Display device

Abstract

A display device is disclosed. The display device includes a display panel foldable about a fold axis, a window on the display panel, a protective film on the window, and a plurality of adhesive layers between the window and the protective film. The adhesive layers include a first adhesive layer on the window and a second adhesive layer on the first adhesive layer. The first adhesive layer includes a side chain crystalline polymer, and a modulus of the second adhesive layer is less than a modulus of the first adhesive layer.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0040688, filed on March 29, 2021, and all benefits arising therefrom, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to display devices. More specifically, this disclosure relates to foldable display devices. Background Technology

[0004] Display devices provide information to users by displaying various images on a screen. Flexible display devices, including foldable flexible display panels, are under development. Because the shape of flexible display devices can be changed in various ways, the ease of transportation of flexible display devices is improved, regardless of the original screen size. Summary of the Invention

[0005] A protective film is applied to a display device to protect its display surface. However, the protective film can easily peel off from the display surface depending on the operation of the display device, or it can damage the display surface during the replacement of the protective film.

[0006] This disclosure provides a display device including a protective film that will not peel off even if the display device is repeatedly folded and unfolded, and will not damage the components of the display device when the protective film is replaced.

[0007] An embodiment provides a display device comprising a display panel foldable about a folding axis extending in a first direction, a window on the display panel, a protective film on the window, and a plurality of adhesive layers between the window and the protective film. The adhesive layers include a first adhesive layer on the window and a second adhesive layer on the first adhesive layer. The first adhesive layer comprises a side-chain crystalline polymer, and the modulus of the second adhesive layer is less than that of the first adhesive layer.

[0008] The first adhesive layer may have a first adhesive force at room temperature and a second adhesive force at a temperature equal to or greater than about 70 degrees Celsius, and the second adhesive force is equal to or less than about 50% of the first adhesive force.

[0009] At a temperature equal to or greater than about 70 degrees Celsius, the adhesive force of the second adhesive layer can be greater than that of the second adhesive force.

[0010] The side-chain crystalline polymer may include at least one of (meth)acrylate hexadecyl ester copolymer, (meth)acrylate octadecyl ester copolymer, (meth)acrylate eicosyl ester copolymer and (meth)acrylate dodecyl ester copolymer.

[0011] The thickness of the first adhesive layer can be less than the thickness of the second adhesive layer.

[0012] The first adhesive layer may have a thickness equal to or greater than about 5 μm and equal to or less than about 25 μm.

[0013] The second adhesive layer may have a thickness equal to or greater than about 10 μm and equal to or less than about 100 μm.

[0014] The modulus of the second adhesive layer can be approximately 0.2 MPa at -20 degrees Celsius.

[0015] At least one of the first adhesive layer and the second adhesive layer may further include a foaming agent.

[0016] The content of the foaming agent in the first adhesive layer can be equal to or less than about 3%.

[0017] The content of the foaming agent in the second adhesive layer can be equal to or less than about 3%.

[0018] The display device may further include a support module below the display panel, and the display panel may include a first non-folding region, a folding region, and a second non-folding region arranged in a second direction intersecting the first direction. The support module may include a buffer layer below the display panel and a support plate below the buffer layer.

[0019] The support plate may include a first support member that overlaps with the first non-folded region and a second support member that is spaced apart from the first support member in a second direction and overlaps with the second non-folded region.

[0020] The support plate may have multiple openings defined therein to overlap with the folded area.

[0021] An embodiment provides a display device including a foldable display panel, a window on the display panel, a protective film on the window, and a plurality of adhesive layers between the window and the protective film. The adhesive layers include a first adhesive layer on the window and a second adhesive layer on and in contact with the first adhesive layer. The first adhesive layer has a first adhesive force at room temperature and a second adhesive force at a temperature equal to or greater than about 70 degrees Celsius; the second adhesive layer has a third adhesive force at a temperature equal to or greater than about 70 degrees Celsius; and the second adhesive force is less than the third adhesive force and is equal to or less than about 50% of the first adhesive force.

[0022] The first adhesive layer may have a thickness equal to or greater than about 5 μm and equal to or less than about 25 μm, and the second adhesive layer may have a thickness equal to or greater than about 10 μm and equal to or less than about 100 μm.

[0023] The first adhesive layer may include a side-chain crystalline polymer.

[0024] The side-chain crystalline polymer may include at least one of (meth)acrylate hexadecyl ester copolymer, (meth)acrylate octadecyl ester copolymer, (meth)acrylate eicosyl ester copolymer and (meth)acrylate dodecyl ester copolymer.

[0025] The modulus of the second adhesive layer can be less than that of the first adhesive layer.

[0026] At least one of the first adhesive layer and the second adhesive layer may further include a foaming agent.

[0027] According to one or more embodiments described above, the display device is provided with a protective film that will not be easily peeled off even if the display device is repeatedly folded and unfolded.

[0028] Furthermore, when replacing the protective film, it can be easily replaced without damaging the components of the display device. Attached Figure Description

[0029] The above and other advantages of this disclosure will become apparent when considered in conjunction with the accompanying drawings, and by referring to the following detailed description, in which:

[0030] Figure 1 This is a perspective view showing an embodiment of the display device;

[0031] Figures 2A to 2C This is a perspective view showing an embodiment of the display device;

[0032] Figure 3 This is an exploded perspective view showing an embodiment of the display device;

[0033] Figure 4 This is a cross-sectional view showing an embodiment of the display panel;

[0034] Figure 5 This is a cross-sectional view illustrating an embodiment of the display device;

[0035] Figure 6A It is a graph showing the relationship between temperature and adhesive force of the first adhesive layer and the comparative adhesive layer;

[0036] Figure 6B This is a schematic diagram illustrating an embodiment of the molecular structure of the first adhesive layer;

[0037] Figures 7A to 7C This is a cross-sectional view illustrating an embodiment of the display device;

[0038] Figure 8A and Figure 8B This is a cross-sectional view illustrating an embodiment of the display device; and

[0039] Figures 9A to 9D This is a perspective view illustrating an embodiment of the process for replacing the protective film. Detailed Implementation

[0040] This disclosure can be modified and implemented in many different forms, and therefore embodiments will be illustrated in the accompanying drawings and described in detail below. However, this disclosure should not be limited to the disclosed forms and should be construed as including all modifications, equivalents, or substitutions contained within the spirit and scope of this disclosure.

[0041] In this disclosure, it will be understood that when an element or layer is referred to as being associated with another element or layer, such as “on” another element or layer, “connected to” or “linked to” another element or layer, it may be directly on, directly connected to or directly linked to the other element or layer, or there may be an intervening element or layer. Conversely, when an element or layer is referred to as being associated with another element or layer, such as “directly on” another element or layer, “directly connected to” or “directly linked to” another element or layer, there are no other elements or layers, or intervening elements or layers.

