TWI662868B - Manufacturing method of display device, resin solution, and exfoliation device - Google Patents

Abstract

Provided is a method for easily separating a flexible substrate from a support after a predetermined functional layer is formed on the flexible substrate, and a display device can be easily obtained. A method for manufacturing a display device includes: a step of applying a resin solution on a support to form a flexible substrate on the support; a step of forming a functional layer on the flexible substrate; and self-forming a functional layer In the step of removing the support from the flexible substrate, the peeling strength between the flexible substrate and the support in the functional layer formation region where the functional layer is formed is 200 N / m or less and 0.1 N / m or more. A peeling prevention portion is formed at the position. After the peeling prevention portion is separated from the flexible substrate in the functional layer formation region, the support is removed from the flexible substrate.

Description

Manufacturing method of display device, resin solution and peeling device

The invention relates to a method for manufacturing a display device, and in particular, to a display device such as a liquid crystal display device, an organic electroluminescence (EL) display, organic EL lighting, electronic paper, a touch screen, and a color filter. Or a method of a display device in which a member for a display device is formed on a flexible substrate.

A display device such as a liquid crystal display device or an organic EL display device is used for various display applications such as a large display such as a television, or a small display such as a mobile phone, a personal computer, and a smartphone. A typical device of a display device is an organic EL display device. For example, the organic EL display device is formed by forming a thin film transistor (hereinafter referred to as a thin film transistor) on a glass substrate as a supporting substrate, and sequentially forming electrodes and a light emitting layer. And electrodes are finally manufactured by hermetically sealing with another glass substrate or a multilayer film.

Here, by replacing a glass substrate with a resin substrate from a conventional glass substrate, it is possible to realize a thin, lightweight, flexible, and further expand the use of the display device. However, generally speaking, compared with glass, the resin has poor dimensional stability, transparency, heat resistance, moisture resistance, gas barrier properties, etc. Conduct various seminars.

For example, Patent Document 1 relates to an invention of polyfluorene and a precursor thereof which are effectively used as a plastic substrate for a flexible display, and it is reported that an alicyclic type such as cyclohexylphenyltetracarboxylic acid is used. A polyfluorene imide formed by a tetracarboxylic acid having a structure and reacting with various diamines is excellent in transparency. In addition, attempts have been made to reduce weight by using a flexible resin for a supporting substrate. For example, in the following Non-Patent Document 1 and Non-Patent Document 2, a polyimide having high transparency is proposed. It is applied to an organic EL display device that supports a substrate.

As described above, it is known that resin films such as polyimide are useful for flexible substrates for flexible displays. However, the manufacturing steps of display devices have been performed using glass, and most of the production equipment is based on the use of glass. While designing. Therefore, it is desirable to effectively use existing production equipment while producing a display device.

As one of the specific examples of this study, it is known to use glass as a support, and a predetermined display device manufacturing process is completed in a state where a resin substrate is laminated on the glass, and thereafter the glass is removed to produce flexible materials. A method of a display device including a display portion on a substrate (see Patent Documents 2 to 8 and Non-Patent Documents 3 to 4). Further, in these cases, in a predetermined step in the manufacturing process of the display device, it is necessary that the glass and the resin substrate adhere well without peeling, and that the display portion (display portion) formed on the resin substrate is not damaged. The resin substrate is separated from the glass.

That is, in Non-Patent Document 3, after a predetermined display portion is formed on a resin substrate coated on glass and adhered, a plastic-based electron is released using a laser. (Electronics on Plastic by Laser Release, EPLaR) process, which irradiates a laser from the glass side, and separates a resin substrate including a display portion from the glass. In this method, a laser is irradiated after a display portion is formed on a resin substrate. Therefore, a laser that has passed through the resin substrate may cause damage to functional layers such as a TFT and a color filter. In particular, if a highly transparent resin is applied to a resin substrate, a laser can easily penetrate the resin layer, and the possibility of damaging the functional layer is further increased. If the intensity of the laser is reduced in order to avoid damage to the functional layer, there is a problem that productivity decreases.

On the other hand, the method described in Non-Patent Document 4 is a method in which the shortcomings of the EPLaR method are improved, and is a method in which a release layer is coated and formed on a glass substrate, and then polyurea is applied to the release layer. Amine resin, and after the manufacturing step of the organic EL display device is completed, the polyimide film layer is peeled from the release layer. That is, in this method, after the release layer 2 is formed on the glass 1, a polyimide layer 3 that is one week longer than the release layer 2 is formed, and thereafter, a predetermined TFT and an organic EL step are processed to form a TFT / After the organic EL panel portion (display portion) 4 is cut along the cutting line 5 on the inner side of the release layer 2 to the release layer 2, the polyimide layer 3 and the TFT / organic EL panel portion (display) are peeled from the release layer 2.部) 4. However, Non-Patent Document 4 does not specifically describe what kind of substance is used for the release layer. For this reason, it is not clear what level of force is actually required for the separation of the self-peeling layer, or the state of the surface properties of the separated polyfluoreneimine layer 3. In addition, since the area of the release layer needs to be smaller than the area of the polyimide layer, the area that can be formed by the organic EL display device is limited, which is problematic in terms of productivity. If the area of the release layer is increased in order to prevent a decrease in productivity, the area of the polyimide layer adhered to the glass at the outer peripheral portion of the release layer It is reduced, and there is a problem that peeling tends to occur due to the stress in the step.

The method described in Patent Document 2 is a method of forming a peeling layer containing Parylene or a cyclic olefin copolymer on glass, and then making the peeling layer one week longer than the peeling layer in the same manner as in the method described in Non-Patent Document 4. In this way, a polyfluorene imide layer is formed, and an electronic device is fabricated thereon, and then the polyfluorene imide layer is peeled off. For the formation of TFTs required for display applications, an annealing step of about 400 ° C is generally required. However, in this method, the heat resistance of the release layer is lower than that of polyimide. Or, the maximum temperature at the time of making an electronic device is limited by the heat resistance of the release layer. In addition, weak adhesion between the glass and the release layer, and between the release layer and the polyimide layer may cause peeling due to being unable to withstand the stress in the step. In addition, the thermal expansion coefficient of the release layer is larger than that of polyimide, and the difference in thermal expansion coefficient caused by the difference in the resin type may be a factor of warpage.

The method described in Patent Document 3 is a method for manufacturing a photovoltaic device in which a photoelectric conversion element is formed on a resin layer after a resin layer is formed on a support, and the support and the resin layer are provided in a dense manner around a portion of the photovoltaic device. Focus on the high part. Polyimide is exemplified as the resin layer, but a method for removing polyimide from a support is not disclosed. Unlike photovoltaic devices, organic EL display devices require very high gas barrier properties. Therefore, a dense barrier layer must be formed on the resin layer. However, if the peel strength of the support and the resin layer is high, there may be a problem during peeling. A crack is formed in the barrier layer, and gas barrier properties are reduced. In addition, the display device is required to be further thinner and lighter, and the demand for thinner resin layers is far stronger than that of photovoltaic devices. In the tree When the thickness of the lipid layer is 30 μm or less, the peel strength of the support and the resin layer cannot be properly controlled. When peeling, the resin layer will stretch, and the gas barrier layer, circuit, TFT, color filter, and indium tin oxide (Indium Tin) The functional layers of display devices such as Oxide (ITO) are damaged. In addition, in order to reuse the support, it is also necessary to peel off the part surrounding the photovoltaic device part from the support. However, the method of Patent Document 3 must have a stronger adhesion part than the photovoltaic device part, so there is peeling of the part. The possibility of becoming difficult.

Patent Documents 4 and 5 disclose a method of manufacturing a device that controls the peel strength of a support and a polyfluorene film substrate by changing the ratio of a diamine and an acid anhydride having a specific chemical structure. A method that satisfies the actual peel prevention of the support and the polyimide film substrate in a predetermined step and the excellent peelability after the predetermined step is described. In addition, the obtained polyfluorene imine is colored yellow-brown and has poor transparency, so the application range of the display device is limited. Further, Patent Document 5 discloses that if the peel strength is less than 160 N / m, it cannot withstand a wet cleaning step or the like in a manufacturing process, and it is difficult to use it as a practical device.

The method of Patent Document 6 is a method for producing a laminate of a support and a resin layer as an inorganic material, and after the coupling agent treatment on the surface of the support is performed, the coupling agent is patterned by ultraviolet (UV) irradiation or the like. A method of producing a laminated body having a good adhesion portion and an easily peelable portion having different peel strengths by chemical treatment. In this method, it is necessary to perform a coupling agent treatment and patterning, and therefore there are problems that the cost increases and the yield decreases due to an increase in the number of steps. Furthermore, it is difficult to control the peeling strength reproducibility of each portion to a predetermined value. In addition, in practical terms, In most cases, the support is reused and reused. For reuse, it is preferable that the good adhesion part can be easily peeled off, but this method does not consider the peelability of the good adhesion part. According to the embodiment, the good adhesion part In many cases, the peel strength is 500 N / m or more, and it is difficult to peel.

The method of Patent Document 7 discloses a method of manufacturing a display device in which a peripheral portion is formed at a temperature higher than the film formation temperature after the film material layer provided on the support is heated to form the film layer and before the display layer is formed. After heating, a peeling prevention portion having a high adhesive force is provided, and after the display layer is formed, the peeling prevention portion is heated to peel the film material from the supporting substrate. In this method, part of the heating of the film material needs to be performed twice before and after the display layer is formed, and there is a problem that the cost increases due to an increase in the number of steps, and further, special equipment for peeling such as laser is required. In addition, the means for controlling the peeling strength of the display layer forming portion is not described.

