Composite glass protection paste for flexible folding screen and preparation method of composite glass protection paste

Abstract

The invention relates to the technical field of protective films, and particularly discloses a composite glass protective paste for a flexible folding screen and a preparation method of the composite glass protective paste. The composite glass protection paste for the flexible folding screen sequentially comprises a functional base film, a first thermosetting polymer film, a UTG ultrathin glass layer, a second thermosetting polymer film and an OCA adhesive layer from top to bottom, the preparation method of the OCA adhesive layer comprises the following steps: carrying out activating treatment on nano silicon dioxide particles to obtain modified particles with cations on the surfaces; carrying out reaction on the modified particles and molten hydroxy acrylic resin under the ultrasonic action, and carrying out extrusion granulation to obtain elastic acrylic master batches; uniformly mixing the elastic acrylic master batch with a cross-linking agent and a photoinitiator to obtain the acrylic OCA; and coating OCA on one surface of the release film, and performing ultraviolet curing to obtain an OCA layer. According to the composite glass protection paste for the flexible folding screen, the bending resistance of the protection paste is improved.

Description

Technical Field

[0001] This application relates to the technical field of protective films, and more specifically, it relates to a composite glass protective sticker for flexible folding screens and a preparation method thereof. Background Art

[0002] With the development of science and technology, the usage of folding screens is continuously increasing, and the demand for corresponding protective stickers is also gradually increasing. Currently, ultra-thin glass (UTG) is widely used as a flexible protective film in the field of foldable display devices. When the thickness of UTG is reduced to less than 50 μm, it exhibits excellent bending performance, and the bending radius can be reduced to less than 1 mm, meeting the stringent requirements of flexible screens for extremely small curvature radii. However, the mechanical properties of UTG are negatively correlated with its thickness: as the thickness decreases, its impact resistance significantly decreases, resulting in a critical failure height of usually less than 10 mm in the pen-drop test (simulating drops or collisions in daily use), and there is a high risk of crack propagation. (For folding tablets and folding computers, the UTG thickness is below 150 μm, and the strength increases with the increase in thickness, but the pen-drop performance still does not improve significantly). Such reliability defects severely restrict the large-scale application of UTG in scenarios such as mobile terminals. To improve the impact resistance of UTG, existing technologies mostly use multi-layer composite structures for enhancement.

[0003] The patent application document with the publication number CN118580797A discloses a bend-resistant protective film for folding screens, its preparation method, and application. The bend-resistant protective film for folding screens sequentially includes a release isolation layer, an OCA optical adhesive layer, a flexible bending layer, a silicone layer, and a protective film layer. Although this flexible folding protective film improves the impact resistance of the protective film to a certain extent, due to the presence of the OCA adhesive layer, and the OCA optical adhesive has a low elastic modulus and is difficult to fully release the applied stress, these residual stresses will cause defects such as stress corrosion, delamination, cracking, and fatigue in the protective sticker, ultimately reducing the bend resistance of the protective sticker. Summary of the Invention

[0004] To improve the bend resistance of the prepared protective sticker, this application provides a composite glass protective sticker for flexible folding screens and a preparation method thereof.

[0005] In the first aspect, this application provides a composite glass protective sticker for flexible folding screens, adopting the following technical solution, A composite glass protective sticker for flexible folding screens, sequentially including a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom; The preparation method of the OCA adhesive layer includes the following steps: The nano-silica particles are activated to obtain modified particles with cations on the surface; The modified particles with a mass ratio of 1:1 - 3 and the molten hydroxy acrylic resin react under the ultrasonic action of 600 - 1000W and are extruded and granulated to obtain an elastic acrylic masterbatch; The elastic acrylic masterbatch is uniformly mixed with a crosslinking agent and a photoinitiator to obtain an acrylic OCA optical adhesive; The OCA optical adhesive is coated on one side of the release film and cured by ultraviolet light to obtain an OCA adhesive layer.

[0006] By adopting the above technical solution, the present application has developed a new UTG protection film structure, that is, a thermosetting resin film is laminated on both sides of the UTG. One side is treated with a functional coating, and the other side is laminated with an OCA optical adhesive for easy screen lamination. The formed composite protection film has good bending resistance and a long service life; among them, the thermosetting resin has excellent dimensional stability, good corrosion resistance, high temperature resistance, wear resistance and excellent mechanical properties because it is insoluble and infusible, has high hardness, large specific rigidity, high temperature resistance and can form a stable and irreversible highly cross-linked network structure after curing, which can improve the scratch and wear resistance of the protection film; the functional base film has functions of anti-fingerprint, hardening, low reflection or anti-glare.

[0007] In particular, a large number of bubbles can be formed in the OCA adhesive layer of the present application by ultrasonic cavitation. The nano-silica particles wrapped by these bubbles and the molten hydroxy acrylic resin form a core-shell structure with nano-silica as the core and hydroxy acrylic resin as the shell. At the same time, the nano-silica with cations on the surface and the hydroxy acrylic resin promote the generation of this core-shell structure through electrostatic interaction, realizing uniform dispersion of nano-silica particles in the acrylic resin polymer, which can improve the elasticity of the acrylic OCA optical adhesive, avoid defects such as stress corrosion, delamination, cracking and fatigue of the protection film, and improve the bending resistance of the protection film.

[0008] Preferably, both the first thermosetting polymer film and the second thermosetting polymer film are epoxy resin films.

