Display device and manufacturing method for the same

Abstract

A display device according to one embodiment of the present invention comprises a display panel including a display area and a non-display area surrounding the display area, a window disposed on the display panel, and an adhesive layer disposed on the display panel and comprising an ionic surfactant, wherein the adhesive layer comprises a first surface adjacent to the window and a second surface opposite to the first surface, and a first portion in which the concentration of the ionic surfactant increases from the first surface to the second surface.

Description

Technology Field

[0001] The present invention relates to a display device and a method for manufacturing the same, and more specifically, to a foldable display device and a method for manufacturing the same. Background Technology

[0002] Various types of display devices are used to provide image information, and such display devices can be divided into a display area corresponding to an active area and a non-display area in which a control unit, such as a circuit board for controlling the active areas, is placed.

[0003] Recently, structures for flexible display devices have been proposed that minimize non-display areas or bend non-display areas to improve visibility and reduce dead space. Meanwhile, in order to ensure that the display device has good durability even when dead space is reduced, there is a need to improve the reliability of the adhesive used to combine the components of the display device. The problem to be solved

[0004] The present invention aims to provide a display device with improved reliability and durability and a method for manufacturing the same by controlling the contact angle between a target substrate and an adhesive layer using an electric non-wetting phenomenon. means of solving the problem

[0005] A display device according to one embodiment of the present invention comprises a display panel including a display area and a non-display area surrounding the display area, a window disposed on the display panel, and an adhesive layer disposed on the display panel and comprising an ionic surfactant, wherein the adhesive layer comprises a first surface adjacent to the window and a second surface opposite to the first surface, and a first portion in which the concentration of the ionic surfactant increases from the first surface to the second surface.

[0006] The above first part can be superimposed on the above non-display area.

[0007] The adhesive layer further includes a second portion adjacent to the first portion, and in the second portion, the concentration of the ionic surfactant may be constant in the thickness direction of the adhesive layer.

[0008] The above second part can be superimposed on the above display area.

[0009] On a plane, the first part can surround the second part.

[0010] The first portion includes a first sub-adhesive portion adjacent to the first surface of the adhesive layer and a second sub-adhesive portion adjacent to the second surface of the adhesive layer, and the concentration of the ionic surfactant in the second sub-adhesive portion may be greater than the concentration of the ionic surfactant in the first sub-adhesive portion.

[0011] The first sub-adhesive may not include the ionic surfactant.

[0012] The adhesive layer can be placed between the display panel and the window.

[0013] The adhesive layer can be placed on the window.

[0014] The device further includes an upper protective film disposed between the display panel and the window, and the adhesive layer may be disposed between the display panel and the upper protective film, or between the window and the upper protective film.

[0015] The adhesive layer is disposed between the window and the upper protective film, and the display device is disposed between the display panel and the upper protective film and further comprises an additional adhesive layer comprising the ionic surfactant, wherein the additional adhesive layer comprises a third surface adjacent to the upper protective film and a fourth surface opposite to the third surface, and may include a third portion in which the concentration of the ionic surfactant increases from the third surface to the fourth surface.

[0016] The above ionic surfactant may include at least one of dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide, tetradecyltrimenylammonium bromide, and sodium dodecyl sulfate.

[0017] A display device according to one embodiment of the present invention comprises a display panel including a display area and a non-display area surrounding the display area, a window disposed on the display panel, and an adhesive layer disposed between the display panel and the window and comprising an ionic surfactant, wherein the concentration of the ionic surfactant increases from one side of the adhesive layer adjacent to the window to the other side of the adhesive layer adjacent to the display panel.

[0018] A method for manufacturing a display device according to one embodiment of the present invention comprises the steps of preparing a substrate, applying an adhesive composition containing an ionic surfactant onto the substrate to form a pre-adhesive layer, applying a voltage to the pre-adhesive layer, and curing the pre-adhesive layer.

[0019] The substrate includes a first region and a second region surrounding the first region, and in the step of applying voltage to the pre-adhesive layer, voltage may be applied to a portion of the pre-adhesive layer that overlaps with the first region.

[0020] In the step of applying voltage to the above-mentioned pre-adhesive layer, the ionic surfactant in the pre-adhesive layer superimposed on the first region can move to the upper part of the pre-adhesive layer.

[0021] Prior to the step of forming the above-mentioned pre-adhesive layer, the method may further include the step of placing an electrode on the lower part of the substrate to overlap with the first region.

[0022] The above adhesive composition can be applied by inkjet printing.

[0023] The step of applying voltage to the pre-adhesive layer and the step of curing the pre-adhesive layer can be performed simultaneously.

[0024] At 25℃, the viscosity of the above pre-adhesive layer may be 10 cP or more and 50 cP or less. Effects of the invention

[0025] The display device of one embodiment may exhibit improved reliability and durability characteristics by including parts with different concentration distributions of ionic surfactants.

[0026] A method for manufacturing a display device according to one embodiment includes the step of applying voltage to a pre-adhesive layer provided on a substrate, which can control the slope and contact angle of the edge portion of the adhesive layer, thereby providing a display device having improved reliability and durability characteristics. Brief explanation of the drawing

[0027] FIG. 1a is a perspective view showing the unfolded state of a display device according to one embodiment of the present invention. FIG. 1b is a perspective view showing the in-folding process of a display device according to one embodiment of the present invention. FIG. 1c is a perspective view showing the out-folding process of a display device according to one embodiment of the present invention. FIG. 2a is a perspective view showing the unfolded state of a display device according to one embodiment of the present invention. FIG. 2b is a perspective view showing the in-folding process of a display device according to one embodiment of the present invention illustrated in FIG. 2a. FIG. 3 is an exploded perspective view of a display device according to one embodiment of the present invention. FIG. 4 is a cross-sectional view of a display device according to one embodiment of the present invention. FIG. 5 is a cross-sectional view of a display panel according to one embodiment of the present invention. FIG. 6a is a cross-sectional view showing a part of the configuration of a display device according to one embodiment of the present invention. FIG. 6b is a cross-sectional view showing an adhesive layer according to one embodiment of the present invention. FIGS. 7a to 7c are cross-sectional views showing a part of the configuration of a display device according to one embodiment of the present invention. FIGS. 8A and FIGS. 8B are cross-sectional views illustrating problems that may occur in a display device. FIG. 9 is a flowchart illustrating a method for manufacturing a display device according to one embodiment of the present invention. FIGS. 10a to 10h are schematic drawings illustrating the steps of a method for manufacturing a display device according to an embodiment of the present invention. Specific details for implementing the invention

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0029] In this specification, where a component (or region, layer, part, etc.) is described as being "on," "connected," or "combined" with another component, it means that it may be directly connected / combined with the other component or that a third component may be placed between them.

[0030] Identical reference numerals denote identical components. Additionally, in the drawings, the thicknesses, proportions, and dimensions of the components are exaggerated for the effective illustration of the technical content. "And / or" includes all one or more combinations that the associated components may define.

[0031] Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0032] Additionally, terms such as "below," "lower side," "above," and "upper side" are used to describe the relationships between the components depicted in the drawings. These terms are relative concepts and are described based on the directions indicated in the drawings.

[0033] Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0034] In this specification, "directly placed" may mean that there are no additional layers, films, regions, plates, etc. between a part such as a layer, film, region, or plate and another part. For example, "directly placed" may mean placing two layers or two members without using additional members such as adhesive members between them.

[0035] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an overly ideal or overly formal sense unless explicitly defined herein.

[0036] Hereinafter, a display device according to one embodiment of the present invention and a display device of one embodiment including the same will be described with reference to the drawings.

[0037] FIG. 1a is a perspective view showing an unfolded state of a display device according to one embodiment. FIG. 1b is a perspective view showing an inner-folding process of the display device shown in FIG. 1a. FIG. 1c is a perspective view showing an outer-folding process of the display device shown in FIG. 1a.

[0038] The display device (ED) of one embodiment may be a device that is activated according to an electrical signal. For example, the display device (ED) may be a mobile phone, tablet, car navigation system, game console, or wearable device, but the embodiment is not limited thereto. In the specification of the present invention, such as FIG. 1a, the display device (ED) is exemplarily illustrated as a mobile phone.

[0039] In FIGS. 1a to 1c, the display device (ED) is illustrated as a foldable display device that is deformed into a folded shape, but the embodiment is not limited thereto, and the display device (ED) of one embodiment may be a flexible display device that can be bent or rolled to change its shape.

[0040] Meanwhile, FIG. 1a and the drawings below illustrate the first direction (DR1) to the fourth direction (DR4), and the directions indicated by the first to fourth directions (DR1, DR2, DR3, DR4) described in this specification are relative concepts and can be converted to other directions.

[0041] Referring to FIGS. 1a through 1c, a display device (ED) according to one embodiment may include a display surface (FS) defined by a first direction (DR1) and a second direction (DR2) intersecting the first direction (DR1). The display device (ED) may provide an image (IM) to a user through the display surface (FS). The display device (ED) of one embodiment may display an image (IM) toward a third direction (DR3) through a display surface (FS) parallel to each of the first direction (DR1) and the second direction (DR2). In this specification, the front (or top) and back (or bottom) surfaces of each component are defined based on the direction in which the image (IM) is displayed. In this specification, the direction in which the image (IM) is displayed may be defined as the third direction (DR3), and the fourth direction (DR4) may be defined as a direction opposite to the third direction (DR3).

[0042] A display device (ED) according to one embodiment can detect external input applied from the outside. The external input may include various forms of input provided from outside the display device (ED). For example, the external input may include contact by a part of the body, such as a user's hand, as well as external input applied when in close proximity to the display device (ED) or at a predetermined distance (e.g., hovering). In addition, it may have various forms such as force, pressure, temperature, light, etc.

