Flexible cover plate, preparation method thereof and display device

Abstract

The application provides a flexible cover plate, a preparation method thereof and a display device. By making the flexible cover plate include at least two substrate layers, and making the elastic modulus of the substrate layer close to the inner side of the bending of the flexible cover plate greater than the elastic modulus of the substrate layer far from the inner side of the bending of the flexible cover plate, the bending performance of the substrate layer far from the inner side of the bending of the flexible cover plate is better than the bending performance of the substrate layer close to the inner side of the bending of the flexible cover plate, and the surface hardness and impact resistance of the substrate layer close to the inner side of the bending of the flexible cover plate are better than the surface hardness and impact resistance of the substrate layer far from the inner side of the bending of the flexible cover plate. Therefore, when the flexible cover plate is attached to the display panel, the substrate layer with relatively lower elastic modulus in the flexible cover plate can be arranged on the outer side of the bending of the display device, and the substrate layer with relatively higher elastic modulus can be arranged on the inner side of the bending of the display device, so that the bending performance and surface hardness of the display device are considered.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a flexible cover plate, its preparation method, and a display device. Background Technology

[0002] OLED (Organic Light-Emitting Diode) displays are widely used due to their high brightness, wide viewing angle, fast response speed, ultra-thinness, light weight, and flexibility. To achieve flexibility in OLED displays, in addition to a flexible design for the display panel, a flexible cover plate is also required. Existing flexible cover plates consist of an organic substrate layer and a hardened coating. When the thickness of the flexible cover plate is low, its bending performance is good, but its surface hardness and impact resistance are poor. When the thickness of the flexible cover plate is high, its surface hardness and impact resistance are good, but its bending performance is poor, causing the various film layers in the flexible cover plate to break due to excessive internal stress during repeated bending.

[0003] Therefore, existing flexible cover plates have the technical problem of not being able to balance bending performance and surface hardness. Summary of the Invention

[0004] This application provides a flexible cover plate, its preparation method, and a display device to alleviate the technical problem that existing flexible cover plates cannot simultaneously achieve both bending performance and surface hardness.

[0005] This application provides a flexible cover plate that can be bent along a bend line. The flexible cover plate includes at least two substrate layers. In two adjacent substrate layers, the elastic modulus of the substrate layer closer to the inner side of the bend is greater than that of the substrate layer farther from the inner side of the bend, and the repeating structural units of the corresponding materials of each substrate layer are the same.

[0006] In some embodiments, the degree of polymerization of the substrate layer material near the inner side of the bend of the flexible cover is greater than the degree of polymerization of the substrate layer material away from the inner side of the bend of the flexible cover.

[0007] In some embodiments, in two adjacent substrate layers, the substrate layer closer to the inner side of the bend of the flexible cover plate is in direct contact with the substrate layer farther from the inner side of the bend of the flexible cover plate.

[0008] In some embodiments, when the flexible cover plate is bent inward, the flexible cover plate further includes a hardening layer, the hardening layer being disposed on the side of the substrate layer near the inner side of the bend of the flexible cover plate, and the elastic modulus of the hardening layer being greater than the elastic modulus of the substrate layer near the inner side of the bend of the flexible cover plate.

[0009] In some embodiments, when the flexible cover plate is bent outward, the flexible cover plate further includes a hardening layer, the hardening layer being disposed on the side of the substrate layer away from the inner side of the bend of the flexible cover plate, and the elastic modulus of the hardening layer being greater than the elastic modulus of the substrate layer near the inner side of the bend of the flexible cover plate.

[0010] In some embodiments, when the flexible cover plate is in a bent state, the elastic modulus of the multiple substrate layers increases in the direction from the outer side of the bend to the inner side of the bend.

[0011] In some embodiments, the difference in elastic modulus between adjacent substrate layers is less than or equal to 100 megapascals.

[0012] In some embodiments, the elastic modulus of the substrate layer on the inner side of the bend away from the flexible cover plate is greater than or equal to 4 gigapascals.

[0013] In some embodiments, the thickness of the substrate layer is greater than or equal to 10 micrometers.

[0014] In some embodiments, the thickness of the flexible cover plate ranges from 20 micrometers to 200 micrometers.

[0015] Meanwhile, this application provides a method for preparing a flexible cover plate. This method is used to prepare a flexible cover plate as described in any of the above embodiments. The method for preparing the flexible cover plate includes:

[0016] Polyethylene terephthalate particles of different molecular weights are placed into different feed ports, so that the polyethylene terephthalate particles of different molecular weights melt and flow from different channels into the same casting plate.

[0017] A flexible cover plate is obtained by stretching and cooling the molten polyethylene terephthalate.

[0018] In some embodiments, the average molecular weight of the substrate layer near the inner side of the bend of the flexible cover is greater than the average molecular weight of the substrate layer away from the inner side of the bend of the flexible cover.

[0019] Meanwhile, embodiments of this application provide a display device, which includes:

[0020] Display panel;

[0021] A flexible cover plate, which can be bent along a bend line, is disposed on one side of the display panel. The flexible cover plate includes at least two substrate layers. In two adjacent substrate layers, the elastic modulus of the substrate layer closer to the inner side of the bend of the flexible cover plate is greater than the elastic modulus of the substrate layer farther from the inner side of the bend of the flexible cover plate, and the repeating structural units of the corresponding materials of each substrate layer are the same.

[0022] An adhesive layer is disposed between the display panel and the flexible cover plate.

