A folding display device, an optical adhesive and a manufacturing method thereof

Abstract

This invention discloses a foldable display device, an optical adhesive, and a method for manufacturing the same. The foldable display device includes a first cover plate, a second cover plate, and a first adhesive layer. The first adhesive layer is located between the first and second cover plates, which are made of different materials. The first adhesive layer comprises a first adhesive layer and a second adhesive layer bonded together, with the first adhesive layer bonded to the second cover plate and the second adhesive layer bonded to the first cover plate. The first adhesive layer comprises a siloxane compound, and the surfaces of the first adhesive layer bonded to the second cover plate have siloxane bonds. These siloxane bonds have strong stability, allowing the first adhesive layer and the second cover plate to be firmly bonded together. The first adhesive layer includes two adhesive layers with different components, enabling it to simultaneously bond the first and second cover plates, which are made of different materials.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a foldable display device, an optical adhesive, and a method for manufacturing the same. Background Technology

[0002] Foldable display devices typically have multiple covers to protect the display components. These covers and the display components are bonded together using optical adhesive. To meet the folding requirements, the covers are usually made of polymer materials. However, this can lead to insufficient drop and impact resistance in foldable display devices. To address this issue, ultra-thin glass can be used instead of polymer materials as the covers. In this case, one side of the optical adhesive is a polymer material, and the other side is ultra-thin glass. Due to the significant difference in polarity between the different materials, one type of optical adhesive cannot simultaneously satisfy the bonding characteristics of both interfaces. This can easily lead to interface delamination during the folding process, thus affecting the performance and lifespan of the foldable display device. Summary of the Invention

[0003] This invention provides a foldable display device, an optical adhesive, and a method for manufacturing the same, so that the interface between different materials can have a better bonding effect and avoid the phenomenon of interface delamination.

[0004] In a first aspect, the present invention provides a folding display device, comprising: a first cover plate, a second cover plate, and a first adhesive layer; the first adhesive layer is located between the first cover plate and the second cover plate, and the first cover plate and the second cover plate are made of different materials;

[0005] The first adhesive layer includes a first adhesive layer and a second adhesive layer that are bonded to each other, and the first adhesive layer is bonded to the second cover plate, and the second adhesive layer is bonded to the first cover plate.

[0006] The first adhesive layer comprises a siloxane compound, and the surface on which the first adhesive layer is bonded to the second cover plate has siloxane bonds.

[0007] In some embodiments of the present invention, the first adhesive layer is made of siloxane, isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile.

[0008] The proportion of siloxane in the first adhesive layer is 3% to 40%; the proportion of isooctyl acrylate in the first adhesive layer is 5% to 90%; and the proportion of hydroxybutyl acrylate in the first adhesive layer is 5% to 45%.

[0009] In some embodiments of the present invention, the second adhesive layer is made of isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile.

[0010] The proportions of isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile in the first adhesive layer and the second adhesive layer are the same or at least partially different.

[0011] In some embodiments of the present invention, the proportion of octadecyl methacrylate in the second adhesive layer is greater than the proportion of octadecyl methacrylate in the first adhesive layer.

[0012] In some embodiments of the present invention, octadecyl methacrylate accounts for 1% to 5% of the second adhesive layer.

[0013] In some embodiments of the present invention, the storage modulus of the first adhesive layer and the second adhesive layer at a first temperature is both 25 kPa to 50 kPa, the storage modulus of the first adhesive layer at a second temperature is greater than 15 kPa, and the second temperature is higher than the first temperature; the storage modulus of the first adhesive layer and the second adhesive layer at a third temperature is both less than 100 kPa, and the third temperature is lower than the first temperature.

[0014] In some embodiments of the present invention, the adhesion of the first adhesive layer is greater than 1500 gf / 25 mm; the resilience of the first adhesive layer is greater than 85%.

[0015] In some embodiments of the present invention, the foldable display device further includes:

[0016] The second adhesive layer is located on the side of the second cover plate opposite to the first adhesive layer and is bonded to the second cover plate;

[0017] The second adhesive layer has the same composition as the first adhesive layer, and the surface on which the second adhesive layer is bonded to the second cover plate has siloxane bonds.

