Protective film and preparation method thereof

Abstract

The invention provides a protective film and a preparation method thereof.The protective film comprises a main body part and an edge part which are integrally connected, the edge part is arranged at the edge of the main body part, the surface, used for being attached to a screen, of the protective film is defined as the lower surface, and the surface, opposite to the lower surface, of the other side is defined as the upper surface; and the lower surface of the edge part protrudes out of the lower surface of the main body part. According to the protective film and the preparation method thereof provided by the invention, the problems of warping and dust entering of the edge of a screen can be effectively improved, and meanwhile, an original film can be protected and prevented from warping and scratching.

Description

Technical Field

[0001] This application relates to the field of screen protector technology, and in particular to a screen protector and its preparation method. Background Technology

[0002] Currently, foldable screen phones on the market all have a special original screen protector designed for flexible screens on the outer surface of their foldable screens. This original screen protector is not only a protective layer for the screen, but also an important component of the screen structure. This original screen protector cannot be removed by the user; otherwise, it may damage the screen and void the warranty. However, this original screen protector only covers the display area of ​​the foldable screen, leaving the surrounding non-display areas uncovered. This makes it easy for dust to get into the edges of the original screen protector and for it to peel up, affecting both aesthetics and usability. In the process of developing this application, the inventors discovered that the existing technology has at least the following problems: Most existing mobile phone screen protectors are flat and of uniform thickness. If foldable screens still use traditional screen protectors, applying another flat screen protector on top of the original screen protector will not improve the problem of dust getting into the edges and peeling up. Furthermore, because the edges of the original screen protector protrude from the surface of the foldable screen, using traditional screen protectors not only fails to solve the problem of dust getting into the original screen protector, but may also exacerbate the problem. Summary of the Invention

[0003] Based on this, this application provides a protective film to improve the problems of easy peeling and dust ingress of the edges of the protective film in the prior art, and to achieve better protection for the screen and the original film.

[0004] To achieve the above objectives, the technical solution of this application embodiment is implemented as follows: On one hand, this application provides a protective film, which includes an integrally connected main body and an edge portion. The edge portion is located at the edge of the main body. The surface of the protective film used to be attached to one side of the screen is defined as the lower surface, and the other side surface opposite to the lower surface is defined as the upper surface. The lower surface of the edge portion protrudes from the lower surface of the main body.

[0005] In one embodiment, the main body includes a first membrane, a second membrane, and a bending region membrane located between the first membrane and the second membrane, the bending region membrane connecting the first membrane and the second membrane, and the edge portion being disposed at the edge of the first membrane and the second membrane.

[0006] In one embodiment, clearance grooves are provided on opposite sides of the bending region membrane. The clearance grooves are located at the edge of the bending region membrane connecting the first membrane and the second membrane, and are formed by the edge of the bending region membrane being recessed towards the center.

[0007] In one embodiment, the connection points between the clearance groove and the first membrane, the second membrane, and the edge portion are smoothly transitioned.

[0008] In one embodiment, the protective film further includes an adhesive layer disposed in a cavity formed by the main body portion and the edge portion.

[0009] In one embodiment, the thickness of the main body portion ranges from 0.02 to 0.05 mm.

[0010] In one embodiment, the protective film is made of UTG material.

[0011] In one embodiment, the protective film is a tempered glass film.

[0012] In one embodiment, the lower surface of the edge portion is provided with a black edge formed by ink.

[0013] On the other hand, embodiments of this application provide a method for preparing a protective film, comprising the following steps: Provide single-piece substrates; The outer contour of the substrate is processed to remove excess material from the outer contour; The substrate is thinned in the middle to form a main body in the middle and an edge part at the edge of the main body. The surface of the substrate used to attach to one side of the screen is defined as the lower surface, and the other side surface opposite to the lower surface is defined as the upper surface. The lower surface of the edge part protrudes from the lower surface of the main body.

[0014] In one embodiment, before processing the outer contour of the substrate, the method further includes: stacking multiple substrates one on top of the other, and bonding and fixing two adjacent substrates together with a soluble adhesive.

[0015] In one embodiment, after processing the outer contour of the substrate, the method further includes: dissolving the soluble adhesive between the multiple bonded substrates, separating the multiple bonded substrates into a single substrate, and removing residual adhesive from the surface of the substrate.

