Double-sided tape

Abstract

A double-sided tape comprising: a first adhesive layer comprising about 100 parts by weight of an acrylic polymer, about 1 to about 2 parts by weight of a silane coupling agent, and about 0.1 to about 0.18 parts by weight of carbon black; a foamed polymer layer disposed on the first adhesive layer comprising a polyurethane foam; a sandwich polymer layer disposed on the foamed polymer layer comprising a polyolefin (PO), a polyethylene terephthalate (PET), a polyester, or a combination thereof; and a second adhesive layer disposed on the sandwich polymer layer comprising about 100 parts by weight of an acrylic polymer, about 1 to about 2 parts by weight of a silane coupling agent, and about 0.1 to about 0.18 parts by weight of carbon black, wherein the total thickness of the double-sided tape is about 0.4 to about 1.3 millimeters.

Description

[0001] This application is a divisional application of patent application No. 201811598799.3, filed on December 26, 2018, entitled "Double-sided Adhesive Tape". This application claims priority and benefit to Korean patent application No. 10-2017-0180387, filed with the Korean Intellectual Property Office on December 27, 2017, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure relates to double-sided tape and display devices including said double-sided tape. Background Technology

[0003] In the field of display devices such as monitors, televisions (“TV”) and mobile devices, double-sided tape can be used to adhere display panels and mold frames that support the display panels.

[0004] Double-sided tape used in curved display devices with curved surfaces can improve the visibility of the curved display device.

[0005] Since the display panel and the mold frame can be connected and fixed to each other as needed while maintaining a predetermined curvature, the curved display device may have large shear and tensile stresses transmitted to the double-sided tape, and silicone resin can be additionally applied to the gap space between the display panel and the mold frame to withstand the stress, for example, when the double-sided tape is not torn.

[0006] However, the exterior of the silicone resin may deteriorate due to overflow when too much silicone resin is applied, and the fixing force of the display panel may be weakened when too little silicone resin is applied. Summary of the Invention

[0007] The implementation provides a double-sided tape that can effectively fix the display panel to the mold frame in the display device even when silicone resin is omitted, thanks to the improved properties of the double-sided tape, such as adhesion, bonding and durability.

[0008] The implementation scheme provides a display device in which the display panel is stably fixed to the mold frame.

[0009] The implementation scheme is not limited to the purposes mentioned above, and other purposes not mentioned can be clearly understood by those skilled in the art from the following description.

[0010] A double-sided adhesive tape is disposed between a curved display panel having curvature in at least one direction and a curved mold frame having a shape corresponding to the display panel, and is configured to secure the display panel and the mold frame to each other. The double-sided adhesive tape comprises: a first adhesive layer comprising about 100 parts by weight of an acrylic polymer, about 1 to about 2 parts by weight of a silane coupling agent, and about 0.1 to about 0.18 parts by weight of carbon black, the first adhesive layer having a crosslinking degree of about 40% to about 49% by weight and an optical density (OD) of about 5 or greater; a foamed polymer layer disposed on the first adhesive layer, the foamed polymer layer comprising polyurethane foam, the foamed polymer layer having an OD of about 5 or greater and a thickness of about 0.3 mm to about 1.15 mm; and a sandwich polymer layer disposed on the foamed polymer layer, the sandwich polymer layer comprising polyolefin (PO), polyethylene terephthalate (PET), polyester, or combinations thereof, the sandwich polymer layer having an OD of about 5 or greater and a thickness of about 0.045 mm. The double-sided tape has a thickness of about 0.055 mm; and a second adhesive layer disposed on the interlayer polymer layer, the second adhesive layer comprising about 100 parts by weight of acrylic polymer, about 1 part by weight to about 2 parts by weight of silane coupling agent and about 0.1 part by weight to about 0.18 parts by weight of carbon black, the second adhesive layer having a crosslinking degree of about 40% by weight to about 49% by weight and an OD of about 5 or greater than 5, wherein the total thickness of the double-sided tape is about 0.4 mm to about 1.3 mm.

[0011] In an exemplary embodiment, the silane coupling agent may comprise a compound represented by Formula 1: Formula 1

[0012] In Equation 1, OR represents an amino group, an epoxy alkyl group, a mercapto group, or an allyl group, and each OR independently represents an alkoxy group or an acetoxy group.

[0013] In an exemplary embodiment, the first adhesive layer, the second adhesive layer, or a combination thereof may further comprise an isocyanate curing agent.

[0014] In an exemplary embodiment, the isocyanate curing agent may include toluene-2,4-diisocyanate or a derivative thereof.

[0015] In an exemplary embodiment, based on 100 parts by weight of the acrylic polymer, the first adhesive layer, the second adhesive layer, or a combination thereof may contain about 6 parts by weight to about 7 parts by weight of the isocyanate curing agent.

[0016] In an exemplary embodiment, the foamed polymer layer may have a content of approximately 0.36 g / cm³. 3 (approximately 0.6 g / cm) 3 The density.

