Foldable screen protector and preparation process therefor

Abstract

The present invention belongs to the technical field of ultra-thin glass, and specifically relates to a foldable screen protector and a preparation process therefor. The foldable screen protector provided by the present invention sequentially comprises, from top to bottom, a functional base film layer, a thermosetting resin film layer, a UTG layer, a thermosetting resin film layer, and an OCA film layer. In the present invention, a layer of photocurable coating, to which a modified silica and acryloxypropyl polysilsesquioxane has been added, is sprayed on a PET resin to act as a functional base film, a rigid phenyl group is introduced into the molecular structure of a thermosetting resin film, and methyltrimethoxysilane, phenyltrimethoxysilane and 3-glycidyloxypropyltrimethoxysilane are used as monomers for co-polymerization to obtain a highly transparent polysiloxane to act as an OCA, thereby effectively improving the bending performance and impact resistance of the foldable screen protector.

Description

A folding screen protection sticker and a preparation process thereof TECHNICAL FIELD

[0001] The present application belongs to the technical field of ultra-thin glass and specifically relates to a folding screen protection sticker and a preparation process thereof. BACKGROUND

[0002] Compared with traditional electronic devices, foldable electronic devices can improve a larger screen area while maintaining portability, and therefore, foldable electronic devices have received more and more attention in the intelligent terminal market, which also puts forward higher technical requirements for foldable display devices.

[0003] In the field of foldable display devices, ultra-thin glass (UTG) is used as a flexible cover material. When the thickness of the UTG is reduced to below 50 pm, it exhibits excellent bending performance, and the bending radius can be reduced to below 1 mm, meeting the stringent requirements of flexible screens for extremely small curvature radii. However, when the thickness of the UTG is thinned, its impact resistance significantly decreases, resulting in a critical breakage height in the drop ball test being reduced to below 10 mm. Although increasing the thickness of the UTG can improve its strength, its impact resistance does not significantly improve.

[0004] In existing technologies, to improve the impact resistance of UTG (Ultra-Thin Glass), a multi-layer composite structure is typically used for reinforcement. For example, a layer of hardened polyimide (CPI) or polyethylene terephthalate (PET) film is bonded to the UTG surface using foldable optical adhesive (OCA) to form a laminated structure. For instance, Chinese patent application CN119445980A discloses a flexible screen cover, a flexible screen, and a foldable electronic device. This flexible screen cover includes ultra-thin glass, a first buffer coating, and a second buffer coating. The ultra-thin glass has a first surface and a second surface disposed opposite to each other. The first buffer coating is disposed on the first surface, and the second buffer coating is disposed on the second surface. The first and second buffer coatings provide physical protection to both the first and second surfaces of the ultra-thin glass, improving its impact resistance. The material of the first buffer coating includes any one or more of acrylate resin, silicone resin, epoxy resin, and polyurethane resin. The material of the second buffer coating includes any one or more of acrylate-modified polyurethane, epoxy-modified polyurethane, hyperbranched polyurethane, acrylic resin, silicone resin, and epoxy resin. However, while this type of flexible folding cover can improve the impact resistance of UTG to some extent, the presence of multiple layers of low-modulus foldable optical adhesive and polyethylene terephthalate film on both sides of the UTG leads to unevenness, delamination, severe creases, or fingernail marks at the folding area after a period of use, affecting the screen's appearance. Therefore, developing a foldable screen protector with good fit and functionality has become a trend in the industry. Summary of the Invention

[0005] To address the technical problems of poor bending adhesion and impact resistance in existing foldable screen protectors, this invention provides a foldable screen protector and its manufacturing process.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A foldable screen protector, from top to bottom, comprises a functional base film layer, a thermosetting resin film layer, a UTG layer, another thermosetting resin film layer, and an OCA adhesive film layer.

[0008] The preparation method of the functional base film is as follows: (1) Mix modified silica with β-hydroxyethyl methacrylate to obtain mixture I; (2) Mix methacrylamide cage silsesquioxane, acetone and tetrahydrofuran evenly to obtain mixture II; (3) Add mixture I, bisphenol A epoxy acrylate and benzophenone to mixture II under light-protected environment, and obtain mixture III after ultrasonication; (4) Spray mixture III onto the surface of a cleaned PET film, and obtain the functional base film after curing.