[0016] In one embodiment, the step of processing the outer contour of the substrate further includes: processing the two ends of the substrate used to form the bending area membrane to form clearance grooves, wherein the clearance grooves are formed by cutting from the edge of the substrate towards the center.

[0017] In one embodiment, before thinning the middle part of the substrate, the method further includes: covering the entire upper surface of the substrate with a layer of protective oil, and covering the lower surface of the substrate with a layer of protective oil at the position corresponding to the edge.

[0018] In one embodiment, the thinning process of the middle part of the substrate specifically includes: placing the substrate in a hydrofluoric acid solution for etching, so that the thickness of the area of ​​the substrate without protective oil is reduced, thereby forming the main body and the edge.

[0019] In one embodiment, after thinning the middle portion of the substrate, the process further includes: tempering the thinned substrate.

[0020] In one embodiment, after tempering the thinned substrate, the method further includes: screen printing ink on the lower surface of the edge portion to form a black edge on the edge portion.

[0021] In one embodiment, after screen printing ink on the lower surface of the edge portion, the method further includes: attaching an adhesive layer in the cavity formed by the main body portion and the edge portion, and covering the adhesive layer with a release film.

[0022] This application has at least the following beneficial effects: The protective film and its preparation method provided in this application have a thickness at the edge of the protective film that is greater than the thickness of the main body. After its lower surface is attached to the original film of the folding screen, it can offset the height difference caused by the original film, making the surface of the folding screen flat. At the same time, it can make the protective film completely adhere to the surface of the folding screen, thereby reducing the possibility of dust entering the edge and lifting. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the installation structure of the protective film and the foldable screen according to an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of the front view structure of the protective film according to an embodiment of this application.

[0025] Figure 3 for Figure 2 A schematic diagram of the bending area of ​​the protective film.

[0026] Figure 4 for Figure 2 An enlarged schematic diagram of the structure at point A.

[0027] Figure 5 This is a schematic diagram of the structure of the protective film after bending according to an embodiment of this application.

[0028] Figure 6 for Figure 5 Enlarged schematic diagram of the structure at point B.

[0029] The meanings of the labels in the attached diagram are as follows: 1. Protective film; 11. Main body; 12. Edge; 13. Clear groove; 14. Bending area film; 15. Adhesive layer; 16. First film; 17. Second film; 2. Original film; 3. Folding screen. Detailed Implementation

[0030] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the ways in which this application may be implemented. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] In the description of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are used 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 on this application. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Please see Figure 1 In this embodiment of the application, the protective film 1 is used to be attached to the original film 2 of the folding screen 3. The folding screen 3 includes a display area and a non-display area surrounding the display area. The original film 2 is attached to the display area, and the non-display area of ​​the folding screen 3 is exposed, forming a height difference between the edge of the original film 2 and the surface of the folding screen 3.

[0035] like Figure 2 and Figure 3As shown, the protective film 1 of this embodiment includes an integrally connected main body 11 and edge portion 12. The main body 11 is located in the middle of the protective film 1, and the edge portion 12 surrounds the periphery of the main body 11. The surface of the protective film 1 used to adhere to the screen is defined as the lower surface, and the opposite surface is defined as the upper surface. The upper surface of the protective film 1 can be a single plane, or the edge of the upper surface of the protective film 1 can be chamfered or rounded. The lower surface of the edge portion 12 protrudes from the lower surface of the main body 11. In this embodiment, the thickness of the edge portion 12 is greater than the thickness of the main body 11. The main body 11 includes a first film body 16, a second film body 17, and a bending region film body 14 located between the first film body 16 and the second film body 17. The bending region film body 14 connects the first film body 16 and the second film body 17. The edge portion 12 is located at the edge of the first film body 16 and the second film body 17. That is, a bending area film 14 is provided in the middle of the main body 11, a first film 16 is provided on one side of the bending area film 14, and a second film 17 is provided on the other side. There are two edge portions 12, one edge portion 12 is provided around the edge of the first film 16, and the other edge portion 12 is provided around the edge of the second film 17. The area of ​​the protective film 1 is basically the same as the area of ​​the folding screen 3, so that the area of ​​the protective film 1 is matched with the area of ​​the folding screen 3, which can achieve full coverage of the folding screen 3 and provide a comprehensive protection effect for the folding screen 3. At the same time, it reduces the accumulation of dust on the surface of the folding screen 3, which would cause the problem of dust entering the edge of the protective film 1 and lifting. The edge portions 12 located around the main body 11 are thicker than the thickness of the main body 11, thereby offsetting the height difference problem caused by the original film 2, so that the protective film 1 can perfectly adhere to the surface of the folding screen 3 and reduce the possibility of dust entering. At both ends of the membrane 14 in the bending area, there are no thicker edge portions 12, which can effectively prevent the protective film 1 from breaking during bending due to inconsistent thickness.

