A peeling layer having reduced peeling strength, a method for manufacturing the same, an information display element, and a method for manufacturing the same

Abstract

A method of manufacturing a peeling layer includes the steps of: preparing a support substrate; and forming a graphene oxide layer on the support substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to a peeling layer having a reduced peeling strength, a manufacturing method thereof, an information display element, and a manufacturing method thereof, and more particularly, to a peeling layer having a reduced peeling strength by adjusting the size of graphene oxide forming a peeling layer and adjusting the composition ratio of graphene oxide of different sizes to improve the coating rate of the graphene oxide layer, a manufacturing method thereof, an information display element, and a manufacturing method thereof. BACKGROUND

[0002] With the acceleration of the commercialization process of wearable devices such as smart glasses, the necessity and demand for flexible information display elements such as flexible displays are showing an increasing momentum.

[0003] In the manufacturing process of the flexible information display element, the flexible substrate is laminated on a support substrate, and then a manufacturing process is performed, and in the last process, a process of separating the flexible substrate from the support substrate is performed.

[0004] As the flexible substrate, polyimide is mainly used, and as the support substrate, a glass substrate is used. The method of forming the flexible substrate on the support substrate is as follows: polyimide varnish is applied to the support substrate, and is cured at a high temperature to form the flexible substrate on the support substrate. In this process, chemical bonding occurs between the polyimide and the support substrate, so that the adhesion between the support substrate and the flexible substrate increases, and thus it is difficult to separate them without an additional process.

[0005] To solve this problem, in the related art, a process of laser lift-off (LLO) is mainly used as a process of peeling the flexible substrate from the support substrate.

[0006] However, if a laser is used, there is a problem that an expensive laser lift-off device needs to be used, and it is not suitable for a large-area process. SUMMARY

[0007] Problems to be Solved by the Invention

[0008] The present application has been made to solve the above problems, and an object of the present application is to provide a peeling layer and a manufacturing method thereof, an information display element and a manufacturing method thereof, which form a graphene oxide layer as a peeling layer of a flexible information display element, and reduce the peeling strength of the graphene oxide layer by adjusting the size of graphene oxide forming the graphene oxide layer and adjusting the composition ratio of graphene oxide of different sizes.

[0009] Another object of the present application is to provide a peeling layer and a manufacturing method thereof, and an information display element and a manufacturing method thereof, which have the advantages of low manufacturing cost and applicability to a large-area process because an expensive laser peeling device is not required.

[0010] Another object of the present application is to provide a peeling layer and a manufacturing method thereof, and an information display element and a manufacturing method thereof, which have the advantages of low manufacturing cost and applicability to a large-area process because an expensive laser peeling device is not required.

[0011] Method for solving the problem

[0012] The manufacturing method of the peeling layer according to the present application for achieving the above object can include the steps of: preparing a support substrate; and forming a graphene oxide layer on the support substrate.

[0013] The peeling layer according to the present application can be manufactured by the manufacturing method of the peeling layer.

[0014] The manufacturing method of the information display element according to the present application for achieving the above another object can include the steps of: preparing a support substrate; forming a graphene oxide layer on the support substrate; forming a flexible substrate on the graphene oxide layer; and separating the support substrate and the flexible substrate.

[0015] The information display element according to the present application can be manufactured by the manufacturing method of the information display element.

[0016] Effects of the Invention

[0017] According to the present application, because an expensive laser peeling device is not required, the advantages of low manufacturing cost and applicability to a large-area process are achieved.

[0018] In addition, by adjusting the size of the graphene oxide forming the graphene oxide layer, and adjusting the composition ratio of graphene oxides of different sizes to improve the coating rate of the peeling layer on the support substrate, the chemical bonding between the support substrate, i.e., the glass substrate, and the polyimide can be prevented under the conditions of high-temperature exposure during the manufacturing of the flexible substrate, and high temperature and plasma during the manufacturing process of the display screen, so as to achieve the effect of reducing the peeling strength. Furthermore, because the peeling strength can be reduced while forming a thin film layer, the advantage of maintaining excellent level of light transmittance is achieved.

