Background

The present invention relates to a double-sided adhesive tape.

Recently, with the development of technology, electronic products such as televisions, computers, and mobile terminals have been widely used. Here, a mobile terminal is an electronic product capable of implementing various applications as well as wireless communication including voice calls, SNS, and the Internet, and may include a mobile phone which is commonly referred to as a smartphone, a PDA, or the like.

As electronic products such as televisions, computers, and mobile terminals are high-functionalized to meet the needs of users, it is common to include a display panel that functions as an interface or a touch panel for displaying a screen to the user. In such a display panel, a rigid display has been developed in the related art, but in recent years, a foldable display to be folded or a reliable display to be rolled has been actively developed.

Meanwhile, in the case of the foldable display or the reliable display, a double sided adhesive tape (or double-sided coated tape) may be used for adhesion with other components. Such a double-sided adhesive tape needs to be designed to bond the display to other components, but be folded or rolled according to its characteristics. Accordingly, there is a need for a double-sided adhesive tape capable of bonding a foldable or reliable display to other components without deteriorating an adhesive strength when folded or rolled.

Summary

However, when the double-sided adhesive tape used to bond the foldable or reliable display to other components is folded or rolled due to its characteristics, a stress is applied to the inside of the tape. At this time, if the stress applied to the double-sided adhesive tape is not properly reduced, there may be a problem that the adhesive strength is lowered or the double-sided adhesive tape is broken.

Embodiments of the present invention are invented with the above background, and an object of the present invention is to provide a double-sided adhesive tape capable of bonding a foldable or reliable display to other components without deteriorating an adhesive strength when folded or rolled. In addition, the present invention is to provide a double-sided adhesive tape capable of adequately reducing a stress applied to the double-sided adhesive tape when the double-sided adhesive tape is folded or rolled.

According to an aspect of the present invention, there is provided a double-sided adhesive tape which may be used for a reliable or foldable display, the double-sided adhesive tape including: a plurality of adhesive parts, a plurality of curing parts having a greater modulus than the adhesive parts, and a pressure-sensitive adhesive layer extending in a width direction, wherein the plurality of adhesive parts and the plurality of curing parts are alternately arranged in the width direction.

According to the embodiments of the present invention, it is possible to bond a foldable or reliable display to other components without deteriorating an adhesive strength when folded or rolled.

In addition, it is possible to adequately reduce a stress applied to the double-sided adhesive tape when the double-sided adhesive tape is folded or rolled.

Brief Description of the Drawings

FIG. 1 is a cross-sectional perspective view of a double-sided adhesive tape according to an embodiment of the present invention.

FIG. 2 is a front view of FIG. 1.

FIG. 3 is a cross-sectional view of FIG. 1 taken along line A-A\

FIG. 4 is a diagram illustrating a state in which a pressure-sensitive adhesive layer of FIG. 1 is bonded to a display.

FIG. 5 is a diagram illustrating a state in which the pressure-sensitive adhesive layer of FIG. 3 and the display are rolled.

FIG. 6 is a diagram illustrating an adhesive strength of the pressure-sensitive adhesive layer before and after UV curing.

Detailed Description

Hereinafter, specific embodiments for implementing the spirit of the present invention will be described in detail with reference to the accompanying drawings.

Moreover, in describing the present invention, a detailed description of related known configurations or functions will be omitted when it is determined to make the gist of the present invention blur. In addition, when it is mentioned that a certain component is ‘disposed’ or ‘bonded’ to the other component, it should be understood that the component may be disposed or bonded directly to the other component, but other components may also exist therebetween.

Terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. A singular form may include a plural form unless otherwise explicitly meant in the context.

Further, in the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated, and the size of each component does not entirely reflect an actual size.

Terms including ordinal numbers, such as first and second, may be used for describing various components, but the corresponding components are not limited by these terms. The terms are used only to distinguish one component from other components.

