film or an inorganic film on the surface. That is, after the polyimide film is formed on the substrate, the second layer is laminated to form a flexible electronic device substrate. It is preferred to have at least an inorganic film, and it is particularly preferred to function as a barrier layer for water vapor or oxygen (air). As a water vapor barrier layer, for example _, an inorganic film _containing an inorganic substance selected from the group consisting of metal oxides, metal nitrides and metal oxynitrides such as silicon nitride ( _SiNx ), silicon oxide ( _SiOx ), silicon oxynitride ( _SiOxNy ), aluminum oxide ( _Al2O3 ), titanium oxide ( _TiO2 ), zirconium oxide ( _ZrO2 ), etc. can be cited. Generally, as a film forming method for these thin films, physical vapor deposition methods such as vacuum evaporation, sputtering, and ion plating, and chemical vapor deposition methods (chemical vapor deposition methods) such as plasma CVD and catalytic chemical vapor deposition (Cat-CVD) are known. The second layer may be a plurality of layers.

In the present invention, the peel strength can be reduced by making the polyimide precursor composition contain a phosphorus compound. Therefore, the present application also discloses an invention related to a method for reducing the peel strength of a laminate, which is a method for reducing the peel strength between the substrate and the polyimide film of a laminate having a substrate and a polyimide film formed on the substrate, characterized in that the polyimide precursor composition used for forming the polyimide film contains the phosphorus compound.

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

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

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

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

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

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

Next, in step (d), the substrate and the polyimide film are physically peeled off by external force. "By external force" means applying force to separate the substrate from the polyimide film. For example, peeling is performed by hand or by using appropriate tools, fixtures, devices, etc. During peeling, one or both of the substrate and the polyimide film will bend, but the range of bending the polyimide film is the range in which the conductor layer, semiconductor layer and other structures formed on the polyimide film are not damaged. For this purpose, tools, fixtures, devices, etc. can be appropriately used for peeling in a manner that the radius of curvature of the polyimide film does not decrease when it is bent. Specifically, for example: (i) a method of peeling by inserting a tool such as a scraper between the substrate and the polyimide film and moving it; (ii) a method of peeling by pulling the film up from the substrate (in this case, a tool such as a scraper can be used); (iii) a method of peeling by bending the substrate while maintaining the planarity of the film as much as possible; etc. Peeling is preferably performed in a gas or vacuum, usually in air or in the atmosphere.

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

In a preferred embodiment of the present invention, the peeling of the substrate and the polyimide film is performed by a peeling method using only an external force without laser irradiation.

In another embodiment of the present invention, the method of the present invention, that is, a method using a polyimide precursor containing a phosphorus compound, can be applied as an auxiliary means when peeling cannot be achieved by laser irradiation alone.

Therefore, another aspect of the present invention relates to a method for manufacturing a flexible electronic device, which comprises:

(a) a step of applying a polyimide precursor composition containing a polyimide precursor, a phosphorus compound having a P(=O)OH structure or a P(=O)OR structure (wherein R is an alkyl group having 4 or more carbon atoms), and a solvent onto a substrate;

(b) a step of heat-treating the polyimide precursor on the substrate to produce a laminate having a polyimide film laminated on the substrate;

(c) forming at least one layer selected from a conductor layer and a semiconductor layer on the polyimide film of the laminate;

(e) a step of irradiating the laminate with laser light; and

(d) A step of peeling the substrate and the polyimide film apart by an external force.

Another aspect of the present invention relates to a method for performing laser peeling when laser irradiation peeling is not possible. When peeling is not possible even by laser irradiation due to reasons such as composition dependence and/or insufficient laser output, laser peeling can be performed by using a polyimide precursor composition containing a phosphorus compound. That is, this aspect relates to a method for manufacturing a flexible electronic device, which is a method having the following steps:

(a2) a step of applying a polyimide precursor composition containing a polyimide precursor and a solvent onto a substrate;

(b2) a step of heat-treating the polyimide precursor on the substrate to produce a laminate having a polyimide film laminated on the substrate;

(c2) forming at least one layer selected from a conductor layer and a semiconductor layer on the polyimide film of the laminate; and

(e2) a step of irradiating the laminate with laser light,

The polyimide precursor composition is characterized in that it contains a phosphorus compound having a P(=O)OH structure or a P(=O)OR structure (wherein R is an alkyl group having 4 or more carbon atoms).