[0023] In some embodiments, when the bending direction of the display device is inward, the substrate layer on the inner side of the bend away from the flexible cover plate is disposed between the display panel and the substrate layer on the inner side of the bend near the flexible cover plate.

[0024] In some embodiments, when the bending direction of the display device is outward, the substrate layer near the inner side of the bend of the flexible cover plate is disposed between the display panel and the substrate layer away from the inner side of the bend of the flexible cover plate.

[0025] Beneficial effects: This application provides a flexible cover plate and its preparation method, as well as a display device; the flexible cover plate can be bent along a bending line, the flexible cover plate includes at least two substrate layers, in two adjacent substrate layers, the elastic modulus of the substrate layer closer to the inner side of the bend of the flexible cover plate is greater than the elastic modulus of the substrate layer farther from the inner side of the bend of the flexible cover plate, and the repeating structural units of the corresponding materials of each substrate layer are the same. This application incorporates at least two substrate layers into a flexible cover plate, with the elastic modulus of the substrate layer closer to the inner bend of the flexible cover plate being greater than that of the substrate layer farther from the inner bend. This results in superior bending performance for the substrate layer farther from the inner bend, and also superior surface hardness and impact resistance for the substrate layer closer to the inner bend. Therefore, when the flexible cover plate is bonded to the display panel, the substrate layer with a relatively lower elastic modulus can be positioned on the outer bend side of the display device, improving its bending performance and preventing failure due to excessive bending stress. Conversely, the substrate layer with a relatively higher elastic modulus can be positioned on the inner bend side of the display device, improving its surface hardness and impact resistance. This approach balances both the bending performance and surface hardness of the display device. Attached Figure Description

[0026] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0027] Figure 1 This is a first schematic diagram of a flexible cover plate provided in an embodiment of this application.

[0028] Figure 2 This is a second schematic diagram of the flexible cover plate provided in an embodiment of this application.

[0029] Figure 3 This is a third schematic diagram of the flexible cover plate provided in the embodiments of this application.

[0030] Figure 4 A flowchart illustrating the preparation method of the flexible cover plate provided in this application embodiment.

[0031] Figure 5 This is a schematic diagram of the apparatus for preparing a flexible cover plate according to an embodiment of this application.

[0032] Figure 6 This is a first schematic diagram of a display device provided in an embodiment of this application.

[0033] Figure 7 This is a second schematic diagram of a display device provided in an embodiment of this application.

[0034] Figure 8 This is a third schematic diagram of a display device provided in an embodiment of this application.

[0035] Figure 9 This is a fourth schematic diagram of a display device provided in an embodiment of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0037] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0038] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0041] This application addresses the technical problem that existing flexible cover plates cannot simultaneously achieve both bending performance and surface hardness, by providing a flexible cover plate and a display device to alleviate the aforementioned technical problems.

[0042] like Figure 1 As shown, this application embodiment provides a flexible cover plate 1 that can be bent along a bending line. The flexible cover plate 1 includes at least two substrate layers (e.g., a first substrate layer 11 and a second substrate layer 12). In two adjacent substrate layers, the elastic modulus of the substrate layer (e.g., the first substrate layer 11) closer to the inner side of the bend of the flexible cover plate is greater than the elastic modulus of the substrate layer (e.g., the second substrate layer 12) farther away from the inner side of the bend of the flexible cover plate. Moreover, the repeating structural units of the materials corresponding to each substrate layer are the same (e.g., the repeating structural units of the materials corresponding to each substrate layer are all repeating structural units of polyethylene terephthalate).

[0043] This application provides a flexible cover plate comprising at least two substrate layers. The elastic modulus of the substrate layer near the inner side of the bend is greater than that of the substrate layer away from the inner side of the bend. Therefore, the bending performance of the substrate layer away from the inner side of the bend is superior to that of the substrate layer near the inner side of the bend. Furthermore, the surface hardness and impact resistance of the substrate layer near the inner side of the bend are superior to those of the substrate layer away from the inner side of the bend. When the flexible cover plate is bonded to a display panel, the substrate layer with a relatively lower elastic modulus can be positioned on the outer side of the bend of the display device, improving the bending performance of the display device and preventing failure due to excessive bending stress. Conversely, the substrate layer with a relatively higher elastic modulus can be positioned on the inner side of the bend, improving the surface hardness and impact resistance of the display device. This approach balances the bending performance and surface hardness of the display device.

[0044] Specifically, for ease of explanation, the following embodiments are illustrated by taking the first substrate layer as the substrate layer on the inner side of the bend closest to the flexible cover plate and the second substrate layer as the substrate layer on the inner side of the bend away from the flexible cover plate as examples.

[0045] Specifically, such as Figure 1 The flexible cover plate 1 includes a first substrate layer 11 and a second substrate layer 12 disposed adjacent to each other. The first substrate layer 11 is close to the inner side of the bend of the flexible cover plate 1, and the second substrate layer 12 is far away from the inner side of the bend of the flexible cover plate 1. By making the elastic modulus of the first substrate layer 11 greater than that of the second substrate layer 12, the flexible cover plate can take into account both the bending performance and surface hardness of the display device.

