Protective film and electronic device

Abstract

The invention provides a protective film of a flexible screen. The protective film comprises a transparent hardened layer, a transparent polymer resin layer and a transparent adhesive layer which are stacked in sequence, wherein the transparent adhesive layer is used for being bonded with a light-emitting surface of the flexible screen. According to the invention, the elongation at break of the transparent hardened layer, the modulus of the transparent polymer resin layer, the plane angle of the transparent polymer resin layer, the modulus of the transparent adhesive layer in an environment of 40-80 DEG C and the shape recovery rate of the transparent adhesive layer can be designed; the problem that the protective film is easy to peel off from the flexible screen is solved through at least one of parameters such as the peeling force of the transparent adhesive layer. The invention further provides a flexible screen module comprising the protective film and a flexible screen, and the protective film is bonded with the light emitting surface of the flexible screen. The invention further provides an electronic device comprising the flexible screen module.

Description

[0001] This application is a divisional application. The application number of the original application is 202010605246.7, and the original application date is June 29, 2020. The entire content of the original application is incorporated into this application by reference. Technical Field

[0002] The present application relates to the technical field of terminal products, and in particular to a protective film and an electronic device. Background Art

[0003] Foldable phones use a bendable flexible screen, which is typically covered with a protective film on the front. This film protects the screen and, due to its flexibility and bendability, adapts well to the bending process of the flexible screen. However, conventional flexible screens can easily peel off the protective film after repeated bending, affecting their reliability. Summary of the Invention

[0004] The present application provides a protective film for a flexible screen, a flexible screen module and an electronic device, which can solve the problem that the protective film is easily peeled off from the flexible screen.

[0005] In a first aspect, the present application provides a protective film for a flexible screen, the flexible screen having a light-emitting surface. The protective film comprises a transparent hardened layer, a transparent polymer resin layer, and a transparent adhesive layer laminated in sequence, wherein the transparent adhesive layer is used to bond to the light-emitting surface. The transparent adhesive layer has a modulus of 15 kPa to 25 kPa in an environment of 40°C to 80°C; and / or a shape recovery rate of greater than or equal to 90%; and / or a peel force of (200 gf to 1500 gf) / 25 mm.

[0006] In the present application, the light-emitting surface is the surface from which the flexible screen emits light, that is, the surface from which the flexible screen displays the image. The transparent hardened layer, as the outer layer in the protective film that can be touched by the user, has a high hardness (for example, the pencil hardness of the transparent hardened layer under a force of 1 kgf is ≥ 1H), which can provide a relatively hard touch and is also convenient for protecting other layers in the protective film. The transparent hardened layer is transparent, which allows the light emitted by the flexible screen to pass through. The thickness of the transparent hardened layer can be 1 μm-8 μm and can be formed by a coating process. The transparent hardened layer can contain wear-resistant inorganic particles and / or anti-fingerprint agents. The former can increase the wear resistance of the transparent hardened layer, and the latter can enhance the anti-fingerprint trace performance of the transparent hardened layer. The transparent polymer resin layer is made of a transparent polymer resin material. The transparent polymer resin layer is transparent and can allow the light emitted by the flexible screen to pass through. The transparent polymer resin layer is the main layer in the protective film, and the transparent polymer resin layer mainly plays a structural support role in the protective film. The thickness of the transparent polymer resin layer can be 25 μm-100 μm. The transparent adhesive layer is used to bond to the light-emitting surface of the flexible screen, thereby ensuring that the entire protective film is adhered to the flexible screen. The transparent adhesive layer is transparent, allowing light emitted by the flexible screen to pass through. The thickness of the transparent adhesive layer can be 15μm-50μm.

[0007] In this application, at least one of the following designs can be made for the transparent adhesive layer to reduce the risk of the protective film and the flexible screen peeling off:

[0008] 1. The modulus of the transparent adhesive layer in a high temperature environment (for example, in an environment of 40°C-80°C) is 15Kpa-25Kpa. The modulus of this transparent adhesive layer is low, and the transparent adhesive layer is easy to deform. When bent, the internal stress of the transparent adhesive layer is small, and it is not easy to peel off from the light-emitting surface. The transparent adhesive layer is limited to have the above modulus value in this high temperature environment in order to adapt to the actual use environment of the transparent adhesive layer to ensure that the transparent adhesive layer can be reliably combined with the light-emitting surface during use. Therefore, the protective film in Design 1 can reduce or even avoid the risk of peeling off from the flexible screen by using this transparent adhesive layer with a lower modulus, thereby improving the reliability of the flexible screen.

[0009] 2. The shape recovery rate of the transparent adhesive layer is maintained at a level of ≥90%. After multiple bending processes, such a transparent adhesive layer has less permanent deformation and can be very reliably attached to the light-emitting surface. Therefore, it can reduce or even avoid the risk of peeling between the protective film and the flexible screen, thereby improving the reliability of the flexible screen. Among them, the shape recovery rate refers to the ratio of the deformation amount that can be recovered after the load is removed when the material is deformed under the action of a load to the total deformation amount. The shape recovery rate can be measured in the following way: at room temperature, a load of 10Kpa (which can be a torsional load) is continuously applied to the material sample (which can be processed into a strip or column) for 1 hour, and then the load is removed. When the material sample stops recovering the deformation, the shape recovery rate is measured.

[0010] 3. The peeling force of the transparent adhesive layer is (200gf-1500gf) / 25mm. The peeling force of this transparent adhesive layer is sufficient to ensure that it is always combined with the light-emitting surface during repeated bending. Therefore, it can reduce or even avoid the risk of peeling between the protective film and the flexible screen, and improve the reliability of the flexible screen. Among them, the peeling force can represent the size of the bonding force between the transparent adhesive layer and the light-emitting surface. The peeling force can be measured, for example, in the following way: under the test environment, a sample of the transparent adhesive layer is pasted on the target surface, the sample is lifted and folded 180 degrees, and then the sample is pulled from the target surface at a certain speed (for example, 300mm / min), and the pulling force of the pulling sample is measured during this process. When the peeling distance reaches the set value, the maximum tensile force measured is the peeling force of the sample. The unit of peeling force can be gf / 25mm, which means the peeling force measured when the width of the sample is 25mm.

