Protective film, display device including the same, and method of manufacturing the display device

Abstract

The invention relates to a protective film, a display device including the same, and a method of manufacturing the same. A protective film included in a display device is manufactured by preparing graphene oxide particles in a powder state, adjusting the size of the graphene oxide particles to achieve preselected dispersibility in a carbon nanocomposite, and mixing the adjusted size graphene oxide particles with a light-curable resin.

Description

Technical Field

[0001] Implementations of the inventive concept generally relate to a protective film, a display device including the protective film, and a method of manufacturing the display device. Background Art

[0002] Display devices can be divided into rigid display devices and flexible display devices. Flexible display devices include bendable display devices, curved display devices, foldable display devices, and rollable display devices.

[0003] The flexible display device may include a flexible substrate (eg, a plastic substrate) and a protective film supporting the flexible substrate. The protective film is made of plastic and is generally implemented in the form of a PET film. Summary of the invention

[0004] Embodiments provide a protective film.

[0005] Embodiments provide a display device including a protective film.

[0006] Embodiments provide a method of manufacturing a display device.

[0007] A protective film according to an embodiment may include: a photocurable resin; and a carbon nanocomposite material including graphene oxide particles having a size (also referred to as “particle size”) adjusted to achieve a preselected dispersibility in the carbon nanocomposite material.

[0008] In an embodiment, the size of the graphene oxide particles may be about 0.1 μm to about 2 μm.

[0009] In an embodiment, the weight ratio of the carbon nanocomposite material may be about 0.05 wt % to about 20 wt % based on the total weight of the photocurable resin.

[0010] In an embodiment, the carbon nanocomposite may further include carbon black.

[0011] In an implementation, the photocurable resin may be cured by light, and may have a viscosity of about 10 cPS to about 500 cPS.

[0012] A display device according to an embodiment may include: a lower protective film including a photocurable resin and a carbon nanocomposite material, wherein the carbon nanocomposite material includes graphene oxide particles; a flexible substrate disposed on the lower protective film; a transistor layer disposed on the flexible substrate; and an emission layer disposed on the transistor layer.

[0013] In an embodiment, the size of the graphene oxide particles may be about 0.1 μm to about 2 μm.

[0014] In an embodiment, the flexible substrate may include: a flat region including a first flat region and a second flat region; and a bending region between the first flat region and the second flat region. The lower protection film may overlap with the flat region and may not overlap with the bending region.

[0015] In an implementation, the display device may further include: a plurality of glass patterns disposed below the flexible substrate, and the lower protective film may cover the plurality of glass patterns.

[0016] The method of manufacturing a display device according to an embodiment may include: forming a protective film; forming a display panel on a flexible substrate; and forming a protective film under the flexible substrate. Forming the protective film may include: preparing graphene oxide particles in a powder state; adjusting the size of the graphene oxide particles; and forming a composite ink by mixing the graphene oxide particles having the adjusted size with a photocurable resin.

[0017] In an embodiment, the size of the graphene oxide particles having the adjusted size may be about 0.1 μm to about 2 μm.

[0018] In an embodiment, the size of the graphene oxide particles in a powder state may be about 20 μm to about 40 μm.

[0019] In an embodiment, the method may further include dispersing graphene oxide particles in a powder state in water.

[0020] In an embodiment, the size of the graphene oxide particles dispersed in water may be about 5 μm to about 15 μm.

[0021] In embodiments, the size of the graphene oxide particles may be adjusted by ultrasonic treatment of the graphene oxide particles.

[0022] In an embodiment, the method may further include removing water from the graphene oxide particles having the adjusted size.

[0023] In an embodiment, the protective film may include a first lower protective film and a second lower protective film having different physical properties from each other, the first lower protective film may be formed by ejecting a first composite ink from a first inkjet head, and the second lower protective film may be formed by ejecting a second composite ink having physical properties different from those of the first composite ink from a second inkjet head.

[0024] In an embodiment, the first lower protective film and the second lower protective film may overlap each other when the flexible substrate is in a bent state.

[0025] Therefore, the protective film according to an embodiment of the present invention may include a polymer resin (e.g., an acrylic photocurable resin) and graphene oxide (GO) particles of adjusted particle size. The size of the graphene oxide particles can be adjusted by ultrasonic treatment (e.g., a tip ultrasonic treatment process and / or a water bath ultrasonic treatment process), and then the dispersibility in the polymer resin can be improved by a freeze-drying process. Since the protective film includes both an organic material (e.g., a polymer resin) and an inorganic material (e.g., graphene oxide particles), the heat dissipation function of the protective film can be improved and the strength of the protective film can be improved.

