Display device

Abstract

The present disclosure relates to a display device comprising a display panel, a protective layer positioned on the display panel, and a first adhesive layer positioned between the display panel and the protective layer, wherein the first adhesive layer comprises 0.05 w% to 1 w% of a silane coupling agent, and the first adhesive layer has a creep of 20% or less at 60°C.

Description

Technology Field

[0001] The present disclosure relates to a display device, and more specifically, to a display device comprising an adhesive layer containing a silane coupling agent. Background Technology

[0002] With the recent advancement of display-related technologies, display devices capable of deformation during use—such as folding, rolling, or stretching like a rubber band—are being researched and developed. Because these displays can be transformed into various forms, they can satisfy both the demand for larger displays during use and the demand for smaller displays for portability.

[0003] When the display device is folded, a large amount of stress is concentrated at the folded part, and consequently, the components of the display device may lift or break in that area. In addition, during the manufacturing process of the display device, components such as the adhesive layer of the display device may be pressed or dented. The problem to be solved

[0004] The embodiments are intended to provide a display device comprising an adhesive layer having low creep and high reliability at high temperatures. means of solving the problem

[0005] A display device according to one embodiment includes a display panel, a protective layer located on the display panel, and a first adhesive layer located between the display panel and the protective layer, wherein the first adhesive layer contains 0.05 w% to 1 w% of a silane coupling agent, and the first adhesive layer has a creep of 20% or less at 60°C.

[0006] The above silane coupling agent may be a compound represented by the following chemical formula 1.

[0007] [Chemical Formula 1]

[0008] R'-Si-(OR)3

[0009] The above R' may be one of alkyl, vinyl, carboxyl, glycidoxyl, epoxy, glycidyl, amino, mercapto, acrylic, methacrylic, primary amine, secondary amine, tertiary amine, and quaternary amine having 1 to 10 carbon atoms, and the above R may be one of hydrogen, alkyl, aryl, alkylaryl, arylalkyl, alkenyl, cycloalkenyl, alken, alkylene, arylene, alkylarylene, arylalkylene, and cycloalkylene having 1 to 10 carbon atoms.

[0010] The thickness of the first adhesive layer may be 25 μm to 100 μm.

[0011] The above display panel further includes a display layer, a window, and a hard coating layer, and the hard coating layer and the first adhesive layer can be in direct contact.

[0012] It further includes a second adhesive layer located between the display layer and the window, and the composition of the second adhesive layer and the first adhesive layer may be different.

[0013] The first adhesive layer may be located at the top of a plurality of adhesive layers included in the display device.

[0014] The first adhesive layer above may be a PSA (pressure sensitive adhesive).

[0015] The above window comprises polyimide, and the first adhesive layer may have a peel strength of 500 gf / in or more at room temperature (25°C) for the window.

[0016] The first adhesive layer may have a peel strength of 514 gf / in to 574 gf / in at room temperature (25℃) for the window.

[0017] The above window comprises polyimide, and the first adhesive layer may have a peel strength of 300 gf / in or less at 60°C for the window.

[0018] The first adhesive layer may have a peel strength of 267 gf / in to 287 gf / in for the window at 60°C.

[0019] The first adhesive layer may have a storage modulus of 0.02 MPa to 0.035 MPa at 60°C.

[0020] The glass transition temperature of the first adhesive layer above may be -30 ℃ or lower.

[0021] The first adhesive layer above may be a double-sided adhesive layer.

[0022] The above display device may be foldable.

[0023] The radius of curvature of the above-mentioned foldable display device may be 1.5R or greater.

[0024] It may further include a polarizing layer located between the display layer and the window, a third adhesive layer located between the display layer and the polarizing layer, a film layer located on the other side of the display layer, and a fourth adhesive layer located between the display layer and the film layer.

[0025] The composition of the third adhesive layer and the fourth adhesive layer may differ from the composition of the first adhesive layer.

[0026] The invention further includes a cushion layer located on the other side of the display panel and a fifth adhesive layer for attaching the cushion layer and the display panel, wherein the composition of the fifth adhesive layer and the composition of the first adhesive layer may be different.