[0011] In one implementation, the modulus of the transparent polymer resin layer is 2 GPa to 15 GPa; and / or the elongation at break of the transparent polymer resin layer is greater than or equal to 15%; and / or the plane angle of the transparent polymer resin layer is greater than or equal to 150°. The elongation at break represents the ratio of the elongated length of the material when it is stretched to the length before stretching. After multiple bends, the transparent polymer resin layer forms a structure with straight sections at both ends and a bent section between the two straight sections. The angle between the two straight sections in this structure is called the plane angle. The plane angle can indicate the deformation recovery ability of the transparent polymer resin layer.

[0012] In this implementation, at least one of the three parameters of the transparent polymer resin layer, namely the modulus, elongation at break, and plane angle, can be reasonably designed to reduce the risk of peeling between the protective film and the flexible screen. Specifically, the modulus of the transparent polymer resin layer is 2GPa-15GPa, making the transparent polymer resin layer easier to bend, ensuring reliable bonding between the transparent adhesive layer and the light-emitting surface, and reducing the stress in the interface between the transparent adhesive layer and the light-emitting surface, which helps to reduce the risk of peeling between the protective film and the flexible screen and improve the reliability of the flexible screen. The elongation at break of the transparent polymer resin layer is greater than or equal to 15%, which makes the transparent polymer resin layer have good toughness and can well adapt to the reciprocating deformation during the bending process, thereby helping to reduce the risk of peeling between the protective film and the flexible screen and improve the reliability of the flexible screen. The plane angle of the transparent polymer resin layer is ≥150°, which makes the transparent polymer resin layer have strong deformation recovery ability and is not easy to warp after multiple bending, thereby helping to reduce the risk of peeling between the protective film and the flexible screen and improve the reliability of the flexible screen.

[0013] In one implementation, the transparent hardened layer has an elongation at break of greater than or equal to 2%. A transparent hardened layer with this elongation at break has good toughness and can adapt well to the reciprocating deformation during bending, thereby reducing the risk of separation between the protective film and the flexible screen and improving the reliability of the flexible screen.

[0014] In the second aspect, the present application provides a protective film for a flexible screen, the flexible screen having a light-emitting surface, the protective film comprising a transparent hardened layer, a transparent polymer resin layer and a transparent adhesive layer stacked in sequence, wherein the transparent adhesive layer is used to bond to the light-emitting surface; the modulus of the transparent polymer resin layer is 2Gpa-4Gpa; and / or the elongation at break of the transparent polymer resin layer is greater than or equal to 25%; and / or the plane angle of the transparent polymer resin layer is greater than or equal to 150°.

[0015] In the present application, the light-emitting surface is the surface from which the flexible screen emits light, that is, the surface from which the flexible screen displays the image. The transparent hardened layer, as the outer layer in the protective film that can be touched by the user, has a high hardness (for example, the pencil hardness of the transparent hardened layer under a force of 1 kgf is ≥ 1H), which can provide a relatively hard touch and is also convenient for protecting other layers in the protective film. The transparent hardened layer is transparent, which allows the light emitted by the flexible screen to pass through. The thickness of the transparent hardened layer can be 1 μm-8 μm and can be formed by a coating process. The transparent hardened layer can contain wear-resistant inorganic particles and / or anti-fingerprint agents. The former can increase the wear resistance of the transparent hardened layer, and the latter can enhance the anti-fingerprint trace performance of the transparent hardened layer. The transparent polymer resin layer is made of a transparent polymer resin material. The transparent polymer resin layer is transparent and can allow the light emitted by the flexible screen to pass through. The transparent polymer resin layer is the main layer in the protective film, and the transparent polymer resin layer mainly plays a structural support role in the protective film. The thickness of the transparent polymer resin layer can be 25 μm-100 μm. The transparent adhesive layer is used to bond to the light-emitting surface of the flexible screen, thereby ensuring that the entire protective film is adhered to the flexible screen. The transparent adhesive layer is transparent, allowing light emitted by the flexible screen to pass through. The thickness of the transparent adhesive layer can be 15μm-50μm.

[0016] In this application, at least one of the following designs can be made for the transparent polymer resin layer to reduce the risk of peeling between the protective film and the flexible screen:

[0017] 1. The modulus of the transparent polymer resin layer is 2Gpa-4Gpa. The modulus of this transparent polymer resin layer is relatively low (the modulus of the conventional transparent polymer resin layer is relatively high, for example, it can reach 5.4Gpa). The transparent polymer resin layer is easy to bend, which can ensure the reliable bonding of the transparent adhesive layer and the light-emitting surface, so that the stress on the interface between the transparent adhesive layer and the light-emitting surface is relatively small, which is beneficial to reduce the risk of peeling between the protective film and the flexible screen and improve the reliability of the flexible screen.

[0018] 2. The elongation at break of the transparent polymer resin layer is greater than or equal to 25%. The transparent polymer resin layer with such an elongation at break has good toughness and can adapt well to the reciprocating deformation during the bending process, thereby reducing the risk of peeling between the protective film and the flexible screen and improving the reliability of the flexible screen.

[0019] 3. The plane angle of the transparent polymer resin layer is ≥150°, which makes the transparent polymer resin layer have strong deformation recovery ability and is not easy to warp after multiple bending, thereby reducing the risk of peeling between the protective film and the flexible screen and improving the reliability of the flexible screen.

[0020] In one implementation, the shape recovery rate of the transparent adhesive layer is greater than or equal to 80%; and / or, the peeling force of the transparent adhesive layer is (50gf-2000gf) / 25mm. The former design makes the transparent adhesive layer less permanently deformed after multiple bending processes, and can very reliably adhere to the light-emitting surface, thereby reducing or even avoiding the risk of peeling between the protective film and the flexible screen, and improving the reliability of the flexible screen. The latter design makes the peeling force of the transparent adhesive layer more sufficient, and can ensure that it is always combined with the light-emitting surface during multiple repeated bending processes, thereby reducing or even avoiding the risk of peeling between the protective film and the flexible screen, and improving the reliability of the flexible screen. In addition, the peeling force of the transparent adhesive layer in the latter design is also more appropriate, avoiding the difficulty of tearing the protective film from the flexible screen due to excessive peeling force, which causes difficulties in maintenance.

[0021] In one implementation, the transparent hardened layer has an elongation at break of greater than or equal to 2%. A transparent hardened layer with this elongation at break has good toughness and can adapt well to the reciprocating deformation during bending, thereby reducing the risk of separation between the protective film and the flexible screen and improving the reliability of the flexible screen.

[0022] In the third aspect, the present application provides a protective film for a flexible screen, the flexible screen having a light-emitting surface, and the protective film comprising a transparent hardened layer, a transparent polymer resin layer and a transparent adhesive layer stacked in sequence, wherein the transparent adhesive layer is used to bond to the light-emitting surface; the elongation at break of the transparent hardened layer is greater than or equal to 2.5%.