[0017] In an exemplary embodiment, the curvature can be from about 600 R to about 4,000 R.

[0018] In an exemplary embodiment, when measured 24 hours after the double-sided tape was attached to the mold frame and the display panel, the double-sided tape may have a strength of 15.47 kgf / inch. 2 ) or greater than 15.47 kgf / inch 2 The vertical ultimate tensile strength.

[0019] In an exemplary embodiment, when measured 30 minutes after the double-sided tape was attached to the mold frame and the display panel, the double-sided tape may have a strength of 12.8 kgf / inch. 2 or greater than 12.8 kgf / inch 2 The horizontal ultimate tensile strength. Attached Figure Description

[0020] The above and other aspects and features of this disclosure will become more apparent from the exemplary embodiments described in detail with reference to the accompanying drawings, in which: Figure 1 This is a plan view illustrating an embodiment of the display device; Figure 2 It is along Figure 1 The cross-sectional view obtained from line II-II'; Figure 3 yes Figure 2 An enlarged cross-sectional view of part A; and Figure 4 This is a schematic diagram illustrating an embodiment of a stacked structure of double-sided tape. Detailed Implementation

[0021] The features of the invention and methods of implementing said features can be more readily understood by referring to the following detailed description of preferred embodiments and accompanying drawings. However, the invention can be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art, and the invention will be defined only by the appended claims.

[0022] It should be understood that when a component or layer is referred to as being "on," "connected to," or "coupled" to another component or layer, the component or layer may be directly on or directly connected to the other component or layer, or directly on or directly connected to an intermediate component or layer. Conversely, when a component or layer is referred to as being "directly on," "directly connected to," or "directly coupled to" another component or layer, there is no intermediate component or layer. As used herein, "connected" can mean physically connected, electrically connected, and / or fluidly connected to each other.

[0023] Throughout the text, the same numbers refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0024] It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or portion from another. Therefore, without departing from the teachings of the invention, the first element, component, region, layer, or portion discussed below may be referred to as the second element, component, region, layer, or portion.

[0025] For ease of description, spatial relative terms, such as “below,” “under,” “below,” “above,” “up,” etc., may be used herein to describe the relationship of one element or feature to another, as illustrated in the accompanying drawings. It should be understood that, in addition to the orientations described in the drawings, spatial relative terms are intended to also include different orientations of the device in use or operation. For example, if the device in the drawings is flipped, an element described as “below” or “below” relative to other elements or features would be positioned “above” relative to those other elements or features. Thus, the exemplary term “below” can include both the upward and downward orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptive terms used herein shall be interpreted accordingly.

[0026] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural form, including “at least one,” unless the context clearly indicates otherwise. It should also be understood that, when used in this specification, the terms “comprise,” “comprising,” “include,” and / or “including” indicate the presence of the specified feature, integer, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, operations, elements, components, and / or groups thereof. “At least one” is not construed as limiting “a” or “an.” “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0027] As used herein, “about” or “approximately” includes the specified numerical value and indicates an acceptable deviation from the specified value as determined by a person skilled in the art, taking into account the relevant measurement and the error associated with the measurement of the specific quantity (i.e., the limits of the measurement system). For example, “about” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the specified value.

[0028] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It should also be understood that terms, such as those defined in commonly used dictionaries, shall be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and this disclosure, and shall not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0029] Exemplary embodiments are described herein with reference to cross-sectional views, which are schematic illustrations of idealized embodiments. Therefore, variations in the shape of the illustrations are expected due to factors such as manufacturing techniques and / or tolerances. Consequently, the embodiments described herein should not be construed as limited to the specific shapes of the regions illustrated herein, but should include deviations in shape resulting from factors such as manufacturing processes. For example, regions exemplified or described as planar may generally have rough and / or non-linear characteristics. Furthermore, acute angles in the examples may be rounded. Therefore, the regions exemplified in the figures are schematic in nature, and their shapes are not intended to illustrate precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0030] As used in this article, "acetoxy" refers to a group having the structural formula CH3COO-.

[0031] As used herein, "alkyl" refers to a straight-chain or branched, saturated monovalent hydrocarbon group (e.g., C14). 1-6 Alkyl groups, such as methyl or hexyl).

[0032] As used herein, “acrylic polymer” includes acrylic acid and (C) that can be optionally crosslinked. 10-30 alkyl) acrylate or (C 10-30 Homopolymers and copolymers of alkyl methacrylate units.

[0033] As used herein, "alkoxy" means an alkyl group (i.e., alkyl-O-) linked by oxygen, such as methoxy, ethoxy, and sec-butoxy groups.

[0034] As used in this article, "allyl" refers to a group having the structural formula H2C=CH-CH2-.

