JP7116366B2 - Method for manufacturing substrate for flexible device - Google Patents

Description

The present invention relates to a flexible device substrate, particularly a method for producing a resin thin film laminate that serves as a base film for a flexible printed circuit board such as a flexible display. It relates to polymer laminates.

In recent years, with the rapid progress in electronics such as liquid crystal displays and organic electroluminescence displays, there has been a demand for thinner, lighter and more flexible devices.
In these devices, various electronic elements such as thin film transistors and transparent electrodes are formed on glass substrates. By replacing the glass material with a flexible and lightweight resin material, the device itself can be made thinner and thinner. It is expected that weight reduction and flexibility will be achieved.
Polyimide has attracted attention as a candidate for such a resin material, and various reports have been made on polyimide films.

For example, Patent Document 1 relates to an invention relating to a polyimide useful as a plastic substrate for flexible displays and a precursor thereof. reported that the polyimide reacted with was excellent in transparency and heat resistance.

Further, in Patent Document 2, by adding silica sol to polyimide, it is possible to improve both the linear expansion coefficient, transparency, and low birefringence, which were the drawbacks of conventional plastic substrates. It is expected to be applied to

On the other hand, when pursuing the advantages of plastic substrates, problems arise in the handling and dimensional stability of the plastic substrate itself. That is, when the plastic substrate is made into a film and made thinner, it is possible to prevent the occurrence of wrinkles and cracks, and to prevent the occurrence of wrinkles and cracks. It becomes difficult to maintain the dimensional accuracy of Therefore, in Non-Patent Document 1, after forming a predetermined functional layer on a plastic substrate that is coated and fixed on glass, a laser is irradiated from the glass side to force the plastic substrate having the functional layer from the glass. A separation method (so-called laser lift-off process (Electronics on Plastic by Laser Release)) has been proposed.

JP 2008-231327 A WO2015/152178

E.I. Haskal et. al. "Flexible OLED Displays Made with the EPLaR Process", Proc. Eurodisplay '07, pp.36-39 (2007)

The technique described in Non-Patent Document 1 mentioned above uses glass as a support base material and forms a functional layer on a plastic substrate fixed to the glass, thereby ensuring the handleability and dimensional stability of the resin substrate. is. However, in this EPLaR method (laser lift-off method), when the resin substrate is separated from the support base material, the interface between the resin substrate and the support base material is destroyed by laser irradiation. There is a possibility that the characteristics of the resin substrate and the functional layer formed thereon may be deteriorated, such as the problem that the functional layer (TFT, etc.) is damaged, or the resin substrate itself is greatly damaged and the transmittance is lowered.

The present invention has been made in view of such circumstances, and is a resin thin film that provides a plastic thin film having excellent performance as a base film for flexible device substrates such as flexible display substrates, without relying on the above laser lift-off technology. To provide a method for producing a laminate, in particular, while maintaining excellent performance such as excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, and handling property and dimensional stability. It aims at providing the manufacturing method of the resin thin film laminated body (substrate for flexible devices) which can ensure.

As a result of intensive studies to achieve the above object, the present inventors have found that when forming a resin thin film in which silicon dioxide is blended with a heat-resistant polymer in order to achieve both heat resistance and optical properties, A resin thin film laminate that can be easily peeled from a supporting substrate while maintaining the characteristics of excellent heat resistance, low retardation, excellent flexibility, and excellent transparency by providing a release layer between them. can be realized, and the present invention has been completed.

〔式中、Ｂ^１は、式（Ｘ－１）～（Ｘ－１２）からなる群から選ばれる４価の基を表す。

（式中、複数のＲは、互いに独立して、水素原子またはメチル基を表し、＊は結合手を表す。）〕
第６観点として、前記含フッ素芳香族ジアミンが、式（Ａ１）で表されるジアミンを含む、第４観点に記載の製造方法に関する。

（式中、Ｂ^２は、式（Ｙ－１）～（Ｙ－３４）からなる群から選ばれる２価の基を表す。）

（式中、＊は結合手を表す。）
第７観点として、前記ポリイミドが、式（１）で表されるモノマー単位、式（２）で表されるモノマー単位、又はその双方のモノマー単位を含む、第４観点に記載の製造方法に関する。

第８観点として、前記樹脂薄膜形成用組成物が、前記耐熱性ポリマーＢと前記二酸化ケイ素粒子とを、質量比で７：３～３：７の割合にて含む、第１観点に記載の製造方法に関する。
第９観点として、前記二酸化ケイ素粒子が、６０ｎｍ以下の平均粒子径を有する、第１観点に記載の製造方法に関する。
第１０観点として、前記剥離層形成用組成物又は前記樹脂薄膜形成用組成物の何れか一方が、さらに架橋剤を含む、第１観点に記載の製造方法に関する。
第１１観点として、硬化が熱または紫外線によるものであることを特徴とする、第１観点に記載の製造方法に関する。
第１２観点として、前記剥離層と前記樹脂薄膜との間の接着性が、ＣＣＪシリーズ（ＪＩＳ５４００）分類で０から５％剥離可能であり、前記支持基材と前記剥離層との間の接着性がＣＣＪシリーズ（ＪＩＳ５４００）分類で５０％剥離可能であることを特徴とする、第１観点に記載の製造方法に関する。
第１３観点として、前記剥離層が、１００μｍ乃至１ｎｍの厚さを有する、第１観点に記載の製造方法に関する。
第１４観点として、前記樹脂薄膜積層体を得る工程が、ナイフによる切断、機械分離及び引きはがしから選ばれる方法を用いて実施されることを特徴とする、第１観点に記載の製造方法に関する。
第１５観点として、第１観点乃至第１４観点のうちいずれか一項に記載の製造方法により製造されたフレキシブル基板に関する。 That is, the present invention, as a first aspect, is a method for manufacturing a resin thin film laminate,
A step of forming a release layer on a supporting substrate using a release layer-forming composition containing a heat-resistant polymer A and an organic solvent;
forming a resin thin film on the release layer using a resin thin film-forming composition containing a heat-resistant polymer B and an organic solvent;
a step of peeling the release layer and the resin thin film together from the support substrate to obtain a resin thin film laminate,
The composition for forming a resin thin film further contains silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area measured by a nitrogen adsorption method, provided that
The composition for forming a release layer does not contain silicon dioxide particles.
As a second aspect, it relates to the production method according to the first aspect, wherein the heat-resistant polymer A and the heat-resistant polymer B are the same polymer.
As a third aspect, the heat-resistant polymer A and the heat-resistant polymer B are each independently at least one polymer selected from polyimide, polybenzoxazole, polybenzobisoxazole, polybenzimidazole, and polybenzothiazole. It relates to the manufacturing method according to the first aspect.
As a fourth aspect, the heat-resistant polymer A and the heat-resistant polymer B each independently contain a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine containing a fluorine-containing aromatic diamine. The present invention relates to the production method according to the first aspect, wherein the polyimide is obtained by imidating a polyamic acid obtained by reacting with a component.
As a fifth aspect, it relates to the production method according to the fourth aspect, wherein the alicyclic tetracarboxylic dianhydride contains a tetracarboxylic dianhydride represented by formula (C1).

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).

(Wherein, multiple Rs independently represent a hydrogen atom or a methyl group, and * represents a bond.)]
As a sixth aspect, it relates to the production method according to the fourth aspect, wherein the fluorine-containing aromatic diamine contains a diamine represented by formula (A1).

(Wherein, B2 represents a divalent group selected from the group consisting of formulas (Y- ¹ ) to (Y-34).)

(In the formula, * represents a bond.)
As a seventh aspect, it relates to the production method according to the fourth aspect, wherein the polyimide contains monomer units represented by formula (1), monomer units represented by formula (2), or both monomer units.

As an eighth aspect, the production according to the first aspect, wherein the composition for forming a resin thin film contains the heat-resistant polymer B and the silicon dioxide particles in a mass ratio of 7:3 to 3:7. Regarding the method.
As a ninth aspect, it relates to the production method according to the first aspect, wherein the silicon dioxide particles have an average particle size of 60 nm or less.
As a tenth aspect, it relates to the production method according to the first aspect, wherein either the release layer forming composition or the resin thin film forming composition further contains a cross-linking agent.
An eleventh aspect relates to the manufacturing method according to the first aspect, characterized in that the curing is by heat or ultraviolet light.
As a twelfth aspect, the adhesiveness between the peeling layer and the resin thin film is 0 to 5% peelable according to the CCJ series (JIS5400) classification, and the adhesiveness between the supporting substrate and the peeling layer. is releasable by 50% according to CCJ series (JIS5400) classification.
A thirteenth aspect relates to the manufacturing method according to the first aspect, wherein the release layer has a thickness of 100 μm to 1 nm.
As a fourteenth aspect, it relates to the manufacturing method according to the first aspect, wherein the step of obtaining the resin thin film laminate is performed using a method selected from cutting with a knife, mechanical separation, and peeling.
A fifteenth aspect relates to a flexible substrate manufactured by the manufacturing method according to any one of the first to fourteenth aspects.

According to the method for manufacturing a resin thin film laminate according to one aspect of the present invention, since the resin thin film laminate can be easily peeled off from the supporting substrate, it has a low coefficient of linear expansion, excellent heat resistance, low retardation, and excellent flexibility. The resin thin film laminate can be easily manufactured with good reproducibility without impairing performance such as durability.
Then, the resulting resin thin film laminate exhibits a low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), low retardation, and excellent flexibility, so flexible devices, especially flexible displays can be suitably used as a substrate for
Such a method for producing a resin thin film laminate according to the present invention is a flexyl device that requires properties such as high flexibility, low coefficient of linear expansion, high transparency (high light transmittance, low yellowness), and low retardation. It is well suited to the developments in the field of substrates for flexible displays, especially substrates for flexible displays.

