Cover window protective film and display apparatus including the same

Abstract

A cover window protective film and a display device including the same are disclosed, the cover window protective film including a base layer and a first protective layer disposed on the base layer, wherein the first protective layer includes a lower surface adjacent to the base layer and an upper surface opposite the lower surface, and the first protective layer includes a fluorine-based compound and has an atomic ratio of fluorine (F) gradually increasing from the lower surface toward the upper surface.

Description

Technical Field

[0001] This disclosure relates to cover window protective films and display devices including cover window protective films, and more specifically, to foldable display devices including cover window protective films. Background Technology

[0002] Electronic devices that provide images to users, such as smartphones, tablet PCs (“PCs”), digital cameras, laptops / notebook computers, navigators, and smart TVs, typically include display devices for displaying images.

[0003] Foldable display devices have recently garnered considerable attention. They can combine the desirable features of both smartphones and tablet PCs, such as portability and a wide screen. Summary of the Invention

[0004] The folding operation of a foldable display device can apply stress to each layer that makes up the display device. When some layers are exposed to such stress due to repeated folding and unfolding, defects such as cracks may occur.

[0005] Embodiments of this disclosure provide a cover window protective film with improved abrasion and chemical resistance to prevent fingerprint contamination of the cover window even during repeated use, and a display device including the cover window protective film.

[0006] According to an embodiment of the present disclosure, the cover window protective film includes a base layer and a first protective layer disposed on the base layer, wherein the first protective layer includes a lower surface adjacent to the base layer and an upper surface opposite to the lower surface, and the first protective layer includes a fluorine-based compound and has an atomic ratio of fluorine (F) that gradually increases from the lower surface to the upper surface.

[0007] In this embodiment, the atomic ratio of fluorine (F) can be highest at the upper surface of the first protective layer.

[0008] In one embodiment, the atomic ratio of fluorine (F) at the upper surface of the first protective layer can be in the range of about 10 atomic percentages (at%) to about 40 at%.

[0009] In an embodiment, the first protective layer may further include carbon (C), and at the upper surface of the first protective layer, the ratio of the atomic ratio of fluorine (F) to the atomic ratio of carbon (C) may be in the range of about 0.15 to about 1.20.

[0010] In an implementation, the atomic ratio of fluorine (F) and the atomic ratio of carbon (C) can be values ​​measured by an X-ray photoelectron spectroscopy instrument.

[0011] In one embodiment, the upper surface of the first protective layer may have a modulus in the range of about 4.5 gigapascals (GPa) to about 10 GPa.

[0012] In one embodiment, the upper surface of the first protective layer may have a hardness in the range of about 0.35 GPa to about 1.00 GPa.

[0013] In this implementation, the modulus and hardness can be values ​​measured using a nanoindenter.

[0014] In an implementation, the first protective layer may have a thickness ranging from about 2 micrometers (μm) to about 7 μm.

[0015] In an embodiment, the cover window protective film may further include a second protective layer disposed on the upper surface of the first protective layer, wherein the upper surface of the second protective layer may have a modulus in the range of about 4.5 GPa to about 10 GPa and a hardness in the range of about 0.35 GPa to about 1.00 GPa.

[0016] According to an embodiment of this disclosure, a display device includes a display panel and a front laminate structure disposed on the front surface of the display panel. The front laminate structure includes a cover window and a cover window protective film attached to the cover window. The cover window protective film includes a base layer and a first protective layer disposed on the base layer. The first protective layer includes a fluorine-based compound. In such an embodiment, the first protective layer includes a lower surface adjacent to the base layer and an upper surface opposite to the lower surface, and the first protective layer has a higher atomic ratio of fluorine (F) at its upper surface than at its lower surface.

[0017] In an embodiment, the front stack structure may further include a polarizing member disposed between the display panel and the cover window, and a polarizing member connecting member for attaching the polarizing member to a surface of the display panel.

[0018] In an embodiment, the front stack structure may further include an impact absorption layer disposed between the polarizing member and the cover window, and an impact absorption layer connecting member for attaching the impact absorption layer to the polarizing member.

[0019] In an embodiment, the display panel may further include a back stack structure disposed on the back surface of the display panel, and the back stack structure may include a polymer film layer disposed on the rear side of the display panel, a pad layer disposed on the rear side of the polymer film layer, a plate disposed on the rear side of the pad layer, and a heat dissipation member disposed on the rear side of the plate.

[0020] In one embodiment, the atomic ratio of fluorine (F) at the upper surface of the first protective layer can be in the range of about 10 at% to about 40 at%. The first protective layer also includes carbon (C). At the upper surface of the first protective layer, the ratio of the atomic ratio of fluorine (F) to the atomic ratio of carbon (C) can be in the range of about 0.15 to about 1.20. The atomic ratio of fluorine (F) and the atomic ratio of carbon (C) can be values ​​measured by X-ray photoelectron spectroscopy.

[0021] In one embodiment, the upper surface of the first protective layer may have a modulus in the range of about 4.5 GPa to about 10 GPa, and the upper surface of the first protective layer may have a hardness in the range of about 0.35 GPa to about 1.00 GPa, and the modulus and hardness may be values ​​measured by a nanoindenter.

[0022] In an implementation, the first protective layer may have a thickness in the range of about 2 μm to about 7 μm.

[0023] In an embodiment, the display device may further include a second protective layer disposed on the upper surface of the first protective layer, wherein the upper surface of the second protective layer may have a modulus in the range of about 4.5 GPa to about 10 GPa and a hardness in the range of about 0.35 GPa to about 1.00 GPa.

[0024] In one implementation, the display panel displays the image in a forward direction.

[0025] In an embodiment, the display device may be an inwardly foldable display device in which the display surface is folded inward, or an outwardly foldable display device in which the display surface is folded outward. Attached Figure Description

[0026] The above and other features of this disclosure will become more apparent from the detailed description of embodiments thereof with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a perspective view showing a display device in an unfolded state according to an embodiment;

[0028] Figure 2 This is a perspective view showing a display device in a folded state according to an embodiment;

[0029] Figure 3 This is a cross-sectional view of a display device in an unfolded state according to an embodiment;

[0030] Figure 4 This is a cross-sectional view of a display device in a folded state according to an embodiment;

[0031] Figure 5 This is a cross-sectional view of the display panel according to the embodiment;

[0032] Figure 6 This is a schematic cross-sectional view of the protective film covering the window according to the embodiment;

[0033] Figure 7 This is a schematic diagram illustrating an embodiment of the process for manufacturing a protective film for window covers;

[0034] Figure 8 This is a schematic cross-sectional view of the cover window protective film according to an optional embodiment;

[0035] Figure 9 This is a cross-sectional view of the display panel according to an alternative implementation.