[0019] In addition, in the present application, graphene oxide dispersion liquid is micro- injected using electrospray, and a voltage can be applied, so that electrostatic attraction of the support substrate and the graphene oxide dispersion liquid can be induced, thereby forming a graphene oxide layer of a thin film. Thus, there is an advantage that a coating process of a cationic polymer electrolyte solution, which is conventionally performed before forming a graphene oxide layer, can be omitted. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flowchart of a manufacturing method of a peeling layer according to an embodiment of the present application;

[0021] Figure 2 is a flowchart of a manufacturing method of an information display element according to an embodiment of the present application;

[0022] Figure 3 is a flowchart of a flexible substrate forming process according to an embodiment of the present application;

[0023] Figure 4 is a cross-sectional view schematically illustrating each layer formed in a manufacturing method of an information display element according to an embodiment of the present application;

[0024] Figure 5 is a cross-sectional view schematically illustrating a separation process of a support substrate and a flexible substrate in a manufacturing process of an information display element according to an embodiment of the present application.

[0025] Reference signs:

[0026] S10: preparing a support substrate; S20: forming a graphene oxide layer; S30: forming a flexible substrate; S40: separating the support substrate and the flexible substrate; 10: support substrate; 20: peeling layer; 30: flexible substrate. DETAILED DESCRIPTION

[0027] Technical terms used in the present specification are used only to describe specific embodiments, and it is noted that the technical terms are not intended to limit the present application. In addition, technical terms used in the present specification are to be interpreted as meanings commonly understood by those skilled in the art to which the present application pertains, unless otherwise defined in the present specification, and are not to be interpreted as meanings of overgeneralization or meanings of overnarrowing. Furthermore, if technical terms used in the present specification are erroneous technical terms that cannot accurately describe the idea of the present application, the erroneous technical terms are to be replaced with technical terms that can be accurately understood by those skilled in the art and are to be interpreted.

[0028] In addition, general terms used in the present specification are to be interpreted according to the definition in a dictionary or according to the context, and are not to be interpreted as meanings of overnarrowing.

[0029] Further, the description used herein with respect to a singular includes the meaning of a plural, if the context does not otherwise require, in the present specification. Also, in the present application, the terms "comprise" or "include" or the like should not be interpreted as necessarily including all of the various constituents or various steps described in the specification, but should be interpreted as including some of the constituents or steps, or further including other constituents or steps.

[0030] Hereinafter, the present application will be described more specifically by way of examples, but the scope of the present application is not limited by the following examples.

[0031] Figure 1 is a flowchart of a manufacturing method of a release layer according to an embodiment of the present application.

[0032] Referring to Figure 1 The manufacturing method of a release layer according to an embodiment of the present application can include the steps of: a step of preparing a support substrate S10; and a step of forming a graphene oxide layer S20.

[0033] At this time, the support substrate can be a glass substrate, a polymer film, or a silicon wafer. However, the support substrate according to the present application is not necessarily limited thereto.

[0034] The support substrate can include a step of cleaning the support substrate and a step of surface-treating the support substrate.

[0035] At this time, the step of cleaning the support substrate can be as follows: immersing the support substrate in an ethanol solution, and then cleaning the support substrate using ultrasonic waves. Thereafter, the support substrate can be immersed in an isopropyl alcohol solution, and then cleaned using ultrasonic waves.

[0036] The support substrate which has passed through the cleaning process can be dried.

[0037] The step of forming a graphene oxide layer S20 can include a step of coating a graphene oxide dispersion solution on the support substrate.

[0038] At this time, the coating can be an electrospray method.

[0039] The electrospray coating can be performed at a spraying speed of 70 to 90 μL / min, an air pressure of 0.2 to 0.3 MPa, and a voltage of 9 kV or more. Preferably, the spraying speed can be 80 μL / min, the air pressure can be 0.25 MPa, and the voltage can be 10 kV.

[0040] The lower the spraying speed is below 70 μL / min, the less the number of water droplets sprayed due to the lack of volume, and thus there is a problem in that uniform coating is difficult. The higher the spraying speed is above 90 μL / min, the lower the spraying force compared to the volume, and thus there is a problem in that large water droplets are coated.