[0036] Specifically, the thickness of the main body 11 and the edge portion 12 can be made uniform, making it easier to maintain the flatness of the protective film 1 surface. Simultaneously, the edge portion 12 can cover the non-display area of ​​the foldable screen 3, while the main body 11 covers the display area. This results in a thinner protective film 1 in the display area, increasing operational sensitivity, and the uniform thickness of the main body 11 ensures consistent operational sensitivity across the entire display area, providing a better user experience. The slightly thicker edge portion 12 compensates for the height difference caused by the original film 2, achieving a perfect fit between the edge portion 12 and the non-display area of ​​the foldable screen 3, effectively preventing dust from entering from the edge of the protective film 1. In this embodiment, the bending area film 14 extends a certain width to both sides of the folding hinge of the foldable screen 3. Since no edge portion 12 is provided at the corresponding position of the bending area film 14, the edge portion 12 is divided into two by the bending area film 14. The two edge portions 12 are symmetrically arranged with respect to the center of the bending area film 14, and the edge portions 12 surround all edges of the main body 11 except for the bending area film 14. That is to say, the main body 11 has edge portions 12 at all positions except the position corresponding to the bending area film 14. In other words, the edge portions 12 are arranged to avoid the bending area film 14, which can better protect the folding screen 3 and reduce the stress on the bending area film 14 when bending, thus extending the service life of the protective film 1.

[0037] like Figures 3 to 6 As shown, to further improve the bending resistance of the membrane 14 in the bending area and extend its service life, a relief groove 13 can also be provided. The relief groove 13 is provided at the edge where the membrane 14 in the bending area connects the first membrane 16 and the second membrane 17. The relief groove 13 is formed by the edge of the membrane 14 in the bending area recessing towards the center. That is, the edge of the main body 11 at the relief groove 13 is recessed inward, specifically, it can be recessed until the outer edge of the relief groove 13 is flush with the inner edge of the edge portion 12, or the outer edge of the relief groove 13 is flush with the outer edge of the original membrane 2. By providing the relief groove 13 at the membrane 14 in the bending area, it is easier to position and shape the edge portion 12 during the manufacturing process of the protective film 1. At the same time, the relief groove 13 can further reduce the stress on the membrane 14 in the bending area when bending, thereby extending the service life of the protective film 1. The connection between the edge of the relief groove 13 and the first membrane 16, the second membrane 17 and the edge portion 12 can be made with a smooth transition to further reduce the possibility of stress concentration.

[0038] like Figure 1As shown, the protective film 1 in this embodiment further includes an adhesive layer 15, which is disposed in the cavity formed by the main body 11 and the edge portion 12. The total thickness of the main body 11, the adhesive layer 15, and the original film 2 is equal to the thickness of the edge portion 12. That is, the adhesive layer 15 covers all areas of the lower surface of the protective film 1 except for the edge portion 12. In other words, adhesive is provided on the main body 11, but not on the edge portion 12. Since there is no adhesive layer 15 on the edge portion 12, even if there is slight dust accumulation at the edge of the protective film 1, the dust is not easily adhered to the edge of the protective film 1. The total thickness of the main body 11, the adhesive layer 15, and the original film 2 is exactly the same as the thickness of the edge portion 12. This can offset the height difference caused by the thickness of the original film 2, so that when the protective film 1 is attached to the original film 2, it can perfectly fit the surface of the folding screen 3, and no gaps will be formed in the non-display area of ​​the folding screen 3 due to the original film 2, thereby reducing the possibility of dust accumulation at the edge of the protective film 1.