[0036] Figure 10 This is a cross-sectional view of the display panel according to another alternative embodiment;

[0037] Figure 11 This is a graph showing the composition of sample #1 relative to etching time;

[0038] Figure 12 This is a graph showing the composition of sample #2 relative to etching time;

[0039] Figure 13 This is a graph showing the composition of sample #3 relative to etching time;

[0040] Figure 14 This is a cross-sectional view illustrating an embodiment of a method for measuring the modulus and hardness of the first protective layer using an indenter;

[0041] Figure 15 It is a graph showing the relationship between indentation depth and load;

[0042] Figure 16 It is a graph showing the relationship between the indentation depth of the first protective layer and the load according to Experimental Example 1;

[0043] Figure 17 It is a graph showing the relationship between wear resistance and modulus, [F] / [C] component ratio, and hardness; and

[0044] Figure 18 It is a graph showing the relationship between chemical resistance and modulus, [F] / [C] component ratio and hardness. Detailed Implementation

[0045] The invention will now be described more fully below with reference to the accompanying drawings, in which various embodiments of the invention are illustrated. However, the invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The same reference numerals throughout denote the same elements.

[0046] It should also be understood that when a layer is referred to as being "on" another layer or substrate, it may be directly on that other layer or substrate, or there may be an intervening layer between them. Conversely, when an element is referred to as being "directly on another element," there is no intervening element.

[0047] It should be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Therefore, without departing from the teachings herein, “first element,” “first component,” “first region,” “first layer,” or “first part” discussed below may be referred to as a second element, second component, second region, second layer, or second part.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, “a,” “an,” “the,” and “at least one” do not indicate a limitation of quantity and are intended to include both the singular and the plural unless the context clearly indicates otherwise. For example, “an element” has the same meaning as “at least one element” unless the context clearly indicates otherwise. “At least one” should not be construed as limiting “a” or “an.” “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used in this specification, the terms “comprises” and / or “comprising” or “includes” and / or “including” specify the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or groups thereof.

[0049] Furthermore, relative terms such as “below” or “bottom” and “above” or “top” may be used herein to describe the relationship between one element and another, as shown in the accompanying drawings. It should be understood that, in addition to the orientation depicted in the drawings, the relative terms are intended to also include different orientations of the device. For example, if the device in one of the drawings is flipped, an element described as being “below” the other elements will be oriented “above” the other elements. Thus, the term “below” can include both “below” and “above” orientations, depending on the specific orientation of the drawing. Similarly, if the device in one of the drawings is flipped, an element described as being “below” or “under” the other elements will be oriented “above” the other elements. Thus, the term “below” or “under” can include both “above” and “below” orientations.

[0050] As used herein, “about” or “approximately” includes the stated value and means within an acceptable range of deviation from the particular value as determined by a person 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., limitations of the measurement system). For example, “about” may mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, or ±5%.

[0051] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should also be understood that terms such as those defined in common dictionaries shall be interpreted as having the same meaning as they have in the context of the relevant technology and this disclosure, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0052] Embodiments are described herein with reference to cross-sectional views as schematic illustrations of idealized embodiments. Thus, variations in the shapes of the illustrations due to, for example, manufacturing techniques and / or tolerances are to be expected. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but should include deviations in shape due to, for example, manufacturing processes. For example, regions shown or described as flat may generally have rough and / or non-linear features. Furthermore, sharp corners shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the precise shapes of the regions, nor are they intended to limit the scope of the present claims.

[0053] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0054] Figure 1 This is a perspective view showing a display device in an unfolded state according to an embodiment, and Figure 2This is a perspective view showing a display device in a folded state according to an embodiment.

[0055] refer to Figure 1 The display device 10 can be implemented as a foldable display device. In the following description, for ease of description, the display device 10 will be described in detail as an implementation of a smartphone, but this disclosure is not limited thereto. In such an implementation, in addition to smartphones, the display device 10 can also be applied to portable phones, tablet PCs (“PCs”), personal digital assistants (“PDAs”), portable multimedia players (“PMPs”), televisions, game consoles, wristwatch-type electronic devices, head-mounted displays, monitors for personal computers, laptop computers, vehicle navigation systems, vehicle dashboards, digital cameras, camcorders, billboards, medical devices, examination equipment, various home appliances (such as refrigerators and washing machines), and Internet of Things (IoT) devices.

[0056] exist Figure 1 and Figure 2 In this context, the first direction DR1 can be a direction parallel to one side of the display device 10 when viewed in a plane, for example, it can be the vertical direction or the length direction of the display device 10. The second direction DR2 can be a direction parallel to the other side of the display device 10 (the side that contacts the display device 10) when viewed in a plane, for example, it can be the horizontal direction or the width direction of the display device 10. The third direction DR3 can be the thickness direction of the display device 10.

[0057] In this embodiment, the display device 10 may have a rectangular shape when viewed on a plane or in a plan view on a third direction DR3. When viewed on a plane, the display device 10 may have a rectangular shape with right angles at the corners, or a rectangular shape with rounded corners. When viewed on a plane, the display device 10 may include two short sides arranged in the first direction DR1 and two long sides arranged in the second direction DR2.

[0058] Display device 10 may include a display area DA and a non-display area NDA. When viewed on a plane, the shape of the display area DA may correspond to the shape of display device 10. In one embodiment, for example, if display device 10 has a rectangular shape when viewed on a plane, the display area DA may also have a rectangular shape.

[0059] The display area DA can be an area with multiple pixels for displaying an image. The multiple pixels can be arranged in a matrix. In one implementation, each of the multiple pixels can have a rectangular, rhomboid, or square shape when viewed on a plane, but its shape is not limited to these. In an alternative implementation, for example, each of the multiple pixels can have a polygonal, circular, or elliptical shape when viewed on a plane.

[0060] The non-display area NDA can be a region with no pixels, so that no image is displayed within it. The non-display area NDA can be positioned around the display area DA. In implementations, such as... Figure 1 As shown, the non-display area NDA can be configured to surround the display area DA, but this disclosure is not limited thereto. In an alternative embodiment, the display area DA can be partially surrounded by the non-display area NDA.

[0061] In one embodiment, the display device 10 can be held in both a folded state and an unfolded state. In another embodiment, such as... Figure 2 As shown, the display device 10 can be folded in an inward folding manner, in which the display area DA is disposed inside. When the display device 10 is folded in an inward folding manner, the upper surfaces of the display device 10 can be arranged to face each other. In an embodiment, the display device 10 can be folded in an outward folding manner, in which the display area DA is disposed outside. When the display device 10 is folded in an outward folding manner, the lower surfaces of the display device 10 can be arranged to face each other.

[0062] In this embodiment, the display device 10 may be a foldable device. As used herein, a foldable device is a device capable of being folded, and refers to a device capable of being in both a folded and unfolded state, as well as a folding device. Furthermore, folding generally refers to the display device 10 folding at an angle of approximately 180°, but this disclosure is not limited thereto, and may also refer to the display device 10 folding at an angle greater than or less than 180°, or folding at an angle of 90° or greater and less than 180°, or folding at an angle of 120° or greater and less than 180°. Furthermore, the folded state may be referred to as the folded state when the display device 10 is folded outward from the unfolded state, even if a complete fold is not performed. Even if the display device 10 folds at an angle of 90° or less, as long as the maximum folding angle is, for example, 90° or greater, it can be indicated that the display device 10 is in a folded state to distinguish it from the unfolded state. The radius of curvature during folding may be approximately 5 millimeters (mm) or less, for example, in the range of approximately 1 mm to approximately 2 mm, or approximately 1.5 mm, but is not limited thereto.