Example

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

<Evaluation of polyimide film>

[b*(YI)]

The b ^* (=YI; yellowness) of a polyimide film having a film thickness of 10 μm and a size of 3 cm square was measured using a UV-visible spectrophotometer/V-650DS (manufactured by JASCO Corporation) according to the standard of ASTEM E313. The light source was D65 and the viewing angle was 2°.

[400nm transmittance, total transmittance]

The light transmittance and total light transmittance (average transmittance at wavelengths of 380 nm to 780 nm) of a 10 μm thick, 5 cm square polyimide film were measured using a UV-visible spectrophotometer V-650DS (manufactured by JASCO Corporation).

[Peel strength]

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

[Glass transition temperature (Tg)]

A polyimide film with a film thickness of about 10 μm was cut into strips with a width of 4 mm to prepare test pieces, and the test pieces were heated to 500° C. using TMA/SS6100 (manufactured by SII Nanotechnology Co., Ltd.) under the conditions of a chuck distance of 15 mm, a load of 2 g, and a heating rate of 20° C./min. The glass transition temperature (Tg) was calculated from the inflection point of the obtained TMA curve.

[1% weight loss temperature (Td1%)]

A polyimide film having a thickness of about 10 μm was used as a test piece and heated from 25° C. to 600° C. at a heating rate of 10° C./min in a nitrogen stream using a calorimeter measuring apparatus (Q5000IR) manufactured by TA INSTRUMENTS. The 1% weight loss temperature was determined from the obtained weight curve.

The abbreviations of the compounds used in the following examples are as follows.

TFMB: 4,4'-bis(trifluoromethyl)benzidine

ODA: 4,4'-diaminodiphenyl ether

4,4'-DDS: 4,4'-diaminodiphenyl sulfone

m-TD: 2,2'-dimethyl-4,4'-diaminobiphenyl

BAFL: 9,9-bis(4-aminophenyl)fluorene

BAPB: 4,4'-bis(4-aminophenoxy)biphenyl

6FDA: 4,4'-(2,2-hexafluoroisopropylene) diphthalic anhydride

PMDA-HS: 1R,2S,4S,5R-cyclohexanetetracarboxylic dianhydride

s-BPDA: 3,3’,4,4’-biphenyltetracarboxylic dianhydride

BPADA: 5,5'-((propane 2-2-diylbis(1,4-phenylene))bis(oxy))bis(isobenzofuran-1,3-dione)

CpODA: Norbornane-2-spiro-α-cyclopentanone-α’-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic dianhydride

CBDA: Cyclobutanetetracarboxylic dianhydride

PPHT: N,N'-(1,4-phenylene)bis(1,3-dioxooctahydroisobenzofuran-5-carboxamide)

[Table 1]

[Table 2]

[Synthesis Example 1]

8.38 g (26.2 mmol) of TFMB was placed in a nitrogen-purged reaction container, and 80.03 g of N-methyl-2-pyrrolidone was added in an amount of 20% by mass of the total mass of the monomers (the sum of the diamine component and the carboxylic acid component), and stirred at room temperature for 30 minutes. 11.62 g (26.2 mmol) of 6FDA was slowly added to the solution. Stirring was carried out at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution.

[Synthesis Example 2]

8.02 g (40.0 mmol) of ODA was placed in a nitrogen-purged reaction vessel, and 83.04 g of N,N-dimethylacetamide was added to a total monomer mass (the sum of the diamine component and the carboxylic acid component) of 17% by mass, and stirred at room temperature for 30 minutes. 8.98 g (40.0 mmol) of PMDA-HS was slowly added to the solution. Stirring was continued at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution.

[Synthesis Example 3]

6.68 g (20.8 mmol) of TFMB was placed in a nitrogen-purged reaction vessel, and 59.99 g of N-methyl-2-pyrrolidone was added in an amount of 20% by mass of the total mass of the monomers fed (the sum of the diamine component and the carboxylic acid component), and stirred at room temperature for 30 minutes. 6FDA 6.48 g (14.6 mmol) and s-BPDA 1.85 g (6.3 mmol) were slowly added to the solution. Stirring was performed at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution.