It is the figure which showed each step of the manufacturing method of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram (sectional drawing) of the laminated body obtained by the manufacturing method of this invention. G1 represents a supporting substrate, LII a release layer, LI a resin thin film, LIV an electrode layer formed on the resin thin film, and the like. FIG. 2 is a schematic diagram of a method for peeling the laminate obtained by the production method of the present invention from the supporting substrate. FIG. 2 is a diagram showing the structures of a release layer, a resin thin film and an intermediate layer in a laminate obtained by the manufacturing method of the present invention; 4 is a cross-sectional photograph (cross-section TEM) of the laminate obtained in Example A. FIG. FIG. 2 shows a cross-sectional photograph (cross-section TEM) (a) of the laminate obtained in Example A and the component composition (b) of each layer. 4 shows Raman IR spectra of the release layer, the resin thin film, and the interface thereof in the laminate obtained in Example A. FIG. 4 is a cross-sectional photograph (cross-section TEM) of the laminate obtained in Example B. FIG. FIG. 3 shows a cross-sectional photograph (cross-section TEM) (a) of the laminate obtained in Example B and the component composition (b) of each layer. 4 shows Raman IR spectra of the release layer, the resin thin film and the interface thereof in the laminate obtained in Example B. FIG.

The present invention will be described in detail below.
In the method for producing a resin thin film laminate of the present invention, after forming a release layer on a support substrate using a release layer forming composition containing a heat-resistant polymer A and an organic solvent, the heat-resistant polymer B and an organic solvent are A resin thin film is formed on the release layer using a composition for forming a resin thin film containing When obtaining the body, silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the nitrogen adsorption method are further contained substantially only in the composition for forming a resin thin film. It is a way to In order to achieve the effect of the present invention, it is essential that silicon dioxide particles are substantially contained only in the composition for forming a resin thin film and substantially not contained in the composition for forming a peeling layer. .
In the present invention, the phrase "substantially free of silicon dioxide particles" means that silicon dioxide particles are not contained except for inadvertent inclusion during the preparation process of the composition. It means that the content of the silicon dioxide particles relative to the heat-resistant polymer B in the release layer-forming composition is less than the content of the silicon dioxide particles relative to the heat-resistant polymer A in the resin thin film-forming composition. If silicon dioxide particles are mixed in the release layer-forming composition, the content of silicon dioxide particles is specifically 5% of the content of silicon dioxide particles with respect to the heat-resistant polymer A of the resin thin film-forming composition. It is preferably less than
Hereinafter, each component constituting the release layer forming composition and the resin thin film forming composition used in the method for producing the resin thin film laminate will be described first.

[Heat resistant polymer (A and B)]
The composition for forming a release layer and the composition for forming a resin thin film used in the present invention contain a heat-resistant polymer A and a heat-resistant polymer B, respectively.
In the present invention, it is preferable that the heat-resistant polymer A contained in the release layer-forming composition and the heat-resistant polymer B contained in the resin thin film-forming composition are the same (hereinafter referred to as heat-resistant polymer A and heat-resistant polymer A). The heat-resistant polymers B are collectively referred to as heat-resistant polymers).
As the heat-resistant polymer used in the present invention, at least one selected from polyimide, polybenzoxazole, polybenzobisoxazole, polybenzimidazole and polybenzothiazole is preferably used. Among them, polyimide is preferable, and in particular polyamic obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorine-containing aromatic diamine, which will be described later. A polyimide obtained by imidizing an acid is preferred.
In the specification of the present application, a heat-resistant polymer is a polymer that exhibits a weight loss of 5% or less at a temperature of 350°C or higher.

[Polyimide]
The polyimide preferably used in the present invention is obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorine-containing aromatic diamine. It is a polyimide obtained by
Among them, the alicyclic tetracarboxylic dianhydride contains a tetracarboxylic dianhydride represented by the following formula (C1), and the fluorine-containing aromatic diamine is represented by the following formula (A1). It preferably contains a diamine that is

〔式中、Ｂ^１は、式（Ｘ－１）～（Ｘ－１２）からなる群から選ばれる４価の基を表す。

（式中、複数のＲは、互いに独立して、水素原子またはメチル基を表し、＊は結合手を表す。）〕

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).

(Wherein, multiple Rs independently represent a hydrogen atom or a methyl group, and * represents a bond.)]

（式中、Ｂ^２は、式（Ｙ－１）～（Ｙ－３４）からなる群から選ばれる２価の基を表す。）

（式中、＊は結合手を表す。）

(Wherein, B2 represents a divalent group selected from the group consisting of formulas (Y- ¹ ) to (Y-34).)

(In the formula, * represents a bond.)

Among the tetracarboxylic dianhydrides represented by the above formula (C1), B ¹ in the formula is represented by formulas (X-1), (X-4), (X-6), and (X-7). It is preferably a compound that is
Among the diamines represented by (A1) above, B2 in the formula is preferably a compound represented by formula (Y ^- 12) or (Y-13).
As a preferred example, a polyimide obtained by imidating a polyamic acid obtained by reacting a tetracarboxylic dianhydride represented by the above formula (C1) with a diamine represented by the above formula (A1) is described later. It contains a monomer unit represented by the formula (2).

In order to obtain a resin thin film laminate having a low coefficient of linear expansion, low retardation and high transparency, which is the object of the present invention, and having excellent flexibility, alicyclic tetracarboxylic dianhydride, for example, the tetracarboxylic dianhydride represented by the above formula (C1) is preferably 90 mol% or more, more preferably 95 mol% or more, In particular, it is optimal that all (100 mol %) is the tetracarboxylic dianhydride represented by the above formula (C1).
Similarly, in order to obtain a resin thin film laminate having the above characteristics of low linear expansion coefficient, low retardation and high transparency and having excellent flexibility, a fluorine-containing aromatic The diamine, for example, the diamine represented by formula (A1) is preferably 90 mol % or more, more preferably 95 mol % or more. Alternatively, all (100 mol %) of the diamine component may be the diamine represented by the above formula (A1).

As an example of a preferred embodiment, the polyimide used in the present invention contains a monomer unit represented by the following formula (1).

As the monomer unit represented by formula (1), those represented by formula (1-1) or (1-2) are preferable, and those represented by formula (1-1) are more preferable.

According to a preferred embodiment of the invention, the polyimide used in the invention contains monomer units represented by formula (2). The polyimide used in the present invention may contain the monomer unit represented by formula (1) and the monomer unit represented by formula (2) at the same time.

As the monomer unit represented by formula (2), those represented by formula (2-1) or (2-2) are preferable, and those represented by formula (2-1) are more preferable.

When the polyimide used in the present invention contains a monomer unit represented by the above formula (1) and a monomer unit represented by the formula (2), the molar ratio in the polyimide chain is represented by the formula (1) monomer unit: monomer unit represented by formula (2)=10:1 to 1:10, more preferably 10:1 to 3:1.

The polyimide of the present invention comprises an alicyclic tetracarboxylic dianhydride component containing a tetracarboxylic dianhydride represented by the above formula (C1) and a diamine component containing a diamine represented by formula (A1). In addition to the monomer units derived from, for example, the monomer units represented by formulas (1) and (2) above, other monomer units may also be included. The content ratio of other monomer units can be arbitrarily determined as long as the properties of the resin thin film laminate formed from the release layer forming composition and the resin thin film forming composition of the present invention are not impaired.
The ratio is derived from the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the formula (C1) and the diamine component containing the diamine represented by the formula (A1). to the number of moles of the monomer units represented by the formula (1) or the monomer units represented by the formula (2), or the monomer units represented by the formula (1) and the formula (2) It is preferably less than 20 mol %, more preferably less than 10 mol %, and even more preferably less than 5 mol %, relative to the total number of moles of the monomer units represented by .

Examples of such other monomer units include, but are not limited to, monomer units having other polyimide structures represented by formula (3).

In formula (3), A represents a tetravalent organic group, preferably a tetravalent group represented by any one of the following formulas (A-1) to (A-4). In the above formula (3), B represents a divalent organic group, preferably a divalent group represented by any one of the following formulas (B-1) to (B-11). In each formula, * represents a bond. In formula (3), when A represents a tetravalent group represented by any of the following formulas (A-1) to (A-4), B is the above formula (Y-1) to ( Y-34) may be a divalent group represented by any one. Alternatively, in formula (3), when B represents a divalent group represented by any of the following formulas (B-1) to (B-11), A is the above formula (X-1) to (X -12) may be a tetravalent group represented by any one of the above.

When the polyimide used in the present invention contains a monomer unit represented by formula (3), A and B include only monomer units composed of only one type of groups exemplified by the following formula, for example. Alternatively, at least one of A and B may contain two or more monomeric units selected from two or more groups exemplified below. In the following formula, * represents a bond.

In addition, in the polyimide used by this invention, each monomer unit is couple|bonded in arbitrary orders.