[0063] In one embodiment, the display device 10 may include a folded region FDA, a first non-folded region NFA1, and a second non-folded region NFA2. The folded region FDA is the area of ​​the display device 10 that is folded. The first non-folded region NFA1 and the second non-folded region NFA2 may be areas of the display device 10 that are not folded.

[0064] The first non-folded region NFA1 can be located on one side of the folded region FDA, for example, on the upper side of the folded region FDA. The second non-folded region NFA2 can be located on the other side of the folded region FDA, for example, on the lower side of the folded region FDA. The folded region FDA can be a region curved with a predetermined curvature.

[0065] In one embodiment, the folded area FDA of the display device 10 can be defined at a specific location. In the display device 10, a single folded area FDA or two or more folded areas FDA can be defined at a specific location. In an alternative embodiment, the location of the folded area FDA is not specified in the display device 10 and can be freely set in various areas.

[0066] In this embodiment, the display device 10 can be folded along the second direction DR2. Therefore, the length of the display device 10 along the second direction DR2 can be reduced to approximately half, allowing the user to easily carry the display device 10.

[0067] In this embodiment, the folding direction of the display device 10 is not limited to the second direction DR2. In an alternative embodiment, for example, when the display device 10 is folded in the first direction DR1, the length of the display device 10 in the first direction DR1 can be reduced to approximately half.

[0068] In the implementation method, such as Figure 1 and Figure 2 As shown, each of the display area DA and the non-display area NDA overlaps with the folded area FDA, the first non-folded area NFA1, and the second non-folded area NFA2, but this disclosure is not limited thereto. In one embodiment, for example, each of the display area DA and the non-display area NDA may overlap with at least one selected from the folded area FDA, the first non-folded area NFA1, and the second non-folded area NFA2.

[0069] Figure 3 This is a cross-sectional view of a display device in an unfolded state according to an embodiment, and Figure 4 This is a cross-sectional view of a display device in a folded state according to an embodiment.

[0070] refer to Figure 3 and Figure 4An embodiment of the display device 10 may include a display panel 100, a front stacked structure 200 stacked on the front side of the display panel 100, and a back stacked structure 300 stacked on the rear side of the display panel 100. Each of the stacked structures 200 and 300 may include at least one connecting member 251 to 254 and 351 to 354. Here, the front side of the display panel 100 refers to the direction in which the display panel 100 displays a screen, and the rear side of the display panel 100 refers to the direction opposite to the front side of the display panel 100. One surface of the display panel 100 is positioned on the front side of the display panel 100, and the other surface of the display panel 100 is positioned on the rear side of the display panel 100.

[0071] Display panel 100 is a panel used to define a screen or display an image, and may include: self-emissive display panels, such as organic light-emitting display panels (“OLED”), inorganic light-emitting (inorganic “EL”) display panels, quantum dot light-emitting display panels (“QED”), micron-sized light-emitting diode (micron “LED”) display panels, nano-LED display panels, plasma display panels (“PDP”), field emission display (“FED”) panels, and cathode ray tube (“CRT”) display panels; and light-receiving display panels, such as liquid crystal display (“LCD”) panels and electrophoretic display (“EPD”) panels. In the following description, for ease of description, display panel 100 will be described in detail as an embodiment of an organic light-emitting display panel, and unless otherwise stated, the organic light-emitting display panel applied to the embodiments will be simply referred to as a display panel. However, the embodiments are not limited to organic light-emitting display panels, and other types of display panels listed above or known in the art may be applied within the teachings herein.

[0072] The display panel 100 may also include a touch component. The touch component may be provided as a separate panel or film from the display panel 100 and attached to the display panel 100, or it may be provided as a touch layer inside the display panel 100. In embodiments, the touch component is disposed inside the display panel 100, and it is shown that the touch component is included in the display panel 100, but this is not a limitation.

[0073] Figure 5 This is a cross-sectional view of the display panel according to the embodiment.

[0074] refer to Figure 5 An embodiment of the display device 10 may include a display panel 100. The display panel 100 may include a display layer 30 and a touch sensor 40 on the display layer 30. In such an embodiment, the display layer 30 may include a base substrate 11, a first electrode 12, a pixel defining layer 13, a light-emitting layer 14, a second electrode 15, and an encapsulation layer 20.

[0075] The base substrate 11 may be an insulating substrate. In embodiments, the base substrate 11 may be flexible and may comprise a flexible polymer material. In such embodiments, the polymer material may include polyimide (“PI”), polyethersulfone (“PES”), polyacrylate (“PA”), polyarylate (“PAR”), polyetherimide (“PEI”), polyethylene naphthalate (“PEN”), polyethylene terephthalate (“PET”), polyphenylene sulfide (“PPS”), polyallyl ester, polycarbonate (“PC”), cellulose triacetate (“CAT”), cellulose acetate propionate (“CAP”), or combinations thereof.

[0076] The first electrode 12 may be disposed on the base substrate 11. In one embodiment, the first electrode 12 may be a positive electrode. In another embodiment, multiple components (not shown) may also be disposed between the base substrate 11 and the first electrode 12. In such an embodiment, the multiple components may include, for example, a buffer layer, multiple conductive wirings, an insulating layer, and multiple thin-film transistors.

[0077] A pixel defining layer 13 may be disposed on the first electrode 12. In such an embodiment, the pixel defining layer 13 defines an opening that exposes at least a portion of the first electrode 12.

[0078] The light-emitting layer 14 may be disposed on the first electrode 12. In an embodiment, the light-emitting layer 14 may emit one of red, green, and blue light. The wavelength of the red light may be in the range of about 620 nanometers (nm) to about 750 nm, the wavelength of the green light may be in the range of about 495 nm to about 570 nm, and the wavelength of the blue light may be in the range of about 450 nm to about 495 nm. The light-emitting layer 14 may be formed as a single layer. Optionally, the light-emitting layer 14 may have a structure in which multiple organic light-emitting layers are stacked on top of each other, for example, in a series structure. In another optional embodiment, the light-emitting layer 14 may emit white light. In the embodiment where the light-emitting layer 14 emits white light, the light-emitting layer 14 may have a structure in which a red organic light-emitting layer, a green organic light-emitting layer, and a blue organic light-emitting layer are stacked on top of each other.

[0079] The second electrode 15 can be disposed on the light-emitting layer 14 and the pixel defining layer 13. In an embodiment, the second electrode 15 can be completely formed on the light-emitting layer 14 and the pixel defining layer 13. In an embodiment, the second electrode 15 can be a cathode electrode.

[0080] The first electrode 12, the second electrode 15, and the light-emitting layer 14 can constitute a light-emitting element EL.

[0081] The encapsulation layer 20 can be disposed on the light-emitting element EL. The encapsulation layer 20 can encapsulate the light-emitting element EL and prevent moisture and other substances from flowing into the light-emitting element EL from the outside.