[0046] Specifically, if the elastic modulus of each substrate layer in a current flexible cover plate is the same, the performance of each substrate layer in the flexible cover plate will be similar or even the same. For example, each substrate layer may have good bending performance, but poor surface hardness and impact resistance. This makes it easy to leave scratches or dents on the flexible cover plate when using display devices, resulting in poor appearance of the display devices and damage to the film layers inside the display panel, leading to display failure. On the other hand, if the surface hardness and impact resistance of each substrate layer are good, the bending performance of each substrate layer is poor. This makes it easy for the flexible cover plate to bend and break when using display devices, leading to display device failure. In this embodiment, by varying the elastic modulus of the substrate layers with the same repeating structural units of corresponding materials in the flexible cover plate, the performance of different substrate layers differs. Specifically, the elastic modulus of the substrate layer closer to the inner bend of the flexible cover plate is greater than that of the substrate layer farther from the inner bend of the flexible cover plate. This results in better surface hardness and impact resistance for the substrate layer closer to the inner bend of the flexible cover plate, while better bending performance for the substrate layer farther from the inner bend of the flexible cover plate. Thus, the flexible cover plate can balance bending performance, surface hardness, and impact resistance. Furthermore, when a flexible cover plate is used in a display device, the substrate layer with better bending performance can be located on the outer bend side, improving the bending performance of the display device, while the substrate layer with higher surface hardness and better impact resistance can be located on the inner bend side, improving the surface hardness and impact resistance of the display device. This allows the display device to balance bending performance, surface hardness, and impact resistance.

[0047] In one embodiment, the degree of polymerization of the substrate layer material near the inner bend of the flexible cover plate is greater than that of the substrate layer material away from the inner bend of the flexible cover plate. By making the degree of polymerization of the substrate layer material near the inner bend of the flexible cover plate greater than that of the substrate layer material away from the inner bend of the flexible cover plate, the elastic modulus of the substrate layer on the inner bend of the flexible cover plate is greater than that of the substrate layer away from the inner bend of the flexible cover plate. This results in better surface hardness and impact resistance of the substrate layer near the inner bend of the flexible cover plate, and better bending performance of the substrate layer away from the inner bend of the flexible cover plate. Thus, the flexible cover plate can balance bending performance, surface hardness, and impact resistance.

[0048] In one embodiment, such as Figure 2 As shown, in two adjacent substrate layers, the substrate layer closer to the inner bend of the flexible cover plate (e.g., the first substrate layer 11) is in direct contact with the substrate layer farther from the inner bend of the flexible cover plate (e.g., the second substrate layer 11). By making the substrate layer closer to the inner bend of the flexible cover plate in direct contact with the substrate layer farther from the inner bend of the flexible cover plate, the thickness of the flexible cover plate is reduced, resulting in better bending performance of the flexible cover plate. Furthermore, the substrate layer closer to the inner bend of the flexible cover plate also exhibits better surface hardness and impact resistance, thus allowing the flexible cover plate to balance bending performance, surface hardness, and impact resistance.

[0049] In one embodiment, such as Figure 2 As shown, when the flexible cover plate is bent inward, the flexible cover plate 1 further includes a hardening layer 13, which is disposed on the substrate layer near the inner side of the bend of the flexible cover plate 1 (e.g., in...). Figure 2 The first substrate layer 11) is located near the inner side of the bend of the flexible cover plate 1, and the elastic modulus of the hardened layer 13 is greater than that of the substrate layer near the inner side of the bend of the flexible cover plate. By including the hardened layer in the flexible cover plate, and making the elastic modulus of the hardened layer greater than that of the substrate layer near the inner side of the bend of the flexible cover plate, the surface hardness and impact resistance of the flexible cover plate are further improved. Furthermore, by placing the hardened layer on the side of the substrate layer near the inner side of the bend of the flexible cover plate, when the flexible cover plate is folded inward, the substrate layer located on the outer side of the bend has better bending performance, preventing the flexible cover plate from breaking during bending, while the substrate layer and hardened layer located on the inner side of the bend have better surface hardness and impact resistance, preventing damage to the flexible cover plate when subjected to impact, thus balancing the bending performance, surface hardness, and impact resistance of the flexible cover plate.

[0050] Specifically, such as Figure 2 As shown, the hardening layer 13 is disposed on the side of the first substrate layer 11 away from the second substrate layer 12, and the elastic modulus of the hardening layer 13 is greater than that of the first substrate layer 11. Specifically, for inward-folding flexible covers, i.e., flexible covers that bend from the edge of the flexible cover towards the middle area of ​​the flexible cover, or flexible covers that bend from the light-incident surface to the light-outcident surface of the flexible cover, the hardening layer can be disposed on the inner side of the bend of the flexible cover. This improves the surface hardness and impact resistance of the flexible cover by the hardening layer and the substrate layer near the inner side of the bend, while the substrate layer away from the inner side of the bend has better bending performance. This avoids the problem of breakage caused by the poor bending performance of the substrate layer located on the outer side of the bend, thus balancing the bending performance, surface hardness, and impact resistance of the flexible cover.

[0051] In one embodiment, such as Figure 1 As shown, when the flexible cover plate is bent outwards, the flexible cover plate 1 further includes a hardening layer 13, which is disposed on the substrate layer (e.g., away from the inner side of the bend of the flexible cover plate 1) Figure 1 The second substrate layer 12) is located away from the inner side of the bend of the flexible cover plate 1, and the elastic modulus of the hardened layer 13 is greater than that of the substrate layer (e.g., the one closer to the inner side of the bend of the flexible cover plate 1). Figure 1 The elastic modulus of the first substrate layer 11) in the flexible cover plate is increased. By including a hardening layer in the flexible cover plate, the elastic modulus of the hardening layer is made greater than that of the substrate layer near the inner side of the bend of the flexible cover plate, thereby further improving the surface hardness and impact resistance of the flexible cover plate. Furthermore, by placing the hardening layer on the side of the substrate layer away from the inner side of the bend of the flexible cover plate, when the flexible cover plate is folded outward, the bending performance of the substrate layer on the outer side of the bend is better, preventing the flexible cover plate from breaking during bending. The surface hardness and impact resistance of the hardening layer on the outer side of the bend are better, preventing the flexible cover plate from being damaged by impact. The surface hardness and impact resistance of the substrate layer on the inner side of the bend are also better, preventing the flexible cover plate from being damaged by impact. This balances the bending performance, surface hardness, and impact resistance of the flexible cover plate.