[0042] The same reference numerals denote the same elements throughout the drawing. Reference numerals may indicate a single element or multiple elements. For example, reference numerals that denote elements in the singular form in the drawing may be used within the text of the specification to indicate multiple singular elements.

[0043] In the accompanying drawings, the thickness, proportions, and dimensions of the components are exaggerated in order to effectively depict the technical content.

[0044] It will be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this disclosure, the first element discussed below may be referred to as the second element.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. For example, “element” has the same meaning as “at least one element”, unless the context clearly indicates otherwise. “At least one” will 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.

[0046] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “up,” etc., may be used in this document to describe the relationship between one element or feature and another element or feature as shown in the figure.

[0047] It will also be understood that, when used in this specification, the terms “comprising” and / or “including” specify the presence of the stated features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or groups thereof.

[0048] As used herein, “about” or “approximately” includes the value as well as the average of the specific value within an acceptable range of deviations determined by a person skilled in the art, considering the measurement in question and the errors associated with the measurement of the specific quantity (i.e., limitations of the measurement system). For example, “about” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the value.

[0049] Unless otherwise specified, 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 will also be understood that terms, such as those defined in common dictionaries, shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0050] Embodiments are described herein with reference to sectional views, which are schematic illustrations of idealized embodiments. Therefore, deviations from the illustrated shapes are expected due to factors such as manufacturing techniques and / or tolerances. Consequently, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but will include shape deviations, for example, due to manufacturing processes. For instance, regions shown or described as flat may generally have rough and / or non-linear characteristics. 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 represent the precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0051] In the following description, embodiments of the display device 1000 will be described in detail with reference to the accompanying drawings.

[0052] Figure 1 as well as Figures 2A to 2C This is a perspective view showing an embodiment of the display device 1000. Figure 1 An unfolded display device 1000 is shown, and Figures 2A to 2C A foldable display device 1000 is shown.

[0053] The display device 1000 can be a device activated in response to an electrical signal. The display device 1000 can be applied to various electronic devices. In embodiments, for example, the display device 1000 can be applied to electronic devices such as mobile phones, smartwatches, tablet computers, laptop computers, computers, smart TVs, etc. The display device 1000 can be applied to other electronic devices, as long as it does not depart from the scope of the invention. Figure 1 A display device 1000 for use in a mobile phone is shown.

[0054] The display device 1000 can display images to the outside of the display device 1000. The front surface of the display device 1000 may include a display area DA and a non-display area NDA. The front surface of the display device 1000 may be substantially parallel to a plane defined by a first direction DR1 and a second direction DR2 that intersect each other. The front surface of the display device 1000 may correspond to a display surface through which an image is displayed.

[0055] The display device 1000 can display an image at a display area DA. The display area DA of the display device 1000 can be substantially parallel to the plane defined by the first direction DR1 and the second direction DR2. The unfolded display device 1000 can display an image on the third direction DR3. Various components or layers of the display device 1000 may include the display area DA and the non-display area NDA corresponding to the display area DA and the non-display area NDA described for the display device 1000.

[0056] A third direction DR3, intersecting the first direction DR1 and the second direction DR2, can indicate the thickness direction of the display device 1000 and its various components or layers. The front (or upper) and rear (or lower) surfaces of each component of the display device 1000 can be opposite to each other on or along the third direction DR3, and the normal direction of each of the front and rear surfaces can be substantially parallel to the third direction DR3. The directions indicated by the first direction DR1, the second direction DR2, and the third direction DR3 can be opposite to each other and can be changed to other directions.

[0057] The non-display area NDA can be a region in which no image is displayed (e.g., a planar region). The non-display area NDA can be defined as being adjacent to the display area DA. Figure 1 As shown, the non-display area NDA may surround the display area DA; however, it should not be limited to or restricted by this. According to an embodiment, the non-display area NDA may be defined as being adjacent only to one side of the display area DA, or it may be omitted.

[0058] The display device 1000 may be a foldable and / or bendable flexible display device. In this disclosure, the term "flexible" as used herein with respect to a component may mean that the component has a bendable property, and a flexible display device may have a structure that can be bent into a fully foldable form; however, it should not be limited thereto or construed as such. A flexible display device may have a portion of its structure that is bendable.

[0059] The display device 1000 may include a folding region FA and one or more non-folding regions, such as non-folding regions NFA1 and NFA2. The display device 1000 may be foldable at the folding region FA. The unfolded display device 1000 may have the folding region FA set flat, and the folded or bent display device 1000 may have the folding region FA set curved according to the folding operation of the display device 1000. Even when the display device 1000 is folded, the non-folding regions NFA1 and NFA2 may be flat. Each of the folding region FA and the non-folding regions NFA1 and NFA2 may be multiple and should not be particularly limited. Figure 1 A first non-folded region NFA1, a folded region FA, and a second non-folded region NFA2 are shown arranged sequentially on or along the first direction DR1.

[0060] refer to Figures 2A to 2C The display device 1000 can be folded around an imaginary folding axis (hereinafter, folding axis FX) extending in one direction. Figures 2A to 2C A display device 1000 is shown folded about a folding axis FX extending in a second direction DR2; however, the direction in which the folding axis FX extends should not be limited to or restricted by this. According to an embodiment, the folding axis FX may extend in a first direction DR1. In this case, non-folding regions NFA1 and NFA2 may be arranged in the second direction DR2, with the folding region FA interposed between them.

[0061] The display device 1000 can be folded at an angle around the folding axis FX. Figure 2A and Figure 2B A partially folded display device 1000 is shown, and Figure 2C The display device 1000 is shown folded completely at an angle of approximately 180 degrees.

[0062] refer to Figure 2AIn this embodiment, the folding axis FX may be defined below the rear surface of the display device 1000 opposite to the display surface, and the folding area FA of the display device 1000 may form a curved surface convex with respect to the folding axis FX according to the folding operation. This may be referred to as the outward folding state of the outward folding display device 1000. The outward folding display device 1000 exposes a portion of the display area DA of the display device 1000 to the outside of the display device 1000 (e.g., facing outward). Although not shown in the figures, the display device 1000 folded completely outward at an angle of approximately 180 degrees sets the first non-folding area NFA1 and the second non-folding area NFA2 to face opposite directions to display images in opposite directions.

[0063] refer to Figure 2B In an embodiment, the folding axis FX may be defined above the front surface of the display device 1000, and the folding region FA of the display device 1000 may form a curved surface recessed relative to the folding axis FX. This may be referred to as the inward-folded state of the inward-folded display device 1000. The inward-folded display device 1000 arranges multiple portions of the display region DA so that they face each other relative to one direction. In the inward-folded display device 1000, the first non-folded region NFA1 may face the second non-folded region NFA2. Figure 2C As shown, the display device 1000, which is folded completely inward at an angle of approximately 180 degrees, can have its display area DA set so that it is not exposed to the outside of the display device 1000 (e.g., facing inward).