[0082] In one embodiment, the encapsulation layer 20 can be implemented as a thin-film encapsulation and may include one or more organic films and one or more inorganic films. In one embodiment, for example, the encapsulation layer 20 includes a first inorganic film 21 disposed on the second electrode 15, an organic film 22 disposed on the first inorganic film 21, and a second inorganic film 23 disposed on the organic film 22.

[0083] The first inorganic film 21 can prevent moisture, oxygen, etc. from penetrating into the light-emitting element EL. The first inorganic film 21 may include at least one material selected from silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, and silicon oxide nitride (SiON), or may be made of at least one material selected from silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, and silicon oxide nitride (SiON).

[0084] An organic film 22 may be disposed on the first inorganic film 21. The organic film 22 may improve flatness or provide a flat surface on the underlying layer. The organic film 22 may comprise or be formed from a liquid organic material, and may include, for example, at least one material selected from acrylic resins, methacrylic resins, polyisoprene, vinyl resins, epoxy resins, polyurethane resins, cellulose resins, and dinaphthalene-containing resins. Such organic materials may be deposited, printed, and coated onto the base substrate 11, and may undergo a curing process to form the organic film 22.

[0085] The second inorganic film 23 can be disposed on the organic film 22. The second inorganic film 23 can perform a function substantially the same as or similar to that of the first inorganic film 21, and can comprise or be formed of a material substantially the same as or similar to that of the first inorganic film 21. The second inorganic film 23 can completely cover the organic film 22. In an embodiment, the second inorganic film 23 and the first inorganic film 21 can contact each other in the non-display area NDA to form an inorganic-inorganic junction. However, the structure of the encapsulation layer 20 is not limited to this, and the stacked structure of the encapsulation layer 20 can be changed or modified in various ways. Optionally, the encapsulation layer 20 can be formed as a glass substrate, etc.

[0086] The touch sensor 40 can be disposed on the encapsulation layer 20. In one embodiment, the touch sensor 40 can be directly disposed on the encapsulation layer 20. In such an embodiment, the encapsulation layer 20 can serve as the base part of the touch sensor 40.

[0087] The touch sensor 40 may include a touch element layer 41 and a protective layer 43. The touch element layer 41 may include touch electrodes and touch signal lines connected to the touch electrodes. In one embodiment, the touch electrodes may include metal and may have a mesh shape. In such an embodiment, the touch electrodes may include, or be formed of, a metal mesh pattern, and thus the flexibility of the touch element layer 41 may be improved.

[0088] A protective layer 43 may be disposed on the touch element layer 41 and may protect the touch element layer 41. In embodiments, the protective layer 43 may comprise an organic material, and may comprise, for example, an acrylic polymer, or be made of, for example, an acrylic polymer. In such embodiments where the protective layer 43 is made of an organic material, the flexibility of the touch sensor 40 may be improved.

[0089] Return to reference Figure 3 and Figure 4 The front stack structure 200 can be disposed on the front side of the display panel 100. The front stack structure 200 may include a polarizing member 240, an impact absorption layer 230, a cover window 220 and a cover window protective film 210 stacked sequentially from the display panel 100 forward.

[0090] Polarizing member 240 polarizes transmitted light. Polarizing member 240 can be used to reduce reflection of external light. In an embodiment, polarizing member 240 may be a polarizing film. The polarizing film may include a polarizing layer and a protective substrate sandwiching the polarizing layer from the top and bottom of the polarizing layer. The polarizing layer may include polyvinyl alcohol. The polarizing layer may be stretched in one direction. The stretching direction of the polarizing layer may be the absorption axis, and the direction perpendicular to it may be the transmission axis. The protective substrate may be disposed on one surface and another surface of the polarizing layer. The protective substrate may include a cellulose resin (such as TAC, polyester resin, etc.), or be made of a cellulose resin (such as TAC, polyester resin, etc.), but its material is not limited thereto.

[0091] The shock-absorbing layer 230 may be disposed on the front side of the polarizing member 240. The shock-absorbing layer 230 may be used to protect structures such as the display panel 100 beneath it from external impacts. In an embodiment, the shock-absorbing layer 230 may be a polymer film. The polymer film may include at least one material selected from PET, PEN, PES, PI, PAR, PC, polymethyl methacrylate (“PMMA”), and cyclic olefin copolymers (“COC”).

[0092] Cover window 220 may be disposed on the front side of impact-absorbing layer 230. Cover window 220 is used to protect display panel 100. Cover window 220 may include, or be made of, a transparent material. Cover window 220 may include, for example, glass or plastic, or be made of, for example, glass or plastic.

[0093] In embodiments where the cover window 220 includes glass, the glass may be ultrathin glass (“UTG”) or thin glass. In embodiments where the glass is formed as a thin film or ultrathin film, the cover window 220 has flexible properties and can therefore be warped, bent, folded, or rolled. The thickness of the glass may, for example, range from about 10 micrometers (μm) to about 300 μm, and specifically, glass with a thickness in the range of about 10 μm to about 100 μm (e.g., about 30 μm) may be applied. The glass of the cover window 220 may include soda-lime glass, alkaline aluminosilicate glass, borosilicate glass, or lithium aluminosilicate glass. The glass of the cover window 220 may include chemically strengthened or thermally strengthened glass to have high strength. Chemical strengthening can be achieved by an ion exchange treatment process in an alkali metal salt. The ion exchange treatment process may be performed two or more times. In embodiments, the cover window 220 may be formed by coating both side surfaces of a polymer film with a glass film.

[0094] refer to Figure 3 and Figure 4 In embodiments where the cover window 220 comprises plastic, the cover window 220 may have flexible properties, such as folding. In such embodiments, the plastic included in the cover window 220 may be, but is not limited to, at least one material selected from PI, PA, PMMA, PC, PEN, polyvinylidene chloride, polyvinylidene fluoride (“PVDF”), polystyrene, ethylene-vinyl alcohol copolymer, PES, PEI, PPS, polyallyl ester, triacetyl cellulose (“TAC”), and CAP. The plastic cover window 220 may be formed from one or more of the plastic materials listed above.

[0095] A cover window protective film 210 may be disposed on the front side of the cover window 220. The cover window protective film 210 may perform at least one function selected from anti-scattering, shock absorption, impact resistance, fingerprint resistance, and anti-glare on the cover window 220. The cover window protective film 210 may include a transparent polymer film. The transparent polymer film may include at least one material selected from PET, PEN, PES, PI, PAR, PC, PMMA, and COC resins.

[0096] The cover window protective film 210 may include a base layer and a protective layer disposed on the base layer. The protective layer may have a high rigidity for protecting the cover window 220 and may have a modulus such that it does not deform when the display device 10 is repeatedly folded and unfolded. In such an embodiment, the protective layer may include or be made of a material containing specific components such that fingerprints are not retained on the surface when the user uses the display device 10. The cover window protective film 210 will be described in more detail later.

