Folding screen protector and preparation process thereof

Abstract

The present invention belongs to the field of ultra-thin glass technology, and specifically relates to a folding screen protector and a preparation process thereof. The folding screen protector provided by the present invention 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 adhesive film layer. The present invention sprays a layer of light-curing coating added with modified silica and methyl propylene cage-type silsesquioxane on PET resin as a functional base film, introduces a rigid group phenyl into the molecular structure of the thermosetting resin film, and uses methyltrimethoxysilane, phenyltrimethoxysilane and 3-glycidyloxypropyltrimethoxysilane as monomers to co-polymerize to obtain highly transparent polysiloxane as OCA glue, which effectively improves the bending performance and impact resistance of the folding screen protector.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-thin glass, and in particular relates to a foldable screen protector and a preparation process thereof. Background Art

[0002] Compared with traditional electronic devices, foldable electronic devices can increase the screen area while maintaining portability. Therefore, foldable electronic devices have received increasing attention in the smart terminal market, which also puts higher technical requirements on foldable display devices.

[0003] Ultra-thin glass (UTG) is used as a flexible cover material in foldable display devices. When the thickness of UTG is reduced to below 50μm, it exhibits excellent bending performance, with the bending radius reduced to less than 1mm, meeting the stringent requirements of flexible screens for extremely small curvature radii. However, as the thickness of UTG decreases, its impact resistance decreases significantly, causing the critical failure height in the drop ball test to drop below 10mm. Although increasing the thickness of UTG can improve its strength, its impact resistance does not significantly improve.

[0004] To improve the impact resistance of UTG, conventional reinforcement is typically achieved using a multi-layer composite structure. 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 example, Chinese patent application publication number CN119445980A discloses a flexible screen cover, a flexible screen, and a foldable electronic device. The flexible screen cover comprises 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 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 for both the first and second surfaces of the ultra-thin glass, thereby enhancing the impact resistance of the ultra-thin glass. The first buffer coating is made of any one or more of an acrylate resin, a silicone resin, an epoxy resin, or a polyurethane resin, while the second buffer coating is made of any one or more of an acrylate-modified polyurethane, an epoxy-modified polyurethane, a hyperbranched polyurethane, an acrylate resin, a silicone resin, or an epoxy resin. While this flexible folding cover can improve the impact resistance of UTG to a certain extent, due to the multiple layers of low-modulus foldable optical adhesive and polyethylene terephthalate film on both sides of the UTG, after a period of use, the folds will develop surface unevenness, delamination, severe creases, or nail marks, affecting the appearance of the screen. Therefore, the development of a folding screen protector with excellent adhesion and functionality has become a development trend in the industry. Summary of the Invention

[0005] In order to solve the technical problems of poor bending and adhesion performance and impact resistance of the foldable screen protector in the prior art, the present invention provides a foldable screen protector and a preparation process thereof.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A folding screen protector 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;

[0008] The preparation method of the functional base film is as follows: (1) fully mixing modified silica and β-hydroxyethyl methacrylate to obtain a mixed solution I; (2) evenly mixing methacrylic cage-type silsesquioxane, acetone and tetrahydrofuran to obtain a mixed solution II; (3) adding mixed solution I, bisphenol A epoxy acrylate and benzophenone to the mixed solution II in a light-proof environment, and obtaining a mixed solution III after ultrasonic treatment; (4) spraying the mixed solution III on the surface of the cleaned PET film, and obtaining the functional base film after curing.

[0009] Through the above technical solution, modified silica and methacrylic cage silsesquioxane are added to a photocurable coating and sprayed onto the surface of the PET film to form a uniform nanocoating. The modified silica has a small particle size, high hardness, and good stability. Its uniform dispersion in the nanocoating can effectively improve the wear resistance and hardness of the functional base film. The methacrylic cage silsesquioxane is a nano-sized organic / inorganic hybrid hollow closed polysiloxane that can be evenly dispersed in the nanocoating and chemically bonded to the organic polymer, increasing the polymer's crosslinking degree and effectively improving the film's toughness, impact resistance, and other mechanical properties. Furthermore, the nanocoating on the surface of the functional base film has a low surface energy and excellent hydrophobicity. Sweat from fingers forms droplets on the surface of the functional base film, thus providing excellent anti-fingerprint properties.