[0018] In some embodiments of the present invention, the first cover plate is made of polyimide or polyethylene terephthalate; the second cover plate is made of ultra-thin glass.

[0019] In some embodiments of the present invention, the foldable display device further includes:

[0020] The third cover plate is located on the side of the second adhesive layer opposite to the second cover plate and is bonded to the second adhesive layer; the third cover plate is made of one of polyimide, polyethylene terephthalate, thermoplastic polyurethane or polarizing film;

[0021] The third adhesive layer is located on the side of the third cover plate opposite to the second adhesive layer and is bonded to the third cover plate;

[0022] The display component is located on the side of the third adhesive layer opposite to the third cover plate and is bonded to the third adhesive layer;

[0023] A support component is located on the side of the display component opposite to the third adhesive layer.

[0024] In a second aspect, the present invention provides an optical adhesive, comprising: a heavy release film, an optical adhesive body, and a light release film; the optical adhesive body comprises a first adhesive layer and a second adhesive layer bonded together, the first adhesive layer being located on the surface of the heavy release film facing the light release film, and the second adhesive layer being located between the first adhesive layer and the light release film;

[0025] The first adhesive layer is made of siloxane, isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile; wherein, the proportion of siloxane in the first adhesive layer is 3% to 40%; the proportion of isooctyl acrylate in the first adhesive layer is 5% to 90%; and the proportion of hydroxybutyl acrylate in the first adhesive layer is 5% to 45%.

[0026] The second adhesive layer is made of isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile, wherein octadecyl methacrylate accounts for 1% to 5% of the second adhesive layer.

[0027] Thirdly, the present invention provides a method for manufacturing an optical adhesive, comprising:

[0028] A first adhesive material is coated onto the release film; the first adhesive material is a mixture of silicone, isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile in a predetermined ratio.

[0029] The first adhesive material is cured to form a first adhesive layer; the silicone in the first adhesive material is converted into a siloxane compound during curing;

[0030] A second adhesive material is coated on the first adhesive layer; the second adhesive material is isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid and azobisisobutyronitrile in a set ratio;

[0031] The second adhesive material is cured to form a second adhesive layer;

[0032] A light release film is applied to the second adhesive layer.

[0033] The beneficial effects of this invention are as follows:

[0034] This invention provides a foldable display device, an optical adhesive, and a method for manufacturing the same. The foldable display device includes a first cover plate, a second cover plate, and a first adhesive layer. The first adhesive layer is located between the first and second cover plates, which are made of different materials. The first adhesive layer includes a first adhesive layer and a second adhesive layer bonded together, with the first adhesive layer bonded to the second cover plate and the second adhesive layer bonded to the first cover plate. The first adhesive layer includes a siloxane compound, and the surfaces of the first adhesive layer bonded to the second cover plate have siloxane bonds. These siloxane bonds have strong stability, allowing the first adhesive layer and the second cover plate to be firmly bonded together. The first adhesive layer includes two different components, enabling it to simultaneously bond the first and second cover plates, which are made of different materials. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 One of the cross-sectional schematic diagrams of the foldable display device provided in the embodiment of the present invention;

[0037] Figure 2 This is a second cross-sectional schematic diagram of the foldable display device provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the structure of the optical adhesive provided in an embodiment of the present invention;

[0039] Figure 4 A flowchart illustrating the method for manufacturing optical adhesive according to an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram illustrating the manufacturing process of the optical adhesive provided in an embodiment of the present invention. Detailed Implementation

[0041] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the figures denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction in the present invention are illustrative based on the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of the present invention. The accompanying drawings of the present invention are for illustrative purposes only and do not represent actual proportions.

[0042] Foldable display devices consist of a multi-layered structure including a support structure, display components, and a cover plate to protect the display components. To meet the folding requirements, the cover plates of foldable display devices are typically made of polymer materials such as colorless polyimide (CPI) and polyethylene terephthalate (PET). The various cover plates and display components of a foldable display device are bonded together using optical adhesive. However, cover plates made of polymer materials often result in insufficient drop and impact resistance for foldable display devices. To solve this problem, ultra-thin glass (UTG) can be used as the cover material. Ultra-thin glass has advantages such as high strength, high hardness, strong wear resistance, and impact resistance, which can effectively protect the display device from scratches and breakage.