[0052] Specifically, such as Figure 1 As shown, the hardening layer 13 is disposed on the side of the second substrate layer 12 away from the first substrate layer 11, and the elastic modulus of the hardening layer 13 is greater than that of the first substrate layer 11. Specifically, for outward-folding flexible covers, i.e., flexible covers that bend from the middle region of the flexible cover towards the edge of the flexible cover, or flexible covers that bend from the light-emitting surface of the flexible cover to the light-receiving surface, the hardening layer can be disposed on the outside of the bend of the flexible cover. This allows the hardening layer to improve the surface hardness and impact resistance of the flexible cover. The substrate layer located on the outside of the bend has better bending performance, avoiding the problem of breakage caused by the poor bending performance of the substrate layer located on the outside of the bend. Furthermore, the substrate layer located on the inside of the bend has better surface hardness and impact resistance, further improving the surface hardness and impact resistance of the flexible cover, preventing damage to the flexible cover when subjected to impact, thus balancing the bending performance, surface hardness, and impact resistance of the flexible cover.

[0053] Specifically, the thickness of the hardened layer ranges from 3 micrometers to 20 micrometers. This range avoids the problem of low surface hardness and poor scratch resistance due to an insufficiently thin hardened layer, while also preventing the problem of poor bending performance due to an excessively thick hardened layer. The hardened layer thus balances bending performance, surface hardness, and scratch resistance.

[0054] Specifically, the materials for the hardened layer include polysiloxane-based materials, acrylic-based materials, or mixtures of both.

[0055] To address the issue that a significant performance difference between the first and second substrate layers can lead to stress abrupt changes and membrane failure, one embodiment proposes an incremental approach. When the flexible cover plate is bent, the elastic modulus of the multiple substrate layers increases progressively along the direction from the outer side of the bend to the inner side of the bend. By increasing the elastic modulus of the multiple substrate layers along this direction, the variation in elastic modulus between adjacent substrate layers can be minimized, thus preventing stress abrupt changes that could cause membrane failure.

[0056] In one embodiment, such as Figure 3 As shown, the flexible cover plate 1 further includes a third substrate layer 14. The material of the third substrate layer 14 is the same as that of the second substrate layer 12. The third substrate layer 14 is disposed on the side of the second substrate layer 12 away from the first substrate layer 11, and the elastic modulus of the third substrate layer 14 is less than that of the second substrate layer 12. By providing a third substrate layer in the flexible cover plate, making the material of the third substrate layer the same as that of the second substrate layer, disposing of the third substrate layer on the side of the second substrate layer away from the first substrate layer, and having an elastic modulus less than that of the second substrate layer, the elastic modulus gradually decreases from the first substrate layer to the third substrate layer. This results in a smaller difference in elastic modulus between adjacent substrate layers, preventing stress abrupt changes during bending of the flexible cover plate that could cause film layer breakage and failure, and improving the stability of the flexible cover plate.

[0057] Specifically, by making the elastic modulus of the third substrate layer smaller than that of the second substrate layer, the difference in elastic modulus between adjacent substrate layers can be minimized when setting up a flexible cover plate. This results in a smaller performance difference between adjacent substrate layers. Taking the third substrate layer as an example where the third substrate layer is located on the outside of the bend, the first substrate layer has the highest surface hardness and the best impact resistance, while the third substrate layer has the best bending performance. The surface hardness of the second substrate layer is lower than that of the first substrate layer but higher than that of the first substrate layer. The impact resistance of the second substrate layer is lower than that of the first substrate layer but better than that of the third substrate layer. The bending performance of the second substrate layer is lower than that of the third substrate layer but better than that of the first substrate layer. This results in a smaller performance difference between adjacent substrate layers, but the performance of the substrate layers located on the outside and inside of the bend differs, allowing the flexible cover plate to balance bending performance, surface hardness, and impact resistance.

[0058] Specifically, Figure 3 The example described is that the third substrate layer 14 is disposed on the side of the second substrate layer 12 away from the hardened layer 13. However, the embodiments of this application are not limited to this. For example, the third substrate layer may be disposed between the second substrate layer and the hardened layer.

[0059] Specifically, the above embodiments are illustrated using a flexible cover plate comprising a first substrate layer, a second substrate layer, and a third substrate layer as an example. However, the embodiments of this application are not limited to this, and for example, a fourth substrate layer, a fifth substrate layer, etc., may also be provided.

[0060] To address the issue that excessive performance differences between adjacent substrate layers can lead to stress abrupt changes and membrane failure, one embodiment specifies that the difference in elastic modulus between adjacent substrate layers is less than or equal to 100 MPa. Ensuring this difference in elastic modulus between adjacent substrate layers is less than or equal to 100 MPa prevents excessive elastic modulus differences between adjacent membrane layers from causing stress abrupt changes during bending, thus improving the stability of the flexible cover plate.