[0009] By adopting the above technical solutions, the epoxy resin film has excellent "wet state" adhesion to the substrate, low shrinkage rate (good dimensional stability), excellent chemical resistance and electrical insulation; the coating prepared from the epoxy resin has good leveling and wettability, can be constructed at normal temperature or lower temperature, and has excellent protection efficiency after crosslinking and curing into a coating film. The epoxy performance molecule contains ether aliphatic hydroxyl groups with strong polarity and not easy to hydrolyze. There are rigid phenyl groups and flexible hydrocarbon groups arranged alternately on the main chain. The ether bond structure endows the product with good flexibility and recovery. Its long-chain structure can also overcome the steric hindrance of the oligomer functional groups, better combine with the base film during curing, improve the bonding stability between layers, and prevent delamination or cracking of the protective sticker during use.

[0010] Preferably, the preparation method of the modified particles is as follows: adding nano-silica particles to an aqueous solution of a cationic surfactant and stirring, separating the solid and liquid, washing and drying the obtained solid phase to obtain the modified particles; The mass ratio of the nano-silica particles to the cationic surfactant is 1:1 - 3; The cationic surfactant is one or more of hydroxyethyl lauryl dimethyl ammonium chloride, dimethyldiallyl ammonium chloride, stearamide propyl dimethylamine, benzyl triethyl ammonium chloride, cetyl trimethyl ammonium bromide, and octadecyl dimethyl benzyl ammonium chloride.

[0011] By adopting the above technical solutions, the cationic surfactant combines with the negative charges on the surface of the nano-silica, and the surface of the modified nano-silica is positively charged, which can form a coating structure with the hydroxy acrylic resin through electrostatic interaction.

[0012] Preferably, the hydroxy acrylic resin is a linear hydroxy acrylic resin, and the synthesis method of the linear acrylic resin is as follows: Calculated by mass parts, the reaction monomers include 15 - 25 parts of methyl methacrylate, 15 - 25 parts of butyl acrylate, 20 - 35 parts of (meth)acrylic acid hydroxyethyl ester and / or (meth)acrylic acid hydroxypropyl ester, and 8 - 12 parts of isooctyl acrylate; mixing the reaction monomers with an initiator and stirring until completely dissolved to obtain a pre-mixed solution A, dropping the solution A into an organic solvent at 85 - 95 °C, carrying out a polymerization reaction at a temperature of 90 - 120 °C, and keeping warm for 2 - 4 h, and cooling to below 70 °C to obtain the linear hydroxy acrylic resin.

[0013] By adopting the above technical solutions, the prepared linear hydroxy acrylic resin has the characteristics of high viscoelasticity, and can further improve the elasticity of the acrylic resin.

[0014] Preferably, the hydroxy acrylic resin is a network hydroxy acrylic resin, and the synthesis method of the network hydroxy acrylic resin is as follows: adding the linear hydroxy acrylic resin into an organic solvent, adding an isocyanate crosslinking agent, and carrying out a crosslinking reaction at a temperature of 30-80°C to obtain the network hydroxy acrylic resin; The isocyanate crosslinking agent is one or more of toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, TDI trimer, and HDI trimer.

[0015] By adopting the above technical solution, multiple hydroxyl groups in the hydroxy acrylic resin react with the isocyanate groups in the isocyanate crosslinking agent to form a hydroxy acrylic resin with a spatial network structure. Due to the action of the spatial network structure system, the prepared acrylic resin has a large "viscoelastic effect", further improving the viscosity and elasticity of the acrylic OCA optical adhesive.

[0016] Preferably, the epoxy resin film is made of the following raw materials in parts by weight: 60-70 parts of epoxy resin, 15-35 parts of toughening agent, and 5-15 parts of curing agent, and the toughening agent is a core-shell particle with an organic montmorillonite as the core, rubber as the secondary outer layer, and polymer as the shell.

[0017] By adopting the above technical solution, the toughening agent in this application is a type of toughening agent with rubber-coated montmorillonite as the core and polymer as the shell. On the one hand, the rubber-coated inorganic nanoparticles effectively combine rubber and montmorillonite. When montmorillonite undergoes plastic deformation, it can effectively inhibit the propagation of cracks in the matrix resin and absorb part of the energy, thus playing a toughening role; at the same time, rubber particles, as stress concentration bodies, can not only induce crazes and shear bands to absorb energy, but also terminate crazes. The rubber elastic particles can also debond from the interface and release elastic strain energy, improving the toughening and bonding strength of the material; it can not only exert a toughening effect of 1+1>2 of the two, but also improve the flexibility of the nanoparticles; on the other hand, the polymer shell can be well compatible with the epoxy resin. When the core-shell ions are used, they only need to be blended with the epoxy resin. There is no process of phase dissolution and curing phase separation between the two. When the dispersion is good, the toughness of the system can be improved to a large extent. Since there is no rubber dissolved in the resin, the addition of the core-shell particles has little impact on the thermal properties of the epoxy resin.