[0026] In addition, the protective film can be formed by an inkjet printing process using ink. Accordingly, protective films of various structures can be appropriately formed as needed. For example, the shape of the protective film can be formed to correspond to the pattern of the patterned flexible substrate. In addition, since the physical properties of the manufactured composite ink are different, the protective film can be formed in a stacked structure, or the protective film can be formed separately for each zone. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the inventive concept and are incorporated in and constitute a part of this specification and, together with the description, illustrate embodiments of the inventive concept.

[0028] Figure 1 is a cross-sectional view illustrating a display device according to an embodiment of the present invention.

[0029] Figure 2 The explanation is included in Figure 1 A cross-sectional view of a display panel and a sensing layer in a display device.

[0030] Figure 3 is to explain that manufacturing includes Figure 1 A flow chart of a method for providing a protective film in a display device.

[0031] Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 It is an interpretation Figure 3 Graph of the method.

[0032] Figures 9 to 22 is to explain the application of Figure 3 FIG. 1 is a diagram of an example of a method for manufacturing a protective film. DETAILED DESCRIPTION

[0033] Illustrative and non-limiting embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

[0034] For ease of explanation, spatially relative terms such as "on" and "above" may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figure. It will be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure is turned over, the elements described as "below" or "below" other elements or features will then be oriented "above" other elements or features. Therefore, the exemplary terms "below" and "below" may include both above and below orientations. The device can be oriented in other ways (e.g., rotated 90 degrees or in other orientations) and the spatially relative descriptors used in this article should be interpreted accordingly.

[0035] In the present disclosure, when the particles are spherical, "diameter or size" indicates the particle diameter or average particle diameter, and when the particles are non-spherical, "diameter or size" indicates the major axis length or average major axis length. The diameter (or size) of the particles can be measured using a scanning electron microscope or a particle size analyzer. As a particle size analyzer, for example, a HORIBA, LA-950 laser particle size analyzer can be used. When the size of the particles is measured using a particle size analyzer, the average particle diameter (or size) is referred to as D 50 . D 50 Refers to the average diameter (or size) of particles whose cumulative volume corresponds to 50% by volume in a particle size distribution (e.g., cumulative distribution), and refers to the value of the particle size corresponding to 50% from the smallest particle size when the total number of particles is 100% in a distribution curve accumulated in the order from the smallest particle size to the largest particle size.

[0036] As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art will recognize. "Substantially," as used herein, includes the recited value, and means within the range of acceptable deviations of the particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "substantially" may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0037] Furthermore, any numerical range set forth herein is intended to include all sub-ranges of the same numerical precision falling within the range set forth. For example, the range of "1.0 to 10.0" is intended to include between the minimum value 1.0 set forth and the maximum value 10.0 set forth (and including 1.0 and 10.0), that is, all sub-ranges with a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits falling therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits falling therein. Accordingly, the applicant reserves the right to modify this specification (including claims) to explicitly set forth any sub-range falling within the range explicitly set forth herein.

[0038] Figure 1 is a cross-sectional view illustrating a display device according to an embodiment of the present invention. Figure 2 The explanation is included in Figure 1 A cross-sectional view of a display panel and a sensing layer in a display device.

[0039] refer to Figure 1 According to an embodiment of the present invention, the display device DD may include a first lower protective film LPF1, a second lower protective film LPF2, a flexible substrate SUB, a display panel PNL, a sensing layer SL, and an upper protective film UPF. The display panel PNL may include a transistor layer TL, an emission layer LEDL, and a thin film encapsulation layer TFE.

[0040] The flexible substrate SUB may include a transparent or opaque material. In addition, the flexible substrate SUB may be formed of a flexible material. In an embodiment, examples of materials that can be used as the flexible substrate SUB may include ultra-thin tempered glass (UTG), glass, quartz, and plastic. These can be used alone or in combination with each other. In addition, the flexible substrate SUB may be composed of a single layer or a plurality of layers combined with each other.

[0041] In an embodiment, the flexible substrate SUB may be divided into a flat area FA and a bending area BA, and the bending area BA may be bent from the flat area FA.