[0039] In some embodiments, the thickness of the main body 11 can range from 0.02 to 0.05 mm, preferably 0.03 mm. The thickness of the edge portion 12 can be 0.15 to 0.2 mm. The protective film 1 in this embodiment is made of UTG (ultra-thin flexible glass) material. The main body 11 corresponds to the display area of ​​the foldable screen 3, that is, the control area of ​​the touch screen. The thinner thickness of the main body 11 can improve the sensitivity of touch. In some embodiments, the protective film 1 can also be a tempered glass film that has undergone tempering treatment. A black edge formed by ink is provided on the lower surface of the edge portion 12. Even if a small amount of dust enters the edge of the protective film 1, it will be blocked by the black edge, making the screen look cleaner overall.

[0040] This application also provides a method for preparing a protective film 1, which specifically includes the following steps: S1. Substrate provision step: Provide a single substrate.

[0041] A single UTG substrate is provided, the thickness of which is equal to the thickness of the edge portion 12, and the area of ​​the substrate is not less than the area of ​​the foldable screen 3.

[0042] Specifically, a large ultra-thin glass substrate can be provided, with a thickness not exceeding 0.2 mm, for example, 0.16 mm, and the substrate must meet the requirements for flexibility and strength. The large substrate is then cut and slit according to the design dimensions using equipment such as a glass cutting machine, resulting in multiple individual substrate pieces. These individual substrate pieces are then placed in a tray.

[0043] S2, Optical Curing Lamination Step: Multiple substrates are stacked one on top of the other, and adjacent substrates are bonded and fixed with soluble adhesive.

[0044] Adhesive is applied to the surface of the substrate using a UV dispensing machine, with a dispensing thickness of approximately 0.05mm. Multiple substrates are then bonded together using UV-cured adhesive and cured. For example, five individual substrates can be bonded together, overlapping vertically. This step facilitates subsequent processing, as thin substrates are difficult to process.

[0045] S3. Processing steps: Process the outer contour of the substrate to remove excess material from the outer contour.

[0046] The shape of the substrate after multiple pieces are bonded and fixed is processed to make the area of ​​the substrate consistent with the area of ​​the foldable screen 3.

[0047] When a glass cutting machine slices a whole substrate, sharp corners remain at the four corners of the cut single substrate piece. At this step, a CNC machining center can be used to sculpt the substrate's shape. For example, the substrate's shape can be finely machined to reduce the dimensional difference between it and the shape of the foldable screen 3. Simultaneously, the sharp corners can be ground and rounded to prevent stress concentration. For example, a 1200# grinding wheel can be selected for the CNC machining center to ensure smooth edges and reduce micro-cracks.

[0048] When a relief groove 13 is provided on the protective film 1, the relief groove 13 also needs to be processed in this step. The two ends of the substrate used to form the bending area film 14 are processed to form the relief groove 13, which is formed by cutting from the edge of the substrate towards the center. Specifically, the substrate edge corresponding to the bending area film 14 can be cut towards the center, causing the two ends of the substrate corresponding to the bending area film 14 to be recessed inward by a certain distance. Specifically, the outer edge of the relief groove 13 can be flush with the inner wall of the edge portion 12, or located inside the inner wall of the edge portion 12. When processing the relief groove 13, the connection points between the relief groove 13 and the first film 16, the second film 17, and the edge portion 12 are also processed to ensure a smooth transition and avoid stress concentration.

[0049] S4. Separation step: Dissolve the soluble adhesive between multiple bonded substrates to separate the multiple fixed substrates into individual substrates, and remove residual adhesive from the surface of the substrates.

[0050] Specifically, after the substrate pieces have been shaped, they are immersed in a UV degradation solution, ensuring the entire semi-finished product is completely submerged. The solution is then heated to 40-60℃. After immersion for 1-3 hours, the substrate pieces are removed and separated into individual pieces. Heating and immersion improve the dissolution efficiency of the UV adhesive. The specific immersion time depends on the choice of UV adhesive and UV degradation solution.

[0051] After the substrate is separated into individual sheets, a special UV adhesive solvent is used to dissolve and remove the residual adhesive on the substrate surface. UV adhesive solvents are mostly mixtures of organic solvents, but environmentally friendly bio-based solvents (such as citrate derivatives) and alcohols (such as isopropanol) can also be used. These solvents have the advantages of low toxicity and biodegradability, making them suitable for use in precision electronic glass.

[0052] S5. Step for applying protective oil: Cover the entire upper surface of the substrate with a layer of protective oil, and cover the lower surface of the substrate with a layer of protective oil at the corresponding edge 12. The protective oil is used to protect the surface of the substrate and prevent the surface of the substrate from being corroded by acid.

