JPWO2018225825A1 - Method for manufacturing flexible device substrate - Google Patents

Abstract

Excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, and excellent base film for flexible device substrates such as flexible display substrates that can be easily peeled from glass carriers. An object of the present invention is to provide a method for forming a resin thin film laminate that gives a plastic thin film having the above-mentioned performance. A method for producing a resin thin film laminate, comprising forming a release layer using a release layer forming composition containing a heat resistant polymer and an organic solvent on a supporting substrate, and then containing the heat resistant polymer and an organic solvent. A method of forming a resin thin film on the release layer using a composition for forming a resin thin film, and then peeling the release layer and the resin thin film as a unit from a supporting substrate, wherein nitrogen adsorption A method in which silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by the method are further contained substantially only in the resin thin film-forming composition.

Description

  The present invention relates to a method for producing a resin thin film laminate as a base film of a flexible device substrate, particularly a flexible printed circuit board such as a flexible display, and more specifically, a heat resistance obtained by laminating a transparent laminate on a supporting substrate. It relates to a polymer laminate.

In recent years, along with the rapid progress of electronics such as liquid crystal displays and organic electroluminescence displays, there has been a demand for thinner and lighter devices and more flexible devices.
In these devices, various electronic elements, such as thin film transistors and transparent electrodes, are formed on a glass substrate. By changing the glass material to a flexible and lightweight resin material, the device itself can be made thinner and It is expected to be lightweight and flexible.
As a candidate for such a resin material, attention has been paid to polyimide, and various reports on polyimide films have been made.

  For example, Patent Document 1 relates to an invention relating to a polyimide useful as a plastic substrate for a flexible display and a precursor thereof, and relates to tetracarboxylic acids containing an alicyclic structure such as cyclohexylphenyltetracarboxylic acid and various diamines. It is reported that the polyimide reacted with is excellent in transparency and heat resistance.

  Further, in Patent Document 2, by adding silica sol to polyimide, compatibility between the linear expansion coefficient, transparency, and low birefringence, which were the drawbacks of the conventional plastic substrate, is improved, and the plastic substrate for flexible display is improved. Can be expected to be applied to.

  On the other hand, when pursuing the advantages of the plastic substrate, handling and dimensional stability of the plastic substrate itself become a problem. That is, when the plastic substrate is made into a film and made thinner, the occurrence of wrinkles and cracks is prevented, and the positional accuracy in forming functional layers such as thin film transistors (TFTs) and electrodes and the functional layers after forming the functional layers are formed. 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 applied and fixed on glass, laser is irradiated from the glass side to force the plastic substrate having the functional layer from the glass. A method of separation (so-called laser lift-off process (method called EPLaR method (Electronics on Plastic by Laser Release)) has been proposed.

JP, 2008-231327, A International Publication No. 2015/152178

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 described above ensures the handleability and dimensional stability of a resin substrate by forming a functional layer on a plastic substrate fixed to glass by using glass as a supporting base material. Is. However, this EPLaR method (laser lift-off method) is a method of destroying the interface between the resin substrate and the supporting base material by laser irradiation when separating the resin substrate from the supporting base material. 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 or the like) is damaged, the resin substrate itself is greatly damaged, and the transmittance is lowered.

  The present invention has been made in view of the above circumstances, and is a resin thin film that provides a plastic thin film having excellent performance as a base film of a flexible device substrate such as a flexible display substrate that does not rely on the above laser lift-off technology. Providing a method for producing a laminated body, in particular, while maintaining excellent performance such as excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, its handleability and dimensional stability It is an object of the present invention to provide a method for manufacturing a resin thin film laminate (flexible device substrate) that can ensure the above.

  As a result of repeated intensive studies to achieve the above-mentioned object, the inventors of the present invention, when forming a resin thin film containing silicon dioxide in a heat resistant polymer in order to achieve both heat resistance and optical properties, were used as a support base material. By providing a peeling layer between them, a resin thin film laminate that is easily peeled from a supporting substrate while maintaining the features of excellent heat resistance, low retardation, excellent flexibility, and excellent transparency. The inventors have found that the above can be realized and completed the present invention.

That is, the first aspect of the present invention is a method for producing a resin thin film laminate,
A step of forming a release layer on the supporting substrate using the release layer-forming composition containing the heat resistant polymer A and an organic solvent,
A step of 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,
Including a step of peeling the resin thin film together with the peeling layer from the supporting substrate to obtain a resin thin film laminate,
The resin thin film-forming composition further contains silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by a nitrogen adsorption method,
The release layer-forming composition does not contain silicon dioxide particles, and relates to a production method.
As a second aspect, 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. The manufacturing method according to the first aspect.
As a fourth aspect, the heat-resistant polymer A and the heat-resistant polymer B are each independently a diamine containing a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a fluorine-containing aromatic diamine. The production method according to the first aspect, which is a polyimide obtained by imidizing a polyamic acid obtained by reacting with a component.
As a fifth aspect, the production method according to the fourth aspect, wherein the alicyclic tetracarboxylic dianhydride contains a tetracarboxylic dianhydride represented by the formula (C1).
[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).
(In the formula, plural R's each independently represent a hydrogen atom or a methyl group, and * represents a bond.)]
As a sixth aspect, the production method according to the fourth aspect, wherein the fluorinated aromatic diamine contains a diamine represented by the formula (A1).
(In the formula, B ² 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, the production method according to the fourth aspect, wherein the polyimide contains a monomer unit represented by the formula (1), a monomer unit represented by the 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, the production method according to the first aspect, wherein the silicon dioxide particles have an average particle diameter of 60 nm or less.
As a tenth aspect, the production method according to the first aspect, wherein either one of the release layer forming composition and the resin thin film forming composition further contains a crosslinking agent.
An eleventh aspect relates to the manufacturing method according to the first aspect, characterized in that the curing is performed by heat or ultraviolet rays.
As a twelfth aspect, the adhesiveness between the peeling layer and the resin thin film is 0 to 5% peelable in CCJ series (JIS5400) classification, and the adhesiveness between the supporting base material and the peeling layer is Is capable of 50% peeling according to CCJ series (JIS5400) classification, and relates to the manufacturing method according to the first aspect.
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, the manufacturing method according to the first aspect is characterized in that 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 viewpoints.