[Synthesis Example 4]

In a nitrogen-purged reaction vessel, 10.20 g (31.9 mmol) of TFMB and 0.16 g (0.6 mmol) of 4,4'-DDS were placed, and 80.02 g of N,N-dimethylacetamide was added in an amount of 20% by mass of the total mass of the monomers fed (the sum of the diamine component and the carboxylic acid component), and stirred at room temperature for 30 minutes. 0.17 g (0.3 mmol) of BPADA and 9.47 g (32.2 mmol) of s-BPDA were slowly added to the solution. Stirring was carried out at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution.

[Synthesis Example 5]

In a nitrogen-purged reaction vessel, 10.93 g (51.5 mmol) of m-TD was placed, and 78.01 g of N-methyl-2-pyrrolidone was added in an amount of 22% by mass of the total mass of the monomers fed (the sum of the diamine component and the carboxylic acid component), and stirred at room temperature for 30 minutes. 1.98 g (5.1 mmol) of CpODA and 9.88 g (46.3 mmol) of CBDA were slowly added to the solution. Stirring was performed at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution.

[Synthesis Example 6]

13.55 g (38.9 mmol) of BAFL and 33.44 g (90.8 mmol) of BAPB were placed in a nitrogen-purged reaction vessel, and 395.02 g of N-methyl-2-pyrrolidone was added in an amount of 21% by mass of the total mass of the monomers fed (the sum of the diamine component and the carboxylic acid component), and stirred at room temperature for 30 minutes. 12.46 g (32.4 mmol) of CpODA and 45.55 g (97.2 mmol) of PPHT were slowly added to the solution. Stirring was carried out at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution.

[Example 1]

1.6 mg (0.017 mmol) of methylphosphonic acid and 0.56 g of N-methyl-2-pyrrolidone were added to a reaction vessel to obtain a uniform solution. 30.17 g of the polyamic acid solution obtained in Synthesis Example 1 (the total monomer amount in the polyamic acid solution is 15.8 mmol) was added to the solution, and stirred at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution. The ratio of methylphosphonic acid relative to the total amount of polyimide monomers was 0.11 mol% by calculating the feed amount.

The polyamic acid solution was applied to the glass plate of the substrate by a spin coater, and the coating was heated from 30°C to 350°C at a heating rate of 3°C/min under a nitrogen atmosphere, and heat-treated at 350°C for 10 minutes to form a polyimide film with a thickness of 10 μm on the glass plate. Regarding the peel strength, a test sample with a width of 1 inch (25.4 mm) was made from the obtained polyimide film/glass laminate and measured. Regarding the tensile test, after the obtained polyimide film/glass laminate was immersed in water, the polyimide film was peeled off from the glass plate, and cut into a specified size after drying to prepare a test sample and measure the characteristics. In the following example, a tensile test sample was also prepared and measured. Regarding the optical properties, the polyimide film was mechanically peeled off from the polyimide film/glass laminate, cut into a specified size to prepare a test sample, and measured. The same is true in the following example. For the comparative example with high peel strength and mechanically unable to be peeled off, a measurement sample was prepared in the same way as the preparation of the sample for the tensile test. The results are shown in the table.

[Example 2]

2.2 mg (0.023 mmol) of methylphosphonic acid and 0.53 g of N-methyl-2-pyrrolidone were added to a reaction vessel to obtain a uniform solution. 30.00 g of the polyamic acid solution obtained in Synthesis Example 2 (the total monomer amount in the polyamic acid solution is 24.0 mmol) was added to the solution, and stirred at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution. The ratio of methylphosphonic acid relative to the total amount of polyimide monomers was 0.10 mol% by calculating the feed amount.

The polyamic acid solution was applied to a glass plate as a substrate using a spin coater, and the coating was heated from 30°C to 350°C at a heating rate of 3°C/min in a nitrogen atmosphere, and heat-treated at 350°C for 10 minutes to form a polyimide film with a thickness of 10 μm on the glass plate. The obtained film was peeled off from the glass plate, and various properties were measured.