The term “comprising” used in the specification means that a specific feature, region, integer, step, operation, element and/or component is embodied, but presence or addition of other specific features, regions, integers, steps, operations, elements, components, and/or groups is not excluded.

Meanwhile, in this specification, a width direction may be an x-axial direction in FIGS. 1 and 2, and a thickness direction may be a z-axial direction in FIGS. 1 and 2. In addition, a length direction may be a y-axial direction in FIGS. 1 and 3. In addition, in this specification, the expressions of a width direction, a length direction, a thickness direction, and the like are described based on the illustration in the drawings, and it is noted in advance that the expressions may be varied when a direction of the corresponding object is changed.

Hereinafter, a specific configuration of a double-sided adhesive tape 1 according to an embodiment of the present invention will be described with reference to the drawings.

Hereinafter, referring to FIG. 1, the double-sided adhesive tape 1 according to an embodiment of the present invention may be used for adhesion between components of an electronic product. For example, the double-sided adhesive tape 1 may be used for televisions, computers, and smartphones, and may be used for bonding a display panel to another electronic component 2. In addition, the double-sided adhesive tape 1 may be configured to be bent or folded while providing an adhesive strength. As a more detailed example, the double-sided adhesive tape 1 may be used to bond a foldable display to be folded or a Tollable display to be rolled to another electronic component 2. Here, the foldable display and the Tollable display are displays to be rolled or folded, and are different from a flexible display to be simply bent. In addition, the double-sided adhesive tape 1 may include, for example, a pressure sensitive adhesive (PSA) tape. In addition, the double-sided adhesive tape 1 may have a thickness of 4 pm or more and 55 pm or less. This double-sided adhesive tape 1 may include a pressure-sensitive adhesive layer 100 and a release layer 200.

Referring to FIG. 2, the pressure-sensitive adhesive layer 100 may be a portion that provides the adhesive strength of the double-sided adhesive tape 1. In addition, the pressure-sensitive adhesive layer 100 may include a material of which properties are changed when cured by UV rays. The pressure-sensitive adhesive layer 100 has a low storage modulus before being cured by UV rays, but has a high storage modulus when cured by UV rays. As a result, the pressure-sensitive adhesive layer 100 has a high adhesive strength before being cured by UV rays, but has a decreased adhesive strength when cured by UV rays. For example, the pressure-sensitive adhesive layer 100 may include an adhesive composition including a base polymer, a crosslinking agent reacting with the base polymer, a curable resin, and an initiator curing the curable resin.

The base polymer may provide an adhesive strength as a main component of the adhesive composition. Such a base polymer may react with the crosslinking agent to form a film or the like, and may react with the crosslinking agent before the curable resin is cured by an initiator. The base polymer may contain functional groups which are reactive with the crosslinking agent. For example, the base polymer may have at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an acryl group, a methacryl group, an acetate group, and a vinyl group.

In addition, the base polymer may have an acrylate-based functional group. Accordingly, the base polymer may provide a high modulus and a lower adhesive strength by causing crosslinking even between the acrylate-based functional groups by a radical reaction during UV curing to form an interpenetrated network structure with a cured chain of a first oligomer. In addition, a type of the acrylate-based functional group may be an acrylate functional group or a methacrylate functional group. As another example, the base polymer may be an acrylic resin. In other words, the base polymer may be an acrylic resin having an acrylate-based functional group.

As another example, the base polymer may be a thermosetting resin. The base polymer may be a PSA resin.

The curable resin may include a first oligomer, a second oligomer, and an organic acid, and may be cured when irradiated with UV rays. Such a curable resin may be UV cured after the reaction of the base polymer and the crosslinking agent.

The initiator may include a photoinitiator and may cure the curable resin. For example, the photoinitiator may include one or more of ketones (benzophenone, acetophenone, etc.), benzoins, benzoin ethers, benzyls and benzyl ketals.

The crosslinking agent reacts with the base polymer to form a film and the like.