[0009] The above technical solution involves incorporating modified silica and methacryloyl cage-like silsesquioxane into a photocurable coating. A uniform nano-coating is then formed on the surface of a PET film via spraying. Modified silica, characterized by its small particle size, high hardness, and good stability, effectively improves the wear resistance and hardness of the functional base film when uniformly dispersed within the nano-coating. Methacryloyl cage-like silsesquioxane, a nano-sized organic / inorganic hybrid hollow closed-cell polysiloxane, can be uniformly dispersed within the nano-coating and chemically bonded to the organic polymer, increasing the polymer's cross-linking degree and thus effectively enhancing the film's toughness, impact resistance, and other mechanical properties. Furthermore, the nano-coating on the functional base film surface has low surface energy and good hydrophobicity; sweat from fingers forms droplets on the functional base film surface, resulting in excellent fingerprint resistance.

[0010] Furthermore, the modified silica preparation method described in the preparation method of the functional base film is as follows: nano silica and deionized water are mixed evenly to prepare an emulsion with a silica mass percentage of 14%-17%. After heating to 60-70℃, vinyltris(β-methoxyethoxy)silane is added, stirred and heated to 80-90℃, and kept at this temperature for 1-1.5 hours. After filtration and drying, modified silica is obtained.

[0011] By using the above technical solution, the modification of nano-silica with vinyltris(β-methoxyethoxy)silane can not only enable the modified nano-silica to be uniformly dispersed in the functional base film, but also allow vinyltris(β-methoxyethoxy)silane to undergo cross-linking reaction with organic polymers. This not only improves the cross-linking degree of the nano-coating, but also effectively fixes the nano-silica, giving the prepared nano-coating good mechanical properties.

[0012] Furthermore, in the method for preparing modified silica, the mass of vinyltris(β-methoxyethoxy)silane is 5%-8% of the mass of nano-silica.

[0013] Furthermore, the weight proportions of each component in the preparation method of the functional base film are as follows: 8-12 parts modified silica, 20-25 parts β-hydroxyethyl methacrylate, 10-15 parts methacryloyl cage-type silsesquioxane, 30-40 parts acetone, 30-40 parts tetrahydrofuran, 35-40 parts bisphenol A epoxy acrylate, and 12-15 parts benzophenone.

[0014] Furthermore, the preparation method of the thermosetting resin film is as follows: phenyltris(dimethylsiloxane)silane is heated to 115-120℃, chloroplatinic acid is added, followed by glycidyl methacrylate, and the reaction is maintained at this temperature for 3.5-4 hours. After cooling, bisphenol A type epoxy resin, curing agent, and catalyst are added, and the mixture is stirred to remove bubbles. Then, it is coated onto a release film and cured to obtain a thermosetting resin film.

[0015] Through the above technical solution, phenyltris(dimethylsiloxane)silane undergoes an addition reaction with glycidyl methacrylate, and then reacts with bisphenol A epoxy resin, introducing the rigid phenyl group on phenyltris(dimethylsiloxane)silane into the molecule of bisphenol A epoxy resin, thereby effectively improving the impact resistance of bisphenol A epoxy resin.

[0016] Furthermore, in the preparation method of the thermosetting resin film, the weight parts of each component are as follows: 10-13 parts of phenyltris(dimethylsiloxane), 1-3 parts of chloroplatinic acid, 15-18 parts of glycidyl methacrylate, 100-120 parts of bisphenol A epoxy resin, 30-35 parts of curing agent, and 3-5 parts of catalyst; wherein the curing agent is polyetheramine D230, and the catalyst is octylphenol.

[0017] Furthermore, the OCA adhesive film layer is obtained by coating and curing OCA adhesive. The preparation method of the OCA adhesive is as follows: add a sulfuric acid aqueous solution with a mass percentage of 75%-85% and methyltrimethoxysilane to a reaction vessel, heat to 70-80℃, and then simultaneously add phenyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane while stirring. Keep the reaction at this temperature for 4-5 hours, cool, allow to stand and separate into layers, remove the aqueous phase, and wash the organic phase with deionized water until neutral to obtain the OCA adhesive.

