Double-sided adhesive body and multilayer structure

Abstract

To provide a double-sided adhesive body and a multilayer structure.SOLUTION: A double-sided adhesive body contains a first adhesive layer and a second adhesive layer. The first adhesive layer is a product of a first adhesive composition. The first adhesive composition contains a first copolymer and a first crosslinking agent, and the first copolymer is a product of a first copolymer composition. The second adhesive layer is a product of a second adhesive composition. The second adhesive composition contains a second copolymer and a second crosslinking agent, and the second copolymer is a product of a second copolymer composition. The first copolymer composition contains a (A1) monomer, and the second copolymer composition contains a (B1) monomer. The (A1) monomer and the (B1) monomer each contain a first monomer, a second monomer and a third monomer. A weight percentage of the third monomer in the (A1) monomer is represented by W1, a weight percentage of the third monomer in the (B1) monomer is represented by W2, and the weight percentages satisfy 45 wt.%≥W2-W1≥7 wt.%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a double-sided adhesive and a multilayer structure.

Background Art

[0002] Conventional touch control technologies for touch control displays include adhering and fixing a cover plate of a touch control display and a touch control plate using an optical adhesive, and adhering and fixing a touch control plate and a polarizing plate of a display module using an optical adhesive. Many conventional optical adhesive products emphasize their strong adhesive force so that the two panels to be adhered do not peel off. However, the strong adhesive characteristics also have the drawback of being inconvenient in rework.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The panel rework process of panel manufacturers can be mainly divided into two types. One is to process the panel at a low temperature and then peel off the panel adhered with two optical adhesives. The other is to mechanically cut the optical adhesive and then peel off the two panels. Since a part of the optical adhesive adheres to both of the two panels by both methods, both methods require a lot of labor and the use of solvents to remove the adhesive, which is time-consuming and not environmentally friendly. Moreover, the polarizing plate is extremely vulnerable to damage in the process of removing the residual adhesive.

Means for Solving the Problems

[0005] The present disclosure provides a double-sided adhesive body. According to an embodiment of the present disclosure, the double-sided adhesive body may include a first adhesive layer and a second adhesive layer. The first adhesive layer has a first surface, and the second adhesive layer has a second surface. The first adhesive layer may be a product obtained by cross-linking a first adhesive composition, and the first adhesive composition includes a first copolymer and a first cross-linking agent. The first copolymer may be a product obtained by copolymerizing a first copolymer composition. The first copolymer composition includes a monomer (A1), and the monomer (A1) may include a first monomer, a second monomer, and a third monomer. In the monomer (A1), the weight percentage of the third monomer with respect to the weight of the monomer (A1) is W1. The first monomer is a (meth)acrylate monomer having a hydroxyl group. The second monomer is a (meth)acrylate monomer whose homopolymer has a glass transition temperature of -20°C or lower. The third monomer is a monomer having a terminal vinyl group whose homopolymer has a glass transition temperature of 0°C or higher. The second adhesive layer may be a product obtained by cross-linking a second adhesive composition. The second adhesive composition may include a second copolymer and a second cross-linking agent. The second copolymer may be a product obtained by copolymerizing a second copolymer composition. The second copolymer composition may include a monomer (B1), and the monomer (B1) may include a first monomer, a second monomer, and a third monomer. In the monomer (B1), the weight percentage of the third monomer with respect to the weight of the monomer (B1) is W2. It should be noted that the weight percentage W1 and the weight percentage W2 satisfy the following relationship: 45wt% ≥ W2 - W1 ≥ 7wt%.

[0006] According to an embodiment of the present disclosure, the present disclosure also provides a multilayer structure. The multilayer structure may include a first substrate, a second substrate, and the double-sided adhesive body described above. The first adhesive layer of the double-sided adhesive body has a first surface, and the second adhesive layer of the double-sided adhesive body has a second surface. The first surface is in contact with the first substrate, and the second surface is in contact with the second substrate.

Advantages of the Invention

[0007] The present disclosure provides a double-sided adhesive body, for example, a double-sided adhesive body that can be peeled off by freezing. According to an embodiment of the present disclosure, the double-sided adhesive body according to the present disclosure has a first adhesive layer and a second adhesive layer. By controlling the difference in the content of the hard monomer in the first adhesive layer and the hard monomer in the second adhesive layer, the difference in the adhesion between the first adhesive layer and the second adhesive layer after the double-sided adhesive body is subjected to a low-temperature treatment becomes large. As a result, during the rework process, the double-sided adhesive body can be smoothly peeled off from the base material (the base material in contact with the second adhesive layer of the double-sided adhesive body), and no adhesive material remains.

[0008] According to an embodiment of the present disclosure, the present disclosure also provides a multilayer structure including the double-sided adhesive body, for example, a display panel. According to an embodiment of the present disclosure, the first adhesive layer of the double-sided adhesive body may have a first surface, the second adhesive layer of the double-sided adhesive body has a second surface, the first surface may be used to adhere and fix a touch control panel, and the second surface is used to adhere and fix a polarizing plate of a display module. When the double-sided adhesive body is subjected to a low-temperature treatment, the adhesion between the first surface and the second surface of the double-sided adhesive body decreases, and a large difference occurs between the adhesion of the first surface of the first adhesive layer and the adhesion of the second surface of the second adhesive layer. After the peeling process, the two adhered base materials can be easily peeled off. In addition, the double-sided adhesive body according to the present disclosure only remains on one base material (for example, a touch control panel), and does not remain on two base materials at the same time (for example, no adhesive residue is formed on the polarizing plate). Therefore, the reuse rate of the display panel element is increased, and the efficiency of the rework process is increased.

[0009] Detailed descriptions will be given in the following embodiments.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0011] In the following description, the double-sided adhesive and the multilayer structure will be described in detail. In the following detailed description, for the purpose of explanation, a number of specific details and embodiments are shown so that the present disclosure can be fully understood. The specific components and configurations described in the following detailed description are shown for the purpose of clearly explaining the present disclosure. However, it will be apparent that the exemplary embodiments shown herein are merely used for the purpose of explanation, and the inventive concept can be embodied in various forms without being limited to those exemplary embodiments. As used herein, the term "about" in terms of quantity refers to an increase or decrease by an amount that is normal and reasonable for those skilled in the art.

[0012] Also, the use of terms indicating order such as "first", "second", "third", etc. for modifying components in the present disclosure does not itself imply the priority, precedence, or order of one component according to one claim over another component, or the temporal order in which it is formed. Instead, it is merely a label for distinguishing components according to claims, for distinguishing a component according to one claim having a certain name from another component having the same name (if there is no use of terms indicating order).

[0013] It should be noted that the elements or devices in the drawings of the present disclosure may be presented in any form or configuration known to those skilled in the art. In addition, the expressions "a layer covering another layer", "a layer is disposed on another layer", "a layer is disposed over another layer", and "a layer is disposed above another layer" may represent a layer in direct contact with another layer, and may also represent a layer not in direct contact with another layer, in which case there is one or more intermediate layers disposed between the layer and the other layer. The drawn drawings are only schematic and not limiting. For the purpose of explanation, the sizes, shapes, or thicknesses of some elements in the drawings may be exaggerated and not drawn to scale. The dimensions and relative dimensions do not correspond to the actual positions for implementing the present disclosure. The present disclosure is described with reference to specific embodiments and specific drawings, but the present disclosure is not limited thereto.

[0014] According to an embodiment of the present disclosure, referring to FIG. 1, the double-sided adhesive body 10 may include a first adhesive layer 12 and a second adhesive layer 14. The first adhesive layer has a first surface, and the second adhesive layer has a second surface. The first adhesive layer 12 may be a product obtained by cross-linking reaction of a first adhesive composition, and the first adhesive composition may include a first copolymer and a first cross-linking agent. The second adhesive layer 14 may be a product obtained by cross-linking reaction of a second adhesive composition, and the second adhesive composition may include a second copolymer and a second cross-linking agent.

[0015] According to an embodiment of the present disclosure, the first copolymer may be a product obtained by copolymerization reaction of a first copolymer composition. The first copolymer composition includes a monomer (i.e., component (A1)), and the (A1) monomer may include a first monomer, a second monomer, and a third monomer. According to an embodiment of the present disclosure, based on the weight of the (A1) monomer, the total weight of the first monomer, the second monomer, and the third monomer is 95 wt% to 100 wt%.

[0016] According to an embodiment of the present disclosure, the (A1) monomer consists of a main monomer and a secondary monomer. The main monomer consists of a first monomer, a second monomer, and a third monomer. The secondary monomer consists of monomers that can react with (meth)acrylate. Here, the weight of the main monomer is from 95 wt% to 99.9 wt%, and the weight of the secondary monomer is from 0.1 wt% to 5 wt%.

[0017] According to an embodiment of the present disclosure, the (A1) monomer may consist of a first monomer, a second monomer, and a third monomer.

[0018] According to an embodiment of the present disclosure, the second copolymer may be a product obtained by copolymerizing a second copolymer composition. The second copolymer composition contains a (B1) monomer (i.e., component (B1)). The (B1) monomer may contain a first monomer, a second monomer, and a third monomer. According to an embodiment of the present disclosure, with respect to the weight of the (B1) monomer, the total weight of the first monomer, the second monomer, and the third monomer is from 95 wt% to 100 wt%.

