KR102147082B1 - Polyimide precursor, resin composition, resin film and method of producing resin film - Google Patents

Abstract

로 나타내는 구조를 포함한다.(Problem) A polyimide precursor, a polyimide resin film and a method for producing the same, which have low residual stress, little warpage, little yellowness (YI value) in a high temperature region, and high elongation are provided.
(Solution) As a resin composition for a substrate of a low-temperature polysilicon TFT element containing a polyimide precursor obtained by polymerizing a diamine component and an acid dianhydride component, and a solvent, the polyimide precursor,
(a) the following general formula (1):

It includes a structure represented by

Description

A polyimide precursor, a resin composition, a resin film, and a manufacturing method thereof TECHNICAL FIELD [0002] POLYIMIDE PRECURSOR, RESIN COMPOSITION, RESIN FILM AND METHOD OF PRODUCING RESIN FILM}

The present invention relates to, for example, a polyimide precursor, a resin composition, a resin film, and a manufacturing method used for manufacturing a substrate for a flexible device.

In general, for applications requiring high heat resistance, a polyimide resin film is used as a resin film. A general polyimide resin is a high heat-resistant resin prepared by preparing a polyimide precursor by solution polymerization of an aromatic carboxylic acid dianhydride and an aromatic diamine, and then thermally imidating this at a high temperature or chemically imidating it using a catalyst. to be.

Polyimide resin is an insoluble and insoluble super heat-resistant resin, and has excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature resistance, and chemical resistance. For this reason, polyimide resins are used in a wide range of fields containing electronic materials. Examples of application of the polyimide resin in the field of electronic materials include, for example, an insulating coating agent, an insulating film, a semiconductor protective film, and a TFT-LCD electrode protective film. In recent years, instead of a glass substrate conventionally used in the field of display materials, adoption as a colorless transparent flexible substrate utilizing its lightness and flexibility has been studied.

In the case of manufacturing a polyimide resin film as a flexible substrate, a polyimide resin film is obtained by applying a composition containing a polyimide precursor on a suitable support to form a coating film, followed by heat treatment and imidation. As the support, for example, glass, silicon, silicon nitride, silicon oxide, and metal are used. When manufacturing a laminate having a polyimide film on such a support, a heat treatment at a high temperature of 250° C. or higher is required for drying and imidization of the polyimide precursor. This heat treatment generates residual stress in the laminate, causing serious problems such as warping and peeling. This is because the linear thermal expansion coefficient of polyimide is larger than that of the material constituting the support.

As a polyimide material having a small coefficient of thermal expansion, a polyimide formed of 3,3',4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine is best known. Although depending on the film thickness and production conditions, it has been reported that this polyimide film exhibits a very low coefficient of linear thermal expansion (Non-Patent Document 1).

Further, it has been reported that a polyimide having an ester structure in a molecular chain exhibits a low coefficient of linear thermal expansion because it has moderate linearity and rigidity (Patent Document 1).

However, since general polyimide resins, including the polyimide described in the above documents, are colored brown or yellow due to a high aromatic ring density, the light transmittance in the visible region is low, and thus colorless transparency is required. It is difficult to use in the field. For example, the polyimide of Non-Patent Document 1 obtained from 3,3',4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine has a yellowness in a film thickness of 10 µm (YI Value) is as high as 40 or more, and is insufficient in terms of colorless transparency.

As for the yellowness of a film, it is known that, for example, a polyimide using a monomer having a fluorine atom exhibits a very low yellowness (Patent Document 2).

Further, a polyimide precursor having both low yellowness and low Rth is disclosed (Patent Document 3).

Japanese Patent No. 4627297 Specification Japanese Patent Publication No. 2010-538103 International Publication No. 2014/148441

Latest Polyimide Japan Polyimide Research Group N·T·S

By the way, in order to apply the polyimide resin as a colorless transparent flexible substrate, in addition to transparency, it is required that the residual stress with the substrate is small, the glass transition temperature is high, and the Rth (retardation) is low.

Conventionally, since the device type of a TFT manufactured for driving a display display was amorphous silicon or IGZO, the process temperature was 350°C or less.

On the other hand, in recent years, with the device type of the TFT being low-temperature polysilicon (hereinafter referred to as LTPS), the process temperature becomes 400°C or higher, and a film exhibiting the above physical properties is desired even after such a high-temperature thermal history. Has become.

However, the physical properties of known transparent polyimide are not sufficient for use as a heat-resistant colorless transparent substrate for a display.

In addition, as a result of confirmation by the present inventors, the polyimide resin described in Patent Document 1 exhibited a low coefficient of linear thermal expansion, but in addition to having a large yellowness (YI value) of the polyimide resin film after peeling, there is a problem of high residual stress. I could see that there is.

Regarding the yellowness, in the polyimide films described in Patent Documents 2 and 3, a low yellowness is exhibited in a temperature range of about 300°C, but after a high-temperature thermal history of 400°C or higher, the yellowness (YI value) is significantly deteriorated. I could see it.

The present invention has been made in view of the above-described problems. Accordingly, the present invention has a small yellowness (YI value) after high-temperature thermal history, which is preferably used when the device type of the TFT is LTPS, the residual stress with the glass substrate is small, the glass transition temperature is high, and Rth ( It aims at providing a polyimide resin film with low retardation), its manufacturing method, and a laminated body.

In order to solve the above problems, the inventors of the present invention have conducted extensive research. As a result, it was found that the polyimide resin film obtained by curing a resin composition containing a polyimide precursor having a specific structure has a small yellowness (YI value) in a high temperature region and a small residual stress with a substrate. In addition, it was found that the laminate containing the polyimide film of a specific structure and the LTPS layer had no warpage when used as an organic EL device, the lighting test was good, and the ash after laser peeling was small, and based on these findings, the present invention Came to achieve.

That is, the present invention is as follows.

[One]

A resin composition for a substrate of a low-temperature polysilicon TFT element containing a polyimide precursor obtained by polymerizing a diamine component and an acid dianhydride component, and a solvent,

The polyimide precursor,

(a) the following general formula (1):

[Formula 1]

A resin composition for a substrate of a low-temperature polysilicon TFT device, comprising a structure represented by.

[2]

The polyimide precursor is the following general formula (2):

[Formula 2]

A resin composition for a substrate of a low-temperature polysilicon TFT element according to [1], containing the structure represented by.

[3]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [1] or [2], wherein the weight average molecular weight of the polyimide precursor is 40,000 or more and 300,000 or less.

[4]

When the total weight of the solid content contained in the resin composition is 100% by mass, the low-temperature poly according to any one of [1] to [3], wherein the amount of molecules having a molecular weight less than 1,000 contained in the solid content is less than 5% by mass. Resin composition for a substrate of a silicon TFT element.

[5]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [4], wherein the amount of the molecule contained in the solid content and having a molecular weight of less than 1,000 is 1% by mass or less.

[6]

The polyimide precursor, when the total mass of the diamine component and the acid dianhydride component is 100% by mass,

Equation (3) below:

[Formula 3]

(In the formula, plural R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200)

The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of [1] to [5], wherein the content of the silicone diamine component containing the structure represented by is less than 6% by mass.

[7]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [6], wherein the content of the silicone diamine component is 5.9% by mass or less.

[8]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [7], wherein the content of the silicone diamine component is 3% by mass or less.

[9]

The polyimide precursor is contained in the polyimide precursor when the total number of moles of the diamine component is 100 mol%, the following general formula (4):

[Formula 4]

(In the formula, R ₁ , R ₂ , and R ₃ each independently represent a monovalent organic group having 1 to 20 carbon atoms. n represents 0 or 1. And a, b and c are integers of 0 to 4)

The resin composition for a substrate of a low-temperature polysilicon TFT element according to any one of [1] to [8], wherein the amount of diamine represented by is 48 mol% or less.

[10]

The resin composition for a substrate of a low-temperature polysilicon TFT element according to [9], wherein the amount of diamine contained in the polyimide precursor represented by the general formula (4) is less than 1 mol%.

[11]

The resin composition for a substrate of a low-temperature polysilicon TFT element according to [10], wherein the amount of diamine contained in the polyimide precursor represented by the general formula (4) is 0.9 mol% or less.

[12]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [9], wherein the polyimide precursor contains 4-aminophenyl-4-aminobenzoate as a diamine component represented by the general formula (4).

[13]

The polyimide precursor is in any one of [1] to [12], wherein the content of the 4-aminophenyl-4-aminobenzoate is 48 mol% or less when the total number of moles of the diamine component is 100 mol%. The resin composition for a substrate of the low-temperature polysilicon TFT element described above.

[14]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [13], wherein the polyimide precursor has a content of the 4-aminophenyl-4-aminobenzoate of less than 1 mol%.

[15]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [14], wherein the polyimide precursor has a content of the 4-aminophenyl-4-aminobenzoate of less than 0.9 mol%.

[16]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to any one of [1] to [15], wherein the polyimide precursor contains diaminodiphenylsulfone as the diamine component.

[17]

The polyimide precursor is a resin composition for a substrate of a low-temperature polysilicon TFT device according to [16], wherein the diaminodiphenyl sulfone content is 90 mol% or more when the total number of moles of the diamine component is 100 mol%. .

[18]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to any one of [1] to [17], wherein the polyimide precursor contains pyromellitic dianhydride as the acid dianhydride component.

[19]

The polyimide precursor is used for a substrate of a low-temperature polysilicon TFT device according to [18], wherein the content of the pyromellitic dianhydride is 90 mol% or more when the total number of moles of the acid dianhydride component is 100 mol%. Resin composition.

[20]

The resin for a substrate of a low-temperature polysilicon TFT device according to any one of [1] to [19], wherein the yellowness of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 20 or less in a film thickness of 10 µm. Composition.

[21]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [20], wherein the yellowness of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 13 or less in a film thickness of 10 µm.

[22]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to any one of [1] to [21], wherein the glass transition temperature of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 360°C or higher.

[23]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [22], wherein the glass transition temperature of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 470°C or higher.

[24]

For a substrate of a low-temperature polysilicon TFT device according to any one of [1] to [23], wherein the retardation of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 1000 nm or less in a film thickness of 10 µm. Resin composition.

[25]

The resin composition for a substrate of a low-temperature polysilicon TFT device according to [24], wherein the retardation of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 140 nm or less in a film thickness of 10 µm.

[26]

A step of applying the resin composition according to any one of [1] to [25] on the surface of the support, and

The step of forming a polyimide resin film from the resin composition, and

Step of peeling the polyimide resin film from the support

It characterized in that it comprises a, the manufacturing method of a resin film.