[0010] Furthermore, the preparation method of the modified silica described in the preparation method of the functional base film is: nano-silica is evenly mixed with deionized water to prepare an emulsion with a mass percentage of silica of 14%-17%, and then vinyl tris (β-methoxyethoxy) silane is added after heating to 60-70°C, and stirred and heated to 80-90°C, and the reaction is kept warm for 1-1.5 hours, filtered, and dried to obtain modified silica.

[0011] Through the above technical solution, nano-silica is modified with vinyl tris (β-methoxyethoxy) silane, which not only enables the prepared modified nano-silica to be uniformly dispersed in the functional base film, but also vinyl tris (β-methoxyethoxy) silane can undergo a cross-linking reaction with the organic polymer, thereby improving the cross-linking degree of the nano-coating and effectively fixing the nano-silica, so that the prepared nano-coating has good mechanical properties.

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

[0013] Furthermore, the weight proportions of the components in the preparation method of the functional base film are: 8-12 parts of modified silica, 20-25 parts of β-hydroxyethyl methacrylate, 10-15 parts of methacrylic cage 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.

[0014] Furthermore, the preparation method of the thermosetting resin film is as follows: heating phenyl tris (dimethylsiloxy) silane to 115-120 ° C, adding chloroplatinic acid and then adding glycidyl methacrylate, keeping the temperature for reaction for 3.5-4 hours, cooling, adding bisphenol A type epoxy resin, curing agent and catalyst, stirring and degassing, and then coating it on a release film and curing it to obtain a thermosetting resin film.

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

[0016] Furthermore, the weight proportions of the components in the preparation method of the thermosetting resin film are: 10-13 parts of phenyl tris(dimethylsiloxy)silane, 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; the curing agent is polyetheramine D230, and the catalyst is octylphenol.

[0017] Furthermore, the OCA adhesive film layer is prepared by coating and curing the OCA adhesive. The preparation method of the OCA adhesive is as follows: adding a sulfuric acid aqueous solution and methyltrimethoxysilane with a mass percentage of 75%-85% to a reactor, heating to 70-80°C, and then adding phenyltrimethoxysilane and 3-glycidyloxypropyltrimethoxysilane at the same time under stirring, keeping the temperature for reaction for 4-5 hours, cooling, standing to separate the layers, removing the aqueous phase, and washing the organic phase with deionized water until neutral to obtain the OCA adhesive.

[0018] In the above technical solution, methyltrimethoxysilane, phenyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane are used as monomers for co-polymerization to obtain a highly transparent polysiloxane as the OCA adhesive. 3-glycidyloxypropyltrimethoxysilane 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 can overcome the various stresses to which the folding screen protector is subjected during the bending process, allowing the OCA adhesive to automatically repair minor damage caused by external forces, thereby effectively extending the service life of the folding screen protector. In addition, the above OCA adhesive has good adhesion, effectively preventing delamination caused by external forces.

[0019] Furthermore, the weight proportions of the components in the preparation method of OCA glue are: 20-25 parts of sulfuric acid aqueous solution, 30-40 parts of methyltrimethoxysilane, 10-15 parts of phenyltrimethoxysilane, and 15-20 parts of 3-glycidyloxypropyltrimethoxysilane.

[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 film layer is 35-50 μm.

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

[0022] The present invention also provides a preparation process of the folding screen protector, which is specifically: laminating the functional base film PET with the thermosetting resin film without the release paper, and then laminating UTG, the thermosetting resin film without the release paper, and the OCA adhesive film on the thermosetting resin film in sequence, and laminating and cutting them through a fully automatic hot pressing laminating machine to obtain the folding screen protector.

[0023] Through the above technical solution, the thermosetting resin film is adhered to both sides of the UTG, and then the functional base film is adhered to one side and the OCA film is adhered to the other side. The folding screen protector is prepared by hot pressing. The hot pressing process can effectively avoid debonding between the film layers and effectively improve the service life of the folding screen protector.