[0035] As used herein, "aromatic hydrocarbon" refers to hydrocarbons having aromatic rings, and includes monocyclic and polycyclic hydrocarbons, wherein the other rings of polycyclic hydrocarbons may be aromatic or non-aromatic. Specific aromatic hydrocarbons include benzene, naphthalene, toluene, and xylene.

[0036] As used herein, "aryl" refers to a monovalent group (e.g., C10) formed by removing a hydrogen atom from one or more rings of an aromatic hydrocarbon. 6-12 Aryl groups, such as phenyl or naphthyl groups.

[0037] As used in this article, "amino" refers to the formula -N(R) 1 )2 groups, wherein each R 1 Independently hydrogen, C 1-6 Alkyl or C 6-12 Aryl.

[0038] As used herein, “epoxyalkyl” means a group in which an epoxy group is incorporated into an alkyl group (such as the alkyl group described above).

[0039] As used in this article, "thiol" refers to a group containing a sulfur atom bonded to a hydrogen atom.

[0040] The implementation scheme will be described below with reference to the accompanying drawings.

[0041] Figure 1 This is a plan view showing the display device according to the embodiment.

[0042] refer to Figure 1The display device 1 includes a display panel 100. The display panel 100 is a panel for displaying a screen and includes a display area (“DA”) and a non-display area (“NA”) when viewed in a plan view. The display area DA is the area in which an image is seen, and the non-display area NA is the area in which an image is not seen. The non-display area NA may be formed, for example, outside the periphery of the display area DA.

[0043] The display panel 100 may have a generally rectangular shape when viewed in a plan view. For example, the display device 1 may have a rectangular shape having a pair of long sides in one direction X and a pair of short sides in another direction Y perpendicular to the X direction, such as... Figure 1 As shown.

[0044] The display device 1 can be a narrow-bezel display device with a narrow bezel, or it can be a frameless display device, wherein a top cover or top frame covering part of the top of the display panel 100 is omitted. Therefore, the non-display area NA can be arranged only in the smallest area when viewed in a plan view, and can be arranged, for example, not along one long side and a pair of short sides, but only along the other long side.

[0045] Double-sided tape 200 is disposed near the edge of the display device 1. Double-sided tape 200 may be disposed along one or more edges of the display device 1. Double-sided tape 200 may be disposed between the display panel 100 and the mold frame 300 in the display device 1.

[0046] Figure 2 It is along Figure 1 The cross-sectional view obtained from line II-II', and Figure 3 yes Figure 2 An enlarged cross-sectional view of part A.

[0047] refer to Figure 2 The display device 1 can be a curved display device having a predetermined curvature to achieve, for example, a curved display device used in monitors, TVs, and mobile devices with curved surfaces. In particular, the display device 1 can be a curved display device that has curvature only in one direction X when viewed in a planar view and has a curved shape only in a transverse section (e.g., view) in one direction X.

[0048] The display device 1 may have a constant curvature throughout all its cross sections, or it may have multiple different curvatures for each predetermined cross section. The display device 1 may have a concave curved shape when viewed from the outside as a screen displayed by the display panel 100.

[0049] Display device 1 includes a display panel 100 and a storage container 600 supporting the display panel 100. When the display panel 100 is a light-receiving element such as a liquid crystal display panel, the display device 1 may further include a backlight unit 700. The backlight unit 700 may include (e.g., fill) a portion or the entire storage container 600. When the display panel 100 is a self-emissive element such as an organic light-emitting display, the backlight unit 700 may be omitted and a separate storage container 600 may be provided. In the following description, the use of a liquid crystal display panel as the display panel 100 is illustrated, but the embodiments are not limited thereto.

[0050] The backlight unit 700 includes an optical component 400 and a storage container 600. The storage container 600 may include a base frame 500 and a mold frame 300.

[0051] Components such as the base frame 500, display panel 100, and mold frame 300 may also have curved shapes corresponding to the shape of the curved display device.

[0052] The base frame 500 can be arranged below the display device 1. The base frame 500 can have a plate shape, the plate shape having a bottom and side walls to accommodate the components constituting the display device 1. The base frame 500 receives the optical component 400.

[0053] The base frame 500 can be formed from metal materials, synthetic resin materials, etc., with a predetermined hardness.

[0054] The optical component 400 can be arranged on the base frame 500. The optical component 400 can be housed in a plate structure formed by the bottom and side walls of the base frame 500.

[0055] Although not shown in the accompanying drawings, optical component 400 may include a light source, a light guide plate, an optical sheet, a diffuser plate, etc., to provide light to the display panel 100 disposed on optical component 400. Examples of light sources may include light-emitting diodes (“LEDs”), and examples of optical sheets may include prism sheets, diffusers, microlenses, or reflective polarizers, but the embodiments are not limited thereto.

[0056] In an exemplary embodiment, the optical component 400 may be an edge-type optical component 400, wherein a plurality of light sources are arranged facing the side surface of the light guide plate and optical sheets are arranged between the light guide plate and the display panel 100, but the embodiment is not limited thereto.