[0041] The lower the air pressure is below 0.2 MPa, the smaller the spraying force, and thus there is a problem in that large water droplets are coated. The higher the air pressure is above 0.3 MPa, the less the water droplets sprayed reach the substrate, and thus there is a problem in that the coating area is reduced.

[0042] The lower the voltage is below 9 kV, the larger the size of the water droplets sprayed, and when the voltage is 9 kV or more, fine spraying can be sufficiently performed.

[0043] The concentration of the graphene oxide dispersion liquid can be 0.01 to 0.02% by weight. Preferably, the concentration can be 0.01% by weight.

[0044] The lower the concentration is below 0.01% by weight, the lower the coating rate, and thus there is a problem in that the peeling strength is increased. The higher the concentration is above 0.02% by weight, the lower the light transmittance, and thus there is a problem.

[0045] According to an embodiment, the graphene oxide dispersion liquid can include first graphene oxide having a size of 50 um and second graphene oxide having a size of 1 um.

[0046] The graphene oxide dispersion liquid can include the first graphene oxide and the second graphene oxide in a ratio of 5:5 to 8:2.

[0047] When the content of the second graphene oxide is greater than that of the first graphene oxide, there is a problem in that the coating rate is decreased to increase the peeling strength.

[0048] According to another embodiment, the graphene oxide dispersion liquid can include graphene oxide having a size of 50 um. At this time, the graphene oxide dispersion liquid can include only graphene oxide having a size of 50 um without graphene oxide having a size of 1 um.

[0049] That is, in the present application, graphene oxide having a size of 50 um and graphene oxide having a size of 1 um can be included at the same time, and the composition range of graphene oxide having a size of 50 um and graphene oxide having a size of 1 um is set to a range of 5:5 to 8:2, or the coating rate of the graphene oxide layer can be increased by including only graphene oxide having a size of 50 um in the graphene oxide dispersion liquid, as a result of which an effect of reducing the peeling strength of the peeling layer can be obtained.

[0050] This improvement in the peeling strength can bring about the effect of reducing the peeling strength when peeling after the manufacturing information display element device process.

[0051] Figure 2 is a flowchart of a manufacturing method of an information display element according to an embodiment of the present application. Figure 3 is a flowchart of a flexible substrate forming process according to an embodiment of the present application.

[0052] Referring to Figure 2 A manufacturing method of an information display element according to an embodiment of the present application can include the steps of: a step S10 of preparing a support substrate; a step S20 of forming a graphene oxide layer; a step S30 of forming a flexible substrate; and a step S40 of separating the support substrate and the flexible substrate.

[0053] The constitution of the step S10 of preparing a support substrate and the step S20 of forming a graphene oxide layer is the same as the aforementioned contents described with reference to Figure 1 The description, and thus a detailed description is omitted.

[0054] Referring to Figure 3 The step S30 of forming a flexible substrate can include the steps of: a step S32 of applying a flexible substrate material; and a step S34 of heating the flexible substrate material.

[0055] In the step S32 of applying a flexible substrate material, the material applied on the graphene oxide layer can be selected from any one of the group consisting of polyimide, polyester, polyethylene, polycarbonate, polyethylene, polyvinyl ester, polyether sulfone, polyacrylate, polyethylene naphthalate, and polyethylene terephthalate. In the step of heating and curing the applied material, the curing conditions can vary depending on the applied material.

[0056] If the flexible substrate material is polyimide, since polyimide varnish is used, a step of heating and curing is required, and in the heating step S34, the temperature can be raised from room temperature to 350°C, at which time the temperature can be raised by 5°C per minute.

[0057] For example, heating can be performed at 100°C for 10 minutes, at 200°C for 30 minutes, and at 350°C for 30 minutes. Thereafter, natural cooling can be performed for about 3 hours.

[0058] In the step S40 of separating the support substrate and the flexible substrate, the support substrate and the flexible substrate can be separated using a physical force.

[0059] Figure 4 is a cross-sectional view schematically illustrating each layer formed in a manufacturing method of an information display element according to an embodiment of the present application. Figure 5is a cross-sectional view schematically illustrating a separation process of a support substrate and a flexible substrate in a manufacturing process of an information display element according to an embodiment of the present application. The description of Figure 4 and Figure 5 will be further explained in detail below with reference to the following examples.