[0043] The display surface (FS) of the display device (ED) may include an active area (F-AA) and a peripheral area (F-NAA). The active area (F-AA) may be an area that is activated according to an electrical signal. A display device (ED) according to one embodiment may display an image (IM) through the active area (F-AA). Additionally, various forms of external inputs may be detected in the active area (F-AA). The peripheral area (F-NAA) is adjacent to the active area (F-AA). The peripheral area (F-NAA) may have a predetermined color. The peripheral area (F-NAA) may surround the active area (F-AA). Accordingly, the shape of the active area (F-AA) may be substantially defined by the peripheral area (F-NAA). However, this is illustrated as an example, and the peripheral area (F-NAA) may be placed adjacent to only one side of the active area (F-AA) or may be omitted. A display device (ED) according to one embodiment of the present invention may include a display area of ​​various shapes and is not limited to any one embodiment.

[0044] Although not illustrated, the active area (F-AA) may include a sensing area. Various electronic modules may be placed in the sensing area. For example, the electronic module may include at least one of a camera module, a speaker, a light detection sensor, and a thermal detection sensor. The sensing area may detect an external subject received through the display surface (FS) or provide a sound signal, such as voice, to the outside through the display surface (FS). The electronic module may include multiple configurations and is not limited to any one embodiment.

[0045] In one embodiment, the back surface (RS) of the display device (ED) may be a surface facing the display surface (FS). In one embodiment, the back surface (RS) may be an outer surface of the display device (ED) and may not display images or video. However, the embodiment is not limited thereto, and the back surface (RS) may function as a second display surface where images or video are displayed. Additionally, the display device (ED) of one embodiment may further include a sensing area disposed on the back surface (RS). A camera, a speaker, a light detection sensor, etc., may also be disposed in the sensing area disposed on the back surface (RS).

[0046] A display device (ED) may include a folding area (FA1) and non-folding areas (NFA1, NFA2). A display device (ED) may include a plurality of non-folding areas (NFA1, NFA2). A display device (ED) of one embodiment may include a first non-folding area (NFA1) and a second non-folding area (NFA2) positioned with the folding area (FA1) in between. Meanwhile, while FIGS. 1a to 1c illustrate an embodiment of a display device (ED) including a single folding area (FA1), the embodiment is not limited thereto, and a plurality of folding areas may be defined in the display device (ED). However, the embodiment is not limited thereto, and a display device (ED) of one embodiment may be folded based on a plurality of folding axes so that a part of the display surface (FS) faces it, and the number of folding axes and the number of non-folding areas accordingly are not particularly limited.

[0047] Referring to FIGS. 1b and 1c, a display device (ED) according to one embodiment may be folded with respect to a first folding axis (FX1). The first folding axis (FX1) shown in FIGS. 1b and 1c is a virtual axis extending in a first direction (DR1), and the first folding axis (FX1) may be parallel to the long side direction of the display device (ED). However, the embodiment is not limited thereto, and the extension direction of the first folding axis (FX1) is not limited to the first direction (DR1).

[0048] The first folding axis (FX1) may extend along the first direction (DR1) on the display surface (FS) or extend along the first direction (DR1) from the bottom of the back surface (RS). Referring to FIG. 1b, in one embodiment, the first non-folding area (NFA1) and the second non-folding area (NFA2) face each other, and the display device (ED) may be in-folded so that the display surface (FS) is not exposed to the outside. Additionally, referring to FIG. 1c, the display device (ED) according to one embodiment may be folded along the first folding axis (FX1) and transformed into an out-folding state in which one area overlapping with the first non-folding area (NFA1) and another area overlapping with the second non-folding area (NFA2) of the back surface (RS) face each other.

[0049] FIG. 2a is a perspective view showing an unfolded state of a display device according to one embodiment. FIG. 2b is a perspective view showing the in-folding process of the display device shown in FIG. 2a.

[0050] In one embodiment, the display device (ED-a) may be folded based on a second folding axis (FX2) that extends in one direction parallel to the first direction (DR1). FIG. 2b illustrates a case where the extension direction of the second folding axis (FX2) is parallel to the extension direction of the short side of the display device (ED-a). However, the embodiment is not limited thereto.

[0051] A display device (ED-a) according to one embodiment may include at least one folding region (FA2) and non-folding regions (NFA3, NFA4) adjacent to the folding region (FA2). The non-folding regions (NFA3, NFA4) may be spaced apart from each other with the folding region (FA2) in between.

[0052] The folding region (FA2) has a predetermined curvature and radius of curvature. In one embodiment, the first non-folding region (NFA3) and the second non-folding region (NFA4) face each other, and the display device (ED-a) can be inner-folded so that the display surface (FS) is not exposed to the outside.

[0053] Additionally, unlike what is illustrated, in one embodiment, the display device (ED-a) may be out-folded so that the display surface (FS) is exposed to the outside. Meanwhile, in one embodiment, the first display surface (FS) of the display device (ED-a) may be visible to the user in an unfolded state, and the second display surface (RS) may be visible to the user in an in-folded state. The second display surface (RS) may include an electronic module area in which an electronic module comprising various configurations is placed.

[0054] A display device (ED-a) according to one embodiment may include a second display surface (RS), and the second display surface (RS) may be defined as a surface facing at least a portion of the first display surface (FS). The second display surface (RS) may be visible to the user in an in-folded state. The second display surface (RS) may include an electronic module area in which an electronic module including various configurations is disposed. Meanwhile, in one embodiment, an image may be provided through the second display surface (RS).

[0055] In one embodiment, the display device (ED, ED-a) may be configured such that an in-folding or out-folding operation is alternately repeated from an unfolding operation, but the embodiment is not limited thereto. In one embodiment, the display device (ED, ED-a) may be configured to select any one of an unfolding operation, an in-folding operation, and an out-folding operation.

[0056] In FIGS. 1a to 2b, the display device (ED, ED-a) is depicted as a foldable display device that is deformed into a folded shape, but the embodiment is not limited thereto, and the display device (ED) of one embodiment may be a flexible display device that can be bent or rolled to change its shape.

[0057] FIG. 3 is an exploded perspective view of a display device according to one embodiment, and FIG. 4 is a cross-sectional view of a display device according to one embodiment. FIG. 5 is a cross-sectional view of a display panel according to one embodiment. FIG. 3 is an exemplary exploded perspective view of a display device according to one embodiment shown in FIG. 1a. FIG. 4 is a cross-sectional view showing a portion corresponding to line I-I' of FIG. 3.

[0058] Referring to FIGS. 3 and 4, a display device (ED) of one embodiment may include a display panel (DP) and upper functional layers (UFL) disposed above the display panel (DP). Additionally, a display device (ED) of one embodiment may include lower functional layers (LFL) disposed below the display panel (DP). Although FIGS. 3 and 4 describe a display device (ED) illustrated in FIGS. 1a to 1c as an embodiment, the following description may be equally applicable to a display device (ED-a) illustrated in FIGS. 2a and 2b.

[0059] The window (WD) may cover the entire outer surface of the display module (DM). The window (WD) may have a shape corresponding to the shape of the display panel (DP). Additionally, the display device (ED) of one embodiment may include a housing (HAU) that accommodates the display panel (DP) and the support module (SM), etc. The housing (HAU) may be coupled with the window (WD). Although not illustrated, the housing (HAU) may further include a hinge structure to facilitate folding or bending.

[0060] In a display device (ED) of one embodiment, a display panel (DP) can display an image according to an electrical signal and transmit / receive information regarding an external input. The display panel (DP) can be defined as a display area (DP-DA) and a non-display area (DP-NDA). The display area (DP-DA) can be defined as an area that emits an image provided by the display panel (DP).

[0061] The non-display area (DP-NDA) is adjacent to the display area (DP-DA). For example, the non-display area (DP-NDA) may surround the display area (DP-DA). However, this is illustrated as an example, and the non-display area (DP-NDA) may be defined in various shapes and is not limited to any one embodiment. According to one embodiment, the display area (DP-DA) of the display panel (DP) may correspond to at least a part of the active area (F-AA, FIG. 1a).

[0062] In a display device (ED) according to one embodiment, the display panel (DP) may include a folding display portion (FA-D) and a non-folding display portion (NFA1-D, NFA2-D). The folding display portion (FA-D) is a portion corresponding to a folding area (FA1, FIG. 1a), and the non-folding display portion (NFA1-D, NFA2-D) may be a portion corresponding to a non-folding area (NFA1, NFA2, FIG. 1a).

[0063] Referring to FIG. 5, the display panel (DP) may be configured to generate an image and detect an input applied from the outside. For example, the display panel (DP) may include a display layer (110) and a sensor layer (120). The thickness of the display panel (DP) may be 25 micrometers (μm) to 35 micrometers, for example, 30 micrometers, and the thickness of the display panel (100) is not limited thereto.

[0064] The display layer (110) may be a configuration that substantially generates an image. The display layer (110) may be a light-emitting display layer, for example, the display layer (110) may be an organic light-emitting display layer, a quantum dot display layer, or a micro LED display layer.

[0065] The display layer (110) may include a base layer (111), a circuit layer (112), a light-emitting element layer (113), and an encapsulation layer (114).

[0066] The base layer (111) may include a synthetic resin film. The synthetic resin layer may include a thermosetting resin. The base layer (111) may have a multilayer structure. For example, the base layer (111) may have a three-layer structure consisting of a synthetic resin layer, an adhesive layer, and a synthetic resin layer. In particular, the synthetic resin layer may be a polyimide-based resin layer, and the material is not particularly limited. The synthetic resin layer may include at least one of an acrylic resin, a methacrylate resin, a polyisoprene resin, a vinyl resin, an epoxy resin, a urethane resin, a cellulose resin, a siloxane resin, a polyamide resin, and a perylene resin. In addition, the base layer (111) may include a glass substrate or an organic / inorganic composite material substrate, etc.

[0067] A circuit layer (112) may be placed on a base layer (111). The circuit layer (112) may include an insulating layer, a semiconductor pattern, a conductive pattern, and a signal line, etc. An insulating layer, a semiconductor layer, and a conductive layer are formed on the base layer (111) by means such as coating or deposition, and subsequently, the insulating layer, the semiconductor layer, and the conductive layer may be selectively patterned through a plurality of photolithography processes. Subsequently, a semiconductor pattern, a conductive pattern, and a signal line included in the circuit layer (112) may be formed.