[0018] Preferably, the preparation method of the toughening agent includes the following steps: (1) Stirring 1-3 parts by weight of organic montmorillonite in 100 parts by weight of deionized water at 40-50°C for 30-60 minutes to obtain a suspension; (2) Emulsify 20 parts by weight of silicone monomer, 1 - 5 parts by weight of emulsifier, 1 - 8 parts of silane coupling agent, 1 - 8 parts by weight of vinyl silane coupling agent, and 10 - 20 parts of deionized water for 5 - 10 min to obtain a silicone pre - emulsion; Mix 1 - 3 parts by weight of acid catalyst and 20 - 25 parts by weight of deionized water to obtain a silicone catalyst; Add 10 - 40% of the silicone pre - emulsion and 15 - 25% of the silicone catalyst to the suspension, stir and heat up for reaction, then add the remaining silicone emulsion and silicone catalyst to react to obtain a core - layer emulsion; (3) Emulsify 1 - 5 parts by weight of double - bond - containing monomer, 0.1 - 0.5 parts by weight of emulsifier, and 1 - 3 parts by weight of deionized water to obtain a double - bond - containing pre - emulsion; Mix 0.1 - 0.5 parts of initiator and 1 - 20 parts of deionized water to obtain an initiator solution; (4) Add the initiator solution to the core - layer emulsion, then add the double - bond - containing pre - emulsion to react to obtain a composite emulsion, and demulsify the composite emulsion to obtain the toughening agent.

[0019] By adopting the above - mentioned technical solution, this application uses in - situ emulsion reaction to introduce organic montmorillonite into the polymer to form a core - shell structure, which can not only toughen the epoxy resin, but also achieve good compatibility with the epoxy resin and be evenly dispersed in the epoxy resin, greatly improving the toughness of the system.

[0020] Preferably, in step (1), the organic montmorillonite is obtained by modifying montmorillonite with organic cations.

[0021] By adopting the above - mentioned technical solution, due to the strong hydrophilicity of the surface of montmorillonite, it is not conducive to its dispersion in the organic phase and wetting by the organic phase. By carrying out an organic modification treatment on montmorillonite, its surface becomes hydrophobic. Montmorillonite undergoes ion exchange with organic cations, so that the cations between its layers are replaced by organic cations. At the same time, since the surface of the lamellae is covered by organic groups, the surface properties of montmorillonite are changed, and its inner and outer surfaces change from hydrophilic to lipophilic, thus improving its compatibility with the polymer.

[0022] Preferably, in step (2), the silicone monomer is one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and low - molecular - weight hydroxy silicone oil; the silane coupling agent is one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltrimethoxysilane, and tetraethyl orthosilicate; the vinyl silane coupling agent is one or more of γ - methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; the acid catalyst is one or more of benzenesulfonic acid, p - toluenesulfonic acid, dodecylbenzenesulfonic acid, hydrochloric acid, and sulfuric acid; The emulsifier in steps (2) and (3) is one or more of sodium dodecylbenzenesulfonate, sodium dodecylsulfonate, dodecylbenzenesulfonic acid, didodecylphenyl ether disulfonate, isomeric tridecyl alcohol ether, and sorbitan monolaurate; In step (3), the double bond-containing monomer is one or more of styrene, methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, and lauryl methacrylate; the initiator is one of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0023] Preferably, the epoxy resin is one of bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, bisphenol F epoxy resin, cycloaliphatic epoxy resin, polyfunctional glycidyl ester, linear phenolic epoxy resin, and brominated epoxy resin.

[0024] Preferably, the method for preparing the epoxy resin film is as follows: adding the epoxy resin and the curing agent into an acetone solution according to the ratio and mixing to obtain a blend solution, adding the toughening agent into the blend solution and mixing to obtain a dispersion; coating the dispersion on a release film to obtain the epoxy resin film.

[0025] Preferably, the thickness of the epoxy resin film is 10 - 100 μm; The thickness of the functional base film is 25 - 75 μm; The thickness of the UTG ultra-thin glass layer is 30 - 150 μm; The thickness of the OCA adhesive layer is 10 - 100 μm.

[0026] In the second aspect, the present application provides a method for preparing a composite glass protective film for a flexible folding screen, adopting the following technical solution, A method for preparing a composite glass protective film for a flexible folding screen, comprising the following steps: Stacking a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass, and a second thermosetting polymer film from top to bottom in sequence, and using hot pressing to press the film layers together to form a composite layer; Bonding the OCA adhesive layer to the second thermosetting polymer film in the composite layer to form a composite glass protective film.

[0027] In summary, the present application has the following beneficial effects: 1. In the OCA adhesive layer of this application, a large number of bubbles can be formed by the ultrasonic cavitation effect. The nano-silica particles wrapped by these bubbles and the molten hydroxyacrylic resin form a core-shell structure with nano-silica as the core and hydroxyacrylic resin as the shell. At the same time, the nano-silica with cations on the surface and the hydroxyacrylic resin promote the generation of this core-shell structure through electrostatic interaction, realizing the uniform dispersion of nano-silica particles in the acrylic resin polymer. It can improve the elasticity of acrylic OCA optical adhesive, avoid the defects of stress corrosion, delamination, cracking and fatigue of the protective film, and improve the bending resistance of the protective film.

[0028] 2. The linear hydroxyacrylic resin prepared in this application has the characteristic of high viscoelasticity, which can further improve the elasticity of the acrylic resin.

[0029] 3. The network hydroxyacrylic resin prepared in this application has a large "viscoelastic effect" due to the action of the space network structure system, further improving the viscosity and elasticity of the acrylic OCA optical adhesive.