[0042] The first lower protective film LPF1 and the second lower protective film LPF2 may be disposed under the flexible substrate SUB in an unfolded state and may overlap the flat area FA in a folded state. The first lower protective film LPF1 and the second lower protective film LPF2 may support the flexible substrate SUB.

[0043] refer to Figure 1 and Figure 2The transistor layer TL may be disposed on the flexible substrate SUB. The transistor layer TL may include a buffer layer BFR, an active pattern ACT, a first insulating layer ILD1, a first gate electrode GAT1, a second insulating layer ILD2, a second gate electrode GAT2, a third insulating layer ILD3, a first connection electrode CE1, a second connection electrode CE2, and a fourth insulating layer ILD4.

[0044] The buffer layer BFR may be disposed on the flexible substrate SUB. In an embodiment, the buffer layer BFR may be formed of an inorganic insulating material. Examples of materials that can be used as inorganic insulating materials may include silicon oxide, silicon nitride, and silicon oxynitride. These can be used alone or in combination with each other. The buffer layer BFR may prevent atoms (e.g., metal atoms) or impurities from diffusing from the flexible substrate SUB to the active pattern ACT. In addition, the buffer layer BFR may control the rate of heat supply during the crystallization process of forming the active pattern ACT.

[0045] The active pattern ACT may be disposed on the buffer layer BFR. In an embodiment, the active pattern ACT may be formed of a silicon semiconductor material or an oxide semiconductor material. Examples of silicon semiconductor materials that can be used as the active pattern ACT may include amorphous silicon and polycrystalline silicon. Examples of oxide semiconductor materials that can be used as the active pattern ACT may include InGaZnO (IGZO), InSnZnO (ITZO), and the like. In addition, the oxide semiconductor material may further include indium (In), gallium (Ga), tin (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), titanium (Ti), and zinc (Zn). These can be used alone or in combination with each other.

[0046] The first insulating layer ILD1 may cover the active pattern ACT and may be disposed on the buffer layer BFR. In an embodiment, the first insulating layer ILD1 may be formed of an insulating material. Examples of insulating materials that can be used as the first insulating layer ILD1 may include silicon oxide, silicon nitride, and silicon oxynitride. These can be used alone or in combination with each other.

[0047] The first gate electrode GAT1 may be disposed on the first insulating layer ILD1. In an embodiment, the first gate electrode GAT1 may be formed of a metal, an alloy, a metal nitride, a conductive metal oxide, a transparent conductive material, etc. Examples of materials that can be used as the first gate electrode GAT1 may include silver (Ag), an alloy containing silver, molybdenum (Mo), an alloy containing molybdenum, aluminum (Al), an alloy containing aluminum, aluminum nitride (AlN), tungsten (W), tungsten nitride (WN), copper (Cu), nickel (Ni), chromium (Cr), chromium nitride (CrN), titanium (Ti), tantalum (Ta), platinum (Pt), scandium (Sc), indium tin oxide (ITO), indium zinc oxide (IZO), etc. These can be used alone or in combination with each other.

[0048] The second insulating layer ILD2 may be disposed on the first insulating layer ILD1. The second insulating layer ILD2 may cover the first gate electrode GAT1. In an implementation, the second insulating layer ILD2 may be formed of an insulating material.

[0049] The second gate electrode GAT2 may be disposed on the second insulating layer ILD2. In an implementation, the second gate electrode GAT2 may be formed of a metal, an alloy, a metal nitride, a conductive metal oxide, a transparent conductive material, or the like.

[0050] The third insulating layer ILD3 may be disposed on the second insulating layer ILD2. The third insulating layer ILD3 may cover the second gate electrode GAT2. In an implementation, the third insulating layer ILD3 may be formed of an insulating material.

[0051] The first and second connection electrodes CE1 and CE2 may be disposed on the third insulating layer ILD3 and may be connected to the active pattern ACT. In an implementation, the first and second connection electrodes CE1 and CE2 may be formed of metal, alloy, metal nitride, conductive metal oxide, transparent conductive material, or the like.

[0052] The fourth insulating layer ILD4 may be disposed on the third insulating layer ILD3. The fourth insulating layer ILD4 may cover the first connection electrode CE1 and the second connection electrode CE2. In an embodiment, the fourth insulating layer ILD4 may be formed of an insulating material. Examples of organic materials that can be used as the fourth insulating layer ILD4 may include photoresist, polyacrylic resin, polyimide resin, and acrylic resin. These can be used alone or in combination with each other.