[0043] At this point, the two cover plates bonded by the optical adhesive may have one side made of polymer material and the other side made of ultra-thin glass. Due to the large difference in polarity between the different materials, a single optical adhesive cannot simultaneously satisfy the bonding characteristics of the two interfaces, which may cause the interface to delaminate during the folding process of the folding display device, thereby affecting the performance and service life of the folding display device.

[0044] In view of this, embodiments of the present invention provide a foldable display device in which the adhesive layer can simultaneously and effectively bond two cover plates of different materials, avoiding interface delamination.

[0045] Figure 1 This is one of the cross-sectional schematic diagrams of a foldable display device provided in an embodiment of the present invention.

[0046] like Figure 1As shown, the folding display device provided in this embodiment of the invention may include a first cover plate 110, a second cover plate 120, and a first adhesive layer 210. The first cover plate 110 and the second cover plate 120 are made of different materials. For example, the first cover plate 110 may be made of a polymer material such as CPI or PET, while the second cover plate 120 may be made of ultra-thin glass (UTG).

[0047] The first adhesive layer 210 is located between the first cover plate 110 and the second cover plate 120, and is used to bond the first cover plate 110 and the second cover plate 120. Specifically, the first adhesive layer 210 may include a first adhesive layer 211 and a second adhesive layer 212 that are bonded to each other. The first adhesive layer 211 is bonded to the second cover plate 120, and the second adhesive layer 212 is bonded to the first cover plate 110. The first adhesive layer 211 includes a siloxane compound, which can react with moisture in the air to form siloxane bonds. These chemical bonds are very stable and have strong adhesive ability. In this embodiment of the invention, the surfaces on which the first adhesive layer 211 and the second cover plate 120 are bonded have siloxane bonds, so that the first adhesive layer 211 and the second cover plate 120 can be firmly bonded together. When the second cover plate 120 is made of ultra-thin glass, the glass surface also has siloxane bonds, which can further improve the bonding strength between the first adhesive layer 211 and the second cover plate 120.

[0048] In this embodiment of the invention, the first adhesive layer 210 has two different adhesive layers. The materials and material ratios of each adhesive layer are designed according to the different materials of the cover plate. The two adhesive layers can be used to bond the cover plates of two different materials respectively, and the two adhesive layers are bonded to each other. This allows the first adhesive layer 210 to simultaneously meet the bonding characteristics of the first cover plate 110 and the second cover plate 120, thereby improving the bonding strength of the first cover plate 110 and the second cover plate 120. As a result, during the folding process of the folding display device, the interface delamination phenomenon between the first cover plate 110 and the second cover plate 120 is not likely to occur, which can improve the stability and service life of the folding display device.

[0049] In this embodiment of the invention, the first adhesive layer 211 may be made of silicone, 2-Ethylhexyl acrylate (2-EHA), hydroxybutyl acrylate (HBA), stearyl methyl acrylate (SMA), acrylic acid (AA), or azobisisobutyronitrile (AIBN). Silicone is a type of hard monomer that can give the adhesive a strong bond with the glass. 2-EHA is a type of main monomer that can provide the adhesive with a low storage modulus, which is helpful for the deformation of the adhesive layer. HBA is a type of functional monomer that can improve the crosslinking and curing properties of the adhesive.

[0050] The table below shows the test results of various characteristic parameters of the above materials under different proportions:

[0051]

[0052]

[0053] Wherein, G' represents the storage modulus, Tg represents the critical temperature point for the glass transition of the adhesive, and Recovery represents the resilience of the adhesive. During the curing of the adhesive, the silicone will react and transform into the aforementioned siloxane compound.

[0054] The above shows the peeling force of the adhesive material to the CPI interface and UTG interface, the storage modulus of the adhesive material at the first temperature (room temperature 25℃) and the second temperature (high temperature 60℃), the critical temperature for glass transition of the adhesive material, the resilience of the adhesive material, and the status of the display device under the conditions of dynamic bending 200,000 times at room temperature and bending for 240 hours under high temperature and high humidity. OK indicates that the display device is normal, and NG indicates that interface delamination occurs in the display device and bending failure occurs.