According to the method for producing a resin thin film laminate according to one aspect of the present invention, since the resin thin film laminate can be easily peeled from the supporting substrate, a low linear expansion coefficient, excellent heat resistance, low retardation, excellent flexibility. The resin thin film laminate can be easily manufactured with good reproducibility without impairing performance such as property.
The resulting resin thin film laminate has a low linear expansion coefficient, high transparency (high light transmittance, low yellowness), low retardation, and is excellent in flexibility, and therefore flexible devices, particularly flexible displays. It can be suitably used as a substrate.
Such a method for producing a resin thin film laminate according to the present invention is a flexible device which is required to have characteristics such as high flexibility, low linear expansion coefficient, high transparency (high light transmittance, low yellowness), and low retardation. It is possible to sufficiently deal with the progress in the field of substrates for use, especially substrates for flexible displays.

It is a figure showing each step of the manufacturing method of the present invention. It is a schematic diagram (cross section) of a layered product obtained by a manufacturing method of the present invention. G1 represents a supporting base material, L II represents a peeling layer, L I represents a resin thin film, and L IV represents an electrode layer formed on the resin thin film. It is a schematic diagram of the method of peeling the laminated body obtained by the manufacturing method of this invention from a support base material. It is a figure showing the structure of the peeling layer, the resin thin film, and the intermediate | middle layer in the laminated body obtained by the manufacturing method of this invention. 3 is a cross-sectional photograph (cross section TEM) of the laminate obtained in Example A. It is a figure which shows the cross-section photograph (cross section TEM) (a) of the laminated body obtained in Example A, and the component composition (b) of each layer. 3 is a Raman IR spectrum of a peeling layer, a resin thin film and its interface in the laminate obtained in Example A. 5 is a cross-sectional photograph (cross section TEM) of the laminate obtained in Example B. It is a figure which shows the cross-section photograph (cross section TEM) (a) of the laminated body obtained in Example B, and the component composition (b) of each layer. 3 is a Raman IR spectrum of a peeling layer, a resin thin film and its interface in the laminate obtained in Example B.

Hereinafter, the present invention will be described in detail.
The method for producing a resin thin film laminate of the present invention comprises a step of forming a release layer on a supporting substrate using a composition for forming a release layer containing a heat resistant polymer A and an organic solvent, and then a heat resistant polymer B and an organic solvent. A resin thin film forming composition containing a resin thin film is formed on the release layer, and the release layer and the resin thin film are removed together (as an integral body) from the supporting substrate to form a resin thin film laminate. When the body is obtained, 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 resin thin film forming composition. Is the way to do it. In order to exert the effect of the present invention, it is important that the silicon dioxide particles are substantially contained only in the resin thin film-forming composition and not substantially contained in the release layer-forming composition. ..
In the present invention, "substantially free of" silicon dioxide particles means that silicon dioxide particles are not contained except for random mixing in the preparation process of the composition, and even if mixed, It means that the content of the heat-resistant polymer B in the release layer-forming composition is smaller than the content of silicon dioxide particles in the heat-resistant polymer A of the resin thin film-forming composition. The content of silicon dioxide particles in the case where the release layer-forming composition is tentatively mixed with silicon dioxide particles is, specifically, 5% of the content of silicon dioxide particles to the heat resistant polymer A of the resin thin film-forming composition. It is preferably less than.
Hereinafter, first, regarding the composition for forming a release layer and the composition for forming a resin thin film used in the method for producing a resin thin film laminate, each component constituting these will be described.

[Heat resistant polymer (A and B)]
The release layer forming composition and the resin thin film forming composition used in the present invention include 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, heat resistant polymer A and heat resistant polymer A). Polymer B is collectively referred to as a heat resistant polymer).
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 a specific polyimide described below in particular, that is, a polyamic obtained by reacting a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic acid dianhydride component and a diamine component containing a fluorine-containing aromatic diamine. A polyimide obtained by imidizing an acid is preferable.
In the present specification, the heat-resistant polymer is a polymer having a weight loss of 5% or less at a temperature of 350 ° C or higher.

[Polyimide]
The polyimide preferably used in the present invention imidizes 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. The resulting polyimide.
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 is preferable that it contains a diamine to be used.

[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).
(In the formula, plural R's each independently represent a hydrogen atom or a methyl group, and * represents a bond.)

(In the formula, B ² 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 the formulas (X-1), (X-4), (X-6) and (X-7). Preferably, the compound is
Further, among the diamines represented by the above (A1), B ² in the formula is preferably a compound represented by the formula (Y-12) or (Y-13).
As a suitable example, a polyimide obtained by imidizing a polyamic acid obtained by reacting a tetracarboxylic acid dianhydride represented by the above formula (C1) and a diamine represented by the above formula (A1) will be described later. A monomer unit represented by the formula (2) is included.

In order to obtain a resin thin film laminate having a low linear expansion coefficient, low retardation and high transparency, which is the object of the present invention, and having excellent flexibility, with respect to the total number of moles of the tetracarboxylic dianhydride component. Then, the alicyclic tetracarboxylic dianhydride, for example, the tetracarboxylic dianhydride represented by the formula (C1) is preferably 90 mol% or more, more preferably 95 mol% or more, In particular, all (100 mol%) is optimally tetracarboxylic dianhydride represented by the above formula (C1).
Similarly, in order to obtain a resin thin film laminate having the above-mentioned low linear expansion coefficient, low retardation and high transparency, and excellent flexibility, a fluorine-containing aromatic group is used for all moles of the diamine component. The diamine, for example, the diamine represented by the formula (A1), is preferably 90 mol% or more, more preferably 95 mol% or more. Further, 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 the above formula (1), those represented by the formula (1-1) or (1-2) are preferable, and those represented by the formula (1-1) are more preferable.

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

As the monomer unit represented by the above formula (2), those represented by the formula (2-1) or (2-2) are preferable, and those represented by the 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), it is represented by the formula (1) in a molar ratio in the polyimide chain. The ratio of the monomer unit represented by the formula (2) is preferably 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 the tetracarboxylic dianhydride represented by the above formula (C1) and a diamine component containing the diamine represented by the formula (A1). In addition to the monomer units derived from, for example, the monomer units represented by the above formulas (1) and (2), other monomer units may be contained. The content ratio of the other monomer units is arbitrarily determined as long as the characteristics 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 acid dianhydride component containing the tetracarboxylic acid 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 unit represented by the formula (1) or the monomer unit represented by the formula (2), or the monomer unit 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% with respect to the total number of moles of the monomer unit represented by.

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

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

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

  In the polyimide used in the present invention, each monomer unit is bonded in any order.