[0053] The emission layer LEDL may include a pixel electrode PE, a pixel defining layer PDL, an organic emission layer EL, and a common electrode CE.

[0054] The pixel electrode PE may be disposed on the fourth insulating layer ILD4 and may be connected to the second connection electrode CE2. In an implementation, the pixel electrode PE may be formed of metal, alloy, metal nitride, conductive metal oxide, transparent conductive material, or the like.

[0055] The pixel defining layer PDL may be disposed on the pixel electrode PE and may cover the end of the pixel electrode PE. In some embodiments, the pixel defining layer PDL may be formed of an organic material. Examples of organic materials that can be used as the pixel defining layer PDL may include photoresists, polyacrylic resins, polyimide resins, and acrylic resins. These can be used alone or in combination with each other.

[0056] The organic emission layer EL may be disposed on the pixel electrode PE, and the common electrode CE may be disposed on the organic emission layer EL. The organic emission layer EL may emit light based on a voltage difference between the pixel electrode PE and the common electrode CE.

[0057] The thin film encapsulation layer TFE may include a first inorganic layer IL1, an organic layer OL, and a second inorganic layer IL2. The thin film encapsulation layer TFE may protect the organic emission layer EL from moisture and / or oxygen.

[0058] The first inorganic layer IL1 may be disposed on the common electrode CE. In an embodiment, the first inorganic layer IL1 may be formed of an inorganic insulating material. Examples of inorganic insulating materials that can be used as the first inorganic layer IL1 may include silicon oxide, silicon nitride, and silicon oxynitride. These can be used alone or in combination with each other.

[0059] The organic layer OL may be disposed on the first inorganic layer IL1. In some embodiments, the organic layer OL may be formed of an organic insulating material. Examples of organic insulating materials that can be used as the organic layer OL may include photoresists, polyacrylic resins, polyimide resins, and acrylic resins. These can be used alone or in combination with each other.

[0060] The second inorganic layer IL2 may be disposed on the organic layer OL. In an embodiment, the second inorganic layer IL2 may be formed of an inorganic insulating material.

[0061] The sensing layer SL may be disposed on the second inorganic layer IL2. In an embodiment, the sensing layer SL may be a touch panel that senses a user's touch.

[0062] Reference again Figure 1 , an upper protection film UPF may be disposed on the sensing layer SL. The upper protection film UPF may protect the sensing layer SL, the display panel PNL, and any other layers in the display device DD from external impact.

[0063] In an implementation, the first lower protection film LPF1, the second lower protection film LPF2, and the upper protection film UPF may include a polymer resin and a carbon nanocomposite material.

[0064] In an embodiment, the polymer resin may include a light-curable resin that is cured by light. For example, the light-curable resin may include an organic monomer including an acrylate functional group. In addition, the light-curable resin may have a relatively low viscosity of, for example, about 10 cPS to about 500 cPS. Accordingly, the first lower protective film LPF1, the second lower protective film LPF2, and the upper protective film UPF may be smoothly formed by an inkjet printing process.

[0065] In some embodiments, the carbon nanocomposite material includes graphene oxide particles (GO), and may further include reduced graphene oxide particles (rGO), carbon black, non-graphene oxide, and / or carbon nanotubes (CNTs), and the like.

[0066] In some embodiments, the graphene oxide particles may have a size of about 0.1 μm to about 2 μm, and may have a plate-like structure. Preferably, the graphene oxide particles may have a size of about 0.3 μm. In addition, the weight ratio of the carbon nanocomposite may be about 0.05wt% to about 20wt%, and preferably, may be about 10wt%. By adjusting the size of the graphene oxide particles and the weight ratio of the carbon nanocomposite, the dispersibility of the carbon nanocomposite in the photocurable resin may be improved. However, the size of the graphene oxide particles and the weight ratio of the carbon nanocomposite are not limited to the above values, and may be appropriately adjusted as needed considering the diameter of the inkjet nozzle, the dispersibility of the carbon nanocomposite in the photocurable resin, etc.

[0067] Meanwhile, although it has been described that the first lower protection film LPF1, the second lower protection film LPF2, and the upper protection film UPF include the same material, the present invention is not limited thereto. For example, the upper protection film UPF may be implemented as a plastic film such as a PET film.