[0030] 4. The toughening agent in this application is a core-shell particle with organic montmorillonite as the core, rubber as the secondary outer layer, and polymer as the shell. Using organic montmorillonite and rubber as the core layer can not only play a toughening effect of 1 + 1 > 2, but also improve the flexibility of nano-particles. On the other hand, the polymer shell can achieve good compatibility with epoxy resin. Description of the Drawings

[0031] Figure 1 It is the infrared spectrogram of the hydroxyacrylic resin prepared in Preparation Example 1. Detailed Description of the Embodiments

[0032] The following further describes this application in detail with reference to the embodiments.

[0033] The raw materials of the examples and comparative examples of this application are all commercially available, unless otherwise specified.

[0034] Preparation of Hydroxyacrylic Resin in Preparation Examples 1 - 7 Preparation Example 1 25 g of methyl methacrylate, 25 g of butyl acrylate, 15 g of hydroxyethyl acrylate, 15 g of hydroxypropyl acrylate, 10 g of isooctyl acrylate and 1 g of azobisisobutyronitrile were stirred and mixed until completely dissolved to obtain a pre-mixed solution A. The mixed solution A was dropped into 30 g of tetrahydrofuran at 90 °C, and a polymerization reaction was carried out at 105 °C and kept warm for 3 h, and then cooled to below 70 °C to obtain a linear hydroxyacrylic resin.

[0035] Preparation Example 2 25 g of methyl methacrylate, 25 g of butyl acrylate, 15 g of 2-hydroxyethyl acrylate, 15 g of 2-hydroxypropyl acrylate, 10 g of isooctyl acrylate and 1 g of azobisisobutyronitrile were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 90 °C, and a polymerization reaction was carried out at 105 °C and kept warm for 3 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin. 0.1 mol of the linear hydroxy acrylic resin was added to 300 ml of propylene glycol monomethyl ether acetate, and 0.04 mol of isophorone diisocyanate crosslinking agent was added for crosslinking at a temperature of 50 °C to obtain a network hydroxy acrylic resin.

[0036] Preparation Example 3 15 g of methyl methacrylate, 15 g of butyl acrylate, 35 g of 2-hydroxyethyl acrylate, 8 g of isooctyl acrylate and 1 g of azobisisobutyronitrile were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 90 °C, and a polymerization reaction was carried out at 105 °C and kept warm for 3 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin.

[0037] Preparation Example 4 15 g of methyl methacrylate, 15 g of butyl acrylate, 35 g of 2-hydroxypropyl acrylate, 8 g of isooctyl acrylate and 1 g of azobisisobutyronitrile were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 90 °C, and a polymerization reaction was carried out at 105 °C and kept warm for 3 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin.

[0038] Preparation Example 5 35 g of methyl methacrylate, 35 g of butyl acrylate, 10 g of 2-hydroxyethyl acrylate, 10 g of 2-hydroxypropyl acrylate, 10 g of isooctyl acrylate and 1 g of azobisisobutyronitrile were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 90 °C, and a polymerization reaction was carried out at 105 °C and kept warm for 3 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin.

[0039] Preparation Example 6 25 g of methyl methacrylate, 25 g of butyl acrylate, 15 g of 2-hydroxyethyl acrylate, 15 g of 2-hydroxypropyl acrylate, 10 g of isooctyl acrylate and 1 g of azobisisobutyronitrile were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 85 °C, and a polymerization reaction was carried out at 90 °C and kept warm for 4 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin.

[0040] Preparation Example 7 25 g of methyl methacrylate, 25 g of butyl acrylate, 15 g of 2-hydroxyethyl acrylate, 15 g of 2-hydroxypropyl acrylate, 10 g of isooctyl acrylate and 1 g of 2,2'-azobis(isobutyronitrile) were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 95 °C, and a polymerization reaction was carried out at 120 °C and kept warm for 2 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin.

[0041] The elastic properties of the hydroxy acrylic resins prepared in Preparation Examples 1-7 were tested with reference to GB / T 1040, and the specific data are recorded in Table 1.

[0042] Table 1 Performance test data of the hydroxy acrylic resins prepared in Preparation Examples 1-7

[0043] Referring to Table 1, it can be seen that the hydroxy content of the hydroxy acrylates in Preparation Examples 3 and 4 is relatively higher than that in Preparation Example 1, while the hydroxy content in Preparation Example 5 is relatively lower than that in Preparation Example 1. An appropriate amount of hydroxy groups (provided by 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate) as crosslinking reaction active sites can form a three-dimensional network with medium density (crosslinking degree 75%-80%) with the crosslinking agent, which can not only avoid the sudden increase in resin viscosity and brittleness defects caused by high hydroxy content, but also prevent insufficient crosslinking and decrease in adhesion caused by low hydroxy content. At the same time, the hydroxy groups form chemical anchoring with the surface silanol groups of nano-silica through hydrogen bonding or covalent bonding, and synergistically promote the uniform dispersion of the "hard core-soft shell" core-shell structure through the ultrasonic cavitation effect. By adjusting the content of acrylic monomers and reaction parameters, acrylic resins with different elastic properties can be obtained. By comparison, it is found that 25 g of methyl methacrylate, 25 g of butyl acrylate, 15 g of 2-hydroxyethyl acrylate, 15 g of 2-hydroxypropyl acrylate, 10 g of isooctyl acrylate and 1 g of 2,2'-azobis(isobutyronitrile) were stirred and mixed until completely dissolved to obtain a premixed solution A. The mixed solution A was added dropwise to 30 g of tetrahydrofuran at 90 °C, and a polymerization reaction was carried out at 105 °C and kept warm for 3 h, and then cooled to below 70 °C to obtain a linear hydroxy acrylic resin with the highest elastic modulus and the highest elasticity. At the same time, the infrared spectrum of the hydroxy acrylic resin in Preparation Example 1 is as Figure 1 shown.