As a preferred example, a polyimide having a monomer unit represented by the above formula (1) is a bicarboxylic [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 to imidize the resulting polyamic acid.
When the polyimide used in the present invention has a monomer unit represented by the above formula (2), the polyimide is 1,2,3,4-cyclobutanetetracarboxylic dianhydride as a tetracarboxylic dianhydride component. It is obtained by polymerizing a compound and a diamine represented by the following formula (4) as a diamine component in an organic solvent and imidizing the obtained polyamic acid.
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 formula (1) and the formula (2). The polyimide containing each monomer unit is a tetracarboxylic dianhydride component, in addition to the above tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and a diamine component represented by the following formula: It is obtained by polymerizing the diamine represented by (4) in an organic solvent and imidizing the obtained 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 may be mentioned.
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. 2,2'-bis (trifluoromethyl) benzidine or 3,3'-bis (trifluoromethyl) benzidine represented by the following formula (4-2) is preferably used, and particularly 2,2'- Preference is given to using bis (trifluoromethyl) benzidine.

Further, the polyimide used in the present invention contains the alicyclic tetracarboxylic dianhydride component containing the tetracarboxylic dianhydride represented by the above formula (C1) and the diamine represented by the formula (A1). In addition to the monomer unit derived from the diamine component, for example, the monomer unit represented by the formula (1) and the monomer unit represented by the formula (2), another monomer unit represented by the formula (3) is added. When having, the polyimide containing each monomer unit represented by Formula (1), Formula (2), and Formula (3) is a tetracarboxylic dianhydride component of the above-mentioned 2 types of tetracarboxylic dianhydride. In addition, a tetracarboxylic acid dianhydride represented by the following formula (5), a diamine represented by the above formula (4) as a diamine component, and a diamine represented by the following formula (6) in an organic solvent. It is obtained by polymerizing and polyimidic acid obtained by imidization.

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

Specifically, as the tetracarboxylic dianhydride represented by the formula (5), pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-Benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyl ether tetracarboxylic acid dianhydride, 3,3 ', 4,4'-diphenyl sulfone tetracarboxylic acid dianhydride 4,4 ′-(hexafluoroisopropylidene) diphthalic acid 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 acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentane Tetracarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride, etc. Alicyclic tetracarboxylic dianhydride; and aliphatic tetracarboxylic dianhydride such as 1,2,3,4-butanetetracarboxylic dianhydride, but are not limited thereto.
Among these, tetracarboxylic dianhydride in which A in the formula (5) is a tetravalent group represented by any of the formulas (A-1) to (A-4) is preferable, 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 preferable compound.

Examples of the diamine represented by the 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 Fats such as 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, and 1,9-nonamethylenediamine Group diamines are included, but are not limited to.
Among these, aromatic diamines in which B in the formula (6) is a divalent group represented by any of the formulas (B-1) to (B-11) are preferable, 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 [Also known as: 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 represented by the tetracarboxylic dianhydride component containing the alicyclic tetracarboxylic dianhydride represented by the formula (C1) and the formula (A1). It is obtained by imidizing a polyamic acid obtained by reacting with a diamine component containing a fluorine-containing aromatic diamine.
Specifically, for example, as a suitable example, bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dianhydride and optionally 1,2,3,4-cyclobutanetetracarboxylic acid An acid dianhydride, optionally a tetracarboxylic acid dianhydride component consisting of a tetracarboxylic acid dihydrate 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 consisting of the diamine component represented by 6) in an organic solvent to imidize the resulting polyamic acid.
The reaction from the above two components to polyamic acid is advantageous in that it can be relatively easily proceeded in an organic solvent and that by-products are not generated.

  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 further the molecular weight of the polyimide obtained by imidization. Although it is one, the tetracarboxylic acid dianhydride component can be usually about 0.8 to 1.2 with respect to the diamine component 1, for example, about 0.9 to 1.1, preferably 0. It is about 95 to 1.02. Similar to the usual polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the polyamic acid produced.

The organic solvent used in the reaction of the tetracarboxylic dianhydride component and the diamine component is not particularly limited as long as it does not adversely affect the reaction and the generated polyamic acid is dissolved. 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, dimethyl sulfoxide, tetra Methyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, isopropyl alcohol, methoxymethyl pentanol, 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, dihex Sylether, 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 acetate mono Ethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, isopropyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate , Butyl 3-methoxypropionate, diglyme, and 4-hydroxy-4-methyl-2-pentanone, but are not limited to these. 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 used as a mixture with the above-mentioned solvent as long as the generated polyamic acid does not precipitate. Further, since water in the organic solvent inhibits the polymerization reaction and causes hydrolysis of the generated polyamic acid, it is preferable to use dehydrated and dried organic solvent as much as possible.

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

The temperature at the time of synthesizing the polyamic acid may be appropriately set in the range from the melting point to the boiling point of the above-mentioned solvent to be used, and for example, an arbitrary temperature of −20 ° C. to 150 ° C. can be selected, but −5 C. to 150.degree. C., usually about 0 to 150.degree. C., preferably about 0 to 140.degree.
The reaction time cannot be specified unconditionally because it depends on the reaction temperature and the reactivity of the raw material, but it is usually about 1 to 100 hours.
Further, 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 and uniform stirring is 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. It is also possible to perform the reaction at a high concentration in the initial stage and then add an organic solvent.

<Imidization of polyamic acid>
Examples of the method for imidizing the polyamic acid include thermal imidization in which the polyamic acid solution is heated as it is and catalytic imidization in which a catalyst is added to the polyamic acid solution.
The temperature at which the polyamic acid is thermally imidized in the solution is 100 ° C. to 400 ° C., preferably 120 ° C. to 250 ° C., and it is preferable to perform it while removing the water generated by the imidization reaction outside the system.

For chemical (catalytic) imidization of polyamic acid, a basic catalyst and an acid anhydride are added to a solution of polyamic acid, and the system is allowed to react in a temperature condition of -20 to 250 ° C, preferably 0 to 180 ° C. It can be performed by stirring.
The amount of the basic catalyst is 0.5 to 30 mol times, preferably 1.5 to 20 mol times, of the amic acid group of the polyamic acid, and the amount of the acid anhydride is 1 to 50 mols of the amic acid group of the polyamic acid. It is 2 times, preferably 2 to 30 times.

Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and 1-ethylpiperidine. Among them, pyridine and 1-ethylpiperidine have an appropriate basicity for proceeding the reaction. Therefore, it is preferable.
Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, acetic anhydride is preferable because purification after the reaction is facilitated.
The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, the reaction temperature, and the reaction time.