The method of patent document 8 is a method of forming a flexible substrate on a release layer after forming a release layer on a support, and peeling between the release layer and the flexible substrate. As the release layer, molybdenum, nickel, and silicon nitride are disclosed. In this method, steps such as sputtering and photolitho-etching are required to form a patterned peeling layer, and there is a problem that the cost increases due to an increase in the number of steps. In addition, in the manufacturing process, foreign matter may be mixed in due to the peeling off of the release layer, and the process may be contaminated. When the peeling layer is peeled off due to brush cleaning or the like before the step of putting the support into use and before reuse, the problem of poor peeling of the flexible substrate also occurs.

In these methods, glass is used as a supporting substrate, and a display portion is formed on a flexible substrate fixed to the glass, thereby ensuring the handleability or size of the flexible substrate. In addition, the current production line for manufacturing display devices such as liquid crystal display devices and organic EL display devices has the advantage that glass can be used directly.

However, since the support and the flexible substrate are laminated without peeling, they can be separated very easily after forming a predetermined display portion, the damage to the flexible substrate or the display portion is small, and simple means can be used. From the viewpoint of removing the flexible substrate remaining on the supporting substrate removed from the flexible substrate, the method is not sufficient, and further improvement is required.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-231327

[Patent Document 2] Japanese Patent Laid-Open No. 2010-67957

[Patent Document 3] Japanese Patent Laid-Open No. 4-212475

[Patent Document 4] Japanese Patent Laid-Open No. 2012-140560

[Patent Document 5] Japanese Patent Laid-Open No. 2012-140561

[Patent Document 6] Japanese Patent Laid-Open No. 2013-10340

[Patent Document 7] Japanese Patent Laid-Open No. 2013-73001

[Patent Document 8] Japanese Patent Laid-Open No. 2013-168445

[Non-patent literature]

[Non-Patent Document 1] S. An et al., "2.8-inch WQVGA Flexible Active Matrix Organic Light-Emitting Diode Using High-Performance, Low-Temperature Polycrystalline Silicon Thin Film Transistors on Plastic Substrates", Society for Information Display Information Display (SID) 2010 Abstract (S. An et. Al., "2.8-inch WQVGA Flexible AMOLED Using High Performance Low Temperature Polysilicon TFT on Plastic Substrates ", SID2010 DIGEST), p706 (2010)

[Non-Patent Document 2] Dashi et al. "Transparent PI for flexible display" (Oishi et.al., "Transparent PI for flexible display"), IDW'11 FLX2 / FMC4-1

[Non-Patent Document 3] East India Haskal et al. "Flexible organic light-emitting diode displays manufactured using EPLaR process", EI Haskal et. Al. "Flexible OLED Displays Made with the EPLaR Process ", Proc. Eurodisplay), 07, pp. 36-39 (2007)

[Non-Patent Document 4] Li Zhengzhong et al. "A Novel Method for Manufacturing Flexible Active Matrix Displays", Abstract of the International Institute of Information Display 10 (Cheng-Chung Lee et. Al. "A Novel Approach to Make Flexible Active Matrix Displays ", SID10 Digest), pp.810-813 (2010)

Therefore, an object of the present invention is to provide a method for easily separating a flexible substrate from a support after a predetermined functional layer is formed on a flexible substrate integrated with a support in advance, so that a display device can be easily obtained. .

The present inventors conducted diligent research in order to solve the above problems, and as a result, found that the peeling strength between the flexible substrate and the support in the functional layer formation region in which the functional layer is formed is set to 200 N / m or less, 0.1 N / m or more, and at a position surrounding the functional layer forming area, a peeling prevention portion for preventing the flexible substrate from peeling from the support is formed. After separating the flexible substrate and the peeling preventing portion from the functional layer forming area, The support is separated from the flexible substrate provided with the functional layer, thereby guaranteeing The present invention has completed the present invention by processing the flexible substrate with dimensional stability and manufacturing a functional layer with high accuracy. Furthermore, the flexible substrate can be easily separated from the support to obtain a display device.

That is, the present invention is a method for manufacturing a display device, which is a method for manufacturing a display device, and has a flexible substrate forming step of applying a resin solution to a support to form a flexible substrate on the support; a function A layer forming step for forming a functional layer on the flexible substrate; and a support removing step for removing the support from the flexible substrate having the functional layer formed thereon. The method for manufacturing a display device is characterized in that: The peeling strength of the flexible substrate and the support in the functional layer formation region of the functional layer is 200 N / m or less and 0.1 N / m or more, and a position preventing the flexible substrate from forming is formed around the functional layer formation region. As a result, the peeling prevention portion of the support is not subjected to a partial chemical surface treatment on the functional layer formation region or the portion of the support corresponding to the peeling prevention portion, or the portion of the support corresponding to the peeling prevention portion is not performed. Local heating is performed, and in the support removing step, after the flexible substrate in the functional layer formation region is separated from the peeling prevention portion, it has its own function. A flexible substrate support layer is removed.

In the method for manufacturing a display device of the present invention, it is preferable that, in the support removing step, the support is removed from a flexible substrate having a functional layer after removing the peeling prevention portion from the support.

In the method for manufacturing a display device according to the present invention, the peeling strength of the flexible substrate and the support in the peeling prevention portion is preferably 500 N / m or less.

In the method for manufacturing a display device of the present invention, it is preferable that the flexible substrate is formed of two or more resin layers, and any one or more of these resin layers protrude toward the outer peripheral side of the functional layer forming region. Adhesion to the support forms a peeling prevention portion, and the thickness of the peeling prevention portion is thinner than the thickness of the flexible substrate in the functional layer formation region.

Further, in the method for manufacturing a display device of the present invention, it is preferable that the peeling prevention portion is a portion where a surface of a support body that is in contact with a flexible substrate on the outer peripheral side of the functional layer formation region is roughened. .

In the method for manufacturing a display device according to the present invention, it is preferable that the peeling prevention portion is formed by a part of a constituent material of a functional layer, and a part of the constituent material of the functional layer forming the peeling prevention portion is formed in a functional layer region. The outer peripheral side of the body protrudes and adheres to the support.

In the method for manufacturing a display device according to the present invention, it is preferable that a part of a constituent material of the functional layer forming the peeling prevention portion is an inorganic layer formed of an inorganic material.

In the method for manufacturing a display device according to the present invention, it is preferable that the peeling prevention portion is formed of a peeling prevention layer, and the peeling prevention layer is interposed between the flexible substrate and the flexible substrate on the outer peripheral side of the functional layer formation region. Between supports.

In addition, the method for manufacturing a display device according to the present invention is preferably characterized in that, before the functional layer forming step, only the functional layer forming region of the flexible substrate formed in the flexible substrate forming step is corresponding. The UV laser beam is irradiated at the position, and thus the flexible substrate and the support are peeled off compared to the functional layer formation region. The strength is to increase the peeling strength of the flexible substrate and the support around the position where the functional layer is formed, and to form a peeling prevention portion.

In the method for manufacturing a display device of the present invention, the thickness of the flexible substrate is preferably 0.1 μm or more and 30 μm or less.

In the method for manufacturing a display device of the present invention, it is preferable that the flexible substrate contains polyimide.

In the method for manufacturing a display device of the present invention, it is preferable that, in the flexible substrate forming step, a polyimide or a polyimide precursor resin solution is applied to a support, Heat treatment is performed in an oxidizing environment to obtain a flexible substrate.

In the method for manufacturing a display device of the present invention, it is preferable that, in the flexible substrate forming step, a polyimide or a polyimide precursor resin solution is applied to a support, Heat treatment is performed at 280 ° C or higher to obtain a flexible substrate.

In the method for manufacturing a display device of the present invention, it is preferable that, in the flexible substrate forming step, a polyimide or a polyimide precursor resin solution is applied to a support, A flexible substrate is obtained by continuous heat treatment.

Furthermore, the method for manufacturing a display device of the present invention is characterized in that the display device is preferably a touch screen.

In addition, the present invention is characterized by a resin solution of polyimide or a polyimide precursor for forming a flexible substrate, which is used for manufacturing the display device. Manufacturing method, and forming an adhesive surface at least in contact with the support.

Moreover, this invention is a resin or resin solution for peeling prevention layers which comprises the peeling prevention layer used for the manufacturing method of the said display device.

In addition, the present invention is a peeling device for manufacturing a display device, which is used in the manufacturing method of the display device and has a substrate having a fixed functional layer forming region, and the peeling device is a flexible substrate from the substrate to the functional layer forming region. The support is removed by applying a stress required to remove the support from the flexible substrate.

In the manufacturing method of the display device of the present invention, in the manufacturing steps, a part of the support is not subjected to chemical surface treatment or heating, so that the support and the flexible substrate are laminated without peeling, and it is extremely simple to form a predetermined functional layer Since the display device is separated from the ground without damaging the flexible substrate or the functional layer, it is excellent in mass productivity. In addition, after the display device is removed, the frame-shaped flexible substrate (that is, the portion corresponding to the peeling prevention portion) remaining on the support can be removed by a simple means, and therefore, the reuse of the support is facilitated. As a result, in the manufacture of a display device, replacement from a glass substrate to a flexible substrate can be further promoted.

101‧‧‧stainless steel foil

102‧‧‧polyimidea

201, 301, 401, 501, 601, 701, 801‧‧‧ glass

203‧‧‧polyimide b

304, 604, 704, 804‧‧‧ polyimide c

305, 405, 505‧‧‧Polyimided

406‧‧‧Polyimide e

507‧‧‧Polyimide f

608, 808‧‧‧‧ Silicon nitride film

709‧‧‧glass paste

900‧‧‧ stripping device

901‧‧‧ support

902‧‧‧ flexible substrate

903‧‧‧Functional Layer

904‧‧‧ substrate

905‧‧‧Separation Prevention Division

906‧‧‧ Functional layer formation area

FIG. 1 is a schematic explanatory diagram showing a method of manufacturing a display device according to the first embodiment.