[0057] The mold frame 300 can be arranged on the base frame 500 and the optical component 400. The mold frame 300 can be supported by the base frame 500, while receiving or supporting the display panel 100, and can prevent gaps from appearing on the optical component 400 arranged on the base frame 500.

[0058] The mold frame 300 may have a rectangular frame shape. The mold frame 300 may include sidewalls 310 and a base portion 320 that supports the display panel 100.

[0059] The mold frame 300 can be formed from a polymer material such as polycarbonate (“PC”) having predetermined stiffness and flexibility. Therefore, the mold frame 300 can be curved and arranged in a shape corresponding to the base frame 500 having curvature.

[0060] The display panel 100 can be arranged on the base frame 500 and the optical component 400. Specifically, the display panel 100 can be arranged on the base frame 500 and the optical component 400, and the edge of the display panel is supported by the base portion 320 of the mold frame 300. The edge of the display panel 100 can overlap with at least a portion of the base portion 320. The display panel 100 can be secured to the mold frame 300 using double-sided tape 200.

[0061] The display panel 100 may be a curved display panel with curvature, and the display device 1 may have a curved surface. That is, the display panel may be curved, having curvature in at least one direction, and the mold frame may be bent to correspond to the shape of the display panel.

[0062] The display panel 100 may include a first substrate 120 and a second substrate 130 disposed on the first substrate 120. A liquid crystal layer (not shown) may be inserted between the first substrate 120 and the second substrate 130. The display panel 100 may further include a polarizing element (not shown).

[0063] The first substrate 120 may be a substrate in which thin-film transistors (“TFTs”) are formed in a matrix as a switching device. Data lines and gate lines may be connected to the source and gate terminals of each TFT, respectively, and pixel electrodes made of conductive material may be connected to the drain terminals of the TFTs.

[0064] The second substrate 130 may be a substrate arranged opposite to the first substrate 120, and red, green, and blue (“RGB”) pixels for realizing (e.g., forming) colors may be formed in the second substrate in the form of a thin film. Suitable electrodes made of a conductive material may be formed in the second substrate 130 to face the pixel electrodes formed in the first substrate 120.

[0065] Double-sided tape 200 can be disposed between mold frame 300 and display panel 100. Double-sided tape 200 can be attached to mold frame 300 and display panel 100 via adhesive layers formed on its top and bottom portions. The portions of mold frame 300 and display panel 100 overlapping with double-sided tape 200 can be bent to have curvature, or can have a planar shape. The portions of mold frame 300 and display panel 100 overlapping with double-sided tape 200 are shown in the figures as having curvature, and double-sided tape 200 can therefore have a curved shape corresponding to the shape of mold frame 300 and display panel 100.

[0066] Shear stress and tensile stress can be applied between the display panel 100 and the mold frame 300 in the bending display device 1. Therefore, double-sided tape 200 is preferably inserted between the display panel 100 and the mold frame 300 so that it can withstand the shear stress and tensile stress described above, for example, without being torn. Double-sided tape 200 having such characteristics will be described in more detail.

[0067] Figure 4 This is a schematic diagram illustrating the stacking structure of double-sided tape according to an embodiment.

[0068] refer to Figure 4 The double-sided tape 200 includes a first adhesive layer 210, a foamed polymer layer 230, an interlayer polymer layer 240, and a second adhesive layer 220.

[0069] The first adhesive layer 210 and the second adhesive layer 220 are respectively disposed on the bottom and top layers of the double-sided tape 200. The first adhesive layer 210 and the second adhesive layer 220 can be attached to the upper surface of the base portion 320 of the mold frame 300 and the lower surface of the display panel 100, respectively.

[0070] The first adhesive layer 210 may contain a pressure-sensitive adhesive (“PSA”) as a major component.

[0071] PSA can be an acryloyl polymer, a silicone polymer, a polyester polymer, a rubber polymer, a polyurethane polymer, or a combination thereof.

[0072] In an exemplary embodiment, the PSA may include an acrylic copolymer, wherein the acrylic copolymer is formed by copolymerization with other monomers.

[0073] Examples of acrylic compounds may include, but are not limited to, acrylic monomers having 1 to 18 carbon atoms, and specific examples may include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isononyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.

[0074] Examples of other monomers that can copolymerize with acrylic compounds include, but are not limited to, styrene monomers, olefin monomers, vinyl esters, monomers containing cyano groups, monomers containing amide groups, monomers containing hydroxyl groups, monomers containing acidic groups, monomers containing epoxy groups, monomers containing amino groups, and monomers containing carboxyl groups.

[0075] The first adhesive layer 210 may further contain a coupling agent. The coupling agent can improve interfacial interaction by increasing the adhesion between the surface of the double-sided tape 200 and the surface of the display panel 100 or the mold frame 300, which are the adhered objects.