[0019] According to an embodiment of the present disclosure, the (B1) monomer consists of a main monomer and a secondary monomer. The main monomer consists of a first monomer, a second monomer, and a third monomer. The secondary monomer consists of monomers that can react with (meth)acrylate. Here, the weight of the main monomer is from 95 wt% to 99.9 wt%, and the weight of the secondary monomer is from 0.1 wt% to 5 wt%.

[0020] According to an embodiment of the present disclosure, the (B1) monomer may consist of a first monomer, a second monomer, and a third monomer.

[0021] In the (A1) monomer, the weight percentage of the third monomer may be W1 with respect to the weight of the (A1) monomer (i.e., the total weight of the first monomer, the second monomer, and the third monomer in the first copolymer composition).

[0022] (B1) In the monomer, the weight percentage of the third monomer may be W2 with respect to the weight of the (B1) monomer (i.e., the total weight of the first monomer, the second monomer, and the third monomer in the second copolymer composition).

[0023] It should be noted that the weight percentage W1 and the weight percentage W2 satisfy the following relationship: 45 wt% ≥ W2 - W1 ≥ 7 wt% (for example, 40 wt% ≥ W2 - W1 ≥ 7 wt%, 35 wt% ≥ W2 - W1 ≥ 7 wt%, 32 wt% ≥ W2 - W1 ≥ 7 wt%, or 28 wt% ≥ W2 - W1 ≥ 7 wt%). According to an embodiment of the present disclosure, when the value of the difference (W2 - W1) between the weight percentage W1 and the weight percentage W2 is less than 7, after the double-sided adhesive is subjected to a low-temperature treatment, there is no significant difference in the adhesive strength between the first adhesive layer and the second adhesive layer.

[0024] According to an embodiment of the present disclosure, the first copolymer composition does not contain other reactive monomers (i.e., monomers that can be used to form repeating units of the first copolymer) in addition to the first monomer, the second monomer, and the third monomer. According to an embodiment of the present disclosure, the second copolymer composition does not contain other reactive monomers (i.e., monomers that can be used to form repeating units of the second copolymer) in addition to the first monomer, the second monomer, and the third monomer.

[0025] According to an embodiment of the present disclosure, the composition of the (A1) monomer in the first copolymer composition is the same as the composition of the (B1) monomer in the second copolymer composition. In other words, the first monomer in the first copolymer composition may be the same as the first monomer in the second copolymer composition, the second monomer in the first copolymer composition may be the same as the second monomer in the second copolymer composition, and the third monomer in the first copolymer composition may be the same as the third monomer in the second copolymer composition.

[0026] According to an embodiment of the present disclosure, the composition of the (A1) monomer of the first copolymer composition is different from the composition of the (B1) monomer of the second copolymer composition. In other words, the first monomer of the first copolymer composition is different from the first monomer of the second copolymer composition, the second monomer of the first copolymer composition is different from the second monomer of the second copolymer composition, and / or the third monomer of the first copolymer composition is different from the third monomer of the second copolymer composition.

[0027] According to an embodiment of the present disclosure, the first monomer may be a (meth)acrylate monomer having a hydroxyl group. According to some embodiments of the present disclosure, the first monomer may be as follows.

[0028] [Chemical formula]

[0029] In the formula, R 1 may be hydrogen or a methyl group, and R 2 may be hydrogen, or a C 1-10 alkylol group. According to an embodiment of the present disclosure, the C 1-10 alkylol group may be a linear or branched alkylol group. For example, C 1-10The alkylol group may be a methylol group, an ethylol group, a propylol group, a butylol group, a pentylol group, a hexylol group, or an isomer thereof. By way of example, the first monomer may be acrylic acid, methacrylic acid, hydroxyethyl (meth)acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, or a combination of the foregoing.

[0030] According to an embodiment of the present disclosure, the second monomer may be a soft monomer, and the soft monomer refers to a (meth)acrylate monomer whose homopolymer has a glass transition temperature of -20°C or lower (for example, a glass transition temperature of -20°C to -100°C, a glass transition temperature of -20°C to -90°C, a glass transition temperature of -20°C to -80°C, or a glass transition temperature of -20°C to -70°C). In other words, the second monomer may be a (meth)acrylate monomer, and the glass transition temperature of the homopolymer of the (meth)acrylate monomer is -20°C or lower. The glass transition temperature is measured by differential scanning calorimetry (DSC) (heating rate: 10°C / min), or the literature values such as those in POLYMER HANDBOOK (Wiley-Interscience) are referred to. For example, the second monomer may be n-butyl acrylate, sec-butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, ethoxyethyl acrylate, isononyl acrylate, lauryl methacrylate, or a combination thereof as described above.

[0031] According to an embodiment of the present disclosure, the third monomer may be a hard monomer, and the hard monomer refers to a monomer having a terminal vinyl group with a glass transition temperature of the homopolymer of 0 °C or higher (for example, a glass transition temperature of 0 °C to 200 °C, a glass transition temperature of 0 °C to 180 °C, a glass transition temperature of 0 °C to 150 °C, or a glass transition temperature of 0 °C to 130 °C). In other words, the third monomer may be a monomer having a terminal vinyl group, and the glass transition temperature of the homopolymer of the monomer having the terminal vinyl group is 0 °C or higher. For example, the third monomer may be tert-butyl acrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, methyl acrylate, methyl methacrylate, acrylonitrile, acrylamide, acryloyl morpholine, N-vinyl-2-pyrrolidone, or a combination of the above.

[0032] According to embodiments of the present disclosure, in the (A1) monomer, the weight percentage of the first monomer may be from 1 wt% to 10 wt% (for example, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, or 9 wt%) based on the weight of the (A1) monomer. When the weight percentage of the first monomer in the (A1) monomer is from 1 wt% to 10 wt%, the first copolymer will have an appropriate number of hydroxyl groups, be able to react better with the crosslinking agent, and the resulting crosslinked product will have weather resistance. According to embodiments of the present disclosure, in the (B1) monomer, the weight percentage of the first monomer may be from 1 wt% to 10 wt% (for example, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, or 9 wt%) based on the weight of the (B1) monomer. When the weight percentage of the first monomer in the (B1) monomer is from 1 wt% to 10 wt%, the second copolymer will have an appropriate number of hydroxyl groups, be able to react better with the crosslinking agent, and the resulting crosslinked product will have weather resistance.

[0033] According to embodiments of the present disclosure, in the (A1) monomer, the weight percentage of the first monomer may be from 1 wt% to 10 wt% based on the total weight of the first monomer, the second monomer, and the third monomer. According to embodiments of the present disclosure, in the (B1) monomer, the weight percentage of the first monomer may be from 1 wt% to 10 wt% based on the total weight of the first monomer, the second monomer, and the third monomer.

[0034] According to an embodiment of the present disclosure, in the (A1) monomer, the weight percentage of the second monomer may be from 50 wt% to 95 wt% (for example, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, or 94 wt%) based on the weight of the (A1) monomer. According to an embodiment of the present disclosure, in the (B1) monomer, the weight percentage of the second monomer may be from 50 wt% to 95 wt% (for example, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, or 94 wt%) based on the weight of the (B1) monomer.

[0035] According to an embodiment of the present disclosure, in the (A1) monomer, the weight percentage of the second monomer may be from 50 wt% to 95 wt% based on the total weight of the first monomer, the second monomer, and the third monomer. According to an embodiment of the present disclosure, in the (B1) monomer, the weight percentage of the second monomer may be from 50 wt% to 95 wt% based on the total weight of the first monomer, the second monomer, and the third monomer.

[0036] According to embodiments of the present disclosure, in the (A1) monomer, the weight percentage of the third monomer with respect to the weight of the (A1) monomer may be from 4 wt% to 49 wt% (for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, or 48 wt%). According to embodiments of the present disclosure, in the (B1) monomer, the weight percentage of the third monomer with respect to the weight of the (B1) monomer may be from 4 wt% to 49 wt% (for example, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, or 48 wt%).

[0037] According to embodiments of the present disclosure, in the (A1) monomer, the weight percentage of the third monomer with respect to the total weight of the first monomer, the second monomer, and the third monomer may be from 4 wt% to 49 wt%. According to embodiments of the present disclosure, in the (B1) monomer, the weight percentage of the third monomer with respect to the total weight of the first monomer, the second monomer, and the third monomer may be from 4 wt% to 49 wt%.

[0038] According to an embodiment of the present disclosure, in the first copolymer composition or the second copolymer composition, when the content of the soft monomer (i.e., a (meth)acrylate monomer having a glass transition temperature of the homopolymer of -20°C or lower) is relatively high, the resulting copolymer will have a relatively low glass transition temperature. Also, in the first copolymer composition or the second copolymer composition, when the content of the hard monomer (i.e., a monomer having a terminal vinyl group with a glass transition temperature of the homopolymer of 0°C or higher) is relatively high, the resulting copolymer will have a relatively high glass transition temperature. Therefore, by adjusting the content of the hard monomer (i.e., the third monomer) in the first copolymer composition and the second copolymer composition, the difference in the glass transition temperature of the first adhesive layer and the second adhesive layer can be increased (i.e., the glass transition temperature (Tg 2 ) of the copolymer used for the second adhesive layer is made larger than the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer). By doing so, when the double-sided adhesive body according to the present disclosure is subjected to a low-temperature treatment, the difference in the adhesive strength between the first adhesive layer and the second adhesive layer can be made even larger, so that the double-sided adhesive body according to the present disclosure can be peeled off from the second adhesive layer side, and no residue of the adhesive material occurs.