[0068] The light-emitting element layer (113) may be disposed on the circuit layer (112). The light-emitting element layer (113) may include a light-emitting element. For example, the light-emitting element layer (113) may include an organic light-emitting material, a quantum dot, a quantum rod, or a micro LED.

[0069] The encapsulation layer (114) may be disposed on the light-emitting element layer (113). The encapsulation layer (114) may include sequentially stacked inorganic layers, organic layers, and inorganic layers, but the layers constituting the encapsulation layer (114) are not limited thereto.

[0070] Inorganic layers can protect the light-emitting element layer (113) from moisture and oxygen, and organic layers can protect the light-emitting element layer (113) from foreign substances such as dust particles. Inorganic layers may include a silicon nitride layer, a silicon oxynitride layer, a silicon oxide layer, a titanium oxide layer, or an aluminum oxide layer. Organic layers may include an acrylic-based organic layer, but are not limited thereto.

[0071] The sensor layer (120) may be placed on the display layer (110). The sensor layer (120) may detect external input applied from the outside. The external input may be user input. User input may include various forms of external input such as a part of the user's body, light, heat, a pen, or pressure.

[0072] The sensor layer (120) can be formed on the display layer (110) through a continuous process. In this case, the sensor layer (120) can be described as being placed directly on the display layer (110). Being placed directly means that no third component is placed between the sensor layer (120) and the display layer (110). That is, no separate adhesive member may be placed between the sensor layer (120) and the display layer (110).

[0073] Alternatively, the sensor layer (120) may be bonded to the display layer (110) through an adhesive member. The adhesive member may include a conventional adhesive or a pressure-sensitive adhesive.

[0074] Referring again to FIG. 4, a window (WD) is placed on a display panel (DP). The window (WD) may include an optically transparent insulating material. The window (WD) may protect the display panel (DP). That is, the window (WD) may be a cover window that covers the top of the display panel (DP).

[0075] An image (IM, FIG. 1a) generated from a display panel (DP) can be provided to a user by passing through a window (WD). The window (WD) may provide a touch surface of a display device (ED). In a display device (ED) including a folding area (FA1), the window (WD) may be a flexible window that can be folded.

[0076] An adhesive layer (AD) may be disposed on a display panel (DP). The adhesive layer (AD) may combine at least two of the components included in the display panel (DP) and the upper functional layers. For example, the adhesive layer (AD) may combine a window (WD) with an upper protective film (IAL) or combine a window (WD) with a protective layer (PF). An adhesive layer (AD) according to one embodiment may include an ionic surfactant (ISF, FIG. 6b). In this specification, the ionic surfactant (ISF, FIG. 6b) may include a cationic surfactant or an anionic surfactant. The adhesive layer (AD) will be described in detail later. Meanwhile, although FIG. 3 and FIG. 4 show the adhesive layer (AD) disposed between the window (WD) and the upper protective film (IAL), this is exemplary and the embodiments are not limited thereto.

[0077] In a display device (ED) of one embodiment, the upper functional layers (UFL) may comprise a plurality of adhesive layers. The upper functional layers (UFL) of the display device (ED) of one embodiment may comprise additional adhesive layers other than the adhesive layer (AD) of one embodiment. For example, the display device (ED) of one embodiment may comprise a first upper adhesive layer (AP-P) and a second upper adhesive layer (AP-I). The first upper adhesive layer (AP-P) may be disposed between a protective layer (PF) and a window (WD). The window (WD) and the protective layer (PF) may be attached by the first upper adhesive layer (AP-P). The second upper adhesive layer (AP-I) may be disposed between an upper protective film (IAL) and a display panel (DP). The upper protective film (IAL) and the display panel (DP) may be attached by the second upper adhesive layer (AP-I).

[0078] The first upper adhesive layer (AP-P) and the second upper adhesive layer (AP-I) may include a conventional adhesive or a pressure-sensitive adhesive. The first upper adhesive layer (AP-P) and the second upper adhesive layer (AP-I) may be an optically clear adhesive film (OCA) or an optically clear adhesive resin layer (OCR).

[0079] A protective layer (PF) may be placed on top of the window (WD). The protective layer (PF) may be a functional layer that protects the upper surface of the window (WD).

[0080] A protective layer (PF) according to one embodiment is polyethyleneterephthalate (PET), poly(butylene terephthalate) (PBT), polyethylene naphthalene (PEN), polycarbonate (PC), poly(methylmethacrylate) (PMMA), polystyrene (PS), polyvinyl chloride (PVC), polyethersulfone (PES), polypropylene (PP), polyamide (PA), modified polyphenylene ether (m-PPO), polyoxymethylene (POM), polysulfone (PSU), polyphenylene sulfide (PPS), polyimide (PI), polyethyleneimine, It may comprise at least one polymer resin selected from PEI), polyether ether ketone (PEEK), polyamide imide (PAI), polyarylate (PAR), and thermoplastic polyurethane (TPU). The protective layer (PF) may be a polymer film layer, and for example, in one embodiment, the protective layer (PF) may be a polyethylene terephthalate (PET) film or a thermoplastic polyurethane (TPU) film.

[0081] The protective layer (PF) may further include materials such as anti-fingerprint coating agents, antistatic agents, and hard coating agents to serve as a functional layer. Meanwhile, the protective layer (PF) may have a multilayer laminated structure and may further include an anti-fingerprint coating layer, an antistatic coating layer, a hard coating layer, etc., as separate functional layers.

[0082] Lower functional layers (LFL) may be disposed below the display panel (DP). For example, the lower functional layers (LFL) may include a lower film (LF) and a support module (SM). The support module (SM) may include a support plate (MP) and a lower support member (BSM). The components included in the lower functional layers (LFL) are not limited to the components described above. At least some of the components described above may be omitted, and other components may be added.

[0083] A display device (ED) of one embodiment may include a lower film (LF) disposed below a display panel (DP). The lower film (LF) may be disposed below the display panel (DP) to protect the lower part of the display panel (DP). A display device (ED) of one embodiment may include a lower adhesive layer (AP-L) that bonds the display panel (DP) and the lower film (LF).

[0084] The lower film (LF) may be a polymer film. For example, the lower film (LF) may include a polyethylene terephthalate (PET) film or a polyimide (PI) film. The lower film (LF) can prevent scratches from occurring on the back surface of the display panel (DP) during the display panel (DP) manufacturing process. Additionally, the lower film (LF) can prevent deformation of the display panel (DP) by protecting the display panel (DP) against external pressure. The lower film (LF) may have a structure in which a single film layer or multiple film layers are laminated.

[0085] The lower adhesive layer (AP-L) may be placed between the display panel (DP) and the lower film (LF). The lower adhesive layer (AP-L) may be an optically clear adhesive film (OCA) or an optically clear adhesive resin layer (OCR). However, the embodiments are not limited thereto, and the lower adhesive layer (AP-L) may include an acrylic adhesive or a silicone adhesive, etc. Additionally, in one embodiment, the lower adhesive layer (AP-L) may be omitted.

[0086] A display device (ED) according to one embodiment may include a support module (SM) disposed below a display panel (DP). The support module (SM) may include a support plate (MP) and a lower support member (BSM).

[0087] A support plate (MP) may be positioned below a display panel (DP). In one embodiment, the support plate (MP) may comprise a metal material or a polymer material. For example, the support plate (MP) may be formed from stainless steel, aluminum, or an alloy thereof. Alternatively, the support plate (MP) may be formed from carbon fiber reinforced plastic (CFRP), etc. However, the embodiments are not limited thereto, and the support plate (MP) may comprise a non-metallic material, plastic, glass fiber reinforced plastic, or glass.

[0088] A plurality of openings (OP) may be defined in the support plate (MP). The support plate (MP) may include an opening pattern (OP-PT) comprising a plurality of openings (OP). The opening pattern (OP-PT) may correspond to a folding region (FA1).

[0089] The lower support member (BSM) may include a support member (SPM) and a filling part (SAP). The support member (SPM) may be a portion that overlaps with most of the area of ​​the display panel (DP). The filling part (SAP) may be a portion disposed on the outer side of the support member (SPM) and overlapping with the outer edge of the display panel (DP).

[0090] The lower support member (BSM) may include at least one of a support layer (SP), a cushion layer (CP), a shielding layer (EMP), and an interlayer bonding layer (ILP). Meanwhile, the configuration of the lower support member (BSM) is not limited to that shown in FIG. 4, etc., and the configuration of the lower support member (BSM) may vary depending on the size, shape, or operating characteristics of the display device (ED). For example, some of the support layer (SP), cushion layer (CP), shielding layer (EMP), and interlayer bonding layer (ILP) may be omitted, their stacking order may be modified to a different order from FIG. 4, or additional configurations other than those shown may be included. For example, the lower support member (BSM) may further include a digitizer, etc.

[0091] The support layer (SP) may include a metal material or a polymer material. The support layer (SP) may be disposed on the lower side of the support plate (MP). For example, the support layer (SP) may be a thin film metal substrate.

[0092] The support layer (SP) may include a first sub-support layer (SSP1) and a second sub-support layer (SSP2) that are spaced apart from each other in a second direction (DR2). The first sub-support layer (SSP1) and the second sub-support layer (SSP2) may be spaced apart from each other based on a portion corresponding to the folding axis (FX1). The support layer (SP) can improve the folding or bending characteristics of the display device (ED) by being provided as the first sub-support layer (SSP1) and the second sub-support layer (SSP2) that are spaced apart from each other in the folding area (FA1).