[0027] A display device according to another embodiment includes a display panel, a protective layer located on the display panel, and a first adhesive layer located between the display panel and the protective layer, wherein the first adhesive layer comprises 0.05 w% to 1 w% of a compound represented by the following chemical formula 1, and the first adhesive layer may have a creep of 20% or less at 60°C.

[0028] [Chemical Formula 1]

[0029] R'-Si-(OR)3

[0030] The above R' may be one of alkyl, vinyl, carboxyl, glycidoxyl, epoxy, glycidyl, amino, mercapto, acrylic, methacrylic, primary amine, secondary amine, tertiary amine, and quaternary amine having 1 to 10 carbon atoms, and the above R may be one of hydrogen, alkyl, aryl, alkylaryl, arylalkyl, alkenyl, cycloalkenyl, alken, alkylene, arylene, alkylarylene, arylalkylene, and cycloalkylene having 1 to 10 carbon atoms. Effects of the invention

[0031] According to the embodiments, a display device comprising an adhesive layer having low creep and high reliability at high temperatures is provided. Brief explanation of the drawing

[0032] FIG. 1 briefly illustrates a cross-section of a display device according to one embodiment. Figure 2 briefly illustrates the process of an SCA compound according to the present embodiment combining with an inorganic material. Figure 3 illustrates the rework process of removing the protective layer again. FIG. 4 illustrates a display device according to the present embodiment. FIG. 5 is a schematic cross-sectional view of a display device according to one embodiment. Specific details for implementing the invention

[0033] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0034] To clearly explain the present invention, parts unrelated to the explanation have been omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0035] Furthermore, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and thus the present invention is not necessarily limited to what is illustrated. Thicknesses have been enlarged in the drawings to clearly represent various layers and regions. Additionally, for convenience of explanation, the thickness of some layers and regions has been exaggerated in the drawings.

[0036] Furthermore, when it is said that a part, such as a layer, membrane, region, or plate, is "on" or "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when it is said that a part is "directly above" another part, it means that there is no other part in between. Also, saying that a part is "on" or "on" a reference part means that it is located above or below the reference part, and does not necessarily mean that it is located "on" or "on" in the direction opposite to gravity.

[0037] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0038] Additionally, throughout the specification, "planar" means when the subject part is viewed from above, and "cross-sectional" means when the cross-section obtained by vertically cutting the subject part is viewed from the side.

[0039] Then, a display device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0040] FIG. 1 briefly illustrates a cross-section of a display device according to one embodiment. Referring to FIG. 1, the display device according to the present embodiment includes a display panel (100) and a protective layer (300) attached to the display panel (100), and the protective layer (300) and the display panel (100) are attached by a first adhesive layer (710).

[0041] At this time, the first adhesive layer (710) may be a pressure-sensitive adhesive (PSA). The first adhesive layer (710) may be a double-sided adhesive and may be used as the top layer in the module structure of a display device. The first adhesive layer (710) according to the present embodiment may have high peel strength at high temperature and high humidity and low creep. Creep refers to deformation that occurs over a specific period of time when a material is subjected to a constant stress under a constant temperature, and high creep means that there is a large amount of deformation at the same stress.

[0042] The first adhesive layer (710) may include at least one of polyurethane-based, polyacrylic-based, polyester-based, polyepoxy-based, and polyvinyl acetate-based materials.

[0043] The first adhesive layer (710) according to the present embodiment may have a creep of 20% or less at 60°C. Additionally, the peel strength of the first adhesive layer (710) according to the present embodiment for a window containing polyimide may be 500 gf / in or more at room temperature (25°C) and 300 gf / in or less at 60°C. Specifically, the peel strength of the first adhesive layer (710) according to the present embodiment for a window containing polyimide may be 514 gf / in to 574 gf / in at room temperature (25°C) and 267 gf / in to 287 gf / in at 60°C. Additionally, the peel strength at 60°C and 93% humidity may be 230 gf / in to 260 gf / in.

[0044] The thickness of the first adhesive layer (710) may be 25 μm to 100 μm.

[0045] The storage modulus of the first adhesive layer (710) at 60°C may be 0.02 MPa to 0.035 MPa. Thus, it can relieve stress on other adjacent layers.