[27]

Prior to the step of peeling the polyimide resin film from the support, a step of irradiating a laser from the support side is performed.

[28]

A method for producing a display, including a method for producing a resin film by the method according to claim [26] or [27].

[29]

A step of applying the resin composition according to any one of [1] to [25] on the surface of the support, and

The step of forming a polyimide resin film from the resin composition, and

Step of forming a low-temperature polysilicon TFT on the polyimide resin film

A method for producing a laminate comprising a.

[30]

The method for producing a laminate according to [29], further comprising a step of peeling the polyimide resin film from the support.

[31]

A method for producing a flexible device, including the method for producing a laminate according to [29] or [30].

[32]

The following general formula (5):

[Formula 5]

A laminate comprising a polyimide layer containing a polyimide represented by and a low-temperature polysilicon TFT layer.

[33]

The laminate according to [32], wherein the amount of molecules with a molecular weight of less than 1,000 contained in the polyimide layer is less than 5% by mass.

[34]

A polyimide film characterized by having a yellowness of 20 or less in a film thickness of 10 µm when heated at 430°C, a residual stress of 25 MPa or less, and an elongation of 15% or more.

The polyimide film obtained from the resin composition according to the present invention has a small yellowness (YI value) in a high temperature region, a small residual stress with a substrate, a high glass transition temperature, and a low Rth (retardation).

Moreover, the laminated body containing the polyimide film and the low-temperature polysilicon TFT obtained from the resin composition according to the present invention has little warpage, low haze, and good heat cycle test results.

1 is a diagram showing an organic EL structure in which the present invention is applied to an organic EL substrate.

Hereinafter, exemplary embodiments of the present invention (hereinafter, abbreviated as "embodiment") will be described in detail. In addition, the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist. In addition, unless otherwise specified, the characteristic values described in the present disclosure are intended to be values measured by the method described in the [Example] section or a method equivalent to this is understood by those skilled in the art.

<Resin composition>

The resin composition provided by one aspect of the present invention contains (a) a polyimide precursor, and (b) an organic solvent.

Hereinafter, each component will be described in order.

[Polyimide Precursor]

The polyimide precursor in this embodiment,

(a) the following general formula (1):

[Formula 6]

It is a polyimide precursor represented by.

As the acid dianhydride used in the general formula (1) according to the present embodiment, pyromellitic dianhydride (hereinafter, also described as PMDA) can be exemplified.

As the diamine used in the general formula (1) according to the present embodiment, 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone can be illustrated.

Among these, from the viewpoint of residual stress, YI, glass transition temperature, retardation Rth, elongation, and haze of the obtained polyimide film, a structure using 4,4'-diaminodiphenylsulfone represented by the following general formula (2) It is more preferable.

[Formula 7]

The weight average molecular weight (Mw) of the polyimide precursor in this embodiment is preferably 10,000 to 300,000, and particularly preferably 40,000 to 300,000. When the weight average molecular weight is 40,000 or more, in particular, mechanical properties such as elongation and breaking strength are excellent, residual stress is low, and YI is low. When the weight average molecular weight is less than 300,000, it becomes easy to control the weight average molecular weight at the time of synthesis of the polyamic acid, a resin composition having an appropriate viscosity can be obtained, and the coating property of the resin composition becomes good. In the present disclosure, the weight average molecular weight is a value calculated as a standard polystyrene conversion value using gel permeation chromatography (hereinafter, also referred to as GPC).

When the total weight of the solid content contained in the resin composition of the present embodiment is 100% by mass, the smaller the content of molecules having a molecular weight of less than 1,000, the more preferable. Specifically, it is preferably less than 5% by mass, preferably 4% by mass or less, preferably 3% by mass or less, preferably 2% by mass or less, and preferably 1% by mass or less, based on the total weight of the solid content. , 0.5% by mass or less is preferable, 0.1% by mass or less is preferable, 0.05% by mass or less is preferable, and 0.02% by mass or less is preferable.

Such a composition is excellent in viscosity stability and varnish coatability. Moreover, the polyimide film obtained from such a composition has a low residual stress, a small YI, a high glass transition temperature (Tg), a low retardation Rth, and a high elongation, and is preferable. Moreover, the laminated body containing such a polyimide film and a low-temperature polysilicon TFT has little warpage, a low haze, and a heat cycle test result is good. The content of a molecule having a molecular weight of less than 1,000 can be calculated from the peak area obtained by performing GPC measurement of the resin composition.

In addition to pyromellitic dianhydride, other acid dianhydrides can be used for the polyimide precursor in the present embodiment as long as elongation, strength, stress, and yellowness are not impaired.

As such an acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1 ,2dicarboxylic anhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3, 3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride , 2,2',3,3'-biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2 ,2-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1 ,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, p-phenylenebis( Trimellitate anhydride), thio-4,4'-diphthalic dianhydride, sulfonyl-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4) -Dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, bis[3-(3,4-di Carboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl] Propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis( 3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetra Carboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, etc. Can be illustrated.

The content of the other acid dianhydrides in the total acid dianhydride is preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 0 mol%.

The content of pyromellitic dianhydride in all acid dianhydrides is preferably 90 mol% or more, preferably 95 mol% or more, preferably 98 mol% or more, preferably 99 mol% or more, and 99.5 mol% or more This is desirable. The larger the amount of pyromellitic dianhydride in the total acid dianhydride is, the more preferable it is from the viewpoints of YI, glass transition temperature Tg, and elongation.

In the polyimide precursor in this embodiment, in addition to 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone, in the range that does not impair elongation, strength, stress, yellowness, etc. Other diamines can be used.

As other diamines, for example, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 3,3' -Diaminodiphenylsulfide, 4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3, 4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane , 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, bis[4-(4- Aminophenoxy)phenyl]sulfone, 4,4-bis(4-aminophenoxy)biphenyl, 4,4-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl ]Ether, bis[4-(3-aminophenoxy)phenyl]ether, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 9,10-bis( 4-aminophenyl)anthracene, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy) ) Phenyl) propane, 2,2-bis[4-(4-aminophenoxy)phenyl)hexafluoropropane, 1,4-bis(3-aminopropyldimethylsilyl)benzene, and the like, selected from these It is preferable to use at least one of which is used.

The content of the other diamines in all diamines is preferably 20 mol% or less, more preferably 10 mol% or less, and particularly preferably 0 mol%.

The content of diaminodiphenylsulfone in all diamines is preferably 90 mol% or more, preferably 95 mol% or more, preferably 98 mol% or more, preferably 99 mol% or more, and 99.5 mol% or more. Do. The larger the amount of diaminodiphenylsulfone is, the more preferable it is in terms of residual stress, YI, glass transition temperature Tg, retardation Rth, and elongation. As the diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone is preferable.

In the polyimide precursor, when the total number of moles of the diamine component is 100 mol%, the amount of the diamine represented by the following general formula (4) contained in the polyimide precursor is preferably 48 mol% or less.

[Formula 8]

(In the formula, R ₁ , R ₂ , and R ₃ each independently represent a monovalent organic group having 1 to 20 carbon atoms. n represents 0 or 1. And a, b and c are integers of 0 to 4.)

As the diamine represented by the general formula (4), for example, when n is 0, 4-aminophenyl-4-aminobenzoate (APAB), 2-methyl-4-aminophenyl-4-aminobenzoate ( ATAB), 4-aminophenyl-3-aminobenzoate (4,3-APAB) and the like can be illustrated. When n is 1, [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate etc. can be illustrated.

In particular, the polyimide precursor is a diamine component represented by the general formula (4), and the content of 4-aminophenyl-4-aminobenzoate contained in the polyimide precursor when the total number of moles of the diamine component is 100 mol% It is preferable that it is 48 mol% or less. The effect that YI is small, Tg is high, retardation is low, and elongation is high is obtained. 4-aminophenyl-4-aminobenzoate may or may not be contained.

The smaller the amount of the diamine represented by the general formula (4) is, the more preferable it is from the viewpoints of YI, glass transition temperature Tg, retardation Rth, and elongation.

The amount of the diamine represented by the general formula (4) contained in the polyimide precursor is preferably 30 mol% or less, preferably 20 mol% or less, preferably 10 mol% or less, and 5 mol% or less.

Further, the amount of diamine represented by the general formula (4), particularly, for example, 4-aminophenyl-4-aminobenzoate, is preferably less than 1 mol%, preferably 0.9 mol% or less, and 0.8 mol% or less. And 0.6 mol% or less is preferable, 0.4 mol% or less is preferable, 0.2 mol% or less is preferable, and 0.1 mol% or less is preferable.

The polyimide precursor,

When the total mass of the diamine component and the acid dianhydride component is 100% by mass,

Equation (3) below:

[Formula 9]

(In the formula, plural R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200)

It is preferable that the content of the silicone diamine component containing the structure represented by is less than 6% by mass.

The smaller the number of silicon diamine components containing the structure represented by the above formula (3), the smaller YI, the larger the glass transition temperature Tg, and the smaller the retardation Rth, which is preferable. The content of the silicone diamine component containing the structure represented by the above formula (3) is preferably 5.9 mass% or less, 5.5 mass% or less, 5.0 mass% or less, 4.0 mass% or less, and 3.0 mass% or less, 2.0 mass% or less, 1.0 mass% or less, 0.5 mass% or less, 0.4 mass% or less, 0.3 mass% or less, 0.2 mass% or less, 0.1 mass% or less, 0.08 mass% or less, 0.06 mass It is less than or equal to 0.04 mass%, and less than or equal to 0.02 mass%.

The polyimide precursor in the embodiment may be a polyamideimide precursor by using a dicarboxylic acid in addition to the tetracarboxylic dianhydride described above within a range that does not impair its performance. By using such a precursor, various performances such as improvement in mechanical elongation, improvement in glass transition temperature, and reduction in yellowness in the resulting film can be adjusted. As such dicarboxylic acid, dicarboxylic acid and alicyclic dicarboxylic acid having an aromatic ring can be mentioned. In particular, it is preferably at least one compound selected from the group consisting of an aromatic dicarboxylic acid having 8 to 36 carbon atoms and an alicyclic dicarboxylic acid having 6 to 34 carbon atoms. The number of carbons referred to herein includes the number of carbons contained in the carboxyl group.

Among these, dicarboxylic acids having an aromatic ring are preferred.