[0024] Compared with the prior art, the foldable screen protector and its preparation process provided by the present invention have the following technical advantages:

[0025] (1) The present invention sprays a layer of light-curing coating added with modified silica and methacrylic cage silsesquioxane on 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 group phenyl into the molecular structure of the thermosetting resin film, effectively improving the impact resistance of the bisphenol A epoxy resin;

[0027] (3) The present invention uses methyltrimethoxysilane, phenyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane as monomers to co-polymerize to obtain highly transparent polysiloxane as OCA glue. The epoxy group side chain and phenyl side chain in its molecular structure can effectively enhance the molecular cohesion of the OCA glue, thereby avoiding debonding and stratification of the folding screen protector during the bending process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a picture of the foldable screen protector prepared in Example 3 before being bent;

[0029] Figure 2 This is a picture of the foldable screen protector prepared in Example 3 after being bent under a microscope;

[0030] Figure 3 This is the infrared spectrum of the OCA glue prepared in Example 3. DETAILED DESCRIPTION

[0031] The following will be further described in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Those skilled in the art may make various modifications based on the basic concept of the present invention, but as long as they do not depart from the basic concept of the present invention, they are all within the scope of the present invention.

[0032] The preparation process of the folding screen protector described in this specific embodiment is specifically as follows: the functional base film PET is laminated with the thermosetting resin film without the release paper, and then UTG, the thermosetting resin film without the release paper, and the OCA film are laminated on the thermosetting resin film in sequence, and the lamination and cutting are performed by a fully automatic hot pressing laminating machine to obtain the folding screen protector.

[0033] In this specific embodiment, the molecular weight of the bisphenol A epoxy resin is 500-700, and the degree of polymerization n is less than 2.

[0034] Example 1

[0035] A folding screen protector 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 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) 8 g of modified silica and 20 g of β-hydroxyethyl methacrylate are fully mixed to obtain a mixed solution I; (2) 10 g of methyl propylene cage-type silsesquioxane, 30 g of acetone and 30 g of tetrahydrofuran are evenly mixed to obtain a mixed solution II; (3) mixed solution I, 35 g of bisphenol A epoxy acrylate and 12 g of benzophenone are added to the mixed solution II in a light-proof environment, and mixed solution III is obtained after ultrasonic treatment; (4) mixed solution III is sprayed on the surface of a cleaned PET film (with a thickness of 10 μm), and the functional base film is obtained after curing.

[0037] The modified silica is prepared by uniformly mixing nano-silica and deionized water to prepare an emulsion with a silica mass percentage of 14%, heating the mixture to 60°C, adding vinyl tris(β-methoxyethoxy)silane (5% by mass of the nano-silica), stirring and heating the mixture to 80°C, maintaining the mixture for a reaction of 1 hour, filtering, and drying the mixture to obtain the modified silica.

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

[0039] The OCA adhesive film layer is prepared by coating and curing the OCA adhesive. The preparation method of the OCA adhesive is as follows: 20g of a 75% by mass sulfuric acid aqueous solution and 30g of methyltrimethoxysilane are added to a reactor, the temperature is raised to 70°C, and then 10g of phenyltrimethoxysilane and 15g of 3-glycidoxypropyltrimethoxysilane are added simultaneously under stirring, the reaction is kept warm for 4h, cooled, and allowed to stand for stratification. After removing the aqueous phase, the organic phase is washed with deionized water until neutral to obtain the OCA adhesive.

[0040] Example 2

[0041] A folding screen protector 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 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) 12 g of modified silica and 25 g of β-hydroxyethyl methacrylate are fully mixed to obtain a mixed solution I; (2) 15 g of methyl propylene cage-type silsesquioxane, 40 g of acetone and 40 g of tetrahydrofuran are evenly mixed to obtain a mixed solution II; (3) mixed solution I, 40 g of bisphenol A epoxy acrylate and 15 g of benzophenone are added to the mixed solution II in a light-proof environment, and mixed solution III is obtained after ultrasonic treatment; (4) mixed solution III is sprayed on the surface of a cleaned PET film (with a thickness of 15 μm), and the functional base film is obtained after curing.

[0043] The modified silica is prepared by uniformly mixing nano-silica and deionized water to prepare an emulsion with a silica mass percentage of 17%, heating the mixture to 70°C, adding vinyl tris(β-methoxyethoxy)silane (8% by mass of the nano-silica), stirring and heating the mixture to 90°C, maintaining the mixture for a reaction of 1.5 hours, filtering, and drying to obtain the modified silica.