[0060] Next, the process of manufacturing a peeling layer according to the present application will be explained in more detail through examples. The following examples are provided in order to more easily understand the present application, and thus the content of the present application is not limited by these examples.

[0061] <Raw materials used in the examples>

[0062] - bare Glass (Eagle XG, Corning Inc.)

[0063] - 0.01 wt% graphene oxide aqueous solution

[0064] Example 1

[0065] <Step of preparing a support substrate>

[0066] First, as a support substrate 10, Eagle XG glass (Corning Inc.) having a width and a length of 100 mm and a thickness of 0.5 mm was prepared.

[0067] The support substrate 10 was immersed in an ethanol solution, and then subjected to ultrasonic cleaning for about 15 minutes. Thereafter, the support substrate 10 was immersed in an isopropanol solution, and then subjected to ultrasonic cleaning for about 15 minutes. The support substrate 10, which was cleaned, was put into an oven, and dried at about 80°C for about 5 minutes.

[0068] <Step of forming a peeling layer>

[0069] Then, in order to form a graphene oxide layer, a 0.01 wt% graphene oxide (GO) dispersion liquid was prepared.

[0070] More specifically, graphene oxide was prepared using Hummer's method. Graphene oxide having a size of 1 um was controlled using an ultrasonic pulverization method, and graphene oxide having a size of 50 um was controlled using a shear stress method.

[0071] A 0.01 wt% graphene oxide dispersion liquid of 1 um size was prepared by taking 2 g of a graphene oxide solution of 0.5 wt% initial concentration of 1 um size and 98 g of distilled water, and then adding distilled water three times.

[0072] A 0.01 wt% graphene oxide dispersion liquid of 50 um size was prepared by taking 2 g of a graphene oxide solution of 0.5 wt% initial concentration of 50 um size and 98 g of distilled water, and then adding distilled water three times.

[0073] After setting the following conditions in the electrospray device, the graphene oxide was coated on the support substrate.

[0074] Table 1

[0075]

[0076] In the present application, since the coating is performed using a graphene oxide dispersion liquid in which graphene oxide of 1 um size and graphene oxide of 50 um size are mixed to increase the coating rate of the graphene oxide layer on the support substrate, an effect of reducing the peeling strength of the peeling layer can be obtained.

[0077] In addition, by using the electrospray device to coat the graphene oxide, an advantage of omitting the coating process of the cationic polymer electrolyte solution, which is performed before the formation of the graphene oxide layer in the related art, can be obtained. Further, since the cationic polymer layer is not formed, an advantage of being able to prevent the reduction in light transmittance caused by the coated cationic polymer can be obtained.

[0078] Through the above-described process, the formation of the peeling layer 20 according to the present application is completed.

[0079] <Step of forming a flexible substrate>

[0080] Next, a process of manufacturing an information display element according to the present application will be described in detail.

[0081] After the above-mentioned peeling layer manufacturing process is completed, a polyimide (PI) varnish is coated on the graphene oxide layer using a coater until a thickness of 8 um is reached.

[0082] A heat treatment is performed at 100°C for 10 minutes, at 200°C for 30 minutes, and at 350°C for 30 minutes to improve imidization. At this time, the temperature increase rate in each temperature step is preferably 5°C / min.

[0083] The formation of the flexible substrate 30 is completed by coating the polyimide varnish and cooling it for 3 hours after the heating process.

[0084] <Step of manufacturing the information display element>

[0085] Subsequently, a layer 40 including a TFT layer, an organic light emitting layer, and an encapsulation layer is formed, and a step of separating the support substrate 10 and the flexible substrate 30 is performed.

[0086] In the present application, the step of separating the support substrate 10 and the flexible substrate 30 is performed by separating the flexible substrate 30 from the peeling layer 20, and thus the manufacturing process of the information display element according to the present application is also completed.

[0087] Examples 2 and 3

[0088] Examples 2 and 3 are implemented using the same process as Example 1, except that the step of mixing the 0.01 wt% graphene oxide dispersion of 50 um size and the 0.01 wt% graphene oxide dispersion of 1 um size in a ratio of 5:5 in the <Step of forming the peeling layer> of Example 1 is changed to mixing in a ratio of 7:3 and 8:2, respectively.