Specifically, for example, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid, 3,4'-biphenyldicarboxylic acid, 3,3'-biphenyldicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbisbenzoic acid, 3, 4'-sulfonylbisbenzoic acid, 3,3'-sulfonylbisbenzoic acid, 4,4'-oxybisbenzoic acid, 3,4'-oxybisbenzoic acid, 3,3'-oxybisbenzoic acid, 2,2-bis (4-carboxyphenyl)propane, 2,2-bis(3-carboxyphenyl)propane, 2,2'-dimethyl-4,4'-biphenyldicarboxylic acid, 3,3'-dimethyl-4,4 '-Biphenyldicarboxylic acid, 2,2'-dimethyl-3,3'-biphenyldicarboxylic acid, 9,9-bis(4-(4-carboxyphenoxy)phenyl)fluorene, 9, 9-bis(4-(3-carboxyphenoxy)phenyl)fluorene, 4,4'-bis(4-carboxyphenoxy)biphenyl, 4,4'-bis(3-carboxyphenoxy)biphenyl, 3,4'-bis(4-carboxyphenoxy)biphenyl, 3,4'-bis(3-carboxyphenoxy)biphenyl, 3,3'-bis(4-carboxyphenoxy)biphenyl, 3, 3'-bis(3-carboxyphenoxy)biphenyl, 4,4'-bis(4-carboxyphenoxy)-p-terphenyl, 4,4'-bis(4-carboxyphenoxy)-m-ter Phenyl, 3,4'-bis(4-carboxyphenoxy)-p-terphenyl, 3,3'-bis(4-carboxyphenoxy)-p-terphenyl, 3,4'-bis(4-carboxy) Phenoxy)-m-terphenyl, 3,3'-bis(4-carboxyphenoxy)-m-terphenyl, 4,4'-bis(3-carboxyphenoxy)-p-terphenyl, 4,4 '-Bis(3-carboxyphenoxy)-m-terphenyl, 3,4'-bis(3-carboxyphenoxy)-p-terphenyl, 3,3'-bis(3-carboxyphenoxy)-p -Terphenyl, 3,4'-bis(3-carboxyphenoxy)-m-terphenyl, 3,3'-bis(3-carboxyphenoxy)-m-terphenyl, 1,1-cyclobutanedicar Acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 1,3-phenylene 2 acetic acid, 1,4- Phenylene diacetic acid, etc.; And 5-aminoisophthalic acid derivatives described in the pamphlet of International Publication No. 2005/068535. When these dicarboxylic acids are actually copolymerized with a polymer, they may be used in the form of an acid chloride product derived from thionyl chloride or the like, an active ester product, or the like.

[Preparation of polyimide precursor]

The polyimide precursor (polyamic acid) of the present invention is a pyromellitic dianhydride and a diamine (e.g., 4,4'-diaminodiphenylsulfone) used in the structural unit represented by the aforementioned general formula (1). It can be synthesized by making a polycondensation reaction. It is preferable to carry out this reaction in a suitable solvent. Specifically, for example, after dissolving a predetermined amount of 4,4'-DAS in a solvent, a predetermined amount of pyromellitic dianhydride is added to the obtained diamine solution, followed by stirring.

The ratio (molar ratio) of the tetracarboxylic dianhydride component and the diamine component when synthesizing the polyimide precursor is desired to obtain a thermal line expansion coefficient, residual stress, elongation, and yellowness (hereinafter also referred to as YI) of the obtained resin film. From the viewpoint of controlling to a range, it is preferable to set it in the range of tetracarboxylic dianhydride:diamine = 100:90 to 100:110 (0.90 to 1.10 mole parts of diamine per 1 mole part of tetracarboxylic dianhydride), and 100: It is more preferable to set it as the range of 95-100:105 (0.95-1.05 mol parts of diamine with respect to 1 mol part of acid dianhydride).

In this embodiment, when synthesizing the polyamic acid, which is a preferred polyimide precursor, the molecular weight is adjusted by adjusting the ratio of the tetracarboxylic dianhydride component and the diamine component, and the addition of an end-sealing agent (封止劑). It is possible to control. The closer the ratio of the acid dianhydride component and the diamine component to 1:1, and the smaller the amount of the end capping agent is used, the greater the molecular weight of the polyamic acid can be.

As the tetracarboxylic dianhydride component and the diamine component, it is recommended to use a high-purity product. The purity is preferably 98% by mass or more, more preferably 99% by mass or more, and even more preferably 99.5% by mass or more. When a plurality of types of acid dianhydride components or diamine components are used in combination, it is sufficient to have the above purity as the whole of the acid dianhydride components or diamine components, but all types of acid dianhydride components and diamine components to be used are each It is preferable to have the above purity.

As the solvent for the reaction, the tetracarboxylic dianhydride component, the diamine component, and the resulting polyamic acid can be dissolved, and there is no particular limitation as long as it is a solvent in which a high molecular weight polymer is obtained. Specific examples of such a solvent include, for example, an aprotic solvent, a phenolic solvent, an ether and a glycol solvent. In specific examples thereof, as the aprotic solvent, for example, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone ( NMP), N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, the following general formula (7):

[Formula 10]

Wherein, R ₁₂ = Ek M100 amide represented by the group (trade name: Idemitsu heungsan Company), and R ₁₂ = Ek amide B100 (trade name: Idemitsu heungsan Company) represents a group n- butyl amide-based solvents and the like;

lactone solvents such as γ-butyrolactone and γ-valerolactone;

Phosphorus-containing amide solvents such as hexamethylphosphoricamide and hexamethylphosphine triamide;

Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane;

Ketone solvents such as cyclohexanone and methylcyclohexanone;

Tertiary amine solvents such as picoline and pyridine;

Ester solvent such as acetic acid (2-methoxy-1-methylethyl)

My back :

As the phenolic solvent, for example, phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2, 6-xylenol, 3,4-xylenol, 3,5-xylenol, etc.:

As the ether and glycol solvents, for example, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-( 2-methoxyethoxy)ethyl] ether, tetrahydrofuran, 1,4-dioxane, etc.,

Each can be mentioned.

The boiling point of the solvent used for synthesis of the polyamic acid at normal pressure is preferably 60 to 300°C, more preferably 140 to 280°C, and particularly preferably 170 to 270°C. When the boiling point of the solvent is higher than 300°C, a drying step is required for a long time. On the other hand, when the boiling point of the solvent is lower than 60°C, roughness on the surface of the resin film and mixing of air bubbles into the resin film may occur during the drying step, and a uniform film may not be obtained.

Thus, it is preferable to use a solvent having a boiling point of 170 to 270°C, and more preferably a vapor pressure of 250 Pa or less at 20°C from the viewpoint of solubility and edge cratering during application. More specifically, it is preferable to use at least one selected from the group consisting of N-methyl-2-pyrrolidone, γ-butyrolactone, and the compound represented by the general formula (5).

The water content in the solvent is preferably 3000 ppm by mass or less.

These solvents may be used alone or in combination of two or more.

In the resin composition in this embodiment, it is preferable that the content of a molecule having a molecular weight of less than 1,000 is less than 5% by mass.

The existence of a molecule having a molecular weight of less than 1,000 in the resin composition is considered because the water content of the solvent or raw material (acid dianhydride, diamine) used during synthesis is involved. That is, it is considered that the acid anhydride groups of some of the acid dianhydride monomers are hydrolyzed by moisture to become carboxyl groups, and remain in a low-molecular state without becoming high molecular weight. Therefore, it is preferable that the moisture content of the solvent used in the polymerization reaction is as small as possible. The water content of this solvent is preferably 3,000 ppm by mass or less, and more preferably 1,000 ppm by mass or less.

Also about the amount of water contained in the raw material, it is preferable to set it as 3000 mass ppm or less, and it is more preferable to set it as 1000 mass ppm or less.

The moisture content of the solvent is determined from the grade of the solvent used (dehydration grade, general grade, etc.), the solvent container (bottle, 18 liter can, canister can, etc.), the storage state of the solvent (presence of noble gas encapsulation, etc.), and opening. It is thought that the time until use (whether to use immediately after opening, whether to use after a period of time after opening, etc.) is involved. In addition, it is considered that the replacement of the rare gas in the reactor before synthesis, the presence or absence of circulation of the rare gas during synthesis, and the like are also involved. Therefore, (a) when synthesizing the polyimide precursor, it is recommended to use a high-purity product as a raw material, use a solvent with a low moisture content, and take measures to prevent moisture from the environment from entering the system before and during the reaction. It is recommended.

When dissolving each monomer component in a solvent, you may heat it as needed.

(a) The reaction temperature at the time of synthesizing the polyimide precursor is preferably from 0°C to 120°C, more preferably from 40°C to 100°C, and still more preferably from 60 to 100°C. By performing a polymerization reaction at this temperature, a polyimide precursor with a high degree of polymerization is obtained. It is preferable to set it as 1 to 100 hours, and, as for the polymerization time, it is more preferable to set it as 2 to 10 hours. By setting the polymerization time to 1 hour or more, it becomes a polyimide precursor with a uniform polymerization degree, and by setting the polymerization time to 100 hours or less, a polyimide precursor with a high polymerization degree can be obtained.

The polyimide precursor according to the present embodiment may contain other polyimide precursors, if necessary, within a range that does not impair the desired performance of the present invention.

As such a polyimide precursor, a polyimide precursor obtained by polycondensing other acid dianhydrides and other diamines described above can be illustrated, for example.

The mass ratio of the other polyimide precursors according to the present embodiment is (a) 30 mass% or less with respect to all of the polyimide precursors, and 10 mass% or less is the decrease in the oxygen dependence of the YI value and the total light transmittance. From the viewpoint of, it is more preferable.

In a preferred aspect of the present embodiment, a part of the polyimide precursor (a) may be imidized. The imidation ratio in this case is preferably 80% or less, and more preferably 50% or less. This partial imidization is obtained by heating the polyimide precursor (a) and dehydrating cyclization. This heating is preferably 120 to 200°C, more preferably at a temperature of 150 to 180°C, preferably 15 minutes to 20 hours, and more preferably 30 minutes to 10 hours.

Further, to the polyamic acid obtained by the above-described reaction, N,N-dimethylformamide dimethylacetal or N,N-dimethylformamide diethylacetal was added and heated to esterify part or all of the carboxylic acid. After that, by using it as the (a) polyimide precursor in the present embodiment, a resin composition having improved viscosity stability during storage at room temperature can also be obtained. In addition to these ester-modified polyamic acids, the above-described acid dianhydride component is sequentially reacted with one equivalent of a monohydric alcohol and a dehydration condensing agent such as thionyl chloride and dicyclohexylcarbodiimide based on the acid anhydride group. After making it, it can also be obtained by the method of making a diamine component and condensation reaction.

