WO2015012339A1

WO2015012339A1 - Laminate, method for processing same, and method for manufacturing flexible device

Info

Publication number: WO2015012339A1
Application number: PCT/JP2014/069526
Authority: WO
Inventors: 朗繁田; 吉田　猛; 祐己山田; 達弥森北; 山田　宗紀; 寿史朗江口; 雅弘細田; 良彰越後
Original assignee: ユニチカ株式会社
Priority date: 2013-07-24
Filing date: 2014-07-24
Publication date: 2015-01-29
Also published as: JPWO2015012339A1; TW201509682A; TWI654090B; CN105408115B; CN105408115A; JP6363077B2

Abstract

　The objective of the present invention is to provide a laminate having good adhesion between a polyimide film and an inorganic substrate, and also allowing easy and quick separation of the polyimide film from the inorganic substrate. The present invention provides a laminate having an inorganic substrate, and a polyimide film formed on the inorganic substrate, wherein the laminate has the following characteristics: (1) the polyimide film is a layered film containing a polyimide resin layer (A) and a polyimide resin layer (B), the entire surface of the polyimide resin layer (A) contacting the inorganic substrate, and a part of the polyimide resin layer (B) formed on the surface of the polyimide resin layer (A) contacting the inorganic substrate; (2) the adhesive strength between the polyimide resin layer (A) and the inorganic substrate is 2N/cm or less; (3) the adhesive strength between the polyimide resin layer (B) and the inorganic substrate exceeds 2N/cm; and (4) the polyimide resin layer (B) contacting the inorganic substrate is hygroscopically treated and made capable of separating from the inorganic substrate.

Description

LAMINATE, PROCESSING METHOD THEREOF, AND METHOD FOR PRODUCING FLEXIBLE DEVICE

The present invention relates to a laminate in which a polyimide film is formed on an inorganic substrate, a processing method thereof, and a manufacturing method of a flexible device. The laminate and the treatment method of the present invention are useful, for example, when manufacturing a flexible device or a flexible wiring board in which an electronic element is formed on the surface of a flexible substrate.

Conventionally, in the field of electronic devices such as flat panel displays (FPD) such as liquid crystal displays (LCD), plasma display panels (PDP), organic EL displays (OLED), and electronic paper, mainly from inorganic materials such as glass substrates. A substrate in which an electronic element is formed on a substrate (inorganic substrate) is used. However, since the inorganic substrate is rigid and lacks flexibility, there is a problem that it is difficult to be flexible.

Therefore, a method of using an organic polymer material such as polyimide having flexibility and heat resistance as a substrate has been proposed. That is, a technology in which a heat-resistant polyimide film having flexibility is laminated on an inorganic substrate used as a carrier, and the polyimide film is used as a substrate for forming an electronic device or a wiring substrate has been put into practical use. . Here, for example, when a glass substrate excellent in light transmittance is used as an inorganic substrate, an inspection process when forming an electronic element or wiring board is facilitated, and an electronic element is placed on an existing glass substrate. There is an advantage that the equipment for producing the flexible device to be formed can be used as it is.

In such an inorganic substrate laminated with a polyimide film, since the inorganic substrate is used as a substrate for a carrier, an electronic element is formed on the surface of the polyimide film, and finally the polyimide film is peeled from the inorganic substrate. There is a need. However, from the viewpoint of preventing the polyimide film from being peeled off from the inorganic substrate in the step of forming the electronic element, the polyimide film must be firmly adhered to the inorganic substrate, so that peeling is not easy. As a method for industrially performing this peeling, for example, a method of irradiating a polyimide interface in contact with a glass substrate with laser light has been proposed (for example,

Patent Documents

1 and 2 and Non-Patent Document 1). Also, a method of heating the polyimide interface in contact with the glass substrate with Joule heat without using laser light (Patent Document 3), a method of induction heating (Patent Document 4), and a method of irradiating flash light from a xenon lamp ( A method for peeling is proposed by Patent Document 5) and the like. In such a method, only one layer is in contact with the inorganic substrate at the peeling interface between the inorganic substrate and the polyimide film. However, these methods have a problem that the process is complicated and takes a long time, and the equipment is expensive, which is not only expensive but also difficult to reuse the inorganic substrate.

Therefore, as a peeling method instead of the above method, Patent Document 6 proposes a method of improving the peelability of the polyimide laminate by leaving it in pressurized steam for a long time. Patent Document 7 proposes a method of immersing in water in order to improve the peelability of the polyimide laminate. These methods utilize the fact that the stress generated when the polyimide film rapidly expands due to water absorption or moisture absorption from the polyimide film surface acts on the interface between the polyimide film and the inorganic substrate. As a result, the adhesion at this interface is reduced and the peelability is improved. Even in such a method, at the peeling interface between the inorganic substrate and the polyimide laminate, only one kind of layer is in contact with the inorganic substrate. Furthermore, in Patent Document 8, a patterned adhesive layer is formed on a glass substrate, a flexible substrate layer such as polyimide is formed on both the adhesive layer surface and the glass plate surface, and then the adhesive layer surface. A method has been proposed in which only the upper flexible substrate layer is separated and then the flexible substrate layer is peeled off from the glass substrate.

Special table 2007-512568 gazette JP 2013-73001 A JP 2012-189974 A JP 2014-86451 A JP 2014-120664 A JP 2000-196243 A US Pat. No. 7,759,983 German published patent 102012102131A1

However, in the method using moisture absorption or water absorption, since moisture absorption or water absorption from the polyimide film surface is used, for example, a gas barrier layer (layer for blocking the transmission of water vapor or oxygen on the polyimide film surface, Thus, when an OLED or the like is used to prevent deterioration of an electronic element formed on a polyimide film, moisture absorption and water absorption are not sufficiently performed, and a sufficient peelability improvement effect is obtained. There was no problem. Moreover, in the method of leaving for a long time in the pressurized water vapor | steam as disclosed by patent document 6, there existed a problem that a hydrolysis of a polyimide advanced and film deterioration occurred. Further, in the method using a patterned adhesive layer as disclosed in Patent Document 8, the process is complicated, and the adhesion when forming a member such as an electronic element and the glass substrate after forming the member are reduced. It was difficult to achieve both of the peelability. Furthermore, it is difficult to peel the adhesive layer from the glass substrate, and it is difficult to recycle the glass substrate.

Therefore, the present invention solves the above problems, and provides a laminate that has good adhesion between a polyimide film and an inorganic substrate, and can easily and easily peel the polyimide film from the inorganic substrate in a short time. Objective.

In the present invention, the adhesion between the polyimide film and the inorganic substrate is good, and even if a gas barrier layer is formed on the polyimide film, the polyimide film can be peeled from the inorganic substrate easily and in a short time. The purpose is to provide a laminate.

In the present invention, the adhesion between the polyimide film and the inorganic substrate is good, and even if a member such as an electronic element or wiring is formed on the polyimide film, the polyimide film can be easily and quickly formed. It aims at providing the laminated body which can peel from an inorganic substrate.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have a specific configuration of a laminate (hereinafter sometimes abbreviated as “laminate”) in which a polyimide film is formed on an inorganic substrate. As a result, the inventors have found that the above problems can be solved, and have completed the present invention.