[0076] The coupling agent can be a silane coupling agent that can improve the adhesion between the display panel 100 made of glass material and the double-sided tape 200 made of polymer material.

[0077] The silane coupling agent may include a compound represented by the following formula 1.

[0078] Formula 1

[0079] In Equation 1, It can represent an amino group, an epoxy alkyl group, a mercapto group, or an allyl group.

[0080] In an exemplary implementation, - It can represent functional groups whose formulas are represented by -NH2, -CHOCH-, -SH, -CH=CH-CH3 or -CH2-CH=CH2.

[0081] Each OR can independently represent an alkoxy group or an acetoxy group. In an exemplary embodiment, -OR can represent a functional group whose formula is represented by -OCH3, -OC2H5, or -OCOCH3.

[0082] Based on 100 parts by weight of PSA, the amount of coupling agent contained in the first adhesive layer 210 can be from about 1 part by weight to about 2 parts by weight. When the amount of coupling agent is about 1 part by weight or more, the adhesion between the double-sided tape 200 and the adherend can be significantly improved, and when the amount is about 2 parts by weight or less, the weakening of the internal bonding force of the polymer constituting the adhesive layer can be effectively prevented.

[0083] The first adhesive layer 210 may further include a curing agent. The curing agent can be used to improve the bulk effect by enhancing the bonding force between polymers in the adhesive layer. In an exemplary embodiment, the curing agent can be used as a crosslinking agent for an acrylic copolymer (which is a PSA component).

[0084] The curing agent may be an isocyanate curing agent, and may particularly include toluene-2,4-diisocyanate or its derivatives represented by Formula 2.

[0085] Formula 2

[0086] Based on 100 parts by weight of PSA, the amount of curing agent contained in the first adhesive layer 210 can be from about 6 parts by weight to about 7 parts by weight. When the amount of curing agent is about 6 parts by weight or more, the bonding force between the polymers in the adhesive layer can be significantly improved, and when the amount is about 7 parts by weight or less, the weakening of the adhesion between the adhesive layer and the adherend can be effectively prevented.

[0087] The first adhesive layer 210 may be formed in a color that substantially blocks the transmission of light such as black, gray or white to block light leakage, or may further contain light absorbers such as carbon black (“P”) or pigments.

[0088] In an exemplary embodiment, based on 100 parts by weight of PSA, the amount of carbon black P contained in the first adhesive layer 210 can be from about 0.1 parts by weight to about 0.18 parts by weight. Therefore, the optical density OD calculated by Equation 1 can be about 5 or greater than 5.

[0089] Equation 1

[0090] In Equation 1, A represents the optical density OD, P0 represents the light intensity before the light passes through the object, and It indicates the intensity of light transmitted through an object.

[0091] When the amount of carbon black is about 0.1 parts by weight or more, the light absorption capacity of the first adhesive layer 210 can be improved to effectively block light leakage, and when the amount of carbon black is about 0.18 parts by weight or less, the weakening of the adhesive strength of the double-sided tape 200 can be prevented by ensuring a sufficient amount of the adhesive-related components.

[0092] The first adhesive layer 210 may have a crosslinking degree of about 40% to about 49% by weight among the PSA components, such as acrylic copolymers.

[0093] The second adhesive layer 220 may have the same material, composition and physical properties as the first adhesive layer 210 described above.

[0094] A foamed polymer layer 230 is disposed on the first adhesive layer 210. The foamed polymer layer 230 is a layer containing a foamable polymer such as polyurethane, and can be used to provide sufficient impact resistance to the double-sided tape 200 and prevent light leakage.

[0095] The foamed polymer layer 230 may comprise polyurethane foam (e.g., polyurethane foam), polystyrene foam, or a combination thereof.

[0096] The density of the foamed polymer layer 230 can be approximately 0.36 g / cm³. 3 To approximately 0.6 g / cm 3 The density of the foamed polymer layer 230 is related to the tensile strength of the double-sided tape 200, and the double-sided tape exhibits optimal physical properties within the aforementioned density range. When the density is approximately 0.36 g / cm³... 3 Or greater than 0.36 g / cm 3 At this time, the tensile strength of double-sided tape 200 can be significantly improved, and when the density is about 0.6 g / cm³, it can be further improved. 3 or less than 0.6 g / cm 3 This can prevent side effects imposed when achieving the curvature of a curved display device.

[0097] In the implementation scheme, the double-sided tape may have a strength of approximately 15.47 kgf / inch, measured 24 hours after the double-sided tape is attached to the mold frame and display panel. 2 ) or greater than 15.47 kgf / inch 2 The vertical ultimate tensile strength, for example, was approximately 15.47 kgf / inch, measured 24 hours after double-sided tape was applied to the mold frame and display panel. 2 Approximately 16.33 kgf / inch 2 The vertical ultimate tensile strength.