[0023] In the present application, the light-emitting surface is the surface from which the flexible screen emits light, that is, the surface from which the flexible screen displays the image. The transparent hardened layer, as the outer layer in the protective film that can be touched by the user, has a high hardness (for example, the pencil hardness of the transparent hardened layer under a force of 1 kgf is ≥ 1H), which can provide a relatively hard touch and is also convenient for protecting other layers in the protective film. The transparent hardened layer is transparent, which allows the light emitted by the flexible screen to pass through. The thickness of the transparent hardened layer can be 1 μm-8 μm and can be formed by a coating process. The transparent hardened layer can contain wear-resistant inorganic particles and / or anti-fingerprint agents. The former can increase the wear resistance of the transparent hardened layer, and the latter can enhance the anti-fingerprint trace performance of the transparent hardened layer. The transparent polymer resin layer is made of a transparent polymer resin material. The transparent polymer resin layer is transparent and can allow the light emitted by the flexible screen to pass through. The transparent polymer resin layer is the main layer in the protective film, and the transparent polymer resin layer mainly plays a structural support role in the protective film. The thickness of the transparent polymer resin layer can be 25 μm-100 μm. The transparent adhesive layer is used to bond to the light-emitting surface of the flexible screen, thereby ensuring that the entire protective film is adhered to the flexible screen. The transparent adhesive layer is transparent, allowing light emitted by the flexible screen to pass through. The thickness of the transparent adhesive layer can be 15μm-50μm.

[0024] In this application, the transparent hardened layer with such elongation at break has good toughness and can adapt well to the reciprocating deformation during the bending process, thereby helping to reduce the risk of peeling between the protective film and the flexible screen and improving the reliability of the flexible screen.

[0025] In one implementation, the shape recovery rate of the transparent adhesive layer is greater than or equal to 80%; and / or, the peeling force of the transparent adhesive layer is (50gf-2000gf) / 25mm. The former design makes the transparent adhesive layer less permanently deformed after multiple bending processes, and can very reliably adhere to the light-emitting surface, thereby reducing or even avoiding the risk of peeling between the protective film and the flexible screen, and improving the reliability of the flexible screen. The latter design makes the peeling force of the transparent adhesive layer more sufficient, and can ensure that it is always combined with the light-emitting surface during multiple repeated bending processes, thereby reducing or even avoiding the risk of peeling between the protective film and the flexible screen, and improving the reliability of the flexible screen. In addition, the peeling force of the transparent adhesive layer in the latter design is also more appropriate, avoiding the difficulty of tearing the protective film from the flexible screen due to excessive peeling force, which causes difficulties in maintenance.

[0026] In one implementation, the modulus of the transparent polymer resin layer is between 2 GPa and 15 GPa; and / or the elongation at break of the transparent polymer resin layer is greater than or equal to 15%; and / or the plane angle of the transparent polymer resin layer is greater than or equal to 150°. In this implementation, at least one of the three parameters of the transparent polymer resin layer, namely the modulus, elongation at break, and plane angle, can be rationally designed to reduce the risk of peeling between the protective film and the flexible screen. Specifically, the modulus of the transparent polymer resin layer is between 2 GPa and 15 GPa, making it easier to bend, ensuring a reliable bond between the transparent adhesive layer and the light-emitting surface, and minimizing stress within the interface between the transparent adhesive layer and the light-emitting surface. This helps reduce the risk of peeling between the protective film and the flexible screen, thereby improving the reliability of the flexible screen. The elongation at break of the transparent polymer resin layer is greater than or equal to 15%, making the transparent polymer resin layer more resilient and able to adapt well to the reciprocating deformation during bending, thereby reducing the risk of peeling between the protective film and the flexible screen and improving the reliability of the flexible screen. The plane angle of the transparent polymer resin layer is ≥150°, which makes the transparent polymer resin layer have strong deformation recovery ability and is not easy to warp after multiple bending, thereby reducing the risk of peeling between the protective film and the flexible screen and improving the reliability of the flexible screen.

[0027] In one implementation, the transparent adhesive layer meets at least one of the following conditions: the modulus of the transparent adhesive layer in an environment of 40°C-80°C is 15KPa-25KPa; the shape recovery rate of the transparent adhesive layer is greater than or equal to 90%; and the peel force of the transparent adhesive layer is (200gf-1500gf) / 25mm. Furthermore, the transparent polymer resin layer meets at least one of the following conditions: the modulus of the transparent polymer resin layer is 2GPa-4GPa; the elongation at break of the transparent polymer resin layer is greater than or equal to 25%; and the plane angle of the transparent polymer resin layer is greater than or equal to 150°. By simultaneously designing the transparent adhesive layer and the transparent polymer resin layer, the risk of peeling between the protective film and the flexible screen can be greatly reduced, thereby improving the reliability of the flexible screen. For example, after actual verification, the solution of this implementation method can ensure that the protective film and the flexible screen of a flexible screen module with a bending radius R of 1mm≤R≤5mm can still be reliably bonded after at least tens of thousands of bending tests, and the surface of the protective film is free of damage, whitening, cracks, and other abnormalities.

[0028] In one implementation, the material of the transparent hardened layer is acrylic polyurethane resin; and / or the material of the transparent polymer resin layer is polyester film or epoxy resin film; and / or the material of the transparent adhesive layer is acrylic polyurethane resin or silicone. The use of the above materials to manufacture the various layers of the protective film ensures that the performance of the protective film is reliable and mass-producible. Among them, the transparent polymer resin layer manufactured using polyester film has better thermal performance and better dimensional stability when heated or damp. The transparent polymer resin layer manufactured using epoxy resin film has better deformation recovery performance. For example, it can still remain flat after being bent 200,000 times.

[0029] In one implementation, the transmittance of light with a wavelength of 550nm through the protective film is greater than or equal to 88%. The transmittance represents the ratio of the amount of light transmitted through the material layer to the total amount of light irradiated on the surface of the material layer. The higher the transmittance of the material layer, the better the light transmittance of the material layer. Since the human eye is more sensitive to light with a wavelength of 550nm, the transmittance of light with a wavelength of 550nm through it can be considered as the key consideration for the protective film. When the transmittance of light with a wavelength of 550nm through the protective film is greater than or equal to 88%, it can ensure that the light transmittance of the protective film meets the display requirements of the flexible screen.