[0044] The preparation method of the thermosetting resin film is as follows: 13g of phenyl tris (dimethylsiloxy) silane is heated to 120°C, 3g of chloroplatinic acid is added, and then 18g of glycidyl methacrylate is added dropwise within 1 hour, the mixture is kept warm for reaction for 4 hours, and then cooled. 120 parts of bisphenol A epoxy resin, 35g of polyetheramine D230, and 5g of octylphenol are added, and the mixture is stirred and degassed in a vacuum mixer. The mixture is then coated on a release film and cured at 90°C for 4.5 hours to obtain a thermosetting resin film.

[0045] The OCA adhesive film layer is prepared by coating and curing the OCA adhesive. The preparation method of the OCA adhesive is as follows: adding 25g of an 85% by mass sulfuric acid aqueous solution and 40g of methyltrimethoxysilane to a reactor, heating to 80°C, and then adding 15g of phenyltrimethoxysilane and 20g of 3-glycidoxypropyltrimethoxysilane while stirring, keeping the temperature for reaction for 5h, cooling, standing to separate the layers, removing the aqueous phase, and washing the organic phase with deionized water until neutral to obtain the OCA adhesive.

[0046] Example 3

[0047] A folding screen protector 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 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 functional base film is prepared as follows: (1) 10 g of modified silica and 22 g of β-hydroxyethyl methacrylate are fully mixed to obtain a mixed solution I; (2) 12 g of methyl propylene cage-type silsesquioxane, 35 g of acetone and 35 g of tetrahydrofuran are uniformly mixed to obtain a mixed solution II; (3) mixed solution I, 38 g of bisphenol A epoxy acrylate and 14 g of benzophenone are added to the mixed solution II in a light-proof environment, and mixed solution III is obtained after ultrasonic treatment; (4) mixed solution III is sprayed on the surface of a cleaned PET film (with a thickness of 12 μm), and the functional base film is obtained after curing.

[0049] The modified silica is prepared by uniformly mixing nano-silica and deionized water to prepare an emulsion with a silica mass percentage of 15%, heating the mixture to 65° C., adding vinyl tris(β-methoxyethoxy)silane (7% by mass of the nano-silica), stirring and heating the mixture to 85° C., maintaining the mixture for a reaction of 1.2 hours, filtering, and drying the mixture to obtain the modified silica.

[0050] The preparation method of the thermosetting resin film is as follows: 12 g of phenyl tris (dimethylsiloxy) silane is heated to 118° C., 2 g of chloroplatinic acid is added, and then 17 g of glycidyl methacrylate is added dropwise within 1 hour, the mixture is kept warm for reaction for 3.8 hours, cooled, 115 g of bisphenol A epoxy resin, 32 g of polyetheramine D230, and 4 g of octylphenol are added, the mixture is stirred and degassed in a vacuum mixer, and then coated on a release film and cured at 90° C. for 4.5 hours to obtain a thermosetting resin film.

[0051] The OCA adhesive film layer is prepared by coating and curing the OCA adhesive. The preparation method of the OCA adhesive is as follows: 22g of an 80% by mass sulfuric acid aqueous solution and 35g of methyltrimethoxysilane are added to a reactor, the temperature is raised to 75°C, and then 13g of phenyltrimethoxysilane and 18g of 3-glycidoxypropyltrimethoxysilane are added simultaneously under stirring, the reaction is kept warm for 4.5h, cooled, and allowed to stand for stratification. After removing the aqueous phase, the organic phase is washed with deionized water until neutral to obtain the OCA adhesive.

[0052] Comparative Example 1

[0053] 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 an equal amount of acetone is used instead of modified silica in the preparation method of the functional base film in this comparative example.

[0054] Comparative Example 2

[0055] 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 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 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 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 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 the preparation method of the thermosetting resin film in this comparative example is: degassing the bisphenol A type epoxy resin, coating it on the release film, and curing it to obtain a thermosetting resin film.

[0060] Comparative Example 5

[0061] 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 the OCA glue described in this comparative example is prepared according to the preparation method of OCA glue disclosed in Example 3 in the patent application text 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-glycidyloxypropyltrimethoxysilane in the preparation method of the OCA glue 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 glue in this comparative example.

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

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

[0068] Bendability test: The folding screen protector is attached to a bending test machine. The attached surface must be flat, tight, and free of bubbles and wrinkles (Microgram SA6500 mobile phone bending durability tester). If the protective film at the bend of the test machine is deformed, cracked, or warped, the bending test is stopped and the number of bends is recorded. The pictures of the folding screen protector prepared in Example 3 before and after bending under a microscope are shown in Figure 1. Figure 1 and Figure 2 .