That is, the present invention has the following purpose.
A laminate having an inorganic substrate and a polyimide-based film formed on the inorganic substrate, the laminate having the following characteristics:
(1) The polyimide film is a laminated film including a polyimide resin layer A and a polyimide resin layer B, the entire surface of the polyimide resin layer A is in contact with the inorganic substrate, and is on the surface of the polyimide resin layer A. Part of the formed polyimide resin layer B is in contact with the inorganic substrate;
(2) The adhesive strength between the polyimide resin layer A and the inorganic substrate is 2 N / cm or less;
(3) The adhesive strength between the polyimide resin layer B and the inorganic substrate is more than 2 N / cm;
(4) The polyimide resin layer B in contact with the inorganic substrate can be peeled from the inorganic substrate by moisture absorption treatment.

The laminate as described above, wherein the inorganic substrate is a glass substrate.

The laminate as described above, wherein a gas barrier layer is formed on the surface of the polyimide resin layer B.

A method for treating a laminate, wherein the laminate is subjected to moisture absorption treatment to peel the polyimide film from the inorganic substrate.

The method for treating a laminate, wherein the moisture absorption treatment is a treatment in which the laminate is held under an environment of a temperature of 100 ° C. or less and a relative humidity of 70% or more and then dehumidified by decompression.

After forming one or more members selected from electronic elements and wiring (hereinafter may be abbreviated as “members such as electronic elements”) on the surface of the polyimide film of the laminate, the laminate is subjected to moisture absorption treatment. By removing the polyimide film provided with the above member from the inorganic substrate, and then cutting and removing the portion of the polyimide resin layer B in contact with the inorganic substrate, a flexible device is obtained. A manufacturing method of a flexible device.

On the surface of the polyimide film of the laminate, one or more members selected from electronic elements and wirings are formed, and a predetermined portion of the polyimide film provided with the members is cut, the polyimide film After dividing the member formation region portion and the polyimide resin layer B portion in contact with the inorganic substrate, the member formation region portion in the polyimide film is peeled off to obtain a flexible device, and to the inorganic substrate. A method for producing a flexible device, wherein the remaining polyimide resin layer B is peeled off from the inorganic substrate by moisture absorption treatment.

The method for producing a flexible device, wherein the moisture absorption treatment is a treatment of dehumidification by reducing pressure after holding the laminate in an environment of a temperature of 100 ° C. or less and a relative humidity of 70% or more.

The laminate of the present invention is easily flexible because the polyimide film can be easily peeled off from the inorganic substrate by, for example, moisture absorption treatment, despite the fact that the polyimide film is firmly adhered to the inorganic substrate. Devices and flexible wiring boards can be manufactured. Moreover, even when a gas barrier layer is formed on the surface of the polyimide film, good peelability can be easily obtained by moisture absorption treatment.

(A) is the schematic diagram (sectional drawing) of the laminated body of one embodiment which concerns on this invention, (B) is the outline when the laminated body of FIG. 1 (A) is seen from upper direction in a figure. It is a sketch. (A) is the schematic diagram (sectional drawing) of the laminated body of one embodiment which concerns on this invention which has a gas barrier layer, (B) looked at the laminated body of FIG. 2 (A) from the upper direction in the figure. It is a schematic sketch at the time. (A) And (B) is the schematic diagram (sectional drawing) of the polyimide-type film for demonstrating the method of manufacturing a flexible substrate by the processing method 1 of a laminated body using the laminated body of FIG. 1 (A). . (A) And (B) is the schematic diagram (sectional drawing) of the polyimide-type film for demonstrating the method to manufacture a flexible substrate by the processing method 1 of a laminated body using the laminated body of FIG. 2 (A). . (A) And (B) is the schematic diagram (sectional drawing) of the polyimide-type film for demonstrating the method to manufacture a flexible substrate by the processing method 2 of a laminated body using the laminated body of FIG. 1 (A). . (A) And (B) is the schematic diagram (sectional drawing) of the polyimide-type film for demonstrating the method of manufacturing a flexible substrate by the processing method 2 of a laminated body using the laminated body of FIG. 2 (A). .

Hereinafter, the present invention will be described in detail.

[Laminate]
The laminate of the present invention has a flexible substrate layer made of a polyimide film on an inorganic substrate. The inorganic substrate used here is not limited to a glass substrate, a metal substrate such as copper or aluminum, or a ceramic substrate such as alumina, but a glass substrate excellent in light transmittance is preferably used. As the glass substrate, for example, soda lime glass, borosilicate glass, non-alkali glass or the like can be used, and among these, the non-alkali glass substrate can be preferably used.

The thickness of the inorganic substrate is preferably 0.3 to 5.0 mm. If the thickness is less than 0.3 mm, the handling property of the substrate may be lowered. Moreover, productivity may fall when thickness is thicker than 5.0 mm. These inorganic substrates may be subjected to a surface treatment for controlling adhesion to the polyimide film layer, for example, a silane coupler treatment.

As shown in FIGS. 1A and 1B, a laminate 100 of the present invention has a polyimide film 2 laminated on an inorganic substrate 1. The polyimide film 2 is a laminated film including a polyimide resin layer A (21) and a polyimide resin layer B (22), and the entire surface of the polyimide resin layer A (21) is in contact with the inorganic substrate 1. A part of the polyimide resin layer B (22) formed on the surface of the polyimide resin layer A (21) is in contact with the inorganic substrate 1. FIG. 1A is a schematic view (cross-sectional view) of a laminate according to an embodiment of the present invention. FIG. 1B is a schematic sketch when the laminate of FIG. 1A is viewed from above in the drawing.

The entire surface of the polyimide resin layer A is in contact with the inorganic substrate, as shown in FIG. 1A, the polyimide resin layer A (21) is in contact with the inorganic substrate 1 over the entire surface. It means that.

A part of the polyimide resin layer B is in contact with the inorganic substrate, as shown in FIGS. 1A and 1B, the polyimide resin layer B (22) is polyimide resin layer A (21). Formed on the outer peripheral region 210 of the polyimide resin layer A (21) on the entire surface of the substrate and the surface of the inorganic substrate 1, and the polyimide resin layer B (22) is formed at the outer edge portion 220 (shaded portion in the drawing) of the inorganic substrate. It means that it is in direct contact with 1. When the polyimide resin layer B is not formed, and even when the polyimide resin layer B is formed, if a portion thereof is not in contact with the inorganic substrate, the adhesion of the polyimide film to the inorganic substrate 1 is reduced. For this reason, when a member such as an electronic element is formed on the polyimide film before the polyimide film is peeled off from the inorganic substrate, the polyimide film is peeled off and the working efficiency is lowered. When the entire surface of the polyimide resin layer B is in contact with the inorganic substrate, that is, when the polyimide resin layer A is not formed, the peelability of the polyimide film from the inorganic substrate is lowered. Specifically, after forming a member such as an electronic element on a polyimide film having a gas barrier layer formed on the surface, when the polyimide film is peeled off from the inorganic substrate, the polyimide film portion immediately below the member is sufficiently moisture-absorbing. Therefore, it is difficult to peel the polyimide film from the inorganic substrate.