[0030] In one implementation, the transmittance of light with a wavelength of 550 nm through the transparent polymer resin layer is greater than or equal to 85%, and the transmittance of light with a wavelength of 550 nm through the transparent adhesive layer is greater than or equal to 90%. By setting the transmittances of the transparent polymer resin layer and the transparent adhesive layer within the above ranges, it is possible to ensure that the transparent polymer resin layer and the transparent adhesive layer have high light transmittance, thereby ensuring that the light transmittance of the protective film (the transmittance of the protective film is substantially equal to the transmittance of the transparent polymer resin layer multiplied by the transmittance of the transparent adhesive layer) meets the display requirements of the flexible screen.

[0031] In one implementation, the haze of the transparent hardened layer is less than or equal to 1%. The haze of the transparent hardened layer represents the ratio of the intensity of light scattered by the surface of the transparent hardened layer to the total intensity of light incident on the surface of the transparent hardened layer. The lower the haze of the transparent hardened layer, the weaker the scattering of the transparent hardened layer, and the better the gloss and transparency of the transparent hardened layer. By setting the haze of the transparent hardened layer to less than or equal to 1%, the gloss and transparency of the transparent hardened layer can be ensured to meet the requirements, thereby ensuring the display performance of the flexible screen.

[0032] In one implementation, the surface roughness of the transparent hardened layer is less than or equal to 1 μm. The surface roughness of the transparent hardened layer can affect the haze. By setting the surface roughness of the transparent hardened layer to the above range, the requirement that the haze of the transparent hardened layer is less than or equal to 1% can be met.

[0033] Fourthly, the present application provides a flexible screen module comprising a flexible screen and the protective film, wherein the flexible screen has a light-emitting surface, and the transparent adhesive layer of the protective film is bonded to the light-emitting surface. In the flexible screen module of the present application, the protective film and the flexible screen are not easily peeled off, and the reliability of the flexible screen is high.

[0034] In a fifth aspect, the present application provides an electronic device including the flexible screen module. Such electronic devices include, but are not limited to, foldable screen electronic devices, such as foldable screen mobile phones and foldable screen tablets. Such electronic devices may also be wearable devices with flexible bending capabilities, such as smart clothing and smart watches. The protective film of such electronic devices is not easily separated from the flexible screen, and the flexible screen has a high reliability, thereby enhancing the reliability of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a side view structural diagram of an electronic device according to the first embodiment;

[0036] Figure 2 is a side structural diagram of another electronic device according to the first embodiment;

[0037] Figure 3 yes Figure 1 or Figure 2 Schematic diagram of the exploded structure of the electronic equipment in;

[0038] Figure 4 yes Figure 1 A schematic side view of the structure of a flexible screen module in an electronic device;

[0039] Figure 5 yes Figure 2 A schematic side view of the structure of a flexible screen module in an electronic device;

[0040] Figure 6 yes Figure 3 Schematic diagram of the decomposed structure of the flexible screen module in the electronic device. DETAILED DESCRIPTION

[0041] An embodiment of the present application provides an electronic device, including but not limited to a foldable screen electronic device, such as a foldable screen mobile phone or a foldable screen tablet computer. The electronic device may also be a wearable device with flexible bending capabilities, such as smart clothing or a smartwatch. The electronic device includes a flexible screen module. The following description uses a foldable screen electronic device as an example.

[0042] Figure 1 The figure shows the side view structure of the folding screen electronic device 10 in the first embodiment of the first embodiment. Figure 2 The figure shows the side view structure of the folding screen electronic device 10 in the second embodiment of the first embodiment. Figure 3 It indicates Figure 1 or Figure 2 The exploded structure of the foldable screen electronic device 10. Figure 1-Figure 3 As shown, the folding screen electronic device 10 of the first embodiment may include a first shell 11, a hinge 12, a second shell 13 and a flexible screen module 14.

[0043] The hinge 12 is connected to the first housing 11 and the second housing 13 on opposite sides. The hinge 12 can be a mechanism composed of multiple components, capable of mechanical movement. This mechanical movement of the hinge 12 enables the first housing 11 and the second housing 13 to rotate relative to each other, allowing the first housing 11 to expand or close relative to the second housing 13, thereby enabling the foldable screen electronic device 10 to be unfolded or folded.

[0044] Both the first housing 11 and the second housing 13 may serve as exterior components of the foldable electronic device 10, i.e., components that are exposed and directly observable by the user. Alternatively, the foldable electronic device 10 may include a housing as an exterior component, and both the first housing 11 and the second housing 13 may serve as non-exterior components (e.g., a midframe) mounted within the housing. The first housing 11 and the second housing 13 are used to mount the flexible screen module 14 and drive the flexible screen module 14 to bend and unfold.

[0045] The flexible screen module 14 can be in the form of a thin sheet or a thin plate, which has flexible and bendable properties. Figure 1 As shown, when the folding screen electronic device 10 is in the folded state, the flexible screen module 14 can be bent and accommodated in the first shell 11 and the second shell 13, that is, Figure 1 The folding screen electronic device 10 is an inward folding screen electronic device. Figure 2 As shown, when the folding screen electronic device 10 is in the folded state, the flexible screen module 14 is wrapped around the outside of the first shell 11 and the second shell 13, that is, Figure 2 The foldable screen electronic device 10 is an external foldable screen electronic device. A portion of the flexible screen module 14 can be fixed to the first housing 11, and another portion can be fixed to the second housing 13. The portion of the flexible screen module 14 corresponding to the hinge 12 needs to be bent (this portion can be called the bending zone), and this portion can be kept separate from the hinge 12 to avoid mutual interference.

[0046] The flexible screen module 14 can take on a certain shape when bent. For example, Figure 4The flexible screen module 14 can be used in an inward-folding screen electronic device. When the flexible screen module 14 is bent, its bending area BB can present a water droplet-like shape. A bending radius R of the most convex point of the outer surface S of the bending area BB can be defined. The bending radius R can be the radius of a fitted circle C passing through a convex point P and two points symmetrically distributed on either side of point P. The bending radius R can be between 1 mm and 5 mm, and can be, for example, 2.5 mm, 2.7 mm, or 5 mm.

[0047] Figure 5 The flexible screen module 14 in the embodiment can be used in an electronic device with an external folding screen. When the flexible screen module 14 is bent, its bending area BB can be substantially semicircular, and the entire flexible screen module 14 can be substantially U-shaped. A bending radius R of the most convex portion of the outer surface S of the bending area BB can be defined. The bending radius R can be the radius of a fitted circle C passing through a convex point P and two points symmetrically distributed on either side of point P. The bending radius R can be between 1 mm and 5 mm, and can be, for example, 5 mm.