As a preferred example, a polyimide having a monomer unit represented by the above formula (1) includes bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic acid as a tetracarboxylic dianhydride component. It is obtained by polymerizing a dianhydride and a diamine represented by the following formula (4) as a diamine component in an organic solvent and imidizing the resulting polyamic acid.
Further, when the polyimide used in the present invention has a monomer unit represented by the above formula (2), the polyimide contains 1,2,3,4-cyclobutanetetracarboxylic dianhydride as a tetracarboxylic dianhydride component. and a diamine represented by the following formula (4) as a diamine component are polymerized in an organic solvent, and the resulting polyamic acid is imidized.
Furthermore, when the polyimide used in the present invention has a monomer unit represented by the above formula (2) in addition to the monomer unit represented by the above formula (1), it is represented by the formulas (1) and (2) The polyimide containing each monomer unit is, in addition to the above tetracarboxylic dianhydride as a tetracarboxylic dianhydride component, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and a diamine component of the following formula It is obtained by polymerizing the diamine represented by (4) in an organic solvent and imidating the resulting polyamic acid.

Examples of the diamine represented by the above formula (4) include 2,2′-bis(trifluoromethyl)benzidine, 3,3′-bis(trifluoromethyl)benzidine, and 2,3′-bis(trifluoromethyl). benzidine.
Among them, the diamine component is represented by the following formula (4-1) from the viewpoint of lowering the linear expansion coefficient of the resin thin film laminate of the present invention and increasing the transparency of the resin thin film laminate. It is preferable to use 2,2′-bis(trifluoromethyl)benzidine or 3,3′-bis(trifluoromethyl)benzidine represented by the following formula (4-2), particularly 2,2′- Bis(trifluoromethyl)benzidine is preferably used.

Further, the polyimide used in the present invention contains an alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the above formula (C1) and a diamine represented by the formula (A1). In addition to the monomer units derived from the diamine component, such as the monomer units represented by the above formula (1) and the monomer units represented by the formula (2), other monomer units represented by the above formula (3) When it has, the polyimide containing each monomer unit represented by formula (1), formula (2) and formula (3) is a tetracarboxylic dianhydride component of the above two tetracarboxylic dianhydrides In addition, a tetracarboxylic dianhydride represented by the following formula (5) and a diamine represented by the following formula (6) in addition to the diamine represented by the above formula (4) as a diamine component are mixed in an organic solvent. and imidizing the resulting polyamic acid.

A in formula (5) and B in formula (6) have the same meanings as A and B in formula (3) above.

Specifically, the tetracarboxylic dianhydride represented by formula (5) includes pyromellitic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 3,3 ',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride 4,4′-(Hexafluoroisopropylidene)diphthalic dianhydride, 11,11-bis(trifluoromethyl)-1H-difuro[3,4-b:3′,4′-i]xanthene- 1,3,7,9-(11H-tetraone), 6,6′-bis(trifluoromethyl)-[5,5′-biisobenzofuran]-1,1′,3,3′-tetraone, 4 ,6,10,12-tetrafluorodifuro[3,4-b:3′,4′-i]dibenzo[b,e][1,4]dioxin-1,3,7,9-tetraone, 4 ,8-bis(trifluoromethoxy)benzo[1,2-c:4,5-c′]difuran-1,3,5,7-tetraone, and N,N′-[2,2′-bis( Aromatic tetracarboxylic acids such as trifluoromethyl)biphenyl-4,4′-diyl]bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carbamide); 1,2-dimethyl-1,2 ,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentane Tetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, and 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, etc. and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride.
Among these, A in formula (5) is preferably a tetracarboxylic dianhydride represented by any of the formulas (A-1) to (A-4), that is, 11 ,11-bis(trifluoromethyl)-1H-difuro[3,4-b:3′,4′-i]xanthene-1,3,7,9-(11H-tetraone), 6,6′-bis (trifluoromethyl)-[5,5′-biisobenzofuran]-1,1′,3,3′-tetraone, 4,6,10,12-tetrafluorodifuro[3,4-b:3′ ,4′-i]dibenzo[b,e][1,4]dioxin-1,3,7,9-tetraone and 4,8-bis(trifluoromethoxy)benzo[1,2-c:4, 5-c′]difuran-1,3,5,7-tetraone can be mentioned as a preferred compound.

Examples of diamines represented by formula (6) include 2-(trifluoromethyl)benzene-1,4-diamine, 5-(trifluoromethyl)benzene-1,3-diamine, 5-(trifluoromethyl) ) benzene-1,2-diamine, 2,5-bis(trifluoromethyl)-benzene-1,4-diamine, 2,3-bis(trifluoromethyl)-benzene-1,4-diamine, 2,6 -bis(trifluoromethyl)-benzene-1,4-diamine, 3,5-bis(trifluoromethyl)-benzene-1,2-diamine, tetrakis(trifluoromethyl)-1,4-phenylenediamine, 2 -(trifluoromethyl)-1,3-phenylenediamine, 4-(trifluoromethyl)-1,3-phenylenediamine, 2-methoxy-1,4-phenylenediamine, 2,5-dimethoxy-1,4- Phenylenediamine, 2-hydroxy-1,4-phenylenediamine, 2,5-dihydroxy-1,4-phenylenediamine, 2-fluorobenzene-1,4-diamine, 2,5-difluorobenzene-1,4-diamine , 2-chlorobenzene-1,4-diamine, 2,5-dichlorobenzene-1,4-diamine, 2,3,5,6-tetrafluorobenzene-1,4-diamine, 4,4′-(perfluoro Propane-2,2-diyl)dianiline, 4,4′-oxybis[3-(trifluoromethyl)aniline], 1,4-bis(4-aminophenoxy)benzene, 1,3′-bis(4-amino phenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, benzidine, 2-methylbenzidine, 3-methylbenzidine, 2-(trifluoromethyl)benzidine, 3-(trifluoromethyl)benzidine, 2,2 '-dimethylbenzidine (m-tolidine), 3,3'-dimethylbenzidine (o-tolidine), 2,3'-dimethylbenzidine, 2,2'-dimethoxybenzidine, 3,3'-dimethoxybenzidine, 2,3 '-dimethoxybenzidine, 2,2'-dihydroxybenzidine, 3,3'-dihydroxybenzidine, 2,3'-dihydroxybenzidine, 2,2'-difluorobenzidine, 3,3'-difluorobenzidine, 2,3'- Difluorobenzidine, 2,2'-dichlorobenzidine, 3,3'-dichlorobenzidine, 2,3'-dichlorobenzidine, 4,4'-diaminobenzanilide, 4-aminophenyl -4'-aminobenzoate, octafluorobenzidine, 2,2',5,5'-tetramethylbenzidine, 3,3',5,5'-tetramethylbenzidine, 2,2',5,5'-tetrakis (trifluoromethyl)benzidine, 3,3′,5,5′-tetrakis(trifluoromethyl)benzidine, 2,2′,5,5′-tetrachlorobenzidine, 4,4′-bis(4-aminophenoxy ) biphenyl, 4,4′-bis(3-aminophenoxy)biphenyl, 4,4′-{[3,3″-bis(trifluoromethyl)-(1,1′:3′,1″-terphenyl )-4,4″-diyl]-bis(oxy)}dianiline, 4,4′-{[(perfluoropropane-2,2-diyl)bis(4,1-phenylene)]bis(oxy)}dianiline , and aromatic diamines such as 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5 (or 6) amine; 4,4′-methylenebis(cyclohexylamine ), 4,4′-methylenebis(3-methylcyclohexylamine), isophoronediamine, trans-1,4-cyclohexanediamine, cis-1,4-cyclohexanediamine, 1,4-cyclohexanebis(methylamine), 2, 5-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 3,8-bis(aminomethyl)tricyclo[5.2 .1.0] decane, 1,3-diaminoadamantane, 2,2-bis(4-aminocyclohexyl)propane, 2,2-bis(4-aminocyclohexyl)hexafluoropropane, 1,3-propanediamine, 1 ,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, and 1,9-nonamethylenediamine. group diamines, but are not limited to these.
Among these, aromatic diamines in which B in formula (6) is a divalent group represented by any one of the formulas (B-1) to (B-11) are preferred, that is, 2,2'-bis(trifluoromethoxy)-(1,1'-biphenyl)-4,4'-diamine [also known as 2,2'-dimethoxybenzidine], 4,4'-(perfluoropropane-2,2- diyl)dianiline, 2,5-bis(trifluoromethyl)benzene-1,4-diamine, 2-(trifluoromethyl)benzene-1,4-diamine, 2-fluorobenzene-1,4-diamine, 4, 4′-oxybis[3-(trifluoromethyl)aniline], 2,2′,3,3′,5,5′,6,6′-octafluoro[1,1′-biphenyl]-4,4′ - diamine [a.k.a. octafluorobenzidine], 2,3,5,6-tetrafluorobenzene-1,4-diamine, 4,4′-{[3,3″-bis(trifluoromethyl)-(1, 1′:3′,1″-terphenyl)-4,4″-diyl]-bis(oxy)}dianiline, 4,4′-{[(perfluoropropane-2,2-diyl)bis(4, 1-phenylene)]bis(oxy)}dianiline and 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5 (or 6)amine as preferred diamines can be mentioned.

<Synthesis of polyamic acid>
As described above, the polyimide used in the present invention is a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride represented by the above formula (C1), and a tetracarboxylic dianhydride component represented by the above formula (A1). It is obtained by imidizing a polyamic acid obtained by reacting with a diamine component containing a fluorine-containing aromatic diamine.
Specifically, a preferred example is bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride, and optionally 1,2,3,4-cyclobutanetetracarboxylic Acid dianhydride, further optionally a tetracarboxylic dianhydride component consisting of a tetracarboxylic dianhydride represented by the above formula (5), a diamine represented by the above formula (4) and optionally the above formula ( It is obtained by polymerizing a diamine component composed of the diamine component represented by 6) in an organic solvent and imidizing the resulting polyamic acid.
The reaction from the above two components to polyamic acid is advantageous in that it can proceed relatively easily in an organic solvent and does not produce by-products.