[0039] According to an embodiment of the present disclosure, using the Fox equation, the estimated glass transition temperature of the copolymer used for the adhesive layer (for example, the first adhesive layer or the second adhesive layer) can be calculated. The calculation formula of the Fox equation is as follows. 1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 + … Wn / Tgn In the formula, Tg is the glass transition temperature (K) of the adhesive layer, W1 is the weight fraction of monomer 1, Tg1 is the glass transition temperature (K) of the homopolymer of monomer 1, W2 is the weight fraction of monomer 2, Tg2 is the glass transition temperature (K) of the homopolymer of monomer 2, Wn is the weight fraction of monomer N, and Tgn is the glass transition temperature (K) of the homopolymer of monomer N. Monomers 1 to N refer to various monomers used to produce a copolymer (for example, the first copolymer or the second copolymer), and the copolymer is used to produce the adhesive layer.

[0040] According to an embodiment of the present disclosure, when performing a low-temperature treatment on the double-sided adhesive body in the rework process, the temperature (T) of the low-temperature treatment is set to be lower than the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer and the glass transition temperature (Tg 2 ) of the copolymer used for the second adhesive layer. In other words, the temperature (T) of the low-temperature treatment, the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer, and the glass transition temperature (Tg 2 ) of the copolymer used for the second adhesive layer satisfy the following relationship: Tg 2 >Tg 1 >T. By doing so, in the double-sided adhesive body according to the present disclosure, a large difference may occur in the adhesive strength between the first adhesive layer and the second adhesive layer after the low-temperature treatment. According to an embodiment of the present disclosure, the value of the difference between the glass transition temperature Tg 2 of the copolymer used for the second adhesive layer and the glass transition temperature Tg 1 of the copolymer used for the first adhesive layer (that is, Tg 2 -Tg 1 ) may be 10 °C or higher (that is, Tg 2 -Tg 1 ≧10 °C).

[0041] According to an embodiment of the present disclosure, the time of the cryogenic treatment according to the present disclosure may be from about 1 minute to 1 hour, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, or 55 minutes. According to an embodiment of the present disclosure, the temperature of the cryogenic treatment may be from about -10°C to -130°C, for example, -15°C, -20°C, -25°C, -30°C, -40°C, -50°C, -60°C, -70°C, -80°C, -90°C, -100°C, -110°C, or -120°C. According to an embodiment of the present disclosure, the lower the temperature (T) of the cryogenic treatment, the shorter the time of the cryogenic treatment.

[0042] According to an embodiment of the present disclosure, when performing cryogenic treatment on the double-sided adhesive body in the rework process, the temperature (T) of the cryogenic treatment is the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer and the glass transition temperature (Tg 2 ) of the copolymer used for the second adhesive layer. In other words, the temperature (T) of the cryogenic treatment, the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer, and the glass transition temperature (Tg 2 ) of the copolymer used for the second adhesive layer have the following relationship: Tg 2 > T> Tg 1 can be satisfied. By doing so, after performing cryogenic treatment on the double-sided adhesive body according to the present disclosure, the difference in adhesive strength between the first adhesive layer and the second adhesive layer can be made larger, and the double-sided adhesive body can be surely peeled off smoothly from the base material (the base material in contact with the second adhesive layer of the double-sided adhesive body) during the rework process, and no residue of the adhesive material will occur. According to an embodiment of the present disclosure, when the temperature (T) of the cryogenic treatment is between the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer and the glass transition temperature (Tg 2 ) of the copolymer used for the second adhesive layer, the energy loss during the cryogenic treatment can be reduced (that is, it is not necessary to lower the temperature below the glass transition temperature (Tg 1 ) of the copolymer used for the first adhesive layer).

[0043] According to an embodiment of the present disclosure, the first copolymer composition may further include an (A2) initiator, and the weight ratio of the (A1) monomer to the (A2) initiator may be from 10,000:1 to 100:3, such as 8,000:1, 6,000:1, 5,000:1, 3,000:1, 2,000:1, 1,750:1, 1,500:1, 1,250:1, 1,000:1, 750:1, 500:1, 200:1, 100:1, 100:2, or 100:2.5.

[0044] According to an embodiment of the present disclosure, the second copolymer composition may further include a (B2) initiator, and the weight ratio of the (B1) monomer to the (B2) initiator may be from 10,000:1 to 100:3, such as 8,000:1, 6,000:1, 5,000:1, 3,000:1, 2,000:1, 1,750:1, 1,500:1, 1,250:1, 1,000:1, 750:1, 500:1, 200:1, 100:1, 100:2, or 100:2.5.

[0045] According to an embodiment of the present disclosure, the (A2) initiator and the (B2) initiator may be thermal initiators. According to an embodiment of the present disclosure, there are no particular restrictions on the selection of the (A2) initiator and the (B2) initiator, and they may be azo compounds, cyanovaleric - acid - based compounds, peroxides, benzoin - based compounds, acetophenone - based compounds, thioxanthone - based compounds, ketal compounds, benzophenone - based compounds, α - aminoacetophenone compounds, acylphosphine oxide compounds, biimidazole - based compounds, triazine - based compounds, or combinations thereof.

[0046] According to embodiments of the present disclosure, the azo compound may be 2,2’-azobis(2,4-dimethyl valeronitrile), dimethyl 2,2’-azobis(2-methylpropionate), 2,2-azobisisobutyronitrile (hereinafter referred to as AIBN), 2,2-azobis(2-methylisobutyronitrile), 1,1’-azobis(cyclohexane-1-carbonitrile), 2,2’-azobis[N-(2-propenyl)-2-methylpropionamide], 1-[(cyano-1-methylethyl)azo]formamide, 2,2’-azobis(N-butyl-2-methylpropionamide), or 2,2’-azobis(N-cyclohexyl-2-methylpropionamide). The peroxide may be benzoyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane, 2,5-bis(tert-butylperoxy)-2,5-dimethylcyclohexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-cyclohexene, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-cyclohexyne), bis(1-(tert-butylpeorxy)-1-methy-ethyl)benzene, tert-butyl hydroperoxide, tert-butyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, cyclohexanone peroxide, dicumyl peroxide, or lauroyl peroxide. The benzoin compound may be benzoin, benzoin methyl ether, or benzyl dimethyl ketal. The acetophenone compound may be p-dimethylamino-acetophenone, α,α’-dimethoxyazoxy-acetophenone, 2,2’-dimethyl-2-phenyl-acetophenone, p-methoxy-acetophenone, 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone. The benzophenone compound may be benzophenone, 4,4-bis(dimethylamino)benzophenone, 4,4-bis(dimethylamino)benzophenone), 4,4-bis(diethylamino)benzophenone, 2,4,6-trimethylaminobenzophenone, methyl-o-benzoyl benzoate, 3,3-dimethyl-4-methoxybenzophenone, and 3,3,4,4-tetra(t-butylperoxycarbonyl)benzophenone may be used. The thioxanthone-based compounds may be thioxanthone, 2,4-diethyl-thioxanthanone, and thioxanthone-4-sulfone. The biimidazole-based compounds may be 2,2’-bis(o-chlorophenyl)-4,4’,5,5’-tetraphenyl-biimidazole, 2,2’-bis(o-fluorophenyl)-4,4’,5,5’-tetraphenyl-biimidazole, 2,2’-bis(o-methylphenyl)-4,4’,5,5’-tetraphenyl-biimidazole, 2,2’-bis(o-methoxyphenyl)-4,4’,5,5’-tetraphenyl-biimidazole, 2,2’-bis(o-ethylphenyl)-4,4’,5,5’-tetraphenyl-biimidazole, 2,2’-bis(o-ethylphenyl)-4,4’,5,5'-tetraphenyl-biimidazole], 2,2'-bis(p-methoxyphenyl)-4,4',5,5'-tetraphenyl-biimidazole, 2,2'-bis(2,2',4,4'-tetramethoxyphenyl)-4,4',5,5'-tetraphenyl-biimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-biimidazole may be used. The phosphine oxide compound may be 2,4,6-trimethylbenzoyl diphenylphosphine oxide and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. The triazine compound may be 3-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}propionic acid, 1,1,1,3,3,3-hexafluoroisopropyl-3-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}propionate, 1,1,1,3,3,3-hexafluoroisopropyl-3-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}propionate), ethyl-2-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}acetate, 2-epoxyethyl-2-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}acetate, cyclohexyl-2-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}acetate, benzyl-2-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}acetate, 3-{chloro-4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}propionic acid, 3-{4-[2,4-bis(trichloromethyl)-s-triazine-6-yl]phenylthio}propionamide, 2,4-bis(trichloromethyl)-6-p-methoxystyryl-s-triazine, 2,4-bis(trichloromethyl)-6-(1-p-dimethylaminophenyl)-1,3-butadienyl-s-triazine, 2,It may be 4-bis(trichloromethyl)-6-(1-p-dimethylaminophenyl)-1,3,-butadienyl-s-triazine) or 2-trichloromethyl-4-amino-6-p-methoxystyryl-s-triazine).