[Example 3]

1.6 mg (0.017 mmol) of methylphosphonic acid and 0.53 g of N-methyl-2-pyrrolidone were added to a reaction vessel to obtain a uniform solution. 30.02 g of the polyamic acid solution obtained in Synthesis Example 3 (the total monomer amount in the polyamic acid solution is 16.7 mmol) was added to the solution, and stirred at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution. The ratio of methylphosphonic acid relative to the total amount of polyimide monomers was 0.10 mol% by calculating the feed amount.

The polyamic acid solution was applied to a glass plate as a substrate using a spin coater, and the coating was heated from 30°C to 350°C at a heating rate of 3°C/min in a nitrogen atmosphere, and heat-treated at 350°C for 10 minutes to form a polyimide film with a thickness of 10 μm on the glass plate. The obtained film was peeled off from the glass plate, and various properties were measured.

[Example 4]

29.99 g of the polyamic acid solution obtained in Synthesis Example 4 (the total monomer amount in the polyamic acid solution is 20.8 mmol) was added to 1.9 mg (0.020 mmol) of methylphosphonic acid, and stirred at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution. The ratio of methylphosphonic acid to the total amount of polyimide monomers was 0.10 mol% calculated from the feed amount.

The polyamic acid solution was applied to a glass plate of a substrate using a spin coater, and the coating was heated from 30°C to 70°C at a heating rate of 2.5°C/min in a nitrogen atmosphere, and kept at 70°C for 20 minutes, then heated from 70°C to 120°C at a heating rate of 2.5°C/min, and kept at 120°C for 20 minutes, then heated from 120°C to 300°C at a heating rate of 4.6°C/min, and heat-treated at 300°C for 5 minutes to form a polyimide film with a thickness of 10 μm on the glass plate. The obtained film was peeled off from the glass plate, and various properties were measured.

[Example 5]

30.03 g of the polyamic acid solution obtained in Synthesis Example 5 (the total monomer amount in the polyamic acid solution is 30.9 mmol) was added to 3.1 mg (0.032 mmol) of methylphosphonic acid, and stirred at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution. The ratio of methylphosphonic acid to the total amount of polyimide monomers was 0.10 mol% calculated from the feed amount.

The polyamic acid solution was applied to a glass plate of a substrate using a spin coater, and the coating was heated from 30°C to 80°C at a heating rate of 3°C/min in a nitrogen atmosphere, and maintained at 80°C for 30 minutes, and then heated from 80°C to 260°C at a heating rate of 3°C/min, and heat-treated at 260°C for 10 minutes to form a polyimide film with a thickness of 10 μm on the glass plate. The obtained film was peeled off from the glass plate, and various properties were measured.

[Example 6]

1.9 mg (0.020 mmol) of methylphosphonic acid and 0.60 g of N-methyl-2-pyrrolidone were added to a reaction vessel to obtain a uniform solution. 40.02 g of the polyamic acid solution obtained in Synthesis Example 6 (the total monomer amount in the polyamic acid solution is 20.8 mmol) was added to the solution, and stirred at room temperature for 12 hours to obtain a uniform and viscous polyimide precursor solution. The ratio of methylphosphonic acid relative to the total amount of polyimide monomers was 0.10 mol% by calculating the feed amount.

The polyamic acid solution was applied to a glass plate as a substrate using a spin coater, and the coating was heated from 30°C to 310°C at a heating rate of 5°C/min in a nitrogen atmosphere, and heat-treated at 310°C for 20 minutes to form a polyimide film with a thickness of 10 μm on the glass plate. The obtained film was peeled off from the glass plate, and various properties were measured.

[Comparative Example 1]

A polyimide film was formed and various properties were measured in the same manner as in Example 6 except that the polyamic acid solution obtained in Synthesis Example 6 was used as it is. However, in the peel test, although a test sample was attempted to be prepared, the adhesion between the glass plate and the polyimide film was so great that a gripping portion of the film could not be prepared and measurement could not be performed.