The ratio of the (a) polyimide precursor (preferably polyamic acid) in the resin composition of the present embodiment is preferably 3 to 50% by mass, more preferably 5 to 40% by mass, from the viewpoint of coating film formation properties. , 10 to 30% by mass is particularly preferable.

In the second aspect of the present embodiment, a polyimide precursor having a weight average molecular weight of 40,000 or more and 300,000 or less, and a content of molecules having a weight average molecular weight of less than 1000 is less than 5% by mass, represented by the following general formula (1). Can provide.

[Formula 11]

The polyimide precursor in an embodiment is not limited as long as the weight average molecular weight is 40,000 or more and 300,000 or less, and the content of molecules having a weight average molecular weight of less than 1000 is less than 5% by mass. In order to obtain such a polyimide precursor, it can be achieved by setting the water content in the solvent or the raw material to be less than or equal to a specific range, further increasing the purity of the raw material, and setting the molar ratio of the acid dianhydride to the diamine within a specific range.

Specifically, the water content in the solvent is preferably 3000 ppm or less, more preferably 1500 ppm or less, and particularly preferably 500 ppm or less.

The purity of the raw material is preferably 98% by mass or more, more preferably 99% by mass or more, and particularly preferably 99.5% by mass or more.

Tetracarboxylic dianhydride: diamine = 100: 90 to 100: 110 (0.90 to 1.10 mole parts of diamine with respect to 1 mole part of tetracarboxylic dianhydride), preferably in the range of 100:95 to 100:105 (acid It is more preferable to set it as the range of 0.95 to 1.05 mole parts of diamine) per 1 mole part of dianhydride.

It is preferable that the said polyimide precursor is a structure represented by following General formula (2) from a viewpoint of haze and elongation of the polyimide film obtained.

[Formula 12]

As long as the polyimide precursor has a structure represented by the general formula (1) (preferably, the general formula (2)), even if the yellowness is 20 or less and the residual stress is 25 MPa or less, the elongation is 15 A polyimide film satisfying% or more cannot be provided. In this embodiment, in addition to having a structure represented by the general formula (1), a polyimide precursor having a weight average molecular weight of 40,000 or more and 300,000 or less, and a content of molecules having a weight average molecular weight of less than 1000 is less than 5% by mass is used. By doing so, it is possible to provide a polyimide film further satisfying the elongation. Specifically, a polyimide film having a yellowness of 20 or less, a residual stress of 25 MPa or less, and an elongation of 15% or more in a film thickness of 10 microns after heating at 430°C can be provided.

<Resin composition>

Another aspect of the present invention provides a resin composition containing the aforementioned (a) polyimide precursor and (b) an organic solvent. This resin composition is typically a varnish.

[(b) organic solvent]

The (b) organic solvent in this embodiment is not particularly limited as long as it is capable of dissolving the above-described (a) polyimide precursor and other components optionally used. As such (b) organic solvent, the above-described solvent can be used as a solvent that can be used at the time of synthesis of the (a) polyimide precursor. The preferred organic solvent is also the same as above. The (b) organic solvent in the resin composition of the present embodiment may be the same as or different from the solvent used for synthesizing the (a) polyimide precursor.

(b) It is preferable that the organic solvent is set to an amount such that the solid content concentration of the resin composition is 3 to 50% by mass. Moreover, it is preferable to add after (b) adjusting the composition and amount of an organic solvent so that the viscosity (25 degreeC) of a resin composition may become 500 mPa*s-100,000 mPa*s.

[Other ingredients]

In addition to the components (a) and (b), the resin composition of the present embodiment may further contain (c) a surfactant, (d) an alkoxysilane compound, and the like.

((c) surfactant)

The coating property of the resin composition can be improved by adding a surfactant to the resin composition of the present embodiment. Specifically, occurrence of streaks in the coating film can be prevented.

Examples of such surfactants include silicone surfactants, fluorine surfactants, and nonionic surfactants other than these. Examples of these are silicone surfactants, for example, organosiloxane polymers KF-640, 642, 643, KP341, X-70-092, X-70-093, (above, brand name, manufactured by Shin-Etsu Chemical Industries, Ltd.), SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (above, brand name, manufactured by Tore Dow Corning Silicon), SILWET L-77, L-7001 , FZ-2105, FZ-2120, FZ-2154, FZ-2164, FZ-2166, L-7604 (above, brand name, manufactured by Nippon Unicar), DBE-814, DBE-224, DBE-621, CMS-626 , CMS-222, KF-352A, KF-354L, KF-355A, KF-6020, DBE-821, DBE-712 (Gelest), BYK-307, BYK-310, BYK-378, BYK-333 (above, Brand names, manufactured by Big Chemie Japan), granol (brand names, manufactured by Kyoeisha Chemicals), etc.;

Examples of the fluorine-based surfactant include Megapak F171, F173, R-08 (manufactured by Dai Nippon Ink Chemical Industries, Ltd., brand name), Florade FC4430, FC4432 (Sumitomo 3M Corporation, brand name), and the like;

As nonionic surfactants other than these, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenol ether, etc. are each mentioned, for example.

Among these surfactants, silicone-based surfactants and fluorine-based surfactants are preferred from the viewpoint of coating properties (stripe suppression) of the resin composition, and from the viewpoint of the influence on the YI value and total light transmittance due to the oxygen concentration during the curing process, silicone-based Surfactants are preferred.

When (c) a surfactant is used, the blending amount is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 3 parts by mass with respect to 100 parts by mass of the (a) polyimide precursor in the resin composition.

(d) alkoxysilane compound

In order to make the resin film obtained from the resin composition according to the present embodiment exhibit sufficient adhesion between the support body in a manufacturing process such as a flexible device, the resin composition is (a) 100% by mass of a polyimide precursor. And 0.01-20 mass% of an alkoxysilane compound can be contained. When the content of the alkoxysilane compound with respect to 100% by mass of the polyimide precursor is 0.01% by mass or more, good adhesion to the support can be obtained. Moreover, it is preferable from a viewpoint of storage stability of a resin composition that content of an alkoxysilane compound is 20 mass% or less. The content of the alkoxysilane compound is more preferably 0.02 to 15% by mass, still more preferably 0.05 to 10% by mass, and particularly preferably 0.1 to 8% by mass, based on 100 parts by mass of the polyimide precursor.

By using an alkoxysilane compound as an additive of the resin composition according to the present embodiment, in addition to the above-described improvement of adhesion, the coating property of the resin composition (suppression of stripe unevenness) is further improved, and the YI value of the resulting cured film is cured. May lower the oxygen concentration dependence.

As an alkoxysilane compound, for example, 3-ureidopropyltriethoxysilane, bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, γ -Aminopropyltrimethoxysilane, γ-aminopropyltripropoxysilane, γ-aminopropyltributoxysilane, γ-aminoethyltriethoxysilane, γ-aminoethyltripropoxysilane, γ-aminoethyltribu Oxysilane, γ-aminobutyltriethoxysilane, γ-aminobutyltrimethoxysilane, γ-aminobutyltripropoxysilane, γ-aminobutyltributoxysilane, phenylsilanetriol, trimethoxyphenylsilane, Trimethoxy (p-tolyl) silane, diphenylsilanediol, dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxydi-p-tolylsilane, triphenylsilanol, and alkoxysilane compounds represented by each of the following structures And the like, and it is preferable to use one or more types selected from these.

[Formula 13]

The manufacturing method of the resin composition in this embodiment is not specifically limited. For example, it can use the following method.

When (a) the solvent used when synthesizing the polyimide precursor and the (b) organic solvent are the same, the synthesized polyimide precursor solution can be used as a resin composition. Further, if necessary, in the temperature range of room temperature (25° C.) to 80° C., one or more of (b) organic solvent and other components are added to the polyimide precursor, followed by stirring and mixing, and then used as a resin composition. do. For this stirring and mixing, an appropriate device such as a three-one motor (manufactured by Shinto Chemical Co., Ltd.) equipped with a stirring blade and a rotating revolution mixer can be used. Moreover, you may apply heat of 40-100 degreeC as needed.

On the other hand, when (a) the solvent used when synthesizing the polyimide precursor and (b) the organic solvent are different, the solvent in the synthesized polyimide precursor solution may be used in an appropriate method such as reprecipitation or solvent distillation. After removing by removing (a) the polyimide precursor, in a temperature range of room temperature to 80°C, a resin composition may be prepared by adding (b) an organic solvent and other components as necessary, followed by stirring and mixing.

After preparing the resin composition as described above, a part of the polyimide precursor is dehydrated so that the polymer does not precipitate by heating the composition solution at, for example, 130 to 200°C for 5 minutes to 2 hours. You may do it. Here, by controlling the heating temperature and the heating time, the imidation rate can be controlled. By partially imidizing the polyimide precursor, the viscosity stability during storage of the resin composition at room temperature can be improved. The range of the imidation ratio is preferably 5% to 70% from the viewpoint of balancing the solubility of the polyimide precursor in the resin composition solution and the storage stability of the solution.

It is preferable that the water content of the resin composition according to the present embodiment is 3,000 ppm by mass or less. The moisture content of the resin composition is preferably 2500 ppm by mass or less, preferably 2000 ppm by mass or less, preferably 1500 ppm by mass or less, and more preferably 1,000 ppm by mass or less from the viewpoint of viscosity stability when the resin composition is stored. It is preferable, and it is more preferable that it is 500 mass ppm or less, 300 mass ppm or less is preferable, and 100 mass ppm or less is preferable.

The solution viscosity of the resin composition according to the present embodiment is preferably 500 to 200,000 mPa·s, more preferably 2,000 to 100,000 mPa·s, and particularly preferably 3,000 to 30,000 mPa·s at 25°C. This solution viscosity can be measured using an E-type viscometer (manufactured by Toki Industries, Ltd., VISCONICEHD). If the solution viscosity is lower than 300 mPa·s, it is difficult to apply during film formation, and if it is higher than 200,000 mPa·s, there is a concern that agitation during synthesis becomes difficult.

(a) When synthesizing a polyimide precursor, even if the solution has a high viscosity, it is possible to obtain a resin composition having a good handleability by adding and stirring a solvent after the reaction is completed.

The resin composition of this embodiment has the following characteristics in a preferable aspect.

Polyimide obtained by imidizing the polyimide precursor by applying the resin composition to the surface of the support to form a coating film, and then heating the coating film in a nitrogen atmosphere (in nitrogen with an oxygen concentration of 2,000 ppm or less) at 430°C for 1 hour In a film, it is preferable that the yellowness degree in a 10 micrometers film thickness is 20 or less. The degree of yellowness in the 10 µm film thickness is preferably 18 or less, preferably 16 or less, preferably 14 or less, preferably 13 or less, preferably 10 or less, and 7 or less.