[0055] As shown in the table above, in one feasible embodiment, the first adhesive layer 211 contains 86.5% 2-EHA, 10% HBA, 2.5% siloxane, 0% SMA, 1% AA, and 0.05% AIBN; the first adhesive layer 211 has an adhesion force greater than 1700 gf / 25 mm to CPI and greater than 1900 gf / 25 mm to UTG; the first adhesive layer 211 has a storage modulus of 33 kPa at a first temperature (room temperature 25°C) and a storage modulus of 19 kPa at a second temperature (high temperature 60°C); the Tg point of the first adhesive layer 211 is -41°C; and the resilience of the first adhesive layer 211 is 88%.

[0056] Based on experimental and test results, the embodiments of the present invention can provide the following specific proportions of each material in the first adhesive layer 211: The proportion of siloxane converted from silicone during the curing process in the first adhesive layer 211 is 3%–40%, optionally, the proportion of siloxane in the first adhesive layer 211 is 5%–15%, optionally, the proportion of siloxane in the first adhesive layer 211 is 2.5%, 3%, 5%, 15%, or 40%; the proportion of isooctyl acrylate (2-EHA) in the first adhesive layer 211 is 5%–90%, optionally, the proportion of 2-EHA in the first adhesive layer 211 is 50%–90%, optionally, 2-EHA… The proportions of the components in the first adhesive layer 211 are 5%, 50%, 84.55%, 86.5%, 89%, and 90%; the proportion of hydroxybutyl acrylate (HBA) in the first adhesive layer 211 is 5% to 45%, optionally, the proportion of HBA in the first adhesive layer 211 is 5% to 20%, optionally, the proportion of HBA in the first adhesive layer 211 is 5%, 10%, 20%, and 45%; optionally, the proportion of SMA in the first adhesive layer 211 is 4.45%; optionally, the proportion of AA in the first adhesive layer 211 is 1%; optionally, the proportion of AIBN in the first adhesive layer 211 is 0.05% and 0.08%.

[0057] Based on the above ratio, the adhesion of the first adhesive layer 211 is greater than 1500gf / 25mm, which can help avoid the interface delamination phenomenon between the first adhesive layer 211 and the second cover plate 120; the resilience of the first adhesive layer 211 is greater than 85%, which can ensure that the display device does not experience cohesive failure during folding; the energy storage modulus of the first adhesive layer 211 is 25kPa to 50kPa at the first temperature (room temperature 25℃), greater than 15kPa at the second temperature (high temperature 60℃), and less than 100kPa at the third temperature (low temperature -20℃), which can meet the folding performance requirements of the display device.

[0058] In summary, the first adhesive layer 211 can simultaneously possess good adhesion, good bending ability, high hardness, and good recovery performance, and can also have high bonding strength with the glass interface.

[0059] In this embodiment of the invention, the second adhesive layer 212 may be made of isooctyl acrylate (2-EHA), hydroxybutyl acrylate (HBA), octadecyl methacrylate (SMA), acrylic acid (AA), or azobisisobutyronitrile (AIBN). The table below shows the test results of various characteristic parameters of the above materials at different ratios:

[0060]

[0061] The above shows the peeling force of the adhesive material to the CPI interface and UTG interface, the storage modulus of the adhesive material at the first temperature (room temperature 25℃) and the second temperature (high temperature 60℃), the critical temperature for glass transition of the adhesive material, the resilience of the adhesive material, and the state of the display device under the conditions of dynamic bending 200,000 times at room temperature and bending for 240 hours under high temperature and high humidity.

[0062] Based on experimental and test results, the embodiments of the present invention can provide the proportions of each material in the second adhesive layer 212, wherein the proportions of isooctyl acrylate (2-EHA), hydroxybutyl acrylate (HBA), octadecyl methacrylate (SMA), and azobisisobutyronitrile (AIBN) in the first adhesive layer 211 and the second adhesive layer 212 can be the same or at least partially different.