[0064] The folding operation of the display device 1000 is not limited to the embodiments described above, and can be designed in various ways.

[0065] Figure 3 This is an exploded perspective view showing an embodiment of the display device 1000. Figure 3 It is shown Figure 1 The diagram shows an exploded perspective view of an embodiment of the display device 1000. The display device 1000 may include a support module 300, a display module 100, and a protective module 200 sequentially stacked on a third-direction DR3. Each of the support module 300, display module 100, and protective module 200 is foldable about a folding axis FX. That is, the support module 300, display module 100, and protective module 200, as well as the various components or layers therein, can be folded together with each other when the display device 1000 is folded.

[0066] The display module 100 may be a module that generates an image in response to an electrical signal. The display module 100 may include a display panel DP and a window WP.

[0067] Display panel DP can generate and / or display images. However, display panel DP can be a liquid crystal display panel or a light-emitting display panel, but should not be particularly limited thereto. In embodiments, for example, a light-emitting display panel can be an organic light-emitting display panel or a quantum dot light-emitting display panel. The light-emitting layer of an organic light-emitting display panel may include organic light-emitting materials. The light-emitting layer of a quantum dot light-emitting display panel may include quantum dots or quantum rods. In the following description, an organic light-emitting display panel will be used as a representative example of a display panel DP.

[0068] A window WP can be installed on the display panel DP to protect it. The window WP can face the display panel DP. The window WP can reduce or effectively prevent damage or malfunction of the display panel DP due to external impacts on the display device 1000. The window WP may include an optically transparent insulating material. Therefore, the image generated by the display panel DP can be transmitted through the window WP so that it is visible from outside the display device 1000.

[0069] The window WP may include a flexible material. The window WP can be repeatedly folded or unfolded around the folding axis FX. Therefore, depending on the operation of the display device 1000, the shape of the window WP can be changed to correspond to the shape of the display panel DP.

[0070] The window WP may include a thin glass or a synthetic resin film. The thin glass included in the window WP may have a thickness equal to or less than about 100 micrometers, for example, about 30 micrometers; however, the thickness of the thin glass included in the window WP should not be limited thereto or constrained by this. The synthetic resin film included in the window WP may include a polyimide (PI) film or a polyethylene terephthalate (PET) film.

[0071] The window WP can have a single-layer or multi-layer structure. In an embodiment, for example, the window WP may include a plurality of synthetic resin films bonded to each other by an adhesive, an organic substrate and a synthetic resin film bonded to the organic substrate by an adhesive, or a thin glass and a synthetic resin film bonded to the thin glass by an adhesive; however, it should not be particularly limited.

[0072] Although not shown in the figures, the display module 100 may include at least one functional layer disposed between the display panel DP and the window WP. As an example, the functional layer may be an anti-reflective layer to reduce or effectively prevent the reflection of external light. The anti-reflective layer can reduce or effectively prevent the elements of the display panel DP from being visible from the outside due to external light incident on the front surface of the display device 1000. The anti-reflective layer may include at least one of a retarder, a polarizer, and a color filter.

[0073] The protection module 200 may be disposed on the display module 100 (e.g., facing the display module 100) to reduce or effectively prevent the display module 100 from external impacts. The protection module 200 may be in contact with the display module 100. As an example, the protection module 200 may be attached to the window WP of the display module 100. The protection module 200 may include multiple adhesive layers and a protective film PF (see [link to relevant documentation]). Figure 5 This will be described in detail later.

[0074] The protection module 200 may include an optically transparent material. Therefore, the image generated by the display panel DP and emitted from the window WP can be transmitted through the protection module 200 so that it is visible from outside the display device 1000.

[0075] The protective module 200 may include a flexible material. The protective module 200 can be repeatedly unfolded or folded around the folding axis FX. Therefore, the shape of the protective module 200 can be changed to correspond to the shape of the display module 100, wherein the shape of the display module 100 changes according to the operation of the display device 1000.

[0076] The support module 300 can be disposed on the rear surface of the display module 100 and can support the display module 100. The support module 300 may include a buffer layer 310 and a support plate 320.

[0077] A buffer layer 310 may be disposed on the rear surface of the display module 100. The buffer layer 310 can absorb external impacts applied to the display module 100. As an example, the buffer layer 310 may include sponge, foam, or polyurethane resin. However, the material used for the buffer layer 310 should not be limited to or restricted by this, and the buffer layer 310 may include various materials, as long as the buffer layer 310 can protect the display module 100 and absorb external impacts.

[0078] A support plate 320 may be disposed on the rear surface of the buffer layer 310 to support the display module 100 and to reduce or effectively prevent deformation of the display module 100. The support plate 320 may face the display module 100, with the buffer layer 310 positioned between them. The support plate 320 may have a solid plate shape corresponding to the shape of the display panel DP. The support plate 320 may have a structure with increased flexibility in areas overlapping or corresponding to the folding area FA; however, it should not be limited to or construed as such. According to an embodiment, the support plate 320 may comprise two or more plates spaced apart from each other, with the folding area FA interposed therebetween, and this will refer to… Figure 8A and Figure 8B Provide a detailed description.

[0079] The support plate 320 may comprise a material having a relatively high modulus. As an example, the support plate 320 may comprise a metallic material. Specifically, the support plate 320 may comprise stainless steel, aluminum, or an alloy thereof. However, the materials used for the support plate 320 should not be limited to or restricted by this, and the support plate 320 may comprise a variety of materials as long as they can support the display panel DP.

[0080] Although not shown in the figures, the display device 1000 may also include an input sensing unit disposed on the display panel DP. The display device 1000 can sense external inputs applied to it in various forms. In embodiments, external inputs may include, for example, pressure, temperature, or light. External inputs may include external inputs that are close to or near the display device 1000 at a distance (e.g., hover input), and touch inputs (e.g., contact) via input tools (such as body parts (e.g., a user's hand), pens, etc.).

[0081] Figure 4 This is a cross-sectional view illustrating an embodiment of a display panel DP. The display panel DP may include a base substrate SUB, a circuit layer DP-CL, a display element layer DP-OL, and a packaging layer TFE.

[0082] The base substrate SUB can be flexible. The base substrate SUB can have a single-layer or multi-layer structure. The base substrate SUB can include a plastic substrate, a glass substrate, a metal substrate, or an organic / inorganic composite substrate. The base substrate SUB can include a synthetic resin film. In embodiments, for example, the synthetic resin film can include polyimide-based resins, acrylic-based resins, ethylene-based resins, epoxy-based resins, urethane-based resins, cellulose-based resins, and phthalic anhydride-based resins. However, the synthetic resin film should not be limited thereto or restricted by these limitations.