The charging ratio (molar ratio) of the diamine component in the reaction between the tetracarboxylic dianhydride component and the diamine component is appropriately set in consideration of the polyamic acid and the molecular weight of the polyimide obtained by subsequent imidization. However, with respect to 1 diamine component, the tetracarboxylic dianhydride component can usually be about 0.8 to 1.2, for example, about 0.9 to 1.1, preferably 0.1. It is about 95 to 1.02. Similar to a normal polycondensation reaction, the closer this molar ratio is to 1.0, the greater the molecular weight of the polyamic acid produced.

The organic solvent used in the reaction between the tetracarboxylic dianhydride component and the diamine component is not particularly limited as long as it does not adversely affect the reaction and dissolves the polyamic acid produced. Specific examples are given below.
For example, m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, 3- Methoxy-N,N-dimethylpropylamide, 3-ethoxy-N,N-dimethylpropylamide, 3-propoxy-N,N-dimethylpropylamide, 3-isopropoxy-N,N-dimethylpropylamide, 3-butoxy -N,N-dimethylpropylamide, 3-sec-butoxy-N,N-dimethylpropylamide, 3-tert-butoxy-N,N-dimethylpropylamide, γ-butyrolactone, N-methylcaprolactam, dimethylsulfoxide, tetra Methylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, isopropyl alcohol, methoxymethylpentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, Ethyl cellosolve acetate, butyl carbitol, ethyl carbitol, ethylene glycol, ethylene glycol monoacetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol-tert-butyl ether , dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol mono Propyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, tripropylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, Butyl butyrate, butyl ether, diisobutyl ketone, methylcyclohexene, dipropyl ether, dihexene Sil ether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoacetate Ethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, isopropyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionate, 3-methoxypropionate, propyl 3-methoxypropionate , butyl 3-methoxypropionate, diglyme, and 4-hydroxy-4-methyl-2-pentanone, and the like. You may use these individually or in combination of 2 or more types.
Further, even a solvent that does not dissolve the polyamic acid may be mixed with the above solvent and used as long as the generated polyamic acid does not precipitate. Moreover, the water content in the organic solvent inhibits the polymerization reaction and causes hydrolysis of the formed polyamic acid. Therefore, it is preferable to use an organic solvent that has been dehydrated and dried as much as possible.

As a method of reacting the tetracarboxylic dianhydride component and the diamine component in an organic solvent, a dispersion or solution in which the diamine component is dispersed or dissolved in an organic solvent is stirred, and the tetracarboxylic dianhydride is stirred. A method in which the component is added as it is, or a tetracarboxylic acid component dispersed or dissolved in an organic solvent is added. Examples include a method of adding a diamine component and a method of alternately adding a tetracarboxylic dianhydride component and a diamine compound component, and any of these methods may be used.
Further, when the tetracarboxylic dianhydride component and/or the diamine component are composed of a plurality of types of compounds, the reaction may be performed in a premixed state, may be reacted individually sequentially, or may be reacted individually. A low-molecular-weight substance may be mixed and reacted to form a high-molecular-weight substance.

The temperature at which the polyamic acid is synthesized may be appropriately set within the range from the melting point to the boiling point of the solvent used as described above. °C to 150 °C, usually about 0 to 150 °C, preferably about 0 to 140 °C.
The reaction time depends on the reaction temperature and the reactivity of the starting material and cannot be defined unconditionally, but is usually about 1 to 100 hours.
In addition, the reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a high-molecular-weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high, making uniform stirring difficult. Therefore, the total concentration of the tetracarboxylic dianhydride component and the diamine component in the reaction solution is preferably 1 to 50% by mass, more preferably 5 to 40% by mass. The initial stage of the reaction may be carried out at a high concentration, and then the organic solvent may be added.

<Imidation of polyamic acid>
Methods for imidizing polyamic acid include thermal imidization in which a polyamic acid solution is heated as it is, and catalytic imidization in which a catalyst is added to a polyamic acid solution.
When the polyamic acid is thermally imidized in a solution, the temperature is 100° C. to 400° C., preferably 120° C. to 250° C., and the imidization reaction is preferably carried out while removing water generated by the imidization reaction from the system.

Chemical (catalytic) imidization of polyamic acid is carried out by adding a basic catalyst and an acid anhydride to a solution of polyamic acid, and heating the system under temperature conditions of -20 to 250°C, preferably 0 to 180°C. It can be carried out by stirring.
The amount of the basic catalyst is 0.5 to 30 mol times, preferably 1.5 to 20 mol times the amic acid groups of the polyamic acid, and the amount of the acid anhydride is 1 to 50 mol of the amic acid groups of the polyamic acid. times, preferably 2 to 30 mol times.

Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and 1-ethylpiperidine. Among them, pyridine and 1-ethylpiperidine have appropriate basicity to promote the reaction. is therefore preferred.
Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Among them, acetic anhydride is preferably used because purification after completion of the reaction is facilitated.
The imidization rate by catalytic imidization can be controlled by adjusting the catalyst amount, reaction temperature, and reaction time.

In the polyimide resin used in the present invention, the dehydration ring closure rate (imidization rate) of the amic acid groups does not necessarily have to be 100%, and can be arbitrarily adjusted according to the application and purpose. Particularly preferably, it is 50% or more.

In the present invention, after the reaction solution is filtered, the filtrate may be used as it is, or may be diluted or concentrated to form a composition for forming a peeling layer. It may be a forming composition. When filtered in this manner, it is possible not only to reduce the contamination of impurities that may cause deterioration of the heat resistance, flexibility or linear expansion coefficient characteristics of the obtained resin thin film laminate, but also to efficiently remove the composition for forming the release layer, and A composition for forming a resin thin film can be obtained.

In addition, the polyimide used in the present invention is polystyrene by gel permeation chromatography (GPC) in consideration of the strength of the resin thin film laminate, the workability when forming the resin thin film laminate, the uniformity of the resin thin film laminate, etc. The converted weight average molecular weight (Mw) is preferably 5,000 to 200,000.

<Polymer recovery>
A polymer component is recovered from a reaction solution of polyamic acid and polyimide, and when used, the reaction solution is poured into a poor solvent to precipitate. Examples of poor solvents used for precipitation include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and water. The polymer precipitated by adding it to the poor solvent can be filtered and recovered, and then dried at room temperature or under heat under normal pressure or reduced pressure.
In addition, the impurities in the polymer can be reduced by repeating the operation of redissolving the precipitated and recovered polymer in an organic solvent, reprecipitating and recovering (reprecipitation recovery step) 2 to 10 times. It is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent in this case, because the purification efficiency is further improved.

The organic solvent for dissolving the resin component in the reprecipitation recovery step is not particularly limited. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2- pyrrolidone, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketones, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, and the like. Two or more of these solvents may be mixed and used.

[Silicon dioxide]
Silicon dioxide (silica) used in the resin thin film-forming composition of the present invention is not particularly limited, but silicon dioxide in the form of particles, for example, having an average particle size of 100 nm or less, for example, 5 nm to 100 nm, 5 nm to 60 nm, preferably 5 nm to 55 nm. From the viewpoint of obtaining a highly transparent thin film with good reproducibility, the thickness is preferably 5 nm to 50 nm, more preferably 5 nm to 45 nm, even more preferably 5 nm to 35 nm, still more preferably 5 nm to 30 nm.
In the present invention, the average particle size of silicon dioxide particles is an average particle size value calculated from a specific surface area value measured by a nitrogen adsorption method using silicon dioxide particles.

Particularly in the present invention, colloidal silica having the above average particle size can be suitably used, and silica sol can be used as the colloidal silica. As the silica sol, it is possible to use an aqueous silica sol produced by a known method using an aqueous sodium silicate solution as a raw material, and an organosilica sol obtained by substituting an organic solvent for water as a dispersion medium of the aqueous silica sol.
Alternatively, alkoxysilanes such as methyl silicate and ethyl silicate are hydrolyzed and condensed in an organic solvent such as alcohol in the presence of a catalyst (for example, ammonia, an organic amine compound, an alkali catalyst such as sodium hydroxide). It is also possible to use an organosilica sol obtained by replacing the silica sol obtained by solvent substitution with another organic solvent.
Among these, the present invention preferably uses an organosilica sol whose dispersion medium is an organic solvent.

Examples of the organic solvent in the above organosilica sol include lower alcohols such as methyl alcohol, ethyl alcohol and isopropanol; linear amides such as N,N-dimethylformamide and N,N-dimethylacetamide; N-methyl-2- Cyclic amides such as pyrrolidone; ethers such as γ-butyrolactone; glycols such as ethyl cellosolve and ethylene glycol; and acetonitrile. This substitution can be carried out by a conventional method such as a distillation method or an ultrafiltration method.
The above organosilica sol has a viscosity of about 0.6 mPa·s to 100 mPa·s at 20°C.