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

  In the present invention, after filtering the reaction solution, the filtrate may be used as it is, or may be diluted or concentrated to form a composition for forming a peeling layer, and a resin thin film prepared by further mixing silicon dioxide or the like described below therein. It may be a forming composition. Thus, when subjected to filtration, not only can the heat resistance of the resin thin film laminate obtained, the mixture of impurities that may cause deterioration of the flexibility or linear expansion coefficient characteristics can be reduced, and the release layer forming composition efficiently, and A resin thin film forming composition can be obtained.

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

<Recovery of polymer>
When the polymer component is recovered from the reaction solution of polyamic acid and polyimide and used, the reaction solution may be poured into a poor solvent to cause precipitation. Examples of the poor solvent 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 pouring it into a poor solvent can be collected by filtration and then dried at normal temperature or under reduced pressure at room temperature or by heating.
Further, by repeating the operation of re-dissolving the precipitated and recovered polymer in an organic solvent, re-precipitating and recovering it (reprecipitation recovery step) 2 to 10 times, impurities in the polymer can be reduced. At this time, it is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent because the efficiency of purification is further improved.

  The organic solvent that dissolves 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 Examples include ketones, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, and 4-hydroxy-4-methyl-2-pentanone. You may use these solvents in mixture of 2 or more types.

[Silicon dioxide]
Silicon dioxide (silica) used in the composition for forming a resin thin film of the present invention is not particularly limited, but silicon dioxide in a particle form, for example, an average particle diameter 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, still more preferably 5 nm to 35 nm, and further preferably 5 nm to 30 nm.
In the present invention, the average particle diameter of the silicon dioxide particles is the average particle diameter value calculated from the specific surface area value measured by the nitrogen adsorption method using the silicon dioxide particles.

Particularly in the present invention, colloidal silica having the above-mentioned average particle diameter can be preferably 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 and an organosilica sol obtained by substituting an organic solvent for water, which is a dispersion medium of the aqueous silica sol.
Alkoxysilanes such as methyl silicate and ethyl silicate are hydrolyzed and condensed in the presence of a catalyst (for example, ammonia, an organic amine compound, an alkali catalyst such as sodium hydroxide) in an organic solvent such as alcohol. The silica sol to be used, or an organosilica sol obtained by substituting the silica sol with another organic solvent can also be used.
Among these, in the present invention, it is preferable to use an organosilica sol in which the dispersion medium is an organic solvent.

Examples of the organic solvent in the above-mentioned 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 replacement can be performed by a usual method such as a distillation method or an ultrafiltration method.
The viscosity of the above organosilica sol is about 0.6 mPa · s to 100 mPa · s at 20 ° C.

Examples of commercially available organosilica sol include, for example, trade name MA-ST-S (methanol-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.), trade name 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 ( Co., Ltd.), trade name IPA-ST-UP (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name IPA-ST-L (isopropanol-dispersed silica sol, manufactured by Nissan Chemical Industry Co., 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 Industry Co., Ltd., trade name EAC-ST (ethyl acetate dispersed silica sol, manufactured by Nissan Chemical Industry Co., Ltd.), trade name PMA-ST (propylene glycol monomethyl ether acetate dispersed silica sol, Nissan Chemical Industry ( Co., 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.), trade name MIBK-ST (methyl isobutyl ketone-dispersed silica sol, manufactured by Nissan Chemical Industries, Ltd.) and the like can be mentioned, but not limited thereto.
In the present invention, silicon dioxide, for example, the silicon dioxide as mentioned in the above products used as the organosilica sol may be used as a mixture of two or more kinds.

[Crosslinking agent]
The release layer forming composition and the resin thin film forming composition used in the present invention may further contain a crosslinking agent. When using a cross-linking agent in the present invention, it is preferable to blend only one of the peeling layer forming composition or the resin thin film forming composition, and above all, only in the resin thin film forming composition. It is preferable to incorporate a crosslinking agent.
The cross-linking agent used here is a compound composed only of hydrogen atom, carbon atom and oxygen atom, or a compound composed only of these atom and nitrogen atom, and has a hydroxy group, an epoxy group and 1 to 10 carbon atoms. 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, not only the resin thin film laminate excellent in solvent resistance and suitable for a flexible device substrate is reproducibly provided, but also the storage stability is further improved. A resin thin film forming composition 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 crosslinking agent is preferably from the viewpoint of reproducibly realizing the solvent resistance of the obtained resin thin film laminate. It is 3 or more and 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. Examples thereof include 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, but from the viewpoint of ensuring the solubility of the cross-linking agent in a solvent and obtaining a resin thin film laminate having high flatness, 1 or 2 is preferred.
When two or more ring structures are present, the ring structures may be condensed with each other, and an alkane having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a propane-2,2-diyl group, or the like. 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 has a cross-linking ability, and is not particularly limited as long as it dissolves in the solvent used, solvent resistance of the resin thin film laminate obtained, the solubility of the cross-linking agent itself in an organic solvent, Considering availability and price, it is preferably about 100 to 500, more preferably about 150 to 400.

  The cross-linking agent may further have a group that can be derived from a hydrogen atom, a carbon atom, a nitrogen atom and an oxygen atom, such as a ketone group and an ester group (bond).

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

In the above formula, each A ¹ and A ² independently of each other represents an alkane-diyl group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, and a propane-2,2-diyl group. Among them, 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 one another 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.
Of these, considering the availability and cost of the cross-linking agent, X is preferably an epoxy group in the formulas (K1) and (K5), and has 1 to 5 carbon atoms in the formulas (K2) and (K3). An alkoxy group is preferred, and a hydroxy group is preferred in formula (K4).

In the formula (K4), each n represents the number of — (A ¹ -X) groups bonded to the benzene ring, and is independently an integer of 1 to 5, preferably 2 to 3, and more preferably It is 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) are aryl compounds, heteroaryl compounds, skeleton compounds such as cyclic amines having the same ring structure as those of these compounds, epoxyalkyl halide compounds, It can be obtained by reacting with an alkoxy halide compound or the like by a carbon-carbon coupling reaction or an N-alkylation reaction, or by hydrolyzing the resulting alkoxy site.