[0097] The front stack structure 200 may further include front connecting members 251 to 254 that connect adjacent stack members to each other. In one embodiment, for example, a first connecting member 251 may be disposed between the cover window 220 and the cover window protective film 210 to connect them to each other, a second connecting member 252 may be disposed between the cover window 220 and the shock-absorbing layer 230 to connect them to each other, a third connecting member 253 may be disposed between the shock-absorbing layer 230 and the polarizing member 240 to connect them to each other, and a fourth connecting member 254 may be disposed between the polarizing member 240 and the display panel 100 to connect them to each other. In such an embodiment, the front connecting members 251 to 254 are members that attach layers to a surface of the display panel 100. The first connecting member 251 may be a protective layer connecting member for attaching the cover window protective film 210, the second connecting member 252 may be a window connecting member for attaching the cover window 220, the third connecting member 253 may be an impact absorption layer connecting member for attaching the impact absorption layer 230, and the fourth connecting member 254 may be a polarization unit connecting member for attaching the polarization member 240. Each of the front connecting members 251 to 254 may be optically transparent.

[0098] The back stack structure 300 is disposed on the rear side of the display panel 100. The back stack structure 300 may include a polymer film layer 310, a pad layer 320, a plate 330 and a heat dissipation component 340 stacked sequentially from the display panel 100 to the rear.

[0099] The polymer film layer 310 may include a polymer film. The polymer film layer 310 may include at least one material selected from, for example, PI, PET, PC, polyethylene (“PE”), polypropylene (“PP”), polysulfone (“PSF”), PMMA, TAC, and cyclic olefin polymers (“COP”). The polymer film layer 310 may include a functional layer in at least one surface thereon. The functional layer may include, for example, a light-absorbing layer. The light-absorbing layer may include a light-absorbing material, such as a black pigment or dye. The light-absorbing layer may be formed on the polymer film by coating or printing with black ink.

[0100] A cushion layer 320 may be disposed behind the polymer film layer 310. The cushion layer 320 can absorb external impacts to prevent damage to the display panel 100. The cushion layer 320 may be formed as a single layer or multiple stacked layers. The cushion layer 320 may include, for example, an elastic material, such as polyurethane resin or polyethylene resin. In embodiments, the cushion layer 320 may include, or be made of, a foam material similar to a sponge.

[0101] Plate 330 may be disposed on the rear side of pad 320. Plate 330 may be a support member for attaching display device 10 to housing. Plate 330 may include a rigid material. In embodiments, plate 330 may include metal or metal alloy (such as stainless steel (“SUS”)), or be made of metal or metal alloy (such as stainless steel (“SUS”)).

[0102] A heat dissipation component 340 may be disposed on the rear side of the plate 330. The heat dissipation component 340 is used to dissipate heat generated from the display panel 100 or other components of the display device 10. The heat dissipation component 340 may include a metal plate. The metal plate may include, for example, a metal with high thermal conductivity, such as copper or silver. The heat dissipation component 340 may be a heat sink comprising graphite or carbon nanotubes.

[0103] The heat dissipation component 340 can be separated based on the folded area FDA to facilitate the display device 10, such as Figure 2 and Figure 4 The folding is performed as shown in the diagram. However, this disclosure is not limited thereto. In an alternative embodiment, for example, a first metal plate may be disposed in a first non-folded region NFA1, and a second metal plate may be disposed in a second non-folded region NFA2. The first and second metal plates may be physically spaced apart from each other based on the folded region FDA.

[0104] The back-mounted structure 300 may further include back-mounted connecting members 351 to 354 that connect adjacent stacked members to each other. In one embodiment, for example, a fifth connecting member 351 may be disposed between the display panel 100 and the polymer film layer 310 to connect them to each other, a sixth connecting member 352 may be disposed between the polymer film layer 310 and the pad layer 320 to connect them to each other, a seventh connecting member 353 may be disposed between the pad layer 320 and the plate 330 to connect them to each other, and an eighth connecting member 354 may be disposed between the plate 330 and the heat dissipation member 340 to connect them to each other.

[0105] Figure 6 This is a schematic cross-sectional view of the protective film covering the window according to the embodiment, and Figure 7 This is a schematic diagram illustrating an embodiment of the process for manufacturing a protective film for windows.

[0106] refer to Figure 6 The implementation of the window cover protective film 210 may include a base layer 211 and a first protective layer 212 disposed on the base layer 211.

[0107] The base layer 211 may include a transparent polymer film. The transparent polymer film may include at least one material selected from PET, PEN, PES, PI, PAR, PC, PMMA and COC.

[0108] In embodiments, the thickness of the base layer 211 can be in the range of about 10 μm to about 300 μm, or in the range of about 30 μm to about 100 μm, for example about 50 μm. However, this disclosure is not limited thereto.

[0109] A first protective layer 212 may be disposed on the base layer 211. The first protective layer 212 may have abrasion resistance and chemical resistance to protect the cover window 220. In one embodiment, the first protective layer 212 may have hardness and modulus characteristics within a specific range, such that the cover window protective film 210 is not damaged even if the display device 10 is repeatedly folded and unfolded several times. In such an embodiment, the first protective layer 212 may have anti-fingerprint properties, so that fingerprints are not retained on the surface when the user uses the display device 10.

[0110] When layers with high hardness and modulus properties are separated from layers with anti-fingerprint properties, the bond between these layers may be weakened when the display device 10 repeatedly performs folding and unfolding operations, or fingerprints may remain due to damage to the anti-fingerprint layer. In an embodiment of the cover window protective film 210, the first protective layer 212 disposed on the base layer 211 may have high hardness and modulus properties, and may be formed as a monolayer in which components capable of ensuring anti-fingerprint properties are mixed.

[0111] In one embodiment, the first protective layer 212 may be a hard coating formed directly on one surface of the base layer 211. The first protective layer 212 may be applied directly to the base layer 211 without an adhesive layer. In an alternative embodiment, the first protective layer 212 may be attached to the base layer 211 via an adhesive layer.

[0112] The first protective layer 212 may include at least one material selected from PI, PC, PES, PEN, PPS, liquid crystal polymers (“LCP”), PMMA, acrylic polymers, and epoxy polymers, and may have a specific range of hardness and a specific range of modulus. In an embodiment, the polymer may be a polymer used for hard coatings. In an embodiment, the first protective layer 212 may also include a fluorine-based polymer to have anti-fingerprint properties.

[0113] refer to Figure 7The first protective layer 212 can be formed by applying a solution containing a first unit polymer FUP for forming a polymer capable of having a specific range of hardness and modulus, and a second unit polymer SUP for forming a polymer capable of having anti-fingerprint properties, drying the solution, and then curing the solution with UV light. In such an embodiment, when the first unit polymer FUP and the second unit polymer SUP are cured to form polymer chains, the second unit polymer SUP with anti-fingerprint properties can polymerize on the surface of the first protective layer 212 and can crosslink with the polymer formed from the first unit polymer FUP. In an embodiment, the second unit polymer SUP may comprise a fluorine-based polymer to have anti-fingerprint properties. In an embodiment, the solution containing the first unit polymer FUP and the second unit polymer SUP may also comprise a solvent and a crosslinking agent, and may also comprise a photoinitiator.