[Comparative Example 2]

Methylphosphonic acid 10mg (0.10 mmol) and N-methyl-2-pyrrolidone 10.02g are added in the reaction vessel, obtain uniform solution.In this solution 14.5mg, add the polyamic acid solution 30.00g (total monomer amount in the polyamic acid solution is 15.6 mmol) obtained in synthesis example 6, at room temperature stir 12 hours, obtain uniform and viscous polyimide precursor solution.Calculate by charging capacity, the ratio of the methylphosphonic acid relative to the total amount of polyimide monomers is 0.001mol%.Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Example 7]

Methylphosphonic acid 10mg (0.10 mmol) and N-methyl-2-pyrrolidone 10.01g are added in the reaction vessel, obtain uniform solution.In this solution 149.9mg, add the polyamic acid solution 29.98g (total monomer amount in the polyamic acid solution is 15.5 mmoles) obtained in synthesis example 6, at room temperature stir 12 hours, obtain uniform and viscous polyimide precursor solution.Calculate by charging capacity, the ratio of the methylphosphonic acid relative to the total amount of polyimide monomers is 0.01mol%.Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Example 8]

Methylphosphonic acid 49.9mg (0.52 mmol) and N-methyl-2-pyrrolidone 5.07g are added in the reaction vessel, obtain uniform solution.In this solution 50.2mg, add the polyamic acid solution 20.01g (total monomer amount in the polyamic acid solution is 10.4 mmol) obtained in synthesis example 6, at room temperature stir 12 hours, obtain uniform and viscous polyimide precursor solution.Calculate by charging capacity, the ratio of the methylphosphonic acid relative to the polyimide monomer total amount is 0.05mol%.Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Example 9]

Methylphosphonic acid 7.7mg (0.080 mmol) and N-methyl-2-pyrrolidone 0.52g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 30.14g (total monomer amount in the polyamic acid solution is 15.6 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by feeding amount, the ratio of the methylphosphonic acid relative to the total amount of polyimide monomers is 0.5mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Example 10]

Methylphosphonic acid 12.0mg (0.13 mmol) and N-methyl-2-pyrrolidone 0.50g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 20.16g (total monomer amount in the polyamic acid solution is 10.5 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by charging capacity, the ratio of the methylphosphonic acid relative to the total amount of polyimide monomers is 1.2mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Comparative Example 3]

Methylphosphonic acid 49.8mg (0.52 mmol) and N-methyl-2-pyrrolidone 0.50g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 20.03g (total monomer amount in the polyamic acid solution is 10.4 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by charging capacity, the ratio of the methylphosphonic acid relative to the total amount of polyimide monomers is 5.0mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the measurement of various characteristics. However, the peel strength of glass plate and polyimide film is too small, and it is naturally peeled off in the stripping test sample making.

[Example 11]

Phosphoric acid 2.4mg (0.021 mmol) and N-methyl-2-pyrrolidone 0.60g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 43.29g (total monomer amount in the polyamic acid solution is 22.4 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by feeding amount, the ratio of phosphoric acid relative to the total amount of polyimide monomer is 0.09mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the measurement of various characteristics.

[Example 12]

Phosphoric acid 9.2mg (0.080 mmol) and N-methyl-2-pyrrolidone 0.51g are added to the reaction vessel to obtain a uniform solution. In this solution, the polyamic acid solution 30.00g (total monomer amount in the polyamic acid solution is 15.6 mmol) obtained in the synthesis example 6 is added, stirred at room temperature for 12 hours, and a uniform and viscous polyimide precursor solution is obtained. Calculated by the feed amount, the ratio of phosphoric acid relative to the total amount of polyimide monomers is 0.51mol%. Using this polyamic acid solution, polyimide film is formed in the same manner as in Example 6, and various characteristics are measured.

[Example 13]

Phosphoric acid 12.2mg (0.106 mmol) and N-methyl-2-pyrrolidone 0.53g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 19.99g (total monomer amount in the polyamic acid solution is 10.4 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by feeding amount, the ratio of phosphoric acid relative to the total amount of polyimide monomer is 1.0mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the measurement of various characteristics.

[Example 14]

Tributyl phosphate 4.5mg (0.017 mmol) and N-methyl-2-pyrrolidone 0.60g are added to the reaction vessel to obtain a uniform solution. In this solution, the polyamic acid solution 35.96g (total monomer amount in the polyamic acid solution is 18.6 mmol) obtained in the synthesis example 6 is added, stirred at room temperature for 12 hours, and a uniform and viscous polyimide precursor solution is obtained. Calculated by the feed amount, the ratio of tributyl phosphate relative to the total amount of polyimide monomers is 0.09mol%. Use this polyamic acid solution, otherwise form a polyimide film in the same manner as in Example 6, and carry out the measurement of various characteristics.