[0047] According to an embodiment of the present disclosure, the first copolymer composition may further include (A3) a solvent. The amount of the solvent used can be adjusted as needed to uniformly disperse the (A1) monomer and (A2) initiator in the solvent. For example, the solid content of the first copolymer composition may be from 20 wt% to 70 wt% (such as about 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or 65 wt%). Here, the solid content refers to the weight percentage of all components of the first copolymer composition excluding the solvent with respect to the total weight of the first copolymer composition.

[0048] According to an embodiment of the present disclosure, the second copolymer composition may further include (B3) a solvent. The amount of the solvent used can be adjusted as needed to evenly disperse the (B1) monomer and (B2) initiator in the solvent. For example, the solid content of the second copolymer composition may be from 20 wt% to 70 wt% (such as about 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or 65 wt%). Here, the solid content refers to the weight percentage of all components of the second copolymer composition excluding the solvent with respect to the total weight of the second copolymer composition.

[0049] According to embodiments of the present disclosure, the (A3) solvent and the (B3) solvent may each independently be an aromatic hydrocarbon solvent, an alcohol solvent, an ether solvent, a ketone solvent, an ester solvent, a nitrogen-containing solvent, or a combination of the above. According to embodiments of the present disclosure, the (A3) solvent and the (B3) solvent may each independently be benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, triethylbenzene, cyclohexane, cyclohexene, decahydronaphthalene, dipentene, pentane, hexane, heptane, octane, nonane, decane, ethyl cyclohexane, methyl cyclohexane, cyclohexane, cyclohexene, p-menthane, dipropyl ether, dibutyl ether, anisole, ethyl acetate, butyl acetate, pentyl acetate, methyl isobutyl ketone, cyclohexylbenzene, cyclohexanone, cyclopentanone (CPN), triglyme, 1,3-dimethyl-2-imidazolidinone,DMI), N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone (MEK), N,N-dimethylacetamide (DMAc), γ-butyrolactone (GBL), N,N-dimethylformamide (DMF), propylene glycol methyl ether acetate (PGMEA), dimethyl sulfoxide (DMSO), or a combination thereof as described above may be used.

[0050] According to an embodiment of the present disclosure, the first copolymer composition may consist of the (A1) monomer, (A2) initiator, and (A3) solvent. According to an embodiment of the present disclosure, the second copolymer composition may consist of the (B1) monomer, (B2) initiator, and (B3) solvent.

[0051] According to an embodiment of the present disclosure, there is no particular limitation on the molecular weight of the first copolymer according to the present disclosure, and those having ordinary knowledge in the art can adjust it according to actual needs so that the first copolymer undergoes a crosslinking reaction with the first crosslinking agent to form the first adhesive layer. According to an embodiment of the present disclosure, the weight average molecular weight (Mw) of the first copolymer may be from about 50,000 (g / mol) to 500,000 (g / mol), for example, about 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), or 400,000 (g / mol).

[0052] According to an embodiment of the present disclosure, there is no particular limitation on the molecular weight of the second copolymer according to the present disclosure, and those having ordinary knowledge in the art can adjust it according to actual needs so that the second copolymer undergoes a crosslinking reaction with the second crosslinking agent to form the second adhesive layer. According to an embodiment of the present disclosure, the weight average molecular weight (Mw) of the second copolymer may be from about 50,000 (g / mol) to 500,000 (g / mol), for example, about 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), or 400,000 (g / mol). The weight average molecular weight (Mw) of the copolymer according to the present disclosure can be measured by gel permeation chromatography (GPC) (a calibration curve is prepared using polystyrene as a standard).

[0053] According to an embodiment of the present disclosure, the method for preparing the copolymer according to the present disclosure may include the following steps. First, a copolymer composition (for example, a first copolymer composition or a second copolymer composition) is prepared. Next, a heating step is performed on the copolymer composition. The temperature of the heating step can be from 60°C to 130°C, and the process time can be from 5 hours to 24 hours.

[0054] According to an embodiment of the present disclosure, in the first adhesive composition, the weight ratio of the first crosslinking agent to the first copolymer is from about 1:5,000 to 5:100, for example, 2:5,000, 3:5,000, 4:5,000, 1:1,000, 2:1,000, 3:1,000, 4:1,000, 5:1,000, 8:1,000, 1:100, 2:100, 3:100, or 4:100. According to an embodiment of the present disclosure, in the second adhesive composition, the weight ratio of the second crosslinking agent to the second copolymer is from about 1:5,000 to 5:100, for example, 3:1,000, 4:1,000, 5:1,000, 8:1,000, 1:100, 2:100, 3:100, or 4:100.

[0055] According to an embodiment of the present disclosure, the first crosslinking agent and the second crosslinking agent may each independently be a compound having at least two crosslinkable functional groups (for example, a compound having two crosslinkable functional groups, a compound having three crosslinkable functional groups, a compound having four crosslinkable functional groups, or a compound having five crosslinkable functional groups), and the crosslinkable functional group may be an isocyanate group, a carboxyl group, an aziridine group, an anhydride group, or a melamine group. By way of example, the first crosslinking agent and the second crosslinking agent may each independently be 2,4-toluene diisocyanate, 2,5-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate (HMDI), pentamethylene diisocyanate, isophorone diisocyanate, dicyclohexyl methylene diisocyanate (4,4'-Methylene dicyclohexyl diisocyanate), 4,4’-methylenediphenyl diisocyanate, or a combination of the above.

[0056] According to an embodiment of the present disclosure, the first adhesive composition may further include a first solvent. The amount of the first solvent used can be adjusted as needed so that the first copolymer and the first crosslinking agent are uniformly dispersed in the solvent. For example, the solid content of the first adhesive composition may be from 20 wt% to 70 wt% (e.g., about 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or 65 wt%). Here, the solid content refers to the weight percentage of all components of the first adhesive composition excluding the first solvent with respect to the total weight of the first adhesive composition.

[0057] According to an embodiment of the present disclosure, the second adhesive composition may further include a second solvent. The amount of the second solvent used can be adjusted as needed so that the second copolymer and the second crosslinking agent are uniformly dispersed in the solvent. For example, the solid content of the second adhesive composition may be from 20 wt% to 70 wt% (e.g., about 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or 65 wt%). Here, the solid content refers to the weight percentage of all components of the second adhesive composition excluding the second solvent with respect to the total weight of the second adhesive composition.

[0058] According to an embodiment of the present disclosure, the first solvent and the second solvent may each independently be an aromatic hydrocarbon solvent, an alcohol solvent, an ether solvent, a ketone solvent, an ester solvent, a nitrogen-containing solvent, or a combination of the above. According to an embodiment of the present disclosure, the first solvent and the second solvent may each independently be benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, triethylbenzene, cyclohexane, cyclohexene, decahydronaphthalene, dipentene, pentane, hexane, heptane, octane, nonane, decane, ethyl cyclohexane, methyl cyclohexane, cyclohexane, cyclohexene, p-menthane, dipropyl ether, dibutyl ether, anisole, ethyl acetate, butyl acetate, pentyl acetate, methyl isobutyl ketone, cyclohexylbenzene, cyclohexanone, cyclopentanone (CPN), triglyme, 1,3-dimethyl-2-imidazolidinone,DMI), N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone (MEK), N,N-dimethylacetamide (DMAc), γ-butyrolactone (GBL), N,N-dimethylformamide (DMF), propylene glycol methyl ether acetate (PGMEA), dimethyl sulfoxide (DMSO), or a combination thereof may be used.

[0059] According to an embodiment of the present disclosure, the first adhesive composition may be composed of the first copolymer, the first crosslinking agent, and the first solvent. According to an embodiment of the present disclosure, the second adhesive composition may be composed of the second copolymer, the second crosslinking agent, and the second solvent.

[0060] According to an embodiment of the present disclosure, the first adhesive composition may further include a first catalyst such that the crosslinking reaction of the first adhesive composition is accelerated. According to an embodiment of the present disclosure, the weight ratio of the first catalyst to the first copolymer may be from about 1:10,000 to 1:100, such as 1:5,000, 2:5,000, 3:5,000, 4:5,000, 1:1,000, 2:1,000, 3:1,000, 4:1,000, 5:1,000, 6:1,000, 7:1,000, 8:1,000, or 9:1,000.

[0061] According to an embodiment of the present disclosure, the second adhesive composition may further include a second catalyst so that the crosslinking reaction of the second adhesive composition is accelerated. According to an embodiment of the present disclosure, the weight ratio of the second catalyst to the second copolymer may be from about 1:10,000 to 1:100, such as 1:5,000, 2:5,000, 3:5,000, 4:5,000, 1:1,000, 2:1,000, 3:1,000, 4:1,000, 5:1,000, 6:1,000, 7:1,000, 8:1,000, or 9:1,000.