[0114] In one embodiment, the atomic ratio of fluorine (F) in the second unit polymer SUP formed on the surface of the first protective layer 212 can be determined based on the crosslinking density between the polymers formed from the first unit polymer FUP and the second unit polymer SUP. The crosslinking density can be controlled by the amount of crosslinking agent added. In such an embodiment, the hardness, modulus, abrasion resistance, and chemical resistance of the first protective layer 212 can vary depending on the crosslinking density between the polymers.

[0115] In embodiments, the modulus and hardness of the first protective layer 212, as well as the atomic ratio (at%) of fluorine (F) at its surface, can vary depending on the crosslinking density between the polymers. When the modulus becomes too large with respect to the crosslinking density of the polymer, the abrasion resistance of the first protective layer 212 may be low, and when the crosslinking density becomes too small, chemicals may be introduced into the first protective layer 212 during chemical resistance assessments, and thus chemical resistance may deteriorate. In embodiments, the first protective layer 212 of the cover window protective film 210 can have a specific range of hardness and modulus, and the atomic ratio (at%) of fluorine (F) measured at the surface of the first protective layer 212 can be within a specific range.

[0116] According to an embodiment, the first protective layer 212 may have an atomic ratio of fluorine (F) in the range of about 10 at% to about 40 at% as measured at its surface, and the ratio of the atomic ratio of fluorine (F) to the atomic ratio of carbon (C) in the polymer chain may be in the range of about 0.15 to about 1.20. This ratio may be a value obtained by dividing the atomic ratio of fluorine (F) by the atomic ratio of carbon (C). In an embodiment, the first protective layer 212 of the cover window protective film 210 may have a hardness in the range of about 0.35 gigapascals (GPa) to about 1.00 GPa and a modulus in the range of about 4.5 GPa to about 10 GPa. When the physical properties of the first protective layer 212 are within the above ranges, the cover window protective film 210 may have high abrasion resistance and chemical resistance.

[0117] In one embodiment, the atomic ratio (at%) of fluorine (F) in the first protective layer 212 can gradually increase from its lower surface to its upper surface. The lower surface of the first protective layer 212 may be the surface in contact with the base layer 211, and the upper surface may be the surface opposite to the lower surface. In such an embodiment, as described above, when the first unit polymer FUP and the second unit polymer SUP are cured to form polymer chains during the process of forming the first protective layer 212, the second unit polymer SUP, which has anti-fingerprint properties, can polymerize on the surface of the first protective layer 212 and can crosslink with the polymer formed from the first unit polymer FUP. In such an embodiment, during an ultraviolet (“UV”) irradiation process, the first unit polymer FUP and the second unit polymer SUP self-separate at a temperature of about 100°C or lower, such that the second unit polymer SUP (which is a fluorine-based polymer) can be distributed adjacent to the surface of the first protective layer 212.

[0118] Therefore, the atomic ratio (at%) of fluorine (F) in the first protective layer 212 can have a distribution that gradually increases from the lower surface to the upper surface of the first protective layer 212. That is, the atomic ratio of fluorine (F) at the upper surface of the first protective layer 212 can be greater than that at the lower surface, and the atomic ratio of fluorine (F) at the upper surface of the first protective layer 212 can be the largest. As the atomic ratio of fluorine (F) present at the upper surface of the first protective layer 212 increases, the first protective layer 212 can have high wear resistance and chemical resistance.

[0119] In one embodiment, the thickness of the first protective layer 212 can be in the range of about 1 μm to about 100 μm or about 3 μm to about 20 μm. In another embodiment, the thickness of the first protective layer 212 can be in the range of about 2 μm to about 7 μm or about 3 μm to about 6 μm. However, the thickness of the first protective layer 212 is not limited thereto.

[0120] Figure 8 This is a schematic cross-sectional view of the protective film covering the window according to an optional embodiment.

[0121] refer to Figure 8 In addition to the cover film 210 also including a second protective layer 213, this embodiment of the cover film 210 is similar to the one described above. Figure 6 The implementation of the window cover protective film 210 described is basically the same. Figure 8 The same or similar elements shown have been used in the above description Figure 6 The same reference numerals are used to mark the embodiments of the cover window protective film 210 shown, and any repeated detailed descriptions thereof will be omitted or simplified below.

[0122] refer to Figure 8 In an embodiment of the cover glass protective film 210, a second protective layer 213 may be disposed on the first protective layer 212. The second protective layer 213 may be disposed on the first protective layer 212 to provide anti-fingerprint properties to the cover glass protective film 210. The second protective layer 213 may be formed by direct deposition on the first protective layer 212.

[0123] The second protective layer 213 may include carbon, oxygen, and fluorine. In one embodiment, for example, the second protective layer 213 may include organic or inorganic compounds and fluorine compounds. In addition to the materials described above, the second protective layer 213 may include, or be formed from, conventional materials known in the art. The thickness of the second protective layer 213 may be from about 10 angstroms (Ω) to about [missing value]. Or about to approximately Within a certain range. In one embodiment, for example, the thickness of the second protective layer 213 can be approximately... to approximately Within, but not limited to, the second protective layer 213 can be formed by any method selected from sputtering, chemical vapor deposition (“CVD”), plasma-enhanced chemical vapor deposition (“PECVD”), spray pyrolysis, and electron beam (“E-Beam”), but this disclosure is not limited thereto. Because the second protective layer 213 has high interfacial adhesion to the first protective layer 212 due to the presence of fluorine (F) at the upper surface of the first protective layer 212, the configuration of an additional bonding layer can be omitted.

[0124] In an embodiment, the second protective layer 213 may have a modulus within a specific range and a hardness within a specific range to protect the cover window protective film 210 and has anti-fingerprint properties. In an embodiment, when measured at the surface of the second protective layer 213, the second protective layer 213 may have an atomic ratio of fluorine (F) in the range of about 10 at% to about 40 at% and the ratio of the atomic ratio of fluorine (F) to the atomic ratio of carbon (C) in the range of about 0.15 to about 1.20. In an embodiment, the second protective layer 213 may have a hardness in the range of about 0.35 GPa to about 1.00 GPa and a modulus in the range of about 4.5 GPa to about 10 GPa. When the physical properties of the second protective layer 213 are within the above ranges, the cover window protective film 210 may have high abrasion resistance and chemical resistance.

[0125] In one embodiment, the second protective layer 213 may contain fluorine together with the first protective layer 212. The fluorine may be uniformly distributed in the second protective layer 213. That is, the second protective layer 213 differs from the first protective layer 212 in that it does not have the gradual increase or decrease in the atomic ratio of fluorine as seen in the first protective layer 212. In another embodiment, the atomic ratio of fluorine (F) may gradually increase from the lower surface to the upper surface of the first protective layer 212, and this increase may be due to the second protective layer 213 at the interface between the first and second protective layers 212, and the atomic ratio of fluorine (F) may be uniformly maintained within the second protective layer 213.

[0126] Other alternative implementations will be described below. Figure 9 and Figure 10 Embodiments of display devices having various stacked structures are shown.

[0127] Figure 9 This is a cross-sectional view of the display panel according to an optional embodiment, and Figure 10 This is a cross-sectional view of a display panel according to another alternative embodiment.