As the cross-linking agent, a commercially available product may be used, or one synthesized by a known synthesis method may be used.
As commercial products, CYMEL (registered trademark) 300, the same 301, the same 303LF, the same 303ULF, the same 304, the same 350, the same 3745, the same XW3106, the same MM-100, the same 323, the same 325, the same 327, the same 328, Same 385, Same 370, Same 373, Same 380, Same 1116, Same 1130, Same 1133, Same 1141, Same 1161, Same 1168, Same 3020, Same 202, Same 203, Same 1156, Same MB-94, Same MB-. 96, MB-98, 247-10, 651, 658, 683, 688, 1158, MB-14, MI-12-I, MI-97-IX, U-65. , Same UM-15, same U-80, same U-21-511, same U-21-510, same U-216-8, same U-227-8, same U-1050-10, same U-1052. -8, the same U-1054, the same U-610, the same U-640, the same UB-24-BX, the same UB-26-BX, the same UB-90-BX, the same UB-25-BE, and the same 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, NF2000, etc. (all manufactured by Allnex); TEPIC (registered trademark) V, and S, HP, L, PAS, VL, and UC (all manufactured by Nissan Chemical Industries, Ltd.), TM-BIP-A (manufactured by Asahi Organic Materials 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, HP-820 (DIC Corporation), TG-G (Shikoku Chemical Industry Co., Ltd.), etc. are mentioned.

Specific preferred examples of the cross-linking agent will be given below, but the cross-linking agent is not limited thereto.

  The blending amount of the cross-linking agent cannot be specified unconditionally because it is appropriately determined depending on the type of the cross-linking agent, etc., but is usually relative to the mass of the polyimide contained in the release layer-forming composition, or a resin thin film formation. 50 mass% or less, preferably 100 mass% or less, with respect 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 obtained resin thin film laminate and suppressing the weakening. It is 0.1 mass% or more, preferably 1 mass% or more, from the viewpoint of ensuring the solvent resistance of the obtained resin thin film laminate.

[Organic solvent]
The release layer forming composition and the resin thin film forming composition used in the present invention contain an organic solvent. The organic solvent is not particularly limited, and examples thereof include those similar to the specific examples of the reaction solvent used when preparing the above 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. The organic solvents may be used alone or in combination of two or more.
Among these, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and γ-butyrolactone are preferable in consideration of obtaining a resin thin film laminate having high flatness with good reproducibility.

[Release layer forming composition]
The release layer-forming composition used in the present invention is a composition containing the heat-resistant polymer and an organic solvent, and optionally a crosslinking agent, and substantially containing silicon dioxide as described above. It does not. The solid content and viscosity of the release layer-forming composition are in accordance with the resin thin film-forming composition described below.

[Composition for forming resin thin film]
The composition for forming a resin thin film used in the present invention is a composition containing the heat resistant polymer, silicon dioxide, and an organic solvent, and optionally a crosslinking 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 compounding ratio of the heat resistant polymer and the silicon dioxide is preferably a heat resistant polymer: silicon dioxide = 10: 1 to 1:10, more preferably 8 by mass ratio. : 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. When the solid content concentration is less than 0.5% by mass, the film-forming efficiency is low in producing a resin thin film, and the viscosity of the resin thin film-forming composition is low, so that a coating film having a uniform surface can be obtained. Hateful. When the solid content concentration exceeds 30% by mass, the viscosity of the resin thin film-forming composition becomes too high, which may also deteriorate film forming efficiency and lack surface uniformity of the coating film. The solid content (solid content concentration) as used herein means the total mass of components other than the organic solvent, and even liquid monomers and the like 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, and the purpose is to obtain a resin thin film having a thickness of about 5 to 50 μm with good reproducibility. In this case, it is usually about 500 to 50,000 mPa · s at 25 ° C., preferably about 1,000 to 20,000 mPa · s.

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

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

The composition for forming a resin thin film is, for example, a polyimide and a silicon dioxide obtained by the above-described method as a heat resistant polymer, a cross-linking agent if necessary, and other components as necessary (various organic or inorganic low molecule or It can be obtained by dissolving a polymer compound) in the above-mentioned organic solvent. Alternatively, silicon dioxide may be added to the reaction solution after the preparation of the polyimide, and the organic solvent may be further added if desired.
As described above, when the crosslinking 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 a release layer and the resin contained in the composition for forming a resin thin film are the same as described above from the viewpoint of not affecting the characteristics and the like. Preferably. Further, 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 it satisfies these preferable conditions. Therefore, in the method of the present invention, for example, first, after preparing the composition for forming a release layer, silicon dioxide particles are added as described above to a part of the composition for forming a release layer, and if desired, an organic layer is formed. 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 producing resin thin film laminate>
[Step of forming release layer]
This step is a step of forming a release layer on the supporting substrate using the above-described release layer-forming composition.
Specifically, the release layer-forming composition is applied onto a supporting substrate, dried and heated to remove the organic solvent, and thus has excellent heat resistance, low retardation, excellent flexibility, and is transparent. It is possible to obtain a peeling layer that can be easily peeled from a supporting substrate by at least one method selected from the group consisting of cutting with a knife, mechanical separation and simultaneous peeling, while maintaining excellent performance that is also excellent in property. Therefore, a flexible device substrate can be obtained.

Examples of the supporting substrate include plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy, melamine, triacetyl cellulose, ABS, AS, norbornene-based resin, etc.), metal, stainless steel (SUS), wood, Examples include 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 base material to be applied is glass or a silicon wafer, and since the release layer obtained shows good release properties, it is glass. More preferable. The linear expansion coefficient of the supporting base material to be applied is preferably 40 ppm / ° C. or less, more preferably 30 ppm / ° C. or less, from the viewpoint of the warpage of the supporting base material after coating.

  The method for applying the release layer-forming composition to the supporting substrate is not particularly limited, and examples thereof include cast coating method, spin coating method, blade coating method, dip coating method, roll coating method, bar coating method. Examples thereof include die coating method, ink jet method, printing method (letterpress, intaglio, planographic printing, screen printing, etc.), and these can be appropriately used according to the purpose.

The heating temperature is preferably 500 ° C. or lower, more preferably 450 ° C. or lower. However, when the temperature exceeds 300 ° C., a problem of yellowing may occur. In this case as well, the ratio of the thickness of the release layer to the total thickness of the resin thin film laminate obtained by the production method of the present invention is as follows. As mentioned above, it is sufficiently small and has little influence on the characteristics. Further, when the resin thin film forming composition is applied onto the formed release layer, the higher the final baking temperature is, the smaller the proportion of the release layer dissolved in the resin thin film forming composition becomes. 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. On the other hand, when the temperature is 300 ° C. or less, a part of the peeling layer becomes a resin thin film forming composition. By melting, the boundary between the peeling layer and the resin thin film becomes a gradation shape, but in any case, the effect of the present invention is exhibited.
Further, 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 more than 175 ° C to 450 ° C for 30 minutes to 2 hours. As described above, by heating at a temperature of two or more steps of drying the solvent and promoting the molecular orientation, it is possible to exhibit the low thermal expansion characteristics with good reproducibility.
In particular, the applied release layer-forming composition is heated at 40 ° C. to 100 ° C. for 5 minutes to 2 hours, then at 100 ° C. to 175 ° C. for 5 minutes to 2 hours, and then in the range of 175 ° C. to 450 ° C. It is preferable to heat at the internal temperature for 5 minutes to 2 hours.
Examples of equipment used for heating include a hot plate and an oven. The heating atmosphere may be under air or under an inert gas such as nitrogen, may be under normal pressure or under reduced pressure, and different pressure may be applied in each stage of heating. May be.