[0046] In addition, the glass transition temperature of the first adhesive layer (710) may be -30 ℃ or lower. Therefore, bending can occur easily even at low temperatures.

[0047] The first adhesive layer (710) may include a silane coupling agent (SCA). The silane coupling agent is a compound that has two or more different reactive groups within a molecule to form a chemical bond between an organic material and an inorganic material. It consists of a reactive group (OR) that forms a chemical bond with the inorganic material and an organic functional group (R) that forms a bond with the polymer, and acts as a bridge connecting the organic material and the inorganic material.

[0048] The silane coupling agent may include a compound represented by the following chemical formula 1.

[0049] [Chemical Formula 1]

[0050] R'-Si-(OR)3

[0051] In the above chemical formula 1, R' may be an alkyl group having 1 to 10 carbon atoms. Specifically, R' may be selected from the group consisting of methyl, ethyl, vinyl, carboxyl, glycidoxyl, epoxy, glycidyl, amino, mercapto, acrylic, and methacrylic groups. R may include a nitrogen atom and may be, for example, an amine group. The amine group may be a primary, secondary, tertiary, or quaternary group.

[0052] In the above chemical formula 1, R may be one of hydrogen, alkyl, aryl, alkylaryl, arylalkyl, alkenyl, cycloalkenyl, alken, alkylene, arylene, alkylarylene, arylalkylene, and cycloalkylene having 1 to 10 carbon atoms. Specifically, R may be hydrogen and a linear or branched C1 to C6 alkyl group.

[0053] In the above chemical formula 1, R' can bond with organic materials, and OR can chemically bond with inorganic materials.

[0054] The compound of Formula 1 is included in the first adhesive layer (710), thereby improving the peel strength of the first adhesive layer (710) having low creep in high temperature and high humidity environments. Thus, reliability can be ensured when folding the display device.

[0055] FIG. 2 briefly illustrates the process of the compound of Formula 1 according to the present embodiment being bonded with an inorganic material. As shown in FIG. 2, the compound according to the present embodiment can be bonded with an inorganic material through hydrolysis and condensation reactions. As shown in FIG. 2, the compound of Formula 1 according to the present embodiment can be bonded with a window (UTG) and can increase the peel strength between the window (UTG) and the first adhesive layer (710).

[0056] In this embodiment, the content of the silane coupling agent included in the first adhesive layer (710) may be 0.05 w% to 1 w%. Specifically, the content of the compound of Formula 1 may be 0.05 w% to 1 w%. If the content of the compound of Formula 1 is 0.05 w% or less, it may not have a sufficient peel strength enhancement effect, and if the content of the compound of Formula 1 is 1 w% or more, the release property may increase and the adhesive strength may decrease.

[0057] As described above, the display device according to the present embodiment has a first adhesive layer (710) located at the top of the display device that includes a compound represented by Chemical Formula 1, and has low creep (creep of 20% or less at 60°C) and high peel strength at high temperatures (300 gf / in or less at 60°C). Therefore, it is easy to handle during the manufacturing process and can have high reliability in the usage environment.

[0058] If the protective layer (300) is incorrectly attached during the attachment process of the display panel (100), a rework process is required to remove it again. FIG. 3 illustrates the rework process of removing the protective layer (300). Therefore, the first adhesive layer (710) used for attaching the protective layer (300) requires characteristics that have low peel strength at high temperatures and good reliability in high temperature and high humidity environments. In addition, since the display device according to the present embodiment is a foldable display device, an adhesive with low modulus and high creep has been used to ensure reliability when folded. However, using such an adhesive with high creep is unsuitable because the first adhesive layer (710) may be scratched or pushed due to external impact during the manufacturing process. Furthermore, because the peel strength at high temperatures is low, there was a problem of peeling when the temperature increased during the use of the display device.

[0059] However, in the case of the display device according to the present embodiment, the first adhesive layer (710) includes a compound represented by Chemical Formula 1, thereby improving the peel strength in high temperature and high humidity environments and reducing creep. Therefore, defects such as indentation and squeezing can be reduced during the manufacturing process, and reliability in the usage environment is improved as the peel strength in high temperature and high humidity environments is improved.

[0060] Table 1 shows the results of measuring individual reliability and surface indentation characteristics for various examples and comparative examples with different creep and peel strengths of the first adhesive layer (710).