[0053] Specifically, a protective oil is screen-printed onto the entire upper surface of the substrate using a screen printing machine. Then, a layer of protective oil is screen-printed onto the lower surface of the substrate at the corresponding edge 12, with a screen printing thickness of approximately 15-20 μm. After screen printing, the screen-printed ink is baked dry.

[0054] S6. Etching and thinning step: The middle part of the substrate is thinned to form a main body 11 in the middle and an edge part 12 at the edge of the main body 11. The surface of the substrate used to attach to the screen is defined as the lower surface, and the opposite surface is defined as the upper surface. The upper surface of the edge part 12 and the upper surface of the main body 11 are on the same plane, and the lower surface of the edge part 12 protrudes from the lower surface of the main body 11.

[0055] A bending zone film 14 is provided in the middle of the main body 11, and edge portions 12 are provided at the edges of the main body 11 on both sides of the bending zone film 14. The main body 11 is thinned so that the thickness of the edge portions 12 is greater than the thickness of the main body 11. The substrate is etched in a hydrofluoric acid solution to thin the thickness of the areas of the substrate without protective oil, thereby forming the main body 11 and the edge portions 12, and the surface of the main body 11 is recessed inward relative to the edge portions 12.

[0056] Specifically, the substrate, after being screen-printed with protective oil, can be immersed in a hydrofluoric acid solution for etching. During this process, the areas not covered by the protective oil are etched by the hydrofluoric acid solution, forming recessed cavities. The depth of these cavities is set according to actual needs, for example, it can be 0.05-0.12 mm. In this embodiment, the thickness of the main body 11 after thinning is approximately 0.03 mm. After etching, the substrate surface is cleaned with water to remove the hydrofluoric acid solution adhering to the substrate surface. The mass concentration of the hydrofluoric acid solution can be 25%-35%, preferably 28%-32%, to improve etching efficiency and quality; the etching temperature is 30-50°C; and the etching time is 10-50 minutes.

[0057] After etching, the substrate can be placed in a sodium hydroxide solution at 60-100℃ to remove the protective oil from its surface. Once the acid-resistant protective oil is dissolved and removed, the substrate surface can be cleaned using an ultrasonic cleaner and then thoroughly rinsed with ultrapure water. The sodium hydroxide concentration can be in the range of 15%-30%, preferably 15%-20%; the processing temperature range is 60-100℃, preferably 60-80℃; and the processing time is 2-3 minutes. Choosing an appropriate concentration of sodium hydroxide solution and a suitable processing time ensures thorough removal of the protective oil while avoiding corrosion of the substrate by the alkaline solution. Selecting a suitable processing temperature improves the efficiency of protective oil removal.

[0058] S7. Tempering step: Temper the thinned substrate.

[0059] After the etching and thinning process, the overall shape of the substrate is basically formed. At this point, the formed UTG substrate can be subjected to glass chemical strengthening to improve the strength of the glass by changing the surface stress. This step can be performed using conventional glass tempering processes, which will not be elaborated here.

[0060] S8. Silk screen printing black edge step: Silk screen ink is applied to the lower surface of the edge portion 12 to form a black edge on the edge portion 12.

[0061] Black ink is screen-printed on the lower surface of edge 12 to form a black edge. This step uses a conventional screen-printing process and will not be described in detail. S9. Adhesive application step: Apply adhesive layer 15 to the cavity formed by the main body 11 and the edge 12, and place release film on the outside of adhesive layer 15. Adjust the thickness of adhesive layer 15 according to the thickness of original film 2 and the thickness of main body 11 so that the total thickness of main body 11, adhesive layer 15 and original film 2 is equal to the thickness of edge 12.

[0062] Cover all recessed areas except the edge portion 12 with a layer of AB adhesive, that is, cover the entire lower surface of the main body portion 11 with adhesive. The adhesive application can be carried out by a laminating machine using conventional processes, which will not be described in detail here.