[0098] In the implementation, the double-sided tape may have a strength of approximately 12.8 kgf / inch, measured 30 minutes after the double-sided tape is attached to the mold frame and display panel. 2 or greater than 12.8 kgf / inch 2 The horizontal ultimate tensile strength, for example, is approximately 12.8 kgf / inch, measured 30 minutes after the double-sided tape was attached to the mold frame and display panel. 2 Approximately 13.5 kgf / inch 2 The horizontal ultimate tensile strength.

[0099] The foamed polymer layer 230 can be formed in colors such as black, gray, white, etc., or can further contain light absorbers such as carbon black, pigments, etc., such that the optical density OD calculated by Equation 1 is about 5 or greater than 5.

[0100] A sandwich polymer layer 240 is disposed on the foamed polymer layer 230. When the double-sided tape 200 is removed to reuse the display panel 100, the sandwich polymer layer 240 can be applied to easily remove any residue of the double-sided tape 200 remaining on the surface of the display panel 100.

[0101] The interlayer polymer layer 240 may comprise a thermoplastic resin, such as a polyolefin (“PO”), polyethylene terephthalate (“PET”), and polyester, or a combination thereof. Examples of PO may include polyethylene (“PE”), polypropylene (“PP”), etc.

[0102] The interlayer polymer layer 240 can be formed in colors such as black, gray, white, etc., or can further contain light absorbers such as carbon black or pigments, such that the optical density OD calculated by Equation 1 is about 5 or greater than 5.

[0103] In the double-sided tape 200 according to the embodiment, the foamed polymer layer 230 may have a thickness of about 0.3 mm to about 1.15 mm, the interlayer polymer layer 240 may have a thickness of about 0.045 mm to about 0.055 mm, each of the first adhesive layer 210 and the second adhesive layer 220 may have a thickness of about 0.05 mm to about 0.1 mm, and the total thickness of the double-sided tape 200 may be about 0.4 mm to about 1.3 mm.

[0104] When the total thickness of the double-sided tape 200 is less than about 0.4 mm, the double-sided tape 200 may have difficulty withstanding (e.g., without being torn) 500 hours or more in an environment of 65 °C and 90% humidity when applied to a curved display device 1 with a curvature of about 1,000 R. However, when the thickness is about 1.3 mm or greater, the double-sided tape can withstand (e.g., without being torn) 500 hours or more under the same conditions.

[0105] However, the implementation is not limited to this, and the thickness of each layer contained in the double-sided tape 200 can be appropriately changed as needed.

[0106] As described above, the double-sided tape 200 is formed by combining components such as the coupling agent, curing agent, carbon black, and dense foamed polymer layer 230 described above. Compared with conventional double-sided tape, it can significantly improve the adhesion and tensile strength relative to the adhered object, effectively block light leakage, and the double-sided tape can bond and fix to the adhered object. At the same time, even when applied to a curved display device with a curvature of about 600 R to about 4,000 R, it can withstand (e.g., without being torn during the process) the stress generated between the display panel 100 and the mold frame 300.

[0107] Further details regarding the implementation scheme will be described with reference to the following specific preparation and experimental examples, and any content not described herein can be fully inferred by those skilled in the art and is therefore omitted from description.

[0108] Example

[0109] Preparation of double-sided tape

[0110] Preparation Example 1

[0111] Multiple double-sided tapes were prepared for use in the experiments described later, wherein a first adhesive layer, a white foamed polymer layer containing polyurethane foam, a sandwich polymer layer containing PET, and a second adhesive layer were stacked in sequence.

[0112] The first adhesive layer and the second adhesive layer are formed to comprise an acrylic copolymer, a silane coupling agent (1 part by weight, based on 100 parts by weight of the acrylic copolymer), toluene-2,4-diisocyanate (6 parts by weight, based on 100 parts by weight of the acrylic copolymer), and carbon black (0.15 parts by weight, based on 100 parts by weight of the acrylic copolymer).

[0113] Preparation Example 2

[0114] Multiple double-sided tapes were prepared in the same manner as in Preparation Example 1, but the foamed polymer layer was formed in black.

[0115] Experiments on the properties of double-sided tape

[0116] Experimental Example 1

[0117] To test the tensile properties of the double-sided tape prepared in Example 1, a vertical tensile test was performed on the double-sided tape as follows.

[0118] Three double-sided adhesive tapes of Preparation Example 1 were prepared and cut into 1-inch × 1-inch areas. The double-sided adhesive tapes were attached to a first adhesive layer and a second adhesive layer, such that the first and second adhesive layers were in contact with the PC board and the glass plate, respectively, and cured for 24 hours (hr). A base was fixed to the opposing surfaces of the PC board and the glass plate with the double-sided adhesive tapes attached using strong adhesive, and the tensile strength of the double-sided adhesive tapes was measured by pulling the base vertically at a speed of 10 mm / min using an Instron testing machine.

[0119] As a comparative example, the same experiment as above was conducted using foamed tape prepared by 3M (Comparative Example 1).