FIG. 2 is a schematic explanatory diagram illustrating a method of manufacturing a display device according to a second embodiment.

FIG. 3 is a schematic explanatory diagram illustrating a method of manufacturing a display device according to a third embodiment.

FIG. 4 is a schematic explanatory diagram illustrating a method of manufacturing a display device according to a fourth embodiment.

FIG. 5 is a schematic explanatory diagram illustrating a method of manufacturing a display device according to a fifth embodiment.

FIG. 6 is a schematic explanatory diagram illustrating a method of manufacturing a display device according to a sixth embodiment.

FIG. 7 is a schematic explanatory diagram illustrating a method of manufacturing a display device according to a seventh embodiment.

FIG. 8 is a schematic explanatory diagram showing a method of manufacturing a display device of Comparative Example 4. FIG.

FIG. 9 is a schematic explanatory view showing a peeling device of the present invention.

Hereinafter, one embodiment of a method for manufacturing a display device of the present invention will be described in detail.

First, prepare the support. This support plays the role of a base when forming a display part as a functional layer in the manufacturing process of an organic EL display device, for example. In addition, in the manufacturing steps of the touch screen, it plays the role of a base when forming an electrode layer, such as the formation of a transparent conductive film or circuit processing. The support is not particularly limited as long as it has chemical strength or mechanical strength as follows: That is, it can withstand the thermal history, environment, and the like in the manufacturing process of the functional layer forming the display portion of various display devices, and can be exemplified Glass, ceramic, silicon, metal foil, or a rigid resin plate, glass and resin composite material, preferably a glass plate or a silicon wafer can be used. The support may be subjected to a known cleaning method or surface treatment, but it is not necessary to perform local cleaning or chemical surface treatment patterning on the support. When glass is used as a support, for example, it can be used by ordinary users in the manufacture of organic EL display devices or touch screens. In the display device manufactured by the present invention, the supporting substrate in the display device is a flexible substrate including a resin layer. That is, although the supporting body functions as a base when a functional layer such as a display portion is formed on a flexible substrate, and in the manufacture of the functional layer, In the process, the handleability or dimensional stability of the flexible substrate is guaranteed, but it will eventually be removed instead of constituting a component of the display device.

Furthermore, the method for manufacturing a display device of the present invention includes the following steps: a flexible substrate forming step, a resin solution is applied on the support to form a flexible substrate on the support; a functional layer forming step Forming a functional layer such as a display portion on the flexible substrate to form a functional layer; and a support removing step to separate the flexible substrate on which the functional layer is formed from the support.

First, a flexible substrate forming step will be described.

In the flexible substrate forming step, it is preferable to perform a heat treatment after coating the resin solution on the support. The heat treatment has the effects of removing the solvent from the resin solution applied on the support, curing the resin, forming a flexible substrate having excellent heat resistance, solvent resistance, and the like, and providing self-supporting to the flexible substrate. Body peelability. The condition is preferably a heating time (hereinafter referred to as a "high temperature holding time") in the high temperature heating temperature region (hereinafter referred to as "high temperature holding time") which is lower than the maximum heating temperature (highest reaching temperature) during the heat treatment by a temperature of 20 ° C. ) Is set within 15 minutes. If the high-temperature holding time exceeds 15 minutes, the flexible substrate tends to become brittle. When transparency is required for a flexible substrate, if the high-temperature holding time exceeds 15 minutes, the transparency of the flexible substrate tends to decrease due to coloring and the like. In order to maintain the mechanical strength and transparency of the flexible substrate, the high-temperature holding time should be short, but if it is too short, the effect of the heat treatment may not be sufficiently obtained. The optimal high-temperature holding time varies depending on the heating method, the heat capacity of the support, and the thickness of the flexible substrate. For example, when the flexible substrate is polyimide, it is more preferably set to 0.5. More than 5 minutes.

In addition, in the flexible substrate forming step of the present invention, no chemical surface treatment or heating is performed locally on the functional layer formation region or a portion of the support corresponding to the peeling prevention portion. Here, the chemical surface treatment includes, for example, coating, sputtering, vapor deposition, or lamination of a low-molecular compound such as a silane coupling agent, an inorganic substance such as molybdenum, nickel, and silicon nitride, or a polymer compound, and physical properties such as roughening. Different surface treatments.

In the flexible substrate forming step, the appropriate maximum heating temperature in the heat treatment varies depending on the type of resin or solvent, the thickness of the resin, the material or thickness of the support, and the heating time. The flexible substrate is polyimide. In this case, it is preferably 230 ° C or higher. If the maximum heating temperature is lower than 230 ° C, a solvent remains in the obtained flexible substrate, and there is a possibility that it may become a problem in the manufacturing steps. Furthermore, in order to facilitate removal of the support in the subsequent support removal step, the highest reaching temperature is preferably a temperature higher than 280 ° C, and more preferably a temperature higher than 330 ° C. The heat treatment may be a batch heat treatment in which the laminated body is installed in a heat treatment apparatus without being moved, or may be continuously transferred to the heat treatment apparatus set to a predetermined temperature. Continuous heat treatment is performed. Compared with the batch heat treatment, the continuous heat treatment is advantageous in terms of improvement in productivity, uniformization of the heat treatment temperature, and shortening of the maximum heating temperature. In addition, when the flexible substrate is polyimide, the upper limit of the heat treatment temperature varies depending on the chemical structure of the polyimide. However, if the heat treatment temperature is too high, the mechanical or optical characteristics of the polyimide will decrease. Therefore, it is substantially 550 ° C.

In addition, when the flexible substrate is polyimide, it is preferably in an oxidizing ring. The heat treatment is performed under ambient conditions. Heat treatment in an oxidizing environment has the effect of easily peeling the flexible substrate from the support. Here, the oxidizing environment refers to a gas containing more than 5% of oxygen atoms, and specific examples include air, oxygen, oxygen-enriched air, and a mixed gas of oxygen and an inert gas. Heat treatment in an air environment is relatively low because of low cost. good.

In addition, the chemical structure of the resin constituting the flexible substrate may be such that the peel strength of the flexible substrate and the support in the formation region of the functional layer (hereinafter referred to as "peeling of the functional layer formation region") The "strength") is not less than 200 N / m and not less than 0.1 N / m, but is not limited. From the viewpoints of heat resistance and dimensional stability, polyfluorene imine is preferred.

When the flexible substrate is polyimide, the structure of the polyimide includes a structural unit represented by the following general formula (1).

Here, Ar ₁ represents a tetravalent organic group, and Ar ₂ represents a divalent organic group.

Ar _{1 is} preferably any one of the tetravalent organic groups represented by the following formula (4).

In addition, Ar _{2 is} preferably represented by the following general formula (2) or general formula (3).

Here, R ₁ to R ₈ are each independently a hydrogen atom, a fluorine atom, an alkyl or alkoxy group having 1 to 5 carbon atoms, or a fluorine-substituted hydrocarbon group.

In order to improve the peelability of the flexible substrate from the support, it is more preferable to use a so-called fluorinated polyfluorene imine containing a fluorine atom or a fluorine-substituted hydrocarbon group in Ar ₁ or Ar ₂ . For example, at least one of R ₁ to R ₄ is preferable for the general formula (2), and at least one of R ₁ to R ₈ is preferably a fluorine atom or a fluorine substitution for the general formula (3). Alkyl.

When the flexible substrate is polyimide, the resin solution A solution of polyimide or a precursor of polyimide. When the solution is a polyimide precursor, it can be produced by polymerizing a diamine and an acid anhydride as raw materials in the presence of a solvent to prepare a solution of the polyimide precursor, and then coating the solution on a support. The body is heat treated to undergo imidization. Moreover, when it is a solution of polyimide, it can manufacture by apply | coating the solution of polyimide to a support, heat-processing, and drying.

The molecular weight of the polyfluorene imide film can be controlled mainly by changing the molar ratio of the diamine and the acid anhydride as a raw material, and the molar ratio is usually 1: 1. It can be adjusted to 0.985 ~ 1.015 as needed.

Regarding the solution of the polyfluorene imide precursor, first, after dissolving the diamine in an organic solvent, an acid dianhydride is added to the solution, so that a polyfluorene acid which is a polyfluorine imide precursor can be produced. Examples of the organic solvent include dimethylacetamide, dimethylformamide, n-methylpyrrolidone, 2-butanone, diglyme, and xylene. These may be used alone or in combination. Two or more kinds can be used in combination.

When applying the obtained solution of the polyimide precursor to a support, it is preferable to adjust the concentration or molecular weight of the polyimide precursor to set the viscosity of the solution in the range of 500 cps to 70,000 cps. The coating method is not particularly limited, and a known method such as a spin coater, a spray coater, a bar coater, or a method of extrusion from a slit-shaped nozzle can be applied as long as a predetermined thickness accuracy is obtained. Furthermore, the surface of the base body or the base material to be the coating surface of the resin solution may be appropriately subjected to surface treatment and then coated.

In addition, the thickness of the flexible substrate is not limited, and the lower limit of the thickness is relatively small. It is preferably 0.1 μm, and more preferably 0.3 μm. If the thickness is less than 0.3 μm, pinholes may be generated in the flexible substrate due to foreign substances mixed in the manufacturing process. If the thickness is less than 0.1 μm, needles may be generated due to abnormal protrusions on the surface of the support. Possibility. The upper limit of the thickness is preferably 30 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. In order to make the thickness of the display device sufficiently thin, the thickness of the flexible substrate may be 30 μm or less, and in order to obtain good flexibility, the thickness of the flexible substrate may be 10 μm or less. Furthermore, by setting it to 5 μm or less, it is possible to obtain a high transmittance in a wide wavelength range required for display device applications.