Examples of commercially available organosilica sols include MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.) and MT-ST (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.). ), trade name MA-ST-UP (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MA-ST-M (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MA-ST- L (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST-S (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST (isopropanol-dispersed silica sol, Nissan Chemical Industries ( Ltd.), trade name IPA-ST-UP (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA-ST-L (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name IPA -ST-ZL (isopropanol dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name NPC-ST-30 (n-propyl cellosolve dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name PGM-ST (1- Methoxy-2-propanol dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name DMAC-ST (dimethylacetamide dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name XBA-ST (xylene / n-butanol mixed solvent Dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name EAC-ST (ethyl acetate dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name PMA-ST (propylene glycol monomethyl ether acetate dispersed silica sol, Nissan Chemical Industries ( Ltd.), trade name MEK-ST (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MEK-ST-UP (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name MEK-ST -L (methyl ethyl ketone dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.) and brand name MIBK-ST (methyl isobutyl ketone dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), but are not limited thereto.
In the present invention, silicon dioxide, for example, silicon dioxide such as those listed in the above products used as organosilica sol, may be used in combination of two or more.

[Crosslinking agent]
The composition for forming a release layer and the composition for forming a resin thin film used in the present invention may further contain a cross-linking agent. When a cross-linking agent is used in the present invention, it is preferable to add it only to either the release layer-forming composition or the resin thin film-forming composition. It is preferable to mix a cross-linking agent.
The cross-linking agent used here is a compound composed only of hydrogen atoms, carbon atoms and oxygen atoms, or a compound composed only of these atoms and nitrogen atoms, which includes a hydroxy group, an epoxy group and a carbon atom number of 1 to It is a cross-linking agent comprising a compound having two or more groups selected from the group consisting of 5 alkoxy groups and having a ring structure. By using such a cross-linking agent, a composition for forming a release layer not only provides a resin thin film laminate having excellent solvent resistance and is suitable for flexible device substrates with good reproducibility, but also has improved storage stability. , a composition for forming a resin thin film can be realized.
Among them, the total number of hydroxy groups, epoxy groups and alkoxy groups having 1 to 5 carbon atoms per compound in the cross-linking agent is preferably It is 3 or more, and is preferably 10 or less, more preferably 8 or less, and still more preferably 6 or less from the viewpoint of realizing the flexibility of the obtained resin thin film laminate with good reproducibility.

Specific examples of the ring structure of the cross-linking agent include aryl rings such as benzene, nitrogen-containing heteroaryl rings such as pyridine, pyrazine, pyrimidine, pyridazine, and 1,3,5-triazine, cyclopentane, cyclohexane, and cyclo Cycloalkane rings such as heptane, piperidine, piperazine, hexahydropyrimidine, hexahydropyridazine, and cyclic amines such as hexahydro-1,3,5-triazine.

The number of ring structures per compound in the cross-linking agent is not particularly limited as long as it is 1 or more. 2 is preferred.
When two or more ring structures are present, the ring structures may be condensed, and an alkane- The ring structures may be bonded to each other via a linking group such as a diyl group.

The molecular weight of the cross-linking agent is not particularly limited as long as it has cross-linking ability and dissolves in the solvent used. Considering availability, price, etc., it is preferably about 100 to 500, more preferably about 150 to 400.

The crosslinker may further have groups derivable from hydrogen, carbon, nitrogen and oxygen atoms such as ketone groups, ester groups (bonds) and the like.

Preferred examples of the cross-linking agent include compounds represented by the following formulas (K1) to (K5), and one preferred embodiment of the formula (K4) is a compound represented by the formula (K4-1). However, one preferred embodiment of formula (K5) includes a compound represented by formula (5-1).

In the above formula, each of A ¹ and A ² independently represents an alkane-diyl group having 1 to 5 carbon atoms such as methylene, ethylene, trimethylene and propane-2,2-diyl. Of these, A ¹ is preferably a methylene group or an ethylene group, more preferably a methylene group, and A ² is preferably a methylene group or a propane-2,2-diyl group.

Each X independently of each other is a hydroxy group, an epoxy group (oxa-cyclopropyl group), or a methoxy group, an ethoxy group, a 1-propyloxy group, an isopropyloxy group, a 1-butyloxy group, a t-butyloxy group, and the like. represents an alkoxy group having 1 to 5 carbon atoms.
Among them, considering the availability and price of the cross-linking agent, X is preferably an epoxy group in the formulas (K1) and (K5), and a C 1-5 group in the formulas (K2) and (K3). Alkoxy groups are preferred, and hydroxy groups are preferred in formula (K4).

In formula (K4), each n represents the number of —(A ¹ —X) groups bonded to a benzene ring and is independently an integer of 1 to 5, preferably 2 to 3, more preferably 3.

In each compound, each A ¹ is preferably the same group, and each X is preferably the same group.

The compounds represented by the above formulas (K1) to (K5) include skeleton compounds such as aryl compounds, heteroaryl compounds, and cyclic amines having the same ring structure as the ring structure in each of these compounds, epoxyalkyl halide compounds, It can be obtained by reacting an alkoxy halide compound or the like with a carbon-carbon coupling reaction or an N-alkylation reaction, or by hydrolyzing the alkoxy site of the resulting product.

The cross-linking agent may be a commercially available product or one synthesized by a known synthesis method.
Commercially available products include CYMEL (registered trademark) 300, 301, 303LF, 303ULF, 304, 350, 3745, XW3106, MM-100, 323, 325, 327, 328, 385, 370, 373, 380, 1116, 1130, 1133, 1141, 1161, 1168, 3020, 202, 203, 1156, MB-94, MB- 96, MB-98, 247-10, 651, 658, 683, 688, 1158, MB-14, MI-12-I, MI-97-IX, U-65 , U-15, U-80, U-21-511, U-21-510, U-216-8, U-227-8, U-1050-10, U-1052 -8, U-1054, U-610, U-640, UB-24-BX, UB-26-BX, UB-90-BX, UB-25-BE, UB-30 -B, U-662, U-663, U-1051, UI-19-I, UI-19-IE, UI-21-E, UI-27-EI, U-38 -I, UI-20-E 659, 1123, 1125, 5010, 1170, 1172, NF3041, and NF2000, etc. (manufactured by allnex); TEPIC (registered trademark) V, the same S, HP, L, PAS, VL, and UC (manufactured by Nissan Chemical Industries, Ltd.), TM-BIP-A (manufactured by Asahi Organic Chemicals Industry Co., Ltd.), 1, 3, 4 ,6-tetrakis(methoxymethyl)glycoluril (hereinafter abbreviated as TMG) (manufactured by Tokyo Chemical Industry Co., Ltd.), 4,4′-methylenebis(N,N-diglycidylaniline) (manufactured by Aldrich), HP- 4032D, HP-7200L, HP-7200, HP-7200H, HP-7200HH, HP-7200HHH, HP-4700, HP-4770, HP-5000, HP-6000, HP-4710, EXA-4850-150, EXA- 4850-1000, EXA-4816, and HP-820 (DIC Corporation), TG-G (Shikoku Chemical Industry Co., Ltd.) and the like.

Preferred specific examples of the cross-linking agent are shown below, but are not limited thereto.

The amount of the cross-linking agent is determined appropriately according to the type of the cross-linking agent, etc., and cannot be categorically defined. 50% by mass or less, preferably 100% by mass or less, relative to the total mass of the polyimide and the silicon dioxide contained in the composition for use, from the viewpoint of ensuring the flexibility of the resulting resin thin film laminate and suppressing brittleness. From the viewpoint of ensuring the solvent resistance of the resin thin film laminate obtained, it is 0.1% by mass or more, preferably 1% by mass or more.

[Organic solvent]
The composition for forming a peeling layer and the composition for forming a resin thin film used in the present invention contain an organic solvent. The organic solvent is not particularly limited and includes, for example, the same specific examples as the reaction solvent used in the preparation of the polyamic acid and polyimide. More specifically, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2-pyrrolidone, γ- butyrolactone and the like. In addition, an organic solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and γ-butyrolactone are preferred from the viewpoint of obtaining a highly flat resin thin film laminate with good reproducibility.

[Composition for forming release layer]
The release layer-forming composition used in the present invention contains the heat-resistant polymer and an organic solvent, and optionally contains a cross-linking agent. As described above, the composition substantially contains silicon dioxide. It does not. The solid content and viscosity of the composition for forming a release layer conform to those for the composition for forming a resin thin film described below.

[Composition for resin thin film formation]
The composition for forming a resin thin film used in the present invention contains the heat-resistant polymer, silicon dioxide and an organic solvent, and may optionally contain a cross-linking agent. Here, the composition for forming a resin thin film is uniform and phase separation is not observed.
In the composition for forming a resin thin film, the mixing ratio of the heat-resistant polymer and the silicon dioxide is preferably heat-resistant polymer:silicon dioxide=10:1 to 1:10, more preferably 8. :2 to 2:8, for example 7:3 to 3:7.
The solid content of the resin thin film-forming composition is usually about 0.5 to 30% by mass, preferably about 5 to 25% by mass. If the solid content concentration is less than 0.5% by mass, the film formation efficiency in producing a resin thin film will be low, and the viscosity of the resin thin film-forming composition will be low, so that a coating film with a uniform surface cannot be obtained. Hateful. On the other hand, if the solid content concentration exceeds 30% by mass, the viscosity of the composition for forming a resin thin film becomes too high, and there is a possibility that the film formation efficiency may deteriorate and the surface uniformity of the coating film may be lacking. The solid content (solid content concentration) referred to herein means the total mass of components other than the organic solvent, and even liquid monomers are included in the weight as solid content.
The viscosity of the composition for forming a resin thin film is appropriately set in consideration of the thickness of the resin thin film to be produced, but the purpose is to obtain a resin thin film having a thickness of about 5 to 50 μm with good reproducibility. In that case, it is usually about 500 to 50,000 mPa·s, preferably about 1,000 to 20,000 mPa·s at 25°C.