The area of the polyimide resin layer B is preferably 110% or more, more preferably 120% or more with respect to the area of the polyimide resin layer A, from the viewpoint of adhesion of the polyimide film to the inorganic substrate. Preferably, it is more preferable to set it as 150% or more. The upper limit of the area of the polyimide resin layer B is not particularly limited, but from the viewpoint of reducing material loss, the area of the polyimide resin layer B is usually 200% with respect to the area of the polyimide resin layer A. Or less, preferably 180% or less, and more preferably 160% or less. The area of the polyimide resin layer A is the area of the formation region of the polyimide resin layer A on the surface of the inorganic substrate 1 and is equal to the area of the broken line region 211 in FIG. The area of the polyimide resin layer B refers to the area of the polyimide resin layer A and the outer peripheral region 210 of the polyimide resin layer A (21) on which the polyimide resin layer B is directly formed on the surface of the inorganic substrate 1. This is the sum of the area and is equal to the area of the region 22 showing the polyimide resin layer B in FIG.

In FIG. 1B, the polyimide resin layer A (21) and the polyimide resin layer B (22) have a square shape, but the polyimide film 2 peeled off in the laminate of the present invention. It may have any shape depending on the application. The polyimide resin layer A and the polyimide resin layer B may have, for example, a circular shape or a rectangular shape. When the polyimide film 2 is used as a flexible substrate, the shape of the polyimide resin layer A and the polyimide resin layer B is usually square or rectangular.

In the polyimide resin layer B (22), the width W (see FIG. 1B) of the outer edge portion 220 that directly contacts the inorganic substrate 1 is usually 2 mm or more, particularly 2 mm or more and 100 mm or less. From the viewpoint of an even better balance between adhesiveness 2 and peelability, the thickness is preferably 3 mm or more and 80 mm or less, more preferably 4 mm or more and 50 mm or less. 1A and 1B, the outer edge 220 of the polyimide resin layer B (22) is directly connected to the inorganic substrate 1 over the entire circumference of the outer peripheral region 210 of the polyimide resin layer A (21). Although it is in contact, the outer edge 220 may not be in direct contact with the inorganic substrate 1 in a part of the outer peripheral region 210 as long as the polyimide film 2 has a desired adhesion before the moisture absorption treatment.

The adhesive strength of the polyimide resin layer A to the inorganic substrate is 2 N / cm or less, preferably 1 N / cm or less, and more preferably 0.5 N / cm or less. When the polyimide resin layer A has such an adhesive strength before the moisture absorption treatment of the present invention described later, good releasability between the polyimide resin layer A and the inorganic substrate can be ensured. If the adhesive strength of the polyimide resin layer A with the inorganic substrate exceeds 2 N / cm, it is difficult to peel the polyimide film from the inorganic substrate. The lower limit of the adhesive strength between the polyimide resin layer A and the inorganic substrate is not particularly limited, and the lower the better.

The adhesive strength of the polyimide resin layer B with the inorganic substrate is more than 2 N / cm, preferably 5 N / cm or more, and more preferably 7 N / cm or more. By having such an adhesive strength before the moisture absorption treatment of the present invention, which will be described later, the polyimide resin layer B can ensure good adhesion between the polyimide resin layer B and the inorganic substrate, Adhesiveness with the inorganic substrate of the whole polyimide film laminated and integrated can be ensured. If the adhesive strength of the polyimide resin layer B with the inorganic substrate is too low, the polyimide film is peeled off when a member such as an electronic element is formed on the polyimide film before the polyimide film is peeled off from the inorganic substrate. Work efficiency is reduced. The upper limit value of the adhesive strength of the polyimide resin layer B with the inorganic substrate is not particularly limited, but the contact strength is usually 20 N / cm or less, preferably 10 N / cm or less.

The polyimide resin layer B can be peeled from the inorganic substrate by moisture absorption treatment. Specifically, after the moisture absorption treatment described later, the polyimide resin layer B can be peeled off by a specific peeling method described later such as a method of peeling off from the end portion by hand. For example, the polyimide resin layer B has the following adhesive strength after the moisture absorption treatment. The adhesive strength of the polyimide resin layer B after the moisture absorption treatment with the inorganic substrate is usually 2 N / cm or less, preferably 1 N / cm or less, and more preferably 0.5 N / cm or less. Since the polyimide resin layer B is bonded to the inorganic substrate with such a low adhesive strength by the moisture absorption treatment, the polyimide film can be easily peeled from the inorganic substrate. If the adhesive strength of the polyimide resin layer B with the inorganic substrate exceeds 2 N / cm after the moisture absorption treatment, it is difficult to peel the polyimide film from the inorganic substrate. The lower limit value of the adhesive strength after the moisture absorption treatment of the polyimide resin layer B with the inorganic substrate is not particularly limited, and the lower the better.

The adhesive strength referred to in the present invention refers to a value measured by performing a 180 ° peel test on the adhesive strength between a polyimide resin layer and an inorganic substrate based on JIS K6854-2.

The polyimide resin layer A and the polyimide resin layer B constituting the polyimide film are formed by forming a polyimide resin into a film. The polyimide resin is a resin having an imide bond in the main chain, and specific examples include polyimide, polyamideimide, polyesterimide, etc., but are not limited thereto, and a resin having an imide bond in the main chain. Any resin can be used. These resins are usually used alone, but two or more kinds may be mixed and used. The polyimide resins constituting the polyimide resin layer A and the polyimide resin layer B are independently selected, and any polyimide resin is preferably used alone.

As the polyimide, it is possible to use a precursor type polyimide or a solvent soluble type polyimide which is obtained by thermally curing a polyimide precursor such as polyamic acid dissolved in a solvent, and a precursor type polyimide can be preferably used.

The polyimide resin preferably has 50 mol% or more of structural units derived from imide bonds (provided that all the structural units are 100 mol%).

Commercially available products may be used as the polyimide resin. That is, for example, “Uimide AR”, “Uimide AH”, “Uimide BH”, “Uimide CR”, “Uimide CH” (all manufactured by Unitika Ltd.) and U varnish A (manufactured by Ube Industries) Polyamic acid type varnish such as “Rika Coat SN-20” (manufactured by Shin Nippon Chemical Co., Ltd.), “Matrimid 5218” (manufactured by Huntsman), etc., dissolved in a solvent, polyimide soluble varnish, Viromax HR-11NN Polyamideimide varnish such as Toyobo Co., Ltd.) can be used.

The precursor-type polyimide is a polyimide precursor solution obtained by reacting approximately equimolar amounts of tetracarboxylic acid or dianhydride and diamine as raw materials in a solvent, and applying this, drying, thermosetting A polyimide layer can be obtained by (imidization).

The reaction temperature at the time of producing this polyimide precursor solution is preferably −30 to 60 ° C., more preferably −15 to 40 ° C. In this reaction, the order of addition of the monomer and the solvent is not particularly limited, and may be any order.

Examples of the tetracarboxylic acid or dianhydride thereof include pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 3, 3 ', 4,4'-diphenylsulfone tetracarboxylic acid, acid, 3,3', 4,4'-diphenyl ether tetracarboxylic acid, 2,3,3 ', 4'-benzophenone tetracarboxylic acid, 2,3,6 , 7-naphthalenetetracarboxylic acid, 1,4,5,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 3,3 ′, 4,4′-diphenylmethanetetracarboxylic acid, 2 , 2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 3,4,9,10 Tetracarboxyperylene, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] hexafluoropropane, 1, 2,3,4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, bicyclo [2,2,2] oct-7- En-2,3,5,6-tetracarboxylic acid and their dianhydrides can be used alone or as a mixture, but are not limited thereto.

Here, pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid or their dianhydrides are particularly preferably used.