[0044] Preparation Examples 8-12 OCA adhesive layer Preparation Example 8 S1: Add 5 g of nano-silica particles into 24 L of deionized water, and use a magnetic stirrer to stir and disperse at a speed of 600 rpm to obtain a dispersion; add 5 g of octadecyl dimethyl benzyl ammonium chloride, stir and react for 2 h, perform solid-liquid separation, repeatedly wash the obtained solid phase with deionized water and ethanol, and dry to obtain modified particles; use a Zeta potential analyzer to measure the potential of the modified particles, and it is measured that the surface of the modified nano-silica is positively charged; S2: Add 5 g of hydroxy acrylic resin from the main feeding port of the twin-screw extruder, add 5 g of modified particles from the side feeding port, introduce an ultrasonic generating device at a position close to the side feeding port, and under the condition of an ultrasonic power of 600 W, obtain an elastic acrylic masterbatch through extrusion granulation; S3: Mix 9.5 g of elastic acrylic masterbatch, 0.15 g of ethylene glycol diacrylate and 0.35 g of photoinitiator 1173 evenly to obtain an acrylic OCA optical adhesive for standby; S4: Use an automatic coating device to coat the acrylic OCA optical adhesive on one side of the release film, and obtain an OCA adhesive layer with a thickness of 50 μm after ultraviolet curing.

[0045] Preparation Example 9 S1: Add 0.5 g of nano-silica particles into 2.4 L of deionized water, and use a magnetic stirrer to stir and disperse at a speed of 600 rpm to obtain a dispersion; add 1 g of cetyl trimethyl ammonium bromide, stir and react for 2 h, perform solid-liquid separation, repeatedly wash the obtained solid phase with deionized water and ethanol, and dry to obtain modified particles; use a Zeta potential analyzer to measure the potential of the modified particles, and it is measured that the surface of the modified nano-silica is positively charged; S2: Add 10 g of hydroxy acrylic resin from the main feeding port of the twin-screw extruder, add 5 g of modified particles from the side feeding port, introduce an ultrasonic generating device at a position close to the side feeding port, and under the condition of an ultrasonic power of 800 W, obtain an elastic acrylic masterbatch through extrusion granulation; S3: Mix 9.5 g of elastic acrylic masterbatch, 0.15 g of ethylene glycol diacrylate and 0.35 g of photoinitiator 1173 evenly to obtain an acrylic OCA optical adhesive for standby; S4: Use an automatic coating device to coat the acrylic OCA optical adhesive on one side of the release film, and obtain an OCA adhesive layer with a thickness of 50 μm after ultraviolet curing.

[0046] Preparation Example 10 S1: Add 0.5 g of nano-silica particles into 2.4 L of deionized water, and use a magnetic stirrer to stir and disperse at a speed of 600 rpm to obtain a dispersion; add 1.5 g of dimethyldiallylammonium chloride, stir and react for 2 h, perform solid-liquid separation, repeatedly wash the obtained solid phase with deionized water and ethanol, and dry to obtain modified particles; use a Zeta potential analyzer to measure the potential of the modified particles, and it is measured that the surface of the modified nano-silica is positively charged; S2: Add 15 g of hydroxy acrylic resin from the main feeding port of the twin-screw extruder, add 5 g of modified particles from the side feeding port, introduce an ultrasonic generating device at a position close to the side feeding port, and under the condition of an ultrasonic power of 1000 W, obtain an elastic acrylic masterbatch through extrusion granulation; S3: Mix 9.5 g of elastic acrylic masterbatch, 0.15 g of ethylene glycol diacrylate and 0.35 g of photoinitiator 1173 evenly to obtain an acrylic OCA optical adhesive for standby; S4: Use an automatic coating device to coat the acrylic OCA optical adhesive on one side of the release film, and obtain an OCA adhesive layer with a thickness of 50 μm after ultraviolet curing.

[0047] Preparation Example 11 S1: Add 0.5 g of nano-silica particles into 2.4 L of deionized water, and use a magnetic stirrer to stir and disperse at a speed of 600 rpm to obtain a dispersion; add 1 g of cetyltrimethylammonium bromide, stir and react for 2 h, perform solid-liquid separation, repeatedly wash the obtained solid phase with deionized water and ethanol, and dry to obtain modified particles; use a Zeta potential analyzer to measure the potential of the modified particles, and it is measured that the surface of the modified nano-silica is positively charged; S2: Add 10 g of linear hydroxy acrylic resin from the main feeding port of the twin-screw extruder, add 5 g of modified particles from the side feeding port, introduce an ultrasonic generating device at a position close to the side feeding port, and under the condition of an ultrasonic power of 600 W, obtain an elastic acrylic masterbatch through extrusion granulation; where the linear hydroxy acrylic resin is from Preparation Example 1; S3: Mix 9.5 g of elastic acrylic masterbatch, 0.15 g of ethylene glycol diacrylate and 0.35 g of photoinitiator 1173 evenly to obtain an acrylic OCA optical adhesive for standby; S4: Use an automatic coating device to coat the acrylic OCA optical adhesive on one side of the release film, and obtain an OCA adhesive layer with a thickness of 50 μm after ultraviolet curing.