Moreover, it is preferable that the residual stress of the polyimide film obtained in this way is 25 MPa or less. Preferred residual stress is 23 MPa or less, 20 MPa or less, 18 MPa or less, and 16 MPa or less.

Moreover, it is preferable that the glass transition temperature Tg of the polyimide film obtained in this way is 360 degreeC or more. A preferred glass transition temperature Tg is 470°C or higher.

Moreover, it is preferable that the retardation Rth in the 10 micrometers film thickness of the polyimide film obtained in this way is 1000 nm or less. Preferred retardation Rth is 800 nm or less, 700 nm or less, 500 nm or less, 300 nm or less, 200 nm or less, 140 nm or less, and 100 nm or less.

Moreover, it is preferable that the tensile elongation in 10 micrometers film thickness of the polyimide film obtained in this way is 15% or more. Preferred tensile elongation is 20% or more, 25% or more, 30% or more, 35% or more, and 40% or more.

The resin composition according to the present embodiment can be preferably used to form a transparent substrate of a display device such as a liquid crystal display, an organic electroluminescent display, a field emission display, and electronic paper, for example. Specifically, it can be used to form a substrate for a thin film transistor (TFT), a substrate for a color filter, a substrate for a transparent conductive film (ITO, IndiumThinOxide), or the like.

Since the resin precursor of this embodiment can form a polyimide film having a residual stress of 25 MPa or less, it is easy to apply to a display manufacturing process including a TFT element device on a colorless transparent polyimide substrate.

<resin film>

Another aspect of the present invention provides a resin film formed from the aforementioned resin precursor.

In addition, another aspect of the present invention provides a method of producing a resin film from the above-described resin composition.

The resin film in this embodiment,

A step of forming a coating film by applying the aforementioned resin composition on the surface of the support (coating step), and

Heating the support and the coating film to imide the polyimide precursor contained in the coating film to form a polyimide resin film (heating step); and

Step of peeling the polyimide resin film from the support (peeling step)

It characterized in that it comprises a.

Here, the support body is not particularly limited as long as it has heat resistance at the heating temperature of the subsequent step and the peelability is good. For example, a glass (eg, alkali-free glass) substrate;

Silicon wafer;

PET (polyethylene terephthalate), OPP (stretched polypropylene), polyethylene glycol terephthalate, polyethylene glycol naphthalate, polycarbonate, polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylene Resin substrates such as sulfone and polyphenylene sulfide;

Metal substrates, such as stainless steel, alumina, copper, nickel, etc. are used.

In the case of forming a film-shaped polyimide molded body, for example, a glass substrate, a silicon wafer, or the like is preferable, and when forming a film-like or sheet-like polyimide molded body, for example, PET (polyethylene terephthalate), A support made of OPP (stretched polypropylene) or the like is preferred.

Examples of the coating method include coating methods such as doctor blade knife coater, air knife coater, roll coater, rotary coater, flow coater, die coater, and bar coater, and coating methods such as spin coat, spray coat, and dip coat; Printing technologies such as screen printing and gravure printing can be applied.

Although the coating thickness should be appropriately adjusted according to the desired thickness of the resin film and the content of the polyimide precursor in the resin composition, it is preferably about 1 to 1,000 µm. The application step is sufficient to perform at room temperature, but for the purpose of lowering the viscosity and improving workability, the resin composition may be heated in a range of 40 to 80°C.

Following the coating process, a drying process may be performed, or the drying process may be omitted and proceed directly to the next heating process. This drying step is performed for the purpose of removing the organic solvent. When performing the drying process, for example, a suitable device such as a hot plate, a box-type dryer, and a conveyor-type dryer can be used. It is preferable to perform a drying process at 80-200 degreeC, and it is more preferable to perform at 100-150 degreeC. It is preferable to set it as 1 minute-10 hours, and, as for the implementation time of a drying process, it is more preferable to set it as 3 minutes-1 hour.

In this way, a coating film containing a polyimide precursor is formed on the support.

Subsequently, a heating process is performed. The heating step is a step of removing the organic solvent remaining in the coating film in the above drying step, and advancing the imidization reaction of the polyimide precursor in the coating film to obtain a film made of polyimide.

This heating step can be performed using an apparatus such as an inner gas oven, a hot plate, a box-type dryer, and a conveyor-type dryer, for example. This step may be performed simultaneously with the drying step, or both steps may be performed sequentially.

Although the heating process may be performed in an air atmosphere, it is recommended to perform it in an inert gas atmosphere from the viewpoint of safety, transparency of the polyimide film obtained, and YI value. As an inert gas, nitrogen, argon, etc. are mentioned, for example.

Although the heating temperature may be appropriately set depending on the type of the (b) organic solvent, 250°C to 550°C is preferable, and 300 to 450°C is more preferable. If it is 250 degreeC or more, imidization becomes sufficient, and if it is 550 degrees C or less, there are no problems, such as a decrease in transparency and heat resistance of the obtained polyimide film. It is preferable to set the heating time to about 0.5 to 3 hours.

In the present embodiment, the oxygen concentration in the surrounding atmosphere in the heating step is preferably 2,000 ppm by mass or less, more preferably 100 ppm by mass or less, from the viewpoint of transparency and YI value of the polyimide film to be obtained. The mass ppm or less is more preferable. By heating in an atmosphere with an oxygen concentration of 2,000 mass ppm or less, the YI value of the resulting polyimide film can be made 30 or less.

Depending on the use and purpose of the polyimide resin film, a peeling step of peeling the resin film from the support body is required after the heating step. It is preferable to perform this peeling process after cooling the resin film on a support body to about room temperature-50 degreeC.

As this peeling process, the following aspects (1)-(4) are mentioned, for example.

(1) After manufacturing a structure including a polyimide resin film/support by the above method, a laser is irradiated from the support side of the structure to ablate the interface between the support and the polyimide resin film, thereby forming a polyimide resin. How to peel. Examples of the type of laser include solid-state (YAG) laser, gas (UV excimer) laser, and the like. It is preferable to use a spectrum of wavelength 308 nm or the like (refer to Japanese Unexamined Patent Publication 2007-512568, Japanese Unexamined Patent Publication 2012-511173, etc.).

(2) A method of forming a release layer on the support before applying the resin composition to the support, and then obtaining a constitution including a polyimide resin film/release layer/support, and peeling the polyimide resin film. As the peeling layer, a method of using parylene (registered trademark, manufactured by Nippon Parylene Joint Company) or tungsten oxide; A method of using a release agent such as vegetable oil-based, silicone-based, fluorine-based or alkyd-based, etc. may be mentioned (see Japanese Laid-Open Patent Publication 2010-67957, Japanese Laid-Open Patent Publication 2013-179306, and the like).

You may use this method (2) and the laser irradiation of said (1) together.

(3) A method of obtaining a polyimide resin film by using an etched metal substrate as a support to obtain a structure comprising a polyimide resin film/support and then etching the metal with an etchant. As the metal, for example, copper (as a specific example, electrolytic copper foil "DFF" manufactured by Mitsui Metal Mining Co., Ltd.), aluminum, or the like can be used. As the etchant, ferric chloride or the like can be used for copper, and dilute hydrochloric acid can be used for aluminum.

(4) After obtaining a structure body including a polyimide resin film/support by the above method, an adhesive film is affixed to the surface of the polyimide resin film, and the adhesive film/polyimide resin film is separated from the support, Method of separating the polyimide resin film from the post-adhesive film.

Among these peeling methods, method (1) or (2) is appropriate from the viewpoint of the refractive index difference of the front and back, YI value, and elongation of the obtained polyimide resin film, and from the viewpoint of the difference in refractive index of the front and back of the obtained polyimide resin film Method (1) is more appropriate.

In addition, in the method (3), when copper is used as the support, the YI value of the obtained polyimide resin film increases and the elongation tends to decrease. This is considered to be the influence of copper ions.

The thickness of the resin film obtained by the above method is not particularly limited, but it is preferably in the range of 1 to 200 µm, and more preferably 5 to 100 µm.

The resin film according to the present embodiment may have a yellowness YI of 20 or less in a 10 µm film thickness. Such characteristics are, for example, in a nitrogen atmosphere (for example, in nitrogen having an oxygen concentration of 2,000 ppm or less), preferably 400°C to 550°C, more preferably 400°C to 450°C By imidation in °C, it is satisfactorily realized.

The resin film according to the present embodiment may further have a tensile elongation of 15% or more. The tensile elongation of the resin film may further be 20% or more, and particularly 30% or more. Thereby, the resin film according to the present embodiment is excellent in breaking strength when handling a flexible substrate, and therefore, the yield when manufacturing a flexible display can be improved. This tensile elongation can be measured using a commercially available tensile tester using a resin film having a thickness of 10 µm as a sample.

<Laminate>

Another aspect of the present invention provides a laminate comprising a support and a polyimide resin film formed of the above-described resin composition on the surface of the support.

Still another aspect of the present invention provides a method of manufacturing the laminate.

The layered product in this embodiment is a step of forming a coating film by applying the above-described resin composition on the surface of a support (coating step), and a polyimide contained in the coating film by heating the support and the coating film. It can be obtained by the manufacturing method of a laminated body including a process (heating process) of imidizing a precursor and forming a polyimide resin film.

The manufacturing method of the said laminated body can be implemented similarly to the manufacturing method of the above-mentioned resin film except not performing a peeling process, for example.

This laminate can be suitably used, for example, for manufacturing a flexible device.

In more detail, it is as follows.

In the case of forming a flexible display, a glass substrate is used as a support, a flexible substrate is formed thereon, and a TFT or the like is formed thereon. The step of forming a TFT or the like on a flexible substrate is typically performed at a temperature in a wide range of 150 to 650°C. However, when forming LTPS as a TFT, a very high temperature is required compared to amorphous silicon (250° C.) or IGZO (350° C.), and heating of about 400° C. to 550° C. is required.

On the other hand, by these heat history, various physical properties (especially yellowness and elongation) of a polyimide film tend to fall, and when it exceeds 400 degreeC, yellowness and elongation especially fall. By the way, the polyimide film obtained from the polyimide precursor according to the present invention has very little decrease in yellowness and elongation even in a high temperature region of 400°C or higher, and can be used favorably in the region.

Compared with the case where the polyimide film of this embodiment is formed on IGZO, favorable heat cycle test results are obtained when formed on LTPS. For this reason, the polyimide film of this embodiment is preferably used when the device type of the TFT is LTPS.