[0083] A circuit layer DP-CL can be disposed on a base substrate SUB. The circuit layer DP-CL may include an insulating layer, semiconductor patterns, conductive patterns, and signal lines. The insulating layer, semiconductor layer, and conductive layer can be formed on the base substrate SUB by a coating or deposition process. Then, the insulating layer, semiconductor layer, and conductive layer can be selectively patterned by a photolithography process, and thus the insulating layer, semiconductor patterns, conductive patterns, and signal lines included in the circuit layer DP-CL can be formed or disposed.

[0084] The display element layer DP-OL can be disposed on the circuit layer DP-CL. The display element layer DP-OL may include a light-emitting element configured to correspond to the display area DA of the display device 1000. In an embodiment, for example, the display element layer DP-OL may include an organic light-emitting element, quantum dot, quantum rod, micron LED, or nano LED as the light-emitting element.

[0085] The display panel DP may include a plurality of pixels that generate an image in response to electrical signals. Each pixel may include a light-emitting element contained in the display element layer DP-OL and a thin-film transistor contained in the circuit layer DP-CL and electrically connected to the light-emitting element. Pixels may be arranged in the display area DA; however, they should not be limited thereto or restricted by this. Some pixels may be arranged in the non-display area NDA.

[0086] The encapsulation layer TFE can be configured on the circuit layer DP-CL to cover the display element layer DP-OL. The encapsulation layer TFE may include multiple inorganic layers and organic layers disposed between the inorganic layers; however, the layers included in the encapsulation layer TFE should not be limited thereto or restricted by this.

[0087] Inorganic layers included in the TFE encapsulation layer can protect pixels from moisture and oxygen. As examples, inorganic layers may include silicon nitride, silicon oxide, silicon oxynitride, titanium oxide, or aluminum oxide. Organic layers included in the TFE encapsulation layer can protect pixels from foreign matter such as dust particles. As examples, organic layers may include acrylic-based organic layers; however, the materials used for inorganic and organic layers should not be limited to or construed as such.

[0088] Figure 5 This is a cross-sectional view showing an embodiment of the display device 1000. Figure 5 It is along Figure 3 The cross-sectional view of the display device 1000 is shown by line I-I'. Figure 5 The display module 100 and protection module 200 of the display device 1000 are schematically shown.

[0089] The protective film PF may include a polymer film. As an example, the polymer film may include at least one polymer resin selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene naphthalate (PEN), polystyrene (PS), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyethersulfone (PES), polypropylene (PP), polyamide (PA), modified polyphenylene ether (m-PPO), polyoxymethylene (POM), polysulfone (PSU), polyphenylene sulfide (PPS), polyimide (PI), polyethyleneimine (PEI), polyetheretherketone (PEEK), polyamide-imide (PAI), polyarylate (PAR), and thermoplastic polyurethane (TPU).

[0090] The display device 1000 may have folding characteristics and shock resistance, which vary depending on the thickness of the protective film PF. When the protective film PF is too thin, the display device 1000 may be damaged by external impacts, and when the protective film PF is too thick, the folding characteristics of the display device 1000 may be reduced. As an example, the thickness of the protective film PF may be equal to or greater than about 25 micrometers (μm) and equal to or less than about 200 μm. More specifically, the thickness of the protective film PF may be equal to or greater than about 50 μm and equal to or less than about 100 μm. However, the thickness of the protective film PF should not be limited to or restricted by these limitations.

[0091] A first adhesive layer AD1 and a second adhesive layer AD2 can be disposed between the display module 100 and the protective film PF, and the display module 100 can be attached to the protective film PF. The first adhesive layer AD1 can contact the upper surface WP-U of the window WP. Multiple elements can form an interface or boundary therebetween upon contact. The first adhesive layer AD1 can be closer to the display module 100 than the second adhesive layer AD2. The second adhesive layer AD2 can contact the upper surface of the first adhesive layer AD1 and the rear surface of the protective film PF.

[0092] Each of the first adhesive layer AD1 and the second adhesive layer AD2 may comprise a base resin of a pressure-sensitive adhesive. As an example, each of the first adhesive layer AD1 and the second adhesive layer AD2 may comprise at least one of an acrylic-based resin, a silicone-based resin, a urethane-based resin, an epoxy-based resin, a rubber-based resin, and a polyester-based resin, and may comprise one or more resins from the same resin family. The first adhesive layer AD1 and the second adhesive layer AD2 may have adhesive strength that varies depending on the rigidity and surface energy of the base resin.

[0093] Each of the protective film PF, the first adhesive layer AD1, and the second adhesive layer AD2 may comprise an optically transparent material. Therefore, in the configuration where the protective film PF is attached to the display module 100 and the first adhesive layer AD1 and the second adhesive layer AD2 are interposed therebetween, the image generated by the display module 100 can be transmitted to the outside of the display device 1000 through the first adhesive layer AD1, the second adhesive layer AD2, and the protective film PF.

[0094] The protection module 200 may be optically transparent at room temperature. As an example, the protection module 200 may have a haze value equal to or less than about 4% at room temperature. However, the haze value of the protection module 200 should not be limited to or restricted by this.

[0095] The adhesive strength of the first adhesive layer AD1 can decrease as the temperature increases from room temperature to a higher temperature (e.g., a temperature above room temperature). The adhesive strength of the first adhesive layer AD1 can vary significantly above a reference temperature. As an example, the first adhesive layer AD1 can have a first adhesive strength at room temperature and a second adhesive strength at a higher temperature, and the second adhesive strength can be reduced to about 50% or more compared to the first adhesive strength. Specifically, the first adhesive layer AD1 can have a first adhesive strength at a temperature of about 25 degrees Celsius and a second adhesive strength at a temperature of about 70 degrees Celsius, and the second adhesive strength can be less than half of the first adhesive strength.

[0096] The adhesive strength of the second adhesive layer AD2 can gradually decrease as the temperature increases from room temperature to higher temperatures, compared to the adhesive strength of the first adhesive layer AD1. The adhesive strength between the first adhesive layer AD1 and the window WP at room temperature can be substantially equal to or similar to the adhesive strength between the second adhesive layer AD2 and the window WP at room temperature. As an example, at room temperature, the adhesive strength between the first adhesive layer AD1 and the window WP, and the adhesive strength between the second adhesive layer AD2 and the window WP, can be equal to or greater than approximately 400 gf / inch.