Meanwhile, UV curing may be performed on a part of the pressure-sensitive adhesive layer 100 to change properties of a part of the pressure-sensitive adhesive layer 100. For example, the pressure-sensitive adhesive layer 100 may be UV-cured at a temperature of - 20°C. In addition, UV rays may be irradiated using a mask in which holes are formed so as to have a predetermined pattern in the pressure-sensitive adhesive layer 100. In this case, UV rays are irradiated to the pressure-sensitive adhesive layer 100 corresponding to a portion where the holes are formed to perform UV curing, and the UV rays may not be irradiated to the pressure-sensitive adhesive layer 100 corresponding to a portion where the holes are not formed. Accordingly, the pressure-sensitive adhesive layer 100 may be irradiated with UV rays to have a predetermined pattern, and the pressure- sensitive adhesive layer 100 may be divided into portions having different characteristics within one layer. In addition, the pressure-sensitive adhesive layer 100 may have a thickness of 3 pm or more and 50 pm or less. The pressure-sensitive adhesive layer 100 may include an adhesive part 110 and a curing part 120.

The adhesive part 110 is a portion of the pressure-sensitive adhesive layer 100 that is not UV-cured, and may have a modulus different from that of the curing part 120. For example, the adhesive part 110 may have a modulus of 10 ⁴ Pa or more and 5 x 10 ⁵ Pa or less. In addition, the adhesive part 110 may have a higher adhesive strength than that of the curing part 120. For example, the adhesive part 110 may have an adhesive strength of 300 gf/in or more and 2,000 gf/in or less. In addition, a plurality of adhesive parts 110 may be provided. In addition, the width of the adhesive part 110 may be provided in a range of 0.001 mm or more and 5 mm or less. As a more detailed example, the width of the adhesive part 110 may be 10 pm or more and 100 pm or less. Meanwhile, referring to FIG. 3, the adhesive part 110 may extend in a length direction so as to have the same length as the pressure-sensitive adhesive layer 100.

The curing part 120 may be a portion of the pressure-sensitive adhesive layers 100 that is cured by UV rays, and may have different properties before UV curing. The curing part 120 may have a greater modulus than the adhesive part 110. In addition, the curing part 120 may include a material that has the same modulus as the adhesive part 110 before UV curing. For example, the material may include an adhesive composition having a radical functional group. In addition, the curing part 120 may have a modulus of 10 ⁶ Pa or more and 10 ⁷ Pa or less, and may have a modulus of 10 ⁴ Pa or more and 5 x 10 ⁵ Pa or less before UV curing. The curing part 120 may include the same composition as the adhesive part 110. Meanwhile, the curing part 120 may extend in a length direction so as to have the same length as the pressure-sensitive adhesive layer 100.

In addition, the curing part 120 may have a lower adhesive strength than the adhesive part 110, and may have the same adhesive strength as the adhesive part 110 before UV curing. For example, the curing part 120 may have an adhesive strength of 0 gf/in or more and 10 gf/in or less, and may have an adhesive strength of 300 gf/in or more and 2,000 gf/in or less before UV curing. In addition, a plurality of curing parts 120 may be provided. In addition, the width of the curing part 120 may be provided in a range of 0.001 mm or more and 5 mm or less. As a more detailed example, the width of the curing part 120 may be 10 pm or more and 100 pm or less. In addition, the curing part 120 may have the same width and thickness as the adhesive part 110. The curing part 120 may include the same material as the adhesive part 110.

On the other hand, the adhesive parts 110 and the curing parts 120 may be arranged alternately with each other. Further, the adhesive parts 110 and the curing parts 120 are arranged alternately with each other, so that the pressure-sensitive adhesive layer 100 may have a characteristic in which a modulus increases and then decreases in one direction. As described above, since the modulus of the pressure-sensitive adhesive layer 100 is repeatedly changed in a width direction, deformation of the pressure-sensitive adhesive layer 100 may be minimized when the pressure-sensitive adhesive layer 100 is folded or rolled. In addition, by minimizing the deformation of the pressure-sensitive adhesive layer 100, the stress applied to the pressure-sensitive adhesive layer 100 may be reduced.