[0018] In the above technical solution, methyltrimethoxysilane, phenyltrimethoxysilane, and 3-glycidyl etheroxypropyltrimethoxysilane are used as monomers to co-polymerize and obtain a highly transparent polysiloxane as the OCA adhesive. 3-glycidyl etheroxypropyltrimethoxysilane can introduce long side chains containing epoxy groups into the molecular structure of the OCA adhesive, and phenyltrimethoxysilane can introduce phenyl side chains into the molecular structure of the OCA adhesive, thereby enhancing the molecular cohesion of the OCA adhesive. This overcomes the various stresses experienced by the screen protector during bending, enabling the OCA adhesive to automatically repair minor damage caused by external forces, thus effectively improving the lifespan of the screen protector. Furthermore, the aforementioned OCA adhesive has good adhesion, effectively preventing delamination caused by external forces.

[0019] Furthermore, the weight proportions of each component in the preparation method of OCA adhesive are as follows: 20-25 parts of sulfuric acid aqueous solution, 30-40 parts of methyltrimethoxysilane, 10-15 parts of phenyltrimethoxysilane, and 15-20 parts of 3-glycidyl ether oxypropyltrimethoxysilane.

[0020] Furthermore, the thickness of the functional base film layer is 38-50 μm, the thickness of the thermosetting resin film layer is 40-50 μm, the thickness of the UTG layer is 30-40 μm, and the thickness of the OCA adhesive film layer is 35-50 μm.

[0021] During the research process, this invention discovered that the OCA adhesive layer is a key factor affecting the adhesion performance of foldable screen protectors. When the OCA adhesive layer is too thin, the adhesion performance of the foldable screen protector is poor, and the protector is prone to peeling off and forming creases. Conversely, when the OCA adhesive layer is too thick, it leads to increased light scattering and absorption, thereby reducing the light transmittance of the foldable screen protector and affecting the display effect. When the OCA adhesive layer is within the range provided by this invention, the force per unit length of the adhesive layer is reduced when the foldable screen protector is bent, and the adhesive layer strain is reduced, effectively preventing the adhesive layer from peeling off and forming creases.

[0022] The present invention also provides a manufacturing process for the foldable screen protector, specifically: a functional base film PET is laminated with a thermosetting resin film with the release paper removed, and then UTG, a thermosetting resin film with the release paper removed, and an OCA adhesive film are sequentially laminated onto the thermosetting resin film. The lamination is performed by a fully automatic hot press laminating machine, and the film is then cut to obtain the foldable screen protector.

[0023] The above technical solution involves bonding a thermosetting resin film to both sides of a UTG, then bonding a functional base film to one side and an OCA adhesive film to the other side. The foldable screen protector is then prepared by hot pressing. The hot pressing process can effectively prevent delamination between the film layers and effectively improve the service life of the foldable screen protector.

[0024] Compared with existing technologies, the foldable screen protector and its manufacturing process provided by this invention have the following technical advantages:

[0025] (1) The present invention sprays a layer of light-curing coating containing modified silica and methacrylic cage silsesquioxane onto PET resin to form a uniform nano-coating, which can not only effectively improve the impact resistance of the functional base film, but also give the functional base film a good anti-fingerprint effect.

[0026] (2) The present invention introduces a rigid phenyl group into the molecular structure of the thermosetting resin film, which effectively improves the impact resistance of bisphenol A type epoxy resin.

[0027] (3) In this invention, methyltrimethoxysilane, phenyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane are used as monomers to co-polymerize and obtain a highly transparent polysiloxane as an OCA adhesive. The epoxy group long side chain and phenyl side chain in its molecular structure can effectively enhance the molecular cohesion of the OCA adhesive, thereby avoiding the phenomenon of delamination during the bending process of the folding screen protector. Attached Figure Description

[0028] Figure 1 is a picture of the foldable screen protector prepared in Example 3 before it is bent.

[0029] Figure 2 is a microscopic image of the foldable screen protector prepared in Example 3 after it has been bent.