[0097] However, the adhesive force between the first adhesive layer AD1 and the window WP at high temperatures can be less than the adhesive force between the second adhesive layer AD2 and the window WP at high temperatures. For example, at a temperature equal to or greater than 70 degrees Celsius, the second adhesive layer AD2 can have an adhesive force greater than that of the first adhesive layer AD1. As an example, the adhesive force between the second adhesive layer AD2 and the window WP at a temperature of about 80 degrees Celsius can be about 400 gf / inch, and the adhesive force between the first adhesive layer AD1 and the window WP at a temperature of about 80 degrees Celsius can be equal to or less than about 50 gf / inch.

[0098] Because the adhesive force of the first adhesive layer AD1 in contact with the window WP decreases significantly at the reference temperature, the protective film PF can be easily peeled off from the upper surface WP-U of the window WP at high temperatures. As an example, when the protective film PF needs to be replaced, heat can be applied to the protective film PF to easily peel it off from the display module 100, and damage to the display panel DP can be reduced or effectively prevented during the replacement process. That is, heating the protective film PF reduces the adhesive force of the first adhesive layer AD1 at the interface between the protective module 200 and the display module 100.

[0099] The first adhesive layer AD1 may include a side-chain crystalline polymer. The side-chain crystalline polymer may include a copolymer formed by the polymerization of one or more monomers. In embodiments, for example, the first adhesive layer AD1 may include at least one of a hexadecyl methacrylate copolymer, an octadecyl methacrylate copolymer, an eicosyl methacrylate copolymer, and a docosyl methacrylate copolymer. Because the first adhesive layer AD1 includes a side-chain crystalline polymer, the degree of variation in the adhesive strength of the first adhesive layer AD1 can increase at high temperatures.

[0100] The second adhesive layer AD2 can have a relatively small modulus. The modulus of the second adhesive layer AD2 can be smaller than that of the first adhesive layer AD1. As an example, the modulus of the second adhesive layer AD2 at -20 degrees Celsius can be equal to or less than about 0.2 MPa. Because the second adhesive layer AD2 has a relatively small modulus, the adhesive layer will not be damaged or deformed even if the display device 1000 is repeatedly folded and unfolded.

[0101] The thickness of each of the first adhesive layer AD1 and the second adhesive layer AD2 can affect folding reliability. Folding reliability can be improved by adjusting the thickness of the first adhesive layer AD1 and the second adhesive layer AD2. As an example, the first thickness D1 of the first adhesive layer AD1 can be equal to or greater than about 5 μm and equal to or less than about 25 μm. The second thickness D2 of the second adhesive layer AD2 can be equal to or greater than about 10 μm and equal to or less than about 100 μm. The first thickness D1 of the first adhesive layer AD1 can be less than the second thickness D2 of the second adhesive layer AD2 within the range described above; however, it should not be limited thereto or restricted by it.

[0102] Figure 6A It is a graph showing the relationship between temperature and adhesive force of the first adhesive layer AD1-a and the comparative adhesive layer AD'. Figure 6B This is a schematic diagram illustrating an embodiment of the molecular structure of the first adhesive layer.

[0103] Figure 6A This is a schematic diagram illustrating the adhesive force of the first adhesive layer AD1-a, corresponding to the first adhesive layer AD1 described above, as a function of temperature. The first adhesive layer AD1-a may comprise a side-chain crystalline polymer. Figure 6A The adhesive strength of a comparative adhesive layer AD' excluding the side-chain crystalline polymer, as a function of temperature, is also shown for comparison with the adhesive strength of the first adhesive layer AD1-a.

[0104] The first adhesive layer AD1-a can have a first adhesive force F1 at a first temperature T1. The first temperature T1 can be room temperature. Within a temperature range near the first temperature T1, the adhesive force of the first adhesive layer AD1-a can be substantially the same as the first adhesive force F1, or the difference between the adhesive force of the first adhesive layer AD1-a and the first adhesive force F1 can be very small. On the other hand, within a temperature range near the first temperature T1, the adhesive force of the comparative adhesive layer AD' can gradually decrease as the temperature increases. In an embodiment, for example, within a temperature range near the first temperature T1, the degree of decrease in the adhesive force of the comparative adhesive layer AD' can be greater than the degree of decrease in the adhesive force of the first adhesive layer AD1-a. When the first adhesive layer AD1-a maintains the first adhesive force F1 at room temperature, the protective film PF can be attached to the upper surface WP-U of the window WP (reference). Figure 5 It will not be peeled off even with repeated folding and unfolding operations.

[0105] Even with increased temperature, the adhesive strength of the first adhesive layer AD1-a can remain at a constant value, and then can significantly decrease above a reference temperature. The first adhesive layer AD1-a can have a second adhesive strength F2 at a second temperature T2, which is above the first temperature T1. The second temperature T2 can be higher than the temperature at which the first adhesive layer AD1-a melts. The second adhesive strength F2 can be equal to or less than half of the first adhesive strength F1. Because the adhesive strength of the first adhesive layer AD1-a decreases significantly at high temperatures, the protective film PF (reference) attached to the window WP by the first adhesive layer AD1-a in contact with the window WP... Figure 5 ) can be seen from the upper surface of window WP-U (reference) Figure 5 It can be easily peeled off.

[0106] Therefore, by applying heat to the protective film PF, the protective film PF can be easily removed from the upper surface WP-U of the window WP, and damage to the display panel DP can be reduced or effectively prevented during the replacement of the protective film PF within the display device 1000.

[0107] On the other hand, the comparative adhesive force F2' of the comparative adhesive layer AD' at the second temperature T2 can be greater than the second adhesive force F2. When the temperature rises from the first temperature T1 to the second temperature T2, the degree of decrease in the adhesive force of the first adhesive layer AD1-a can be greater than the degree of decrease in the adhesive force of the comparative adhesive layer AD'.

[0108] The first adhesive layer AD1-a can have a third adhesive force F3 at a third temperature T3, which is higher than the second temperature T2. As the temperature increases from the second temperature T2 to the third temperature T3, the decrease in adhesive force of the first adhesive layer AD1-a can be greater than the decrease in adhesive force of the comparative adhesive layer AD'. At the third temperature T3, the adhesive force of the first adhesive layer AD1-a can be less than the adhesive force of the comparative adhesive layer AD'. The third adhesive force F3 can be less than the first adhesive force F1 and the second adhesive force F2. As an example, the third temperature T3 can be equal to or greater than about 90 degrees Celsius, and the third adhesive force F3 can be equal to or less than about 10% of the first adhesive force F1.

[0109] Figure 6B The molecular structure of the first adhesive layer AD1-a at the first temperature T1 (graph AA) and the molecular structure of the first adhesive layer AD1-a at the second temperature T2 (graph BB) are schematically shown.