  Further, in this step, a fine structure (intermediate layer) may be formed on the surface of the release layer by a coating technique from the viewpoint of further enhancing the adhesiveness between the release layer and the resin thin film formed thereafter. In that 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 applying the composition for forming the release layer, or during the stepwise heating thereafter.

  The thickness of the release layer is appropriately determined within the range of about 1 nm to 200 μm in consideration of the type of flexible device, but in order to exert the effect of the present invention, it is at least thicker than the diameter of silica particles. It is necessary. In particular, assuming 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 can be obtained by adjusting the thickness of the coating film before heating. To form a peeling layer.

[Resin thin film forming process]
This step is a step of forming a resin thin film on the release layer using the resin thin film forming composition of the present invention described above. It can be said that this step is a step of forming a resin thin film laminate including a release layer and a resin thin film formed thereon on a supporting base material.
Specifically, by applying the thin film-forming composition on the release layer formed on the supporting substrate, and drying and heating to remove the organic solvent, high heat resistance and high transparency are obtained. And, it is possible to obtain a resin thin film having a proper flexibility, a proper linear expansion coefficient and a small retardation.
Further, in this step, a part of the peeling layer is dissolved by the organic solvent contained in the resin thin film-forming composition, whereby the resin thin film and the peeling layer are brought into close contact with each other, and the adhesion between them 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 are in accordance with the respective conditions described in the step of forming the release layer.

In the resin thin film laminate formed on the supporting base material in this way, in order to realize easy peeling from the supporting base material, the adhesive force of the resin thin film to the peeling layer is more than that of the peeling layer to the supporting base material. Is also 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 base material and the peeling layer are It is preferable that the adhesiveness between the two is 5 (50% or more peelable) in the CCJ series (JIS5400) classification. The CCJ series is defined as a classification from 0 to 5, where 0 classification means that 0% of the square area can be peeled off, 1 classification represents 1-5% of the square area and 2 classification. 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. The above means that each can be peeled off. In other words, under the conditions of the cross-cut test according to JIS K5400, the number of peeled squares of the resin thin film with respect to the peeling layer is classification 0 to 2, and the number of peeled squares of the peeling layer with respect to the supporting base material is classification 5. Is preferred.

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

As described above, according to the method of the present invention, since the adhesion between the release layer and the resin thin film is stronger than the adhesion between the release layer and the supporting substrate, the release 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 may 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 peeling layer is preferably 1 to 35% with respect to the thickness (100%) of the resin thin film laminate.

The resin thin film laminate obtained in one preferred embodiment of the present invention can realize high transparency such that the light transmittance at a wavelength of 400 nm is 75% or more.
Furthermore, the resin thin film laminate can have a low coefficient of linear expansion of, for example, 60 ppm / ° C. or less at 50 ° C. to 200 ° C., particularly 10 ppm / ° C. to 35 ppm / ° C., and for example, at 200 ° C. to 250 ° C. The coefficient of linear expansion can be as low as 80 ppm / ° C. or less, particularly 15 ppm / ° C. to 55 ppm / ° C., and the dimensional stability upon heating is excellent.
In particular, the resin thin film laminate is represented by the product of birefringence (difference between two in-plane orthogonal refractive indexes) and film thickness (thickness of the 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 refractive index in the thickness direction) when viewed from the cross section in the thickness direction, respectively, are determined by the film thickness (of the laminated body). The thickness direction retardation R _th represented as the average value of the two retardations obtained by multiplying 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, for example, 660 nm or less, for example, 10 nm when the average film thickness (average thickness of the laminate) is 15 μm to 40 μm. ˜660 nm, in-plane retardation R ₀ less than 4, eg 0.3-3.9, birefringence Δn less than 0.02, eg very low 0.0003-0.019. ..
As described above, according to the production method of the present invention, retardation can be reduced in the obtained resin thin film laminate.

  The resin thin film laminate obtained by using the manufacturing method of the present invention described above satisfies each condition required as a base film of a flexible display substrate because it has the above-mentioned characteristics, and thus it is a base film of a flexible display substrate. Can be used particularly preferably as That is, the present invention is suitable as a method for manufacturing a flexible device substrate.

An example of manufacturing a flexible device using the manufacturing method of the present invention is shown in FIG.
As shown in FIG. 1, first, a release layer is formed on a supporting substrate, and a resin thin film is formed on the release layer to obtain a resin thin film laminate. Then, after forming a functional layer on the resin thin film laminate, these are combined and peeled off to obtain a flexible device.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples.