[0061] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thickness (㎛) 35 35 35 35 Crepp (%) 60°C <20% 95 ±10 40 ±10 <20% PI Window Peel Strength (gf / In) RT (25°C) 544 ±30 355 ±7 315 ±8 447 ±6 60°C(10 min) 277 ±10 130 ±5 104 ±16 157 ±8 60°C (humidity 93%) 245 ±15 88 ±11 96 ±3 140 ±8 Unit Reliability (THB Folding) 60°C / 93% THB: 150K cycles OK NG(3F / 3) Buckling & Cohesion Breakdown NG(1F / 3)Buckling NG(3F / 3)Buckling Surface Indentation Characteristics* Indentation depth under 500 gf load with identical 700 µm lamination 7 ㎛ 23 ㎛ 15 ㎛ 7.5 ㎛

[0062] The individual reliability test was conducted by performing 150,000 folds and unfolds on the structure of the display panel / adhesive / polyimide window under conditions of 60°C and 93% humidity. As can be seen from Table 1 above, Example 1 passed the reliability test because it had low creep of 20% or less and high peel strength at high temperature and high humidity, and the indentation also showed the lowest value.

[0063] In the case of Comparative Example 1, since the creep was high at over 90% and the high temperature and high humidity peeling strength was low, buckling and cohesion failure phenomena occurred during the reliability test.

[0064] Likewise, in the case of Comparative Example 2, although the creep level was 45%, which is more than half lower than that of Comparative Example 1, the peel strength at high temperature and high humidity was low, so a buckling phenomenon occurred during the reliability test.

[0065] In the case of Comparative Example 3, the creep was at a level similar to Example 1, but because the peel strength at high temperature and high humidity was low, a buckling phenomenon occurred during the reliability test.

[0066] That is, as in Example 1, it was confirmed that an adhesive having a creep level below a certain value and a peel strength above a certain value improves surface indentation characteristics while maintaining high reliability.

[0067] FIG. 4 illustrates a display device according to the present embodiment. Referring to FIG. 4, the display device according to the present embodiment may be a foldable display device. As shown in FIG. 4, the protective layer (300) and the first adhesive layer (710) are located on the top layer and are subjected to the most bending, and may be most vulnerable to stress in the bending portion. However, the display device according to the present embodiment has excellent reliability in the bending portion because it includes a first adhesive layer (710) having low creep and high peel strength. That is, the display device including the first adhesive layer according to the present embodiment is suitable for application to a foldable display device. Specifically, the first adhesive layer according to the present embodiment can be applied to a foldable display device having a radius of curvature of 1.5R or more, and can be applied to both In Folding and Out Folding.

[0068] Then, the specific stacking structure of the display device according to the present embodiment will be described in more detail below with reference to FIG. 5. FIG. 5 is a schematic cross-sectional view of a display device according to one embodiment.

[0069] Referring to FIG. 5, the display device according to the present embodiment includes a display panel (100), a support member (200) located below the display panel (100), and a protective layer (300) located above the display panel (100). For convenience of explanation, the display panel (100), the support member (200), and the protective layer (300) are depicted as being separated from each other, but in reality, they may be in contact with each other and connected as one.

[0070] Referring to FIG. 5, the protective layer (300) and the display panel (100) can be attached through the first adhesive layer (710). The description of the first adhesive layer (710) is the same as described above and is therefore omitted. The thickness of the protective layer (300) may be 45 μm to 65 μm.

[0071] The display panel (100) may include a film layer (110), a display layer (120), a polarizing layer (130), a window (140), and a hard coating layer (150), and may include a plurality of adhesive layers located between each layer. The laminated structure of the display panel (100) is merely an example, and some structures may be omitted depending on the embodiment. For example, the polarizing layer (130) may be omitted.

[0072] The film layer (110) and the display layer (120) can be attached with a fourth adhesive layer (740). At this time, the thickness of the fourth adhesive layer (740) may be 5 μm to 15 μm. The fourth adhesive layer (740) may have a different composition and characteristics from the first adhesive layer (710). That is, the first adhesive layer (710) contains a compound represented by Chemical Formula 1 and has low creep characteristics and high peel strength, but the fourth adhesive layer (740) does not contain a compound represented by Chemical Formula 1 and may have creep characteristics and peel strength different from the first adhesive layer (710).