[0110] refer to Figure 6B The molecular structure of the first adhesive layer AD1-a at room temperature can have a crystalline structure in which side chains SC are vertically bonded between multiple main chains MC arranged parallel to each other. When the temperature increases due to heat (“thermal energy”), the molecules of the first adhesive layer AD1-a can have increased degrees of freedom and can easily entangle with each other. Therefore, as Figure 6B As shown in the figure BB, the side chains SC bonded between the main chain MC can entangle with each other, and therefore, the adhesive force of the first adhesive layer AD1-a can be reduced.

[0111] Table 1 below shows the results obtained by evaluating the reliability of the protective module 200 by measuring the thickness of each of the first adhesive layer AD1 and the second adhesive layer AD2 according to the embodiments and comparative examples. The reliability evaluation of the protective module 200 was performed by measuring the first adhesive force between the protective module 200 and the window WP at a temperature of approximately 25 degrees Celsius and the second adhesive force between the protective module 200 and the window WP at a temperature of approximately 80 degrees Celsius. Furthermore, the evaluation assessed whether the protective module 200 was peeled off during repeated folding and unfolding of the display device 1000 after each of the embodiment and comparative protective modules was applied to the display device 1000, whether the display panel DP was damaged when each corresponding protective film PF was replaced, and whether the adhesive layers were altered during the use of the display device 1000.

[0112] Table 1

[0113]

[0114]

[0115] In Table 1, "E1 to E6" correspond to Examples 1 to 6, respectively, and "C1 to C5" correspond to Comparative Examples 1 to 5. Examples and comparative examples may include... Figure 5 The components corresponding to the elements of the display device 1000 shown, in each of the embodiments and comparative examples, the first adhesive layer AD1 comprises a hexadecyl methacrylate copolymer, and the second adhesive layer AD2 in each of the embodiments and comparative examples comprises an acrylic resin. However, Comparative Example 4 does not include the component corresponding to the second adhesive layer AD2, and Comparative Example 5 does not include the component corresponding to the first adhesive layer AD1.

[0116] In Table 1, “D1” represents the first thickness of the first adhesive layer AD1, and “D2” represents the second thickness of the second adhesive layer AD2. “A1” represents the first adhesive force, and “A2” represents the second adhesive force. “FR” indicates whether the protective film PF was peeled off during the folding test. When FR is 1, this means that the protective film PF was not peeled off when the display device 1000 was repeatedly folded and unfolded 1000 times. When FR is less than 1 (FR<1), this means that the protective film PF was peeled off when the display device 1000 was repeatedly folded and unfolded less than 1000 times.

[0117] The first and second adhesive forces are measured by a 180-degree peel test, and the protective film PF is evaluated by visually observing the peeling of the protective film PF during repeated folding and unfolding of the display device 1000 (where the protective film PF is attached using an adhesive layer). The display panel DP is evaluated for damage during replacement of the protective module 200 by visually observing whether it is damaged when the protective film PF separates from the display module 100. The adhesive layer is evaluated for changes during use of the display device 1000 by visually observing whether it discolors or deforms after attaching the protective module 200.

[0118] In Examples 1 to 6, each thickness of the first adhesive layer AD1 is equal to or greater than about 5 μm and equal to or less than about 25 μm, and each thickness of the second adhesive layer AD2 is equal to or greater than about 10 μm and equal to or less than about 100 μm. In Examples 1 to 6, each first adhesive force is about 500 gf / inch, and each second adhesive force is equal to or less than about 50 gf / inch. Specifically, in Example 3, the thickness of the first adhesive layer is about 25 μm, the second adhesive force is about 20 gf / inch, and the adhesive force decreases significantly at high temperatures.

[0119] In Examples 1, 5, and 6, even if the display device 1000 is repeatedly folded and unfolded 200,000 times, the protective film PF will not be peeled off or damaged. In Examples 2 to 4, even if the display device 1000 is repeatedly folded and unfolded 100,000 times, the protective film PF will not be peeled off or damaged.

[0120] There are some differences in the thickness of each of the first adhesive layer and the second adhesive layer in Comparative Examples 1 to 3 and the Embodiment. In Comparative Example 1, the thickness of the first adhesive layer AD1 is more than about 25 μm but less than about 30 μm, and the protective film PF is peeled off after fewer than 10,000 repeated folding and unfolding operations. In Comparative Example 2, the thickness of the second adhesive layer AD2 is less than about 10 μm but less than about 8 μm, and the protective film PF is peeled off after fewer than 10,000 repeated folding and unfolding operations. In Comparative Example 3, the thickness of the second adhesive layer AD2 is more than about 100 μm but less than about 120 μm, and the protective film PF is peeled off after fewer than 1,000 repeated folding and unfolding operations. Therefore, when the thickness of each of the first adhesive layer AD1 and the second adhesive layer AD2 is not within a certain range, the folding reliability of the display device 1000 may be reduced.

[0121] In Comparative Example 4, which does not include the second adhesive layer AD2, the protective film PF peels off after fewer than 1000 folding and unfolding operations. Without the second adhesive layer AD2, the modulus of the adhesive layer can be greater than that of the adhesive layer in the embodiment. Therefore, when a protective module 200 including an adhesive layer with a relatively high modulus is applied to the display device 1000, folding reliability may be reduced.

[0122] The second adhesive force of Comparative Example 5, excluding the first adhesive layer AD1, is approximately 400 gf / inch. Without the first adhesive layer AD1, the adhesive layer can maintain a relatively large adhesive force at high temperatures. Therefore, although the folding and unfolding operation was repeated 200,000 times, folding reliability was maintained in Comparative Example 5, but the display panel DP was damaged when the protective film PF was separated. This is because the protective film PF is difficult to separate due to the high adhesive force of the adhesive layer used to attach the protective film PF to the display module 100.

[0123] In this embodiment, even if the protective film PF separates from the display module 100, the display panel DP will not be damaged, and the adhesive layer will not discolor or deform. Furthermore, the folding reliability is improved in this embodiment compared to the folding reliability in the comparative example.

[0124] When the adhesive force between the adhesive layer and the display module 100 is low, it has the advantage that the protective film PF can be easily removed from the display module 100 when it is replaced. However, it has the disadvantage that the protective film PF may be easily peeled off due to repeated folding and unfolding operations. When the adhesive force between the adhesive layer and the display module 100 is high, it has the advantage that the protective film PF will not easily peel off even if the display device 1000 is repeatedly folded and unfolded. However, it has the disadvantage that the display module 100 may be damaged when the protective film PF is replaced. Therefore, it is necessary to control the adhesive force of the adhesive layer, and the adhesive layer of this disclosure can be prevented from being easily peeled off from the display module 100 at room temperature, can have improved folding reliability, and can be easily removed from the display module 100 at high temperatures.