[0063] As shown in the table above, in one feasible embodiment, the proportion of 2-EHA is 85.5%, the proportion of HBA is 10%, the proportion of SMA is 3%, the proportion of AA is 1%, and the proportion of AIBN is 0.05%; the adhesion of the second adhesive layer 212 to CPI is greater than 1700gf / 25mm, and the adhesion to UTG is greater than 1100gf / 25mm; the storage modulus of the second adhesive layer 212 at the first temperature (room temperature 25℃) is 33kPa, and the storage modulus at the second temperature (high temperature 60℃) is 19kPa; the Tg point of the second adhesive layer 212 is -41℃; and the resilience of the second adhesive layer 212 is 91%.

[0064] In one feasible embodiment, the proportion of 2-EHA is 87.5%, the proportion of HBA is 10%, the proportion of SMA is 2%, the proportion of AA is 1%, and the proportion of AIBN is 0.05%; the adhesion of the second adhesive layer 212 to CPI is greater than 2100gf / 25mm, and the adhesion to UTG is greater than 1350gf / 25mm; the storage modulus of the second adhesive layer 212 is 32kPa at a first temperature (room temperature 25°C), and the storage modulus is 17kPa at a second temperature (high temperature 60°C); the Tg point of the second adhesive layer 212 is -39°C; and the resilience of the second adhesive layer 212 is 89.2%.

[0065] In one feasible embodiment, the proportion of 2-EHA is 84.55%, the proportion of HBA is 10%, the proportion of SMA is 4.45%, the proportion of AA is 1%, and the proportion of AIBN is 0.08%; the adhesion of the second adhesive layer 212 to CPI is greater than 1850 gf / 25 mm, and the adhesion to UTG is greater than 846 gf / 25 mm; the storage modulus of the second adhesive layer 212 at a first temperature (room temperature 25°C) is 32.1 kPa, and the storage modulus at a second temperature (high temperature 60°C) is 18.5 kPa; the Tg point of the second adhesive layer 212 is -39.56°C; and the resilience of the second adhesive layer 212 is 88.4%.

[0066] In this embodiment of the invention, the proportion of SMA in the second adhesive layer 212 is greater than that in the first adhesive layer 211. Specifically, the proportion of SMA in the second adhesive layer 212 can be 1% to 5%, optionally 1%, 2%, 3%, 4.45%, or 5%. Optionally, the proportion of 2-EHA in the second adhesive layer 212 can be 85.5%, 87.5%, or 84.55%. Optionally, the proportion of HBA in the second adhesive layer 212 can be 10%. Optionally, the proportion of AA in the second adhesive layer 212 can be 1%. Optionally, the proportion of AIBN in the second adhesive layer 212 can be 0.05% or 0.08%. In this embodiment of the invention, an ultra-low Tg point SMA material is added to the adhesive material of the second adhesive layer 212, which can lower the Tg point of the adhesive material used in the second adhesive layer 212 to -50°C, exhibiting ultra-low bending characteristics, which is beneficial for improving the folding capability of the display device.

[0067] Based on the above ratio, the energy storage modulus of the second adhesive layer 212 is 25kPa to 50kPa at the first temperature (room temperature 25℃), and the energy storage modulus is less than 100kPa at the third temperature (low temperature -20℃). The second adhesive layer 212 can meet the requirements of the folding characteristics of the display device.

[0068] Figure 2 This is a second cross-sectional schematic diagram of the folding display device provided in an embodiment of the present invention.

[0069] like Figure 1 and Figure 2 As shown in the embodiment of the present invention, the folding display device may further include a second adhesive layer 220, a display component 300, and a support component 400. The second adhesive layer 220 is located on the side of the second cover plate 120 opposite to the first adhesive layer 210 and is bonded to the second cover plate 120. When the second cover plate 120 uses UTG, the components of the second adhesive layer 220 and the first adhesive layer 210 may be the same. The surface where the second adhesive layer 220 is bonded to the second cover plate 120 has siloxane bonds, thereby enabling it to bond firmly to the glass interface.

[0070] like Figure 2 As shown, the folding display device may also include a third cover plate 130 and a third adhesive layer 230.

[0071] The third cover plate 130 is located on the side of the second adhesive layer 220 opposite to the second cover plate 120 and is bonded to the second adhesive layer 220. The third cover plate 130 is made of one of colorless polyimide (CPI), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU), or polarizing film (CPOL). The second adhesive layer 220 has the same components as the first adhesive layer 210, wherein the adhesive layer with siloxane bonds can be used to bond the second cover plate 120, and the adhesive layer without siloxane bonds can be used to bond the third cover plate 130.