<Other ingredients>
In addition, various organic or inorganic low-molecular-weight or high-molecular-weight compounds may be added to the release layer-forming composition and the resin thin film-forming composition in order to impart processing properties and various functionalities. For example, catalysts, antifoaming agents, leveling agents, surfactants, dyes, plasticizers, fine particles, coupling agents, sensitizers and the like can be used. For example, a catalyst may be added for the purpose of reducing the retardation and linear expansion coefficient of the resin thin film laminate.

The release layer-forming composition includes, for example, the polyimide obtained by the above-described method as a heat-resistant polymer, optionally a cross-linking agent, and optionally other components (various organic or inorganic low-molecular-weight or high-molecular-weight compounds ) can be obtained by dissolving in the above organic solvent.

The composition for forming a resin thin film includes, for example, polyimide and silicon dioxide obtained by the above-described method as a heat-resistant polymer, optionally a cross-linking agent, and optionally other components (various organic or inorganic low-molecular-weight or polymer compound) can be obtained by dissolving it in the above-mentioned organic solvent. Alternatively, silicon dioxide may be added to the reaction solution after preparation of the polyimide, and if desired, the organic solvent may be further added.
As described above, when a cross-linking agent is used in the present invention, it is used in either the release layer-forming composition or the resin thin film-forming composition.

In the present invention, the resin contained in the composition for forming the release layer and the resin contained in the composition for forming the resin thin film are the same as described above from the viewpoint of not affecting the properties. Preferably. In addition, substantially only the composition for forming a resin thin film further contains silicon dioxide particles. The method for preparing each composition is not particularly limited as long as these suitable conditions are met. Therefore, in the method of the present invention, for example, after first preparing a composition for forming a release layer, silicon dioxide particles are added to a part of the obtained composition for formation of a release layer as described above, and if desired, an organic By further adding a solvent, the release layer-forming composition and the resin thin film-forming composition can be easily prepared, and these can be used in the method of the present invention.

<Method for manufacturing resin thin film laminate>
[Step of Forming Peeling Layer]
This step is a step of forming a release layer on a support substrate using the release layer-forming composition described above.
Specifically, the composition for forming a release layer is applied onto a support substrate, and dried and heated to remove the organic solvent, resulting in excellent heat resistance, low retardation, excellent flexibility, and transparency. It is possible to obtain a peelable layer that can be easily peeled off from the support substrate by at least one method selected from the group consisting of cutting with a knife, mechanical separation and simultaneous peeling while maintaining excellent properties such as excellent adhesion. Thus, a flexible device substrate can be obtained.

Examples of the supporting substrate include plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetylcellulose, ABS, AS, norbornene resin, etc.), metals, stainless steel (SUS), wood, paper, glass, silicon wafer, slate, and the like.
In particular, from the viewpoint that existing equipment can be used, it is preferable that the supporting substrate to be applied is glass or a silicon wafer, and glass is preferable because the obtained peeling layer exhibits good peelability. More preferred. The coefficient of linear expansion of the supporting substrate to be applied is preferably 40 ppm/°C or less, more preferably 30 ppm/°C or less, from the viewpoint of warping of the supporting substrate after coating.

The method of applying the release layer-forming composition to the supporting substrate is not particularly limited, but examples include cast coating, spin coating, blade coating, dip coating, roll coating, and bar coating. , a die coating method, an inkjet method, a printing method (letterpress, intaglio, lithography, screen printing, etc.) and the like, and these can be appropriately used depending on the purpose.

The heating temperature is preferably 500° C. or lower, more preferably 450° C. or lower. However, if the temperature exceeds 300°C, yellowing may occur. Since it is sufficiently small as described in , it has little effect on the characteristics. Further, when the composition for forming a resin thin film is applied on the formed release layer, the higher the final baking temperature, the lower the rate at which the release layer dissolves in the composition for forming a resin thin film. When the temperature is 400°C, the peeling layer is difficult to dissolve, so that the boundary between the peeling layer and the resin thin film becomes clear. By dissolving, the boundary between the peeling layer and the resin thin film becomes gradation, but in either case, the effect of the present invention is exhibited.
In addition, considering the heat resistance and linear expansion coefficient characteristics of the obtained release layer, after heating the applied release layer forming composition at 40 ° C. to 100 ° C. for 5 minutes to 2 hours, the heating temperature is increased stepwise. Finally, it is desirable to heat at a temperature in the range of over 175° C. to 450° C. for 30 minutes to 2 hours. Thus, by heating at two or more stages of temperature for drying the solvent and for promoting molecular orientation, low thermal expansion characteristics can be exhibited with better reproducibility.
In particular, the applied release layer-forming composition is heated at 40° C. to 100° C. for 5 minutes to 2 hours, then heated at over 100° C. to 175° C. for 5 minutes to 2 hours, and then in the range of over 175° C. to 450° C. It is preferable to heat at a temperature of 5 minutes to 2 hours.
Equipment used for heating includes, for example, a hot plate and an oven. The heating atmosphere may be under air or under an inert gas such as nitrogen, and may be under normal pressure or under reduced pressure, and different pressures may be applied in each stage of heating. may

Further, in this step, a fine structure (intermediate layer) may be formed on the surface of the release layer by a coating technique in order to further increase the adhesiveness between the release layer and the resin thin film formed thereafter. In this case, specifically, it is preferable to form a fine structure on the surface of the release layer before curing the release layer, for example, after coating the release layer-forming composition, or during subsequent step heating.

The thickness of the peeling layer is appropriately determined in consideration of the type of flexible device within the range of about 1 nm to 200 μm, but in order to achieve the effect of the present invention, it is at least thicker than the diameter of the silica particles. It is necessary. Especially when it is assumed that the resin thin film laminate is used as a substrate for a flexible display, it is usually about 10 nm to 10 μm, preferably about 100 nm to 5 μm, and the desired thickness is obtained by adjusting the thickness of the coating film before heating. to form a release layer of

[Process of forming resin thin film]
This step is a step of forming a resin thin film on the peeling layer using the composition for forming a resin thin film of the present invention. This step can be said to be a step of forming a resin thin film laminate including a release layer and a resin thin film formed thereon on a support substrate.
Specifically, the composition for forming a thin film is applied onto the release layer formed on the support substrate, dried and heated to remove the organic solvent, thereby achieving high heat resistance and high transparency. , it is possible to obtain a resin thin film having moderate flexibility, a moderate coefficient of linear expansion, and a small retardation.
Further, in this step, part of the peeling layer is dissolved by the organic solvent contained in the composition for forming a resin thin film, so that the resin thin film and the peeling layer adhere to each other, and the adhesion between the two is strengthened.

The method of applying the composition for forming a resin thin film on the release layer, the heating temperature, the equipment used for heating, and the thickness of the resin thin film conform to the conditions described in the step of forming the release layer.

In the resin thin film laminate formed on the supporting substrate in this way, the adhesive force of the resin thin film to the release layer is greater than the adhesive force of the release layer to the supporting substrate in order to achieve easy peeling from the supporting substrate. is preferably large.
Specifically, the adhesiveness between the peeling layer and the resin thin film is 0 to 1 (0 to 5% peelable) in the CCJ series (JIS5400) classification, and the supporting substrate and the peeling layer It is preferable that the adhesiveness between them is 5 (50% or more can be peeled off) in the CCJ series (JIS5400) classification. The CCJ series is defined as a classification from 0 to 5, where a classification of 0 means that 0% of the square area can be peeled, a classification of 1 means that 1-5% of the square area can be peeled, and a classification of 2. is 6-10% of the square area, 3 is 11-25% of the square area, 4 is 26-50% of the square area, and 5 is 50% of the square area. It means that each of the above can be peeled off. In other words, under the conditions of a cross-cut test according to JIS K5400, the number of square peelings of the resin thin film from the peeling layer is classified 0 to 2, and the number of square peelings of the peeling layer from the support substrate is classification 5. is preferably.

[Step of obtaining resin thin film laminate]
In this step, the peeling layer and the resin thin film are peeled together from the supporting substrate to obtain a resin thin film laminate.
The method for peeling the resin thin film laminate thus formed from the supporting substrate is not particularly limited. For example, the resin thin film laminate is cooled together with the supporting substrate, and the resin thin film laminate is cut and separated. and a method of peeling by applying tension through a roll. In particular, at least one method selected from cutting with a knife, mechanical separation, and peeling can be applied as the method for peeling the resin thin film laminate from the supporting substrate in the present invention.

As described above, according to the method of the present invention, the adhesiveness between the peeling layer and the resin thin film is stronger than the adhesion between the peeling layer and the supporting substrate, so that the peeling layer and the resin thin film are integrated. It can be easily peeled off from the supporting substrate to obtain a resin thin film laminate.
In the present invention, the thickness of the resin thin film laminate can be appropriately determined within the range of about 1 μm to 200 μm in consideration of the type of flexible device. The thickness of the release layer is preferably 1 to 35% of the thickness (100%) of the resin thin film laminate.