Further, the adhesive parts 110 and the curing parts 120 are arranged alternately with each other, so that the pressure-sensitive adhesive layer 100 may have a characteristic in which an adhesive strength increases and then decreases in a width direction. As described above, since the pressure-sensitive adhesive layer 100 is provided so that the adhesive strength is repeatedly changed in the width direction, even if the pressure- sensitive adhesive layer 100 is folded or rolled, adhesion between the display and the electronic component 2 may be maintained. For example, the pressure-sensitive adhesive layer 100 does not need to be divided into an adhesive area that is bonded to the electronic component 2 and a non-adhesive area that is not bonded thereto, and may be provided without the need to separately remove the pressure-sensitive adhesive layer 100 corresponding to the non-adhesive area.

The adhesive parts 110 and the curing parts 120 may be continuously arranged in each other, and may be formed integrally and may be formed continuously within one layer. In addition, the adhesive part 110 and the curing part 120 may be configured so that, for example, an interval between the center of the adhesive part 110 and the center of the curing part 120 is 1 pm or more and 500 pm or less. As a more detailed example, the adhesive part 110 and the curing part 120 may be configured so that an interval between the center of the adhesive part 110 and the center of the curing part 120 is 10 pm or more and 100 pm or less.

The release layer 200 may protect an adhesive strength of the pressure-sensitive adhesive layer 100. In other words, the release layer 200 may protect the adhesive strength of the pressure-sensitive adhesive layer 100 by preventing one surface of the pressure- sensitive adhesive layer 100 from contacting other objects. In addition, the release layer 200 may have a light blocking property. Since the release layer 200 has the light blocking property, it is possible to prevent the pressure-sensitive adhesive layer 100 from being exposed to unnecessary UV rays, and to prevent the properties of the pressure-sensitive adhesive layer 100 from changing. For example, the release layer 200 may include one or more of a polyethylene (PE) fdm, a polyester (PET) fdm, and a polypropylene (PP) fdm. In addition, the release layer 200 may have a thickness of 1 pm or more and 5 pm or less. Such a release layer 200 may include a first release layer 210 and a second release layer 220

The first release layer 210 may be disposed on one surface of the pressure-sensitive adhesive layer 100 to protect the adhesive strength of one surface of the pressure-sensitive adhesive layer 100. In addition, the second release layer 220 may be disposed on the other surface of the pressure-sensitive adhesive layer 100 to protect the adhesive strength of the other surface of the pressure-sensitive adhesive layer 100. In other words, since the pressure-sensitive adhesive layer 100 is disposed between the first and second release layers 210 and 220, the adhesive strength of the pressure-sensitive adhesive layer 100 may be preserved.

Hereinafter, the operation and effect of the double-sided adhesive tape 1 according to an embodiment of the present invention will be described.

Referring to FIG. 4, a user may use the double-sided adhesive tape 1 for adhesion between electronic components 2. First, after removing the first release layer 210 and the second release layer 220 from the double-sided adhesive tape 1, one side of the double sided adhesive tape 1 and the electronic component 2 may be bonded to each other. For example, the electronic component 2 may be a foldable display or a reliable display. Such a double-sided adhesive tape 1 may be used while being rolled together with the electronic component 2, as illustrated in FIG. 5.

As such, the double-sided adhesive tape 1 according to an embodiment of the present invention may be used for adhesion between the foldable display or the reliable display and another electronic component 2.

In addition, the pressure-sensitive adhesive layer 100 is partially UV-cured to be provided so that the modulus of the pressure-sensitive adhesive layer 100 is repeatedly changed in the width direction. Accordingly, when the pressure-sensitive adhesive layer 100 is folded or rolled, there are effects of minimizing the deformation of the pressure- sensitive adhesive layer 100 and reducing the stress applied to the pressure -sensitive adhesive layer 100.