[Example 15]

Tributyl phosphate 32.7mg (0.123 mmol) and N-methyl-2-pyrrolidone 0.50g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 20.06g (total monomer amount in the polyamic acid solution is 10.4 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by feeding amount, the ratio of tributyl phosphate relative to the total amount of polyimide monomer is 1.2mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the measurement of various characteristics.

[Example 16]

Diphenylphosphinic acid 4.4mg (0.0201 mmol) and N-methyl-2-pyrrolidone 0.61g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 40.11g (total monomer amount in the polyamic acid solution is 20.8 mmol) obtained in the synthesis example 6, stir at room temperature for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by charging capacity, the ratio of diphenylphosphinic acid relative to the total amount of polyimide monomers is 0.10mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Comparative Example 4]

Diethyl methylphosphonate 3.5mg (0.023 mmol) and N-methyl-2-pyrrolidone 0.61g are added in the reaction vessel to obtain uniform solution. In this solution, add the polyamic acid solution 40.06g (total monomer amount in the polyamic acid solution is 20.8 mmol) obtained in the synthesis example 6, at room temperature stir for 12 hours, obtain uniform and viscous polyimide precursor solution. Calculated by feeding amount, the ratio of diethyl methylphosphonate relative to the total amount of polyimide monomers is 0.11mol%. Use this polyamic acid solution, otherwise form polyimide film in the same manner as Example 6, carry out the mensuration of various characteristics.

[Comparative Example 5]

Tributylphosphine oxide 4.6mg (0.021 mmol) and N-methyl-2-pyrrolidone 0.79g are added to the reaction vessel to obtain a uniform solution. 39.97g of the polyamic acid solution obtained in Synthesis Example 6 (the total monomer amount in the polyamic acid solution is 20.7 mmol) is added to the solution, stirred at room temperature for 12 hours, and a uniform and viscous polyimide precursor solution is obtained. Calculated by the feed amount, the ratio of tributylphosphine oxide relative to the total amount of polyimide monomers is 0.10mol%. Using this polyamic acid solution, a polyimide film is formed in the same manner as in Example 6, and various characteristics are measured.

[Comparative Examples 6 to 9]

A polyimide film was formed in the same manner as in Example 6 except that the polyamic acid solutions obtained in Synthesis Examples 1 to 3 and 5 were used as they were, and various properties were measured.

The compositions of Examples and Comparative Examples and the measurement results of b ^* , peeling characteristics, and 400 nm transmittance of the obtained films are shown in Tables 3 to 7. The film properties of Examples were further measured and the results are shown in Tables 8 to 10.

[Table 3]

The unit N/in. is N/25.4mm.

[Table 4]

*) Large: The peel strength is too large and cannot be made into a test sample. Small: The peel strength is too small and it peels naturally during the preparation of the test sample.

[Table 5]

[Table 6]

[Table 7]

[Table 8]

Physical properties Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Tg(TMA)/℃ 324 333 323 304 325 300 Td 1%/℃ - - - - - 413 400nm Transmittance % 85.9 84.3 81.9 60.5 88.7 85.8 Total transmittance/%T(380-780nm) 90.6 89.6 89.6 85.5 90.1 88.5

In the table, - means not determined.

[Table 9]

Physical properties Example 7 Example 8 Example 9 Example 10 Tg(TMA)/℃ 301 299 302 311 Td 1%/℃ - - - - 400nm Transmittance % 86.4 87.0 86.7 87.1 Total transmittance/%T(380-780nm) 89.6 89.7 89.3 89.7

[Table 10]

Physical properties Embodiment 11 Example 12 Example 13 Embodiment 14 Embodiment 15 Example 16 Tg(TMA)/℃ 302 - - 301 - 300 Td 1%/℃ 415 - - 419 407 415 400nm Transmittance % 85.6 86.4 85.7 85.7 85.1 85.8 Total transmittance/%T(380-780nm) 88.5 89.4 89.4 88.5 - 88.5