[0048] Preparation Example 12 S1: Add 0.5 g of nano-silica particles into 2.4 L of deionized water, and use a magnetic stirrer to stir and disperse at a speed of 600 rpm to obtain a dispersion; add 1 g of cetyltrimethylammonium bromide, stir and react for 2 h, perform solid-liquid separation, and repeatedly wash the obtained solid phase with deionized water and ethanol, and dry to obtain modified particles; use a Zeta potential meter to measure the potential of the modified particles, and it is measured that the surface of the modified nano-silica is positively charged; S2: Add 10 g of reticulated hydroxyacrylic resin from the main feeding port of a twin-screw extruder, add 5 g of modified particles from the side feeding port, introduce an ultrasonic generating device at a position close to the side feeding port, and under the condition of an ultrasonic power of 600 W, obtain an elastic acrylic masterbatch through extrusion granulation; wherein the reticulated hydroxyacrylic resin comes from Preparation Example 2; S3: Mix 9.5 g of elastic acrylic masterbatch, 0.15 g of ethylene glycol diacrylate and 0.35 g of photoinitiator 1173 evenly to obtain an acrylic OCA optical adhesive for standby; S4: Use an automatic coating device to coat the acrylic OCA optical adhesive on one side of a release film, and obtain an OCA adhesive layer with a thickness of 50 μm after ultraviolet curing.

[0049] Preparation Examples 13-18 Epoxy Resin Films Preparation Example 13 (1) Add 5 g of montmorillonite into 20 L of deionized water, use a magnetic stirrer to stir and disperse at a speed of 500 rpm to obtain a suspension, let it stand for 24 h, take the upper-layer suspension for centrifugal filtration, and dry to obtain purified montmorillonite; weigh 3 g of purified montmorillonite and add it to 100 ml of deionized water to prepare a dispersion, stir evenly and then dropwise add a 2 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 5. Dissolve 0.6 g of cetyltrimethylammonium bromide in 50 ml of water, slightly heat it to completely dissolve, then dropwise add it to the dispersion, heat to 80 °C, keep it at a constant temperature of 800 rpm for 3 h, cool, filter, wash, dry, grind, and pass through a 200-mesh sieve to obtain organic montmorillonite; stir 1 g of organic montmorillonite in 100 g of deionized water at 40 °C for 30 min to obtain a suspension; 20 g of hexamethylcyclotrisiloxane, 1 g of sodium dodecylbenzenesulfonate, 1 g of methyltrimethoxysilane, 1 g of γ-methacryloyloxypropyltrimethoxysilane and 10 g of deionized water were emulsified for 5 min to obtain a silicone pre-emulsion; 1 g of benzenesulfonic acid and 20 g of deionized water were mixed to obtain a silicone catalyst; the above 10% silicone pre-emulsion and 15% silicone catalyst were added to the above suspension, stirred and heated to 75 °C, reacted for 1 h, then the remaining silicone pre-emulsion and silicone catalyst were added and heated to 80 °C for constant temperature reaction for 3 h, and the pH was adjusted to 9 to obtain a core layer emulsion; 1 g of styrene, 0.1 g of sodium dodecylbenzenesulfonate and 1 g of deionized water were emulsified to obtain a double bond-containing pre-emulsion; 0.1 g of potassium persulfate and 1 g of deionized water were mixed to obtain an initiator; the above initiator was added to the core layer emulsion, and then the above double bond-containing emulsion was added and reacted at 80 °C for 1.5 h, and then cooled to 25 °C to obtain a composite emulsion; 35 g of 5 wt% potassium chloride aqueous solution was added to the composite emulsion for demulsification, and the precipitate was washed with water to remove residual monomers and emulsifiers, and dried to obtain a toughening agent; (2) 60 g of bisphenol A epoxy resin and 5 g of 4,4 ， -diaminodiphenylmethane were mixed and added to an acetone solvent. After complete dissolution, a blend solution was obtained. 35 g of the toughening agent was added to the blend solution and dispersed for 15 min to obtain a dispersion solution. The dispersion solution was coated on a release film, and the thickness of the epoxy resin film was controlled to be 30 μm.