[0068] Figure 3 is to explain that manufacturing includes Figure 1 A flow chart of a method for providing a protective film in a display device. Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 It is an interpretation Figure 3 Graph of the method.

[0069] refer to Figure 3, a method (S1000) for manufacturing a protective film (e.g., a first lower protective film LPF1, a second lower protective film LPF2, and an upper protective film UPF) includes: preparing graphene oxide particles 100 in a powder state (S100), dispersing the graphene oxide particles 100 in water (S200), ultrasonically treating the graphene oxide particles 100 dispersed in water (S300), removing water from the ultrasonically treated graphene oxide particles 100 (S400), and mixing the graphene oxide particles 100 from which water has been removed with a polymer resin 200 (S500).

[0070] The display device DD (see Figure 1 ) may be manufactured by forming a display panel PNL on a flexible substrate SUB and forming a manufactured protection film on a lower surface of the flexible substrate SUB.

[0071] refer to Figure 3 and Figure 4 , graphene oxide particles 100 in a powdery state may be prepared (S100). For example, the graphene oxide particles 100 may have a size of about 20 μm to about 40 μm, and specifically, may have a size of about 30 μm.

[0072] refer to Figure 3 and Figure 5 , the graphene oxide particles 100 may be dispersed in water (S200). For example, the graphene oxide particles 100 dispersed in water may have a size of about 5 μm to about 15 μm, and specifically, may have a size of about 10 μm.

[0073] refer to Figure 3 and Figure 6 , the size of the graphene oxide particles 100 having the adjusted size may be about 0.1 μm to about 2 μm. In some embodiments, the size of the graphene oxide particles 100 may be adjusted by ultrasonic treatment of the graphene oxide particles 100 (S300). For example, in the case where the graphene oxide particles 100 are dispersed in water, a water bath ultrasonic treatment process may be performed for about 1 hour, and a tip ultrasonic treatment process may be performed for about 1 hour. In another example, a tip ultrasonic treatment process may be performed on the graphene oxide particles 100 dispersed in water for about 2 hours.

[0074] However, the method of adjusting the size of the graphene oxide particles 100 is not limited to what is explicitly described herein, and various physical / chemical processes can be applied to achieve the desired size of the graphene oxide particles 100 .

[0075] refer to Figure 3 and Figure 7, water may be removed from the graphene oxide particles 100 after the size adjustment (S400). In some embodiments, water may be removed from the graphene oxide particles 100 by a freeze-drying process.

[0076] Subsequently, a composite ink for a protective film can be manufactured by mixing the dried graphene oxide particles 100 from which water has been removed with the polymer resin 200 (S500). For example, the graphene oxide particles 100 and the polymer resin 200 can be mixed by a mixing process such as ultrasonic treatment, stirring or grinding. In this case, water has been removed from the graphene oxide particles 100, which improves the dispersibility of the graphene oxide particles 100 in the polymer resin 200.

[0077] Figure 8 It is shown that the Young's modulus value of the sample (freeze-dried GO) using the graphene oxide particles 100 whose size is adjusted to about 0.1 μm to about 2 μm is increased compared to the Young's modulus value of the sample (GO powder) using the graphene oxide particles prepared to have a size of about 30 μm. In other words, by appropriately adjusting the size of the graphene oxide particles 100, the strength of the protective film can be improved.

[0078] In addition, by using the protective film mixed with the carbon nanocomposite material and the polymer resin 200, the heat dissipation function of the protective film may be improved compared to the existing PET film (ie, PET protective film).

[0079] Figures 9 to 22 is to explain the application of Figure 3 FIG. 1 is a diagram of an example of a method for manufacturing a protective film. Fig. 9 and Fig.10 is a diagram illustrating an example of a method of manufacturing a protective film. Fig.11 is a diagram illustrating another example of the method of manufacturing the protective film. Fig.12 is a diagram illustrating still another example of the method of manufacturing the protective film. Fig.13 and Fig.14 is a diagram illustrating still another example of the method of manufacturing the protective film. Fig.15 and Fig.16 is a diagram illustrating still another example of the method of manufacturing the protective film.

[0080] Fig.17 and Fig.18 is a diagram illustrating still another example of the method of manufacturing the protective film. Fig.19 and Fig. 20 is a diagram illustrating still another example of the method of manufacturing the protective film. Fig.21 is a diagram illustrating still another example of the method of manufacturing the protective film. Fig. 22 is a diagram illustrating still another example of the method of manufacturing the protective film.