The resin thin film laminate obtained in one preferred embodiment of the present invention can achieve high transparency with a light transmittance of 75% or more at a wavelength of 400 nm.
Furthermore, the resin thin film laminate can have a linear expansion coefficient as low as 60 ppm/°C or less, particularly 10 ppm/°C to 35 ppm/°C, at 50°C to 200°C, for example. It can have a linear expansion coefficient of 80 ppm/°C or less, particularly a low value of 15 ppm/°C to 55 ppm/°C, and is excellent in dimensional stability during heating.
In particular, the resin thin film laminate is represented by the product of birefringence (difference between two orthogonal in-plane refractive indices) and film thickness (thickness of laminate) when the wavelength of incident light is 590 nm. The in-plane retardation R ₀ and the two birefringences (differences between the two in-plane refractive indices and the thickness direction refractive index) when viewed from the cross section in the thickness direction, respectively, to the film thickness (laminate It is characterized in that the thickness direction retardation _Rth , which is the average value of the two phase differences obtained by multiplying by the thickness), is very small. The resin thin film laminate obtained by the production method of the present invention has a retardation R _th in the thickness direction of less than 700 nm, such as 660 nm or less, such as 10 nm, when the average film thickness (average thickness of the laminate) is 15 μm to 40 μm. ˜660 nm, an in-plane retardation R ₀ of less than 4, such as 0.3-3.9, and a very low birefringence Δn of less than 0.02, such as 0.0003-0.019 .
Thus, the retardation can be reduced in the resin thin film laminate obtained by the manufacturing method of the present invention.

Since the resin thin film laminate obtained by using the production method of the present invention described above has the above properties, it satisfies each of the conditions required as a base film for a flexible display substrate, and the base film for a flexible display substrate. It can be particularly preferably used as. That is, the present invention is suitable as a method for manufacturing a flexible device substrate.

FIG. 1 shows an example of manufacturing a flexible device using the manufacturing method of the present invention.
As shown in FIG. 1, first, a release layer is formed on a support substrate, and a resin thin film is formed on the release layer to form a resin thin film laminate. Thereafter, after forming a functional layer on the resin thin film laminate, these are put together and peeled off to obtain a flexible device.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

Abbreviations used in the following examples have the following meanings.
<Acid dianhydride>
BODAxx: bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic dianhydride CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride <diamine>
TFMB: 2,2'-bis (trifluoromethyl) benzidine <organic solvent>
GBL: γ-butyrolactone

In the examples, the equipment and conditions used for preparation of samples and analysis and evaluation of physical properties are as follows.
1) Measurement of number-average molecular weight and weight-average molecular weight Columns: KD803 and KD805, column temperature: 50° C., elution solvent: DMF, flow rate: 1.5 ml/min, calibration curve: standard polystyrene.
2) Coefficient of linear expansion (CTE)
Using TMA Q400 manufactured by TA Instruments, the thin film (or laminate) is cut into a size of 5 mm in width and 16 mm in length, and first heated at 10 ° C./min to 50 to 350 ° C. (first heating). Then, after cooling to 50 ° C. by decreasing the temperature by 10 ° C./min, heating (second heating) by increasing the temperature by 10 ° C./min to 50 to 420 ° C., the second heating of 50 ° C. to 200 It was obtained by measuring the coefficient of linear expansion (CTE [ppm/°C]) at °C. A load of 0.05 N was applied throughout the first heating, cooling and second heating.
3) 5% weight loss temperature (Td _5% )
The 5% weight loss temperature (Td _5% [°C]) is obtained by using a TGA Q500 manufactured by TA Instruments Co., Ltd., and heating about 5 to 10 mg of a thin film (or laminate) from 50 to 800 ° C. at a rate of 10 ° C./min in nitrogen. It was obtained by measuring
4) Light transmittance (transparency) ( _T308nm , _T400nm , _T550nm ) and CIE b value (CIE b ^* )
Light transmittance at wavelengths of 308 nm, 400 nm and 550 nm (T _{308 nm} , T 400 _nm , T _{550 nm} [%]) and CIE b value (CIE b ^* ) were measured using a _SA4000 spectrometer manufactured by Nippon Denshoku Industries Co., Ltd. Measurements were made at room temperature using air as a reference.
5) Retardation (R _th , R ₀ )
Thickness direction retardation (R _th ) and in-plane retardation (R ₀ ) were measured at room temperature using KOBURA 2100ADH manufactured by Oji Scientific Instruments.
The thickness direction retardation (R _th ) and in-plane retardation (R ₀ ) are calculated by the following equations.
R ₀ = (Nx−Ny)×d=ΔNxy×d
R _th = [(Nx+Ny)/2−Nz]×d=[(ΔNxz×d)+(ΔNyz×d)/2
Nx, Ny: two in-plane orthogonal refractive indices (Nx>Ny, Nx is also referred to as the slow axis and Ny as the fast axis)
Nz: Refractive index in the direction of thickness (perpendicular) to the surface d: Film thickness (thickness of laminate)
ΔNxy: difference between two in-plane refractive indices (Nx-Ny) (birefringence)
ΔNxz: the difference between the in-plane refractive index Nx and the thickness direction refractive index Nz (birefringence)
ΔNyz: the difference between the in-plane refractive index Ny and the thickness direction refractive index Nz (birefringence)
6) Birefringence (Δn)
Using the value of the retardation in the thickness direction (R _th ) obtained in <5) Retardation>, it was calculated by the following formula.
Δn=[R _th /d (film thickness (thickness of laminate))]/1000
7) Film thickness (thickness of laminate)
The film thickness of the obtained resin thin film and the thickness of the resin thin film laminate were measured with a thickness gauge manufactured by Teclock Co., Ltd.

[1] Preparation Examples Preparation Example 1: Preparation of silica sol (GBL-M) In a 1000 mL round-bottomed flask, Nissan Chemical Industries, Ltd. methanol-dispersed silica sol: MA-ST-M 350 g (silica solid content concentration: 40.4 % by mass) and 419 g of γ-butyl lactone were added. Then, the flask was connected to a vacuum evaporator to reduce the pressure in the flask, and immersed in a hot water bath at about 35° C. for 20 to 50 minutes to obtain silica sol (GBL-M) in which the solvent was replaced by γ-butyl lactone from methanol. 560.3 g was obtained (silica solid content concentration: 25.25% by mass).

[2] Synthetic Examples Synthetic Example 1: Synthesis of Polyimide A (PI-A) 25.61 g (0.08 mol) of TFMB was placed in a 250 mL three-necked reaction flask equipped with nitrogen inlet/outlet, mechanical stirrer and condenser. ) was inserted. Then 173.86 g of GBL was added and stirring was started. Immediately after the diamine was completely dissolved in the solvent, stirred BODAxx 10 g (0.04 mol), CBDA 7.84 g (0.04 mol) and GBL 43.4 g were added and heated to 140° C. under nitrogen. . 0.348 g of 1-ethylpiperidine was then added into the solution and heated to 180° C. for 7 hours under nitrogen. Finally heating was stopped and the reaction solution was diluted to 10% and kept stirring overnight. The polyimide was purified by adding the polyimide reaction solution to 2000 g of methanol, stirring for 30 minutes, and then filtering the polyimide solids. The polyimide solid was then stirred in 2000 g of methanol for 30 minutes, and the polyimide solid was filtered. This polyimide solid purification procedure of stirring and filtering was repeated three times. Methanol residues in the polyimide were removed by drying in a vacuum oven at 150° C. for 8 hours, finally obtaining 31.16 g of dry polyimide A. The yield of polyimide A (PI-A) was 74% (Mw=169,802, Mn=55,308).

[3] Preparation of release layer forming composition and resin thin film forming composition, and production of resin thin film laminate (1)
Example 1: Formation of Peeling Layer At room temperature, 1 g of the polyimide (PI-A) of Synthesis Example 1 was dissolved in a GBL solvent so as to have a concentration of 8% by mass. A forming composition was obtained. After that, the composition is coated on a glass support substrate, baked in an air atmosphere at a temperature of 50° C. for 30 minutes, 140° C. for 30 minutes, and 200° C. for 60 minutes, and then baked at 300° C. for 60 minutes. did. In this way, a transparent polyimide film as a release layer was formed on the glass supporting substrate. Its optical and thermal properties are shown in Table 1.

Example 2 Formation of Release Layer Using the release layer-forming composition prepared in Example 1, the composition was coated on a glass support substrate and subjected to heating in an air atmosphere at a temperature of 50° C. for 30 minutes, at 140° C. for 30 minutes and After baking at 200° C. for 60 minutes, a transparent polyimide film as a release layer was obtained on a glass supporting substrate in the same manner as in Example 1, except that baking was further performed at 400° C. for 60 minutes. Its optical and thermal properties are shown in Table 1.

Example 3: Preparation of a composition for forming a resin thin film At room temperature, 1 g of the polyimide (PI-A) of Synthesis Example 1 was dissolved in a GBL solvent so as to have a concentration of 10% by mass. did. The filtrate was then added to 9.241 g of silica sol (GBL-M) (18-23 nm _SiO2 nanoparticles dispersed in GBL at 25.25%) and mixed for 30 minutes, then held stationary for a period of time. It was maintained overnight to obtain a composition for forming a resin thin film.
This composition for forming a resin thin film was coated on a glass support substrate, and under an air atmosphere at a temperature of 50°C for 30 minutes, 140°C for 30 minutes and 200°C for 60 minutes, and under a vacuum atmosphere of -99 kpa, It was baked at 280° C. for 60 minutes to obtain a resin thin film. Table 1 shows the optical and thermal properties of the obtained resin thin film.

Example A: Production of Resin Thin Film Laminate A The composition for forming a resin thin film prepared in Example 3 was coated on the release layer obtained in Example 1, and heated at 50°C for 30 minutes in an air atmosphere for 140 minutes. C. for 30 minutes, 200.degree. C. for 60 minutes, and a vacuum atmosphere of -99 kpa at 280.degree. C. for 60 minutes to obtain a resin thin film (polyimide A/silica sol composite resin thin film).
After that, the peeling layer and the resin thin film formed on the glass supporting substrate were separated (peeled) from the glass supporting substrate by mechanical cutting, and a resin thin film laminate A was obtained.
Table 1 shows the optical and thermal properties of the resin thin film laminate A.