[0030] Figure 3 shows the infrared spectrum of the OCA adhesive prepared in Example 3. Embodiments of the present invention

[0031] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments. Those skilled in the art can make various modifications based on the fundamental principles of the present invention, but all modifications that do not depart from the fundamental principles of the present invention are within its scope.

[0032] The specific manufacturing process of the foldable screen protector described in this embodiment is as follows: a functional base film PET is laminated with a thermosetting resin film with the release paper removed, and then UTG, a thermosetting resin film with the release paper removed, and an OCA adhesive film are laminated sequentially on the thermosetting resin film. The lamination is performed by a fully automatic hot press laminating machine, and the film is then cut to obtain the foldable screen protector.

[0033] The bisphenol A type epoxy resin described in this specific embodiment has a molecular weight of 500-700 and a degree of polymerization n < 2.

[0034] Example 1

[0035] A foldable screen protector comprises, from top to bottom, a functional base film layer, a thermosetting resin film layer, a UTG layer, another thermosetting resin film layer, and an OCA adhesive film layer; the thickness of the functional base film layer is 38 μm, the thickness of the thermosetting resin film layer is 40 μm, the thickness of the UTG layer is 30 μm, and the thickness of the OCA adhesive film layer is 35 μm.

[0036] The preparation method of the functional base film is as follows: (1) 8g of modified silica and 20g of β-hydroxyethyl methacrylate are thoroughly mixed to obtain mixture I; (2) 10g of methacryloyl cage silsesquioxane, 30g of acetone and 30g of tetrahydrofuran are mixed evenly to obtain mixture II; (3) Mixture I, 35g of bisphenol A epoxy acrylate and 12g of benzophenone are added to mixture II under light-protected environment, and mixture III is obtained after ultrasonication; (4) Mixture III is sprayed on the surface of a cleaned PET film (thickness is 10μm), and functional base film is obtained after curing.

[0037] The modified silica is prepared by mixing nano-silica with deionized water to form an emulsion with a silica mass percentage of 14%. After heating to 60°C, 5% vinyltris(β-methoxyethoxy)silane of nano-silica mass is added, and the mixture is stirred and heated to 80°C. The mixture is kept warm for 1 hour, filtered, and dried to obtain modified silica.

[0038] The thermosetting resin film is prepared as follows: 10g of phenyltris(dimethylsiloxane)silane is heated to 115°C, 1g of chloroplatinic acid is added, and then 15g of glycidyl methacrylate is added dropwise over 1 hour. The mixture is kept at this temperature for 3.5 hours, cooled, and then 100g of bisphenol A epoxy resin, 30g of polyetheramine D230, and 3g of octylphenol are added. After stirring, the mixture is degassed in a vacuum mixer and then coated onto a release film. The film is cured at 90°C for 4.5 hours to obtain the thermosetting resin film.

[0039] The OCA adhesive film layer is obtained by coating and curing OCA adhesive. The preparation method of OCA adhesive is as follows: 20g of 75% sulfuric acid aqueous solution and 30g of methyltrimethoxysilane are added to the reaction vessel, the temperature is raised to 70°C, and then 10g of phenyltrimethoxysilane and 15g of 3-glycidyl etheroxypropyltrimethoxysilane are added simultaneously under stirring. The reaction is kept at the temperature for 4 hours, cooled, allowed to stand and separate into layers, the aqueous phase is removed, and the organic phase is washed with deionized water until neutral to obtain OCA adhesive.

[0040] Example 2

[0041] A foldable screen protector comprises, from top to bottom, a functional base film layer, a thermosetting resin film layer, a UTG layer, another thermosetting resin film layer, and an OCA adhesive film layer; the thickness of the functional base film layer is 50 μm, the thickness of the thermosetting resin film layer is 50 μm, the thickness of the UTG layer is 40 μm, and the thickness of the OCA adhesive film layer is 50 μm.

[0042] The preparation method of the functional base film is as follows: (1) 12g of modified silica and 25g of β-hydroxyethyl methacrylate are thoroughly mixed to obtain mixture I; (2) 15g of methacryloyl cage silsesquioxane, 40g of acetone and 40g of tetrahydrofuran are mixed evenly to obtain mixture II; (3) Mixture I, 40g of bisphenol A epoxy acrylate and 15g of benzophenone are added to mixture II under light-protected environment, and the mixture is ultrasonicated to obtain mixture III; (4) Mixture III is sprayed on the surface of a cleaned PET film (thickness is 15μm), and the functional base film is obtained after curing.