[0048] It is understandable that Figure 4 and Figure 5 The shape shown is only an example. In fact, depending on the product structure, the flexible screen module 14 can also present other shapes in the bent state, such as the shape of a baseball bat for hitting a baseball.

[0049] like Figure 3 and Figure 6 As shown, the flexible screen module 14 of the first embodiment may include a stacked protective film 15 and a flexible screen 16. The flexible screen 16 has a light-emitting surface 16a (the surface that emits light, i.e., the surface that displays the image), the light-emitting surface 16a faces away from the first housing 11, the hinge 12, and the second housing 13, and the protective film 15 is in contact with the light-emitting surface 16a.

[0050] like Figure 6 As shown, the flexible screen 16 may include a flexible cover plate 161, a polarizer 162, a light emitting layer 163, a back film 164 and a support sheet 165 stacked in sequence. Figure 6 and Figure 3 As shown, the flexible cover 161 faces away from the first shell 11 , the hinge 12 and the second shell 13 , and the light emitting surface 16a , that is, the surface of the flexible cover 161 facing away from the polarizer 162 ; the support sheet 165 faces the first shell 11 , the hinge 12 and the second shell 13 .

[0051] The flexible cover 161 is used to protect the polarizer 162 and the light-emitting layer 163. The material constituting the flexible cover 161 may include transparent polyimide (CPI) or ultra-thin glass (UTG). The light-emitting layer 163 is capable of emitting light to enable the flexible screen 16 to display. The light-emitting layer 163 may include, for example, an organic light-emitting diode (OLED). The back film 164 (base film, BF) is attached to the back of the light-emitting layer 163 to protect the light-emitting layer 163. The support sheet 165 serves as a load-bearing member for the entire flexible screen 16 and can also ensure the flatness of the flexible screen 16. The support sheet 165 may be made of, for example, SUS stainless steel. The structure of the flexible screen 16 described above is merely an example. The specific structure of the flexible screen 16 may vary according to different actual needs, and this embodiment does not limit this.

[0052] like Figure 6 As shown, the protective film 15 may include a transparent hardened layer 151, a transparent polymer resin layer 152 and a transparent adhesive layer 153 stacked in sequence, wherein the transparent adhesive layer 153 is bonded to the light emitting surface 16a, and the transparent hardened layer 151 is away from the light emitting surface 16a.

[0053] The transparent hardened layer 151 can be made of, for example, acrylic polyurethane resin. The hardness of the transparent hardened layer 151 is relatively high, and can provide a relatively hard touch. For example, the pencil hardness of the transparent hardened layer 151 under a force of 1 kgf is ≥ 1H. The thickness of the transparent hardened layer 151 can be, for example, 1 μm-8 μm (including endpoint values), and a typical value can be 3 μm or 6 μm. The transparent hardened layer 151 can be formed on the surface of the transparent polymer resin layer 152 using a coating process. The specific operation of the coating process can be: applying a transparent hardening liquid on the surface of the transparent polymer resin layer 152, and then placing the transparent polymer resin layer 152 in an oven for baking, so that the transparent hardening liquid solidifies and stably adheres.

[0054] To increase the wear resistance of the transparent hardened layer 151, wear-resistant inorganic particles can be added to the transparent hardening liquid, and then the transparent hardening liquid mixed with the wear-resistant inorganic particles can be applied. To prevent the surface of the transparent hardened layer 151 from leaving a large number of fingerprints after the user touches the transparent hardened layer 151, an anti-fingerprint agent can also be added to the transparent hardening liquid. It is understood that the wear-resistant inorganic particles and the anti-fingerprint agent can coexist in the transparent hardened layer 151. In addition, the wear-resistant inorganic particles and the anti-fingerprint agent are not required.

[0055] The haze of the transparent hardened layer 151 represents the ratio of the light intensity scattered by the surface of the transparent hardened layer 151 to the total light intensity irradiating the surface of the transparent hardened layer 151. The lower the haze of the transparent hardened layer 151, the weaker the scattering of the transparent hardened layer 151, and the better the gloss and transparency of the transparent hardened layer 151. In Example 1, the haze of the transparent hardened layer 151 may be less than or equal to 1%, for example, it may be 0.15%, 0.4%, 0.5%, etc. This haze design can ensure that the gloss and transparency of the transparent hardened layer 151 meet the requirements, so as to ensure the display performance of the flexible screen 16. The surface roughness of the transparent hardened layer 151 can affect the haze. In order to achieve a haze level of less than or equal to 1%, the surface roughness of the transparent hardened layer 151 may be less than or equal to 1μm.

[0056] The transparent polymer resin layer 152 is the main layer in the protective film 15, and the transparent polymer resin layer 152 plays a main structural supporting role in the protective film 15. The transparent polymer resin layer 152 can be made of transparent polymer resin materials such as polyester film or epoxy resin film, for example. The transparent polymer resin layer 152 made of polyester film has better thermal performance and better dimensional stability when heated (for example, when baked in the above-mentioned oven) or wet. The transparent polymer resin layer 152 made of epoxy resin film has better deformation recovery performance. For example, it can still maintain a flat state after being bent 200,000 times. The thickness of the transparent polymer resin layer 152 can be, for example, 25μm-100μm (including the end value), and a typical value can be 50μm (when made of polyester film) or 38μm (when made of epoxy resin film).

[0057] The transmittance indicates the ratio of the amount of light passing through the material layer to the total amount of light irradiating the surface of the material layer. The higher the transmittance of the material layer, the better the light transmittance of the material layer. Since the human eye is more sensitive to light with a wavelength of 550nm, the transmittance of light with a wavelength of 550nm can be considered as the focus of the laminate in the protective film 15. For light with a wavelength of 550nm, the transmittance of the transparent polymer resin layer 152 in Example 1 can be greater than or equal to 85%, and a typical value can be 94%. This can ensure that the light transmittance of the transparent polymer resin layer 152 meets the display requirements of the flexible screen 16.