[0073] The display layer (120) may be a layer on which transistors and light-emitting elements connected thereto are located to substantially display an image. The thickness of the display layer (120) may be 30 μm to 40 μm.

[0074] The display layer (120) and the polarization layer (130) are bonded together by a third adhesive layer (730). The thickness of the third adhesive layer (730) may be 40 μm to 60 μm. The third adhesive layer (730) may have a different composition and characteristics from the first adhesive layer (710). That is, the first adhesive layer (710) contains a compound represented by Chemical Formula 1 and has low creep characteristics and high peel strength, but the second adhesive layer (720) does not contain a compound represented by Chemical Formula 1 and may have creep characteristics and peel strength different from the first adhesive layer (710).

[0075] The thickness of the polarization layer (130) may be 20 μm to 40 μm. The polarization layer (130) may be omitted depending on the embodiment.

[0076] The polarizing layer (130) and the window (140) are bonded together by a second adhesive layer (720). The thickness of the fourth adhesive layer (720) may be 40 μm to 60 μm. The second adhesive layer (720) may have a different composition and characteristics from the first adhesive layer (710). That is, the first adhesive layer (710) contains a compound represented by Chemical Formula 1 and has low creep characteristics and high peel strength, but the second adhesive layer (720) does not contain a compound represented by Chemical Formula 1 and may have creep characteristics and peel strength different from the first adhesive layer (710).

[0077] A hard coating layer (150) may be positioned on the window (140). The hard coating layer (150) may include an acrylic material. The thickness of the hard coating layer (150) may be 5 μm to 15 μm.

[0078] The support member (200) includes a cushion layer (210) and a fifth adhesive layer (750) and a sixth adhesive layer (760) located on both sides of the cushion layer (210). The cushion layer (210) may include polyurethane foam. The thickness of the cushion layer (210) may be 70 μm to 90 μm.

[0079] The cushion layer (210) and the film layer (110) can be attached through the fifth adhesive layer (750). The thickness of the fifth adhesive layer (750) may be 20 μm to 30 μm. The fifth adhesive layer (750) may have a different composition and characteristics from the first adhesive layer (710). That is, the first adhesive layer (710) contains a compound represented by Chemical Formula 1 and has low creep characteristics and high peel strength, but the fifth adhesive layer (750) does not contain a compound represented by Chemical Formula 1 and may have creep characteristics and peel strength different from the first adhesive layer (710).

[0080] The thickness of the sixth adhesive layer (760) may be 20 μm to 30 μm. The sixth adhesive layer (760) may have a different composition and characteristics from the first adhesive layer (710). That is, the first adhesive layer (710) contains a compound represented by Chemical Formula 1 and has low creep characteristics and high peel strength, but the sixth adhesive layer (760) does not contain a compound represented by Chemical Formula 1 and may have creep characteristics and peel strength different from the first adhesive layer (710).

[0082] As described above, the display device according to the present embodiment includes an adhesive layer located on the top layer of the display device that comprises a silane coupling agent represented by Chemical Formula 1, thereby having low creep characteristics and high peel strength. Therefore, indentation defects that occurred when creep was high during the manufacturing process can be minimized, and reliability can be ensured in the usage environment due to the high peel strength. In particular, the display panel and the protective layer can be stably bonded in the folding portion of the foldable display device.

[0084] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0086] 100: Display panel 110: Film layer 120: Display layer 130: Polarizing layer 140: Windows 200: Jijibu 210: Cushion layer 300: Protective layer 710: 1st adhesive layer 720: 2nd adhesive layer 730: 3rd adhesive layer 740: 4th adhesive layer 750: 5th adhesive layer 760: 6th adhesive layer