In addition, in this embodiment, a polyimide film layer containing a polyimide represented by the following general formula (5), and a laminate containing an LTPS layer can be provided.

[Formula 14]

As a manufacturing method of the laminate, after preparing a laminate containing the above-described support and the polyimide resin film formed of the above-described resin composition on the surface of the support, an amorphous silicone layer was formed, and then 400 to 450°C. After performing the dehydrogenation annealing in about 0.5 to 3 hours, the low-temperature polysilicon layer can be formed by crystallization using an excimer laser or the like.

Thereafter, the laminate can be obtained by peeling the glass and the polyimide film by laser peeling or the like.

Further, if necessary, an LTPS layer may be formed after forming an inorganic film such as SiO ₂ or SiN on the polyimide film.

As said polyimide film layer, it is more preferable that it is the following general formula (6) from a viewpoint of haze and elongation.

[Formula 15]

At this time, if the residual stress generated in the glass substrate and the polyimide resin film is high, the laminate made of both expands in the high-temperature TFT formation process and then shrinks during room temperature cooling, warping and breakage of the glass substrate, and the flexible substrate. It may cause problems such as peeling from the glass substrate. In general, since the coefficient of thermal expansion of a glass substrate is smaller than that of a resin, residual stress is generated between the glass substrate and the flexible substrate. As described above, the resin film according to the present embodiment can be preferably used for formation of a flexible display because the residual stress generated between the glass substrate can be 25 MPa or less.

In addition, in the polyimide film according to the present embodiment, the yellowness YI in a 10 μm film thickness when the polyimide film is heated at 430 degrees can be set to 20 or less, and the tensile elongation can be set to 15% or more. have. Thereby, the resin film according to the present embodiment is excellent in breaking strength when handling a flexible substrate, and therefore, the yield when manufacturing a flexible display can be improved.

The above aspect is a description of an embodiment of manufacturing an LTPS-TFT substrate for a flexible display, but an embodiment as a display device is described below.

As a flexible display, an organic EL display is mentioned, for example.

An organic EL display is a so-called flexible display in which a display portion can be flexibly deformed (having flexibility). 1 is a diagram showing a part of the configuration of an organic EL structure unit 25. The organic EL structure part 25 is formed on the lower substrate 2a composed of the glass substrate 21, the light heat exchange film 22, the transparent resin layer 23, and the base coat 24, and constitutes a general organic EL display. It is composed of the same constituent member as the member, for example, an organic EL element 250a emitting red light, an organic EL element 250b emitting green light, and an organic EL element 250c emitting blue light as one unit. , Are arranged in a matrix, and a light emitting region of each organic EL element is defined by partition walls (banks) 251. Each organic EL element includes a lower electrode (anode) 252, a hole transport layer 253, a light-emitting layer 254, and an upper electrode (cathode) 255. Further, on the lower substrate 2a, a plurality of TFTs 256 (a-Si, p-Si, oxide semiconductors) for driving the organic EL element are formed.

(Method of manufacturing organic EL display)

The manufacturing process of this organic EL display 20 includes an organic EL substrate manufacturing process, a sealing substrate manufacturing process, an assembling process for bonding both substrates, and a peeling process for peeling the glass substrate 21·29 do.

A well-known manufacturing process can be applied to the organic EL substrate manufacturing process, the sealing substrate manufacturing process, and the assembling process. Although an example is given below, it is not limited to this. Moreover, the peeling process is the same as the peeling process of the polyimide film mentioned above.

For example, first, after manufacturing an LTPS-TFT substrate for a flexible display by the above-described method, an interlayer insulating film provided with a contact hole is formed using a photosensitive acrylic resin or the like. An ITO film is formed by a sputtering method or the like, and a lower electrode is formed to form a pair with a TFT.

Next, after forming the partition wall with photosensitive polyimide or the like, a hole transport layer and a light emitting layer are formed in each space partitioned by the partition wall. Further, an upper electrode is formed to cover the light emitting layer and the partition wall. By the above process, an organic EL substrate is produced, and a top emission type flexible organic EL display is produced by sealing with a sealing film or the like. You may manufacture a bottom emission type flexible organic EL display by a known method.

In addition, after manufacturing the LTPS-TFT substrate, a color filter glass substrate with colorless and transparent polyimide was prepared, and a seal material made of a thermosetting epoxy resin or the like was applied to one of the TFT substrate and the CF substrate by screen printing. It is applied to a frame pattern excluding the injection port portion, and has a diameter corresponding to the thickness of the liquid crystal layer on the other substrate, and a spherical spacer made of plastic or silica is dispersed.

Then, the TFT substrate and the CF substrate are bonded to each other to cure the sealing material.

Finally, a liquid crystal material is injected into the space surrounded by the TFT substrate, the CF substrate, and the sealing material by a pressure reduction method, and then a thermosetting resin is applied to the liquid crystal injection port, and the liquid crystal material is sealed by heating to form a liquid crystal layer. do. Finally, a flexible liquid crystal display can be manufactured by peeling the glass substrate on the CF side and the glass substrate on the TFT side by a laser peeling method or the like.

Accordingly, another aspect of the present invention provides a display substrate.

Still another aspect of the present invention provides a method of manufacturing the display substrate.

The manufacturing method of the display substrate in this embodiment,

A step of forming a coating film by applying the aforementioned resin composition on the surface of the support (coating step), and

Heating the support and the coating film to imide the polyimide precursor contained in the coating film to form a polyimide resin film (heating step); and

A process of forming an element or a circuit on the polyimide resin film (element/circuit formation process),

Step of peeling the polyimide resin film on which the device or circuit is formed from the support (peel step)

It characterized in that it comprises a.

In the said method, the coating process, a heating process, and a peeling process can each be implemented similarly to the manufacturing method of the resin film mentioned above.

The element/circuit formation process can be performed by a method known to those skilled in the art.

The resin film according to the present embodiment that satisfies the above physical properties is preferably used for applications such as a colorless transparent substrate for flexible displays and a protective film for color filters, etc., whose use is limited due to the yellow color of the existing polyimide film. Further, for example, a protective film, a diffused sheet and a coating film in a TFT-LCD (for example, an interlayer of a TFT-LCD, a gate insulating film, a liquid crystal alignment film, etc.), an ITO substrate for a touch panel, a smartphone It can also be used in fields requiring colorless transparency and low birefringence, such as a cover glass substitute resin substrate.

The resin film and laminate produced using the polyimide precursor and the resin precursor according to the present embodiment can be applied as, for example, a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, etc., in addition to manufacturing a flexible device In particular, it can be preferably used as a substrate. Here, examples of the flexible device to which the resin film and the laminate according to the present embodiment can be applied include a flexible display, a flexible solar cell, a flexible touch panel electrode substrate, a flexible lighting, and a flexible battery.

Example

Hereinafter, the present invention will be described in more detail based on Examples, but these are described for purposes of explanation, and the scope of the present invention is not limited to the following Examples.

Various evaluations in Examples and Comparative Examples were performed as follows.

<Measurement of weight average molecular weight>

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions.

As a solvent, NMP (manufactured by Wako Pure Chemical Industries, for high-performance liquid chromatography, 24.8 mmol/L lithium bromide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.5%) and 63.2 mmol/L phosphoric acid ( Wako Pure Chemical Industries, Ltd. product, for high performance liquid chromatograph) was added and dissolved) was used. The calibration curve for calculating the weight average molecular weight was manufactured using standard polystyrene (manufactured by Tosoh Corporation).

Column: Shodex KD-806M (made by Showa Electric Corporation)

Flow rate: 1.0 ml/min

Column temperature: 40 °C

Pump: PU-2080Plus (manufactured by JASCO)

Detector: RI-2031Plus (RI: differential refractometer, manufactured by JASCO) and UV-2075Plus (UV-VIS: ultraviolet and visible absorber, manufactured by JASCO)

<Evaluation of the content of molecules with a molecular weight of less than 1,000 (low molecular weight content)>

The content of a molecule having a molecular weight of less than 1,000 in the resin was calculated as the ratio (percentage) of the peak area occupied by the component having a molecular weight of less than 1,000 to the peak area of the entire molecular weight distribution using the measurement result of GPC obtained above.

<Evaluation of moisture content>

The moisture content of the synthetic solvent and the resin composition (varnish) was measured using a Karl Fischer moisture measuring device (trace moisture measuring device AQ-300, manufactured by Hiranuma Industrial Co., Ltd.).

<Evaluation of viscosity stability of resin composition>

With respect to the resin composition prepared in each of the Examples and Comparative Examples, viscosity measurement at 23°C was performed using a sample, which was allowed to stand still at room temperature for 3 days after preparation, as a sample after preparation;

Then, the sample which was further stopped still at room temperature for 2 weeks was used as the sample after 2 weeks, and the viscosity measurement at 23 degreeC was performed again. These viscosity measurements were performed using a viscometer (TV-22 manufactured by Toki Industries, Ltd.) equipped with a temperature controller.

Using the above measured values, the rate of change in viscosity for 2 weeks at room temperature was calculated by the following equation.

Viscosity change rate (%) at room temperature for 2 weeks = [(Viscosity of sample after 2 weeks)-(Viscosity of sample after preparation)]/(Viscosity of sample after preparation) × 100

The rate of change in viscosity for 2 weeks at room temperature was evaluated based on the following criteria.

◎: Viscosity change rate is 5% or less (storage stability "excellent")

○: The viscosity change rate is more than 5 and 10% or less (storage stability "good")

X: The viscosity change rate exceeded 10% (storage stability "defect")

<Evaluation of varnish coating property>

The resin composition prepared in each of Examples and Comparative Examples was coated on an alkali-free glass substrate (size 37 × 47 mm, thickness 0.7 mm) using a bar coater so that the film thickness became 15 μm after curing, and then at 140° C. It was prebaked for 60 minutes.

The coatability of the varnish was evaluated by measuring the step difference on the surface of the coating film using a step meter (manufactured by Tencor, model name P-15).

◎: Surface level difference is 0.1 um or less (excellent application)

○: Surface level difference is more than 0.1 and 0.5 um or less (applicability is good)

×: The surface level difference exceeds 0.5 um (coating property "poor")

<Evaluation of residual stress>

Each resin composition was applied by a spin coater on a 6-inch silicon wafer having a thickness of 625 µm ± 25 µm for which "the amount of warpage" was measured in advance, and prebaked at 100°C for 7 minutes. Thereafter, using a vertical cure (manufactured by Koyo Lindbergh, model name VF-2000B), the oxygen concentration in the chamber was adjusted to be 10 ppm by mass or less, and at 430°C for 1 hour The heat curing treatment (curing treatment) was performed to prepare a silicone wafer with a polyimide resin film having a thickness of 10 µm after curing.