Examples of the diamine include p-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4 '. -Diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,2-bis (anilino) ethane, diaminodiphenylsulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2,2 -Bis (p-aminophenyl) propane, 2,2-bis (p-aminophenyl) hexafluoropropane, 1,5-diaminonaphthalene, diaminotoluene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) )benzene, , 4'-bis (p-aminophenoxy) biphenyl, diaminoanthraquinone, 4,4'-bis (3-aminophenoxyphenyl) diphenylsulfone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis ( Anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino) tetradecafluoroheptane, 1,2-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine 1,5-pentadiamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,12-dodecanediamine, cis -1,4-diaminocyclohexane, trans-1,4-diaminocyclohex 1,4-diaminocyclohexane isomer mixture, cis-cis-4,4′-diaminodicyclohexylmethane, cis-trans-4,4′-diaminodicyclohexylmethane, trans-trans-4,4′-diaminodicyclohexylmethane 4,4′-diaminodicyclohexylmethane isomer mixture, cis-1,3-bis (aminoethyl) cyclohexane, trans-1,3-bis (aminoethyl) cyclohexane, 1,3-bis (aminoethyl) cyclohexane isomerism Body mixture, cis-trans-4,4′-methylenebis (2-methylcyclohexylamine), trans-trans-4,4′-methylenebis (2-methylcyclohexylamine), 4,4′-methylenebis (2-methylcyclohexyl) Amine ) Isomer mixture, cis-cis-4,4′-diaminodicyclohexylenepropane, cis-trans-4,4′-diaminodicyclohexylenepropane, 4,4′-diaminodicyclohexylenepropane, etc. However, it is not limited to these.

Here, p-phenylenediamine, 4,4′-diaminodiphenyl ether, and 2,2-bis [4- (4-aminophenoxy) phenyl] propane are particularly preferably used.

The solid content concentration of the polyimide precursor is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. This polyamic acid solution may be partially imidized.

The viscosity of the polyimide precursor solution of the present invention at 25 ° C. is preferably 1 to 150 Pa · s, more preferably 5 to 100 Pa · s.

The solvent used in the polyimide precursor solution is not limited as long as it is a solvent that dissolves the polyimide precursor, and examples thereof include amide solvents, ether solvents, and water-soluble alcohol solvents.

Specific examples of the amide solvent include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and the like.

Examples of ether solvents include 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol Monoethyl ether, tripropylene glycol monomethyl ether, polyethylene Glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether.

Examples of water-soluble alcohol solvents include methanol, ethanol, 1-propanol, 2-propanol, tert-butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, , 4-butadiol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, di- Acetone alcohol etc. are mentioned.

These solvents can be used as a mixture of two or more. Among these solvents, particularly preferred examples include N, N-dimethylacetamide and N-methyl-2-pyrrolidone as the sole solvent, and examples of the mixed solvent include N, N-dimethylacetamide and N—. Examples include combinations of methyl-2-pyrrolidone, N-methyl-2-pyrrolidone and methanol, N-methyl-2-pyrrolidone and 2-methoxyethanol, and the like.

The method for producing the polyimide resin layers A and B using the polyimide precursor solution will be described, but the following description is applied mutatis mutandis also in the case of using a polymer other than the polyimide described above as the polyimide resin. It is clear that the polyimide resin layers A and B can be produced.

In the production of polyimide resin layers A and B, first, “polyimide precursor solution A” for producing polyimide resin layer A and “polyimide precursor solution B” for producing polyimide resin layer B ( These may be abbreviated as “polyimide solution A” and “polyimide solution B”, respectively). Subsequently, the polyimide solution A is apply | coated on an inorganic board | substrate, and after drying, the polyimide solution B is apply | coated and dried on the surface of a dry coating film and an inorganic substrate. Thereafter, these coating films are collectively thermoset and imidized. Drying as used herein refers to reducing the amount of solvent in the polyimide precursor solution by means such as heating. At this time, it is preferable to remove the solvent until the solid content concentration in the coating film is 50% by mass or more and 90% by mass or less. By drying in this way, the adhesiveness of the interface of the polyimide resin layer A and the polyimide resin layer B is ensured, and it can laminate and integrate. Any device can be used for drying, and a hot air dryer is preferable, but infrared heating, electromagnetic induction heating, or the like may be used. A temperature range of 50 to 200 ° C. is suitable for drying. Moreover, the thermosetting here means the process of converting a polyimide precursor into a polyimide. A temperature range of 300 to 450 ° C. is suitable for thermosetting. When applying the polyimide solution B, the entire surface of the polyimide resin layer A is covered, and the area of the polyimide resin layer B is made larger than the area of the polyimide resin layer A, so that the layer configuration described above is obtained. Can do.

In order to obtain the adhesive strength of the polyimide-based resin layer A, for example, a higher fatty acid such as stearic acid or palmitic acid, or a release agent such as an amide or a metal salt thereof may be added to the polyimide precursor solution A. it can. Of these, stearic acid is preferred. The greater the compounding amount of the release agent, the smaller the adhesive strength of the polyimide resin layer. On the other hand, the smaller the compounding amount of the release agent, the greater the adhesive strength of the polyimide resin layer.

The compounding amount of the release agent in the polyimide precursor solution A is not particularly limited as long as the polyimide resin layer achieves a predetermined adhesive strength, and is usually added in an amount of 0.01 to 2% by mass relative to the polyimide mass. Is more preferable, and 0.1 to 1% by mass is more preferable. In this specification, the polyimide mass means the total polyimide mass in terms of polyimide contained in the polyimide precursor solution.

In order to obtain the adhesive strength of the polyimide resin layer A, an adhesion improver described later can be blended in the polyimide precursor solution A. The influence on the adhesive strength by the blending of the adhesion improver is the same as in the polyimide precursor solution B.

In the polyimide precursor solution B, an adhesion improver such as a silane coupler can be blended in the solution as necessary in order to obtain the adhesive strength. The silane coupler is not limited in its type such as amine, epoxy, and acrylic, but is preferably an amine. The greater the compounding amount of the adhesion improver, the greater the adhesive strength of the polyimide resin layer. On the other hand, the smaller the compounding amount of the adhesion improver, the smaller the adhesive strength of the polyimide resin layer.

As the compounding amount of the adhesion improver in the polyimide precursor solution B, it is preferable to add 0.05 to 0.5% by mass, more preferably 0.05 to 0.2% by mass, and more preferably to the polyimide mass. Preferably it is 0.1 to 0.2 mass%.

In the polyimide precursor solution B, in order to obtain the adhesive strength of the polyimide resin layer B, the above-described release agent can be blended. The influence on the adhesive strength by the blending of the release agent is the same as in the polyimide precursor solution A.

The polyimide precursor solutions A and B can be applied continuously or in single wafers.

Continuous coating can be carried out using a coating machine such as a die coater, lip coater, comma coater, gravure coater, reverse roll coater.

Continuous coating can also be performed using a coating machine such as a bar coater, a doctor blade coater, or a spin coater.

Here, continuous application is often accompanied by difficulty because the inorganic substrate is rigid, and therefore, application in sheet form is preferable from the viewpoint of industrial production.

The coating thickness of the polyimide resin layer A is preferably 0.5 to 10 μm and more preferably 1 to 5 μm after thermosetting.
Moreover, as the application thickness of the polyimide resin layer B, the thickness after thermosetting is preferably 5 to 200 μm, and more preferably 10 to 100 μm. The thickness of the polyimide resin layer B is the thickness of the entire polyimide film including the polyimide resin layer A, and is equal to the thickness of the outer edge portion 220.