[0043] The modified silica is prepared by mixing nano-silica with deionized water to form an emulsion with a silica mass percentage of 17%. After heating to 70°C, vinyltris(β-methoxyethoxy)silane with a mass of 8% of nano-silica is added. The mixture is stirred and heated to 90°C, and kept at this temperature for 1.5 hours. After filtration and drying, the modified silica is obtained.

[0044] The thermosetting resin film is prepared as follows: 13g of phenyltris(dimethylsiloxane)silane is heated to 120°C, 3g of chloroplatinic acid is added, and then 18g of glycidyl methacrylate is added dropwise over 1 hour. The mixture is kept at this temperature for 4 hours, cooled, and then 120 parts of bisphenol A epoxy resin, 35g of polyetheramine D230, and 5g of octylphenol are added. After stirring, the mixture is degassed in a vacuum mixer and then coated onto a release film. The film is cured at 90°C for 4.5 hours to obtain the thermosetting resin film.

[0045] The OCA adhesive film layer is obtained by coating and curing OCA adhesive. The preparation method of OCA adhesive is as follows: 25g of sulfuric acid aqueous solution with a mass percentage of 85% and 40g of methyltrimethoxysilane are added to the reaction vessel, the temperature is raised to 80℃, and then 15g of phenyltrimethoxysilane and 20g of 3-glycidyl etheroxypropyltrimethoxysilane are added simultaneously under stirring. The reaction is kept at the temperature for 5h, cooled, allowed to stand and separate into layers, the aqueous phase is removed, and the organic phase is washed with deionized water until neutral to obtain OCA adhesive.

[0046] Example 3

[0047] A foldable screen protector comprises, from top to bottom, a functional base film layer, a thermosetting resin film layer, a UTG layer, another thermosetting resin film layer, and an OCA adhesive film layer; the thickness of the functional base film layer is 38 μm, the thickness of the thermosetting resin film layer is 40 μm, the thickness of the UTG layer is 40 μm, and the thickness of the OCA adhesive film layer is 50 μm.

[0048] The preparation method of the functional base film is as follows: (1) 10g of modified silica and 22g of β-hydroxyethyl methacrylate are thoroughly mixed to obtain mixture I; (2) 12g of methacryloyl cage silsesquioxane, 35g of acetone and 35g of tetrahydrofuran are mixed evenly to obtain mixture II; (3) Mixture I, 38g of bisphenol A epoxy acrylate and 14g of benzophenone are added to mixture II under light-protected environment, and the mixture is ultrasonicated to obtain mixture III; (4) Mixture III is sprayed onto the surface of a cleaned PET film (thickness is 12μm), and the functional base film is obtained after curing.

[0049] The modified silica is prepared by mixing nano-silica with deionized water to form an emulsion with a silica mass percentage of 15%. After heating to 65°C, vinyltris(β-methoxyethoxy)silane with a mass of 7% of nano-silica is added. The mixture is stirred and heated to 85°C, and kept at this temperature for 1.2 hours. After filtration and drying, the modified silica is obtained.

[0050] The thermosetting resin film is prepared as follows: 12g of phenyltris(dimethylsiloxane)silane is heated to 118°C, 2g of chloroplatinic acid is added, and then 17g of glycidyl methacrylate is added dropwise over 1 hour. The mixture is kept at this temperature for 3.8 hours, cooled, and then 115g of bisphenol A epoxy resin, 32g of polyetheramine D230, and 4g of octylphenol are added. After stirring, the mixture is degassed in a vacuum mixer and then coated onto a release film. The film is cured at 90°C for 4.5 hours to obtain the thermosetting resin film.