Here, the peeling strength between the flexible substrate and the support in the functional layer formation region needs to be 200 N / m or less and 0.1 N / m or more.

When the peel strength of the functional layer formation region is higher than 200 N / m, the barrier layer formed on the flexible substrate or further the functional layer such as TFT, color filter, circuit, and ITO is easily damaged when peeled from the support. When the barrier layer is damaged, even if there is no problem in the characteristics of the initial display device, the characteristics are deteriorated after long-term use. When the support and the flexible substrate are not adhered, a flexible substrate from the support may be generated due to a difference in thermal expansion between the support and the flexible substrate due to a stress or temperature change in the functional layer forming step. Therefore, the functional layer formation area needs to be adhered to the support with a peeling strength of 0.1 N / m or more. Therefore, in the present invention, it is preferable that the peeling strength of the functional layer forming region is low, and the peeling strength of the functional layer forming region is 200 N / m or less, 0.1 N / m or more, and preferably 50 N / m or less, and 0.1 N / m or more It is more preferably 10 N / m or less and 0.1 N / m or more.

Moreover, the transmittance of the flexible substrate in a wavelength range of 440 nm to 780 nm is preferably 80% or more.

When the display device is an organic EL display device, the wavelength of light emitted from the light-emitting layer of the organic EL is mainly 440 nm to 780 nm. Therefore, the average transmittance of the substrate for the organic EL display device in the wavelength range is preferably at least More than 80%. The average transmittance is more preferably 85% or more at 440 nm to 780 nm.

The flexible substrate may be formed of a single resin layer, or may be formed of a plurality of resin layers. If multiple layers are included, for example, a layer that is in contact with the support is set as the first resin layer, and a surface of the first resin layer that is in contact with the support is in contact with the opposite surface. If the resin layer is a second resin layer, the first resin layer and the second resin layer may have the same chemical structure or different chemical structures. When the flexible substrate includes a plurality of resin layers, it is preferable that a layer (at least the first resin layer in the previous example) that is in contact with the support has the polyfluorene imine structure. Furthermore, it is preferable that a plurality of resin layers preferably have the polyfluorene imine structure. When the flexible substrate includes a plurality of resin layers, an inorganic layer such as SiO ₂ may be provided between the resin layers.

When forming a flexible substrate with a plurality of resin layers, at least a part of any one of the resin layers may be formed so as to protrude from a peripheral portion of another resin layer. Accordingly, a portion having a thickness smaller than that of the functional layer forming region is provided in the peripheral portion of the flexible substrate, and stress concentrated on the end surface of the flexible substrate can be dispersed in the manufacturing process, so that the support and the flexible substrate can be prevented from Peeling during the manufacturing steps.

That is, for example, a resin solution is applied to a support and heat-treated. The obtained first resin layer is coated with a resin solution and heat-treated, so that the second resin layer having a film thickness larger than the first resin layer and one week shorter than the first resin layer is laminated, and the first resin layer protruding from the second resin layer is laminated. A protruding portion of a resin layer forms a peeling prevention portion. In addition, if the peeling prevention portion is cut and separated after the functional layer is formed on the second resin layer, the remaining first resin layer and the second resin layer constitute a flexible substrate. Here, the protruding distance (width) of the first resin layer is preferably equal to or greater than the total thickness of the first resin layer and the second resin layer, and more preferably 10 times the total thickness of the first resin layer and the second resin layer. the above. As described above, the flexible substrate having the functional layer forming region where the functional layer is formed has a peel strength between the flexible substrate and the support of 200 N / m or less and 0.1 N / m or more, and the functional layer forming region is surrounded (surrounded). A peel-off preventing portion which is more difficult to peel off than the flexible substrate in the functional layer formation region is formed at the position, and a laminated structure suitable for manufacturing a display device including the functional layer on the flexible substrate can be manufactured. In addition, the film thickness of the second resin layer may be the same as the film thickness of the first resin layer, or may be smaller than the film thickness of the first resin layer. The total layer thickness of the first resin layer and the second resin layer laminated on the first resin layer is preferably larger than the layer thickness of the first resin layer on the peeling prevention portion. The average value of the film thickness is more preferably more than 1 μm. Here, the average value of the film thickness is an average value of the film thickness at any of ten places measured with a dial gauge or a micrometer.

Next, the steps of forming a functional layer will be described.

The functional layer differs depending on the display device to be manufactured. For example, in the case of an organic EL device, a barrier layer, a TFT, an ITO, an organic EL light-emitting layer, a color filter layer, and the like can be cited. In the case of a touch screen, examples include transparent conductive films, metals Grid and other electrode layers. As a method of forming these functional layers, a known method can be applied.

In addition, a peeling prevention portion that prevents the flexible substrate from peeling off the support is formed at a position surrounding the functional layer. In the next support removing step, the flexible substrate in the functional layer formation region is cut from the peeling prevention portion. After that, the support is removed from the flexible substrate including the functional layer.

Here, if the peeling prevention portion is more difficult to peel off than the other portion (that is, the flexible substrate in the functional layer formation region) in the support removing step, the shape or property thereof is not particularly specified. For example, the peel strength of the flexible substrate and the support corresponding to the peel prevention portion (hereinafter referred to as the "peel strength of the peel prevention portion") can be the same as the peel strength of the flexible substrate and the support in the functional layer formation region, and It may be higher or lower than the peel strength of the functional layer forming region. For example, when the support is reused, it is necessary to completely remove the frame-shaped flexible substrate remaining on the support after the flexible substrate including the functional layer is removed. Therefore, the peeling strength of the peeling prevention portion is preferably 500 N / m or less, and more preferably 200 N / m or less. If the peel strength of the peel prevention portion is higher than 500 N / m, there is a possibility that the removal of the peel prevention portion using, for example, a doctor blade or a jig may become difficult. If the peeling strength of the peeling prevention portion is less than 200 N / m, removal of the peeling prevention portion by vacuum suction or an adhesive becomes easy. In addition, a preferable lower limit of the peeling strength of the peeling prevention portion is the same as a lower limit of the peeling strength of the flexible substrate in the functional layer formation region, and is 0.1 N / m.

The method of forming the peeling prevention portion is not limited as long as the function of the peeling prevention portion is satisfied, and for example, the formation method described below is preferred.

First, one of the preferred examples of the method for forming the peeling prevention portion is The flexible substrate is provided with a plurality of resin layers. That is, the surface of the first resin layer formed on the support is covered with the second resin layer so that the flexible substrate has at least the first resin layer and the second resin layer, and the outer peripheral portion of the second resin layer and The support is adhered, and the outer peripheral portion of the second resin layer functions as a locking member to constitute a peeling prevention portion, thereby preventing the first resin layer from peeling from the support. Thereby, a functional layer is formed on the second resin layer, and after the flexible substrate in the functional layer formation region is cut from the peeling prevention portion, the first resin layer and the second resin layer from which the peeling prevention portion is removed become flexible. Substrate. As described above, the peeling strength between the flexible substrate and the support in the functional layer forming region where the functional layer is formed is 200 N / m or less and 0.1 N / m or more, and the ratio is formed at a position surrounding the functional layer forming region. In the functional layer formation region, it is more difficult for the flexible substrate to be peeled from the peeling prevention portion, so that a laminated structure suitable for manufacturing a display device including the functional layer on the flexible substrate can be manufactured. In addition, the film thickness of the second resin layer may be the same as the film thickness of the first resin layer, or may be smaller than the film thickness of the first resin layer. In this case, the total layer thickness of the first resin layer and the second resin layer laminated on the first resin layer is preferably larger than the layer thickness of the first resin layer on the peeling prevention portion. The average value of the film thickness is more preferably more than 1 μm.

In addition, another preferable example of the method for forming the peeling prevention portion is a portion where a part of a surface of the support that is in contact with the flexible substrate is roughened. That is, the support has a partially roughened surface at a position in contact with the flexible substrate on the outer peripheral side of the functional layer forming region, and the peripheral portion of the flexible substrate laminated in correspondence with the partially roughened surface is difficult to peel off. Here, roughening also includes forming a recessed portion on the surface of the support. In addition, as a roughening method, a well-known method can be used, and sand blasting and etching are preferable. When roughening by sandblasting, the roughness Ra of the peeling prevention portion is preferably 0.01 μm or more, more preferably 0.1 μm or more, and further preferably 10 μm or less, and more preferably 3 μm or less.

Furthermore, another preferable example of the method for forming the peeling prevention portion is to form a peeling prevention layer adhered to both the support and the flexible substrate. That is, on the outer peripheral side of the functional layer formation region, a peeling prevention layer is interposed between the peripheral edge portion of the flexible substrate and the support. Here, examples of the peeling prevention layer include tape, double-sided tape, polyimide, epoxy resin, acrylic resin, metal, and the like. From the viewpoints of heat resistance and workability, polyimide is preferably used. When using an adhesive tape or a double-sided tape, it is preferable that the film of an adhesive tape contains polyimide. The surface of the support may be coated with silver paste, aluminum paste, copper paste, etc., and then heated and sintered to form a metal on the surface of the support. If the peeling prevention layer is adhered to both the support and the flexible substrate, the peeling prevention layer may be formed before the flexible substrate is formed, or the peeling prevention layer may be formed after the flexible substrate is formed.