As described above, in an electronic device using a polyimide-based film as a flexible substrate, it is common to provide a gas barrier layer in order to prevent water vapor or the like from entering an OLED light-emitting layer or the like. In the laminated body of this invention, this gas barrier layer can be provided in the part by which the polyimide-type resin layer A of the surface of the polyimide-type resin layer B is laminated | stacked (embedded). As the gas barrier layer, a film made of an inorganic oxide such as silicon oxide, aluminum oxide, silicon carbide, silicon oxycarbide, silicon carbonitride, silicon nitride, or silicon nitride oxide can be used, but a film made of silicon oxide is preferable. That's right. Examples of the method for forming these films include known methods such as sputtering, vacuum deposition, thermal CVD, plasma CVD, and photo CVD, but sputtering is preferred. The thickness of the gas barrier layer is preferably 10 to 100 nm, and more preferably 20 to 50 nm.

As shown in FIGS. 2A and 2B, the gas barrier layer 3 is provided on the surface of the polyimide resin layer B at a position (region) overlapping with the position of the polyimide resin layer A in the vertical direction. As shown in FIGS. 2A and 2B, the gas barrier layer 3 must be provided in the entire overlapping area with the polyimide resin layer A in the vertical direction on the surface of the polyimide resin layer B (22). However, it may be provided in a part of the overlapping area. The overlapping region with the polyimide resin layer A in the vertical direction on the surface of the polyimide resin layer B is a region indicated by reference numeral 211 in FIG. When the gas barrier layer is formed beyond the overlapping region 211, the outer edge portion 220 of the polyimide resin layer B located immediately below the gas barrier layer in the portion exceeding the overlapping region cannot sufficiently receive the moisture absorption treatment described later. For this reason, it becomes difficult to peel the polyimide film from the inorganic substrate. FIG. 2A is a schematic diagram (cross-sectional view) of the laminate of one embodiment according to the present invention in which the gas barrier layer 3 is formed on the surface of the polyimide resin layer B (22) of the laminate of FIG. It is. FIG. 2 (B) is a schematic sketch when the laminate of FIG. 2 (A) is viewed from above in the drawing. 2A and 2B, the same reference numerals as those in FIGS. 1A and 1B denote the same members and regions as in FIG.

By providing the gas barrier layer 3 in a part or the whole of the overlapping region 211, the area of the polyimide resin layer B exposed to the atmosphere is 10% or more of the entire area of the polyimide resin layer B. Can do. That is, even if a gas barrier layer is provided on the surface of the polyimide resin layer B, a part of the polyimide resin layer B, particularly the outer edge 220, is exposed to the atmosphere, so that peeling by moisture absorption treatment is possible. The area of the polyimide resin layer B exposed to the air is the area obtained by subtracting the surface area of the gas barrier layer from the surface area of the polyimide resin layer B. In FIG. , Equal to the area of the shaded region 220. The entire area of the polyimide resin layer B is equal to the area of the region 22 (square shape) showing the polyimide resin layer B in FIG.

As described above, since the single layer portion (outer edge portion 220) of the polyimide resin layer B (22) in contact with the inorganic substrate is firmly adhered to the inorganic substrate, the adhesion of the polyimide film 2 to the inorganic substrate is improved. It can be secured.

[Processing method of laminate]
The laminate 100 of the present invention can easily peel the polyimide film 2 from the inorganic substrate by the following treatment method (laminate treatment method 1 or 2). The peeled polyimide film 2 is useful as a flexible substrate. At this time, the polyimide-type film 2 which peeled can be made into a flexible device by forming members, such as an electronic element, in advance on the polyimide-type film 2 surface of the laminated body 100. In manufacturing a flexible device, it is preferable to form the gas barrier layer 3 on the surface of the polyimide film 2 before forming a member such as an electronic element.

(Laminate processing method 1)
First, the moisture absorption process described below is performed on the laminate 100 of the present invention. Thereafter, the polyimide film 2 is peeled off. As a specific peeling method, a method of peeling from the end portion by hand, or a method using a mechanical device such as a drive roll or a robot can be employed. Then, the polyimide-type film 2 as a flexible substrate is obtained by cutting and removing the part of the polyimide-type resin layer B (22) which was in contact with the inorganic substrate 1. The portion of the polyimide resin layer B (22) in contact with the inorganic substrate 1 is a single layer portion (outer edge portion 220) in the polyimide resin layer B (22).

In this method, for example, when using the laminated body 100 shown in FIGS. 1A and 1B, first, after performing a moisture absorption treatment, the polyimide film 2 is peeled off as shown in FIG. 3A. . Next, the polyimide film 2 as a flexible substrate as shown in FIG. 3B is obtained by cutting and removing the single layer portion (outer edge portion 220) of the polyimide resin layer B (22) as an excess portion. 3A and 3B are schematic diagrams (cross-sectional views) of a polyimide film for explaining a method of manufacturing a flexible substrate by the laminate processing method 1 using the laminate of FIG. 1A. It is. 3, the same reference numerals as those in FIG. 1 denote the same members and regions as in FIG.

In this method, for example, when the laminate 100 shown in FIGS. 2A and 2B is used, first, after performing a moisture absorption treatment, as shown in FIG. 4A, a polyimide system having a gas barrier layer 3 is used. The film 2 is peeled off. Next, the polyimide film having the gas barrier layer 3 as a flexible substrate as shown in FIG. 4B by cutting and removing the single layer portion (outer edge portion 220) of the polyimide resin layer B (22) as an excess portion. Get 2. 4A and 4B are schematic views (cross-sectional views) of a polyimide film for explaining a method for producing a flexible substrate by the laminate processing method 1 using the laminate of FIG. 2A. It is. 4, the same reference numerals as those in FIG. 2 indicate the same members and regions as in FIG.

In this method, it is preferable that the outer edge portion 220 is peeled off by moisture absorption treatment, but for example, the outer edge portion 220 can be peeled off by irradiating laser light, infrared light, ultraviolet light, flash light, or the like. Moreover, it can also peel by immersing the laminated body 100 of this invention in water.

Also in the processing method 1 of this laminated body, the polyimide film 2 obtained by previously forming members (not shown) such as electronic elements on the surface of the polyimide film 2 of the laminated body 100 is a flexible device. Useful.

(Laminate processing method 2)
First, a predetermined part of the polyimide film 2 is cut to divide the part to be peeled in the polyimide film and the part including the polyimide resin layer B (22) in contact with the inorganic substrate 1. . The predetermined part of the polyimide film to be cut is a part where the polyimide resin layer A (21) is present immediately below. Usually, as shown in FIG. 5 (A) and FIG. 6 (A), the polyimide film Cuts 200 are formed along the outer periphery of the resin layer A (21). The cutting method is not particularly limited as long as the cutting 200 reaching the inorganic substrate 1 can be formed. Examples thereof include a method using a commercially available cutter and a method using laser light irradiation. 5A and 5B are schematic diagrams (cross-sectional views) of a polyimide film for explaining a method for producing a flexible substrate by the laminate processing method 2 using the laminate of FIG. 1A. It is. 6A and 6B are schematic diagrams (cross-sectional views) of a polyimide-based film for explaining a method of manufacturing a flexible substrate by the laminate processing method 2 using the laminate of FIG. 2A. It is.