Industrial Applicability

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

Claims (14)

1. A polyimide precursor composition comprising a polyimide precursor and a polyimide precursor, characterized by comprising:

a polyimide precursor;

A phosphorus compound in an amount exceeding 0.001 mol% and less than 5 mol% with respect to the total monomer units of the polyimide precursor, the phosphorus compound being selected from the group consisting of phosphoric acid, a monoalkyl phosphonate having 2 OH and 1 alkyl groups bonded to a phosphorus atom, a dialkyl phosphinate having 1 OH and 2 alkyl groups bonded to a phosphorus atom, an alkyl monoalkyl phosphinate having 1 OH and 1 alkoxy and 1 alkyl groups bonded to a phosphorus atom, a dialkyl monoalkyl phosphinate having 2 alkoxy groups having 4 or more carbon atoms and 1 alkyl group bonded to a phosphorus atom, and a monoalkyl dialkyl phosphinate having 1 alkoxy group having 4 or more carbon atoms and 2 alkyl groups bonded to a phosphorus atom; and

The solvent is used for the preparation of the aqueous solution,

Wherein the polyimide precursor composition satisfies the following condition (A),

(A) The polyimide precursor is not a polyimide precursor obtained from only 3,3', 4' -biphenyltetracarboxylic dianhydride and p-phenylenediamine.

2. The composition according to claim 1, wherein the content of the phosphorus compound is 0.01 mol% or more relative to the total monomer units of the polyimide precursor.

3. The composition of claim 1, wherein the phosphorus compound has a molecular weight of less than 400.

4. The composition of claim 1, wherein the polyimide precursor comprises a repeating unit selected from the group consisting of a structure represented by the following general formula (I) and a structure in which at least 1 amide structure in the general formula (I) is imidized,

[ Chemical 1]

In the general formula I, X ₁ is a 4-valent aliphatic group or aromatic group, Y ₁ is a 2-valent aliphatic group or aromatic group, and R ₁ and R ₂ are, independently of each other, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkylsilyl group having 3 to 9 carbon atoms.

5. The composition according to claim 4, wherein X ₁ is a 4-valent group having an alicyclic structure and Y ₁ is a 2-valent group having an alicyclic structure, and the content of the repeating unit represented by general formula (I) is 50 mol% or less based on the total repeating units.

6. The composition of claim 4, wherein X ₁ in formula (I) is a 4-valent group having an aromatic ring and Y ₁ is a 2-valent group having an aromatic ring.

7. The composition of claim 4, wherein X ₁ in the general formula (I) is a 4-valent group having an alicyclic structure, and Y ₁ is a 2-valent group having an aromatic ring.

8. The composition of claim 4, wherein X ₁ in formula (I) is a 4-valent group having an aromatic ring and Y ₁ is a 2-valent group having an alicyclic structure.

9. The composition according to claim 4, wherein X ₁ in the general formula (I) is a repeating unit having a 4-valent group having an alicyclic structure, wherein X ₁ is a 4-valent group having an alicyclic structure and Y ₁ is a 2-valent group having an alicyclic structure, and the content of the repeating unit represented by the general formula (I) is 50 mol% or less with respect to the total repeating units, in an amount exceeding 60% of the total repeating units.

10. A method of manufacturing a flexible electronic device, comprising:

(a) A step of applying the polyimide precursor composition according to any one of claims 1 to 9 to a substrate;

(b) A step of producing a laminate in which a polyimide film is laminated on the base material by heating the polyimide precursor on the base material;

(c) Forming at least 1 layer selected from a conductor layer and a semiconductor layer on the polyimide film of the laminate; and

(D) And peeling the base material from the polyimide film by an external force.

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

12. The method according to claim 10 or 11, wherein laser irradiation is not performed in the step of peeling the substrate from the polyimide film.

13. A method for reducing peel strength of a laminate, which is a method for reducing peel strength between a polyimide film and a substrate of a laminate having the substrate and the polyimide film formed on the substrate, characterized by comprising the steps of,

The polyimide precursor composition for forming the polyimide film contains a phosphorus compound so as to be the polyimide precursor according to any one of claims 1 to 9.

14. The method of claim 13, wherein the substrate is a glass sheet.