[0051] The OCA adhesive film layer is obtained by coating and curing OCA adhesive. The preparation method of OCA adhesive is as follows: 22g of sulfuric acid aqueous solution with a mass percentage of 80% and 35g of methyltrimethoxysilane are added to the reaction vessel, the temperature is raised to 75°C, and then 13g of phenyltrimethoxysilane and 18g of 3-glycidyl etheroxypropyltrimethoxysilane are added simultaneously under stirring. The reaction is kept at the temperature for 4.5h, cooled, allowed to stand and separate into layers, the aqueous phase is removed, and the organic phase is washed with deionized water until neutral to obtain OCA adhesive.

[0052] Comparative Example 1

[0053] The foldable screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of acetone is used instead of modified silicon dioxide in the preparation method of the functional base film in this comparative example.

[0054] Comparative Example 2

[0055] The foldable screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of acetone is used instead of methacrylic cage silsesquioxane in the preparation method of the functional base film in this comparative example.

[0056] Comparative Example 3

[0057] The foldable screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that an equal amount of nano-silica is used instead of modified silica in the preparation method of the functional base film in this comparative example.

[0058] Comparative Example 4

[0059] The foldable screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the thermosetting resin film in this comparative example is prepared by degassing bisphenol A epoxy resin and coating it onto a release film, followed by curing to obtain the thermosetting resin film.

[0060] Comparative Example 5

[0061] The foldable screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that the OCA adhesive described in this comparative example is prepared according to the OCA adhesive preparation method disclosed in Example 3 of the patent application with publication number CN118389101A.

[0062] Comparative Example 6

[0063] The folding screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that methyltrimethoxysilane is used instead of 3-glycidyl etheroxypropyltrimethoxysilane in the preparation method of the OCA adhesive in this comparative example.

[0064] Comparative Example 7

[0065] The folding screen protector described in this comparative example is similar to that in Example 3. The difference between this comparative example and Example 3 is that methyltrimethoxysilane is used instead of phenyltrimethoxysilane in the preparation method of the OCA adhesive in this comparative example.

[0066] Test Example 1: Bending Performance and Impact Resistance Test

[0067] Test samples: Foldable screen protectors prepared in Examples 1-3 and Comparative Examples 1-7.

[0068] Bending test: The foldable screen protector is attached to a bending test machine. The attachment surface must be flat, tight, and free of bubbles and wrinkles (Microgram SA6500 mobile phone bending durability tester). If the protective film at the bending point of the test machine shows deformation, cracking, or peeling, the bending test is stopped, and the number of bends is recorded. Figures 1 and 2 show microscopic images of the foldable screen protector prepared in Example 3 before and after bending.

[0069] Impact resistance test: A steel ball with a diameter of 20mm and a mass of 32.6g was dropped freely from different heights onto the foldable screen with the protective film attached, and the height at which the breakage or bright spots appeared was recorded.

[0070] The test was conducted according to ASTM D3363-2005, "Standard Test Method for Determination of Hardness of Coatings by Pencil Test". A YASUDA pencil hardness tester with a load of 750g was used to test the pencil hardness of the surface of the protective film.

[0071] Peel strength of OCA film layer: The peel strength of OCA film layer was tested according to JISZ0237 (300 mm / min, 180°).

[0072] The experimental results are shown in Table 1.

[0073] Table 1 Performance Test Results

[0074]

[0075] As shown in Table 1, the folding screen protector provided by the present invention has a bending cycle of >110,000 times and a drop height of ≥2.1m, which fully demonstrates that the folding screen protector provided by the present invention has good bending and bonding performance and impact resistance.