[0050] Preparation Example 14 (1) 5 g of montmorillonite was added to 20 L of deionized water, and stirred and dispersed at a speed of 500 rpm using a magnetic stirrer to obtain a suspension. It was left standing for 24 h, and the upper layer suspension was taken for centrifugal filtration and dried to obtain purified montmorillonite; 3 g of the purified montmorillonite was weighed and added to 100 ml of deionized water to prepare a dispersion. After stirring evenly, 2 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 5. 0.6 g of cetyltrimethylammonium bromide was dissolved in 50 ml of water, slightly heated to completely dissolve it, and then added dropwise to the dispersion. It was heated to 80 °C and reacted at a constant temperature of 800 rpm for 3 h, cooled, filtered by suction, washed, dried, ground, and passed through a 200-mesh sieve to obtain organophilic montmorillonite; 2 g of the organophilic montmorillonite was stirred in 100 g of deionized water at 45 °C for 45 min to obtain a suspension; 20 g of octamethylcyclotetrasiloxane, 3 g of sodium dodecyl sulfonate, 5 g of methyltriethoxysilane, 5 g of vinyltrimethoxysilane and 15 g of deionized water were emulsified for 8 min to obtain a silicone pre-emulsion; 2 g of p-toluenesulfonic acid and 22 g of deionized water were mixed to obtain a silicone catalyst; the above 25% silicone pre-emulsion and 20% silicone catalyst were added to the above suspension, stirred and heated to 75 °C, reacted for 1 h, then the remaining silicone pre-emulsion and silicone catalyst were added, heated to 80 °C and reacted at a constant temperature for 3 h, and the pH was adjusted to 9 to obtain a core layer emulsion; 3 g of methyl methacrylate, 0.3 g of sodium dodecyl sulfonate and 2 g of deionized water were emulsified to obtain a double bond-containing pre-emulsion; 0.3 g of sodium persulfate and 10 g of deionized water were mixed to obtain an initiator; the above initiator was added to the core layer emulsion, and then the above double bond-containing emulsion was added and reacted at 80 °C for 1.5 h, and the temperature was lowered to 25 °C to obtain a composite emulsion; 35 g of 5 wt% potassium chloride aqueous solution was added to the composite emulsion for demulsification, and the precipitate was washed with water to remove residual monomers and emulsifiers, and dried to obtain a toughening agent; (2) 65 g of hydrogenated bisphenol A epoxy resin and 10 g of 4,4 ， -diaminodiphenylmethane were mixed and added to an acetone solvent. After complete dissolution, a blend solution was obtained. 25 g of the toughening agent was added to the blend solution and dispersed for 15 min to obtain a dispersed solution. The dispersed solution was coated on a release film, and the thickness of the epoxy resin film was controlled to be 30 μm.

[0051] Preparation Example 15 (1) 5 g of montmorillonite was added to 20 L of deionized water, and stirred and dispersed at a speed of 500 rpm using a magnetic stirrer to obtain a suspension. After standing for 24 h, the upper layer suspension was taken for centrifugal filtration, dried to obtain purified montmorillonite; 3 g of the purified montmorillonite was weighed and added to 100 ml of deionized water to prepare a dispersion. After stirring evenly, 2 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 5. 0.6 g of cetyltrimethylammonium bromide was dissolved in 50 ml of water, slightly heated to completely dissolve it, and then added dropwise to the dispersion. It was heated to 80 °C and reacted at a constant temperature at 800 rpm for 3 h, cooled, filtered by suction, washed, dried, ground, and passed through a 200-mesh sieve to obtain organophilic montmorillonite; 3 g of the organophilic montmorillonite was stirred in 100 g of deionized water at 50 °C for 60 min to obtain a suspension; 20 g of low molecular weight hydroxy silicone oil (CAS: 70131-67-8), 5 g of dodecylbenzenesulfonic acid, 8 g of phenyltrimethoxysilane, 8 g of vinyltriethoxysilane and 20 g of deionized water were emulsified for 8 min to obtain an organosilicon pre-emulsion; 3 g of dodecylbenzenesulfonic acid and 25 g of deionized water were mixed to obtain an organosilicon catalyst; the above 25% organosilicon pre-emulsion and 20% organosilicon catalyst were added to the above suspension, stirred and heated to 75 °C, reacted for 1 h, then the remaining organosilicon pre-emulsion and organosilicon catalyst were added, heated to 80 °C and kept at a constant temperature for 3 h, and the pH was adjusted to 9 to obtain a core layer emulsion; 5 g of butyl acrylate, 0.5 g of dodecylbenzenesulfonic acid and 3 g of deionized water were emulsified to obtain a double bond-containing pre-emulsion; 0.5 g of ammonium persulfate and 20 g of deionized water were mixed to obtain an initiator; the above initiator was added to the core layer emulsion, and then the above double bond-containing emulsion was added, and the reaction was carried out at 80 °C for 1.5 h, and then cooled to 25 °C to obtain a composite emulsion; 35 g of 5 wt% potassium chloride aqueous solution was added to the composite emulsion for demulsification, and the precipitate was washed with water to remove residual monomers and emulsifiers, and dried to obtain a toughening agent; (2) 70 g of bisphenol F type epoxy resin and 15 g of 4,4 ， -diaminodiphenylmethane were mixed and added to an acetone solvent, and after complete dissolution, a blend solution was obtained. 15 g of the toughening agent was added to the blend solution and dispersed for 15 min to obtain a dispersed solution. The dispersed solution was coated on a release film, and the thickness of the epoxy resin film was controlled to be 30 μm.

[0052] Preparation Example 16 (1) 5 g of montmorillonite was added to 20 L of deionized water, and stirred and dispersed at a speed of 500 rpm using a magnetic stirrer to obtain a suspension. After standing for 24 h, the upper layer suspension was taken for centrifugal filtration, dried to obtain purified montmorillonite; 3 g of the purified montmorillonite was weighed and added to 100 ml of deionized water to prepare a dispersion. After stirring evenly, 2 mol / L hydrochloric acid solution was added dropwise to adjust the pH of the dispersion to 5. 0.6 g of cetyltrimethylammonium bromide was dissolved in 50 ml of water, slightly heated to completely dissolve it, and then added dropwise to the dispersion, heated to 80 °C, kept at a constant temperature and reacted at 800 rpm for 3 h, cooled, filtered by suction, washed, dried, ground, and passed through a 200-mesh sieve to obtain organophilic montmorillonite; (2) 65 g of hydrogenated bisphenol A type epoxy resin and 10 g of 4,4, -diaminodiphenylmethane were mixed and added to an acetone solvent, and after complete dissolution, a blend solution was obtained. 25 g of organophilic montmorillonite (toughening agent) was added to the blend solution and dispersed for 15 min to obtain a dispersed solution. The dispersed solution was coated on a release film, and the thickness of the epoxy resin film was controlled to be 30 μm.