[0093] The cushion layer (CP) may be disposed below the support layer (SP). The cushion layer (CP) can prevent compression and plastic deformation of the support plate (MP) caused by external impact and force. The cushion layer (CP) can improve the impact resistance of the display device (ED). The cushion layer (CP) may include a sponge, foam, or an elastomer such as urethane resin. Additionally, the cushion layer (CP) may be formed by including at least one of an acrylic polymer, a urethane polymer, a silicone polymer, and an imide polymer. However, the embodiments are not limited thereto.

[0094] Additionally, the cushion layer (CP) may include a first sub-cushion layer (CP1) and a second sub-cushion layer (CP2) spaced apart from each other in a second direction (DR2). The first sub-cushion layer (CP1) and the second sub-cushion layer (CP2) may be spaced apart from each other in a portion corresponding to the folding axis (FX1). By providing the cushion layer (CP) as the first sub-cushion layer (CP1) and the second sub-cushion layer (CP2) spaced apart from each other in the folding area (FA1), the folding or bending characteristics of the display device (ED) can be improved.

[0095] The shielding layer (EMP) may be an electromagnetic shielding layer or a heat dissipation layer. Additionally, the shielding layer (EMP) may function as a bonding layer. The interlayer bonding layer (ILP) may bond the support plate (MP) and the lower support member (BSM). The interlayer bonding layer (ILP) may be provided in the form of a bonding resin layer or an adhesive tape. Although FIG. 3 shows the interlayer bonding layer (ILP) divided into two parts spaced apart from each other in the portion corresponding to the folding area (FA1), the embodiment is not limited thereto, and the interlayer bonding layer (ILP) may be provided as a single layer that is not spaced apart from each other in the folding area (FA1).

[0096] The filling portion (SAP) may be positioned on the outer edge of the support layer (SP) and the cushion layer (CP). The filling portion (SAP) may be positioned between the support plate (MP) and the housing (HAU). The filling portion (SAP) may fill the space between the support plate (MP) and the housing (HAU) and secure the support plate (MP).

[0097] Additionally, the display device (ED) of one embodiment may further include a module adhesive layer (AP-DM) disposed between the display module (DM) and the support module (SM). The module adhesive layer (AP-DM) may be an optically clear adhesive film (OCA) or an optically clear adhesive resin layer (OCR). Meanwhile, although not illustrated, additional adhesive layers may be disposed between each member included in the support module (SM).

[0098] FIG. 6a is a cross-sectional view showing a part of the configuration of a display device according to one embodiment. FIG. 6b is a cross-sectional view of an adhesive layer according to one embodiment. However, the lower functional layers (LFL) of the display device (ED) shown in FIG. 3 and FIG. 4 are omitted from FIG. 6a for convenience of explanation.

[0099] Referring to FIG. 6a, the window (WD) may include an upper surface (WD-UF) and a lower surface (WD-LF) facing the upper surface (WD-UF). The upper surface (WD-UF) of the window (WD) may be adjacent to a protective layer (PF), and the lower surface (WD-LF) of the window (WD) may be adjacent to a display panel (DP). The lower surface (WD-LF) of the window (WD) may be facing the upper surface (WD-UF) of the window (WD) in a third direction (DR3).

[0100] The adhesive layer (AD) may include a first surface (AD-F1) and a second surface (AD-F2) facing the first surface (AD-F1) in a third direction (DR3). In one embodiment, the first surface (AD-F1) of the adhesive layer (AD) may be positioned adjacent to the window (WD). The first surface (AD-F1) of the adhesive layer (AD) may be in contact with the lower surface (WD-LF) of the window (WD).

[0101] Referring to FIGS. 6a and 6b, the adhesive layer (AD) of one embodiment may comprise an ionic surfactant (ISF). The ionic surfactant (ISF) may comprise a cationic surfactant or an anionic surfactant. In FIG. 6b, the ionic surfactant (ISF) is depicted as a particle with a circular cross-section, but this is illustrated illustratively for convenience of explanation and does not represent the actual form of the ionic surfactant (ISF).

[0102] In one embodiment, the concentration distribution of the ionic surfactant (ISF) within a portion of the adhesive layer (AD) may vary. In a portion of the adhesive layer (AD), the concentration of the ionic surfactant (ISF) may increase as it moves from the first surface (AD-F1) to the second surface (AD-F2). That is, in the adhesive layer (AD), the concentration of the ionic surfactant (ISF) may increase as it moves away from the window (WD) from the first surface (AD-F1).

[0103] The adhesive layer (AD) of one embodiment may include a first portion (AD1) and a second portion (AD2). In the adhesive layer (AD), the first portion (AD1) and the second portion (AD2) may be distinguished according to the concentration distribution of an ionic surfactant (ISF).

[0104] The first portion (AD1) of the adhesive layer (AD) may be a portion where the concentration of the ionic surfactant (ISF) increases as it moves from the first surface (AD-F1) toward the second surface (AD-F2). That is, the first portion (AD1) of the adhesive layer (AD) may have a concentration distribution in which the ionic surfactant (ISF) increases as it moves from the first surface (AD-F1) of the adhesive layer (AD) toward the second surface (AD-F2) of the adhesive layer (AD). In one embodiment, the ionic surfactant (ISF) in the first portion (AD1) may have a concentration distribution that increases as it moves away from the window (WD).

[0105] The second portion (AD2) of the adhesive layer (AD) may be a portion where the concentration of the ionic surfactant (ISF) is constant in the third direction (DR3), which is the thickness direction of the adhesive layer (AD). That is, in the second portion (AD2), the ionic surfactant (ISF) may have a uniform concentration distribution as it moves from the first surface (AD-F1) of the adhesive layer (AD) to the second surface (AD-F2) of the adhesive layer (AD).

[0106] Referring to FIG. 6a, the first part (AD1) of the adhesive layer (AD) may overlap the non-display area (DP-NDA), and the second part (AD2) of the adhesive layer (AD) may overlap the display area (DP-DA). That is, the first part (AD1) of the adhesive layer (AD) may be formed by overlapping the non-display area (DP-NDA), and the second part (AD2) of the adhesive layer (AD) may be formed by overlapping the display area (DP-DA). Meanwhile, although FIG. 6a depicts the adhesive layer (AD) overlapping the entire non-display area (DP-NDA), it is not limited thereto. For example, unlike what is shown in FIG. 6a, the adhesive layer (AD) may overlap only a part of the non-display area (DP-NDA).

[0107] In one embodiment, the first portion (AD1) of the adhesive layer (AD) may be formed by overlapping with the non-display area (DP-NDA). The first portion (AD1) of the adhesive layer (AD) may be the portion to which voltage is applied during the step of applying voltage to the pre-adhesive layer (P-AD, FIG. 10d) in the method for manufacturing a display device of one embodiment described later. In one embodiment, the second portion (AD2) of the adhesive layer (AD) may be formed by overlapping with the display area (DP-DA). The second portion (AD2) of the adhesive layer (AD) may be the portion to which voltage is not applied during the step of applying voltage to the pre-adhesive layer (P-AD, FIG. 10d) in the method for manufacturing a display device of one embodiment described later.

[0108] In one embodiment, a first portion (AD1) of the adhesive layer (AD) may include a first sub-adhesive portion (AD1-1) and a second sub-adhesive portion (AD1-2). The first sub-adhesive portion (AD1-1) may be formed adjacent to a first surface (AD-F1) of the adhesive layer (AD), and the second sub-adhesive portion (AD1-2) may be formed adjacent to a second surface (AD-F2) of the adhesive layer (AD). The second sub-adhesive portion (AD1-2) may be formed with a predetermined thickness in a third direction (DR3), which is the thickness direction, from the second surface (AD-F2) of the adhesive layer (AD).

[0109] In one embodiment, the concentration value of the ionic surfactant (ISF) in the adhesive layer (AD) may decrease as it moves from the second sub-adhesive portion (AD1-2) of the first part (AD1) to the first sub-adhesive portion (AD1-1). The concentration of the ionic surfactant (ISF) in the second sub-adhesive portion (AD1-2) may be greater than the concentration of the ionic surfactant (ISF) in the first sub-adhesive portion (AD1-1). That is, the number of ionic surfactants (ISF) contained in the second sub-adhesive portion (AD1-2) of the first part (AD1) may be greater than the number of ionic surfactants (ISF) contained in the first sub-adhesive portion (AD1-1) of the first part (AD1). The concentration of the ionic surfactant (ISF) contained in the second sub-adhesion portion (AD1-2) of the first portion (AD1) may be greater than 50% and less than or equal to 95% of the total concentration of the ionic surfactant (ISF) contained in the first portion (AD1).

[0110] In one embodiment, the first sub-adhesive portion (AD1-1) may be a portion that does not contain an ionic surfactant (ISF). In this case, the second sub-adhesive portion (AD1-2) may represent a portion from the second surface (AD-F2) of the adhesive layer (AD) to the first surface (AD-F1) where the concentration of the ionic surfactant (ISF, FIG. 6) becomes zero. However, it is not limited thereto.

[0111] The ionic surfactant (ISF) contained in the second sub-adhesive portion (AD1-2) may have a first concentration. The ionic surfactant (ISF) contained in the first sub-adhesive portion (AD1-1) may have a second concentration. The ionic surfactant (ISF) contained in the second portion (AD2) may have a third concentration. The first concentration of the ionic surfactant (ISF) in the second sub-adhesive portion (AD1-2) may be greater than the second concentration of the ionic surfactant (ISF) in the first sub-adhesive portion (AD1-1) and greater than the third concentration of the ionic surfactant (ISF) in the second portion (AD2) of the adhesive layer (AD). In one embodiment, the concentrations of the ionic surfactant (ISF) in the second portion (AD2), the first sub-adhesive portion (AD1-1), and the second sub-adhesive portion (AD1-2) may satisfy the following Equation 1.

[0112] [Equation 1]

[0113] D AD1-2 > D AD2 ≥ D AD1-1

[0114] In the above Equation 1, D AD1-2 represents the first concentration of the ionic surfactant (ISF) in the second sub-adhesion portion (AD1-2), and D AD1-1 represents the second concentration of the ionic surfactant (ISF) in the first sub-adhesive (AD1-1), and D AD2 represents the third concentration of the ionic surfactant (ISF) in the second part (AD2). Referring to Equation 1 above, the first concentration may be greater than the second concentration and the third concentration. The third concentration may be equal to or greater than the second concentration.