[0076] Compared to Example 3, in Comparative Example 1, an equal amount of acetone was used instead of modified silica in the preparation method of the functional base film, but the pencil hardness of the resulting foldable screen protector was reduced, indicating that the addition of modified silica can effectively improve the hardness of the foldable screen protector. In Comparative Example 2, an equal amount of acetone was used instead of methacryloyl cage-like silsesquioxane in the preparation method of the functional base film, but the drop height of the resulting foldable screen protector was reduced, indicating that methacryloyl cage-like silsesquioxane can improve the toughness and impact resistance of the foldable screen protector. In Comparative Example 3, an equal amount of nano-silica was used instead of modified silica in the preparation method of the functional base film, but the drop height of the resulting foldable screen protector was slightly reduced, and the pencil hardness was also reduced. This is due to the uneven dispersion of unmodified silica in the functional base film. Uniform dispersion of silica in the functional base film can improve the impact resistance of the foldable screen protector. In Comparative Example 4, the thermosetting resin film is a bisphenol A type epoxy resin film, but the drop height of the resulting foldable screen protector is significantly reduced. This indicates that the process of introducing phenyl groups into the molecular structure of the bisphenol A type epoxy resin in this invention can effectively improve the impact resistance of the bisphenol A type epoxy resin film. In Comparative Example 5, the OCA adhesive used is the OCA adhesive disclosed in Example 3 of the patent application with publication number CN118389101A, but the bending times of the resulting foldable screen protector are reduced, and the peel force of the OCA adhesive film layer is reduced. Comparative Example 6... In the preparation method of OCA adhesive, methyltrimethoxysilane is used instead of 3-glycidyl etheroxypropyltrimethoxysilane. In the preparation method of OCA adhesive in Comparative Example 7, methyltrimethoxysilane is used instead of phenyltrimethoxysilane. However, the bending number and peel force of the OCA adhesive film layer of the resulting folding screen protector are significantly reduced. This indicates that the introduction of long side chains containing epoxy groups and phenyl side chains into the molecular structure of OCA adhesive in this invention can effectively improve the cohesive force of OCA adhesive, thereby improving the bending performance of the folding screen protector.

[0077] As shown in Figure 1, the foldable screen protector prepared in Embodiment 3 of the present invention has no obvious creases before bending. As shown in Figure 2, when the screen protector is observed under a 50x microscope after folding, no creases appear on the right side of the boundary of the foldable screen protector. This indicates that the foldable screen protector provided by the present invention has good bending performance.

[0078] Experimental Example 2: Transmittance and Water Droplet Angle Test

[0079] Test samples: Foldable screen protectors prepared in Examples 1-3;

[0080] Light transmittance: The light transmittance of the foldable screen protective film was tested according to the method in GB / T2410-2008 for the determination of light transmittance and haze of transparent plastics.

[0081] Water droplet angle test: The surface of the protective film is tested using a conventional water droplet angle tester.

[0082] The test results are shown in Table 2.

[0083] Table 2

[0084]

[0085] As shown in Table 2, the foldable screen protector provided by the present invention has good light transmission and hydrophobic effects.

[0086] Experimental Example 3: Infrared Spectroscopy Test

[0087] The OCA adhesive prepared in Example 3 was tested using a Fourier transform infrared spectroscopy (FT-IR, Nicolet 5700, Nicolet Corporation). The sample preparation method was as follows: the OCA adhesive was coated onto a KBr pellet, dried, and after the cured film dried, it was pulverized and directly mixed with KBr powder until homogeneous, then pelletized. The testing method was as follows: resolution 4 cm⁻¹. -1 The number of scans was 32, and the scanning range was 4000cm. -1 -500cm -1 Infrared spectroscopy analysis was performed on the OCA adhesive. The test results are shown in Figure 3.

[0088] As shown in Figure 3, at 1100cm -1 The characteristic absorption peak of the silicon-oxygen bond Si-O-Si appeared at 1259 cm⁻¹. -1 The characteristic absorption peak of Si-CH3 appeared at 1240 cm⁻¹. -1 The characteristic absorption peak of Si-phenyl appeared at 842 cm⁻¹. -1 A bending vibration peak of COC appeared at 754 cm⁻¹. -1 The characteristic absorption peak of the epoxy group appeared at 2840 cm⁻¹. -1 A stretching vibration peak of CH3 in Si-O-CH3 was observed. Therefore, methyltrimethoxysilane, phenyltrimethoxysilane, and 3-glycidyl ether oxysilane achieved good polycondensation effect during the preparation of the OCA adhesive of this invention.

[0089] The above embodiments are merely illustrative of the present invention and are not intended to limit the invention. Those skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. All equivalent modifications or alterations made by those skilled in the art without departing from the technical concept of the present invention are still within the protection scope of the present invention.