[0120] As a result of the experiment, the foamed tape of Comparative Example 1 was torn after being stretched for a certain period of time, while the maximum adhesive force of the double-sided tape of Preparation Example 1 could not be measured because the adhesive fixed to the base detached (e.g., became unadhesive) before the double-sided tape was torn. Table 1 summarizes the tensile strength (ultimate tensile strength) of the double-sided tape of Preparation Example 1 measured just before the adhesive fixed to the base detached (e.g., became unadhesive), and the tensile strength (ultimate tensile strength) measured just before the foamed tape of Comparative Example 1 was torn.

[0121] Table 1

[0122] Experimental Example 2

[0123] To test the tensile properties of the double-sided adhesive tapes of Preparation Example 1 and Preparation Example 2, a horizontal tensile test was performed on the double-sided adhesive tapes as follows.

[0124] For each of Preparation Examples 1 and 2, three double-sided adhesive tapes were prepared and cut to have an area of ​​50 mm × 25 mm. A PC sheet was attached to the side of the first adhesive layer of each double-sided adhesive tape, such that its attachment area was 25 mm × 25 mm, and after being pressed twice with a weight of 2 kg, it was cured at room temperature for 30 minutes. The portion of the double-sided adhesive tape not attached to the PC sheet was then secured so that the double-sided adhesive tape and the PC sheet were perpendicular to the ground, and then a weight of 1 kg was attached to the PC sheet to transfer the horizontal tensile force to the double-sided adhesive tape. The experimental environment was maintained at 85 °C and 85% humidity.

[0125] As comparative examples, the same experiments as described above were conducted using three sheets of each of two types of foamed tapes prepared by 3M (Comparative Example 2 and Comparative Example 3).

[0126] As a result of the experiment, the foamed tapes of Comparative Example 2 and Comparative Example 3 were torn after a certain period of time, while the double-sided tapes of Preparation Example 1 and Preparation Example 2 maintained their adhesive strength for at least 4 hours. Table 2 summarizes the measured retention time of each tape and the average retention time of each of the examples and comparative examples.

[0127] Table 2

[0128] Experimental Example 3

[0129] To test the tensile properties of the double-sided adhesive tapes prepared in Example 1 and Example 2, horizontal tensile tests were performed on the double-sided adhesive tapes in different ways as follows.

[0130] For each of Preparation Examples 1 and 2, two double-sided adhesive tapes were prepared and cut to have an area of ​​25 mm × 25 mm. Each double-sided adhesive tape was attached to a first adhesive layer and a second adhesive layer, such that the first adhesive layer and the second adhesive layer were in contact with the PC board and the glass plate, respectively, and then cured at room temperature for 30 minutes after being pressed twice with a weight of 2 kg. The PC board was then fixed, and the glass plate was pulled horizontally at a speed of 1 mm / min using an Inström testing machine to measure its tensile strength and elongation.

[0131] As a comparative example, the same experiment as above was conducted using two foamed tapes prepared by 3M (Comparative Example 4).

[0132] As a result of the experiment, the ultimate tensile strength (which is the tensile strength just before the tape is torn) and stretch distance of Preparation Examples 1 and 2 are significantly better than those of the double-sided tape of Comparative Example 4. Table 3 summarizes the tensile strength (ultimate tensile strength) and stretch distance measured just before each tape was torn in each of the Preparation Examples and Comparative Examples, as well as the average values ​​of the ultimate tensile strength and the measured stretch distance.

[0133] Table 3

[0134] Experiment Example 4

[0135] To test the adhesion retention performance, when the double-sided tape of Preparation Example 1 was applied to a curved display device, an accelerated test was performed on the double-sided tape as follows.

[0136] Ten display device models were fabricated by attaching a 34-inch (34") 0.4 mm thick (0.4 t) glass plate with a curvature of 1,000 R to a mold frame fixed to the backlight unit using double-sided adhesive tape of Preparation Example 1. The double-sided tape was attached at positions 4 mm from the light-facing portion, 4.5 mm from the incident light portion, and 2.5 mm from the right / left edges. Additionally, five additional display device models were fabricated in the same manner, but with glass plates having a curvature of 1,200 R. The condition of the samples was then observed over time under conditions of 65 °C and 90% humidity.

[0137] As a comparative example, each of the tapes prepared by NITTO, TAPEX, and 3M was used to prepare 1,000 R and 1,200 R models in the same manner as described above, and the same experiments as described above were performed on them.

[0138] As a result of the experiment, most of the 1,000 R and 1,200 R models using the double-sided tape of Preparation Example 1 maintained their adhesion and durability even after 1,000 hours, as shown in Table 4, while the 1,000 R model using the comparative double-sided tape was damaged after 216 hours, as shown in Table 5.

[0139] Table 4

[0140] Table 5

[0141] Experimental Example 5

[0142] To evaluate the adhesive properties of double-sided tape based on the use of silane coupling agents, a horizontal tensile test was performed on the double-sided tape as follows.