[0089] Example 4

[0090] Example 4 is implemented using the same process as Example 1, except that the step of mixing the 0.01 wt% graphene oxide dispersion of 50 um size and the 0.01 wt% graphene oxide dispersion of 1 um size in a ratio of 5:5 in the <Step of forming the peeling layer> of Example 1 is changed to using only the 0.01 wt% graphene oxide dispersion of 50 um size without using the 0.01 wt% graphene oxide dispersion of 1 um size.

[0091] Comparative Examples 1 and 2

[0092] Comparative Examples 1 and 2 are implemented using the same process as Example 1, except that the step of mixing the 0.01 wt% graphene oxide dispersion of 50 um size and the 0.01 wt% graphene oxide dispersion of 1 um size in a ratio of 5:5 in the <Step of forming the peeling layer> of Example 1 is changed to mixing in a ratio of 3:7 and 2:8, respectively.

[0093] Comparative Example 3

[0094] Comparative Example 3 was carried out using the same process as Example 1, except that the step of mixing 0.01 wt % of 50 μm graphene oxide dispersion and 0.01 wt % of 1 μm graphene oxide dispersion in a ratio of 5:5 when preparing the graphene oxide dispersion in the <Step of Forming a Peeling Layer> of Example 1 was replaced by using only 0.01 wt % of 1 μm graphene oxide dispersion without including 0.01 wt % of 50 μm graphene oxide dispersion.

[0095] Experimental Example 1

[0096] To measure the peel strength of the flexible substrate 30 (i.e., a polyimide substrate) formed on the support substrate 10 prepared in the examples described above, vertical peel strength was measured using an AMETEK (LS-1) film adhesion tester using the ASTM D3330 test method. The results are shown in Table 2.

[0097] Experimental Example 2

[0098] To measure the transmittance of the samples described in this example, Eagle XG glass (Corning) with a width and length of 100 mm and a thickness of 0.5 mm was used for calibration. Three measurements were performed for each sample, and the average value was obtained. The transmittance measurement instrument used was a DENSHOKU (NDH-7000). The results are shown in Table 2.

[0099] Table 2

[0100]

[0101]

[0102] As shown in Table 2 above, the peel strength varies with the composition ratio of the 50 μm graphene oxide dispersion to the 1 μm graphene oxide dispersion. The following effect can be observed: as the content of the 50 μm graphene oxide dispersion increases, the coating rate increases, thereby reducing the peel strength.

[0103] This is because, for the 1 um-sized graphene oxide dispersion liquid of small size, since it has a size significantly smaller than that of the water droplet, only the portion of the water droplet edge is coated with the graphene oxide dispersion liquid during the water evaporation, and thus, there is much overlap between the plates, resulting in that the coating can be performed only locally. In contrast, for the 50 um-sized graphene oxide dispersion liquid of large size, since it has a size corresponding to that of the water droplet, the entire area of the water droplet on which the graphene oxide is dispersed can be coated when the water droplet is coated on the substrate, and thus, compared to the graphene oxide dispersion liquid of small size, the graphene oxide dispersion liquid of large size can be uniformly coated on the entire area, thereby increasing the coating rate.

[0104] In addition, in terms of the light transmittance, excellent light transmittance results were obtained in all the examples.

[0105] Experimental Example 3

[0106] In order to measure the peeling strength of the flexible substrate 30, i.e., the polyimide substrate, formed on the support substrate 10 prepared in the comparative example, the vertical peeling strength was measured in a film adhesion test device by the test method of the specification ASTM D3330. The test instrument used was AMETEK (LS1). The results are shown in Table 3.

[0107] Experimental Example 4

[0108] In order to measure the light transmittance according to the comparative example, after calibration using Eagle XG glass (Corning Inc.) having a width and length of 100 mm and a thickness of 0.5 mm, the light transmittance was measured. Three measurements were performed for each sample to obtain an average value. At this time, the light transmittance measuring device used was DENSOKU (NDH-7000). The results are shown in Table 3.

[0109] Table 3

[0110]

[0111] As shown in Table 3 above, the peeling strength varies depending on the composition ratio of the 50 um-sized graphene oxide dispersion liquid and the 1 um-sized graphene oxide dispersion liquid, and it can be observed that the more the content of the 1 um-sized graphene oxide dispersion liquid, the higher the peeling strength.