The 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 apparatus and conditions used for the preparation of samples and the analysis and evaluation of physical properties are as follows.
1) Measurement of number average molecular weight and weight average molecular weight The number average molecular weight (hereinafter abbreviated as Mn) and the weight average molecular weight (hereinafter abbreviated as Mw) of a polymer are measured by a device: Showdex GPC-101 manufactured by Showa Denko KK, It was measured under the conditions of column: 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, a thin film (or a laminated body) is cut into a size having a width of 5 mm and a length of 16 mm, and the temperature is first raised at 10 ° C./min and heated to 50 to 350 ° C. (first heating). 50 ° C. to 200 ° C. of the second heating when the temperature is lowered at 10 ° C./min and cooled to 50 ° C. and then the temperature is raised at 10 ° C./min to 50 to 420 ° C. (second heating). It was determined by measuring the value of the coefficient of linear expansion (CTE [ppm / ° C]) at ° C. A load of 0.05 N was applied through the first heating, the cooling and the second heating.
3) 5% weight loss temperature (Td _5% )
The 5% weight loss temperature (Td _5% [° C]) is TGA Q500 manufactured by TA Instruments, and about 5 to 10 mg of the thin film (or laminated body) is heated in nitrogen to 50 to 800 ° C at 10 ° C / min. Then, it was determined by measuring.
4) Light transmittance (transparency) (T _308nm , T _400nm , T _550nm ) and CIE b value (CIE b ^* )
Light transmittance at a wavelength of 308 nm, 400 nm and _{550nm (T 308nm, T 400n m} , T 550nm [%]) and CIE b value (CIE ^{b *)} using the Nippon Denshoku Industries Co., Ltd. SA4000 spectrometer, The measurement was performed at room temperature using air as a reference.
5) Retardation (R _th , R ₀ ).
The thickness direction retardation (R _th ) and the 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 the in-plane retardation (R ₀ ) are calculated by the following formulas.
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 called a slow axis, Ny is also called a fast axis)
Nz: Refractive index in thickness (vertical) direction with respect to plane d: Film thickness (thickness of laminated body)
ΔNxy: difference between two in-plane refractive indices (Nx-Ny) (birefringence)
ΔNxz: Difference between in-plane refractive index Nx and thickness direction refractive index Nz (birefringence)
ΔNyz: Difference between in-plane refractive index Ny and thickness direction refractive index Nz (birefringence)
6) Birefringence (Δn)
The value of the retardation in the thickness direction (R _th ) obtained by the above <5) Retardation> was used and calculated by the following formula.
Δn = [R _th / d (film thickness (thickness of laminated body)) / 1000
7) Film thickness (thickness of laminated body)
The 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 example Preparation example 1: Preparation of silica sol (GBL-M) In a 1000 mL round bottom flask, Nissan Chemical Industries Ltd. methanol dispersion silica sol: MA-ST-M 350g (silica solid content concentration: 40.4). Mass%) and 419 g of γ-butyl lactone. Then, the flask was connected to a vacuum evaporator to reduce the pressure inside the flask, and the flask was immersed in a warm water bath at about 35 ° C. for 20 to 50 minutes to change the solvent from methanol to γ-butyrolactone silica sol (GBL-M). 560.3 g was obtained (silica solid content concentration: 25.25 mass%).

[2] Synthetic Example Synthetic Example 1: Synthesis of Polyimide A (PI-A) In a 250 mL reaction three-necked flask equipped with a nitrogen inlet / outlet, a mechanical stirrer and a condenser, TFMB 25.61 g (0.08 mol) ) Was put. Then, 173.86 g of GBL was added and stirring was started. Immediately after the diamine was completely dissolved in the solvent, 10 g (0.04 mol) of stirred BODAxx, 7.84 g (0.04 mol) of CBDA and 43.4 g of GBL were added and heated to 140 ° C. under nitrogen. .. Then, 0.348 g of 1-ethylpiperidine was added to 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 reaction solution was added to 2000 g of methanol and stirred for 30 minutes, and then the polyimide solid was filtered to purify the polyimide. Then, the polyimide solid was stirred in 2000 g of methanol for 30 minutes, and the polyimide solid was filtered. The purification procedure of stirring and filtering this polyimide solid was repeated three times. The methanol residue in the polyimide was removed by drying in a vacuum oven at 150 ° C. for 8 hours, finally obtaining 31.16 g of dried 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 release layer At room temperature, 1 g of the polyimide (PI-A) of Synthesis Example 1 dissolved in a GBL solvent to 8% by mass was slowly pressure filtered through a 1 μm filter to obtain a release layer. A forming composition was obtained. Then, the composition was coated on a glass supporting substrate, baked at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and then 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 The release layer-forming composition prepared in Example 1 was used to coat it on a glass supporting substrate, under an air atmosphere at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes, and 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 the baking was performed at 200 ° C. for 60 minutes and then at 400 ° C. for 60 minutes. Its optical and thermal properties are shown in Table 1.

Example 3: Preparation of resin thin film-forming composition At room temperature, 1 g of the polyimide (PI-A) of Synthesis Example 1 was dissolved in a GBL solvent to a concentration of 10% by mass and slowly filtered under pressure through a 5 μm filter. did. The filtrate was then added to 9.241 g of silica sol (GBL-M) (18-23 nm SiO ₂ nanoparticles dispersed in GBL at 25.25%) and mixed for 30 minutes, then allowed to stand still. It was maintained overnight to obtain a resin thin film forming composition.
This composition for forming a resin thin film is coated on a glass supporting substrate, and under an air atmosphere, at a temperature of 50 ° C. for 30 minutes, at 140 ° C. for 30 minutes and at 200 ° C. for 60 minutes, and under a vacuum atmosphere of −99 kpa, A resin thin film was obtained by baking at 280 ° C. for 60 minutes. Table 1 shows the optical and thermal characteristics 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 at 140 ° C. for 140 minutes. The resin thin film (polyimide A / silica sol composite resin thin film) was obtained by baking at 30 ° C. for 30 minutes, at 200 ° C. for 60 minutes, and under a vacuum atmosphere of −99 kpa at 280 ° C. for 60 minutes.
Then, the peeling layer and the resin thin film formed on the glass supporting base material were separated (peeled) from the glass supporting base material by mechanical cutting to obtain a resin thin film laminate A.
Table 1 shows the optical and thermal characteristics of the resin thin film laminate A.

5 and 6 are cross-sectional views (cross section TEM) of the resin thin film laminate A, and FIG. 7 is (a) surface (resin thin film side) of the resin thin film laminate A, (b) interface between the peeling layer and the resin thin film. , And (c) the Raman IR spectra of the back 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, where [001] is the intermediate layer and [ 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 the intermediate layer was confirmed at the interface between the formed peeling layer and the resin thin film, and the thickness thereof was about 300 nm.
Further, as shown in the Raman IR spectrum of FIG. 7, the IR spectrum of the interface between the (b) peeling layer and the resin thin film has a shape substantially identical to the IR spectrum of the back surface (c), and it is considered that the interface originates from at least the peeling layer. The result was

Example B: Production of resin thin film laminate B A resin was prepared 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 thin film laminate B was obtained.

8 and 9 are 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), (b) the interface between the peeling layer and the resin thin film, 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, where [001] is the release layer (DBL), [002] represents a resin thin film (polyimide + SiO ₂ ).
According to the cross-section TEM of FIGS. 8 and 9, the interface between the formed peeling layer and the resin thin film is clearly separated as compared with Example A, and the thickness of the intermediate layer in this case is about 1 nm or less, which is very thin. Met.
Further, as shown in the Raman IR spectrum of FIG. 10, the IR spectrum of the interface between the peeling layer and the resin thin film (b) has almost the same shape as the IR spectrum of the back surface (c), and it is considered that the interface originates from the peeling layer. It was a result.