[0115] In one embodiment, the thickness (d) of the adhesive layer (AD) AD ) may be 35㎛ or more and 75㎛ or less. For example, the thickness (d) of the adhesive layer (AD) AD ) may be 40㎛ or more and 70㎛ or less. The thickness (d) of the adhesive layer (AD) ADIf ) is less than 35㎛, it may not exhibit sufficient adhesive strength, and the thickness (d) of the adhesive layer (AD) AD If ) exceeds 75㎛, the thick thickness may degrade the folding or bending characteristics of the flexible display device. The thickness (d) of the adhesive layer (AD) AD If the above range is satisfied, it exhibits sufficient adhesive strength while having excellent durability against bending deformation, making it suitable for foldable display devices or bending display devices.

[0116] In one embodiment, the ionic surfactant (ISF) may include at least one of dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and sodium dodecyl sulfate.

[0117] In one embodiment, the weight ratio of the ionic surfactant (ISF) based on the total weight of the adhesive layer (AD) in the adhesive layer (AD) may be 1 wt% or more and 10 wt% or less. If the weight ratio of the ionic surfactant (ISF) is less than 1 wt%, dewetting characteristics may not be sufficiently expressed when voltage is applied to the adhesive layer (AD), and if the weight ratio of the ionic surfactant (ISF) is greater than 10 wt%, aggregation of the ionic surfactant (ISF) may occur within the adhesive layer (AD).

[0118] The adhesive layer (AD) has a flat upper surface in the second portion (AD2), and in the first portion (AD1), the thickness may gradually decrease in the third direction (DR3) toward the edge of the adhesive layer (AD). That is, the first portion (AD1) of the adhesive layer (AD) may include an inclined side. In this specification, the portion where the thickness of the adhesive layer (AD) gradually decreases may be referred to as a slope. The slope of the adhesive layer (AD) has a first length (d s It can have ). The first length (d) of the slope of the adhesive layer (AD). sIf the slope becomes too long, the slope may be visible from outside the display device (ED), which can degrade the image quality. According to the present invention, an ionic surfactant (ISF) is introduced into an adhesive composition for forming an adhesive layer (AD), and by applying voltage to a specific part of the adhesive composition to control the surface tension of the adhesive composition, the contact angle of the adhesive layer (AD) can be changed, and as a result, the slope length of the adhesive layer (AD) can be reduced.

[0119] FIGS. 7a to 7c are cross-sectional views of a display device (ED) according to an embodiment of the present invention. FIGS. 7a to 7c illustrate a cross-sectional view of the display device (ED) taken along I-I' of FIG. 3. Hereinafter, in describing a display device (ED) according to an embodiment of the present invention with reference to FIGS. 7a to 7c, the same reference numerals are assigned to the components previously described in FIGS. 3, FIG. 4, FIG. 6a, and FIG. 6b, and a detailed description is omitted.

[0120] Referring to FIGS. 7a and 7b, the arrangement of the adhesive layer (AD) in a display device according to one embodiment may differ from that of the display device shown in FIG. 6a.

[0121] Referring to FIG. 7a, an adhesive layer (AD) may be placed on a window (WD). Specifically, the adhesive layer (AD) may be placed between the window (WD) and a protective layer (PF). A third upper adhesive layer (AP-W) may be placed between the window (WD) and an upper protective film (IAL). The third upper adhesive layer (AP-W) may include a conventional adhesive or a pressure-sensitive adhesive. The third upper adhesive layer (AP-W) may be an optically clear adhesive film (OCA) or an optically clear adhesive resin layer (OCR). Meanwhile, regarding the description of the adhesive layer (AD) shown in FIG. 7a, the content described above in FIG. 6a and FIG. 6b may be applied in the same way.

[0122] The adhesive layer (AD) may include a first surface (AD-F1) and a second surface (AD-F2) facing the first surface (AD-F1) in a third direction (DR3). In one embodiment, the first surface (AD-F1) of the adhesive layer (AD) may be positioned adjacent to the window (WD). As illustrated in FIG. 7a, when the adhesive layer (AD) is positioned on the window (WD), the first surface (AD-F1) of the adhesive layer (AD) may be in contact with the upper surface (WD-UF) of the window (WD).

[0123] The concentration distribution of the ionic surfactant (ISF) within the adhesive layer (AD) may vary. The concentration of the ionic surfactant (ISF) may increase as one moves from the first surface (AD-F1) of the adhesive layer (AD) to the second surface (AD-F2) of the adhesive layer (AD). That is, the concentration of the ionic surfactant (ISF) may increase as one moves away from the window (WD) in the direction from the first surface (AD-F1) of the adhesive layer (AD).

[0124] Additionally, the adhesive layer (AD) of one embodiment may include a first portion (AD1) and a second portion (AD2). The first portion (AD1) of the adhesive layer (AD) may be a portion where the concentration of the ionic surfactant (ISF) increases as one moves from the first surface (AD-F1) toward the second surface (AD-F2). That is, the ionic surfactant (ISF) in the first portion (AD1) may have a concentration distribution that increases as one moves away from the window (WD). The second portion (AD2) of the adhesive layer (AD) may be a portion where the concentration of the ionic surfactant (ISF) is constant in the third direction (DR3), which is the thickness direction of the adhesive layer (AD). That is, in the second portion (AD2), the ionic surfactant (ISF) may have a uniform concentration distribution as one moves from the first surface (AD-F1) of the adhesive layer (AD) toward the second surface (AD-F2) of the adhesive layer (AD).

[0125] Meanwhile, at least one of the second upper adhesive layer (AP-I) and the third upper adhesive layer (AP-W) in the display device (ED) shown in FIG. 7a may be omitted.

[0126] Referring to FIG. 7b, an adhesive layer (AD) may be placed between an upper protective film (IAL) and a display panel (DP). A first upper adhesive layer (AP-P) may be placed between the protective layer (PF) and the window (WD), and a third upper adhesive layer (AP-W) may be placed between the window (WD) and the upper protective film (IAL). However, this is not limited thereto, and at least one of the first upper adhesive layer (AP-P) and the third upper adhesive layer (AP-W) may be omitted. Meanwhile, regarding the description of the adhesive layer (AD) shown in FIG. 7b, the content described above in FIG. 6a and FIG. 6b may be applied in the same way.

[0127] The adhesive layer (AD) may include a first surface (AD-F1) and a second surface (AD-F2) facing the first surface (AD-F1) in a third direction (DR3). In one embodiment, the first surface (AD-F1) of the adhesive layer (AD) may be positioned adjacent to the window (WD).

[0128] The upper protective film (IAL) may include an upper surface and a lower surface facing the upper surface. The upper surface of the upper protective film (IAL) may be adjacent to the window (WD), and the lower surface of the upper protective film (IAL) may be adjacent to the display panel (DP). The lower surface of the upper protective film (IAL) may be facing the upper surface of the upper protective film (IAL) in a third direction (DR3). As shown in FIG. 7b, when an adhesive layer (AD) is placed between the upper protective film (IAL) and the display panel (DP), the first surface (AD-F1) of the adhesive layer (AD) may be in contact with the lower surface of the upper protective film (IAL).

[0129] Referring to FIG. 7c, a display device (ED) according to one embodiment may further include an additional adhesive layer (AD-A) compared to the display device (ED) illustrated in FIG. 6a. That is, the display device (ED) of one embodiment may include an adhesive layer (AD) disposed between a window (WD) and an upper protective film (IAL), and may further include an additional adhesive layer (AD-A) disposed between the upper protective film (IAL) and a display panel (DP). Meanwhile, regarding the description of the adhesive layer (AD) illustrated in FIG. 7c, the content described above in FIG. 6a and FIG. 6b may be applied in the same way.

[0130] A display device (ED) of one embodiment may further include an additional adhesive layer (AD-A) disposed between a display panel (DP) and an upper protective film (IAL). The additional adhesive layer (AD-A) may include a third surface (AD-A-F1) and a fourth surface (AD-A-F2) facing the third surface (AD-A-F1) in a third direction (DR3). In one embodiment, the third surface (AD-A-F1) of the additional adhesive layer (AD-A) may be adjacent to a window (WD), and the fourth surface (AD-A-F2) may be adjacent to a display panel (DP). The third surface (AD-A-F1) of the additional adhesive layer (AD-A) may be in contact with the lower surface of the upper protective film (IAL).

[0131] The description of the additional adhesive layer (AD-A) shown in FIG. 7c can be applied in the same way as the description in FIG. 6a and 6b. That is, the additional adhesive layer (AD-A) differs only in its arrangement structure from the adhesive layer (AD), and its composition may be the same as the adhesive layer (AD) described in FIG. 6a and 6b.

[0132] The additional adhesive layer (AD-A) may contain an ionic surfactant (ISF, FIG. 6b). The concentration distribution of the ionic surfactant (ISF, FIG. 6b) within the additional adhesive layer (AD-A) may vary. The concentration of the ionic surfactant (ISF, FIG. 6b) may increase from the third surface (AD-A-F1) to the fourth surface (AD-A-F2) in the additional adhesive layer (AD-A).

[0133] An additional adhesive layer (AD-A) of one embodiment may include a third portion (AD3) and a fourth portion (AD4). In the additional adhesive layer (AD-A), the third portion (AD3) and the fourth portion (AD4) may be distinguished according to the concentration distribution of an ionic surfactant (ISF, FIG. 6b).