[0125] Figures 7A to 7C This is a cross-sectional view showing an embodiment of the display device 1000. Apart from some components, Figures 7A to 7C The display device 1000 shown includes elements that are substantially the same as those in the embodiments described above. Hereinafter, features that differ from those in the embodiments described above will be primarily described.

[0126] At least one of the adhesive layers AD1 and AD2 may also include a foaming agent, such as a first foaming agent FF1 and / or a second foaming agent FF2. Figure 7A The protective module 200-1 shown may include a first adhesive layer AD1 containing a first foaming agent FF1. Figure 7B The protective module 200-2 shown may include a second adhesive layer AD2 containing a second foaming agent FF2. Figure 7C The protection module 200-3 shown may include a first adhesive layer AD1 and a second adhesive layer AD2, which respectively include a first foaming agent FF1 and a second foaming agent FF2.

[0127] Blowing agents FF1 and FF2 can be materials whose volume increases when their temperature rises or when they are exposed to ultraviolet (UV) light. As an example, blowing agents FF1 and FF2 may include a core portion containing an adhesive control agent and an outer portion surrounding the core portion. The adhesive control agent can evaporate under conditions of heat or UV light, and therefore, the volume of blowing agents FF1 and FF2 can increase. As the volume of blowing agents FF1 and FF2 increases, the adhesive strength of the adhesive layer including blowing agents FF1 and FF2 can decrease.

[0128] Blowing agents FF1 and FF2 can be dispersed in a polymer resin included in a first adhesive layer AD1 and a second adhesive layer AD2. Blowing agents included in the same adhesive layer can have substantially the same size as each other; however, this should not be a limitation or constraint. According to embodiments, blowing agents FF1 and FF2 can have different sizes than each other. However, blowing agents FF1 and FF2 can have a spherical shape; this should not be a limitation or constraint.

[0129] According to the implementation method, foaming agents FF1 and FF2 can have an elliptical shape.

[0130] Under heat or UV irradiation conditions, the protective film PF can be easily separated from the display module 100 due to the adhesive layers AD1 and AD2, which include foaming agents FF1 and FF2, and the protective film PF can be replaced without damaging the display panel DP. However, when the content of foaming agents FF1 and FF2 included in the adhesive layers AD1 and AD2 is high, the thickness of the corresponding adhesive layer may increase, and the modulus of the corresponding adhesive layer may increase. Therefore, when the content of foaming agents FF1 and FF2 is too high, the folding reliability of the display device 1000 may decrease.

[0131] As an example, the content of each of the foaming agents FF1 and FF2 in the respective adhesive layer may be equal to or less than about 3%. Specifically, based on the total content (100%) of the material included in the first adhesive layer AD1, the content of the first foaming agent FF1 included in the first adhesive layer AD1 may be equal to or less than about 3%. Based on the total content of the material included in the second adhesive layer AD2, the content of the second foaming agent FF2 included in the second adhesive layer AD2 may be equal to or less than about 3%.

[0132] Figure 8A and Figure 8B This is a cross-sectional view showing an embodiment of the display device 1000a. Figure 8A and Figure 8B This is a cross-sectional view showing the display device 1000a fully folded (fully inwardly folded). The above description can be applied to the components of the display device 1000a. Except for some components of the support module 300, respectively... Figure 8A and Figure 8B The display device 1000a shown may include substantially the same components, and the different features of the display device 1000a will be described in detail below.

[0133] refer to Figure 8AThe display device 1000a may include a support plate 320, and the support plate 320 may include a plurality of support members 321a and 322a. The support members 321a and 322a may include a first support member 321a that overlaps with a first non-folded region NFA1 and a second support member 322a that overlaps with a second non-folded region NFA2.

[0134] The unfolded display device 1000a can have a first support member 321a and a second support member 322a spaced apart from each other in a first direction DR1 at the folded region FA. That is, the support plate 320 can be disconnected at the folded region FA. The first support member 321a and the second support member 322a can be spaced apart from each other in the region overlapping with the folded region FA. The first support member 321a can support the rear surface of the display module 100 that overlaps with the first non-folded region NFA1, and the second support member 322a can support the rear surface of the display module 100 that overlaps with the second non-folded region NFA2.

[0135] In the fully inward-folding display device 1000a, the rear surfaces of the first support member 321a and the second support member 322a can face opposite directions. The support plate 320 may include support members 321a and 322a spaced apart from each other, and therefore, when the display device 1000a is folded, the support plate 320 may not be folded to have curvature in the folding region FA. That is, in the folded display device 1000a, each of the support members 321a and 322a can support the display module 100 while remaining flat, and may not be curved or deformed in the folding region FA.

[0136] refer to Figure 8B The display device 1000a may include a support plate 320 having a solid plate shape. The support plate 320 may include a first portion 321b overlapping the first non-folded region NFA1, a second portion 322b overlapping the second non-folded region NFA2, and a third portion 323b overlapping the folded region FA.

[0137] The support plate 320 may be provided with a plurality of openings OP defined in a third portion 323b overlapping the folded area FA. The openings OP may be defined to extend through the support plate 320. The openings OP may be arranged spaced apart from each other in one direction. As an example, the openings OP may be arranged in a matrix shape or a zigzag shape within the third portion 323b, and the arrangement of the openings OP should not be particularly limited. The solid portion of the support plate 320 may alternate with the openings OP to define the third portion 323b, but is not limited thereto.

[0138] Although not shown in the figures, the opening OP can be configured to be recessed from the upper surface of the support plate 320 but not penetrate the groove of the support plate 320. The upper surface of the support plate 320 can be closest to the display module 100, but is not limited thereto. Therefore, the thickness of the support plate 320 at a portion of the third portion 323b of the support plate 320 can be less than the thickness of the support plate 320 at the first portion 321b and the second portion 322b.

[0139] The unfolded display device 1000a can define the original size of the opening OP. Due to the tensile force in the folded display device 1000a, the folded display device 1000a can define the opening OP to be larger than the original size. The support plate 320 can be provided with an opening OP defined to overlap with the folding area FA, thereby improving the flexibility of the support plate 320.

[0140] Figures 9A to 9D This is a perspective view showing an embodiment of the display device 1000' or 1000. Figures 9A to 9D This is a perspective view showing an embodiment of the replacement process of the damaged protective film PF' of the protection module 200.

[0141] Figure 9A A display device 1000' is shown, including a damage protection module 200' (which includes a damage protection film PF'). The damage protection film PF' of the display device 1000' may be damaged due to external impact or repeated folding and unfolding operations. The damage protection film PF' may need to be replaced.