[0061] Specifically, taking a substrate layer including a first substrate layer and a second substrate layer as an example, when the first substrate layer and the second substrate layer are bonded together, the difference between the elastic modulus of the first substrate layer and the elastic modulus of the second substrate layer can be less than or equal to 100 megapascals.

[0062] Specifically, for example, if the elastic modulus of the first substrate layer is 4 gigapascals, then the elastic modulus of the second substrate layer can be 3.9 gigapascals.

[0063] Specifically, the elastic modulus of the substrate layer on the inner side of the bend away from the flexible cover plate is greater than or equal to 4 GPa. By ensuring that the elastic modulus of the substrate layer on the inner side of the bend away from the flexible cover plate is greater than or equal to 4 GPa, each substrate layer in the flexible cover plate can meet the surface hardness and impact resistance requirements during the use of the flexible cover plate, avoiding low surface hardness and poor impact resistance. In one embodiment, the material of the substrate layer includes polyethylene terephthalate.

[0064] In one embodiment, the thickness of the substrate layer is greater than or equal to 10 micrometers. This thickness gives the substrate layer a certain surface hardness and impact resistance, preventing the substrate layer from being easily damaged and failing due to insufficient thickness.

[0065] Specifically, the thickness of the first substrate layer is greater than or equal to 10 micrometers. This thickness ensures that the first substrate layer has a certain surface hardness and impact resistance, preventing the first substrate layer from being easily damaged and failing due to insufficient thickness.

[0066] Specifically, the thickness of the second substrate layer is greater than or equal to 10 micrometers. This thickness ensures that the second substrate layer has a certain surface hardness and impact resistance, preventing the second substrate layer from being easily damaged and failing due to insufficient thickness.

[0067] Specifically, the above embodiments describe the thickness of the first substrate layer and the second substrate layer, but the embodiments of this application are not limited thereto. For example, when the flexible cover plate includes a third substrate layer, the thickness of the third substrate layer can be greater than or equal to 10 micrometers.

[0068] In one embodiment, the thickness of the flexible cover plate ranges from 20 micrometers to 200 micrometers. This range avoids the problem of excessive thickness leading to poor bending performance, and also avoids the problem of insufficient thickness leading to poor surface hardness and impact resistance. This balances the bending performance, surface hardness, and impact resistance of the flexible cover plate.

[0069] Meanwhile, embodiments of this application provide a method for preparing a flexible cover plate, such as... Figure 4 As shown, the method for preparing the flexible cover plate is used to prepare a flexible cover plate as described in any of the above embodiments. The method for preparing the flexible cover plate includes:

[0070] S1, polyethylene terephthalate particles of different molecular weights are put into different feed ports, so that the polyethylene terephthalate particles of different molecular weights melt and flow from different channels into the same casting plate.

[0071] S2, stretching and cooling the molten polyethylene terephthalate to obtain a flexible cover plate.

[0072] This application provides a method for preparing a flexible cover plate. The flexible cover plate prepared by this method includes at least two substrate layers. The elastic modulus of the substrate layer closer to the inner bending side of the flexible cover plate is greater than that of the substrate layer farther from the inner bending side of the flexible cover plate. Therefore, the bending performance of the substrate layer farther from the inner bending side of the flexible cover plate is better than that of the substrate layer closer to the inner bending side of the flexible cover plate. The surface hardness and impact resistance of the substrate layer closer to the inner bending side of the flexible cover plate are also better than those of the substrate layer farther from the inner bending side of the flexible cover plate. When the flexible cover plate is bonded to a display panel, the substrate layer with a relatively lower elastic modulus in the flexible cover plate can be placed on the outer bending side of the display device to improve the bending performance of the display device and prevent the display device from failing due to excessive bending stress. The substrate layer with a relatively higher elastic modulus can be placed on the inner bending side of the display device to improve the surface hardness and impact resistance of the display device, thereby balancing the bending performance and surface hardness of the display device.

[0073] Specifically, such as Figure 5 As shown, with Figure 5Taking the flexible cover plate preparation apparatus shown as an example, the apparatus includes a first feed inlet 211, a second feed inlet 212, a first flow channel 221, a second flow channel 222, a casting plate 23, and a stretching unit 24. When preparing the flexible cover plate, polyethylene terephthalate (PET) particles with a molecular weight range of 24,000 to 26,000 can be added to the first feed inlet 211 for melting, and polyethylene terephthalate (PET) particles with a molecular weight range of 22,000 to 24,000 can be added to… The second feed inlet 212 is used for melting, so that polyethylene terephthalate particles with a molecular weight range of 22,000 to 24,000 flow out from the first flow channel 221 after melting, and polyethylene terephthalate particles with a molecular weight range of 22,000 to 24,000 flow out from the second flow channel 222 after melting. After polyethylene terephthalate with different molecular weights are combined together, the molten polyethylene terephthalate is stretched by the stretching unit 24 to obtain the first substrate layer and the second substrate layer.

[0074] Specifically, when stretching molten polyethylene terephthalate, both transverse and longitudinal stretching can be performed to form a polyethylene terephthalate film.

[0075] Specifically, to obtain polyethylene terephthalate (PET) particles of different molecular weights, terephthalic acid and ethylene glycol can be subjected to a polycondensation reaction, followed by granulation to produce PET particles. During the preparation process, the degree of polymerization is controlled by adjusting the ratio of reactants, reaction temperature, reaction time, and vacuum level to obtain PET particles of different molecular weights. Furthermore, the molecular weight of the PET particles can be controlled within the range of 20,000 to 30,000.