The amount of warpage of this wafer was measured using a residual stress measuring device (manufactured by Tencor, model name FLX-2320), and residual stress generated between the silicon wafer and the resin film was evaluated.

<Evaluation of yellowness (YI value)>

The resin composition prepared in each of Examples and Comparative Examples was spin-coated to a 6-inch silicon wafer substrate having an aluminum vapor deposition layer formed on the surface thereof so that the film thickness after curing became 10 µm, and prebaked at 100°C for 7 minutes. Thereafter, using a vertical curing furnace (manufactured by Koyo Lindbergh, model name VF-2000B), the oxygen concentration in the chamber was adjusted to be 10 ppm by mass or less, followed by heat curing treatment at 430°C for 1 hour, A wafer on which a mid resin film was formed was prepared.

The laminated wafer obtained above was immersed in a dilute hydrochloric acid aqueous solution, and the polyimide film was peeled from the wafer to obtain a sample of a polyimide film having an inorganic film formed on the surface thereof.

About the obtained polyimide resin film, the YI value (film thickness conversion of 10 micrometers) was measured using the D65 light source by the Nippon Electric Color Industry Co., Ltd. make (Spectrophotometer: SE600).

<Evaluation of elongation and breaking strength>

A wafer was manufactured in the same manner as in the above <evaluation of yellowness>. Using a dicing saw (DAD 3350 manufactured by Disco Co., Ltd.), a 3 mm-wide incision line was put in the polyimide resin film of the wafer, and then immersed in an aqueous solution of dilute hydrochloric acid overnight, and the resin film piece was peeled off and dried. This was cut into a length of 50 mm to obtain a sample.

For the above sample, the elongation and breaking strength were measured at a test speed of 40 mm/min and an initial weight of 0.5 fs using TENSILON (UTM-II-20 manufactured by Orientec).

[Synthesis Example 1]

To a 3 L separable flask equipped with a stirring rod equipped with an oil bath, while introducing nitrogen gas, NMP1 (1065 g) was added, and 4,4'-diaminodiphenylsulfone (248.3 g) was stirred as a diamine. It was added, and then PMDA (218.12 g) was added as an acid dianhydride, followed by stirring at room temperature for 30 minutes. This was heated up to 50°C and stirred for 12 hours, and then the oil bath was removed and returned to room temperature to obtain a transparent polyamic acid NMP solution (hereinafter, also referred to as varnish) (varnish P-1). The composition here and the weight average molecular weight (Mw) of the obtained polyamic acid are shown in Table 1, respectively. Moreover, the test results of the film cured at 430°C are shown in Table 2.

[Example 1]

To a 3 L separable flask equipped with a stirring rod equipped with an oil bath, NMP2 (1065 g) was added while introducing nitrogen gas, and 4,4'-diaminodiphenylsulfone (248.3 g) was added while stirring as a diamine. Then, PMDA (218.12 g) was added as an acid dianhydride, followed by stirring at room temperature for 30 minutes. This was heated up to 80°C and stirred for 3 hours, then the oil bath was removed and returned to room temperature to obtain a transparent polyamic acid NMP solution (hereinafter, also referred to as varnish) (varnish P-2). The composition here and the weight average molecular weight (Mw) of the obtained polyamic acid are shown in Table 1, respectively. Moreover, the test results of the film cured at 430°C are shown in Table 2.

[Example 2]

Synthesis was carried out in the same manner as in Example 1 except that NMP2 was changed to NMP3 (varnish P-3). The results are shown in Tables 1 and 2.

[Example 3]

In the amine, the same as in Example 2, except that 4,4'-diaminodiphenylsulfone as the first diamine and amine-modified methylphenyl silicone oil at both terminals as the second diamine were added so as to be 99.33:0.67 in a molar ratio. It was synthesized by the method (varnish P-4). The results are shown in Tables 1 and 2.

[Examples 4 to 13]

In the amine, synthesis was carried out in the same manner as in Example 3, except that the type and molar ratio of the first diamine and the second diamine were changed as shown in Table 1 (varnishes P-5 to P-14). The results are shown in Tables 1 and 2.

[Example 14]

In the acid dianhydride, except for adding pyromellitic dianhydride as the first acid dianhydride and biphenyltetracarboxylic dianhydride as the second acid dianhydride in a molar ratio of 80:20, as in Example 2 Synthesis was carried out in the same manner (varnish P-15). The results are shown in Tables 1 and 2.

[Examples 15 to 17]

In the acid dianhydride, synthesis was carried out in the same manner as in Example 2, except that the molar ratio of the first acid dianhydride and the second acid dianhydride was changed as shown in Table 1 (varnishes P-16 to P-18). The results are shown in Tables 1 and 2.

[Example 18]

In diamine, synthesis was carried out in the same manner as in Example 2, except that 4,4'-diaminodiphenylsulfone was replaced with 3,3'-diaminodiphenylsulfone (varnish P-19).

[Comparative Examples 1 to 6]

Synthesis was carried out in the same manner as in Example 2, except that the acid dianhydride and diamine were changed as in Table 1 (varnish P-20 to varnish P-25).

The composition in each of the above Examples and Comparative Examples and the weight average molecular weight (Mw) of the obtained polyamic acid are shown in Table 1, respectively. Moreover, the test results of the film cured at 430°C are shown in Table 2.

The abbreviation of each component in the table is the following meaning, respectively.

PMDA: pyromellitic dianhydride

BPDA: Biphenyltetracarboxylic dianhydride

4,4'-DAS: 4,4'-diaminodiphenylsulfone

3,3'-DAS: 3,3'-diaminodiphenylsulfone

APAB: 4-aminophenyl-4-aminobenzoate

p-PD: p-phenylenediamine

6 FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride

CHDA: 1,4-cyclohexanediamine

DSDA: 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride

HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride

TFMB: 2,2'-bis (trifluoromethyl) benzidine

X-22-1660B-3: Both terminal amine-modified methylphenyl silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd.)

NMP1: 500 ml bottle left for 1 month after opening, moisture content 3,070 ppm

NMP2: 500 ml bottle left for a week after opening, moisture content 1500 ppm

NMP3: After opening 18 ℓ can, moisture content 250 ppm

As is clear from Table 1 and Table 2, the resin compositions of Synthesis Example 1 and Examples 1 to 18 having a structure represented by General Formula (1) have a small residual stress compared to the resin compositions of Comparative Examples 1 to 6 , It can be seen that the yellowness is low and the elongation is high.

In particular, in Examples 1 to 18, in which the weight average molecular weight of the polyimide precursor is 40,000 or more and 300,000 or less, and the content of molecules having a weight average molecular weight of less than 1,000 is less than 5% by mass, the elongation is higher than that of Synthesis Example 1, and is particularly good. Results are being obtained. Specifically, a resin film having a residual stress of 25 MPa or less, a yellowness YI of 20 or less, and an elongation of 15% or more can be obtained.

In addition, when comparing Synthesis Example 1 and Examples 1 and 2, it can be seen that the smaller the moisture content of the solvent used in the polymerization reaction, the smaller the content of molecules having a molecular weight of less than 1,000.

[Synthesis Examples, Examples 1 to 18, Comparative Examples 1 to 6]

An organic EL substrate as shown in Fig. 1 was prepared.

After curing the polyimide precursor varnish of Synthesis Example 1 and Examples and Comparative Examples using a bar coater on a mother glass substrate (thickness of 0.7 mm), after curing to a film thickness of 10 µm, pre-curing at 140° C. for 60 minutes It was baked. Subsequently, using a vertical cure (manufactured by Koyo Lindbergh, model name VF-2000B), the oxygen concentration in the chamber was adjusted to be 10 ppm by mass or less, followed by heat curing treatment at 430° C. for 1 hour, and polyimide A glass substrate on which a resin film was formed was prepared.

Subsequently, a SiN layer was formed with a thickness of 100 nm by CVD (Chemical Vapor Deposition) method.

Subsequently, titanium was formed into a film by a sputtering method, and then patterned by a photolithography method was performed to form a scanning signal line.

Next, a SiN layer was formed to a thickness of 100 nm by the CVD method over the entire glass substrate on which the scanning signal lines were formed. (This is the lower substrate 2a)

Subsequently, an amorphous silicon layer 256 was formed on the lower substrate 2a, dehydrogenation annealing was performed at 430°C for 1 hour, and then an excimer laser was irradiated to form an LTPS layer.

Thereafter, a photosensitive acrylic resin was coated on the entire surface of the lower substrate 2a by a spin coating method, and exposed and developed by a photolithography method to form an interlayer insulating film 258 provided with a plurality of contact holes 257. Formed. A part of each LTPS 256 was made exposed by this contact hole 257.

Next, an ITO film was formed on the entire surface of the lower substrate 2a on which the interlayer insulating film 258 was formed by a sputtering method, exposed and developed by a photolithography method, and patterned by an etching method, and each LTPS The lower electrode 259 was formed to form a pair with.

Further, in each of the contact holes 257, the lower electrode 252 penetrating the interlayer insulating film 258 and the LTPS 256 were electrically connected.

Next, after the partition wall 251 was formed, a hole transport layer 253 and a light emitting layer 254 were formed in each space partitioned by the partition wall 251. Further, an upper electrode 255 was formed so as to cover the light emitting layer 254 and the partition wall 251. An organic EL substrate was prepared by the above process.

Next, the glass substrate, the polyimide film of this embodiment, and the SiN layer were coated with an ultraviolet curing resin around the encapsulation substrate 2b formed in this order, and the encapsulation substrate 2b and the organic EL substrate in an argon gas atmosphere. By bonding, the organic EL element was sealed. Thereby, the hollow part 261 was formed between each organic EL element and the sealing substrate 2b.

Excimer laser (wavelength 308 nm, repetition frequency 300 Hz) is irradiated from the lower substrate 2a side and the sealing substrate 2b side of the laminate thus formed, and peeled with the minimum energy required to peel the entire surface. Was carried out.

With respect to this laminated body, evaluation of the presence or absence of the substrate warpage after peeling, the lighting test, and the cloudiness evaluation of the laminated body was performed. Moreover, it also implemented about the heat cycle test. Table 3 shows the results.