[0058] The transparent adhesive layer 153 can be made of acrylic polyurethane resin or silicone, for example. The thickness of the transparent adhesive layer 153 can be, for example, 15μm-50μm (including endpoints), and typical values can be, for example, 15μm, 30μm or 50μm. For light with a wavelength of 550nm, the transmittance of the transparent adhesive layer 153 can be, for example, greater than or equal to 90%, and a typical value can be 93%. This can ensure that the light transmittance of the transparent adhesive layer 153 meets the display requirements of the flexible screen 16. In Example 1, the transmittance of the transparent polymer resin layer 152 and the transparent adhesive layer 153 are both high, which can make the transmittance of the entire protective film 15 higher, for example, the transmittance of the protective film 15 can be greater than or equal to 88%, and a typical value can be 92.5%. This can ensure that the protective film 15 has high light transmittance and ensure the display performance of the flexible screen 16.

[0059] In the first embodiment, the transparent adhesive layer 153 may have at least one of the following designs:

[0060] 1. The modulus of the transparent adhesive layer 153 in a high temperature environment (for example, in an environment of 40°C-80°C) can be 15KPa-25KPa, and typical values can be, for example, 15KPa, 20KPa or 25KPa. This type of transparent adhesive layer 153 has a low modulus, and the transparent adhesive layer 153 is easy to deform. When bent, the internal stress of the transparent adhesive layer 153 is small, and it is not easy to peel off from the light-emitting surface 16a. The transparent adhesive layer 153 is limited to have the above modulus value in this high temperature environment in order to adapt to the actual use environment of the transparent adhesive layer 153 to ensure that the transparent adhesive layer 153 can be reliably combined with the light-emitting surface 16a during use. In addition, the above modulus range of the transparent adhesive layer 153 is relatively reasonable, which can avoid the reduction of adhesion due to too low modulus. Therefore, the protective film 15 of Example 1 can reduce or even avoid the risk of peeling between the protective film 15 and the flexible screen 16 by using the transparent adhesive layer 153 with a lower modulus, thereby improving the reliability of the flexible screen 16.

[0061] 2. Shape recovery rate refers to the ratio of the amount of deformation that can be recovered after the load is removed when the material is deformed under the action of a load to the total deformation. The shape recovery rate can be measured in the following way: at room temperature, a load of 10Kpa (which can be a torsional load) is continuously applied to the material sample (which can be processed into a strip or column) for 1 hour, and then the load is removed. When the material sample stops recovering the deformation, the shape recovery rate is measured. The shape recovery rate of the transparent adhesive layer 153 can be greater than or equal to 90%, and typical values can be, for example, 91% or 95%. This type of transparent adhesive layer 153 has less permanent deformation after multiple bending processes and can fit the light-emitting surface 16a very reliably. Therefore, it can reduce or even avoid the risk of peeling off between the protective film 15 and the flexible screen 16, thereby improving the reliability of the flexible screen 16.

[0062] 3. The peel force of the transparent adhesive layer 153 can indicate the strength of the bond between the transparent adhesive layer 153 and the light-emitting surface 16a. The peel force can be measured, for example, by adhering a sample of the transparent adhesive layer 153 to a target surface under test conditions. The sample is then lifted and folded 180 degrees. The sample is then pulled away from the target surface at a predetermined speed (e.g., 300 mm / min), and the pulling force applied during this process is measured. When the peel distance reaches a set value, the maximum pulling force measured is the sample's peel force. The unit of peel force can be gf / 25mm, representing the peel force measured when the sample is 25 mm wide. The peel force of the transparent adhesive layer 153 can be (200 gf - 1500 gf) / 25mm, with typical values being, for example, 200 gf / 25mm, 300 gf / 25mm, 900 gf / 25mm, and 1500 gf / 25mm. This transparent adhesive layer 153 has sufficient peeling force, ensuring that it remains bonded to the light-emitting surface 16a during repeated bending. This reduces or even eliminates the risk of peeling between the protective film 15 and the flexible screen 16, improving the reliability of the flexible screen 16. Furthermore, the peeling force of this transparent adhesive layer 153 is also suitable, preventing the protective film 15 from being difficult to remove from the flexible screen 16 due to excessive peeling force, which could hinder repair.

[0063] In Example 1, it can be understood that the above three designs of the transparent adhesive layer 153 can be combined arbitrarily, which can further reduce the risk of peeling between the protective film 15 and the flexible screen 16 and enhance the reliability of the flexible screen 16.

[0064] Based on the solution of the above embodiment 1, the transparent polymer resin layer 152 in the embodiment 2 may also have at least one of the following designs:

[0065] 1. The modulus of the transparent polymer resin layer 152 can be between 2 GPa and 15 GPa, with typical values ranging from 2 GPa, 4 GPa, 6 GPa, 10 GPa, and 15 GPa. This moderate modulus of the transparent polymer resin layer 152 makes it easier to bend, ensuring a secure bond between the transparent adhesive layer 153 and the light-emitting surface 16a. This reduces stress at the interface between the transparent adhesive layer 153 and the light-emitting surface 16a, thereby reducing the risk of delamination between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0066] 2. The elongation at break of the transparent polymer resin layer 152 is greater than or equal to 15%, with typical values being 20%, 30%, or 40%. Elongation at break represents the ratio of the elongated length of a material when it breaks under tension to its length before stretching. A transparent polymer resin layer 152 with this elongation at break exhibits superior toughness and can adapt well to the reciprocating deformation during bending, thereby reducing the risk of delamination between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0067] 3. After being bent multiple times, the transparent polymer resin layer 152 will form a structure with straight parts at both ends and a bent part between the two straight parts. The angle between the two straight parts in this structure is called the plane angle. The plane angle can characterize the deformation recovery ability of the transparent polymer resin layer 152. In Example 2, the plane angle of the transparent polymer resin layer 152 can be greater than or equal to 150°, and typical values can be 165°, 170°, and 180° (for example, the transparent polymer resin layer 152 made of epoxy resin film can reach a plane angle of 180°). This kind of transparent polymer resin layer 152 has a strong deformation recovery ability and is not easy to warp after multiple bending, which is beneficial to reduce the risk of peeling between the protective film 15 and the flexible screen 16 and improve the reliability of the flexible screen 16.

[0068] In the second embodiment, it is understood that the above three designs of the transparent polymer resin layer 152 can be combined in any combination; furthermore, the above three designs of the transparent polymer resin layer 152 can be combined in any combination with the above three designs of the transparent adhesive layer 153 in the first embodiment. This can further reduce the risk of peeling between the protective film 15 and the flexible screen 16, thereby enhancing the reliability of the flexible screen 16.