The part to be peeled is a part to be peeled thereafter, and specifically, a part 250 corresponding to the polyimide film 2 to be peeled as shown in FIG. 5 (B) and FIG. 6 (B). For example, when a member (not shown) such as an electronic element is formed on the surface of the polyimide film 2, it is a portion including a formation region of the member. The part of the polyimide resin layer B (22) in contact with the inorganic substrate 1 is also a single layer part (outer edge part 220) in the polyimide resin layer B (22) in this method.

After dividing by the notch 200 in this method, as shown in FIG. 5B and FIG. 6B, the separation planned region portion 250 is peeled to obtain a flexible substrate. Since the peeling planned region portion 250 is in contact with the inorganic substrate 1 only by the polyimide resin layer A (21), it can be easily peeled by division. As a specific peeling method, also in this method, it is possible to adopt a method of peeling from the end by hand or a method using a mechanical device such as a drive roll or a robot. Also in the processing method 2 of this laminated body, the polyimide film 2 (250) obtained by previously forming a member (not shown) such as an electronic element on the surface of the polyimide film 2 of the laminated body 100 is obtained. It is useful as a flexible device.

In this method, the polyimide resin layer B (outer edge 220) (see FIGS. 5B and 6B) remaining on the inorganic substrate is peeled off from the inorganic substrate by a moisture absorption process described later and removed. be able to. Also in this method, it is preferable that the outer edge portion 220 is peeled off by moisture absorption treatment. However, for example, the outer edge portion 220 can be peeled off by irradiating laser light, infrared light, ultraviolet light, flash light, or the like. Moreover, it can also peel by being immersed in water. The inorganic substrate from which the outer edge 220 is peeled can be reused.

(Hygroscopic treatment)
In the present invention, the moisture absorption treatment includes at least a moisture absorption treatment step for holding the laminate in a high temperature and high humidity environment.

The moisture absorption conditions are not particularly limited, but the moisture absorption treatment step is preferably performed at a relative humidity of 70% or more, more preferably 80% or more, and a moisture absorption temperature of preferably 70 ° C. or more, more preferably 80 ° C. or more. . Further, pressurized water vapor exceeding 100 ° C. can be used, but it is preferable to perform the moisture absorption treatment step at 100 ° C. or less. The moisture absorption treatment time is preferably 1 hour or longer, more preferably 3 hours or longer, and even more preferably 5 hours or longer. The upper limit of the moisture absorption treatment time is not particularly limited as long as the release of the polyimide film 2 is achieved, but the moisture absorption treatment step is usually performed for 20 hours or less, preferably 15 hours or less, more preferably 12 hours or less.

In this moisture absorption treatment, it is preferable to perform dehumidification by decompression after the moisture absorption treatment step. A polyimide film having a volume expanded by moisture absorption can be rapidly shrunk by dehumidification. By this moisture absorption and desorption operation, stress is generated in the polyimide film that expands and contracts, and the strength at the interface of the polyimide film in contact with the inorganic substrate that hardly changes in volume due to moisture absorption and desorption is significantly reduced. By this action, the polyimide film can be more easily peeled off. This moisture absorption / desorption can be further improved by repeating two or more times. In the present invention, usually, the polyimide film can be easily peeled by performing moisture absorption and desorption one to three times.

The decompression conditions are not particularly limited, but preferably the degree of decompression is 100 Torr or less, more preferably 50 Torr or less, more preferably 10 Torr or less, and the temperature is preferably 70 ° C. or more, more preferably 80 ° C. or more. . The temperature during the decompression treatment may be the same as or different from the moisture absorption treatment temperature, but is preferably the same. The decompression time is preferably 1 hour or longer, more preferably 3 hours or longer, and even more preferably 5 hours or longer. The upper limit of the reduced pressure treatment time is not particularly limited as long as the release of the polyimide film 2 is promoted, but the reduced pressure treatment step is usually performed for 20 hours or less, preferably 15 hours or less, more preferably 12 hours or less.

As a method of specifically peeling the polyimide film from the polyimide laminate treated as described above, a method of peeling from the end portion by the hand as described above, or a method of using a mechanical device such as a drive roll or a robot. Can be adopted.

The polyimide film of the present invention is preferably transparent. The light transmittance at 500 nm, which is an index of transparency, is preferably 70% or more, and more preferably 80% or more.

As described above, since the laminate of the present invention can easily obtain a polyimide-based film from a polyimide laminate by, for example, a simple process of moisture absorption treatment, it is suitable for manufacturing flexible devices and flexible wiring board devices. Can be used.

Specifically, after forming a member such as an electronic element on the surface of the polyimide film of the laminate of the present invention, the polyimide film provided with the member is peeled from the inorganic substrate. Thereby, the polyimide-type film provided with the said member can be obtained easily as a flexible device or a flexible wiring board device.

As a method for forming a member such as an electronic element, a method known in the field of electronic devices using a polyimide film as a flexible substrate can be employed. The method for forming the gas barrier layer is the same as that described above.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[Reference Example 1]
Unitika Uimide AR (polyamic acid type polyimide precursor solution obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine, the solvent being NMP, solid content The concentration was 18% by mass). This solution (polyimide solution A-1) was applied on the surface of a non-alkali glass plate having a thickness of 0.7 mm by a bar coater so that the thickness of the heat-cured film was 30 μm. The polyimide precursor film was formed by drying for a minute. Next, the temperature was raised from 100 ° C. to 350 ° C. over 2 hours under a nitrogen gas stream, and then heat treatment was performed at 350 ° C. for 2 hours to thermoset the polyimide precursor and imidize. Thus, a laminate L-1 having a glass substrate and a polyimide film layer having a thickness of 30 μm was obtained.

[Reference Example 2]
To the polyimide solution A-1, an amine-based silane coupler (KBE903 manufactured by Shin-Etsu Silicon Co., Ltd.) was added in an amount of 0.006% by mass with respect to the polyimide mass and mixed uniformly to obtain a polyimide solution A-2. A laminate L-2 having a glass substrate and a polyimide film layer having a thickness of 30 μm was obtained in the same manner as in Reference Example 1 except that this was used.

[Reference Example 3]
A silane coupler similar to that in Reference Example 2 was added to polyimide solution A-1 in an amount of 0.06% by mass based on the polyimide mass, and mixed uniformly to obtain polyimide solution B-1. A laminate L-3 having a glass substrate and a polyimide film layer having a thickness of 30 μm was obtained in the same manner as in Reference Example 1 except that this was used.

[Reference Example 4]
A silane coupler similar to that in Reference Example 2 was added to the polyimide solution A-1 at 0.1% by mass relative to the polyimide mass, and mixed uniformly to obtain a polyimide solution B-2. A laminate L-4 having a glass substrate and a polyimide film layer having a thickness of 30 μm was obtained in the same manner as in Reference Example 1 except that this was used.

[Reference Example 5]
Unitika Uimide CR (polyamic acid type polyimide precursor solution obtained from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether, and the solvent is NMP The solid concentration was 18% by mass). This solution (polyimide solution B-3) was applied to the surface of a non-alkali glass plate having a thickness of 0.7 mm by a bar coater so that the thickness of the heat-cured film was 30 μm, and 10 ° C. at 130 ° C. The polyimide precursor film was formed by drying for a minute. Next, the temperature was raised from 100 ° C. to 350 ° C. over 2 hours under a nitrogen gas stream, and then heat treatment was performed at 350 ° C. for 2 hours to thermoset the polyimide precursor and imidize. Thus, a laminate L-5 having a glass substrate and a polyimide film layer having a thickness of 30 μm was obtained.