[0142] refer to Figure 9B A heat supply device 10 can be positioned above the display device 1000' to replace the damaged protective film PF'. The heat supply device 10 can provide heat HT to the display device 1000'. Due to the heat HT, the crystalline phase of the first adhesive layer AD1 can be altered. As an example, such as... Figure 6B As shown, the molecular structure of the first adhesive layer AD1 can be altered by heat HT. Therefore, as described above, the adhesive strength of the first adhesive layer AD1 at high temperatures can be significantly reduced compared to its adhesive strength at room temperature.

[0143] Figure 9C The process of separating the damaged protective film PF' to be replaced from the upper surface WP-U of the window WP after applying heat HT is illustrated. The adhesive force of the first adhesive layer AD1 used to attach the damaged protective film PF' to the upper surface WP-U of the window WP can be reduced by the heat HT, and therefore, the damaged protective film PF' can be easily separated from the window WP. Thus, when replacing the damaged protective film PF', damage to the display panel DP can be reduced or effectively prevented.

[0144] Specifically, the first adhesive force can act between the rear surface AD1-B of the first adhesive layer AD1 and the upper surface WP-U of the window WP at room temperature, and the second adhesive force can act between the rear surface AD1-B of the first adhesive layer AD1 and the upper surface WP-U of the window WP at a high temperature. By applying heat HT, the second adhesive force can be reduced to about 50% or more compared to the first adhesive force. In an embodiment, for example, the first adhesive force can be about 500 gf / inch at a temperature of about 25 degrees Celsius, and the second adhesive force can be about 50 gf / inch at a temperature of about 80 degrees Celsius.

[0145] Figure 9D A repaired display device 1000 including an undamaged protection module 200-N is shown. The undamaged protection module 200-N may include an undamaged protective film PF-N, a second adhesive layer AD2-N disposed on the rear surface of the undamaged protective film PF-N, and a first adhesive layer AD1-N disposed on the rear surface of the second adhesive layer AD2-N. The undamaged protection module 200-N can be attached to the display module 100 such that the first adhesive layer AD1-N is attached to the upper surface WP-U of the window WP (see [reference]). Figure 9C )touch.

[0146] The adhesive force of the first adhesive layer AD1-N at room temperature is greater than that at high temperatures, and the undamaged protective film PF-N is not easily peeled off from the window WP. That is, even if the display device 1000 is repeatedly folded and unfolded, the undamaged protective film PF-N is not easily peeled off. Furthermore, although the display device 1000 is repeatedly folded and unfolded, folding reliability can be maintained by the second adhesive layer AD2-N, which has a relatively small modulus.

[0147] The display device 1000 may include a protective film PF and an adhesive layer disposed beneath the protective film PF. The adhesive layer may include an adhesive layer having a relatively small modulus and an adhesive layer having a high degree of variability in adhesion at high temperatures. Even if the display device 1000 is repeatedly folded and unfolded, the folding reliability of the display device 1000 will not be reduced through the adhesive layer, and the protective film PF can be easily peeled off from the display module 100. Furthermore, the protective film PF can be easily removed from the display module 100 through the adhesive layer at high temperatures, and the protective film PF can be replaced without damaging the display module 100.

[0148] Although embodiments of the present disclosure have been described, it should be understood that the present disclosure is not limited to these embodiments, but rather various changes and modifications can be made by those skilled in the art as to the spirit and scope of the present disclosure as claimed herein.

[0149] Therefore, the subject matter disclosed herein should not be limited to any single embodiment described herein, and the scope of the invention should be determined in accordance with the appended claims.

Claims

1. A display device, comprising: The display panel is foldable about a folding axis extending in the first direction; Window, facing the display panel; A protective film faces the display panel, and the window is located between the protective film and the display panel; as well as Multiple adhesive layers, situated between the window and the protective film and connecting the window to the protective film, wherein the multiple adhesive layers, from the window to the protective film, sequentially comprise: The first adhesive layer comprises a side-chain crystalline polymer and a modulus; as well as The second adhesive layer faces the first adhesive layer and has a modulus smaller than that of the first adhesive layer. The first adhesive layer has a first adhesive force at room temperature and a second adhesive force at a temperature equal to or higher than a reference temperature, wherein the reference temperature is higher than room temperature. The second adhesive force is equal to or less than 50% of the first adhesive force.

2. The display device according to claim 1, wherein, The reference temperature is 70 degrees Celsius.

3. The display device according to claim 2, wherein, At a temperature equal to or greater than 70 degrees Celsius, the second adhesive layer has an adhesive force greater than the second adhesive force of the first adhesive layer.

4. The display device according to claim 1, wherein, The side-chain crystalline polymer includes at least one of (meth)acrylic acid hexadecyl ester copolymer, (meth)acrylic acid octadecyl ester copolymer, (meth)acrylic acid eicosyl ester copolymer, and (meth)acrylic acid dodecyl ester copolymer.

5. The display device according to claim 1, wherein, In the first adhesive layer and the second adhesive layer sequentially disposed from the window to the protective film: Each of the first adhesive layer and the second adhesive layer has a thickness, and The thickness of the first adhesive layer is less than the thickness of the second adhesive layer.

6. The display device according to claim 1, wherein, At least one of the first adhesive layer and the second adhesive layer further includes a foaming agent.

7. The display device according to claim 6, wherein, In the first adhesive layer and the second adhesive layer sequentially disposed from the window to the protective film: The foaming agent included in the first adhesive layer has a content of 3% or less based on the total content.

8. A display device, comprising: The display panel can be folded around the folding axis; Window, facing the display panel; A protective film faces the display panel, and the window is located between the protective film and the display panel; as well as A plurality of adhesive layers, situated between the window and the protective film and connecting the window to the protective film, wherein the plurality of adhesive layers between the window and the protective film sequentially comprise: A first adhesive layer having a first adhesive force at room temperature and a second adhesive force at a temperature equal to or greater than 70 degrees Celsius; and The second adhesive layer is in contact with the first adhesive layer and has a third adhesive force at a temperature equal to or greater than 70 degrees Celsius. in, The second adhesive force of the first adhesive layer is less than the third adhesive force of the second adhesive layer, and The second adhesive force of the first adhesive layer is equal to or less than 50% of the first adhesive force of the first adhesive layer.

9. The display device according to claim 8, wherein, In the first adhesive layer and the second adhesive layer sequentially disposed from the window to the protective film: Each of the first adhesive layer and the second adhesive layer has a thickness. The thickness of the first adhesive layer is equal to or greater than 5 micrometers and equal to or less than 25 micrometers, and The thickness of the second adhesive layer is equal to or greater than 10 micrometers and equal to or less than 100 micrometers.

10. The display device according to claim 8, wherein, In the first adhesive layer and the second adhesive layer sequentially disposed from the window to the protective film, the first adhesive layer comprises a side-chain crystalline polymer.

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