[0134] The third portion (AD3) of the additional adhesive layer (AD-A) may be a portion where the concentration of the ionic surfactant (ISF, FIG. 6b) increases as it moves from the third surface (AD-A-F1) toward the fourth surface (AD-A-F2). That is, the third portion (AD3) of the additional adhesive layer (AD-A) may have a concentration distribution in which the ionic surfactant (ISF, FIG. 6b) increases as it moves from the third surface (AD-A-F1) of the additional adhesive layer (AD-A) toward the fourth surface (AD-A-F2) of the additional adhesive layer (AD-A). In one embodiment, the ionic surfactant (ISF, FIG. 6b) in the third portion (AD3) may have a concentration distribution that increases as it moves away from the window (WD).

[0135] The fourth portion (AD4) of the additional adhesive layer (AD-A) may be a portion where the concentration of the ionic surfactant (ISF, FIG. 6b) is constant in the third direction (DR3), which is the thickness direction of the additional adhesive layer (AD-A). That is, in the fourth portion (AD4), the ionic surfactant (ISF, FIG. 6b) may have a uniform concentration distribution as it moves from the third surface (AD-A-F1) of the additional adhesive layer (AD-A) to the fourth surface (AD-A-F2) of the additional adhesive layer (AD-A).

[0136] The third part (AD3) of the additional adhesive layer (AD-A) may overlap the non-display area (DP-NDA), and the fourth part (AD4) of the additional adhesive layer (AD-A) may overlap the display area (DP-DA). That is, the third part (AD3) of the additional adhesive layer (AD-A) may be formed by overlapping the non-display area (DP-NDA), and the fourth part (AD4) of the additional adhesive layer (AD-A) may be formed by overlapping the display area (DP-DA). Meanwhile, although FIG. 7c depicts the additional adhesive layer (AD-A) overlapping the entire non-display area (DP-NDA), it is not limited thereto. For example, unlike what is depicted in FIG. 7c, the additional adhesive layer (AD-A) may overlap only a part of the non-display area (DP-NDA).

[0137] In one embodiment, the third portion (AD3) of the additional adhesive layer (AD-A) may include a third sub-adhesive portion (AD3-1) and a fourth sub-adhesive portion (AD3-2). The third sub-adhesive portion (AD3-1) may be formed adjacent to the third surface (AD-A-F1) of the additional adhesive layer (AD-A), and the fourth sub-adhesive portion (AD3-2) may be formed adjacent to the fourth surface (AD-A-F2) of the additional adhesive layer (AD-A). The fourth sub-adhesive portion (AD3-2) may be formed with a predetermined thickness in the third direction (DR3), which is the thickness direction, from the fourth surface (AD-A-F2) of the additional adhesive layer (AD-A). The concentration of the ionic surfactant (ISF, FIG. 6b) in the fourth sub-adhesive (AD3-2) may be greater than the concentration of the ionic surfactant (ISF, FIG. 6b) in the third sub-adhesive (AD3-1).

[0138] In one embodiment, the thickness (d) of the additional adhesive layer (AD-A) AD-A ) may be 35㎛ or more and 75㎛ or less. For example, the thickness (d) of the additional adhesive layer (AD-A) AD-A ) may be 40㎛ or more and 70㎛ or less. The thickness (d) of the additional adhesive layer (AD-A) AD-A If ) is less than 35㎛, it may not exhibit sufficient adhesive strength, and the thickness (d) of the additional adhesive layer (AD-A) AD-A If ) exceeds 75㎛, the folding or bending characteristics of the flexible display device may be degraded due to the thick thickness. The thickness (d) of the additional adhesive layer (AD-A) AD-A If the above range is satisfied, it exhibits sufficient adhesive strength while having excellent durability against bending deformation, making it suitable for foldable display devices or bending display devices.

[0139] FIGS. 8a and 8b are cross-sectional views illustrating potential problems that may occur in a display device. Meanwhile, configurations identical to those described in FIGS. 3 to 7c are given the same reference numerals and their descriptions are omitted.

[0140] Adhesives are used to attach each layer included in an ED (Electrical Display Device). If a pressure-sensitive adhesive (PSA) is used for this purpose, it is cumbersome to manufacture and the production cost is high, and processability issues such as steaming may occur during the die-cutting process. To solve these problems, methods such as inkjet printing are used to form the adhesive layer applied to the ED. In the case of methods such as inkjet printing, the use of an adhesive composition with low viscosity may be required to increase jettaability during ejection. When the viscosity of the adhesive composition is low, the adhesive composition applied to the substrate moves easily, which may increase the contact area between the substrate and the adhesive composition; however, the contact angle between the substrate and the adhesive composition decreases, which may result in the formation of a slope where the thickness gradually decreases at the edge.

[0141] For example, as illustrated in FIG. 8a, when a low-viscosity adhesive composition is provided on a window (WD) to form an adhesive layer (AD'), the adhesive composition has a strong tendency to increase the contact area with the surface of the window (WD), which can increase the contact area between the window (WD) and the adhesive composition. In this state, when the adhesive composition is cured to form the adhesive layer (AD'), the contact angle (θ1) between the window (WD) and the adhesive layer (AD') is reduced, and a slope is formed in which the thickness gradually decreases at the edge of the adhesive layer (AD'). If the length (d1) of this slope increases, as illustrated in FIG. 8b, a large deformation may occur in the slope portion after the folding evaluation of the display device, and a deformed adhesive layer (AD'') may be formed. Consequently, the curved slope of the deformed adhesive layer (AD'') is visible from outside the display device, which may degrade the image quality.

[0142] Therefore, when forming an adhesive layer by applying a low-viscosity adhesive composition, it may be effective to increase the surface tension of the adhesive composition at the edge portion to improve uniformity while reducing the slope length at the edge portion of the adhesive layer. However, there are limitations to the characteristics of materials that can be applied to combine adhesive compositions, and it is difficult to control the characteristics of surface tension while meeting various characteristics of the adhesive composition, such as viscosity, sprayability, and curing characteristics required during the process. According to the present invention, by introducing an ionic surfactant into an adhesive composition for forming an adhesive layer and selectively applying voltage to a specific portion of the adhesive composition applied on a substrate, it is possible to improve the overall thickness uniformity of the adhesive layer while reducing the slope length at the edge portion.

[0143] Hereinafter, a method for manufacturing a display device of one embodiment is described with reference to FIG. 9 and FIG. 10a to 10h. In describing the method for manufacturing a display device of one embodiment, the description of the display device of one embodiment described above may be applied to the display device. In the following description of the method for manufacturing a display device of one embodiment, content that overlaps with the description of the display device of one embodiment described above will not be explained again, and the differences will be explained primarily.

[0144] A method for manufacturing a display device of one embodiment may represent a method for manufacturing a display device (ED) of one embodiment described in FIGS. 1 to 7c. One embodiment provides a method for manufacturing a display device comprising an adhesive layer (AD) disposed on a display panel (DP) of the display device (ED).

[0145] FIG. 9 is a flowchart illustrating a method for manufacturing a display device of one embodiment.

[0146] Referring to FIG. 9, a method for manufacturing a display device of one embodiment may include the steps of preparing a substrate (S100), applying an adhesive composition containing an ionic surfactant onto the substrate to form a pre-adhesive layer (S200), applying a voltage to the pre-adhesive layer (S300), and curing the pre-adhesive layer (S400).

[0147] FIGS. 10a to 10h are schematic diagrams illustrating the steps of preparing an adhesive layer (AD) according to one embodiment. FIG. 10a shows the step of preparing a substrate (RP), FIGS. 10b to 10d show the step of forming a preliminary adhesive layer (P-AD) by providing an adhesive composition (AD-RC) on the substrate (RP), FIGS. 10e and 10f show the step of applying voltage to the preliminary adhesive layer (P-AD), and FIGS. 10g and 10h show the step of curing the preliminary adhesive layer (P-AD) to form an adhesive layer (AD).

[0148] A method for manufacturing a display device according to one embodiment may include the step (S100) of preparing a substrate. Referring to FIG. 10a, a method for manufacturing a display device according to one embodiment may include the step of providing a substrate (RP) on which an adhesive layer (AD, FIG. 10g) is formed. The substrate (RP) may provide a reference surface on which the adhesive layer (AD, FIG. 10g) is formed. For example, the substrate (RP) may be a window (WD) as described in FIG. 6a.

[0149] Referring to FIG. 10a, the substrate (RP) may include a first region (AA1) and a second region (AA2). The first region (AA1) may refer to an area that overlaps with the pre-adhesive layer (P-AD, FIG. 10e) to which voltage is applied during the step (S300) of applying voltage to the pre-adhesive layer in the method for manufacturing a display device of an embodiment described later. That is, the first region (AA1) may refer to an area that overlaps with the electrode (ET, FIG. 10e) placed on the underside of the substrate (RP) in the method for manufacturing a display device of an embodiment described later.

[0150] The first region (AA1) may be adjacent to the second region (AA2). For example, the first region (AA1) may surround the second region (AA2). However, it is not limited thereto, and the first region (AA1) may be defined in various shapes. According to one embodiment, the first region (AA1) of the substrate (RP) may correspond to at least a portion of the non-display area (DP-NDA) of the display panel (DP, FIG. 4).

[0151] Referring to FIGS. 10b to 10d, a pre-adhesive layer (P-AD) can be formed by applying an adhesive composition (AD-RC) onto a substrate (RP). The adhesive composition (AD-RC) is provided in a liquid form, and the pre-adhesive layer (P-AD) may be a liquid coating layer before curing.

[0152] The adhesive composition (AD-RC) may comprise a base resin (BR) and an ionic surfactant (ISF). The adhesive composition (AD-RC) may be applied to a first region (AA1) and a second region (AA2) of a substrate (RP). Before applying voltage to the pre-adhesive layer (P-AD), the ionic surfactant (ISF) contained in the pre-adhesive layer (P-AD) may be uniformly dispersed and disposed in the base resin (BR). The base resin (BR) may comprise an acrylic resin, a urethane resin, a fluoropolymer resin, an epoxy resin, a polyester resin, a polyamide resin, a silicone resin, or a combination thereof. The adhesive composition (AD-RC) may comprise an uncured oligomer or monomer. The uncured oligomer or monomer may comprise a crosslinking reactor. Additionally, the adhesive composition (AD-RC) may comprise an initiator. The type of initiator is not particularly limited as long as it can promote the curing reaction, and, for example, it may be a thermal initiator or a photoinitiator.