[0076] Specifically, a polysiloxane-based material can be coated onto the first substrate layer to form a hardened layer, further improving the bending performance, surface hardness, and scratch resistance of the flexible cover plate.

[0077] In one embodiment, the average molecular weight of the substrate layer near the inner side of the bend of the flexible cover plate is greater than the average molecular weight of the substrate layer away from the inner side of the bend of the flexible cover plate. By making the average molecular weight of the substrate layer near the inner side of the bend of the flexible cover plate greater than the average molecular weight of the substrate layer away from the inner side of the bend of the flexible cover plate, the elastic modulus of the substrate layer near the inner side of the bend of the flexible cover plate is greater than the elastic modulus of the substrate layer away from the inner side of the bend of the flexible cover plate. Therefore, when the flexible cover plate is bonded to the display panel, the substrate layer with a relatively lower elastic modulus in the flexible cover plate can be placed on the outer side of the bend of the display device, improving the bending performance of the display device and preventing the display device from failing due to excessive bending stress. Conversely, the substrate layer with a relatively higher elastic modulus can be placed on the inner side of the bend of the display device, improving the surface hardness and impact resistance of the display device, thus balancing the bending performance and surface hardness of the display device.

[0078] Specifically, the average molecular weight of the first substrate layer is greater than the average molecular weight of the second substrate layer.

[0079] In one embodiment, the molecular weight of the first substrate layer ranges from 24,000 to 30,000. By setting the molecular weight of the first substrate layer to between 24,000 and 30,000, the first substrate layer can meet the surface hardness and impact resistance requirements during the use of the flexible cover, thus avoiding situations where the flexible cover has low surface hardness and poor impact resistance.

[0080] Specifically, the molecular weight of the first substrate layer ranges from 24,000 to 30,000, so the average molecular weight of the first substrate layer can also range from 24,000 to 30,000, so that the first substrate layer can meet the surface hardness and impact resistance requirements during the use of the flexible cover plate, and avoid the flexible cover plate having low surface hardness and poor impact resistance.

[0081] Specifically, the molecular weight range of the first substrate layer can be 24,000 to 26,000, and the average molecular weight range of the first substrate layer can also be 24,000 to 26,000, so that the first substrate layer can meet the surface hardness and impact resistance requirements during the use of the flexible cover plate, and avoid the flexible cover plate having low surface hardness and poor impact resistance.

[0082] In one embodiment, the molecular weight of the second substrate layer is in the range of 22,000 to 24,000. This range provides good bending performance of the second substrate layer and minimizes the difference in molecular weight between the second substrate layer and the first substrate layer. This avoids the problem of excessive difference in elastic modulus between adjacent film layers causing stress abrupt changes when the flexible cover plate is bent, which could lead to film layer breakage and failure.

[0083] Specifically, the molecular weight range of the second substrate layer is 22,000 to 24,000, so the average molecular weight range of the second substrate layer can also be 22,000 to 24,000, which makes the second substrate layer have good bending performance, as well as certain surface hardness and impact resistance, thereby improving the flexibility of the flexible cover plate.

[0084] Specifically, the above embodiments describe the molecular weight of the first substrate layer and the second substrate layer, but the embodiments of this application are not limited thereto. For example, when a third substrate layer is present, the molecular weight of the third substrate layer can be in the range of 20,000 to 24,000.

[0085] In one embodiment, the difference between the average molecular weight of the first substrate layer and the average molecular weight of the second substrate layer ranges from 1 to 2000. By making the difference between the average molecular weight of the first substrate layer and the average molecular weight of the second substrate layer range from 1 to 2000, the performance difference between the first substrate layer and the second substrate layer is small, avoiding excessive difference in elastic modulus between adjacent film layers, which could lead to stress abrupt changes during bending and cause film layer breakage failure, thereby improving the stability of the flexible cover plate.

[0086] Specifically, for example, if the average molecular weight of the first substrate layer is 25,000, then the average molecular weight of the second substrate layer is 23,000. This makes the difference in elastic modulus between adjacent substrate layers smaller, avoiding excessive difference in elastic modulus between adjacent substrate layers that could cause stress abrupt changes during bending, leading to film layer breakage and failure, and improving the stability of the flexible cover plate.

[0087] Meanwhile, this application provides a display device that includes a flexible cover plate as described in any of the above embodiments.

[0088] At the same time, such as Figure 6 , Figure 7 As shown, this application embodiment provides a display device, the display device 10 including:

[0089] Display panel 31;

[0090] A flexible cover plate 1 is capable of bending along a bend line. The flexible cover plate 1 is disposed on one side of the display panel 31. The flexible cover plate 1 includes at least two substrate layers (e.g., a first substrate layer 11 and a second substrate layer 12). In two adjacent substrate layers, the elastic modulus of the substrate layer (e.g., the first substrate layer 11) closer to the inner side of the bend of the flexible cover plate is greater than the elastic modulus of the substrate layer (e.g., the second substrate layer 12) farther away from the inner side of the bend of the flexible cover plate. The repeating structural units of the corresponding materials of each substrate layer are the same.

[0091] An adhesive layer 32 is disposed between the display panel 31 and the flexible cover plate 1.