[0062] According to an embodiment of the present disclosure, the first catalyst and the second catalyst are each independently bismuth nitrate, bismuth neodecanoate, lead 2-ethylhexoate, lead benzoate, neodecanoic acid lithium salt, ferric chloride, antimony trichloride, antimony glycolate, stannous salts of carboxylic acids, zinc salts of carboxylic acids, dialkyl tin salts of carboxylic acids, glycine salts, tertiary amine trimerization catalysts, quaternary ammonium carboxylates, alkali metal carboxylic acid salts, potassium acetate, potassium octoate, potassium 2-ethylhexanoate, N-(2-hydroxy-5-nonylphenyl)methyl-N-methylglycinate, tin (II) 2-ethylhexanoate, dibutyltin dilaurate, or a combination of the above.

[0063] According to an embodiment of the present disclosure, the first adhesive composition may be composed of the first copolymer, the first crosslinking agent, the first solvent, and the first catalyst. According to an embodiment of the present disclosure, the second adhesive composition may be composed of the second copolymer, the second crosslinking agent, the second solvent, and the second catalyst.

[0064] According to an embodiment of the present disclosure, there is no particular limitation on the molecular weight of the crosslinking reaction product (i.e., the first adhesive layer) obtained from the first adhesive composition according to the present disclosure, and those having ordinary knowledge in the art can adjust it as needed. According to an embodiment of the present disclosure, the weight average molecular weight (Mw) of the product obtained from the first adhesive composition may be from about 50,000 (g / mol) to 2,000,000 (g / mol), for example, about 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), or 1,500,000 (g / mol).

[0065] According to an embodiment of the present disclosure, there is no particular limitation on the molecular weight of the crosslinking reaction product (i.e., the second adhesive layer) obtained from the second adhesive composition according to the present disclosure, and those having ordinary knowledge in the art can adjust it as needed. According to an embodiment of the present disclosure, the weight average molecular weight (Mw) of the product obtained from the second adhesive composition may be from about 50,000 (g / mol) to 2,000,000 (g / mol), for example, about 80,000 (g / mol), 100,000 (g / mol), 200,000 (g / mol), 300,000 (g / mol), 400,000 (g / mol), 500,000 (g / mol), 800,000 (g / mol), 1,000,000 (g / mol), or 1,500,000 (g / mol). The weight average molecular weight (Mw) of the crosslinking reaction product according to the present disclosure can be measured by gel permeation chromatography (GPC) (a calibration curve is prepared using polystyrene as a standard).

[0066] According to an embodiment of the present disclosure, a method for producing an adhesive layer (for example, a first adhesive layer or a second adhesive layer) according to the present disclosure may include the following steps. First, an adhesive composition (for example, a first adhesive composition or a second adhesive composition) is prepared. Next, a coating layer is formed on a substrate with the adhesive composition by a coating process. Then, a heating process is performed on the coating layer to obtain the adhesive layer. The temperature of the heating process can be from 60°C to 120°C, and the process time can be from 1 minute to 60 minutes.

[0067] According to an embodiment of the present disclosure, a method for producing a double-sided adhesive body according to the present disclosure may include the following steps. First, a first coating layer is formed on a first release film with a first adhesive composition by a coating process. Next, a heating process is performed on the coating layer to obtain a first adhesive layer disposed on the first release film. Then, a second coating layer is formed on a second release film with a second adhesive composition by a coating process. Next, a heating process is performed on the coating layer to obtain a second adhesive layer disposed on the second release film. Then, the first adhesive layer is disposed on the second adhesive layer, and a laminating process is performed to form a laminate (the structure is: first release film / first adhesive layer / second adhesive layer / second release film).

[0068] There is no particular limitation on the thickness of the double-sided adhesive body according to the present disclosure, and it can be selected according to actual needs. According to an embodiment of the present disclosure, the average thickness of the double-sided adhesive body may be about 10 μm to 500 μm, for example, 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, or 400 μm. Also, according to an embodiment of the present disclosure, the ratio of the average thickness of the first adhesive layer to the second adhesive layer may be about 5:1 to 1:5, for example, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, or 1:4.

[0069] According to an embodiment of the present disclosure, the present disclosure also provides a multilayer structure 100 as shown in FIG. 2. The multilayer structure 100 includes the double-sided adhesive body 10 according to the present disclosure, a first base material 20, and a second base material 30, and the double-sided adhesive body 10 is disposed between the first base material 20 and the second base material 30. The double-sided adhesive body 10 has a first adhesive layer 12 and a second adhesive layer 14. The first base material 20 is disposed on the first surface 11 of the first adhesive layer 12, and the first base material 20 and the first adhesive layer 12 are in direct contact. The double-sided adhesive body 10 is directly disposed on the second base material 30, and the second surface 13 of the second adhesive layer 14 and the second base material 30 are in direct contact.

[0070] According to an embodiment of the present disclosure, the double-sided adhesive body 10 is used to fix the first base material 20 to the second base material 30 to obtain the multilayer structure 100. Further, after performing a low-temperature treatment on the multilayer structure 100, the first base material 20 can be peeled off from the second base material 30, and no adhesive material remains on the second base material 30. Specifically, after performing a low-temperature treatment on the double-sided adhesive body 10 according to the present disclosure, the adhesive forces of the first adhesive layer 12 and the second adhesive layer 14 of the double-sided adhesive body 10 decrease, and a large difference occurs between the adhesive force of the first surface 11 of the first adhesive layer 12 and the adhesive force of the second surface 13 of the second adhesive layer 14. Therefore, after performing the peeling step, not only can the first base material 20 be easily peeled off from the second base material 30, but the double-sided adhesive body 10 only remains on the first base material 20 and does not remain on the second base material 30. Therefore, the reuse rate of the display panel element is increased, and the efficiency of the rework process is increased.

[0071] According to an embodiment of the present disclosure, after performing a low-temperature treatment on the multilayer structure 10, the adhesive strength (P1) between the first adhesive layer 12 and the first base material 20 is greater than the adhesive strength (P2) between the second adhesive layer 14 and the second base material 30. According to an embodiment of the present disclosure, P1 and P2 satisfy the following condition: P1 - P2 ≥ 200 gf / 25 mm (for example, 300 gf / 25 mm, 400 gf / 25 mm, 500 gf / 25 mm, 600 gf / 25 mm, 700 gf / 25 mm, 800 gf / 25 mm, 900 gf / 25 mm, 1,000 gf / 25 mm, or 1,500 gf / 25 mm). Here, the method for measuring the adhesive strength followed the method defined in ASTM D3330. The measurement conditions for the adhesive strength are as follows. Using a tensile tester (QC-506B1, Cometech), the angle at which the polyethylene terephthalate (PET) base material is peeled off is 180 o The peeling speed is set to 300 mm / min.

[0072] According to an embodiment of the present disclosure, the first base material 20 and the second base material 30 can be two base materials to be joined. According to an embodiment of the present disclosure, there is no particular limitation on the base material, which may be a metal sheet material, a silicon base material, glass, or a polymer film, and any necessary film layer may already be formed on the base material. For example, the first base material 20 and the second base material 30 may each independently be glass, a transparent base material, a release film, an optical protection film, a brightness enhancement film, a retardation film, a polarizing plate, a touch control panel, an antireflection film, a light guide plate, or a diffuser film.

[0073] According to some embodiments of the present disclosure, the multilayer structure 100 may be a display panel, the first base material 20 may be a touch control panel, and the second base material 30 may be a polarizing plate. The touch control panel may include a transparent glass or a transparent base material, and a transparent conductive electrode is formed on at least one surface of the transparent glass or the transparent base material.

[0074] According to an embodiment of the present disclosure, a method for manufacturing a multilayer structure according to the present disclosure may include the following steps. First, prepare a laminate having a double-sided adhesive according to the present disclosure (the structure is a first release film / first adhesive layer / second adhesive layer / second release film). Next, remove the first release film to expose the first surface of the first adhesive layer, and dispose a first substrate on the first surface of the first adhesive layer to perform a laminating process. Next, remove the second release film to expose the second surface of the second adhesive layer, dispose the second adhesive layer on a second substrate, and perform a laminating process to obtain a multilayer structure according to the present disclosure.

[0075] Hereinafter, exemplary embodiments will be described in detail so that those having ordinary knowledge in the art can easily understand. The inventive concept can be embodied in various forms without being limited to the exemplary embodiments shown herein.

Example

[0076] Preparation of Copolymer

[0077] Production Example 1 265.09 g of toluene was placed in a reaction flask, and nitrogen was introduced. Next, after heating the reaction flask to 85°C, a solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was 85°C. The solution contained 123.10 g of toluene, 18.96 g of hydroxyethyl acrylate (Tg = 258 K), 28.23 g of acryloyl morpholine (Tg = 418 K), 17.06 g of acrylamide (Tg = 438 K), 63.20 g of n-butyl methacrylate (Tg = 293 K), 387.13 g of n-butyl acrylate (Tg = 219 K), and 1.29 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (1) containing solution was obtained (solid content 57.1 wt%).

[0078] Production Example 2 262.36 g of toluene was placed in a reaction flask, and nitrogen was introduced. Next, after raising the temperature of the reaction flask to 85°C, the solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was 85°C. The solution contained 121.84 g of toluene, 18.96 g of hydroxyethyl acrylate, 45.17 g of acryloyl morpholine, 27.29 g of acrylamide, 86.18 g of n-butyl methacrylate, 331.67 g of n-butyl acrylate, and 1.27 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (2)-containing solution was obtained (solid content 57.1 wt%).