[Reference Example 6]
To polyimide solution B-1, stearic acid was added in an amount of 0.8% by mass based on the polyimide mass, and mixed uniformly to obtain polyimide solution A-3. A laminate L-6 having a glass substrate and a polyimide film layer having a thickness of 30 μm was obtained in the same manner as in Reference Example 5 except that this was used.

<Evaluation of adhesion (before moisture absorption treatment)>
The adhesion strength between the glass substrates of the laminates L-1 to L-6 and the polyimide film layer was measured by a 180 ° peel test based on JIS K6854. In addition, when the end of the polyimide film of the laminate is cut and then pulled by hand from it, it cannot be easily peeled off from the glass plate. Was judged as “bad”. The results are shown in Table 1. In Table 1, since it is difficult to specify an accurate adhesive strength when the adhesive strength is 0.1 N / cm or less, it is described as “0.1 or less”.

As shown in Table 1, the laminates L-3, L-4, and L-5 had good adhesion. In contrast, the laminates L-1, L-2, and L-6 had poor adhesion, that is, good peelability.

<Evaluation of peelability (after moisture absorption treatment) -1>
The laminates L-3, L-4, and L-5, which had good adhesion, were treated for 10 hours under conditions of a relative humidity of 95% and a temperature of 90 ° C. to absorb the polyimide film. Thereafter, a reduced pressure treatment for 10 hours was performed at the same temperature under a reduced pressure of 5 Torr to dehumidify the polyimide that had absorbed moisture. The adhesion strength between layers of the obtained laminate was measured by a 180 ° peel test based on JIS K6854. In addition, when it can be easily peeled off from the glass plate by manually pulling from the end of the polyimide film that has been cut, the peelability at the interface is “good”, and the peelability is “bad” when it cannot be easily peeled off. Judged. The results are shown in Table 2. In Table 2, since it is difficult to specify an accurate adhesive strength when the adhesive strength is 0.1 N / cm or less, it is described as “0.1 or less”.

<Evaluation-2 of peelability (after moisture absorption treatment) -2>
Laminates L-3, L-4, and L-5, which had good adhesion, were treated for 3 hours under conditions of a relative humidity of 80% and a temperature of 50 ° C. to absorb the polyimide film. Thereafter, a reduced pressure treatment for 10 hours was performed at the same temperature under a reduced pressure of 5 Torr to dehumidify the polyimide that had absorbed moisture. The adhesion strength between layers of the obtained laminate was measured by a 180 ° peel test based on JIS K6854. In addition, when it can be easily peeled off from the glass plate by manually pulling from the end of the polyimide film that has been cut, the peelability at the interface is “good”, and the peelability is “bad” when it cannot be easily peeled off. Judged. The results are shown in Table 3.

As shown in Tables 2 and 3, the laminates L-3, L-4, and L-5, which had good adhesion before the moisture absorption treatment, were subjected to moisture absorption treatment, thereby providing a laminate having good peelability. It can be.

[Example 1]
As shown in FIGS. 1A and 1B, a polyimide solution A-1 as a solution for forming a polyimide layer A (21) is heat-cured on the surface of a non-alkali glass plate 1 having a thickness of 0.7 mm. The film was coated with a bar coater so that the thickness of the film became 3 μm, and dried at 130 ° C. for 10 minutes to form a polyimide precursor film. Here, the area of the coated surface was about 400 cm ² (20 cm × 20 cm). On the surface of this coating, polyimide solution B-1 as a solution for forming polyimide layer B (22) was applied with a bar coater so that the total thickness of the film after thermosetting was 30 μm, and dried at 130 ° C. for 10 minutes. A polyimide precursor film was formed. Next, after raising the temperature from 100 ° C. to 360 ° C. over 2 hours under a nitrogen gas stream, heat treatment is carried out at 360 ° C. for 2 hours, and the polyimide precursor is thermally cured and imidized, whereby the polyimide layer is laminated and integrated. Turned into. Here, the area of the application surface of the polyimide layer B (22) is about 576 cm ² (24 cm × 24 cm), and the outer edge portion of the polyimide layer B (22) in the outer peripheral region 210 of the polyimide layer A (21) on the glass plate surface. 220 had a width (W) of 2 cm as a single layer, and was in direct contact with the glass substrate 1. Next, as shown in FIGS. 2A and 2B, a gas barrier layer made of a silicon oxide film having a thickness of 30 nm is formed on a part of the surface of the obtained polyimide laminated film 2 (area: about 400 cm ² ) by sputtering. 3 was formed to obtain a laminate M-1. The formation region of the gas barrier layer 3 was the entire overlapping region 211 (see FIG. 1B) with the polyimide layer A (21) in the vertical direction on the surface of the polyimide layer B (22).

[Example 2]
A laminate M-2 was obtained in the same manner as in Example 1 except that the polyimide solution A-1 was changed to the polyimide solution A-2.

[Example 3]
A laminate M-3 was obtained in the same manner as in Example 1 except that the polyimide solution A-1 was changed to the polyimide solution A-3.

[Example 4]
A laminate M-4 was obtained in the same manner as in Example 1 except that the polyimide solution B-1 was changed to the polyimide solution B-2.

[Example 5]
A laminate M-5 was obtained in the same manner as in Example 1 except that the polyimide solution B-1 was changed to the polyimide solution B-3.

[Example 6]
A laminate M-6 was obtained in the same manner as in Example 1 except that the polyimide solution A-1 was changed to polyimide solution A-2 and the polyimide solution B-1 was changed to polyimide solution B-3.

[Example 7]
A laminate M-7 was obtained in the same manner as in Example 1 except that the polyimide solution A-1 was changed to polyimide solution A-3 and the polyimide solution B-1 was changed to polyimide solution B-3.

[Example 8]
A laminate M-8 was obtained in the same manner as in Example 1 except that the polyimide solution A-1 was changed to polyimide solution A-2 and the polyimide solution B-1 was changed to polyimide solution B-2.

[Example 9]
Implemented except that the area of the polyimide layer B application surface was about 484 cm ² (22 cm × 22 cm), and the outer edge 220 of the polyimide layer B was a single layer with a width (W) of 1 cm and was in direct contact with the glass substrate. In the same manner as in Example 1, laminate M-9 was obtained.

[Example 10]
Except that the area of the polyimide layer B application surface is about 441 cm ² (21 cm × 21 cm), and the outer edge 220 of the polyimide layer B is a single layer with a width (W) of 0.5 cm and is in direct contact with the glass substrate. In the same manner as in Example 1, a laminate M-10 was obtained.

[Comparative Example 1]
A polyimide solution A-1 was applied on the surface of a non-alkali glass plate having a thickness of 0.7 mm by a bar coater so that the thickness of the heat-cured film was 30 μm, and dried at 130 ° C. for 10 minutes to obtain a polyimide. A precursor film was formed. Here, the area of the coated surface was about 400 cm ² (20 cm × 20 cm). Next, under a nitrogen gas stream, the temperature is raised from 100 ° C. to 360 ° C. over 2 hours, then heat treated at 360 ° C. for 2 hours, and the polyimide precursor is thermally cured to imidize to form a polyimide layer A. did. A gas barrier layer made of a silicon oxide film having a thickness of 30 nm was formed on the entire surface (area of about 400 cm ² ) of the obtained polyimide layer A by sputtering to obtain a laminate N-1.