[0072] The third adhesive layer 230 is located on the side of the third cover plate 130 away from the second adhesive layer 220 and is bonded to the third cover plate 130. Since the third cover plate 130 is made of polymer material or polarizer, the third adhesive layer 230 does not need to be bonded to UTG. Therefore, the third adhesive layer 230 can use conventional optical adhesive.

[0073] The display component 300 is located on the side of the third adhesive layer 230 away from the third cover plate 130 and is bonded to the third adhesive layer 230. The display component 300 may be an organic light-emitting diode (OLED) display component 300 or the like. The display component 300 is used to realize the display function. The specific type and structure of the display component 300 are not limited in this embodiment of the invention.

[0074] The support assembly 400 is located on the side of the display assembly 300 opposite to the third adhesive layer 230, and may include at least one support member. The support member on the side of the support assembly 400 further away from the display assembly 300 may have higher rigidity. For example, the support assembly 400 may include a first support layer 410 and a second support layer 420, wherein the second support layer 420 is located on the side of the first support layer 410 opposite to the display assembly 300. The first support layer 410 may be made of materials such as PET or PI, and the second support layer 420 may be made of materials such as carbon, metal, or alloy. The support assembly 400 can be used to support the multi-layer structure disposed above it in a foldable display device, and also provides protection. In specific implementations, the specific shape of the support assembly 400, the number of its support members, and the materials used can be designed according to requirements, and this embodiment of the invention is not limited thereto.

[0075] Based on the same inventive concept, embodiments of the present invention also provide an optical adhesive.

[0076] Figure 3This is a schematic diagram of the structure of the optical adhesive provided in an embodiment of the present invention.

[0077] like Figure 3 As shown, the optical adhesive includes a heavy release film 10, an optical adhesive body 20, and a light release film 30. The optical adhesive body 20 includes a first adhesive layer 211 and a second adhesive layer 212 bonded together. The first adhesive layer 211 is located on the surface of the heavy release film 10 facing the light release film 30, and the second adhesive layer 212 is located between the first adhesive layer 211 and the light release film 30. When applying the optical adhesive to a display device, the release films on both sides of the optical adhesive body need to be removed first.

[0078] In the optical adhesive matrix, the first adhesive layer 211 is made of siloxane, isooctyl acrylate (2-EHA), hydroxybutyl acrylate (HBA), octadecyl methacrylate (SMA), acrylic acid (AA), and azobisisobutyronitrile (AIBN). Specifically, the proportion of siloxane in the first adhesive layer 211 is 3%–40%; the proportion of 2-EHA in the first adhesive layer 211 is 5%–90%; and the proportion of HBA in the first adhesive layer 211 is 5%–45%.

[0079] The second adhesive layer 212 is made of isooctyl acrylate (2-EHA), hydroxybutyl acrylate (HBA), octadecyl methacrylate (SMA), acrylic acid (AA), and azobisisobutyronitrile (AIBN), wherein SMA accounts for 1% to 5% of the second adhesive layer 212.

[0080] Based on the above ratio, the first adhesive layer 211 of the optical adhesive can be used to bond glass interfaces, and the second adhesive layer 212 can be used to bond polymer material interfaces. The optical adhesive can simultaneously satisfy the bonding characteristics of both interfaces and has good bonding ability and folding performance.

[0081] Based on the same inventive concept, this invention also provides a method for manufacturing an optical adhesive. In this invention, the optical adhesive can be manufactured using a coating process or an inkjet printer (IJP) process, and its curing method can include thermal curing or ultraviolet (UV) curing. The manufacturing process of the optical adhesive manufactured using a coating process is described below.

[0082] Figure 4 A flowchart illustrating the method for manufacturing optical adhesive according to an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the manufacturing process of the optical adhesive provided in an embodiment of the present invention.

[0083] like Figure 4 As shown, the manufacturing process of optical adhesive includes the following steps:

[0084] S1. Coat the first adhesive material onto the release film;

[0085] S2. Curing the first adhesive material to form the first adhesive layer;

[0086] S3. Apply the second adhesive material onto the first adhesive layer;

[0087] S4. Cure the second adhesive material to form the second adhesive layer;

[0088] S5. Cover the second adhesive layer with a light release film.