<Substrate warpage>

◎: No warpage

○: There is only slight warpage

△: Rounded by bending

<Lighting test>

○: lit

×: Not lit

<Laminate cloudiness evaluation>

After the layered product was formed, it was observed with the naked eye, and the whole device was set to be ○, the slightly cloudy one was △, and the cloudy one was x.

<heat cycle test>

Using a heat cycle tester manufactured by SPEC, the appearance was observed after a 1000 cycle test was performed at -5°C and 60°C for 30 minutes each (1 minute movement time of the bath).

The thing with no peeling or swelling was set as (circle), the thing in which peeling or swelling was observed in a small part after the test was △, and the thing in which peeling or swelling was observed entirely after the test was set to x.

As is clear from Table 3, in Examples 1 to 18 using the varnishes P-2 to P-19, there was no warpage of the substrate, the lighting test was good, there was no cloudiness, and a laminate having good heat cycle characteristics was obtained. I can. Such a laminate can be preferably used as a low-temperature polysilicon TFT element substrate, for example, a transparent flexible substrate for an organic EL display.

The present invention is not limited to the above-described embodiment, and various modifications can be made and implemented without departing from the spirit of the invention.

Industrial availability

By using the polyimide precursor of the present invention and the resin composition, a resin film having a residual stress of 25 MPa or less, a yellowness YI of 20 or less, and an elongation of 15% or more can be obtained. Such a resin film, for example, can be applied to a semiconductor insulating film, a TFT-LCD insulating film, an electrode protective film, etc., and can be particularly preferably used as a substrate in the manufacture of a flexible display, a substrate for a touch panel ITO electrode, etc. .

2a lower substrate
2b encapsulation substrate
Organic EL device emitting 250a red light
Organic EL device emitting 250b green light
Organic EL device emitting 250c blue light
251 bulkhead (bank)
252 lower electrode (anode)
253 hole transport layer
254 emitting layer
255 upper electrode (cathode)
256 LTPS
257 contact hole
258 interlayer insulating film
259 lower electrode
261 Hollow

Claims (47)

A resin composition for a substrate of a low-temperature polysilicon TFT device, containing a polyimide precursor containing a skeleton derived from a diamine component and an acid dianhydride component, and a solvent,
The polyimide precursor,
(a) the following general formula (1):
[Formula 1]

It is characterized by containing a structure represented by and a structure derived from a silicone diamine component,
When the total mass of the diamine component and the acid dianhydride component is 100% by mass,
Equation (3) below:
[Formula 3]

(In the formula, plural R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200)
The resin composition for a substrate of a low-temperature polysilicon TFT element, wherein the content of the silicon diamine component containing the structure represented by is less than 6% by mass. The method of claim 1,
The polyimide precursor is the following general formula (2):
[Formula 2]

A resin composition for a substrate of a low-temperature polysilicon TFT element containing the structure represented by. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the polyimide precursor has a weight average molecular weight of 40,000 or more and 300,000 or less. The method of claim 1,
When the total weight of the solid content contained in the resin composition is 100% by mass, the amount of molecules contained in the solid content and having a molecular weight of less than 1,000 is less than 5% by mass, the resin composition for a substrate of a low-temperature polysilicon TFT device. The method of claim 4,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the amount of the molecule contained in the solid content and having a molecular weight of less than 1,000 is 1% by mass or less. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the content of the silicone diamine component is 5.9% by mass or less. The method of claim 6,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the content of the silicone diamine component is 3% by mass or less. The method of claim 1,
The polyimide precursor is contained in the polyimide precursor when the total number of moles of the diamine component is 100 mol%, the following general formula (4):
[Formula 4]

(In the formula, R ₁ , R ₂ , and R ₃ each independently represent a monovalent organic group having 1 to 20 carbon atoms. n represents 0 or 1. And a, b and c are integers of 0 to 4.)
The resin composition for a substrate of a low-temperature polysilicon TFT element in which the amount of diamine represented by is 48 mol% or less. The method of claim 8,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the amount of diamine contained in the polyimide precursor represented by the general formula (4) is less than 1 mol%. The method of claim 9,
The resin composition for a substrate of a low-temperature polysilicon TFT element, wherein the amount of diamine contained in the polyimide precursor represented by the general formula (4) is 0.9 mol% or less. The method of claim 8,
The polyimide precursor contains 4-aminophenyl-4-aminobenzoate as a diamine component represented by the general formula (4). A resin composition for a substrate of a low-temperature polysilicon TFT device. The method of claim 11,
The polyimide precursor is a resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the content of the 4-aminophenyl-4-aminobenzoate is 48 mol% or less when the total number of moles of the diamine component is 100 mol%. . The method of claim 12,
The polyimide precursor is a resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 1 mol%. The method of claim 13,
The polyimide precursor is a resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 0.9 mol%. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the polyimide precursor contains diaminodiphenylsulfone as the diamine component. The method of claim 15,
The polyimide precursor is a resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the content of the diaminodiphenylsulfone is 90 mol% or more when the total number of moles of the diamine component is 100 mol%. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the polyimide precursor contains pyromellitic dianhydride as the acid dianhydride component. The method of claim 17,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the polyimide precursor has a content of the pyromellitic dianhydride of 90 mol% or more when the total number of moles of the acid dianhydride component is 100 mol%. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the yellowness of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 20 or less in a film thickness of 10 µm. The method of claim 19,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the yellowness of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 13 or less in a film thickness of 10 µm. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the glass transition temperature of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 360°C or higher. The method of claim 21,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the glass transition temperature of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 470°C or higher. The method of claim 1,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the retardation of the polyimide film obtained by heating the resin composition at 430°C for 1 hour is 1000 nm or less in a film thickness of 10 µm. The method of claim 23,
The resin composition for a substrate of a low-temperature polysilicon TFT device, wherein the retardation of the polyimide film obtained by heating the resin composition at 430° C. for 1 hour is 140 nm or less in a film thickness of 10 μm. The step of applying the resin composition according to claim 1 on the surface of the support, and
The step of forming a polyimide resin film from the resin composition, and
A method for producing a resin film, comprising a step of peeling the polyimide resin film from the support. The method of claim 25,
Prior to the step of peeling the polyimide resin film from the support, a step of irradiating a laser from the support side is performed. A display manufacturing method comprising a method of manufacturing a resin film by the method according to claim 25. The step of applying the resin composition according to claim 1 on the surface of the support, and
The step of forming a polyimide resin film from the resin composition, and
A method for manufacturing a laminate comprising a step of forming a low-temperature polysilicon TFT on the polyimide resin film. The method of claim 28,
The method for producing a laminate, further comprising a step of peeling the polyimide resin film from the support. A method for manufacturing a flexible device including the method for manufacturing a laminate according to claim 28. The following general formula (5):
[Formula 5]

A polyimide layer containing a polyimide containing a structure represented by and a skeleton derived from a silicone diamine component, and further containing a skeleton derived from a diamine component and an acid dianhydride component, and a low-temperature polysilicon TFT layer. As a laminate, characterized in that,
When the total mass of the diamine component and the acid dianhydride component is 100% by mass,
Equation (3) below:
[Formula 3]

(In the formula, plural R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200)
A laminate in which the content of the silicone diamine component containing the structure represented by is less than 6% by mass. The method of claim 31,
A laminate in which the amount of molecules having a molecular weight of less than 1,000 contained in the polyimide layer is less than 5% by mass. As a polyimide resin for a substrate of a low-temperature polysilicon TFT device,
The following general formula (5):
[Formula 5]

A polyimide component containing a diamine component and an acid dianhydride component represented by,
Equation (3) below:
[Formula 3]

(In the formula, plural R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200)
It contains a silicone diamine component containing the structure represented by,
In the polyimide resin, when the total mass of the diamine component and the acid dianhydride component is 100% by mass, the content of the silicone diamine component is less than 6% by mass,
Polyimide resin for substrates of low-temperature polysilicon TFT devices. delete The method of claim 33,
The polyimide resin is the following general formula (6):
[Formula 6]

Polyimide resin for a substrate of a low-temperature polysilicon TFT element containing the structure represented by The method of claim 33,
The polyimide resin is formed by imidizing a polyimide precursor,
The polyimide precursor,
It contains a skeleton derived from a diamine component and an acid dianhydride component,
The following general formula (1):
[Formula 1]

Structure represented by
Equation (3) below:
[Formula 3]

(In the formula, plural R ₃ and R ₄ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200)
It contains a silicone diamine component containing the structure represented by,
When the total mass of the diamine component and the acid dianhydride component is 100% by mass, the content of the silicone diamine component is less than 6% by mass,
A polyimide resin for a substrate of a low-temperature polysilicon TFT element, wherein the weight average molecular weight of the polyimide precursor is 40,000 or more and 300,000 or less. The method of claim 33,
The polyimide component is contained in the polyimide component when the total number of moles of the diamine component is 100 mol%, the following general formula (4):
[Formula 4]

(In the formula, R ₁ , R ₂ , and R ₃ each independently represent a monovalent organic group having 1 to 20 carbon atoms. n represents 0 or 1. And a, b and c are integers of 0 to 4.)
A polyimide resin for a substrate of a low-temperature polysilicon TFT element, wherein the amount of diamine represented by is 48 mol% or less. The method of claim 37,
A polyimide resin for a substrate of a low-temperature polysilicon TFT device, wherein the amount of diamine contained in the polyimide component represented by the general formula (4) is less than 1 mol%. The method of claim 38,
A polyimide resin for a substrate of a low-temperature polysilicon TFT device, wherein the amount of diamine contained in the polyimide component represented by the general formula (4) is 0.9 mol% or less. The method of claim 37,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT device, containing 4-aminophenyl-4-aminobenzoate as a diamine component represented by the general formula (4). The method of claim 40,
The polyimide component is a polyimide for a substrate of a low-temperature polysilicon TFT device, wherein the content of the 4-aminophenyl-4-aminobenzoate is 48 mol% or less when the total number of moles of the diamine component is 100 mol%. Suzy. The method of claim 41,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT device, wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 1 mol%. The method of claim 42,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT device, wherein the content of the 4-aminophenyl-4-aminobenzoate is less than 0.9 mol%. The method of claim 33,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT element containing diaminodiphenylsulfone as the diamine component. The method of claim 44,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT device, wherein the content of the diaminodiphenylsulfone is 90 mol% or more when the total number of moles of the diamine component is 100 mol%. The method of claim 33,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT device, containing pyromellitic dianhydride as the acid dianhydride component. The method of claim 46,
The polyimide component is a polyimide resin for a substrate of a low-temperature polysilicon TFT device, wherein the content of the pyromellitic dianhydride is 90 mol% or more when the total number of moles of the acid dianhydride component is 100 mol%.

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