[0069] Based on the solutions of the first and / or second embodiments described above, the elongation at break of the transparent hardened layer 151 in the third embodiment can be greater than or equal to 2%, with a typical value of 2.5%. The transparent hardened layer 151 with this elongation at break has good toughness and can well adapt to the reciprocating deformation during the bending process, thereby reducing the risk of separation between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0070] In Example 3, by simultaneously employing the three aforementioned designs for the transparent polymer resin layer 152 of Example 2 and the three aforementioned designs for the transparent adhesive layer 153 of Example 1, the reliability of the protective film 15 can be greatly improved. For example, actual verification has shown that, after a flexible screen module 14 with a bending radius R of 1 mm ≤ 5 mm has undergone at least 40,000 bend tests, the protective film 15 and the flexible screen 16 remain reliably bonded, with no surface damage, whitening, or cracking on the protective film 15.

[0071] Different from the above-mentioned embodiments 1 to 3, in order to reduce the risk of peeling between the protective film 15 and the flexible screen 16 and improve the reliability of the flexible screen 16, the transparent polymer resin layer 152 in the fourth embodiment can have at least one of the following designs:

[0072] 1. The modulus of the transparent polymer resin layer 152 is 2GPa-4GPa, with typical values being 2GPa, 3GPa, or 4GPa. This type of transparent polymer resin layer 152 has a relatively low modulus (conventional transparent polymer resin layers have a higher modulus, such as 5.4GPa). The transparent polymer resin layer 152 is easily bent, ensuring a reliable bond between the transparent adhesive layer 153 and the light-emitting surface 16a. This reduces the stress at the interface between the transparent adhesive layer 153 and the light-emitting surface 16a, thereby reducing the risk of peeling between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16. Practical verification has shown that using a transparent polymer resin layer 152 with a modulus of 2GPa-4GPa can significantly improve the peeling problem.

[0073] 2. The elongation at break of the transparent polymer resin layer 152 is greater than or equal to 25%, with typical values being 30%, 45%, or 70%. A transparent polymer resin layer 152 with this elongation at break exhibits superior toughness and can adapt well to the reciprocating deformation during bending, thereby reducing the risk of separation between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0074] Based on the solution of the fourth embodiment, the transparent adhesive layer 153 in the fifth embodiment may also have at least one of the following designs:

[0075] 1. The shape recovery rate of the transparent adhesive layer 153 is greater than or equal to 80%, with typical values being 85%, 90%, or 93%. This transparent adhesive layer 153 exhibits minimal permanent deformation after multiple bending processes, allowing it to adhere reliably to the light-emitting surface 16a. This reduces or even eliminates the risk of separation between the protective film 15 and the flexible screen 16, thereby improving the reliability of the flexible screen 16.

[0076] 2. The peel force of the transparent adhesive layer 153 is (50gf-2000gf) / 25mm, with typical values such as 50gf / 25mm, 100gf / 25mm, 300gf / 25mm, 900gf / 25mm, and 1500gf / 25mm. This type of transparent adhesive layer 153 has sufficient peel force, ensuring that it remains bonded to the light-emitting surface 16a during repeated bending. This reduces or even eliminates the risk of peeling between the protective film 15 and the flexible screen 16, improving the reliability of the flexible screen 16. Furthermore, the peel force of this type of transparent adhesive layer 153 is also suitable, preventing the protective film 15 from being difficult to remove from the flexible screen 16 due to excessive peel force, which could hinder repair.

[0077] In the fifth embodiment, it is understood that the above two designs of the transparent adhesive layer 153 and the above two designs of the transparent polymer resin layer 152 in the fourth embodiment can be combined in any manner. This can further reduce the risk of peeling between the protective film 15 and the flexible screen 16 and enhance the reliability of the flexible screen 16.

[0078] Based on the solutions of the fourth and / or fifth embodiments described above, the elongation at break of the transparent hardened layer 151 in the sixth embodiment can be greater than or equal to 2%, with a typical value of 2.5%. The transparent hardened layer 151 with this elongation at break has good toughness and can well adapt to the reciprocating deformation during the bending process, thereby reducing the risk of separation between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0079] In Example 6, the simultaneous use of the two designs for the transparent adhesive layer 153 in Example 5 and the three designs for the transparent polymer resin layer 152 in Example 4 significantly improves the reliability of the protective film 15. For example, actual verification has shown that even after a flexible screen module 14 with a bending radius R of 1 mm ≤ 5 mm has undergone at least 40,000 bends, the protective film 15 and the flexible screen 16 remain reliably bonded, with no surface damage, whitening, or cracking on the protective film 15.

[0080] Unlike Examples 1 to 6 above, to reduce the risk of peeling between the protective film 15 and the flexible screen 16 and improve the reliability of the flexible screen 16, the transparent hardened layer 151 in Example 7 can have an elongation at break greater than or equal to 2.5%, with typical values being 2.7% and 3.2%. This elongation provides the transparent hardened layer 151 with improved toughness and adapts well to the reciprocating deformation during bending, thereby reducing the risk of peeling between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0081] Based on the solution of the seventh embodiment, the transparent adhesive layer 153 in the eighth embodiment may also have at least one of the following designs:

[0082] 1. The shape recovery rate of the transparent adhesive layer 153 is greater than or equal to 80%, with typical values being 85%, 90%, or 93%. This transparent adhesive layer 153 exhibits minimal permanent deformation after multiple bending processes, allowing it to adhere reliably to the light-emitting surface 16a. This reduces or even eliminates the risk of separation between the protective film 15 and the flexible screen 16, thereby improving the reliability of the flexible screen 16.

[0083] 2. The peel force of the transparent adhesive layer 153 is (50gf-2000gf) / 25mm, with typical values such as 50gf / 25mm, 100gf / 25mm, 300gf / 25mm, 900gf / 25mm, and 1500gf / 25mm. This type of transparent adhesive layer 153 has sufficient peel force, ensuring that it remains bonded to the light-emitting surface 16a during repeated bending. This reduces or even eliminates the risk of peeling between the protective film 15 and the flexible screen 16, improving the reliability of the flexible screen 16. Furthermore, the peel force of this type of transparent adhesive layer 153 is also suitable, preventing the protective film 15 from being difficult to remove from the flexible screen 16 due to excessive peel force, which could hinder repair.