[0112] The above has been described with respect to specific preferred embodiments of the present application, but the present application is not limited to the above-described specific embodiments, and various modified embodiments can be made by those skilled in the art without departing from the spirit of the present application claimed in the claims, and such modified embodiments are intended to be included within the scope recited in the claims.

Claims

1. A method for manufacturing a peeling layer, characterized by, The manufacturing method of the peeling layer includes the following steps: a step of preparing a support substrate; and a step of forming a graphene oxide layer on the support substrate, the step of forming the graphene oxide layer includes: a step of applying a graphene oxide dispersion liquid to the support substrate, the graphene oxide dispersion liquid includes first graphene oxide and second graphene oxide, the first graphene oxide has a size of 50 um, and the second graphene oxide has a size of 1 um, the graphene oxide dispersion liquid contains the first graphene oxide and the second graphene oxide at a ratio of 5:5 to 8:

2.

2. The method of manufacturing a release layer according to claim 1, wherein the step of applying the graphene oxide dispersion liquid includes: a step of applying the graphene oxide dispersion liquid to the support substrate by electro-spraying under the conditions that the spraying speed is 70-90 μL / min, the air pressure is 0.2-0.3 MPa, and the voltage is 9 kV or higher.

3. The manufacturing method of the peeling layer according to claim 2, wherein the spraying speed is 80 μL / min, the air pressure is 0.25 MPa, and the voltage is 10 kV.

4. The manufacturing method of the peeling layer according to claim 1, wherein the concentration of the graphene oxide dispersion liquid is 0.01-0.02% by weight.

5. The manufacturing method of the peeling layer according to claim 4, wherein the concentration of the graphene oxide dispersion liquid is 0.01% by weight.

6. A peeling layer, wherein the peeling layer is manufactured according to the manufacturing method of any one of claims 1 to 5.

7. A method for manufacturing an information display element, characterized by The manufacturing method of the information display element includes the following steps: a step of preparing a support substrate; a step of forming a graphene oxide layer on the support substrate, a step of forming a flexible substrate on the graphene oxide layer; and a step of separating the support substrate and the flexible substrate, the step of forming the graphene oxide layer includes: a step of applying a graphene oxide dispersion liquid to the support substrate, the graphene oxide dispersion liquid includes first graphene oxide and second graphene oxide, the first graphene oxide has a size of 50 um, and the second graphene oxide has a size of 1 um, the graphene oxide dispersion liquid contains the first graphene oxide and the second graphene oxide at a ratio of 5:5 to 8:

2.

8. The method of producing an information display element according to claim 7, wherein the step of applying the graphene oxide dispersion liquid includes: a step of applying the graphene oxide dispersion liquid to the support substrate by electro-spraying under the conditions that the spraying speed is 70-90 μL / min, the air pressure is 0.2-0.3 MPa, and the voltage is 9 kV or higher.

9. The manufacturing method of the information display element according to claim 8, wherein the spraying speed is 80 μL / min, the air pressure is 0.25 MPa, and the voltage is 10 kV.

10. The manufacturing method of the information display element according to claim 7, wherein the concentration of the graphene oxide dispersion liquid is 0.01-0.02% by weight.

11. The manufacturing method of the information display element according to claim 10, wherein the concentration of the graphene oxide dispersion liquid is 0.01% by weight. The concentration of the graphene oxide dispersion liquid is 0.01 wt%.

12. The method of producing an information display element according to claim 7, wherein The step of forming the flexible substrate includes the steps of: coating a substance selected from the group consisting of polyimide, polyester, polycarbonate, polyethylene, polyvinyl ester, polyether sulfone, polyacrylate, polyethylene naphthalate, and polyethylene terephthalate on the graphene oxide layer; and heating the coated substance.

13. The method of manufacturing an information display element according to claim 12, wherein the step of heating the coated substance is heating the coated substance from room temperature to 350°C at a temperature increase of 5°C per minute.

14. An information display element, wherein the information display element is manufactured according to the method of manufacturing an information display element according to any one of claims 7 to 13.

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