[0079] Production Example 3 236.54 g of toluene was placed in a reaction flask, and nitrogen was introduced. Next, after raising the temperature of the reaction flask to 85°C, the solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was 85°C. The solution contained 109.85 g of toluene, 21.25 g of hydroxypropyl acrylate (Tg = 266K), 79.61 g of acrylamide, 28.73 g of n-butyl methacrylate, 329.58 g of n-butyl acrylate, and 2.3 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (3)-containing solution was obtained (solid content 57.1 wt%).

[0080] Production Example 4 234.90 g of toluene was placed in a reaction flask, and nitrogen was introduced. Subsequently, after the reaction flask was heated to 85°C, the solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was set at 85°C. The said solution contained 109.09 g of toluene, 21.25 g of hydroxypropyl acrylate, 90.13 g of acrylamide, 91.93 g of n-butyl methacrylate, 252.68 g of n-butyl acrylate, and 2.28 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (4)-containing solution was obtained (solid content 57.1 wt%).

[0081] Production Example 5 259.62 g of toluene was placed in a reaction flask, and nitrogen was introduced. Subsequently, after the reaction flask was heated to 85°C, the solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was set at 85°C. The said solution contained 122.12 g of toluene, 23.54 g of hydroxybutyl acrylate (Tg = 208K), 17.78 g of N-vinyl-2-pyrrolidone (Tg = 448K), 12.73 g of acrylonitrile (Tg = 398K), 449.90 g of n-butyl acrylate, and 5.04 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (5)-containing solution was obtained (solid content 57.1 wt%).

[0082] Production Example 6 266.24 g of toluene was placed in a reaction flask, and nitrogen was introduced. Subsequently, after heating the reaction flask to 85°C, the solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was set at 85°C. The solution contained 125.23 g of toluene, 23.54 g of hydroxybutyl acrylate, 17.78 g of N-vinyl-2-pyrrolidone, 12.73 g of acrylonitrile, 143.64 g of n-butyl methacrylate, 319.12 g of n-butyl acrylate, and 5.17 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (6)-containing solution was obtained (solid content 57.1 wt%).

[0083] Production Example 7 233.47 g of toluene was placed in a reaction flask, and nitrogen was introduced. Subsequently, after heating the reaction flask to 85°C, the solution was added to the reaction flask to allow the reaction to proceed. The reaction temperature was set at 85°C. The solution contained 108.42 g of toluene, 21.25 g of hydroxypropyl acrylate, 90.98 g of acrylamide, 68.95 g of n-butyl methacrylate, 272.03 g of n-butyl acrylate, and 2.27 g of azobisisobutyronitrile. After reacting for 16 hours, a copolymer (7)-containing solution was obtained (solid content 57.1 wt%).

[0084] The contents of the first monomer, the second monomer, and the third monomer used to prepare copolymers (1) to (7), and the estimated glass transition temperatures of copolymers (1) to (7) are as shown in Table 1. The estimated glass transition temperatures were calculated using the Fox equation.

[0085]

Table 1

[0086] Preparation of Adhesive Composition and Adhesive Layer

[0087] Production Example 8 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Next, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Next, 175.25 g of the copolymer (1) - containing solution and 103.0 g of toluene were placed in a reaction flask. After thoroughly stirring and mixing, 1.33 g of the above - mentioned HMDI solution and 0.25 g of the above - mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (1) was obtained (solid content 35.8 wt%).

[0088] Using a scraper with a gap of 420 μm and a width of 150 mm and a flow coater (model number ZAA2300, sold by ZEHNTNER), the adhesive composition (1) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H338A, sold by Nan Ya Plastics Industry Co., Ltd.). Next, the release film was placed in an oven and dried at 100 °C for 5 minutes and aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (1) disposed on a lightly - peelable PET substrate was obtained.

[0089] Production Example 9 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Next, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Next, 175.25 g of the copolymer (2) - containing solution and 103.0 g of toluene were placed in a reaction flask. After thoroughly stirring and mixing, 1.58 g of the above - mentioned HMDI solution and 0.25 g of the above - mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (2) was obtained (solid content 35.8 wt%).

[0090] Using a scraper and a flow coater with a gap of 420 μm and a width of 150 mm (model number ZAA2300, purchased from ZEHNTNER), the adhesive composition (2) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H838A, sold by Nan Ya Plastics Industry Co., Ltd.). Next, the release film was placed in an oven and dried at 100 °C for 5 minutes, and then aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (2) disposed on a double - release PET substrate was obtained.

[0091] Production Example 10 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Next, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Next, 175.06 g of the copolymer (3) - containing solution and 56.0 g of toluene were placed in a reaction flask. After thoroughly stirring and mixing, 1.48 g of the above - mentioned HMDI solution and 0.25 g of the above - mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (3) was obtained (solid content 43.0 wt%).

[0092] Using a scraper and a flow coater with a gap of 420 μm and a width of 150 mm (model number ZAA2300, purchased from ZEHNTNER), the adhesive composition (3) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H338A, sold by Nan Ya Plastics Industry Co., Ltd.). Subsequently, the release film was placed in an oven and dried at 100 °C for 5 minutes and aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (3) disposed on a lightly peelable PET substrate was obtained.

[0093] Production Example 11 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Subsequently, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Next, 175.06 g of a solution containing the copolymer (4) and 55.5 g of toluene were placed in a reaction flask. After thoroughly stirring and mixing, 2.05 g of the above-mentioned HMDI solution and 0.25 g of the above-mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (4) was obtained (solid content 43.0 wt%).

[0094] Using a scraper and a flow coater with a gap of 420 μm and a width of 150 mm (model number ZAA2300, purchased from ZEHNTNER), the adhesive composition (4) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H838A, sold by Nan Ya Plastics Industry Co., Ltd.). Subsequently, the release film was placed in an oven and dried at 100 °C for 5 minutes and aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (4) disposed on a heavily peelable PET substrate was obtained.

[0095] Production Example 12 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Next, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Then, 175.0 g of the copolymer (5) - containing solution and 73.5 g of toluene were placed in a reaction flask. After thorough stirring and mixing, 1.04 g of the above - mentioned HMDI solution and 0.25 g of the above - mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (5) was obtained (solid content 40.1 wt%).

[0096] Using a scraper and a flow coater (model number ZAA2300, purchased from ZEHNTNER) with a gap of 420 μm and a width of 150 mm, the adhesive composition (5) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H338A, sold by Nan Ya Plastics Industry Co., Ltd.). Then, the release film was placed in an oven and dried at 100 °C for 5 minutes and aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (5) disposed on a lightly - peelable PET substrate was obtained.

[0097] Production Example 13 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Next, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Then, 175.0 g of the copolymer (6) - containing solution and 73.5 g of toluene were placed in a reaction flask. After thorough stirring and mixing, 1.54 g of the above - mentioned HMDI solution and 0.25 g of the above - mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (6) was obtained (solid content 40.1 wt%).

[0098] Using a scraper and a flow coater with a gap of 420 μm and a width of 150 mm (model number ZAA2300, purchased from ZEHNTNER), the adhesive composition (6) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H838A, sold by Nan Ya Plastics Industry Co., Ltd.). Subsequently, the release film was placed in an oven and dried at 100 °C for 5 minutes and then aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (6) disposed on a heavy release PET substrate was obtained.

[0099] Production Example 14 0.1 g of dibutyltin dilaurate (DBTDL) and 10 g of toluene were mixed to obtain a DBTDL solution. Subsequently, 1 g of hexamethylene diisocyanate (HMDI) and 9 g of toluene were mixed to obtain an HMDI solution. Next, 175.06 g of a copolymer (7) - containing solution and 55.8 g of toluene were placed in a reaction flask. After thoroughly stirring and mixing, 1.77 g of the above - mentioned HMDI solution and 0.25 g of the above - mentioned DBTDL solution were added to the reaction flask. After stirring for 30 minutes, an adhesive composition (7) was obtained (solid content 40.1 wt%).

[0100] Using a scraper and a flow coater with a gap of 420 μm and a width of 150 mm (model number ZAA2300, purchased from ZEHNTNER), the adhesive composition (7) was applied to a release film (polyethylene terephthalate (PET), thickness 38 μm, product code H338A, sold by Nan Ya Plastics Industry Co., Ltd.). Subsequently, the release film was placed in an oven and dried at 100 °C for 5 minutes and then aged at 70 °C for 18 hours. After cooling to room temperature and allowing to stand, an adhesive layer (7) disposed on a light release PET substrate was obtained.

[0101] Measurement of the properties of the adhesive layer The average thickness, average total transmittance, average haze, and average peel adhesion to glass at room temperature of the adhesive layers (1) - (7) were measured. The results are as shown in Table 2.

[0102] The measuring method for the average thickness of the adhesive layer was as follows. Using a micrometer (Micrometer, MITUTOYO IP65), the total thickness of six points of the adhesive layer including the release film was measured, and then the average value of the six points was taken as the average total thickness. The thickness of the release film was subtracted from the average total thickness to obtain the average thickness of the adhesive layer.