[0092] This application provides a display device including a display panel, a flexible cover plate, and an adhesive layer. The flexible cover plate includes at least two substrate layers. The elastic modulus of the substrate layer closer to the inner bending side of the flexible cover plate is greater than that of the substrate layer farther from the inner bending side of the flexible cover plate. Therefore, the bending performance of the substrate layer farther from the inner bending side of the flexible cover plate is better than that of the substrate layer closer to the inner bending side of the flexible cover plate. The surface hardness and impact resistance of the substrate layer closer to the inner bending side of the flexible cover plate are also better than those of the substrate layer farther from the inner bending side of the flexible cover plate. When the flexible cover plate is bonded to the display panel, the substrate layer with a relatively lower elastic modulus in the flexible cover plate can be placed on the outer bending side of the display device to improve the bending performance of the display device and prevent the display device from failing due to excessive bending stress. The substrate layer with a relatively higher elastic modulus can be placed on the inner bending side of the display device to improve the surface hardness and impact resistance of the display device, thereby balancing the bending performance and surface hardness of the display device.

[0093] In one embodiment, the bend line of the flexible cover plate is the same as the bend line of the display device.

[0094] In one embodiment, such as Figure 7 As shown, when the display device is bent inwards, the substrate layer (e.g., the second substrate layer 12) on the inner side of the bend away from the flexible cover plate 1 is disposed between the display panel and the substrate layer (e.g., the first substrate layer 11) on the inner side of the bend near the flexible cover plate 1. By disposing the substrate layer on the inner side of the bend away from the flexible cover plate between the display panel and the substrate layer on the inner side of the bend near the flexible cover plate, when the display device is bent inwards, the substrate layer with a lower elastic modulus is located on the outer side of the bend of the display device, improving the bending performance of the display device, while the substrate layer with a higher elastic modulus is disposed on the inner side of the bend of the display device, improving the surface hardness and impact resistance of the display device, thus balancing the bending performance, surface hardness, and impact resistance of the display device.

[0095] Specifically, such as Figure 6 , Figure 7 As shown, in an inward-folding display device or a display device bent inward, the display device bends from the display panel toward the flexible cover plate, resulting in greater stress on the outer side of the bend. Therefore, in this embodiment, a substrate layer with a lower elastic modulus is placed on the outer side of the bend, so that the bending performance of the film layer on the outer side of the bend is better, avoiding excessive bending stress that could cause the display device to fail. At the same time, the substrate layer on the inner side of the bend has better surface hardness and impact resistance, which can improve the surface hardness and impact resistance of the display device, thus balancing the bending performance, surface hardness, and impact resistance of the display device.

[0096] Specifically, such as Figure 7As shown, in order to further improve the surface hardness and impact resistance of the display device, a hardening layer 13 can also be provided on the side of the first substrate layer 11 away from the second substrate layer 12.

[0097] In one embodiment, such as Figure 9 As shown, when the display device is bent outwards, the substrate layer (e.g., the first substrate layer 11) near the inner side of the bend of the flexible cover plate 1 is disposed between the substrate layer (e.g., the second substrate layer 12) on the inner side of the bend of the display panel away from the flexible cover plate 1. By disposing the substrate layer near the inner side of the bend of the flexible cover plate between the display panel and the substrate layer away from the flexible cover plate, when the display device is bent outwards, the substrate layer with a lower elastic modulus is located on the outer side of the bend of the display device, improving the bending performance of the display device, while the substrate layer with a higher elastic modulus is disposed on the inner side of the bend of the display device, improving the surface hardness and impact resistance of the display device, thus balancing the bending performance, surface hardness, and impact resistance of the display device.

[0098] Specifically, such as Figure 8 , Figure 9 As shown, when describing an outward-folding display device or a display device bending outwards, the display device bends from the flexible cover plate toward the display panel, resulting in greater stress on the outer side of the bend. Therefore, in this embodiment, a substrate layer with a lower elastic modulus is placed on the outer side of the bend, so that the bending performance of the film layer on the outer side of the bend is better, avoiding excessive bending stress that could cause the display device to fail. At the same time, the substrate layer on the inner side of the bend has better surface hardness and impact resistance, which can improve the surface hardness and impact resistance of the display device, thus balancing the bending performance, surface hardness, and impact resistance of the display device.

[0099] The above embodiments are illustrated using examples of an inward-folding or outward-folding display device, or a display device bending inward or outward. However, the embodiments of this application are not limited to this. For example, the display device can be bent inward and outward during use. In the embodiments of this application, by setting multiple substrate layers, such as a first substrate layer and a second substrate layer, the first substrate layer improves the surface hardness and impact resistance of the display device, and the second substrate layer improves the bending performance of the display device. This ensures that the display device will not fail when bent inward or outward, thus balancing the bending performance, surface hardness, and impact resistance of the display device.

[0100] Specifically, such as Figure 7 As shown, the display panel includes a substrate 41, a driving circuit layer, a light-emitting functional layer and an encapsulation layer 44 arranged sequentially.

[0101] Specifically, such as Figure 7As shown, the driving circuit layer includes an active layer 421, a gate insulating layer 422, a gate layer 423, an interlayer insulating layer 424, a source-drain layer 425, and a planarization layer 426 arranged sequentially.

[0102] Specifically, such as Figure 7 As shown, the light-emitting functional layer includes a pixel electrode layer 431, a pixel definition layer 432, a light-emitting material layer 433, and a common electrode layer 434 arranged sequentially.

[0103] Specifically, the above embodiments use the example of the gate being disposed above the active layer to illustrate the driving circuit layer, but the embodiments of this application are not limited to this. For example, the gate is disposed below the active layer, and the driving circuit layer may include a first metal layer and a second metal layer. The first metal layer includes the gate and the second metal layer includes the capacitor plate. In another example, the driving circuit layer may include at least one of low-temperature polycrystalline silicon thin-film transistors, oxide thin-film transistors, and low-temperature polycrystalline oxide thin-film transistors.