[0128] refer to Figure 9 Except for omitting the pad 320, the seventh connecting member 353, the plate 330, and the eighth connecting member 354, this embodiment of the display device 10 is similar to... Figure 3 The implementation of the display device 10 is basically the same.

[0129] refer to Figure 10 Such an implementation of the display device 10 has the same characteristics as... Figure 4 The display device 10 has the same stacking structure as the implementation of the display device 10, but with Figure 4The difference in the implementation of the display device 10 is that the folding is performed by folding outward with the display surface facing outward.

[0130] because Figure 9 and Figure 10 The configuration of the implementation method can be the same as the above reference. Figure 3 The descriptions are essentially the same, so any repeated detailed descriptions will be omitted.

[0131] The implementation methods will be described in more detail below through preparation examples and experimental examples.

[0132] <Preparation Example 1: Preparation of Window Cover Protective Film>

[0133] Multiple cover window protective film samples were prepared, and each cover window protective film sample had the following characteristics: Figure 6 The layered structure shown is illustrated. Except for the different proportions of the second unit polymer (fluorine-based component) forming the fluorine-based polymer with anti-fingerprint properties, samples #1, #2, and #3 were prepared in the same manner. Furthermore, samples with the following characteristics were prepared... Figure 8 The laminated protective film sample #4 is shown. Sample #4 was prepared by forming a second protective layer on the upper surface of sample #2 using an electron beam.

[0134] The surface composition ratio of the first protective layer of samples #1, #2, and #3 was measured, and... Figures 11 to 13 And as shown in Table 1 below. Figure 11 This is a graph showing the composition of sample #1 according to etching time. Figure 12 This is a graph showing the composition of sample #2 according to etching time, and Figure 13 This is a graph showing the composition of sample #3 according to the etching time. Here, etching time refers to the time spent performing etching in the thickness direction.

[0135] Surface composition measurements were performed using an X-ray photoelectron spectroscopy (XPS) instrument from Thermo Scientific Corporation. Surface composition was measured using Al ka X-rays (1486.6 eV) at a spot size of 400 μm, an ion source emission energy of 4 keV (Ar source) via gas cluster ion sputtering, and an ion current of 7 nanoamperes (nA). The [F] / [C] composition ratio was calculated using the atomic percentages (at%) of fluorine (F) and carbon (C).

[0136] [Table 1]

[0137]

[0138]

[0139] refer to Figures 11 to 13 As shown in Table 1 above, the atomic ratio of fluorine (F) at the surface of each of samples #1, #2, and #3 is in the range of 10 at% to 40 at% and the ratio of the atomic ratio of fluorine (F) to the atomic ratio of carbon (C) ([F] / [C]) is in the range of 0.15 to 1.20. Furthermore, it can be observed that the atomic ratio of fluorine (F) gradually decreases as the first protective layer is etched in the thickness direction. In other words, the atomic ratio of fluorine (F) gradually decreases towards the surface of the first protective layer.

[0140] Of these samples, sample #2 was prepared by repeating the process several times and its surface composition was evaluated. The results are given in Table 2 below.

[0141] [Table 2]

[0142]

[0143] Referring to Table 2, in several assessments of the surface composition, it can be found that the ratio of fluorine to carbon is 0.15 or greater, and except for the second assessment, the atomic ratio of fluorine at the surface is in the range of 10 at% to 40 at%.

[0144] <Experimental Example 1: Measurement of the Physical Properties of Window Covering Film>

[0145] The hardness and modulus of the first protective layer in each of the sample #1, sample #2, and sample #3 of the preparation example were measured. The hardness and modulus were measured using the indenter evaluation method (ISO 14577), which specifies the measurement method in... Figure 14 The results are shown in [the document / reference], and their results are in [the document / reference]. Figure 15 and Figure 16 And as shown in Table 13 below.

[0146] Figure 14 This is a schematic cross-sectional view illustrating an embodiment of a method for measuring the modulus and hardness of the first protective layer using an indenter. Figure 15 It is a graph showing the relationship between indentation depth and load, and Figure 16 This is a graph showing the relationship between the indentation depth of the first protective layer and the load according to Experimental Example 1. Figure 14 and Figure 15 In the middle, h max It refers to the indentation depth at the point where the maximum load is reached, and h c This refers to the actual indentation depth (excluding the influence of surrounding indentations).

[0147] To measure hardness and modulus, an ultra-nano hardness tester (model: GmbH, manufactured by Anton-Paar Corporation) was used, with a Berkovich diamond tip as the indenter. In the indenter evaluation method, the prepared sample was attached to a flat holder and placed on a plate. Fifteen surface measurement points were selected using a microscope, and the measurement conditions were then input into a load-indentation depth curve. The modulus and hardness were calculated using the Oliver & Parr model equations based on the measured curves.

[0148] Specifically, refer to Figure 14 The cover film 210 was cut into 2cm x 2cm pieces, attached to a flat retainer, and then placed on a plate. Subsequently, an indenter RBL was pressed to apply a force P of a maximum load of 0.2 millinewtons (mN) to the surface of the first protective layer 212 in a direction Z perpendicular to the end surface of the indenter RBL, and the indentation depth was measured while pressing was performed at a loading / unloading rate (pressing speed) of 0.2 millinewtons / minute (mN / min). Tests were performed at 15 points, and the indentation depth was expressed as the average of the results of several tests.

[0149] refer to Figure 15 The load-indentation depth curve can be obtained using the indenter evaluation method. In the load-indentation depth curve, as the indentation load of the indenter increases, the indentation depth also increases, and the maximum indentation depth h is obtained at the maximum indentation load. max As the indenter is unloaded, the indentation depth decreases, and the greater the restoring force, the smaller the indentation depth after the indenter is unloaded. The actual indentation depth can be represented by the slope S of the curve during unloading.

[0150] [Table 3]

[0151]

[0152] First, refer to Figure 16 The load-indentation depth curves obtained through Experimental Example 1 are shown. Under a maximum indentation load of 0.10 mN / min, each sample exhibited a maximum indentation depth ranging from 0.10 μm to 0.14 μm, and a recovered indentation depth ranging from 0.05 μm to 0.08 μm after unloading. Using these load-indentation depth curves, the modulus and hardness shown in Table 3 above were calculated using the Oliver & Parr model equations.

[0153] Referring to Table 3 above, each of samples #1, #2, and #3 exhibits a hardness ranging from 0.35 GPa to 1.00 GPa. Furthermore, sample #2 exhibits a modulus ranging from 4.5 to 10 GPa, but each of samples #1 and #3 exhibits a modulus less than 4.5 GPa.