[0103] The measuring methods for the total transmittance and haze of the adhesive layer were as follows. The adhesive layer including the release film was used as a test piece. The test piece was cut into a size of 45 mm in width and 75 mm in length, and a pressure roller weighing 2 kg was rolled back and forth to press the release film. After the adhesive layer was pressed onto an optical glass substrate (thickness 0.7 mm), the release film was peeled off to make a measurement test piece of the adhesive layer / optical glass. The measuring methods for the total transmittance and haze were based on the methods specified in ASTM D1003, and the measuring instrument was a haze meter (NDH 2000, Nippon Denshoku). In the measuring step, first, an optical glass substrate calibration instrument was used to measure the total transmittance and haze of the test piece. After measuring three points for each test piece, the average value of the three points was taken as the average measured value of the test piece.

[0104] Peel adhesion of the adhesive layer to glass: The adhesive layer including the release film was cut into a strip film with a width of 25 mm and a length of 100 mm, and a pressure roller weighing 2 kg was rolled back and forth once to press the strip film. The adhesive layer was pressure-bonded and attached to a polyethylene terephthalate (PET) substrate (thickness 100 μm, product code SHINPEX O, sold by Shinco Optoelectronics) treated with a primer. Then, the release film was peeled off, and the adhesive layer was transferred to the polyethylene terephthalate substrate. Next, the adhesive layer was attached to a glass plate with a thickness of 1.8 mm, and a pressure roller weighing 2 kg was rolled back and forth once to press the polyethylene terephthalate substrate, obtaining a test piece of polyethylene terephthalate substrate / adhesive layer / glass plate. After leaving the test piece standing at room temperature for 24 hours, the peel adhesion of the test piece was measured. The measurement method of the peel adhesion followed ASTM D3330, and the measurement conditions were as follows. Using a tensile testing machine (model number QC-506B1, Cometech), the angle for peeling off the polyethylene terephthalate substrate was 180 o The peeling speed was set at 300 mm / min.

[0105]

Table 2

[0106] As can be seen from the results in Table 2, the physical properties of the adhesive layers (1) to (7) prepared with the adhesive compositions (1) to (7) all reached the physical property level of commercial optical adhesives (the peel adhesion at room temperature all maintained 1,400 gf / 25 mm or more, the total transmittance was all close to complete transmittance, and the haze was all less than 0.3%).

[0107] Fabrication of the double-sided adherend

[0108] Example 1 The adhesive layer (1) disposed on the lightly peelable PET substrate and the adhesive layer (2) disposed on the heavily peelable PET substrate were joined, and the adhesive layer (1) and the adhesive layer (2) were brought into contact with each other. Then, a pressure roller weighing 2 kg was rolled back and forth on the PET substrate for pressing to obtain a laminate including the double-sided adhesive body (1) (this laminate structure is: lightly peelable PET substrate / adhesive layer (1) / adhesive layer (2) / heavily peelable PET substrate).

[0109] The average thickness of the double-sided adhesive body (1) was measured. The results are as shown in Table 3.

[0110] The measuring method for the average thickness of the double-sided adhesive body was as follows. Using a micrometer (Micrometer, MITUTOYO IP65), the total thickness of six points of the laminate including the lightly peelable PET substrate and the heavily peelable PET substrate release film was measured, and then the numerical value obtained by averaging the six points was taken as the average total thickness. The thicknesses of the lightly peelable PET substrate and the heavily peelable PET substrate release film were subtracted from the average total thickness to obtain the average thickness of the adhesive layer.

[0111] Example 2 The adhesive layer (3) disposed on the lightly peelable PET substrate and the adhesive layer (4) disposed on the heavily peelable PET substrate were joined, and the adhesive layer (3) and the adhesive layer (4) were brought into contact with each other. Then, a pressure roller weighing 2 kg was rolled back and forth on the lightly peelable PET substrate for pressing to obtain a laminate including the double-sided adhesive body (2) (this laminate structure is: lightly peelable PET substrate / adhesive layer (3) / adhesive layer (4) / heavily peelable PET substrate).

[0112] The average thickness of the double-sided adhesive body (2) was measured. The results are as shown in Table 3.

[0113] Example 3 The adhesive layer (5) disposed on the lightly peelable PET substrate and the adhesive layer (6) disposed on the heavily peelable PET substrate were joined, and the adhesive layer (5) and the adhesive layer (6) were brought into contact with each other. Next, a pressure roller weighing 2 kg was rolled back and forth on the lightly peelable PET substrate to apply pressure, and a laminate including the double-sided adhesive body (3) was obtained (this laminate structure is: lightly peelable PET substrate / adhesive layer (5) / adhesive layer (6) / heavily peelable PET substrate).

[0114] The average thickness of the double-sided adhesive body (3) was measured. The results are as shown in Table 3.

[0115] Comparative Example 1 The adhesive layer (7) disposed on the lightly peelable PET substrate and the adhesive layer (4) disposed on the heavily peelable PET substrate were joined, and the adhesive layer (7) and the adhesive layer (4) were brought into contact with each other. Next, a pressure roller weighing 2 kg was rolled back and forth on the lightly peelable PET substrate to apply pressure, and a laminate including the double-sided adhesive body (4) was obtained (this laminate structure is: lightly peelable PET substrate / adhesive layer (7) / adhesive layer (4) / heavily peelable PET substrate).

[0116] The average thickness of the double-sided adhesive body (4) was measured. The results are as shown in Table 3.

[0117]

Table 3

[0118] Fabrication of Multilayer Structure and Reworkability Test

[0119] Example 4 A polarizing plate with a structure of protective film / polarizing film / pressure-sensitive adhesive / release film (size 45 mm × 75 mm, model number of the polarizing film is MIC25518, sold by Litek Optoelectronics) was prepared, and the protective film was peeled off in preparation for use. A laminate containing the double-sided adhesive body (1) described in Example 1 was prepared and cut to obtain a rectangular film piece (size 45 mm × 75 mm). Next, the lightly peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (1) of the rectangular film. Then, a glass plate (thickness 1.8 mm) was prepared, the adhesive layer (1) of the rectangular film piece was attached to the glass plate, and a pressure roller weighing 2 kg was rolled back and forth to press the heavily peeled PET substrate of the rectangular film piece. Next, the heavily peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (2) of the rectangular film piece. Then, the adhesive layer (2) of the rectangular film piece was attached to the polarizing film of the polarizing plate (structure: polarizing film / pressure-sensitive adhesive / release film), and a pressure roller weighing 2 kg was rolled back and forth to press the release film of the polarizing plate, obtaining a multilayer structure (1) (structure: glass plate / adhesive layer (1) / adhesive layer (2) / polarizing film / pressure-sensitive adhesive / release film).

[0120] After subjecting the multilayer structure (1) to a low-temperature treatment at -30°C for 30 minutes, the difference value between the adhesive force between the glass plate and the adhesive layer (1) and the adhesive force between the adhesive layer (2) and the polarizing film was evaluated. The results are as shown in Table 4. The measurement method of the peel adhesive force followed ASTM D3330.

[0121] Also, after subjecting the multilayer structure (1) to a low-temperature treatment at -30°C for 30 minutes, after peeling off the glass plate and the polarizing plate of the multilayer structure (1), the residual situation of the double-sided adhesive body (1) (adhesive layer (1) / adhesive layer (2)) on the glass plate and the polarizing film was examined. The results are as shown in Table 4.

[0122] Example 5 A polarizing plate with a structure of protective film / polarizing film / pressure-sensitive adhesive / release film (size 45 mm × 75 mm, model number of the polarizing film is MIC25518, sold by Litek Optoelectronics) was prepared, and the protective film was peeled off in preparation for use. A laminate including the double-sided adhesive body (2) described in Example 2 was prepared and cut to obtain a rectangular film piece (size 45 mm × 75 mm). Then, the lightly peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (3) of the rectangular film. Next, a glass plate (thickness 1.8 mm) was prepared, the adhesive layer (3) of the rectangular film piece was attached to the glass plate, and a pressure roller weighing 2 kg was rolled back and forth to press the heavily peeled PET substrate of the rectangular film piece. Then, the heavily peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (4) of the rectangular film piece. Next, the adhesive layer (4) of the rectangular film piece was attached to the polarizing film of the polarizing plate (structure: polarizing film / pressure-sensitive adhesive / release film), and a pressure roller weighing 2 kg was rolled back and forth to press the release film of the polarizing plate, obtaining a multilayer structure (2) (structure: glass plate / adhesive layer (3) / adhesive layer (4) / polarizing film / pressure-sensitive adhesive / release film).

[0123] After subjecting the multilayer structure (2) to a low-temperature treatment at -20°C for 30 minutes, the difference value between the adhesive force between the glass plate and the adhesive layer (3) and the adhesive force between the adhesive layer (4) and the polarizing film was evaluated. The results are as shown in Table 4. The measurement method of the peel adhesive force followed ASTM D3330.

[0124] Also, after subjecting the multilayer structure (2) to a low-temperature treatment at -20°C for 30 minutes, after peeling the glass plate and the polarizing plate of the multilayer structure (2), the residual situation in the glass plate and the polarizing film of the double-sided adhesive body (2) (adhesive layer (3) / adhesive layer (4)) was examined. The results are as shown in Table 4.