[0081] refer to Fig. 9 and Fig.10 ,like Fig. 9 As shown in , the flexible substrate SUB, the display panel PNL, the sensing layer SL and the upper protection film UPF may be stacked in sequence and then turned upside down. Fig.10 As shown in , the first lower protective film LPF1 and the second lower protective film LPF2 may be formed by an inkjet printing process using an inkjet head HD and a light irradiator LI. The inkjet head HD may discharge the above-mentioned composite ink 300, and the light irradiator LI may irradiate UV. The composite ink 300 may be cured by UV and may be implemented in the form of a film.

[0082] Since the protective film is formed by the inkjet printing process, the protective film may be formed in a desired region. For example, the first lower protective film LPF1 and the second lower protective film LPF2 may be formed only in the flat region FA, but not in the bending region BA.

[0083] refer to Fig. 9 and Fig.11 , a protective film having a stacked structure may be formed using the first composite ink 310 and the second composite ink 320 having different physical properties. For example, a first inkjet head HD1 for discharging the first composite ink 310, a first light irradiator LI1 for curing the first composite ink 310, a second inkjet head HD2 for discharging the second composite ink 320, and a second light irradiator LI2 for curing the second composite ink 320 may be used. In this case, after forming the first lower protective film LPF1 and the second lower protective film LPF2 including the second composite ink 320, an additional lower protective film A_LPF including the first composite ink 310 may be formed to overlap the first lower protective film LPF1.

[0084] refer to Fig. 9 and Fig.12 , protective films may be formed in two flat areas FA of the flexible substrate SUB using first composite ink 310 and second composite ink 320 having different physical properties, respectively. For example, a first inkjet head HD1 that discharges the first composite ink 310, a second inkjet head HD2 that discharges the second composite ink 320, and a light irradiator LI for curing the first composite ink 310 and the second composite ink 320 may be used. In this case, a first lower protective film LPF1 including the first composite ink 310 may be formed in the flat area FA adjacent to one side of the bending area BA, and a second lower protective film LPF2 including the second composite ink 320 may be formed in the flat area FA adjacent to the other side of the bending area BA.

[0085] refer to Fig.13 and Fig.14 ,like Fig.13As shown in FIG. , the display device DD (see Figure 1 ) may further include a glass substrate GLS having an etched portion. In this case, in order to prevent over-etching, an etching stop layer EST may be formed. Subsequently, as Fig.14 As shown in , the first lower protection film LPF1 and the second lower protection film LPF2 may be formed on the glass substrate GLS using the above-described inkjet printing process.

[0086] refer to Fig.15 and Fig.16 ,like Fig.15 As shown in , a glass substrate GLS used as a carrier substrate may be provided. In the manufacturing process of the display device, the glass substrate GLS may be removed by laser lift-off or chemical lift-off. Fig.16 As shown in FIG. 8 , the first lower protection film LPF1 and the second lower protection film LPF2 may be formed using an inkjet printing process.

[0087] refer to Fig.17 and Fig.18 ,like Fig.17 As shown in , the display device may further include a glass substrate GLS having an etched portion. In this case, similar to Fig.13 In the embodiment shown in FIG. 1 , an etching stop layer EST may be formed to prevent over-etching. Fig.18 As shown in , a cushion layer CUS may be formed. In detail, a cushion layer CUS may be formed on the first lower protective film LPF1 and the second lower protective film LPF2, and an additional lower protective film A_LPF may be formed on the cushion layer CUS. The first lower protective film LPF1, the second lower protective film LPF2, and the additional lower protective film A_LPF may perform a heat dissipation function, and the cushion layer CUS may perform a buffering function.

[0088] refer to Fig.19 and Fig. 20 ,like Fig.19 As shown in Fig.15 , a glass substrate GLS used as a carrier substrate may be provided. In the manufacturing process of the display device, the glass substrate GLS may be removed by laser lift-off or chemical lift-off. Fig. 20 As shown in FIG. 1 , first and second lower protective films LPF1 and LPF2 , an underlayer CUS, and an additional lower protective film A_LPF may be formed.