[0063] The protective film provided in this application embodiment can achieve full coverage of the foldable screen, and since it is attached to the original film, it can prevent the original film from being worn, getting dust inside, or peeling. The protective film has a height difference between its main body and edges, which perfectly offsets the height difference between the original film and the foldable screen, ensuring a perfect fit between the protective film and the screen surface and reducing the possibility of dust getting into the edges. Simultaneously, the edges of the protective film are not glued and have a black border, further reducing the possibility of dust accumulation. The black border also helps to conceal dust, resulting in a cleaner appearance. The protective film provided in this application embodiment is simple to manufacture and easy to control. The protective film is made of UTG material, giving it high hardness, good anti-aging properties, and excellent transparency.

[0064] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0065] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A protective film, characterized in that, The protective film includes an integrally connected main body and an edge portion. The edge portion is located at the edge of the main body. The surface of the protective film used to be attached to one side of the screen is defined as the lower surface, and the other surface opposite to the lower surface is defined as the upper surface. The lower surface of the edge portion protrudes from the lower surface of the main body.

2. The protective film as described in claim 1, characterized in that, The main body includes a first membrane, a second membrane, and a bending region membrane located between the first membrane and the second membrane. The bending region membrane connects the first membrane and the second membrane, and the edge portion is located at the edge of the first membrane and the second membrane.

3. The protective film as described in claim 2, characterized in that, Clearance grooves are provided on opposite sides of the bending region membrane. The clearance grooves are located at the edge of the bending region membrane connecting the first membrane and the second membrane, and are formed by the edge of the bending region membrane being recessed towards the center.

4. The protective film as described in claim 3, characterized in that, The connection points between the clearance groove and the first membrane, the second membrane, and the edge portion are smoothly transitioned.

5. The protective film as described in claim 1, characterized in that, It also includes an adhesive layer disposed in the cavity formed by the main body and the edge.

6. The protective film as described in claim 1, characterized in that, The thickness of the main body is in the range of 0.02-0.05 mm.

7. The protective film as described in claim 1, characterized in that, The protective film is made of UTG material.

8. The protective film as described in claim 7, characterized in that, The protective film is a tempered glass film.

9. The protective film according to any one of claims 1 to 8, characterized in that, The lower surface of the edge portion is provided with a black edge formed by ink.

10. A method for preparing a protective film, characterized in that, Includes the following steps: Provide single-piece substrates; The outer contour of the substrate is processed to remove excess material from the outer contour; The substrate is thinned in the middle to form a main body in the middle and an edge part at the edge of the main body. The surface of the substrate used to attach to one side of the screen is defined as the lower surface, and the other side surface opposite to the lower surface is defined as the upper surface. The lower surface of the edge part protrudes from the lower surface of the main body.

11. The method for preparing the protective film as described in claim 10, characterized in that, Before processing the outer contour of the substrate, the method further includes: stacking multiple substrates one on top of the other, and bonding and fixing adjacent substrates together with a soluble adhesive.

12. The method for preparing the protective film as described in claim 11, characterized in that, After processing the outer contour of the substrate, the process further includes: dissolving the soluble adhesive between the multiple bonded substrates, separating the multiple fixed substrates into individual substrates, and removing residual adhesive from the surface of the substrates.

13. The method for preparing the protective film as described in claim 10, characterized in that, The step of processing the outer contour of the substrate further includes: processing the two ends of the substrate used to form the bending area membrane to form clearance grooves, wherein the clearance grooves are formed by cutting from the edge of the substrate towards the center.

14. The method for preparing the protective film as described in claim 13, characterized in that, Before thinning the middle part of the substrate, the method further includes: covering the entire upper surface of the substrate with a layer of protective oil, and covering the lower surface of the substrate with a layer of protective oil corresponding to the edge portion.

15. The method for preparing the protective film as described in claim 14, characterized in that, The thinning process of the middle part of the substrate specifically includes: placing the substrate in a hydrofluoric acid solution for etching, so that the thickness of the area of ​​the substrate without protective oil is reduced, thereby forming the main body and the edge.

16. The method for preparing the protective film as described in claim 10, characterized in that, The process further includes: after thinning the middle part of the substrate, the thinned substrate is then tempered.

17. The method for preparing the protective film as described in claim 16, characterized in that, After tempering the thinned substrate, the process further includes: screen printing ink on the lower surface of the edge portion to form a black edge on the edge portion.

18. The method for preparing the protective film as described in claim 17, characterized in that, After screen printing ink on the lower surface of the edge portion, the method further includes: attaching an adhesive layer in the cavity formed by the main body portion and the edge portion, and covering the adhesive layer with a release film.

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