Also, the double-sided adhesive tape 1 may be irradiated with UV rays before being used. Referring to FIG. 6, it can be seen that the pressure-sensitive adhesive layer 100 of the double-sided adhesive tape 1 has a high adhesive strength before UV curing and a low adhesive strength after UV curing. As described above, since the pressure-sensitive adhesive layer 100 is provided so that the adhesive strength is repeatedly changed in the width direction, there is an effect that the pressure-sensitive adhesive layer 100 is divided into an adhesive area and a non-adhesive area, so that the non-adhesive area does not need to be removed. Therefore, there are effects of reducing costs when manufacturing the pressure-sensitive adhesive layer 100, and simplifying the process.

The embodiments of the present invention are listed as follows.

Item 1 is a double-sided adhesive tape which may be used for a reliable or foldable display, the double-sided adhesive tape including: a plurality of adhesive parts, a plurality of curing parts having a greater modulus than the adhesive parts, and a pressure-sensitive adhesive layer extending in a width direction, wherein the plurality of adhesive parts and the plurality of curing parts are arranged alternately with each other in the width direction.

Item 2 is the double-sided adhesive tape, wherein the pressure-sensitive adhesive layer is provided so that an interval between the center of the adhesive part and the center of the curing part is 10 pm or more and 100 pm or less.

Item 3 is the double-sided adhesive tape, wherein the adhesive part and the curing part extend in a length direction to have the same length as the pressure-sensitive adhesive layer.

Item 4 is the double-sided adhesive tape, wherein the curing part includes a radical functional group to have the same modulus as the adhesive part before curing.

Item 5 is the double-sided adhesive tape, wherein the adhesive part has a modulus of 10 ⁴ Pa or more and 5 x 10 ⁵ Pa or less, and the curing part has a modulus of 10 ⁶ Pa or more and 10 ⁷ Pa or less.

Item 6 is the double-sided adhesive tape, wherein the adhesive part and the curing part include the same composition as each other.

Item 7 is the double-sided adhesive tape, wherein the curing part has a lower adhesive strength than the adhesive part.

Item 8 is the double-sided adhesive tape, wherein the adhesive part has an adhesive strength of 300 gf/in or more and 2,000 gf/in or less, the curing part has an adhesive strength of 0 gf/in or more and 10 gf/in or less, and the curing portion includes a material having the same adhesive strength as the adhesive part before curing.

Item 9 is the double-sided adhesive tape, wherein the adhesive part and the curing part have the same thickness and width as each other. Item 10 is the double-sided adhesive tape, wherein the adhesive part and the curing part have a thickness of 3 pm or more and 50 pm or less.

Item 11 is the double-sided adhesive tape further including a release layer which includes one or more of a polyethylene (PE) fdm, a polyester (PET) film, and a polypropylene (PP) film and is disposed on at least one surface of the pressure-sensitive adhesive layer.

Item 12 is the double-sided adhesive tape, wherein the double-sided adhesive tape has a thickness of 3 pm or more and 50 pm or less.

Item 13 is the double-sided adhesive tape, wherein the plurality of adhesive parts and the plurality of curing parts are arranged without gaps from each other.

While the embodiments of the present invention have been described as specific examples, this is merely illustrative and it should be understood that the present invention is not limited thereto and has a widest range according to basic spirit disclosed in the present specification. Those skilled in the art may implement a pattern having a non- described shape by combining/substituting the disclosed examples, but this does not also depart from the scope of the present invention. Besides, it is apparent that those skilled in the art may easily change or modify the examples disclosed based on the present specification and these changes or modifications also belong to the scope of the present invention. 1: Double-sided adhesive tape 100: Pressure-sensitive adhesive layer

110: Adhesive part 120: Curing part

200: Release layer 210: First release layer

220: Second release layer