Claims

1. A foldable screen protector, characterized in that, From top to bottom, it includes a functional base film layer, a thermosetting resin film layer, a UTG layer, a thermosetting resin film layer, and an OCA adhesive film layer. The preparation method of the functional base film is as follows: (1) Mix modified silica with β-hydroxyethyl methacrylate to obtain mixture I; (2) Mix methacrylamide cage silsesquioxane, acetone and tetrahydrofuran evenly to obtain mixture II; (3) Add mixture I, bisphenol A epoxy acrylate and benzophenone to mixture II under light-protected environment, and obtain mixture III after ultrasonication; (4) Spray mixture III onto the surface of a cleaned PET film, and obtain the functional base film after curing.

2. The foldable screen protector according to claim 1, characterized in that, The modified silica is prepared by mixing nano silica with deionized water to form an emulsion with a silica mass percentage of 14%-17%. After heating to 60-70°C, vinyltris(β-methoxyethoxy)silane is added, stirred and heated to 80-90°C, and kept at this temperature for 1-1.5 hours. The mixture is then filtered and dried to obtain the modified silica.

3. The foldable screen protector according to claim 2, characterized in that, The mass of the vinyltris(β-methoxyethoxy)silane is 5%-8% of the mass of nano-silica.

4. The foldable screen protector according to claim 1, characterized in that, The weight proportions of each component in the preparation method of the functional base film are as follows: 8-12 parts of modified silica, 20-25 parts of β-hydroxyethyl methacrylate, 10-15 parts of methacryloyl cage-type silsesquioxane, 30-40 parts of acetone, 30-40 parts of tetrahydrofuran, 35-40 parts of bisphenol A epoxy acrylate, and 12-15 parts of benzophenone.

5. The foldable screen protector according to claim 1, characterized in that, The thermosetting resin film is prepared by heating phenyltris(dimethylsiloxane)silane to 115-120℃, adding chloroplatinic acid, then adding glycidyl methacrylate, keeping it at the temperature for 3.5-4 hours, cooling, adding bisphenol A type epoxy resin, curing agent and catalyst, stirring and degassing, then coating it onto a release film and curing it to obtain a thermosetting resin film.

6. The foldable screen protector according to claim 5, characterized in that, The weight proportions of each component in the preparation method of the thermosetting resin film are as follows: 10-13 parts of phenyltris(dimethylsiloxane), 1-3 parts of chloroplatinic acid, 15-18 parts of glycidyl methacrylate, 100-120 parts of bisphenol A epoxy resin, 30-35 parts of curing agent, and 3-5 parts of catalyst; wherein the curing agent is polyetheramine D230 and the catalyst is octylphenol.

7. The foldable screen protector according to claim 1, characterized in that, The OCA adhesive film layer is obtained by coating and curing OCA adhesive. The preparation method of OCA adhesive is as follows: add 75%-85% sulfuric acid aqueous solution and methyltrimethoxysilane by mass to the reaction vessel, heat to 70-80℃, and then add phenyltrimethoxysilane and 3-glycidyl etheroxypropyltrimethoxysilane while stirring. Keep the reaction at the temperature for 4-5 hours, cool, let stand and separate into layers, remove the aqueous phase and wash the organic phase with deionized water until neutral to obtain OCA adhesive.

8. The foldable screen protector according to claim 7, characterized in that, The weight proportions of each component in the preparation method of OCA adhesive are as follows: 20-25 parts of sulfuric acid aqueous solution, 30-40 parts of methyltrimethoxysilane, 10-15 parts of phenyltrimethoxysilane, and 15-20 parts of 3-glycidyl ether oxypropyltrimethoxysilane.

9. The foldable screen protector according to claim 1, characterized in that, The thickness of the functional base film layer is 38-50 μm, the thickness of the thermosetting resin film layer is 40-50 μm, the thickness of the UTG layer is 30-40 μm, and the thickness of the OCA adhesive film layer is 35-50 μm.

10. The manufacturing process of the foldable screen protector according to any one of claims 1-9, characterized in that, Specifically, the process involves laminating a functional base film PET with a thermosetting resin film (with release paper removed), then sequentially laminating a UTG film, a thermosetting resin film (with release paper removed), and an OCA adhesive film onto the thermosetting resin film. The lamination is then performed using a fully automatic hot press laminating machine, followed by cutting to obtain a foldable screen protector.

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