Further, another preferred example of the method for forming the peeling prevention portion is described below. Before the functional layer forming step, only the functional layer forming region of the flexible substrate formed in the flexible substrate forming step is corresponding. The UV laser beam is irradiated at the position, and the UV laser beam is not irradiated on the outer peripheral side of the functional layer forming region, thereby forming a region surrounding the functional layer compared to the peeling strength of the flexible substrate and the support from the functional layer forming region. The peeling prevention part with high peeling strength between the flexible substrate and the support at the position. A method is known in which a UV laser beam is irradiated after a functional layer is formed to remove a support from a flexible substrate (non-patent document 3, etc.). In this case, the UV laser beam passes through the flexible substrate. , May cause damage to the functional layer Performance. In particular, when the transmittance of the flexible substrate in the wavelength region of the UV laser beam is high, problems such as damage to the functional layer are likely to occur. Therefore, by irradiating a UV laser beam to a region where the functional layer is formed before the functional layer is formed, a display device can be manufactured without damaging the functional layer.

Furthermore, another preferable example of the peeling prevention portion is described below. The peeling prevention portion is formed of a part of a functional layer constituting material constituting a functional layer, and a flexible film formed on a support is covered with a film including the functional layer constituting material. A part of the surface of the flexible substrate and the surface of the support located on the outer periphery of the flexible substrate constitute a locking member including the functional layer constituent material to prevent the flexible substrate from peeling from the support. Preferably, the functional layer constituent material is continuously formed from the surface of the flexible substrate to the support, and the functional layer constituent material is adhered to the support, and a part of the constituent material of the functional layer is formed toward the functional layer. The outer peripheral side of the area protrudes. That is, the functional layer constituting material constituting the locking member includes the same material as at least one material forming the functional layer, and is connected to a functional film obtained by forming a film on a functional layer forming region of a flexible substrate. In the case of the functional layer, the functional film constitutes at least a part of the functional layer after the functional layer is formed and separated from the peeling prevention portion.

Here, the functional layer constituting material is a material constituting the final display device after the manufacturing process is completed. For example, the inorganic layer may include silicon oxide, aluminum oxide, silicon carbide, silicon oxycarbide, silicon carbonitride, nitrogen Barrier layers of inorganic oxide films such as silicon oxide and silicon oxynitride; or transparent conductive films such as ITO (tin-doped indium oxide), SnO, ZnO, IZO, and the like. In addition, functional layer constituent materials As the material, a color filter material such as a color resist and a black resist can be used. For example, in the case of a touch screen, a transparent conductive film such as ITO, SnO, ZnO, or IZO or a metal mesh is used as the inorganic layer. The term “continuously formed” means that the functional layer constituent material is formed by connecting the surface of the flexible substrate to the surface of the support via the end surface of the flexible substrate. The functional layer constituting material is not necessarily formed continuously on all sides around the flexible substrate. As the functional layer constituting material, when an inorganic layer is used, the functional layer constituting material also prevents moisture or a solvent from contacting the flexible substrate during the manufacturing process. Therefore, it is also one of the preferable forms to form the functional layer constituent material continuously on all sides around the flexible substrate.

Next, the support removal step will be described. In the step, after cutting the flexible substrate in the peeling prevention portion and the functional layer forming region, the support is removed from the flexible substrate. That is, after the functional layer of the flexible substrate is formed, the functional layer forming region of the flexible substrate provided with the functional layer is cut and separated from the peeling prevention portion to remove the support from the flexible substrate. A display device having a functional layer on a flexible substrate is obtained.

Regarding the separation of the flexible substrate and the peeling prevention portion in the functional layer formation region, it is only necessary to separate the flexible substrate in the functional layer formation region from the support without stressing the peeling prevention portion. The flexible substrate can be separated, or it can be separated together with the support. The means of separation is not particularly limited, and for example, a blade such as a knife or a roller blade can be used. Here, for example, after forming a barrier layer constituting a part of the functional layer, when using a blade to separate the functional layer formation area from the peeling prevention portion, in order to prevent the flexible substrate from being cut off from the cut surface when the flexible substrate is cut. The crack of the barrier layer can heat at least one of the flexible substrate and the blade. The appropriate heating temperature varies depending on the cutting method, the type of the flexible substrate and the barrier layer, and the like, and it is preferable to heat the glass substrate above the glass transition temperature of the flexible substrate. In addition, etching or laser using an alkaline aqueous solution, a plasma, or the like may be used as a means for separation.

The process for removing the support from the flexible substrate is not particularly limited. For example, a substrate 904 having a fixed functional layer forming region 906 as shown in FIG. 9 can be used. After the flexible substrate 902 is applied with a stress required for removal and the support 901 is removed, the functional layer forming region 906 is separated from the base 904. At this time, in order to prevent extension of the flexible substrate 902 or damage to the functional layer 903 caused by the stress applied to remove the support 901, the entire functional layer forming area 906 may be formed by suction, adhesion, or the like. The surface is fixed to the base 904. In the following method, when the functional layer forming region 906 is fixed to the base 904 by suction, the base 904 having fine holes connected from the inside of the base 904 to the surface of the base 904 may be used to reduce the pressure inside the base 904 and In a state where the functional layer forming region 906 is fixed to the surface of the base 904 by vacuum, the support 901 is removed from the flexible substrate 902, and then the pressure reduction inside the base 904 is released to separate the functional layer forming region 906 from the base 904. Here, the base 904 may be a resin or a metal such as stainless steel. Further, stress may be applied to an end portion of the laminated portion of the base body 904-functional layer forming region 906 to be separated from the end portion, or stress may be applied to the entire surface of the laminated portion of the base body 904-functional layer forming region 906, so that Separate the entire surface at approximately the same time. The surface shape of the base 904 may be a curved surface. In addition to the method using such a peeling device, a well-known method can be used, for example, an organic solvent can be used Agent or alkaline aqueous solution, or peeling using UV laser beam or heat.

After separating the flexible substrate 902 of the functional layer formation region 906 from the peeling prevention portion 905, the peeling prevention portion 905 can be removed from the support 901 first, and only the flexible substrate 902 of the functional layer formation region 906 remains on the support 901. Then, the support 901 is removed from the flexible substrate 902 of the functional layer forming region 906. When the support 901 is removed from the flexible substrate 902 constituting the functional layer forming region 906, it is necessary to fix the functional layer forming region 906 to a peeling device by means of adhesion, suction, etc., and apply the peeling to the functional layer forming region 906. Stress, but if the method of removing the peeling prevention portion 905 from the support 901 first is used, it is not necessary to perform precise position alignment for fixing the functional layer forming region 906 to the peeling device, and it is possible to efficiently use the The stress peeled from the peeling device is transferred to the functional layer forming region 906.

In addition, if the following method is used, when the support 901 is removed from the flexible substrate 902 constituting the functional layer formation region 906, it is easy to insert a scraper from the end surface of the flexible substrate 902 between the flexible substrate 902 and the support 901. The method is to separate the flexible substrate 902 of the functional layer formation region 906 from the peeling prevention portion 905, and then first remove the peeling prevention portion 905 from the support 901, and only the functional layer formation region 906 remains on the support 901. After the flexible substrate 902 is removed, the support 901 is removed from the flexible substrate 902 of the functional layer forming region 906. By using a doctor blade, the stress applied to the functional layer 903 during peeling can be reduced, and the functional layer 903 can be prevented from being damaged.

[Example]

Hereinafter, the content of the present invention will be described more specifically based on examples and the like, but the present invention is not limited to the scope of these examples. In addition, various evaluations are as follows get on.

"Peel strength"

Using a Strograph manufactured by Toyo Seiki Seisakusho Co., Ltd., the peel strength of the sample obtained by cutting the polyimide into a long shape was measured by a 180-degree peel test method, and evaluated.

"Thermal expansion coefficient"

A thermomechanical analysis (TMA) device was used to apply a load of 5.0 g to a polyimide film having a size of 3 mm × 15 mm, and a temperature from 30 ° C. to 260 ° C. at a constant heating rate (20 ° C./min) A tensile test was performed within the range, and the coefficient of thermal expansion (× 10 ^-6 / K) was measured based on the elongation of the polyimide film with respect to temperature.

"Transmittance"

Using a U4000-type spectrophotometer, the average value of the light transmittance of the polyfluorene film (50 mm × 50 mm) at 440 nm to 780 nm was determined.

"Peelability of Functional Layer Formation Area"

The laminated body of polyimide and a support was peeled by a human hand to remove the polyimide from the functional layer forming region. The case where peeling strength was strong and could not be peeled off by human hands was evaluated as ×, and the case where peeling was possible was evaluated as (Triangle | delta), it evaluated as (circle) when peeling is easy, and (circle) when peeling is extremely easy.

"Brick crack"

A 80 nm silicon nitride film was formed by Chemical Vapor Deposition (CVD), and a microscope manufactured by Yamato Scientific Co., Ltd. was used. Microscope KH-7700 to observe the occurrence of cracks. In a field of view of 10 mm square, when the number of cracks is 20 or more, the evaluation result is set to ×, and when the number of cracks is 10 or more and less than 20, the evaluation result is set to ○, and the A case where the number is less than 10 or no crack is set to ◎.

"Water impregnation"

The laminate of polyimide and a support was immersed in water at 20 ° C. for 1 hour, and then taken out of the water, and the presence or absence of peeling of the polyimide and the support was visually confirmed. When there is no peeling part, the evaluation result is set to ○, and when the entire surface is peeled or there is a peeling part, the evaluation result is set to x.