[0084] Based on the solutions of the seventh or eighth embodiment, the transparent polymer resin layer 152 in the ninth embodiment may further have at least one of the following designs:

[0085] 1. The modulus of the transparent polymer resin layer 152 can be between 2 GPa and 15 GPa, with typical values ranging from 2 GPa, 4 GPa, 6 GPa, 10 GPa, and 15 GPa. This moderate modulus of the transparent polymer resin layer 152 makes it easier to bend, ensuring a secure bond between the transparent adhesive layer 153 and the light-emitting surface 16a. This reduces stress at the interface between the transparent adhesive layer 153 and the light-emitting surface 16a, thereby reducing the risk of delamination between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0086] 2. The elongation at break of the transparent polymer resin layer 152 is greater than or equal to 15%, with typical values being 20%, 30%, or 40%. A transparent polymer resin layer 152 with this elongation at break exhibits good toughness and can adapt well to the reciprocating deformation during bending, thereby reducing the risk of separation between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0087] 3. The planar angle of the transparent polymer resin layer 152 can be greater than or equal to 150°, with typical values being 165°, 170°, or 180° (for example, a transparent polymer resin layer 152 made of epoxy resin film can achieve a planar angle of 180°). This type of transparent polymer resin layer 152 has a strong deformation recovery ability and is not easily warped after multiple bends, thereby reducing the risk of separation between the protective film 15 and the flexible screen 16 and improving the reliability of the flexible screen 16.

[0088] In Example 9, it is understood that the three designs of the transparent polymer resin layer 152 can be combined in any combination; furthermore, the three designs of the transparent polymer resin layer 152 can be combined in any combination with the design of the transparent hardened layer 151 in Example 7 and the two designs of the transparent adhesive layer 153 in Example 8. This can further reduce the risk of separation between the protective film 15 and the flexible screen 16, thereby enhancing the reliability of the flexible screen 16.

[0089] In Example 9, the simultaneous use of the three aforementioned designs for the transparent polymer resin layer 152 and the two aforementioned designs for the transparent adhesive layer 153 in Example 8 significantly improves the reliability of the protective film 15. For example, actual verification has shown that, after a flexible screen module 14 with a bending radius R of 1 mm ≤ 5 mm has undergone at least 40,000 bends, the protective film 15 and the flexible screen 16 remain reliably bonded, with no surface damage, whitening, or cracking on the protective film 15.

[0090] In the tenth embodiment, the transparent hardened layer 151 , the transparent adhesive layer 153 , and the transparent polymer resin layer 152 may be designed as follows:

[0091] The elongation at break of the transparent hardened layer 151 is greater than or equal to 2.5%, and typical values may be 2.7% or 3.2%.

[0092] The transparent adhesive layer 153 has at least one of the following features: 1. The modulus of the transparent adhesive layer 153 in an environment of 40°C to 80°C is 15 kPa to 25 kPa, with typical values being 15 kPa, 20 kPa, or 25 kPa. 2. The shape recovery rate of the transparent adhesive layer 153 is greater than or equal to 90%, with typical values being 91% or 95%. 3. The peel force of the transparent adhesive layer 153 is (200 gf to 1500 gf) / 25 mm, with typical values being 200 gf / 25 mm, 300 gf / 25 mm, 900 gf / 25 mm, or 1500 gf / 25 mm.

[0093] The transparent polymer resin layer 152 has at least one of the following features: 1. The modulus of the transparent polymer resin layer 152 is between 2 GPa and 4 GPa, with typical values being 2 GPa, 3 GPa, and 4 GPa. 2. The elongation at break of the transparent polymer resin layer 152 is greater than or equal to 25%, with typical values being 30%, 45%, and 70%. 3. The plane angle of the transparent polymer resin layer 152 is greater than or equal to 150°, with typical values being 165°, 170°, and 180°.

[0094] In Example 10, the comprehensive design of the transparent hardened layer 151, transparent adhesive layer 153, and transparent polymer resin layer 152 significantly enhances the reliability of the protective film 15. For example, actual verification has shown that even after a flexible screen module 14 with a bending radius R of 1 mm ≤ 5 mm has undergone at least 40,000 bends, the protective film 15 and the flexible screen 16 remain reliably bonded, with no surface damage, whitening, or cracking on the protective film 15.

[0095] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A protective film, characterized in that: The protective film is used to protect the flexible screen, the flexible screen has a light-emitting surface, and the protective film includes a transparent hardened layer, a transparent polymer resin layer, and a transparent adhesive layer stacked in sequence, wherein the transparent adhesive layer is used to bond to the light-emitting surface of the flexible screen; The peeling force of the transparent adhesive layer is (200gf-1500gf) / 25mm; The modulus of the transparent polymer resin layer is 2GPa-15GPa; The elongation at break of the transparent hardened layer is greater than or equal to 2.5%.

2. The protective film according to claim 1, wherein The thickness of the transparent hardened layer is 1 μm-8 μm; and / or, The thickness of the transparent polymer resin layer is 25 μm-100 μm; and / or, The thickness of the transparent adhesive layer is 15 μm-50 μm.

3. The protective film according to claim 1 or 2, characterized in that: The shape recovery rate of the transparent adhesive layer is greater than or equal to 90%; and / or, The modulus of the transparent adhesive layer in an environment of 40° C. to 80° C. is 15 KPa to 25 KPa.

4. The protective film according to any one of claims 1 to 3, characterized in that: The elongation at break of the transparent polymer resin layer is greater than or equal to 15%.

5. The protective film according to any one of claims 1 to 4, characterized in that: The material of the transparent hardened layer is acrylic polyurethane resin; and / or, The material of the transparent polymer resin layer is a polyester film or an epoxy resin film; and / or, The material of the transparent adhesive layer is acrylic polyurethane resin or silicone.

6. The protective film according to any one of claims 1 to 5, characterized in that: The transmittance of light with a wavelength of 550 nm through the protective film is greater than or equal to 88%.

7. The protective film according to claim 6, characterized in that The transmittance of light with a wavelength of 550 nm to the transparent polymer resin layer is greater than or equal to 85%, and the transmittance of light with a wavelength of 550 nm to the transparent adhesive layer is greater than or equal to 90%.

8. The protective film according to any one of claims 1 to 7, characterized in that: The haze of the transparent hardened layer is less than or equal to 1%.

9. The protective film according to claim 8, characterized in that The surface roughness of the transparent hardened layer is less than or equal to 1 μm.

10. The protective film according to any one of claims 1 to 9, characterized in that: The modulus of the transparent polymer resin layer is 2GPa-4GPa.

11. The protective film according to any one of claims 1 to 10, characterized in that: The thickness of the transparent hardened layer is 3 μm-6 μm; and / or, The thickness of the transparent polymer resin layer is 50 μm-100 μm.

12. An electronic device, characterized in that: The electronic device comprises a flexible screen and the protective film according to any one of claims 1 to 11, wherein the protective film is arranged on a light-emitting surface side of the flexible screen.

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