5 and 6 show cross-sectional views (cross-section TEM) of the resin thin film laminate A, FIG. 7 shows (a) the surface (resin thin film side) of the resin thin film laminate A, and (b) the interface between the release layer and the resin thin film. , and (c) Raman IR spectra of the rear surface (release layer side), respectively. FIG. 6(a) is an enlarged view of the vicinity of "mixing" in FIG. 5, and FIG. 6(b) shows the component composition of each layer constituting the laminate, [001] being the intermediate layer, [ 002] indicates a resin thin film (polyimide+SiO ₂ ), and [003] indicates a release layer (DBL).
According to the cross-section TEM of FIGS. 5 and 6, the formation of an intermediate layer having a thickness of about 300 nm was confirmed at the interface between the formed release layer and the resin thin film.
Further, as shown in the Raman IR spectrum of FIG. 7, the IR spectrum of the interface between the peeling layer and the resin thin film (b) is almost identical in shape to the IR spectrum of the back surface (c), and the interface is considered to be derived from at least the peeling layer. The result was that

Example B: Production of Resin Thin Film Laminate B In the same procedure as in Example A, except that the composition for forming a resin thin film prepared in Example 3 was coated on the release layer obtained in Example 2, a resin A thin film laminate B was obtained.

8 and 9 show cross-sectional views (cross-section TEM) of the resin thin film laminate B, FIG. 10 shows the resin thin film laminate B (a) surface (resin thin film side), and (c) Raman IR spectra of the back surface (release layer side), respectively. FIG. 9(a) is an enlarged view of the vicinity of the interface in FIG. 8, and FIG. 9(b) shows the component composition of each layer constituting the laminate. [002] indicates a resin thin film (polyimide + SiO ₂ ).
According to the cross-section TEM of FIGS. 8 and 9, the interface between the formed release layer and the resin thin film is clearly separated compared to Example A, and the thickness of the intermediate layer in this case is very thin, about 1 nm or less. Met.
Further, as shown in the Raman IR spectrum of FIG. 10, the IR spectrum of the interface between (b) the peeling layer and the resin thin film almost matches the shape of the IR spectrum of (c) the back surface, and the interface is considered to be derived from the peeling layer. result.

Schematic cross-sectional views of the resin thin film laminates A and B obtained in the above examples are shown in FIGS.
As shown in FIG. 2, the resin thin film laminates A and B consist of a release layer (L II), an intermediate layer (L III), a resin thin film (polyimide A/silica sol composite resin thin film) ( L.
It was confirmed that they had a laminated structure in the order of I). Then, as shown in FIG. 3 , resin thin film laminates A and B were obtained by separating (peeling) these laminated structures from the supporting substrate (G1). 2 and 3, element layers such as electrodes are indicated by LIV.
Here, the release layer (L II), the resin thin film (polyimide A / silica sol composite resin thin film) (L
I) and the intermediate layer formed therebetween are considered to have the polymer network structure shown in FIG. This network means that the two polymers and the nanosilica are bound together by van der Waals forces or hydrogen bonds, thereby increasing the adhesion between the resin film and the release layer. The intermediate layer can be obtained not only from the release layer but also from the resin film. This is because the upper surface of the release layer may be partially dissolved by the solvent contained in the resin thin film-forming composition during the formation of the resin thin film. As a result, the intermediate layer can be obtained by re-reacting (thermally imidizing) the release layer and the resin thin film.

As shown in Table 1, the resin thin film laminate A obtained by the production method of the present invention has a low coefficient of linear expansion [ppm/° C.] (50 to 200° C.), and light transmission at 400 nm and 550 nm after curing. It was confirmed that the rate [%] was high, the yellowness represented by the CIE b* value was small, and the retardation was suppressed to a low value.

Further, the resin thin film laminate A of the present invention obtained in the above example does not break even when held with both hands and bent at an acute angle (about 30 degrees), and has high flexibility required for flexible display substrates. Was.

[4] Manufacture of resin thin film laminate (2)
Using the release layer forming composition prepared in <Example 1: Formation of release layer> and the resin thin film forming composition prepared in <Example 3: Preparation of resin thin film forming composition>, the following procedure was performed. to manufacture a resin thin film laminate.
(a) Preparation of release layer-forming composition containing cross-linking agent To the release layer-forming composition prepared in <Example 1: Formation of release layer>, CYMEL (registered trademark) 303 (manufactured by allnex) was added to the composition. A composition for forming a release layer containing a cross-linking agent was prepared by mixing so that the mass of the polyimide (PI-A) contained in the product was 30 phr.
(b) Preparation of a composition for forming a resin thin film containing a cross-linking agent To the composition for forming a resin thin film prepared in <Example 3: Preparation of a composition for forming a resin thin film>, CYMEL303 is added to the polyimide contained in the composition ( PI-A) and silica sol (GBL-M) were mixed in an amount of 30 phr based on the total mass to prepare a composition for forming a resin thin film containing a cross-linking agent.
(i) After forming a release layer on a glass substrate using the release layer forming composition, a resin thin film was formed on the release layer using the resin thin film forming composition.
(ii) After forming a release layer on a glass substrate using the release layer-forming composition, a resin thin film was formed on the release layer using the cross-linking agent-containing composition for forming a resin thin film. .
(iii) After forming a release layer on a glass support substrate using the composition for forming a release layer containing a cross-linking agent, a resin thin film was formed on the release layer using the composition for forming a resin thin film.
(iv) After forming a release layer on a glass support substrate using the composition for forming a release layer containing a cross-linking agent, a thin resin film is formed on the release layer using the composition for forming a resin thin film containing a cross-linking agent. formed.
After forming the resin thin film, the release layer and the resin thin film were peeled together from the glass supporting substrate by mechanical cutting, and the peelability was evaluated according to the following criteria.
<Peelability evaluation>
◎: Can be completely separated (peeled off) from the glass support substrate (almost 100%)
△: difficult to separate from the glass support substrate (5 to 50%)
×: Cannot be separated from the glass support substrate (<5%)

In each example, the firing conditions were 120° C. for 20 minutes, 140° C. for 20 minutes, 200° C. for 30 minutes, and 250° C. for 60 minutes in an air atmosphere.
Table 2 shows the results obtained.

As shown in Table 2, when either the release layer forming composition or the resin thin film forming composition contains a cross-linking agent, the resin thin film laminate can be easily peeled from the glass support substrate. was confirmed.

Claims (14)

A method for manufacturing a resin thin film laminate,
A step of forming a release layer on a supporting substrate using a release layer-forming composition containing a heat-resistant polymer A and an organic solvent;
forming a resin thin film on the release layer using a resin thin film-forming composition containing a heat-resistant polymer B and an organic solvent;
a step of peeling the release layer and the resin thin film together from the support substrate to obtain a resin thin film laminate,
The composition for forming a resin thin film further contains silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area measured by a nitrogen adsorption method, provided that
The heat-resistant polymer A and the heat-resistant polymer B are the same polymer,
The release layer-forming composition does not contain silicon dioxide particles,
Production method. 2. The production method according to claim 1, wherein said heat-resistant polymer A and heat-resistant polymer B are at least one polymer selected from polyimide, polybenzoxazole, polybenzobisoxazole, polybenzimidazole and polybenzothiazole. The heat-resistant polymer A and the heat-resistant polymer B are polyamic acids obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorine-containing aromatic diamine. 2. The production method according to claim 1, wherein the polyimide is obtained by imidization. The production method according to claim 3 , wherein the alicyclic tetracarboxylic dianhydride contains a tetracarboxylic dianhydride represented by formula (C1).

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).

(Wherein, multiple Rs independently represent a hydrogen atom or a methyl group, and * represents a bond.)] The production method according to claim 3 , wherein the fluorine-containing aromatic diamine contains a diamine represented by formula (A1).

(Wherein, B2 represents a divalent group selected from the group consisting of formulas (Y- ¹ ) to (Y-34).)

(In the formula, * represents a bond.) 4. The production method according to claim 3 , wherein the polyimide comprises monomer units represented by formula (1), monomer units represented by formula (2), or both.

2. The production method according to claim 1, wherein the composition for forming a resin thin film contains the heat-resistant polymer B and the silicon dioxide particles in a weight ratio of 7:3 to 3:7. 2. The manufacturing method according to claim 1, wherein said silicon dioxide particles have an average particle size of 60 nm or less. 2. The manufacturing method according to claim 1, wherein either the release layer forming composition or the resin thin film forming composition further contains a cross-linking agent. 2. A method according to claim 1, wherein curing is by heat or ultraviolet light. The adhesiveness between the peeling layer and the resin thin film is 0 to 5% peelable according to the CCJ series (JIS5400) classification, and the adhesiveness between the supporting substrate and the peeling layer is CCJ series (JIS5400 ) Classified as 50% or more peelable,
The manufacturing method according to claim 1. 2. The manufacturing method according to claim 1, wherein the release layer has a thickness of 100 [mu]m to 1 nm. 2. The manufacturing method according to claim 1, wherein the step of obtaining the resin thin film laminate is carried out using a method selected from knife cutting, mechanical separation and peeling. A method for manufacturing a flexible substrate by the manufacturing method according to any one of claims 1 to 13 .

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