The raw materials, aromatic diamine compounds, and acid anhydride compounds of aromatic tetracarboxylic acids used in the synthesis of the polyamidic acid (polyimide precursor) solution treated in the following Synthesis Examples or Examples and Comparative Examples The solvents are shown below.

[Aromatic diamine compound]

． 1,4-phenylenediamine (PPD)

． 4,4'-diaminodiphenyl ether (DAPE)

． 2,2'-dimethyl-4,4'-diaminobiphenyl (mTB)

． 1,3-bis (4-aminophenoxy) benzene (TPER)

． 2,2-bis [4- (4-aminophenoxy) phenyl] propane (2,2-bis [4- (4-aminophenoxy) phenyl] propane, BAPP)

． 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB)

． 2-methoxy-4,4'-diaminophenylanilide (2'-Methoxy-4,4'-diaminobenzanilide, MABA)

[Anhydride compound of aromatic tetracarboxylic acid]

． Pyromellitic dianhydride (PMDA)

． 2,3,2 ', 3'-biphenyltetracarboxylic dianhydride (2,3,2', 3'-biphenyltetracarboxylic dianhydride, BPDA)

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

[Solvent]

． N, N-dimethylacetamide (DMAc)

(Synthesis example 1)

In a 300 ml separable flask under nitrogen flow, 8.0 g of PPD was added to the solvent DMAc while warming, and dissolved at 50 ° C. Then BPDA 22.0g was added. Then, the solution was continuously stirred at room temperature for 3 hours to perform a polymerization reaction to obtain a viscous polyamino acid solution a. In addition, the polyfluorenic acid solution a is heated to obtain a tea brown polyimide a.

(Synthesis example 2)

Under a stream of nitrogen, 18.9 g of TFMB was added to a solvent DMAc while stirring in a separable 500 ml flask, and dissolved. Then 6FDA 26.1g was added. Then, the solution was continuously stirred at room temperature for 5 hours to perform a polymerization reaction to obtain a viscous polyamino acid solution b. In addition, a transparent polyimide b is obtained by heating the polyfluorenic acid solution b.

(Synthesis example 3)

Under a stream of nitrogen, 26.3 g of TFMB was added to the solvent DMAc while stirring in a 500 ml separable flask, and dissolved. Subsequently, 16.1 g of PMDA and 1.8 g of 6FDA were added. Then, the solution was continuously stirred at room temperature for 5 hours to perform a polymerization reaction to obtain a viscous polyamino acid solution c. In addition, the polyfluorene acid solution c is heated to obtain a transparent polyfluorine imine c.

(Synthesis example 4)

Under a nitrogen stream, while stirring in a 500 ml separable flask, 29.1 g of BAPP was added to the solvent DMAc to dissolve it. Then added BPDA 3.23g and PMDA 13.6g. Then, the solution was continuously stirred at room temperature for 3 hours to perform a polymerization reaction to obtain a viscous polyamidic acid solution d. In addition, the polyfluorene acid solution d is heated to obtain a tea brown polyfluorene acid d.

(Synthesis example 5)

In a 2 L separable flask under nitrogen flow, 66.5 g of MABA and 34.5 g of DAPE were added to the solvent DMAc while dissolving. Then PMDA 92.6g was added. Then, the solution was continuously stirred at room temperature for 1.5 hours to perform a polymerization reaction to obtain a viscous polyamine solution e. In addition, the polyfluorene acid solution e is heated to obtain a tea-colored polyfluorene acid e.

(Synthesis example 6)

In a 500 ml separable flask under a stream of nitrogen, 20.3 g of mTB and 3.1 g of TPER were added to the solvent DMAc while dissolving. Then PMDA 18.4g and BPDA 6.2g were added. Then continue to stir the solution at room temperature for 4 hours A polymerization reaction was performed from time to time to obtain a viscous polyfluorinated acid solution f. In addition, the polyfluorene acid solution f is heated to obtain a yellow-brown polyfluorine imine f.

[Example 1]

A ferrite-based stainless steel foil having a thickness of 30 μm was used as a support, and a portion 10 mm from the ends of the four sides thereof was roughened by sand blasting. Then, in order to form a flexible substrate, a portion of 5 mm inward from the four sides of the stainless steel foil was left, and a polyamic acid solution a was applied so that the thickness after the heat treatment became 8 μm using an applicator. Next, using a hot air oven, heating at 100 ° C for 5 minutes, heating up to 4 ° C / min to 370 ° C, and then heating to 20 ° C / min to 500 ° C for 40 minutes, to obtain stainless steel as shown in Figure 1. A laminated body of the foil 101 and the polyimide a102. Here, in the laminated portion of the stainless steel foil 101 and the polyimide a102, a roughened portion corresponds to a peeling prevention portion, and a non-roughened portion corresponds to a functional layer formation region. As a result of the water immersion test of the laminated body, no peeling was found. After the four sides of the laminate were cut and removed from the ends by 12 mm, the remaining polyimide a102 (functional layer forming region) could be easily peeled from the support. The peel strength of the central portion (the remaining polyimide a102) of the laminate was 8 N / m, and the peel strength of the roughened portion (peel prevention portion) was 80 N / m. In addition, the evaluation results of the thermal expansion coefficient are shown in Table 1.

[Example 2]

An alkali-free glass having a thickness of 0.5 mm and 150 mm × 150 mm was used as a support, and the thickness of the heat-treated film was 3 μm by using an applicator. Polyurethane was coated on the support with a size of 140 mm × 140 mm. Amino acid solution b and use The hot air oven was heated and dried at 130 ° C and 150 ° C for 2 minutes to remove the solvent in the resin solution. Then, the polyamic acid solution b was applied at a size of 130 mm × 130 mm so that the thickness after the heat treatment became 22 μm, and heated at 130 ° C., 150 ° C., 200 ° C., and 250 ° C. for 30 minutes using a hot air oven. , And heated at 360 ° C. for 1 minute to obtain a laminate of glass 201 as a support and polyimide b 203 as a flexible substrate as shown in FIG. 2. Regarding the polyimide b 203 formed on the support 1, a portion having a thickness of 25 μm superimposed into a double layer corresponds to a functional layer forming region (having a size of 130 mm × 130 mm), and a thickness of 3 μm in its surrounding area. The exit portion corresponds to a peeling prevention portion (having an extension width of about 5 mm). As a result of the water immersion test of the laminated body, no peeling was found. After cutting into 4 sides of the polyimide b 203 at a position 8 mm from the end, both the central portion (the inner portion of the cut) and the peripheral portion (the outer portion of the cut) of the polyimide b 203 were cut. It can be easily peeled from the support. In addition, the evaluation results of peel strength, thermal expansion coefficient, and transmittance are shown in Table 1.

[Example 3]

An alkali-free glass having a thickness of 0.5 mm and 150 mm × 150 mm was used as a support, and the thickness of the heat-treated film was 22 μm using an applicator. Polyurethane was coated on the support with a size of 130 mm × 130 mm. The amine acid solution c was heated and dried at 120 ° C. for 5 minutes using a hot air oven to remove the solvent in the resin solution. Next, a layer of polyamic acid solution d was applied to cover the layer of polyamic acid solution c so that the thickness after the heat treatment became 3 μm at a size of 140 mm × 140 mm, and a hot air oven was used at 130 ° C, 150 ° C, 200 Heating at 250 ℃ for 30 minutes Then, it heated at 360 degreeC for 1 minute, and obtained the laminated body of the glass 301 and the polyimide c 304 and the polyimide d 305 as a support body shown in FIG. The laminate was formed of polyimide c 304 and polyimide d 305 to form a flexible substrate. The thickness of polyimide c 304 was 22 μm and polyimide d 305 was 3 μm in thickness. A portion of 25 μm corresponds to a functional layer formation area (having a size of 130 mm × 130 mm), and a projection having a thickness of 3 μm including polyimide d 305 around it is equivalent to a peeling prevention portion (having a projection width of about 5 mm) . As a result of the water immersion test of the laminated body, no peeling was found. After cutting into 4 sides of the polyimide containing polyimide c 304 and polyimide d 305 at a position 8 mm from the end, the central part of polyimide (the inner part of the incision) can be cut. It is extremely easy to peel off, and the peripheral part (the outer part of the cut) can also be peeled off. In addition, the evaluation results of peel strength and thermal expansion coefficient are shown in Table 1.

[Example 4]

An alkali-free glass having a thickness of 0.5 mm and 150 mm × 150 mm was used as a support, and the thickness of the heat-treated film was 25 μm using an applicator. Polyurethane was coated on the support with a size of 130 mm × 130 mm. The amino acid solution e was heated at 90 ° C for 10 minutes using a hot air oven. Next, the polyamic acid solution d was coated with a width of 6 mm on two parallel sides of the coated polyamino acid solution e so that the thickness after the heat treatment became 25 μm to cover the polyamino acid solution e and Both glass 401 were heated from 90 ° C. to 20 ° C./min to 360 ° C. using a hot air oven, thereby obtaining polyimide e 406 forming a flexible substrate as shown in FIG. 4 and glass as a support. Laminated body of 401. Visual confirmation of polyimide d 405 self-polymerizing polyimide The surface of the amine e 406 is continuously formed to the surface of the glass 401, and the polyimide d 405 is in contact with the polyimide e 406 and the glass 401 by about 3 mm, respectively. Here, the portion where the polyimide e 406 is in contact with the glass 401 and not in contact with the polyimide d 405 corresponds to the functional layer forming region, and the portion where the polyimide d 405 is in contact with the glass 401 corresponds to peeling Prevention Department. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into the incision at a position that is in contact with the polyimide d 405 and is 1 mm from both sides of the polyimide d 405, the central portion (the inner portion of the incision) can be easily peeled off. The amine d 405 can be peeled from the glass 401. In addition, the evaluation results of peel strength, thermal expansion coefficient, and barrier cracking are shown in Table 1.