[Comparative Example 2]
Except that the polyimide layer B was formed using the polyimide solution B-1 instead of the polyimide solution A-1 and that the gas barrier layer was formed on the entire surface of the polyimide layer B, the same as in Comparative Example 1, A layered product N-2 was obtained.

[Comparative Example 3]
Except that the polyimide layer B was formed using the polyimide solution B-3 instead of the polyimide solution A-1 and that the gas barrier layer was formed on the entire surface of the polyimide layer B, the same as in Comparative Example 1, A layered product N-3 was obtained.

[Comparative Example 4]
A laminate N-4 was prepared in the same manner as in Example 1 except that the area of the polyimide layer B application surface was about 400 cm ² (20 cm × 20 cm), and the polyimide layer B and the polyimide layer A almost overlapped. Obtained.

<Evaluation of adhesion and peelability>
About the laminated body obtained by the above-mentioned Example and the comparative example, the adhesiveness before a moisture absorption process and the peelability after a moisture absorption process were evaluated by the method as mentioned above. In particular, the evaluation of peelability after moisture absorption treatment was in accordance with the method of “Evaluation of peelability (after moisture absorption treatment) -1”. The results are shown in Table 4.

As shown in Table 4, all of the laminates obtained in the examples had good adhesion before moisture absorption treatment and peelability after moisture absorption treatment. On the other hand, the laminate obtained in the comparative example had poor adhesion either before the moisture absorption treatment or peelability after the moisture absorption treatment.

[Example 11]
In the laminate M-1 obtained in Example 1, cuts 200 are made in the four directions around the formation region of the gas barrier layer 3 (see FIGS. 2A and 2B and FIG. 6A), and the glass substrate 1 is cut. The outer edge 220 of the polyimide layer B (22) in direct contact with the portion of the gas barrier layer 3 formation region was divided. When the end portion of the divided gas barrier layer 3 formation region was pulled by hand, the gas barrier layer 3 formation region portion could be easily separated from the glass substrate 1. Thereafter, the glass substrate (see FIG. 6B) on which the outer edge 220 of the polyimide layer B (22) remains is treated for 10 hours under the conditions of a relative humidity of 95% and a temperature of 90 ° C. Moisture was absorbed. Thereafter, a reduced pressure treatment was performed at the same temperature under a reduced pressure of 5 Torr for 10 hours to dehumidify the polyimide that had absorbed moisture. As a result, the polyimide layer B could be easily peeled off by hand. When the same operation as in Example 1 was performed using the glass substrate from which the polyimide layer B was peeled off, a laminate similar to that in Example 1 could be obtained.

[Example 12]
A laminate M-12 was obtained in the same manner as in Example 1 except that the gas barrier layer was not formed. A notch 200 is cut in four directions of the overlap region 211 (see FIG. 1B) of the laminate (see FIGS. 1A and 1B and FIG. 5A), and the polyimide is in direct contact with the glass substrate 1 The outer edge 220 of the layer B (22) and the overlapping region 211 were divided. When the end of the divided overlapping region 211 was pulled by hand, the overlapping region 211 could be easily peeled off from the glass substrate. Thereafter, the glass substrate (see FIG. 5B) on which the outer edge 220 of the polyimide layer B (22) remains is treated for 8 hours under conditions of a relative humidity of 85% and a temperature of 80 ° C. Moisture was absorbed. Thereafter, drying was performed at 100 ° C. under normal pressure for 2 hours to dehumidify the polyimide that had absorbed moisture, and the polyimide layer B could be easily peeled by hand.

[Example 13]
The glass substrate (see FIG. 5B) on which the outer edge 220 of the polyimide layer B (22) obtained in Example 12 remained was immersed in warm water at 30 ° C. for 10 hours. Then, when it dried at 100 degreeC under normal pressure for 2 hours, the polyimide layer B was able to peel easily by hand.

As described above, the laminate of the present invention can easily peel the polyimide film from the inorganic substrate by, for example, moisture absorption treatment, despite the fact that the polyimide film is firmly bonded onto the inorganic substrate. This is useful for manufacturing a flexible substrate for electronic devices made of a polyimide film. The laminate of the present invention is flexible because it has good adhesion before moisture absorption treatment and peelability after moisture absorption treatment even when a gas barrier layer is formed on the surface of the polyimide film constituting the laminate. This is useful when manufacturing a flexible device or flexible wiring board in which a member such as an electronic element is formed on a polyimide film as a substrate.

1: Inorganic substrate 2: Polyimide film 21: Polyimide resin layer A (for example, polyimide layer A)
22: Polyimide resin layer B (for example, polyimide layer B)
3: Gas barrier layer 210: Peripheral region 211: Overlapping region with polyimide resin layer A (21) in the vertical direction on the surface of polyimide resin layer B (22) 220: Outer edge

Claims

A laminate having an inorganic substrate and a polyimide-based film formed on the inorganic substrate, the laminate having the following characteristics:
(1) The polyimide film is a laminated film including a polyimide resin layer A and a polyimide resin layer B, the entire surface of the polyimide resin layer A is in contact with the inorganic substrate, and is on the surface of the polyimide resin layer A. Part of the formed polyimide resin layer B is in contact with the inorganic substrate;
(2) The adhesive strength between the polyimide resin layer A and the inorganic substrate is 2 N / cm or less;
(3) The adhesive strength between the polyimide resin layer B and the inorganic substrate is more than 2 N / cm;
(4) The polyimide resin layer B in contact with the inorganic substrate can be peeled from the inorganic substrate by moisture absorption treatment.
The laminate according to claim 1, wherein the inorganic substrate is a glass substrate.
The laminate according to claim 1 or 2, wherein a gas barrier layer is formed on the surface of the polyimide resin layer B.
A method for treating a laminate, comprising subjecting the laminate according to any one of claims 1 to 3 to moisture absorption treatment to peel the polyimide film from the inorganic substrate.
5. The laminate according to claim 4, wherein the moisture absorption treatment is a treatment of dehumidification by reducing pressure after holding the laminate in an environment of a temperature of 100 ° C. or less and a relative humidity of 70% or more. Processing method.
An inorganic substrate is formed by forming one or more members selected from electronic elements and wirings on the surface of the polyimide film of the laminate according to any one of claims 1 to 3, and then subjecting the laminate to moisture absorption treatment. The method for producing a flexible device is characterized in that a flexible device is obtained by peeling off the polyimide film provided with the member and then cutting and removing the portion of the polyimide resin layer B that has been in contact with the inorganic substrate.
One or more members selected from electronic elements and wirings are formed on the surface of the polyimide-based film of the laminate according to any one of claims 1 to 3, and the polyimide-based film provided with the members has a predetermined portion. After cutting and dividing the member forming region portion in the polyimide film and the polyimide resin layer B portion in contact with the inorganic substrate, the member forming region portion in the polyimide film is peeled off. A method for producing a flexible device, comprising obtaining a flexible device and removing the polyimide-based resin layer B remaining on the inorganic substrate from the inorganic substrate by moisture absorption treatment.
8. The flexible according to claim 6, wherein the moisture absorption treatment is a treatment of dehumidification by reducing pressure after holding the laminate in an environment of a temperature of 100 ° C. or less and a relative humidity of 70% or more. Device manufacturing method.