Claims

Claim 1 A display device comprising: a display panel; a protective layer positioned on the display panel; and a first adhesive layer positioned between the display panel and the protective layer, wherein the first adhesive layer comprises 0.05 w% to 1 w% of a silane coupling agent, the first adhesive layer has a creep of 20% or less at 60°C, and the silane coupling agent is a compound represented by the following chemical formula 1: [Chemical Formula 1] R'-Si-(OR)3, wherein R' may be one of alkyl, vinyl, carboxyl, glycidoxyl, epoxy, glycidyl, amino, mercapto, acrylic, methacrylic, primary amine, secondary amine, tertiary amine, or quaternary amine having 1 to 10 carbon atoms, and R may be hydrogen, alkyl, aryl, alkylaryl, arylalkyl, alkenyl, cycloalkenyl, alkene, alkylene, arylene, alkylarylene, arylalkylene having 1 to 10 carbon atoms. It is one of cycloalkylene and in the above formula 1, R' is bonded to an organic material of the first adhesive layer and OR is chemically bonded to an inorganic material, and the display panel further comprises a display layer, a window located on the display layer and a hard coating layer located on the window, the hard coating layer and the first adhesive layer are in direct contact, the window comprises polyimide, the peel strength of the first adhesive layer against the window at room temperature (25°C) is 514 gf / in to 574 gf / in, and the peel strength of the first adhesive layer against the window at 60°C is 267 gf / in to 287 gf / in. Claim 2 delete Claim 3 A display device according to claim 1, wherein the thickness of the first adhesive layer is 25 μm to 100 μm. Claim 4 delete Claim 5 A display device according to claim 1, further comprising a second adhesive layer located between the display layer and the window, wherein the composition of the second adhesive layer and the first adhesive layer are different. Claim 6 In paragraph 5, the first adhesive layer is a display device located at the top of a plurality of adhesive layers included in the display device. Claim 7 In claim 1, the first adhesive layer is a pressure-sensitive adhesive (PSA) in the display device. Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 A display device according to claim 1, wherein the first adhesive layer has a storage modulus of 0.02 MPa to 0.035 MPa at 60°C. Claim 13 A display device according to claim 1, wherein the glass transition temperature of the first adhesive layer is -30 ℃ or lower. Claim 14 In claim 1, the first adhesive layer is a double-sided adhesive layer, and the display device. Claim 15 In paragraph 1, the display device is a foldable display device. Claim 16 In paragraph 15, the display device having a radius of curvature of 1.5R or more of the foldable display device. Claim 17 A display device according to claim 1, further comprising: a polarizing layer located between the display layer and the window; a third adhesive layer located between the display layer and the polarizing layer; a film layer located on the other side of the display layer; and a fourth adhesive layer located between the display layer and the film layer. Claim 18 In claim 17, a display device in which the composition of the third adhesive layer and the fourth adhesive layer is different from the composition of the first adhesive layer. Claim 19 A display device according to claim 1, further comprising a cushion layer located on the other side of the display panel; and a fifth adhesive layer for attaching the cushion layer and the display panel, wherein the composition of the fifth adhesive layer and the composition of the first adhesive layer are different. Claim 20 A display device comprising: a display panel; a protective layer positioned on the display panel; and a first adhesive layer positioned between the display panel and the protective layer, wherein the first adhesive layer comprises 0.05 w% to 1 w% of a compound represented by the following chemical formula 1, and the first adhesive layer has a creep of 20% or less at 60°C: [Chemical Formula 1] R'-Si-(OR)3, wherein R' may be one of alkyl, vinyl, carboxyl, glycidoxyl, epoxy, glycidyl, amino, mercapto, acrylic, methacrylic, primary amine, secondary amine, tertiary amine, quaternary amine having 1 to 10 carbon atoms, and R may be one of hydrogen, alkyl, aryl, alkylaryl, arylalkyl, alkenyl, cycloalkenyl, alken, alkylene, arylene, alkylarylene, arylalkylene, and cycloalkylene having 1 to 10 carbon atoms. In Chemical Formula 1, R' is bonded to an organic material of the first adhesive layer, OR is chemically bonded to an inorganic material, and the display panel further comprises a display layer, a window located on the display layer, and a hard coating layer located on the window, wherein the hard coating layer and the first adhesive layer are in direct contact, the window comprises polyimide, and the peel strength of the first adhesive layer against the window at room temperature (25°C) is 514 gf / in to 574 gf / in, and the peel strength of the first adhesive layer against the window at 60°C is 267 gf / in to 287 gf / in.

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