[Example 5]

Using an alkali-free glass having a thickness of 0.5 mm and 150 mm × 150 mm as a support, the thickness of the heat-treated film was 2 μm using an applicator, and the support was 10 mm in length along the four sides of the glass 501 on the support. The polyamic acid solution d was applied in a wide width, and heated at 130 ° C. for 20 seconds using a hot air oven. Then, a polyamine solution f was applied in a size of 140 mm × 140 mm, and heated from 90 ° C. to 20 ° C./min to 360 ° C. using a hot air oven, thereby obtaining a polymer substrate forming a flexible substrate as shown in FIG. 5. A laminate of fluoreneimine f 507 and glass 501 as a support. At this time, the polyimide d 505 and the polyimide f 507 are connected to each other by about 5 mm. Here, a portion where the polyimide f 507 is in contact with the glass 501 corresponds to a functional layer formation region, and the polyimide d 505 corresponds to a peeling prevention portion. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into the 4 sides of the polyimide f 507 at a position 8 mm from the end, the central part of the polyimide (the inner part of the cut corresponds to the functional layer forming area) (Field) can be peeled off extremely easily, and the peripheral part (outer part of the cut) can also be peeled off. In addition, the evaluation results of peel strength, thermal expansion coefficient, and barrier cracking are shown in Table 1.

[Example 6]

An alkali-free glass having a thickness of 0.5 mm and 150 mm × 150 mm was used as a support, and a film thickness of 10 μm after heat treatment was applied with an applicator. Polyurethane was coated on the support with a size of 140 mm × 140 mm. The amine acid solution c was heated and dried at 130 ° C. using a hot air oven to remove the solvent in the resin solution. Then, after heating at 150 ° C, 200 ° C, and 250 ° C for a total of 30 minutes, and then heating at 360 ° C for 1 minute, a laminate of glass 601 as a support and polyimide c 604 as a flexible substrate was obtained. . Then, as shown in FIG. 6, a silicon nitride film 608 having a thickness of 80 nm was formed on the entire surface of the polyimide c 604 side of the laminate by chemical vapor deposition. Observation with a scanning electron microscope (SEM) confirmed that the barrier layer including the silicon nitride film 608 was a functional layer, and the surface of the polyimide c 604 was continuously formed on the surface of the glass 601. Here, a portion where the silicon nitride film 608 is formed on the polyimide c 604 corresponds to a functional layer formation region, and a portion where the silicon nitride film 608 is formed on the surface of the glass 601 corresponds to a peeling prevention portion. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into 4 sides of the polyimide c 604 at a position 3 mm from the end, the central part of the polyimide (the inner part of the cut) and the peripheral part (the outer part of the cut) can be extremely easily cut. To peel. In addition, the evaluation results of peel strength, thermal expansion coefficient, and barrier cracking are shown in Table 1.

[Example 7]

An alkali-free glass having a thickness of 0.5 mm and a size of 150 mm × 150 mm was used as a support, and the thickness of the heat-treated film was 25 μm using an applicator. Polyurethane was coated on the support at a size of 140 mm × 140 mm. The amine acid solution c was heated and dried at 130 ° C. for 5 minutes using a hot air oven to remove the solvent in the resin solution. Then, after heating at 150 ° C, 200 ° C, and 250 ° C for a total of 30 minutes, and then heating at 360 ° C for 1 minute, a laminated body of glass 701 as a support and polyimide c 704 as a flexible substrate was obtained. . Then, using the edge of a razor, cut 4 edges of the polyimide c 704 into the surface of the glass 701 at a position 5 mm from the end of the polyimide, and the polyimide and the 4 edges of the peripheral part were from the glass 701. Peel off. The peeling of the peripheral portion is extremely easy. Then, as shown in FIG. 7, a glass paste 709 was coated on the laminate so that the thickness after film formation became 5 μm to a size of 140 mm × 140 mm to cover the polyimide c 704 at 100 ° C. Heating was performed for 10 minutes, heating at 150 ° C for 2 minutes, heating at 380 ° C for 2 minutes, and heating at 400 ° C for 10 minutes. Observation by a scanning electron microscope confirmed that the barrier layer formed of the glass paste 709 was continuously formed from the surface of the polyimide c 704 to the surface of the glass 701. Here, a portion where the glass paste 709 is formed on the polyimide c 704 corresponds to a functional layer formation region, and a portion where the glass paste 709 is formed on the surface of the glass 701 corresponds to a peeling prevention portion. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into 4 sides of the polyimide c 704 at a position 3 mm from the end, the central part of the polyimide (the inner part of the cut) and the peripheral part (the outer part of the cut) can be extremely easily cut. To peel. In addition, the peel strength, thermal expansion coefficient, The evaluation results of the transmittance and barrier cracks are shown in Table 1.

[Example 8]

As the heat treatment after coating the polyamic acid solution b on the glass with two layers overlapped, heating at 130 ° C, 150 ° C, 200 ° C, and 250 ° C for a total of 30 minutes, and then heating at 360 ° C for 6 minutes, Except for this, a laminate of glass and polyfluorene imine b was obtained in the same manner as in Example 2. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into the 4 sides of the polyimide b at a position 8 mm from the end, the central part of the polyimide b (the inner part of the cut) and the peripheral part (the outer part of the cut) can be extremely easily cut. To peel. In addition, the evaluation results of peel strength, thermal expansion coefficient, and transmittance are shown in Table 1.

[Example 9]

As the heat treatment after the polyamic acid solution c was coated on the glass, the resin solution was removed by heating and drying at 130 ° C for 5 minutes, and then heating at 150 ° C, 200 ° C, and 250 ° C for a total of 30 minutes. A laminate of glass and polyfluorene imide c was produced in the same manner as in Example 6 except that it was heated at 320 ° C. for 1 minute, and a silicon nitride film was produced in the same manner as in Example 6. Observation by a scanning electron microscope confirmed that the barrier layer including the silicon nitride film was continuously formed from the surface of the polyimide c to the glass surface. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into the 4 sides of the polyimide at a position 3 mm from the end, the central part of the polyimide (inner part of the incision) and the peripheral part (outer part of the incision) can be easily peeled off. . In addition, the evaluation results of peel strength, thermal expansion coefficient, and barrier cracking are shown in Table 1.

[Example 10]

A laminate of glass and polyimide c was prepared in the same manner as in Example 6 except that the polyamic acid solution c was applied so that the film thickness after the heat treatment became 4 μm, and was the same as in Example 6. Way to make a silicon nitride film. Observation by a scanning electron microscope confirmed that the barrier layer including the silicon nitride film was continuously formed from the surface of the polyimide c to the glass surface. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into the 4 sides of the polyimide at a position 3 mm from the end, the central part of the polyimide (inner part of the incision) and the peripheral part (outer part of the incision) can be easily peeled off. . In addition, the evaluation results of peel strength and thermal expansion coefficient are shown in Table 1.

[Comparative Example 1]

A laminate of stainless steel foil and polyfluorene imine a was obtained in the same manner as in Example 1 except that roughening was not performed by sandblasting. As a result of the water immersion test of the laminate, polyimide a was peeled from the stainless steel foil. In addition, the evaluation results of peel strength and thermal expansion coefficient are shown in Table 1.

[Comparative Example 2]

A laminated body of stainless steel foil and polyfluorene imine a was obtained in the same manner as in Example 1 except that the heat treatment was performed in an oxidation-free oven. The oxygen concentration in the oven is about 1%. As a result of the water immersion test of the laminated body, no peeling was found. After the four sides of the laminate were cut and removed from the ends by 12 mm, the remaining polyimide a could not be peeled off by hand. The peel strength of the central part (residual polyimide a) of the laminate was 1800 N / m, and the peel strength of the peel prevention part was too high to be measured. Except this In addition, the evaluation results of the coefficient of thermal expansion are shown in Table 1.

[Comparative Example 3]

After a laminate of glass, polyimide c, and polyimide d was obtained in the same manner as in Example 3, polyimide c and polyimide d were not cut into the polyimide. Although peeling was possible, wrinkles were generated in polyimide c and polyimide d during peeling. In addition, the evaluation results of peel strength and thermal expansion coefficient are shown in Table 1.

[Comparative Example 4]

After obtaining a laminate of polyimide c 804 and glass 801 after peeling off four edges in the same manner as in Example 7, chemical vapor deposition was applied to the entire surface of the polyimide c 804 side of the laminate. A silicon nitride film 808 with a thickness of 80 nm was formed. As a result of observation by a scanning electron microscope, as shown in FIG. 8, the barrier layer including the silicon nitride film 808 was not continuously formed, and a silicon nitride film was not formed on the side of the polyimide c 804. 808. That is, there is no peeling prevention part. As a result of the water immersion test of the laminate, the polyimide c 804 was peeled from the glass 801. In addition, the evaluation results of peel strength, thermal expansion coefficient, transmittance, and barrier cracking are shown in Table 1.

[Comparative Example 5]

Except that no cuts were made in the four sides of the polyimide, the silicon nitride film was observed after the polyimide was peeled from the glass in the same manner as in Example 6. As a result, the polyimide was the same as in Example 6. There were no cracks in the corresponding portion of the central portion, but a large number of cracks were confirmed in a range of about 20 mm from the peripheral portion. In addition, the peel strength, heat The evaluation results of the expansion coefficient, transmittance, and barrier cracks are shown in Table 1.