[0089] refer to Fig.21 In an embodiment, a plurality of glass patterns GLP may be formed on the lower surface of the flexible substrate SUB. For example, the plurality of glass patterns GLP may be formed throughout the entire area of ​​the display device. The lower protection film LPF may be formed to cover the plurality of glass patterns GLP and fill gaps between the plurality of glass patterns GLP.

[0090] refer to Fig. 22 In an embodiment, a plurality of glass patterns GLP may be formed on the lower surface of the flexible substrate SUB. For example, the plurality of glass patterns GLP may be formed in the bending area BA (see FIG. Figure 1 The lower protection film LPF may be formed to cover the plurality of glass patterns GLP and fill gaps between the plurality of glass patterns GLP.

[0091] The protective film according to an embodiment of the present invention may include a polymer resin and graphene oxide particles whose particle size is adjusted to a preselected range. Since the protective film includes both organic and inorganic materials, the heat dissipation function of the protective film can be improved, and the Young's modulus value can be increased, thereby improving the strength of the protective film.

[0092] In addition, the protective film can be formed by an inkjet printing process using a composite ink. Figures 9 to 22 As described above, protective films of various structures can be appropriately formed.

[0093] Although certain embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concept is not limited to these embodiments, but to the broader scope of the claims and to various obvious modifications and equivalent arrangements apparent to those of ordinary skill in the art.

Claims

1. A protective film, comprising: Light-curing resin; as well as A carbon nanocomposite material comprising graphene oxide particles, wherein the size of the graphene oxide particles is adjusted to achieve a preselected dispersibility in the carbon nanocomposite material.

2. The protective film according to claim 1, wherein: The size of the graphene oxide particles is 0.1 μm to 2 μm.

3. The protective film according to claim 1, wherein: The weight ratio of the carbon nanocomposite material is 0.05 wt % to 20 wt % based on the total weight of the photocurable resin.

4. The protective film according to claim 1, wherein The carbon nanocomposite material further includes carbon black.

5. The protective film according to claim 1, wherein The photocurable resin is cured by light and has a viscosity of 10 cPS to 500 cPS.

6. A display device, comprising: A lower protective film, comprising a photocurable resin and a carbon nanocomposite material, wherein the carbon nanocomposite material comprises graphene oxide particles; A flexible substrate, disposed on the lower protective film; A transistor layer is disposed on the flexible substrate; and The emission layer is arranged on the transistor layer.

7. The display device according to claim 6, wherein: The size of the graphene oxide particles is 0.1 μm to 2 μm.

8. The display device according to claim 6, wherein: The flexible substrate comprises: a flat region having a first flat region and a second flat region; and a bending area between the first flat area and the second flat area, Wherein, the lower protective film overlaps with the flat area and does not overlap with the bent area.

9. The display device according to claim 6, further comprising: A plurality of glass patterns are arranged below the flexible substrate, Wherein, the lower protective film covers the plurality of glass patterns.

10. A method for manufacturing a display device, the method comprising: Forming a protective film; forming a display panel on a flexible substrate; as well as forming the protective film below the flexible substrate, Wherein, forming the protective film comprises: preparing graphene oxide particles in a powder state; adjusting the size of the graphene oxide particles; and A composite ink is formed by mixing the graphene oxide particles having an adjusted size with a photocurable resin.

11. The method according to claim 10, wherein: The size of the graphene oxide particles having the adjusted size is 0.1 μm to 2 μm.

12. The method according to claim 10, wherein: The size of the graphene oxide particles in the powder state is 20 μm to 40 μm.

13. The method according to claim 10, further comprising: The graphene oxide particles in a powder state are dispersed in water.

14. The method according to claim 13, wherein: The size of the graphene oxide particles dispersed in water is 5 μm to 15 μm.

15. The method according to claim 10, wherein: The size of the graphene oxide particles is adjusted by ultrasonic treatment of the graphene oxide particles.

16. The method according to claim 10, further comprising: Water is removed from the graphene oxide particles having the adjusted size.

17. The method according to claim 10, wherein: The protective film includes a first lower protective film and a second lower protective film having different physical properties from each other, wherein the first lower protective film is formed by ejecting a first composite ink from a first inkjet head, and The second lower protective film is formed by ejecting a second composite ink having physical properties different from those of the first composite ink from a second inkjet head.

18. The method according to claim 17, wherein: The first lower protective film and the second lower protective film overlap each other when the flexible substrate is in a bent state.

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