[0153] In one embodiment, the adhesive composition (AD-RC) may comprise at least one photoinitiator. In one embodiment, the photoinitiator may be a photoinitiator that is activated by light in the ultraviolet region. The photoinitiator may be a photoinitiator that is activated by ultraviolet light having a center wavelength in the wavelength region of 100 nm to 400 nm. If the adhesive composition (AD-RC) comprises a plurality of photoinitiators, the different photoinitiators may be activated by ultraviolet light in different center wavelength regions. Meanwhile, in this specification, the center wavelength refers to the wavelength that represents the maximum intensity of the emission peak in the emission spectrum of the light source.

[0154] The photoinitiator is 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, and It may be any one selected from 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan-1-one(2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methylpropan-1-one).

[0155] In addition, the photoinitiator is 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl phosphinate, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, [1-(4-phenylsulfanylbenzoyl)heptylideneamino]benzoate, [1-[9-ethyl-6-(2-methylbenzoyl)carbazol-3-yl]ethylideneamino] acetate, and bis(2,4-cyclopentadienyl)bis[2,6-difluoro-3-(1-pyryl)phenyl] It may be any one selected from titanium(IV) (Bis(2,4-cyclopentadienyl)bis[2,6-difluoro-3-(1-pyrryl)phenyl] titanium(IV)). However, it is not limited thereto.

[0156] The adhesive composition (AD-RC) may further include additives as needed. To control the physical properties required for the adhesive composition, general additives known in the art may be appropriately selected. Examples include, but are not limited to, light stabilizers, crosslinking agents, antioxidants, chain transfer agents, photosensitizers, polymerization inhibitors, leveling agents, surfactants, adhesion improvers, plasticizers, UV absorbers, storage stabilizers, antistatic agents, inorganic fillers, pigments, and dyes. Additives may be used alone or in combination of two or more types.

[0157] In one embodiment, an inkjet printing method may be used to apply the adhesive composition (AD-RC). The adhesive composition (AD-RC) may be provided through a nozzle (NZ) and may be provided so as to maintain a constant coating thickness on a substrate (RP).

[0158] In inkjet printing methods, materials with relatively low viscosity may be required for excellent jettability. In one embodiment, the viscosity of the adhesive composition (AD-RC) may be 10 cP or more and 50 cP or less at room temperature (25°C). If the viscosity of the adhesive composition (AD-RC) is less than 10 cP, a problem may occur where the adhesive composition (AD-RC) flows out from the side edges of the substrate (RP) when the adhesive composition (AD-RC) is applied onto the substrate (RP). Additionally, if the viscosity of the adhesive composition (AD-RC) exceeds 50 cP, application by the inkjet method may become difficult due to the high viscosity, and the adhesive composition (AD-RC) may not spread on the substrate (RP), making it difficult to form an adhesive layer (AD) with a uniform composition.

[0159] As illustrated in FIG. 10d, the pre-adhesive layer (P-AD) has a flat upper surface in the second region (AA2), and in the first region (AA1), the thickness may gradually decrease in the third direction (DR3) toward the edge portion of the pre-adhesive layer (P-AD). The portion where the thickness of the pre-adhesive layer (P-AD) gradually decreases before voltage is applied may be referred to as the first slope. The first slope of the pre-adhesive layer (P-AD) has a second length (d P-AD It may have ). In one embodiment, the second length (d P-AD ) can be 80 µm or more and 250 µm or less.

[0160] Before voltage is applied, the pre-adhesive layer (P-AD) has a first contact angle (θ P-AD It can have a first contact angle (θ) between the upper surface (RP-UF) of the substrate (RP) and the pre-adhesive layer (P-AD) before voltage is applied. P-AD ) may be between 30° and 60°. For example, the first contact angle (θ P-AD ) can be between 45° and 50°.

[0161] Referring to FIGS. 10e and 10f, after a pre-adhesive layer (P-AD) is formed on a substrate (RP), an electrode (ET) for applying voltage to the pre-adhesive layer (P-AD) may be provided. An electrode (ET) for applying voltage to the pre-adhesive layer (P-AD) may be disposed on the underside of the substrate (RP). In one embodiment, the electrode (ET) may be disposed on the underside of the substrate (RP) so as to overlap with a first region (AA1) of the substrate (RP). The electrode (ET) may not overlap with a second region (AA2) of the substrate (RP). Meanwhile, FIGS. 10a to 10f illustrate that the electrode (ET) is disposed on the underside of the substrate (RP) after the pre-adhesive layer (P-AD) is formed, but is not limited thereto. For example, the electrode (ET) may be disposed on the underside of the substrate (RP) before the adhesive composition (AD-RC) for forming the pre-adhesive layer (P-AD) is applied on the substrate (RP).

[0162] An electrode (ET) may be disposed on the back surface of the substrate (RP). The electrode (ET) may be made of a conductive material. The electrode (ET) forms electrically different polarities. A (+) electrode is formed on one side of the electrode (ET), and a (-) electrode is formed on the other side of the electrode (ET). The (+) electrode may be connected to either the electrode (ET) or the pre-adhesive layer (P-AD), and the (-) electrode may be connected to the other.

[0163] In order to control the length of the slope at the edge while ensuring the uniformity of the adhesive layer (AD), the contact angle between the pre-adhesive layer (P-AD) and the substrate (RP) at the edge must be adjusted to be greater than a specific value. In the present invention, the shape of the edge portion of the pre-adhesive layer (P-AD) overlapping the first region (AA1) can be changed by utilizing the electro-dewetting phenomenon. As the shape of the edge portion of the pre-adhesive layer (P-AD) overlapping the first region (AA1) changes, the contact angle between the substrate (RP) and the pre-adhesive layer (P-AD) can change. The electro-dewetting phenomenon occurs in the pre-adhesive layer (P-AD) overlapping the first region (AA1), and accordingly, the contact angle between the substrate (RP) and the pre-adhesive layer (P-AD) can change.

[0164] Referring to FIG. 10f, the ionic surfactant (ISF) may be a material comprising a hydrophobic group (HP) and a hydrophilic group (PG). The ionic surfactant (ISF) may serve to increase the surface tension acting on the upper surface of the pre-adhesive layer (P-AD). By applying a voltage with the same polarity as the hydrophilic group (PG) of the ionic surfactant (ISF) to the electrode (ET), contact angle control between the pre-adhesive layer (P-AD) and the substrate (RP) can be achieved more efficiently. In FIG. 10d and FIG. 10f, the ionic surfactant (ISF) is depicted as a cationic surfactant having a cation as the hydrophilic group (PG), but is not limited thereto. The ionic surfactant (ISF) may be an anionic surfactant having an anion as the hydrophilic group (PG).

[0165] The hydrophilic group (PG) of the ionic surfactant (ISF) may have a polarity opposite to the charge applied to the pre-adhesive layer (P-AD). The hydrophilic group (PG) of the ionic surfactant (ISF) may have the same polarity as the charge applied to the electrode (ET) and a polarity opposite to the charge applied to the pre-adhesive layer (P-AD). For example, as shown in FIG. 10f, if the ionic surfactant (ISF) contains a hydrophilic group (PG) with a (+) charge, a (-) charge may be applied to the pre-adhesive layer (P-AD) and a (+) charge may be applied to the electrode (ET). Accordingly, different charges accumulate at the interface between the electrode (ET) and the substrate (RP) and at the interface between the substrate (RP) and the pre-adhesive layer (P-AD), and the contact angle of the pre-adhesive layer (P-AD) changes due to the electrostatic force between the charges accumulated at the interface between the substrate (RP) and the pre-adhesive layer (P-AD) and the hydrophilic group (PG) of the ionic surfactant (ISF).

[0166] Referring to FIG. 10f, the ionic surfactant (ISF) can move to the upper surface of the pre-adhesive layer (P-AD) due to the repulsion between the charges accumulated at the interface between the pre-adhesive layer (P-AD) and the substrate (RP) in the first region (AA1) and the hydrophilic group (PG) of the ionic surfactant (ISF). As a result, the wettability of the pre-adhesive layer (P-AD) in the first region (AA1) changes. Specifically, the surface tension between the pre-adhesive layer (P-AD) and the external gas in the first region (AA1) increases, which can increase the contact angle between the pre-adhesive layer (P-AD) and the substrate (RP). When a voltage is applied, the pre-adhesive layer (P-AD) [at] a second contact angle (θ AD It can have a second contact angle (θ) between the upper surface (RP-UF) of the substrate (RP) and the pre-adhesive layer (P-AD) when voltage is applied to the pre-adhesive layer (P-AD). AD ) can be 65° or greater. For example, the second contact angle (θ AD ) may be 65° or greater and 90° or less. In one embodiment, the second contact angle (θ) of the pre-adhesive layer (P-AD) after voltage is applied AD ) is the first contact angle (θ) of the pre-adhesive layer (P-AD) before voltage is applied P-AD It can be larger than )

[0167] When voltage is applied, the length of the slope may decrease as the contact angle between the pre-adhesive layer (P-AD) and the substrate (RP) increases. As illustrated in FIG. 10f, when voltage is applied, the pre-adhesive layer (P-AD) has a flat upper surface in the second region (AA2), and in the first region (AA1), the thickness may gradually decrease in the third direction (DR3) toward the edge portion of the pre-adhesive layer (P-AD). The portion where the thickness of the pre-adhesive layer (P-AD) gradually decreases when voltage is applied may be referred to as the second slope. The second slope of the pre-adhesive layer (P-AD) has a first length (d s It may have ). In one embodiment, the first length (d s) may be less than 80㎛. For example, the first length (d s ) may be 0.1 μm or more and less than 80 μm. In one embodiment, the first length (d) of the pre-adhesive layer (P-AD) after voltage is applied is s ) is the second length (d) of the pre-adhesive layer (P-AD) before voltage is applied. P-AD It can be smaller than )