[0154] <Experimental Example 2: Evaluation of the Abrasion Resistance and Chemical Resistance of Window Covering Film>

[0155] Abrasion resistance and chemical resistance were evaluated using the prepared samples. Abrasion resistance was evaluated by measuring the number of reciprocating movements required to observe surface damage when a 6.2mm × 150mm industrial pencil eraser from MINOAN Corporation was repeatedly moved back and forth on the upper surface of the first protective layer. During the evaluation, the eraser was subjected to a load of 1 kg, with a reciprocating speed of 40 reciprocating movements / min, a stroke of 15 mm, and the eraser protruding 5 mm from one end of the evaluation rod. Furthermore, during the abrasion resistance evaluation, 99.3% ethanol was introduced into each 1 ml of eraser every 50 reciprocating movements, while simultaneously performing a chemical resistance evaluation. The results were... Figure 17 and Figure 18 And as shown in Table 4 below. In Table 4 below, "K" indicates that the pencil and eraser are moved back and forth 1000 times. Figure 17 It is a graph showing the relationship between wear resistance and modulus, [F] / [C] component ratio, and hardness, and Figure 18 It is a graph showing the relationship between chemical resistance and modulus, [F] / [C] component ratio and hardness, and in which, Figure 17 and Figure 18 The "R" in 2 " is the coefficient of determination. The coefficient of determination is a constant that describes the degree of agreement between experimental and predicted values.

[0156] [Table 4]

[0157]

[0158] Referring to Table 4 above, each of Sample #1, Sample #2, and Sample #3 exhibits abrasion resistance of 3K or higher. Furthermore, Sample #2 exhibits chemical resistance of 1K or higher, but each of Sample #1 and Sample #3 exhibits chemical resistance less than 1K.

[0159] refer to Figure 17 As wear resistance increases, hardness tends to increase proportionally, but modulus and [F] / [C] component ratio tend to decrease. Furthermore, refer to... Figure 18 As chemical resistance increases, hardness tends to decrease, but modulus and [F] / [C] component ratio tend to increase proportionally.

[0160] <Experiment Example 3: Evaluation of the Properties of Cover Window Protective Film>

[0161] The surface composition ratio, hardness, modulus, abrasion resistance, and chemical resistance of the second protective layer of sample #4, prepared according to the same conditions as in Experimental Examples 1 and 2, were measured. The results are given in Table 5.

[0162] [Table 5]

[0163]

[0164] Referring to Table 5 above, in sample #4, the atomic ratio of fluorine (F) at its surface ranges from 10 at% to 40 at%, and the ratio of the atomic ratio of fluorine (F) to the atomic ratio of carbon (C) ([F] / [C]) ranges from 0.15 to 1.2. Furthermore, sample #4 exhibits a hardness in the range of 0.35 GPa to 1.00 GPa and a modulus in the range of 4.5 GPa to 10 GPa. Additionally, sample #4 exhibits abrasion resistance of 3K or higher and chemical resistance of 1K or higher.

[0165] According to embodiments of the present invention, the first protective layer of the cover window protective film may have a specific range of hardness and modulus, and the atomic ratio (at%) of fluorine (F) measured at the surface of the first protective layer may be within a specific range, such that the cover window protective film is not damaged even if the display device is repeatedly folded and unfolded several times. In embodiments, the first protective layer of the cover window protective film may have anti-fingerprint properties, such that fingerprints are not retained on the surface when the user uses the display device.

[0166] This invention should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

[0167] Although the invention has been specifically shown and described with reference to embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit or scope of the invention as defined by the appended claims.

Claims

1. A cover window protective film, comprising: a base layer; a first protective layer disposed on the base layer; and a second protective layer disposed on the upper surface of the first protective layer, wherein the first protective layer includes a lower surface adjacent to the base layer and an upper surface opposite to the lower surface, the first protective layer includes a fluorine-based compound, and has an atomic ratio of fluorine gradually increasing from the lower surface toward the upper surface, wherein the atomic ratio of fluorine at the upper surface of the first protective layer is in a range of 10 at% to 40 at%, wherein the upper surface of the first protective layer has a modulus in a range of 4.5 GPa to 10 GPa, wherein the upper surface of the first protective layer has a hardness in a range of 0.35 GPa to 1.00 GPa, and wherein an upper surface of the second protective layer has a modulus in a range of 4.5 GPa to 10 GPa and a hardness in a range of 0.35 GPa to 1.00 GPa. The atomic ratio of fluorine is the highest at the upper surface of the first protective layer.

2. The cover window protection film of claim 1, wherein, 3.The cover window protective film according to claim 1, wherein, the first protective layer further includes carbon, and a ratio of the atomic ratio of fluorine to an atomic ratio of carbon at the upper surface of the first protective layer is in a range of 0.15 to 1.

20. The atomic ratio of fluorine and the atomic ratio of carbon are values measured by an X-ray photoelectron spectrometer.

4. The cover window protection film of claim 3, wherein, The modulus and the hardness are values measured by a nanoindenter.

5. The cover window protection film of claim 1, wherein, The first protective layer has a thickness in a range of 2 μm to 7 μm.

6. The cover window protection film of claim 1, wherein, 7.A display device, comprising: a display panel; and a front stack structure disposed on a front surface of the display panel, wherein the front stack structure includes a cover window and a cover window protective film attached to the cover window, the cover window protective film includes a base layer, a first protective layer disposed on the base layer, and a second protective layer disposed on an upper surface of the first protective layer, wherein the first protective layer includes a fluorine-based compound, the first protective layer includes a lower surface adjacent to the base layer and an upper surface opposite to the lower surface, and the first protective layer has an atomic ratio of fluorine higher at the upper surface of the first protective layer than at the lower surface of the first protective layer, wherein the atomic ratio of fluorine at the upper surface of the first protective layer is in a range of 10 at% to 40 at%, wherein the upper surface of the first protective layer has a modulus in a range of 4.5 GPa to 10 GPa, wherein the upper surface of the first protective layer has a hardness in a range of 0.35 GPa to 1.00 GPa, and wherein an upper surface of the second protective layer has a modulus in a range of 4.5 GPa to 10 GPa and a hardness in a range of 0.35 GPa to 1.00 GPa. The front stack structure further includes:

8. The display device of claim 7, wherein, a polarizing member disposed between the display panel and the cover window, and a polarizing member coupling member attaching the polarizing member to the front surface of the display panel. ​ 9. The display device of claim 8, wherein, The front stack structure further includes: an impact absorbing layer disposed between the polarizing member and the cover window, and an impact absorbing layer coupling member attaching the impact absorbing layer to the polarizing member. 10.The display device of claim 7, further comprising: a back stack structure disposed on a back surface of the display panel, and the back stack structure includes a polymer film layer disposed on a back side of the display panel, a cushion layer disposed on a back side of the polymer film layer, a plate disposed on a back side of the cushion layer, and a heat dissipation member disposed on a back side of the plate. 11.The display device of claim 7, wherein: the first protective layer further includes carbon, a ratio of the atomic ratio of fluorine to the atomic ratio of carbon at the upper surface of the first protective layer is in a range of 0.15 to 1.20, and the atomic ratio of fluorine and the atomic ratio of carbon are values measured by an X-ray photoelectron spectrometer. 12.The display device of claim 7, wherein: the modulus and the hardness are values measured by a nanoindenter.

13. The display device of claim 7, wherein, the first protective layer has a thickness in a range of 2 μm to 7 μm.

14. The display device of claim 7, wherein, the display panel displays an image in a forward direction.

15. The display device of claim 7, wherein, the display device is an inward foldable display device in which a display surface is folded inward or an outward foldable display device in which the display surface is folded outward.

Images