[0069] Impact resistance test: A steel ball with a diameter of 20mm and a mass of 32.6g is dropped from different heights onto a folding screen with a folding screen protective film attached. The heights at which broken points and bright points appear are recorded.

[0070] The test was conducted in accordance with ASTM D3363-2005 "Standard Test Method for Determination of Coating Hardness by Pencil Test" using a YASUDA pencil hardness tester with a load of 750g.

[0071] Peeling force of the OCA film layer: The peeling force test of the OCA film layer was performed with reference to JIS Z0237 (300 mm / min, 180°).

[0072] The test 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 frequency of >110,000 times and a ball drop height of ≥2.1 m, which fully demonstrates that the folding screen protector provided by the present invention has good bending and fitting performance and impact resistance.

[0076] Compared with Example 3, in the preparation method of the functional base film of Comparative Example 1, an equal amount of acetone is used instead of modified silica, but the pencil hardness of the folding screen protector prepared is reduced, which shows that the addition of modified silica can effectively improve the hardness of the folding screen protector; in the preparation method of the functional base film of Comparative Example 2, an equal amount of acetone is used instead of methacrylic cage silsesquioxane, but the drop height of the folding screen protector prepared is reduced, which shows that methacrylic cage silsesquioxane can improve the toughness and impact resistance of the folding screen protector; in the preparation method of the functional base film of Comparative Example 3, an equal amount of nano-silica is used instead of modified silica, but the drop height of the folding screen protector prepared is slightly reduced, and the pencil hardness is reduced. , which is due to the uneven dispersion of unmodified silica in the functional base film. The uniform dispersion of silica in the functional base film can improve the impact resistance of the folding screen protector; in Comparative Example 4, the thermosetting resin film is a bisphenol A epoxy resin film, but the drop height of the folding screen protector obtained is significantly reduced, which shows that the process of introducing phenyl groups into the molecular structure of bisphenol A epoxy resin in the present invention can effectively improve the impact resistance of the bisphenol A epoxy resin film; the OCA glue in Comparative Example 5 adopts the OCA glue disclosed in Example 3 of the patent application text with publication number CN118389101A, but the bending number of the folding screen protector obtained is reduced, and the peeling force of the OCA glue film layer is reduced; Comparative Example 6 In the preparation method of OCA glue, methyltrimethoxysilane is used instead of 3-glycidoxypropyltrimethoxysilane. In the preparation method of OCA glue in comparative example 7, methyltrimethoxysilane is used instead of phenyltrimethoxysilane. However, the bending times of the prepared folding screen protector and the peeling force of the OCA film layer are significantly reduced. This shows that the introduction of long side chains and phenyl side chains containing epoxy groups into the molecular structure of OCA glue in the present invention can effectively enhance the cohesion of OCA glue, thereby improving the bending performance of the folding screen protector.

[0077] Depend on Figure 1 It can be seen that the foldable screen protector prepared in Example 3 of the present invention has no obvious creases before being bent. Figure 2 It can be seen that when the folded screen protector is observed under a 50x microscope, no crease appears on the right side of the boundary of the folded screen protector, which indicates that the folded screen protector provided by the present invention has good bending performance.

[0078] Test Example 2: Light transmittance and water drop angle test

[0079] Test sample: folding screen protectors prepared in Examples 1 to 3;

[0080] Light transmittance: Refer to the method for determination of light transmittance and haze of transparent plastics in "GB / T2410-2008" to test the light transmittance of the folding screen protective film.

[0081] Water drop angle test: Use a conventional water drop angle tester to test the surface of the protective film.

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

[0083] Table 2

[0084]

[0085] It can be seen from Table 2 that the foldable screen protector provided by the present invention has good light transmission and hydrophobic effects.

[0086] Test Example 3: Infrared Spectrum Test

[0087] The OCA glue prepared in Example 3 was tested using a Fourier transform infrared spectrometer (FT-IR, Nicolet 5700, Nicolet). The sample preparation method was as follows: the OCA glue was coated on a KBr tablet, dried, and the solidified film was dried, then crushed and directly mixed with KBr powder, and tableted. The test method was: the resolution was 4 cm -1 , the number of scans is 32 times, and the scanning range is 4000cm -1 -500cm -1 , infrared spectrum analysis was performed on OCA glue. The test results are shown in the attached Figure 3 shown.