[0089] Specifically, in step S1, a release film 10 can be formed by coating a release agent onto a base film, such as a PET film; the first adhesive material is a mixture of silicone, 2-EHA, HBA, SMA, AA, and AIBN in a predetermined ratio, wherein the proportion of silicone can be 3%–40%, the proportion of 2-EHA can be 5%–90%, and the proportion of HBA can be 5%–45%. Step S1 corresponds to… Figure 5 (a) and Figure 5 (b) includes a first base film 11, a first release agent 12 and a first adhesive 21, wherein the first base film 11 and the first release agent 12 constitute a heavy release film 10.

[0090] In step S2, the first adhesive material 21 can be cured by UV light. During curing, the silicone in the first adhesive material 21 can be converted into a siloxane compound. Step S2 corresponds to... Figure 5 (c) After completing step S2, the first adhesive layer 211 can be formed.

[0091] In step S3, the second adhesive material is a mixture of 2-EHA, HBA, SMA, AA, and AIBN in a predetermined ratio, wherein the proportion of SMA can be 1% to 5%. Step S3 corresponds to... Figure 5 (d) The second adhesive material 22 is coated on the first adhesive layer 211.

[0092] In step S4, the second adhesive material 22 is cured using UV light. Step S3 corresponds to... Figure 5 (e) After completing step S4, a second adhesive layer 212 can be formed.

[0093] In step S5, a light release film 30 can be formed by coating a release agent onto a base film, such as a PET film. Step S5 corresponds to... Figure 5 (f) The light release film 30 includes a second base film 31 and a second release agent 32, and the light release film 30 covers the second adhesive layer 212.

[0094] The following is a specific production method as an example:

[0095] Mix 86.5g of 2-EHA, 10g of HBA, 2.5g of silicone, 1g of AA, and 0.04g of D1173 photoinitiator in a transparent wide-mouth glass bottle; purge the bottle with nitrogen for 5-8 minutes until all air is expelled; irradiate the mixture with UV light until the viscosity reaches 1800-2300 cP. A low-intensity UV light from a 360nm LED lamp can be used for UV irradiation; turn off the UV lamp and purge with air to stop polymerization, forming the first mixed solution.

[0096] Mix 85.5g of 2-EHA, 10g of HBA, 3g of SMA, 1g of AA, and 0.04g of D1173 photoinitiator in a transparent wide-mouth glass bottle; purge the bottle with nitrogen for 5-8 minutes until all air is expelled; irradiate the mixture with UV light until the viscosity reaches 1800-2300 cP. A low-intensity UV light from a 360nm LED lamp can be used for UV irradiation; turn off the UV lamp and purge with air to stop polymerization, forming a second mixed solution.

[0097] Add 0.05g of AIBN to the first mixed solution, and apply the solution to the surface of the release film 10 using a doctor blade coater. Then, irradiate it with UV light to form the first adhesive layer 211. At this time, the UV intensity can be 1200mJ / cm. 2 Irradiation; similarly, the second solution is coated to form the second adhesive layer 212, and then a light release film 30 is covered on the second adhesive layer 212, and the preparation process is completed by winding.

[0098] The optical adhesive produced by the above method can have high adhesion and interfacial peeling force to both the UTG interface and the polymer material interface, and can meet the energy storage modulus requirements of foldable display folding performance. When applied to foldable display devices, it can avoid the phenomenon of interface delamination.

[0099] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0100] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A foldable display device, characterized in that, include: A first cover plate, a second cover plate, and a first adhesive layer; the first adhesive layer is located between the first cover plate and the second cover plate, and the first cover plate and the second cover plate are made of different materials; The first adhesive layer includes a first adhesive layer and a second adhesive layer that are bonded to each other, and the first adhesive layer is bonded to the second cover plate, and the second adhesive layer is bonded to the first cover plate. The first adhesive layer comprises a siloxane compound, and the surface on which the first adhesive layer is bonded to the second cover plate has siloxane bonds; The first adhesive layer is made of siloxane, wherein the proportion of siloxane in the first adhesive layer is 3% to 40%; the adhesion of the first adhesive layer is greater than 1500gf / 25mm.