[0104] As can be seen from the above embodiments:

[0105] This application provides a flexible cover plate, its preparation method, and a display device. The flexible cover plate can be bent along a bending line. The flexible cover plate includes at least two substrate layers. In two adjacent substrate layers, the elastic modulus of the substrate layer closer to the inner side of the bend is greater than that of the substrate layer farther from the inner side of the bend, and the repeating structural units of the corresponding materials of each substrate layer are the same. This application incorporates at least two substrate layers into a flexible cover plate, with the elastic modulus of the substrate layer closer to the inner bend of the flexible cover plate being greater than that of the substrate layer farther from the inner bend. This results in superior bending performance for the substrate layer farther from the inner bend, and also superior surface hardness and impact resistance for the substrate layer closer to the inner bend. Therefore, when the flexible cover plate is bonded to the display panel, the substrate layer with a relatively lower elastic modulus can be positioned on the outer bend side of the display device, improving its bending performance and preventing failure due to excessive bending stress. Conversely, the substrate layer with a relatively higher elastic modulus can be positioned on the inner bend side of the display device, improving its surface hardness and impact resistance. This approach balances both the bending performance and surface hardness of the display device.

[0106] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0107] The above provides a detailed description of a flexible cover plate, its preparation method, and a display device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A flexible cover plate, characterized in that, The flexible cover plate is capable of bending along a bend line. The flexible cover plate includes at least two substrate layers. In two adjacent substrate layers, the elastic modulus of the substrate layer closer to the inner side of the bend is greater than that of the substrate layer farther from the inner side of the bend, and the repeating structural units of the corresponding materials of each substrate layer are the same. The degree of polymerization of the material corresponding to the substrate layer closer to the inner side of the bend is greater than that of the material corresponding to the substrate layer farther from the inner side of the bend.

2. The flexible cover plate as described in claim 1, characterized in that, In two adjacent substrate layers, the substrate layer closer to the inner side of the bend of the flexible cover plate is in direct contact with the substrate layer further away from the inner side of the bend of the flexible cover plate.

3. The flexible cover plate as described in claim 1, characterized in that, When the flexible cover plate is bent inward, the flexible cover plate further includes a hardening layer. The hardening layer is disposed on the side of the substrate layer near the inside of the bend of the flexible cover plate, and the elastic modulus of the hardening layer is greater than the elastic modulus of the substrate layer near the inside of the bend of the flexible cover plate.

4. The flexible cover plate as described in claim 1, characterized in that, When the flexible cover plate is bent outward, the flexible cover plate further includes a hardening layer. The hardening layer is disposed on the side of the substrate layer away from the inner side of the bend of the flexible cover plate, and the elastic modulus of the hardening layer is greater than the elastic modulus of the substrate layer near the inner side of the bend of the flexible cover plate.

5. The flexible cover plate as described in claim 1, characterized in that, When the flexible cover plate is in a bent state, the elastic modulus of the multiple substrate layers increases in the direction from the outer side of the bend to the inner side of the bend.

6. The flexible cover plate as described in claim 5, characterized in that, The difference in elastic modulus between adjacent substrate layers is less than or equal to 100 megapascals.

7. The flexible cover plate as described in claim 1, characterized in that, The elastic modulus of the substrate layer on the inner side of the bend away from the flexible cover plate is greater than or equal to 4 gigapascals.

8. The flexible cover plate as described in claim 1, characterized in that, The thickness of the substrate layer is greater than or equal to 10 micrometers.

9. The flexible cover plate as described in claim 1, characterized in that, The thickness of the flexible cover plate ranges from 20 micrometers to 200 micrometers.

10. A method for preparing a flexible cover plate, characterized in that, The method for preparing the flexible cover plate as described in any one of claims 1 to 9 includes: Polyethylene terephthalate particles of different molecular weights are placed into different feed ports, so that the polyethylene terephthalate particles of different molecular weights melt and flow from different channels into the same casting plate. A flexible cover plate is obtained by stretching and cooling the molten polyethylene terephthalate.

11. The method for preparing the flexible cover plate as described in claim 10, characterized in that, The average molecular weight of the substrate layer on the inner side of the bend closer to the flexible cover plate is greater than the average molecular weight of the substrate layer on the inner side of the bend farther from the flexible cover plate.

12. A display device, characterized in that, include: Display panel; A flexible cover plate, which can be bent along a bend line, is disposed on one side of the display panel. The flexible cover plate includes at least two substrate layers. In two adjacent substrate layers, the elastic modulus of the substrate layer closer to the inner bend of the flexible cover plate is greater than that of the substrate layer farther from the inner bend of the flexible cover plate, and the repeating structural units of the corresponding materials of each substrate layer are the same; the degree of polymerization of the material corresponding to the substrate layer closer to the inner bend of the flexible cover plate is greater than that of the material corresponding to the substrate layer farther from the inner bend of the flexible cover plate. An adhesive layer is disposed between the display panel and the flexible cover plate.

13. The display device as claimed in claim 12, characterized in that, When the bending direction of the display device is inward, the substrate layer on the inner side of the bend away from the flexible cover plate is disposed between the display panel and the substrate layer on the inner side of the bend near the flexible cover plate.

14. The display device as claimed in claim 12, characterized in that, When the bending direction of the display device is outward, the substrate layer near the inner side of the bend of the flexible cover plate is disposed between the display panel and the substrate layer away from the inner side of the bend of the flexible cover plate.

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