[0088] Depend on Figure 3 It can be seen that at 1100cm -1 The characteristic absorption peak of Si-O-Si bond appeared at 1259 cm -1 The characteristic absorption peak of Si-CH3 appeared at 1240 cm -1 The characteristic absorption peak of Si-phenyl appeared at 842 cm -1 The bending vibration peak of COC appears at 754 cm -1 The characteristic absorption peak of epoxy group appeared at 2840 cm -1 The stretching vibration peak of CH3 in Si-O-CH3 appears at . Therefore, in the preparation process of the OCA glue of the present invention, methyltrimethoxysilane, phenyltrimethoxysilane and 3-glycidyloxysilane achieve good polycondensation effect.

[0089] The above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Persons skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. Any equivalent modifications or alterations made by persons skilled in the art without departing from the technical spirit of the present invention are intended to fall within the scope of protection 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 film layer; The preparation method of the functional base film is as follows: (1) fully mixing modified silica and β-hydroxyethyl methacrylate to obtain a mixed solution I; (2) evenly mixing methacrylic cage-type silsesquioxane, acetone and tetrahydrofuran to obtain a mixed solution II; (3) adding mixed solution I, bisphenol A epoxy acrylate and benzophenone to the mixed solution II in a light-proof environment, and obtaining a mixed solution III after ultrasonic treatment; (4) spraying the mixed solution III on the surface of the cleaned PET film, and obtaining the functional base film after curing.

2. The foldable screen protector according to claim 1, characterized in that: The modified silica is prepared by uniformly mixing nano-silica and deionized water to prepare an emulsion with a silica mass percentage of 14%-17%, heating the mixture to 60-70°C, adding vinyl tris(β-methoxyethoxy)silane, stirring and heating the mixture to 80-90°C, maintaining the mixture for a reaction of 1-1.5 hours, filtering, and drying to obtain the modified silica.

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

4. The foldable screen protector according to claim 1, characterized in that: The weight proportions of the components in the preparation method of the functional base film are: 8-12 parts of modified silica, 20-25 parts of beta-hydroxyethyl methacrylate, 10-15 parts of methacrylic cage 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 preparation method of the thermosetting resin film comprises: heating phenyl tris (dimethylsiloxy) silane to 115-120° C., adding chloroplatinic acid and then glycidyl methacrylate, keeping the temperature for reaction for 3.5-4 hours, cooling, adding bisphenol A epoxy resin, curing agent and catalyst, stirring and degassing, and then coating on a release film and curing to obtain a thermosetting resin film.

6. The foldable screen protector according to claim 5, characterized in that: The weight proportions of the components in the preparation method of the thermosetting resin film are as follows: 10-13 parts of phenyl tris(dimethylsiloxy)silane, 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; 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 prepared by coating and curing the OCA adhesive. The preparation method of the OCA adhesive is as follows: adding a sulfuric acid aqueous solution and methyltrimethoxysilane with a mass percentage of 75%-85% to a reactor, heating to 70-80°C, and then adding phenyltrimethoxysilane and 3-glycidyloxypropyltrimethoxysilane simultaneously under stirring, keeping the temperature for reaction for 4-5 hours, cooling, standing to separate the layers, removing the aqueous phase, and washing the organic phase with deionized water until neutral to obtain the OCA adhesive.

8. The foldable screen protector according to claim 7, characterized in that: The weight proportions of the components in the preparation method of OCA glue are: 20-25 parts of sulfuric acid aqueous solution, 30-40 parts of methyltrimethoxysilane, 10-15 parts of phenyltrimethoxysilane, and 15-20 parts of 3-glycidyloxypropyltrimethoxysilane.

9. The foldable screen protector according to claim 1, wherein: 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 film layer is 35-50 μm.

10. The process for preparing a foldable screen protector according to any one of claims 1 to 9, characterized in that: Specifically, the functional base film PET is laminated to the thermosetting resin film with the release paper removed, and then UTG, the thermosetting resin film with the release paper removed, and the OCA film are laminated on the thermosetting resin film in sequence. The lamination and cutting are performed using a fully automatic hot pressing laminating machine to obtain a folding screen protector.

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