[0168] In the step of applying voltage to the pre-adhesive layer (P-AD), the concentration distribution of the ionic surfactant (ISF) present in the pre-adhesive layer (P-AD) can be controlled by adjusting the area and / or the magnitude of the voltage in the first region (AA1) placed on the electrode (ET). As shown in FIG. 10f, by placing the electrode (ET) so as to overlap only the first region (AA1) of the substrate (RP), the ionic surfactant (ISF) contained in the pre-adhesive layer (P-AD) overlapping the first region (AA1) can move to one side of the pre-adhesive layer (P-AD) depending on the application of voltage. Specifically, depending on the applied voltage, the ionic surfactant (ISF) contained in the pre-adhesive layer (P-AD) overlapping the first region (AA1) can move to the upper side of the pre-adhesive layer (P-AD). At this time, the degree of movement of the ionic surfactant (ISF) can be controlled according to the area of ​​the first region (AA1) overlapping with the electrode (ET) and / or the magnitude of the applied voltage. Accordingly, the concentration of the ionic surfactant (ISF) in the first sub-adhesive (AD1-1) and the second sub-adhesive (AD1-2) formed thereafter can be controlled. That is, the first concentration of the ionic surfactant (ISF) in the second sub-adhesive (AD1-2) and the second concentration of the ionic surfactant (ISF) in the first sub-adhesive (AD1-1) can be determined by the area overlapping between the electrode (ET) and the substrate (RP), the magnitude of the applied voltage, etc.

[0169] An electrode (ET) may not be placed below the second region (AA2) of the substrate (RP). Since the electrode (ET) is not placed below the second region (AA2) of the substrate (RP), the ionic surfactant (ISF) contained in the pre-adhesive layer (P-AD) overlapping the second region (AA2) can be uniformly dispersed. The surface tension on the upper surface of the pre-adhesive layer (P-AD) overlapping the second region (AA2) may be smaller than the surface tension on the upper surface of the pre-adhesive layer (P-AD) overlapping the first region (AA1). Accordingly, the uniformity of the thickness of the pre-adhesive layer (P-AD) overlapping the second region (AA2) can be improved.

[0170] Referring to FIGS. 10e to 10g, a method for manufacturing a display device (ED) according to one embodiment includes the step of curing a pre-adhesive layer (P-AD) to form an adhesive layer (AD). Light may be irradiated onto the front surface of the pre-adhesive layer (P-AD), and the pre-adhesive layer (P-AD), which includes a photoinitiator, may be cured by the light. For example, the pre-adhesive layer (P-AD) may be cured by ultraviolet light. However, it is not limited thereto, and if the pre-adhesive layer (P-AD) includes a heat initiator, heat may be applied to the front surface of the pre-adhesive layer (P-AD), and the pre-adhesive layer (P-AD) may be cured by the heat.

[0171] In one embodiment, the step of applying voltage to the pre-adhesive layer (S300) and the step of curing the pre-adhesive layer (S400) can be performed simultaneously. As shown in FIG. 10e, voltage is applied to the pre-adhesive layer (P-AD) overlapping the first region (AA1) to move the ionic surfactant (ISF) to the top of the pre-adhesive layer (P-AD), and the pre-adhesive layer (P-AD) is cured simultaneously to fix the arrangement state of the ionic surfactant (ISF). Accordingly, the pre-adhesive layer (P-AD) can be separated into a pre-second layer containing most of the ionic surfactant (ISF) in the first region (AA1) and a pre-first layer containing a lower concentration of ionic surfactant (ISF) than the pre-second layer, or not containing ionic surfactant (ISF). The preliminary second layer and the preliminary first layer can be cured to form a second sub-adhesive (AD1-2) and a first sub-adhesive (AD1-1) as illustrated in FIG. 10g and FIG. 10h. Although not illustrated, the adhesive layer (AD) produced in the steps of FIG. 10a to 10h can be applied to the display device (ED) described above. For example, one side of the adhesive layer (AD) produced in the steps of FIG. 10a to 10h can be attached to the display panel (DP) or upper protective film (IAL) described above, and the substrate (RP) can be a window (WD) or an upper protective film (IAL).

[0172] In inkjet printing methods, a relatively low-viscosity adhesive composition may be required for excellent jettability. However, while applying a low-viscosity material to a substrate can increase the contact area between the substrate and the adhesive composition, the contact angle between the substrate and the adhesive composition tends to decrease. Consequently, a slope may be formed at the edge of the adhesive layer formed after curing, in which the thickness of the adhesive layer gradually decreases. If the length of this slope increases, the slope becomes visible from outside the display device, which may degrade image quality.

[0173] In the present invention, by controlling the viscosity of the adhesive composition for forming the adhesive layer to a value or lower and simultaneously performing a process of applying voltage to the adhesive composition applied on the substrate during the curing process, the contact angle between the substrate and the adhesive layer can be maintained above a certain range. In addition, by introducing an ionic surfactant into the adhesive composition for forming the adhesive layer, the contact area at the interface between the substrate and the adhesive layer can be increased, and the contact angle between the substrate and the adhesive layer at the side edge can be significantly increased, thereby reducing the length of the slope formed at the edge of the adhesive layer, which can improve the durability and reliability of the display device (ED).

[0174] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or those with ordinary knowledge in the relevant technical field will understand that various modifications and changes can be made to the invention without departing from the spirit and technical scope of the invention as set forth in the claims below. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims. Explanation of the symbols

[0175] ED: Display device DP: Display panel DP-DA: Display area DP-NDA: Non-display area WD: Window IAL: Top protective film AD: Adhesive layer AD-F1: First surface AD-F2: 2nd side AD1: 1st part AD2: Part 2 AD1-1: Part 1 sub-adhesive AD1-2: Second subadhesion area ISF: Ionic surfactant RP: Substrate AA1: Second region AA2: Second region AD-RC: Adhesive composition P-AD: Pre-adhesive layer P-AD: Pre-adhesive layer ET: Electrode

Claims

Claim 1 A display device comprising: a display panel including a display area and a non-display area surrounding the display area; a window disposed on the display panel; and an adhesive layer disposed on the display panel and comprising an ionic surfactant, wherein the adhesive layer comprises a first surface adjacent to the window and a second surface opposite to the first surface, and a first portion in which the concentration of the ionic surfactant increases from the first surface to the second surface. Claim 2 In claim 1, the first part is a display device that overlaps the non-display area. Claim 3 A display device according to claim 1, wherein the adhesive layer further comprises a second portion adjacent to the first portion, and in the second portion, the concentration of the ionic surfactant is constant in the thickness direction of the adhesive layer. Claim 4 In paragraph 3, the second part is a display device that overlaps the display area. Claim 5 In paragraph 3, the first part on the plane is a display device that surrounds the second part. Claim 6 A display device according to claim 1, wherein the first portion comprises a first sub-adhesive portion adjacent to the first surface of the adhesive layer; and a second sub-adhesive portion adjacent to the second surface of the adhesive layer, wherein the concentration of the ionic surfactant in the second sub-adhesive portion is greater than the concentration of the ionic surfactant in the first sub-adhesive portion. Claim 7 In claim 6, the first sub-adhesive portion is a display device that does not include the ionic surfactant. Claim 8 In claim 1, the adhesive layer is a display device disposed between the display panel and the window. Claim 9 In claim 1, the adhesive layer is a display device disposed on the window. Claim 10 A display device according to claim 1, further comprising an upper protective film disposed between the display panel and the window, wherein the adhesive layer is disposed between the display panel and the upper protective film, or between the window and the upper protective film. Claim 11 In claim 10, the adhesive layer is disposed between the window and the upper protective film, and the display device is disposed between the display panel and the upper protective film and further comprises an additional adhesive layer comprising the ionic surfactant, wherein the additional adhesive layer comprises a third surface adjacent to the upper protective film and a fourth surface opposite to the third surface, and a third portion in which the concentration of the ionic surfactant increases from the third surface to the fourth surface. Claim 12 A display device according to claim 1, wherein the ionic surfactant comprises at least one of dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and sodium dodecyl sulfate. Claim 13 A display device comprising: a display panel including a display area and a non-display area surrounding the display area; a window disposed on the display panel; and an adhesive layer disposed between the display panel and the window and comprising an ionic surfactant, wherein the concentration of the ionic surfactant increases from one side of the adhesive layer adjacent to the window to the other side of the adhesive layer adjacent to the display panel. Claim 14 A method for manufacturing a display device comprising: a step of preparing a substrate; a step of forming a pre-adhesive layer by applying an adhesive composition containing an ionic surfactant onto the substrate; a step of applying a voltage to the pre-adhesive layer; and a step of curing the pre-adhesive layer. Claim 15 A method for manufacturing a display device according to claim 14, wherein the substrate comprises a first region and a second region surrounded by the first region, and in the step of applying voltage to the pre-adhesive layer, applying voltage to a portion of the pre-adhesive layer that overlaps with the first region. Claim 16 A method for manufacturing a display device according to claim 15, wherein, in the step of applying voltage to the pre-adhesive layer, the ionic surfactant in the pre-adhesive layer superimposed on the first region moves to the upper part of the pre-adhesive layer. Claim 17 A method for manufacturing a display device according to claim 15, further comprising the step of placing an electrode on the lower part of the substrate to overlap the first region prior to the step of forming the pre-adhesive layer. Claim 18 In claim 14, the adhesive composition is a method for manufacturing a display device applied by an inkjet printing method. Claim 19 A method for manufacturing a display device according to claim 14, wherein the step of applying voltage to the pre-adhesive layer and the step of curing the pre-adhesive layer are performed simultaneously. Claim 20 A method for manufacturing a display device according to claim 14, wherein the viscosity of the pre-adhesive layer at 25°C is 10 cP or more and 50 cP or less.

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