[0143] Six double-sided tapes of Preparation Example 1 were prepared. Each double-sided tape was attached to a glass plate with a width of 25 mm, such that the glass plate faced the second adhesive layer of the double-sided tape. Three double-sided tapes were cured at room temperature for 20 minutes, while the remaining three were cured at 60 °C for 24 hours.

[0144] Subsequently, when the double-sided tape was fixed to the glass plate, the tensile strength was measured when the glass plate was pulled horizontally at a speed of 300 mm / min.

[0145] For Comparative Example 5, six double-sided tapes prepared in the same manner as in Preparation Example 1, but without the addition of the silane coupling agent, were used to conduct the same experiments as described above.

[0146] As a result of the experiment, the tensile strength (in Newtons / 25 mm) just before the double-sided tape was torn is summarized in Table 6. The double-sided tape of Preparation Example 1, which contained silane coupling agent and was cured at 60 °C for 24 hours, showed significantly better adhesive properties than the double-sided tape of Comparative Example 5, which did not contain silane coupling agent.

[0147] Table 6

[0148] According to the implementation scheme, by applying components such as coupling agents, curing agents, carbon black, and dense foamed polymer layers to the double-sided tape, the adhesion and tensile strength of the double-sided tape relative to the adhered object can be significantly improved, light leakage can be effectively blocked, and the double-sided tape can be attached and fixed between the display panel and the mold frame, while also withstanding (e.g., not being torn during bending) the stress generated between the display panel and the mold frame, even when applied to a bent display device.

[0149] The effects of the implementation scheme are not limited to those exemplified above, and many more effects are included in the specification.

[0150] Although the invention has been specifically exemplified and described with reference to exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined in the claims. Exemplary embodiments should be considered for descriptive purposes only and not for limiting purposes.

Claims

1. A double-sided adhesive tape disposed between a curved display panel having curvature in at least one direction and a curved mold frame having a shape corresponding to the display panel, and configured to secure the display panel and the mold frame to each other, the double-sided adhesive tape comprising: The first adhesive layer comprises 100 parts by weight of an acrylic polymer, 1 to 2 parts by weight of a silane coupling agent and 0.1 to 0.18 parts by weight of carbon black, and the first adhesive layer has a crosslinking degree of 40% to 49% by weight and an optical density of 5 or greater than 5. A foamed polymer layer is disposed directly on the first adhesive layer. The foamed polymer layer is a white foamed polymer layer containing polyurethane foam but not containing carbon black and pigment. The foamed polymer layer has an optical density of 5 or greater and a thickness of 0.3 mm to 1.15 mm. A sandwich polymer layer, disposed directly on the foamed polymer layer, the sandwich polymer layer comprising polyolefin, polyester, or a combination thereof, the sandwich polymer layer having an optical density of 5 or greater and a thickness of 0.045 mm to 0.055 mm; and A second adhesive layer, disposed directly on the interlayer polymer layer, comprises 100 parts by weight of acrylic polymer, 1 to 2 parts by weight of silane coupling agent, and 0.1 to 0.18 parts by weight of carbon black. The second adhesive layer has a crosslinking degree of 40% to 49% by weight and an optical density of 5 or greater. The total thickness of the double-sided tape is 0.4 mm to 1.3 mm. The curvature of the curved display panel is said to be between 600 R and 4,000 R. The silane coupling agent mentioned above includes compounds represented by Formula 1: Formula 1 In Equation 1, The OR indicates functional groups represented by -NH2, -SH, -CH=CH-CH3, or -CH2-CH=CH2, and each OR independently represents a functional group represented by -OCH3, -OC2H5, or -OCOCH3. When measured 24 hours after the double-sided tape was attached to the mold frame and the display panel, the double-sided tape had a vertical ultimate tensile strength of 15.47 kgf / square inch or greater.

2. The double-sided tape as claimed in claim 1, wherein the polyester is polyethylene terephthalate.

3. The double-sided tape of claim 1, wherein the first adhesive layer, the second adhesive layer, or a combination thereof further comprises an isocyanate curing agent.

4. The double-sided tape as claimed in claim 3, wherein the isocyanate curing agent comprises toluene-2,4-diisocyanate or a derivative thereof.

5. The double-sided tape of claim 3, wherein, based on 100 parts by weight of the acrylic polymer, the first adhesive layer, the second adhesive layer, or a combination thereof comprises 6 to 7 parts by weight of the isocyanate curing agent.

6. The double-sided tape of claim 1, wherein the foamed polymer layer has a density of 0.36 g / cm³ to 0.6 g / cm³.

7. The double-sided tape of claim 1, wherein, when measured 30 minutes after the double-sided tape is attached to the mold frame and the display panel, the double-sided tape has a horizontal ultimate tensile strength of 12.8 kgf / square inch or greater than 12.8 kgf / square inch.

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