[0125] Example 6 A polarizing plate with a structure of protective film / polarizing film / pressure-sensitive adhesive / release film (size 45 mm × 75 mm, model number of the polarizing film is MIC25518, sold by Litek Optoelectronics) was prepared, and the protective film was peeled off in preparation for use. A laminate including the double-sided adhesive body (3) described in Example 3 was prepared and cut to obtain a rectangular film piece (size 45 mm × 75 mm). Next, the lightly peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (5) of the rectangular film. Then, a glass plate (thickness 1.8 mm) was prepared, the adhesive layer (5) of the rectangular film piece was attached to the glass plate, and a pressure roller weighing 2 kg was rolled back and forth to press the heavily peeled PET substrate of the rectangular film piece. Next, the heavily peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (6) of the rectangular film piece. Then, the adhesive layer (6) of the rectangular film piece was attached to the polarizing film of the polarizing plate (structure: polarizing film / pressure-sensitive adhesive / release film), and a pressure roller weighing 2 kg was rolled back and forth to press the release film of the polarizing plate, obtaining a multilayer structure (3) (structure: glass plate / adhesive layer (5) / adhesive layer (6) / polarizing film / pressure-sensitive adhesive / release film).

[0126] After the multilayer structure (3) was subjected to a low-temperature treatment at -40°C for 30 minutes, the difference value between the adhesive force between the glass plate and the adhesive layer (5) and the adhesive force between the adhesive layer (6) and the polarizing film was evaluated. The results are as shown in Table 4. The measurement method of the peel adhesive force followed ASTM D3330.

[0127] Also, after the multilayer structure (3) was subjected to a low-temperature treatment at -40°C for 30 minutes, after peeling the glass plate and the polarizing plate of the multilayer structure (3), the residual situation in the glass plate and the polarizing film of the double-sided adhesive body (3) (adhesive layer (5) / adhesive layer (6)) was examined. The results are as shown in Table 4.

[0128] Comparative Example 2 A polarizing plate with a structure of protective film / polarizing film / pressure-sensitive adhesive / release film (size 45 mm × 75 mm, model number of the polarizing film is MIC25518, sold by Litek Optoelectronics) was prepared, and the protective film was peeled off in preparation for use. A laminate including the double-sided adhesive body (4) described in Comparative Example 1 was prepared and cut to obtain a rectangular film piece (size 45 mm × 75 mm). Next, the lightly peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (7) of the rectangular film. Next, a glass plate (thickness 1.8 mm) was prepared, the adhesive layer (7) of the rectangular film piece was attached to the glass plate, and a pressure roller weighing 2 kg was rolled back and forth to press the heavily peeled PET substrate of the rectangular film piece. Next, the heavily peeled PET substrate of the rectangular film piece was peeled off to expose the adhesive layer (4) of the rectangular film piece. Next, the adhesive layer (4) of the rectangular film piece was attached to the polarizing film of the polarizing plate (structure: polarizing film / pressure-sensitive adhesive / release film), and a pressure roller weighing 2 kg was rolled back and forth to press the release film of the polarizing plate, obtaining a multilayer structure (4) (structure: glass plate / adhesive layer (7) / adhesive layer (4) / polarizing film / pressure-sensitive adhesive / release film).

[0129] After the multilayer structure (4) was subjected to a low-temperature treatment at -15°C for 30 minutes, the difference value between the adhesive force between the glass plate and the adhesive layer (7) and the adhesive force between the adhesive layer (4) and the polarizing film was evaluated. The results are as shown in Table 4. The measurement method of the peel adhesive force followed ASTM D3330.

[0130] Also, after the multilayer structure (4) was subjected to a low-temperature treatment at -15°C for 30 minutes, after peeling the glass plate and the polarizing plate of the multilayer structure (4), the residual situation in the glass plate and the polarizing film of the double-sided adhesive body (4) (adhesive layer (7) / adhesive layer (4)) was examined. The results are as shown in Table 4.

[0131]

Table 4

[0132] As can be seen from Table 4, in the multilayer structures fabricated using the double-sided adhesive body according to the present disclosure (for example, the multilayer structures (1) to (3) described in Examples 4 to 6), by adjusting the content (W1) of the third monomer (hard monomer) of the copolymer used to form the first adhesive layer and the content (W2) of the third monomer (hard monomer) of the copolymer used to form the second adhesive layer (i.e., W2 - W1 ≧ 7 wt%), after subjecting the multilayer structure to a low-temperature treatment, the difference in the adhesive strength between the first adhesive layer and the second adhesive layer could be increased. Thus, the glass plate and the polarizing plate could be easily peeled off, and the double-sided adhesive body did not remain on the polarizing film. On the other hand, in Comparative Example 2, the difference value between the content (W1) of the third monomer (hard monomer) of the copolymer used to form the first adhesive layer and the content (W2) of the third monomer of the copolymer used to form the second adhesive layer was only about 4.6 wt%. After subjecting the multilayer structure to a low-temperature treatment, no significant difference occurred in the adhesive strength between the first adhesive layer and the second adhesive layer. For this reason, when the glass plate and the polarizing plate were peeled off, it was observed that the double-sided adhesive body remained on both the glass plate and the polarizing film.

[0133] In summary, by controlling the difference in the content of the hard monomer in the first adhesive layer and the hard monomer in the second adhesive layer, after subjecting the double-sided adhesive body to a low-temperature treatment, the difference in the adhesion between the first adhesive layer and the second adhesive layer can be increased. If the double-sided adhesive body according to the present disclosure is used to bond a glass plate and a polarizing plate, the glass plate and the polarizing plate can be peeled off by a low-temperature treatment, and the adhesive material of the double-sided adhesive body does not remain on the polarizing plate. Therefore, the double-sided adhesive body of the present invention is suitable for use in the rework process of a display panel, can simplify the existing rework process, significantly shorten the time required for rework, and also omit the process of removing the residual adhesive on the polarizing plate. Accordingly, the polarizing plate is not damaged by removing the residual adhesive, and the reuse rate of the panel is increased.

[0134] It will be apparent that various modifications and variations can be made to the disclosed methods and materials. The specification and examples are intended to be regarded merely as illustrative, and the true scope of the disclosure is indicated by the following claims and their equivalents.

Explanation of Signs

[0135] 10…Double-sided adhesive body 11…First surface 12…First adhesive layer 13…Second surface 13 14…Second adhesive layer 20…First substrate 30…Second substrate 100…Multilayer structure

Claims

1. A first adhesive layer which is a product of a crosslinking reaction of a first adhesive composition, wherein the first adhesive composition includes a first copolymer and a first crosslinking agent, the first copolymer is a product of a copolymerization reaction of a first copolymer composition, the first copolymer composition includes a monomer (A1), the monomer (A1) includes a first monomer, a second monomer, and a third monomer, and in the monomer (A1), the weight percentage of the third monomer with respect to the weight of the monomer (A1) is W1, the first monomer is an acrylate monomer having a hydroxyl group, the second monomer is an acrylate monomer having a glass transition temperature of the homopolymer of -20°C or lower, and the third monomer is a monomer having a terminal vinyl group and a glass transition temperature of the homopolymer of 0°C or higher, the first adhesive layer; A second adhesive layer which is a product of a crosslinking reaction of a second adhesive composition, wherein the second adhesive composition includes a second copolymer and a second crosslinking agent, the second copolymer is a product of a copolymerization reaction of a second copolymer composition, the second copolymer composition includes a monomer (B1), the monomer (B1) includes a first monomer, a second monomer, and a third monomer, and in the monomer (B1), the weight percentage of the third monomer with respect to the weight of the monomer (B1) is W2, the second adhesive layer; comprising; 45 wt% ≥ W2 - W1 ≥ 7 wt%; having a first surface formed of the first adhesive layer and a second surface formed of the second adhesive layer; a double-sided adhesive body.

2. The double-sided adhesive body according to Claim 1, wherein in the monomer (A1), the weight percentage of the first monomer is from 1 wt% to 10 wt%, the weight percentage of the second monomer is from 50 wt% to 95 wt%, and the weight percentage of the third monomer is from 4 wt% to 49 wt%; in the monomer (B1), the weight percentage of the first monomer is from 1 wt% to 10 wt%, the weight percentage of the second monomer is from 50 wt% to 95 wt%, and the weight percentage of the third monomer is from 4 wt% to 49 wt%.

3. The first monomer is as follows: 【Chemical 1】 (wherein, R １ is hydrogen or a methyl group, and R ２ is hydrogen, or a C １－１０ alkylol group.) The second monomer is n-butyl acrylate, sec-butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, ethoxyethyl acrylate, isononyl acrylate, lauryl methacrylate, or a combination thereof, and the third monomer is tert-butyl acrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, methyl acrylate, methyl methacrylate, acrylonitrile, acrylamide, acryloyl morpholine, N-vinyl-2-pyrrolidone, or a combination thereof. The double-sided adhesive body according to claim 1.

4. The double-sided adhesive body according to claim 1, wherein a weight ratio of the first crosslinking agent to the first copolymer is from 1:5,000 to 5:100, and a weight ratio of the second crosslinking agent to the second copolymer is from 1:5,000 to 5:100.

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