2. The folding display device as claimed in claim 1, characterized in that, The first adhesive layer is made of siloxane, isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile. The proportion of isooctyl acrylate in the first adhesive layer is 5% to 90%; the proportion of hydroxybutyl acrylate in the first adhesive layer is 5% to 45%.

3. The folding display device as described in claim 2, characterized in that, The second adhesive layer is made of isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile. The proportions of isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile in the first adhesive layer and the second adhesive layer are the same or at least partially different.

4. The folding display device as described in claim 3, characterized in that, The proportion of octadecyl methacrylate in the second adhesive layer is greater than that in the first adhesive layer.

5. The folding display device as claimed in claim 4, characterized in that, The proportion of octadecyl methacrylate in the second adhesive layer is 1% to 5%.

6. The folding display device as claimed in claim 1, characterized in that, The storage modulus of the first adhesive layer and the second adhesive layer at the first temperature is both 25 kPa to 50 kPa. The storage modulus of the first adhesive layer at the second temperature is greater than 15 kPa, and the second temperature is higher than the first temperature. The storage modulus of the first adhesive layer and the second adhesive layer at the third temperature is both less than 100 kPa, and the third temperature is lower than the first temperature.

7. The folding display device as claimed in claim 1, characterized in that, The resilience of the first adhesive layer is greater than 85%.

8. The folding display device according to any one of claims 1 to 7, characterized in that, Also includes: The second adhesive layer is located on the side of the second cover plate opposite to the first adhesive layer and is bonded to the second cover plate; The second adhesive layer has the same composition as the first adhesive layer, and the surface on which the second adhesive layer is bonded to the second cover plate has siloxane bonds.

9. The folding display device as claimed in claim 8, characterized in that, The first cover plate is made of polyimide or polyethylene terephthalate; the second cover plate is made of ultra-thin glass.

10. The folding display device as claimed in claim 8, characterized in that, Also includes: The third cover plate is located on the side of the second adhesive layer opposite to the second cover plate and is bonded to the second adhesive layer; The third cover plate is made of one of polyimide, polyethylene terephthalate, thermoplastic polyurethane, or polarizing film. The third adhesive layer is located on the side of the third cover plate opposite to the second adhesive layer and is bonded to the third cover plate; The display component is located on the side of the third adhesive layer opposite to the third cover plate and is bonded to the third adhesive layer; A support component is located on the side of the display component opposite to the third adhesive layer.

11. An optical adhesive, characterized in that, include: A heavy release film, an optical adhesive body, and a light release film; the optical adhesive body includes a first adhesive layer and a second adhesive layer bonded together, the first adhesive layer being located on the surface of the heavy release film facing the light release film, and the second adhesive layer being located between the first adhesive layer and the light release film; The first adhesive layer is made of siloxane, isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile; wherein, the proportion of siloxane in the first adhesive layer is 3%~40%; the proportion of isooctyl acrylate in the first adhesive layer is 5%~90%; the proportion of hydroxybutyl acrylate in the first adhesive layer is 5%~45%; and the adhesion of the first adhesive layer is greater than 1500gf / 25mm. The second adhesive layer is made of isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid and azobisisobutyronitrile, wherein octadecyl methacrylate accounts for 1% to 5% of the second adhesive layer.

12. A method for manufacturing an optical adhesive, characterized in that, include: A first adhesive material is coated onto the release film; the first adhesive material is a mixture of silicone, isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid, and azobisisobutyronitrile in a predetermined ratio, wherein the proportion of silicone in the first adhesive material is 3% to 40%; The first adhesive material is cured to form a first adhesive layer; the silicone in the first adhesive material is converted into a siloxane compound during curing; the adhesion of the first adhesive layer is greater than 1500gf / 25mm; A second adhesive material is coated on the first adhesive layer; the second adhesive material is isooctyl acrylate, hydroxybutyl acrylate, octadecyl methacrylate, acrylic acid and azobisisobutyronitrile in a set ratio; The second adhesive material is cured to form a second adhesive layer; A light release film is applied to the second adhesive layer.

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