[Comparative Example 6]

A laminate of glass and polyimide d was prepared in the same manner as in Example 6 except that the polyamic acid solution d was applied instead of the polyamic acid solution c, and the same procedure as in Example 6 was performed. Way to make a silicon nitride film. Observation by a scanning electron microscope confirmed that the barrier layer containing a silicon nitride film was continuously formed from the surface of polyimide d to the glass surface. As a result of the water immersion test of the laminated body, no peeling was found. After cutting into four sides of the polyimide at a position 3 mm from the end, the central part (the inner part of the cut) and the peripheral part (the outer part of the cut) of the laminate can be peeled off by hand, but Elongation and wrinkles were observed on the polyimide during peeling. In addition, the evaluation results of peel strength, thermal expansion coefficient, and barrier cracking are shown in Table 1.

[Comparative Example 7]

The polyamic acid solution c was coated on glass, and heated and dried at 130 ° C to remove the solvent in the resin solution, and then heated at 150 ° C, 200 ° C, and 250 ° C for a total of 30 minutes, and then heated at 270 ° C. Except for 1 minute, a laminated body of glass and polyimide c was produced in the same manner as in Example 6, and a silicon nitride film was produced in the same manner as in Example 6. Observation by a scanning electron microscope confirmed that the barrier layer including the silicon nitride film was continuously formed from the surface of the polyimide c to the glass surface. As a result of the water immersion test of the laminated body, no peeling was found. After incisions were made in the 4 sides of the laminated body at a position 3 mm from the end, the central part (the inside part of the notch) and the peripheral part (the outside part of the notch) of the laminated body could not be used by human hands. Peeling (peeling strength exceeds 200 N / m). In addition, the evaluation results of peel strength, thermal expansion coefficient, and transmittance are shown in Table 1.

[Comparative Example 8]

A polyamidic acid solution a was applied to another glass, and the same curing conditions as in Example 1 were used to obtain a film of polyimide a. An adhesive was applied to the 4 mm sides of the obtained polyimide a film at a distance of 5 mm from the end, and then the adhesive-coated surface was crimped to a ferrite stainless steel foil having a thickness of 30 μm. A laminate of stainless steel foil and polyimide a was obtained. As a result of the water immersion test of the laminate, water was immersed in the interface between the stainless steel foil and the polyimide, and protrusions of the polyimide from the stainless steel foil were found. In addition, the evaluation results of peel strength and thermal expansion coefficient are shown in Table 1.

[Example 11]

A laminate of glass and polyfluorene imide c was obtained in the same manner as in Example 6, and silicon nitride having a thickness of 80 nm was deposited on the entire surface of the polyimide c side of the laminate by chemical vapor deposition. Film formation. The silicon nitride film functions as a gas barrier layer that prevents moisture transmission, and a color filter layer is formed on an upper surface thereof. Then, a cut is made at a position of 3 mm from the end with respect to the four sides of the polyimide c, and then the central part of the polyimide c (the inner side of the cut) is located at a portion where the color filter layer is formed. (Partial) peeling, as a result, no cracks or the like were generated in the gas barrier layer or the color filter layer, the peeling was extremely easy, and a color filter substrate using polyimide c for a flexible substrate was obtained.

Claims (19)

A method for manufacturing a display device includes a flexible substrate forming step of applying a resin solution to a support to form a flexible substrate on the support; a functional layer forming step of forming a function on the flexible substrate. And a support removing step of removing the support from the flexible substrate having the functional layer formed thereon, and the method for manufacturing a display device is characterized in that the flexible substrate and the support are in a functional layer forming region where the functional layer is formed The peeling strength of the body is 200 N / m or less and 0.1 N / m or more, and a peeling prevention portion for preventing the flexible substrate from peeling off the support is formed at a position surrounding the functional layer forming region, and thus the function is not affected. In the layer formation region or the portion of the support corresponding to the peeling prevention portion, a partial chemical surface treatment is performed, or the portion of the support corresponding to the peeling prevention portion is not locally heated. In the support removing step, After separating the flexible substrate in the functional layer formation region from the peeling prevention portion, the support is removed from the flexible substrate having the functional layer, and the flexible substrate It is formed of two or more resin layers, and any one or more of the resin layers protrude toward the outer peripheral side of the functional layer formation region and are adhered to the support, thereby forming a peeling prevention portion, and the thickness of the peeling prevention portion It is thinner than the thickness of the flexible substrate in the functional layer formation region. A method for manufacturing a display device includes a flexible substrate forming step of applying a resin solution to a support to form a flexible substrate on the support; a functional layer forming step of forming a function on the flexible substrate. And a support removing step of removing the support from the flexible substrate having the functional layer formed thereon, and the method for manufacturing a display device is characterized in that the flexible substrate and the support are in a functional layer forming region where the functional layer is formed The peeling strength of the body is 200 N / m or less and 0.1 N / m or more, and a peeling prevention portion for preventing the flexible substrate from peeling off the support is formed at a position surrounding the functional layer forming region, and thus the function is not affected. In the layer formation region or the portion of the support corresponding to the peeling prevention portion, a partial chemical surface treatment is performed, or the portion of the support corresponding to the peeling prevention portion is not locally heated. In the support removing step, After separating the flexible substrate in the functional layer formation region from the peeling prevention portion, the support is removed from the flexible substrate having the functional layer, and the peeling prevention is performed. Formed by a part of the constituent material of the functional layer, forming the outer peripheral side of the release preventing part of the functional layer portion formed of a material constituting the functional layer extending to the region of the bonding and support member. The method for manufacturing a display device according to claim 1 or claim 2, wherein the peeling prevention portion is a surface of a support that is in contact with a flexible substrate on an outer peripheral side of a functional layer formation region. Roughened parts. The method for manufacturing a display device according to item 2 of the scope of patent application, wherein a part of a constituent material of the functional layer forming the peeling prevention portion is an inorganic layer formed of an inorganic material. The method for manufacturing a display device according to claim 1 or claim 2, wherein the peeling prevention portion is formed of a peeling prevention layer, and the peeling prevention layer is interposed on the outer peripheral side of the functional layer formation region between Between the flexible substrate and the support. A method for manufacturing a display device includes a flexible substrate forming step of applying a resin solution to a support to form a flexible substrate on the support; a functional layer forming step of forming a function on the flexible substrate. And a support removing step of removing the support from the flexible substrate having the functional layer formed thereon, and the method for manufacturing a display device is characterized in that the flexible substrate and the support are in a functional layer forming region where the functional layer is formed The peeling strength of the body is 200 N / m or less and 0.1 N / m or more, and a peeling prevention layer for preventing the flexible substrate from peeling off the support is formed by a peeling prevention layer, wherein the peeling prevention layer is formed across the The peripheral edge portion of the flexible substrate and the support are adhered in a manner such that the functional layer formation area or the portion of the support corresponding to the peeling prevention portion is not subjected to a local chemical surface treatment, or is not bonded to the support. The support portion corresponding to the peeling prevention portion is locally heated. In the support removing step, the flexible substrate and the peeling prevention portion are separated from each other in the functional layer formation region. After, since the functional layer includes a flexible substrate support is removed. The method for manufacturing a display device according to any one of claims 1, 2, and 6, wherein in the support removing step, the peeling prevention portion is removed from the support, and then the The flexible substrate of the functional layer removes the support. The method for manufacturing a display device according to any one of claims 1, 2, and 6, wherein a peeling strength of the flexible substrate and the support in the peeling prevention portion is 500 N / m the following. The method for manufacturing a display device according to any one of claims 1, 2, and 6, wherein before the functional layer forming step, only the ones formed in the flexible substrate forming step are formed. The ultraviolet laser beam is irradiated at the position corresponding to the functional layer formation region of the flexible substrate, thereby increasing the position around the functional layer formation region compared to the peeling strength of the flexible substrate and the support from the functional layer formation region. The peeling strength of the flexible substrate and the support forms a peeling prevention portion. The method for manufacturing a display device according to any one of claims 1, 2, and 6, wherein a thickness of the flexible substrate is 0.1 μm or more and 30 μm or less. The method for manufacturing a display device according to any one of claims 1, 2, and 6, wherein the flexible substrate includes polyimide. The method for manufacturing a display device according to item 11 of the scope of patent application, wherein in the step of forming the flexible substrate, after applying a resin solution of polyimide or a polyimide precursor to a support, Heat treatment is performed in an oxidizing environment to obtain a flexible substrate. The method for manufacturing a display device according to item 11 of the scope of patent application, wherein in the step of forming the flexible substrate, after applying a resin solution of polyimide or a polyimide precursor to a support, Heat treatment is performed at 280 ° C or higher to obtain a flexible substrate. The method for manufacturing a display device according to item 11 of the scope of patent application, wherein in the step of forming the flexible substrate, after applying a resin solution of polyimide or a polyimide precursor to a support, A flexible substrate is obtained by continuous heat treatment. The method for manufacturing a display device according to any one of the scope of claims 1, 2, and 6, wherein the display device is a touch screen. A resin solution containing a polyimide or a polyimide precursor for forming a flexible substrate, and used for a display device according to any one of claims 1 to 14 of a patent application range A manufacturing method, and forming an adhesive surface at least in contact with a support. A resin for a peel-off prevention layer, which constitutes a peel-off prevention layer used in the method for manufacturing a display device according to item 5 of the patent application scope. A resin solution for a peel-off prevention layer, which constitutes a peel-off prevention layer used in the method for manufacturing a display device according to item 5 of the scope of patent application. A peeling device for manufacturing a display device, which is used in the method for manufacturing a display device according to any one of claims 1 to 14 and has a substrate with a fixed functional layer forming region. It is characterized by applying the stress required to remove the support from the flexible substrate to the flexible substrate in the functional layer formation region from the base to remove the support.