2 and 3 are schematic cross-sectional views of the resin thin film laminates A and B obtained in the above examples.
As shown in FIG. 2, the resin thin film laminates A and B include a release layer (L II), an intermediate layer (L III), a resin thin film (polyimide A / silica sol composite resin thin film) (on a supporting substrate (G1) ( L
It was confirmed to have a laminated structure in the order of I). Then, as shown in FIG. 3, the resin thin film laminates A and B were obtained by separating (peeling) these laminated structures from the supporting base material (G1). 2 and 3, element layers such as electrodes are indicated by L IV.
Here, the peeling layer (L II), the resin thin film (polyimide A / silica sol composite resin thin film) (L
I) and the intermediate layer formed between them are considered to have the polymer network structure shown in FIG. 4, respectively. This network means that the two polymers and the nanosilica are bonded to each other by Van der Waals force or hydrogen bond, which strengthens the adhesive force between the resin thin film and the release layer. The intermediate layer can be obtained not only from the release layer but also from the resin thin film. This is because the upper surface of the release layer can be partially dissolved by the solvent contained in the resin thin film-forming composition when the resin thin film is formed. Thus, the intermediate layer can be obtained by the reaction (thermal imidization) of the peeling layer and the resin thin film again.

  As shown in Table 1, the resin thin film laminate A obtained by the production method of the present invention has a low linear expansion coefficient [ppm / ° C] (50 to 200 ° C), and also has a 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 examples does not crack even when held with both hands and bent at an acute angle (about 30 degrees), and has the high flexibility required for a flexible display substrate. Was.

[4] Production of resin thin film laminate (2)
Using the release layer forming composition prepared in <Example 1: Release layer formation> and the resin thin film forming composition prepared in <Example 3: Preparation of resin thin film forming composition>, the following procedure is performed. To produce a resin thin film laminate.
(A) Preparation of release layer-forming composition containing a crosslinking agent CYMEL (registered trademark) 303 (manufactured by Allnex Co.) was added to the composition for release layer formation prepared in <Example 1: Formation of release layer> above. The polyimide (PI-A) contained in the product was mixed so as to be 30 phr with respect to the mass thereof to prepare a composition for forming a release layer containing a crosslinking agent.
(B) Preparation of resin thin film forming composition containing cross-linking agent CYMEL 303 is added to the resin thin film forming composition prepared in <Example 3: Preparation of resin thin film forming composition> PI-A) and silica sol (GBL-M) were mixed in an amount of 30 phr with respect to the total mass thereof to prepare a composition for forming a resin thin film containing a crosslinking agent.
(I) After forming a peeling layer on a glass support base material using the said composition for peeling layer formation, the resin thin film was formed on the said peeling layer using the composition for resin thin film formation.
(Ii) A peeling layer was formed on a glass support substrate using the peeling layer-forming composition, and then a resin thin film was formed on the peeling layer using the cross-linking agent-containing resin thin film-forming composition. ..
(Iii) After forming a peeling layer on a glass supporting substrate using the above-mentioned composition for forming a cross-linking agent and for forming a peeling layer, a resin thin film was formed on the peeling layer using the above composition for forming a resin thin film.
(Iv) After forming a release layer on a glass supporting substrate using the composition for forming a cross-linking agent and for forming a release layer, and then using the composition for forming a resin thin film and forming a resin thin film on the release layer. Formed.
After forming the resin thin film, the peeling 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) from the glass supporting substrate (almost 100%)
Δ: difficult to separate from glass supporting substrate (5 to 50%)
×: Cannot be separated from the glass supporting 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.
The obtained results are shown in Table 2.

  As shown in Table 2, when either one of the peeling layer forming composition or the resin thin film forming composition contains a crosslinking agent, the resin thin film laminate can be easily peeled from the glass supporting substrate. Was confirmed.

Claims (15)

A method of manufacturing a resin thin film laminate,
A step of forming a release layer on the supporting substrate using the release layer-forming composition containing the heat resistant polymer A and an organic solvent,
A step of 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,
Including a step of peeling the resin thin film together with the peeling layer from the supporting substrate to obtain a resin thin film laminate,
The resin thin film-forming composition further contains silicon dioxide particles having an average particle diameter of 100 nm or less calculated from the specific surface area value measured by a nitrogen adsorption method,
The release layer-forming composition is characterized in that it does not contain silicon dioxide particles,
Production method. The manufacturing method according to claim 1, wherein the heat-resistant polymer A and the heat-resistant polymer B are the same polymer. 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. Manufacturing method. The heat-resistant polymer A and the heat-resistant polymer B each independently react with a tetracarboxylic dianhydride component containing an alicyclic tetracarboxylic dianhydride and a diamine component containing a fluorine-containing aromatic diamine. The method according to claim 1, which is a polyimide obtained by imidizing the obtained polyamic acid. The production method according to claim 4, wherein the alicyclic tetracarboxylic dianhydride contains a tetracarboxylic dianhydride represented by the formula (C1).
[In the formula, B ¹ represents a tetravalent group selected from the group consisting of formulas (X-1) to (X-12).
(In the formula, plural R's each independently represent a hydrogen atom or a methyl group, and * represents a bond.) The production method according to claim 4, wherein the fluorine-containing aromatic diamine includes a diamine represented by the formula (A1).
(In the formula, B ² represents a divalent group selected from the group consisting of formulas (Y-1) to (Y-34).)
(In the formula, * represents a bond.) The manufacturing method according to claim 4, wherein the polyimide contains a monomer unit represented by the formula (1), a monomer unit represented by the formula (2), or both monomer units.
The production method according to claim 1, wherein the resin thin film-forming composition contains the heat-resistant polymer B and the silicon dioxide particles in a mass ratio of 7: 3 to 3: 7. The manufacturing method according to claim 1, wherein the silicon dioxide particles have an average particle diameter of 60 nm or less. The manufacturing method according to claim 1, wherein either one of the composition for forming the release layer or the composition for forming the resin thin film further contains a crosslinking agent. The manufacturing method according to claim 1, wherein the curing is performed by heat or ultraviolet rays. The adhesiveness between the release layer and the resin thin film is 0 to 5% peelable according to the CCJ series (JIS5400) classification, and the adhesiveness between the supporting base material and the release layer is CCJ series (JIS5400). ) 50% or more of peeling is possible according to classification,
The manufacturing method according to claim 1. The manufacturing method according to claim 1, wherein the release layer has a thickness of 100 μm to 1 nm. The manufacturing method according to claim 1, wherein the step of obtaining the resin thin film laminate is carried out by using a method selected from cutting with a knife, mechanical separation and peeling. A flexible substrate manufactured by the manufacturing method according to any one of claims 1 to 14.