[0053] Preparation Example 17 (1) Emulsify 20 g of octamethylcyclotetrasiloxane, 3 g of sodium dodecyl sulfonate, 5 g of methyltriethoxysilane, 5 g of vinyltrimethoxysilane, and 15 g of deionized water for 8 min to obtain a silicone pre-emulsion; mix 2 g of p-toluenesulfonic acid and 22 g of deionized water to obtain a silicone catalyst; stir 1 g of sodium dodecylbenzenesulfonate and 10 g of deionized water, heat up to 55 °C, then add the above 25% silicone pre-emulsion and 20% silicone catalyst to the above suspension, stir and heat up to 80 °C, react for 1 h, then add the remaining silicone pre-emulsion and silicone catalyst, react at a constant temperature for 3 h, and adjust the pH to 9 to obtain a core layer emulsion; emulsify 3 g of methyl methacrylate, 0.3 g of sodium dodecyl sulfonate, and 2 g of deionized water to obtain a double bond-containing pre-emulsion; mix 0.3 g of sodium persulfate and 10 g of deionized water to obtain an initiator; stir 10 g of the above core layer emulsion and 1 g of sodium dodecylbenzenesulfonate, heat up to 80 °C, and add the above initiator and double bond-containing emulsion, react at a constant temperature for 1.5 h, cool down to 25 °C to obtain a composite emulsion; add 35 g of 5 wt% potassium chloride aqueous solution to the composite emulsion for demulsification, wash the precipitate with water to remove residual monomers and emulsifiers, and dry to obtain a nano-silicone rubber core-shell polymer; (2) Mix 65 g of hydrogenated bisphenol A epoxy resin and 10 g of 4,4 ， -diaminodiphenylmethane and add them to an acetone solvent. After complete dissolution, a blend solution is obtained. Add 25 g of nano-silicone rubber core-shell polymer (toughening agent) to the blend solution, disperse for 15 min to obtain a dispersed solution, coat the dispersed solution on a release film, and control the thickness of the epoxy resin film to be 30 μm.

[0054] Preparation Example 18 (1) Add 5 g of montmorillonite to 20 L of deionized water, stir and disperse it at a speed of 500 rpm using a magnetic stirrer to obtain a suspension. Let it stand for 24 h, take the upper layer suspension, centrifuge and filter it, and dry it to obtain purified montmorillonite; weigh 3 g of purified montmorillonite, add it to 100 ml of deionized water to prepare a dispersion, stir evenly, and then gradually add 2 mol / L hydrochloric acid solution to adjust the pH of the dispersion to 5. Dissolve 0.6 g of cetyltrimethylammonium bromide in 50 ml of water, slightly heat it to completely dissolve it, then gradually add it to the dispersion, heat to 80 °C, react at a constant temperature at 800 rpm for 3 h, cool, filter, wash, dry, grind, and pass through a 200-mesh sieve to obtain organophilic montmorillonite; (2) 20 g of octamethylcyclotetrasiloxane, 3 g of sodium dodecylsulfonate, 5 g of methyltriethoxysilane, 5 g of vinyltrimethoxysilane and 15 g of deionized water were emulsified for 8 min to obtain a silicone pre-emulsion; 2 g of p-toluenesulfonic acid and 22 g of deionized water were mixed to obtain a silicone catalyst; 1 g of sodium dodecylbenzenesulfonate and 10 g of deionized water were stirred and heated to 55 °C, then the above 25% silicone pre-emulsion and 20% silicone catalyst were added to the above suspension, stirred and heated to 80 °C, reacted for 1 h, then the remaining silicone pre-emulsion and silicone catalyst were added and reacted at a constant temperature for 3 h, and the pH was adjusted to 9 to obtain a core layer emulsion; 3 g of methyl methacrylate, 0.3 g of sodium dodecylsulfonate and 2 g of deionized water were emulsified to obtain a double bond-containing pre-emulsion; 0.3 g of sodium persulfate and 10 g of deionized water were mixed to obtain an initiator; the above 10 g of core layer emulsion and 1 g of sodium dodecylbenzenesulfonate were stirred and heated to 80 °C, and the above initiator and double bond-containing emulsion were added and reacted at a constant temperature for 1.5 h, then cooled to 25 °C to obtain a composite emulsion; 35 g of 5 wt% potassium chloride aqueous solution was added to the composite emulsion for demulsification, and the precipitate was washed with water to remove residual monomers and emulsifiers, and after drying, a nano-silicone rubber core-shell polymer was obtained; (3) 65 g of hydrogenated bisphenol A epoxy resin and 10 g of 4,4 ， -diaminodiphenylmethane were mixed and added to an acetone solvent, and after complete dissolution, a blend solution was obtained. 5 g of organic montmorillonite and 25 g of nano-silicone rubber core-shell polymer (toughening agent) were added to the blend solution and dispersed for 15 min to obtain a dispersed solution. The dispersed solution was coated on a release film, and the thickness of the epoxy resin film was controlled to be 30 μm.

[0055] Example 1 This example provides a composite glass protection film for a flexible folding screen, which sequentially includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film and an OCA adhesive layer from top to bottom.

[0056] This example also provides a preparation method of the above composite glass protection film for a flexible folding screen, including the following steps: Sequentially from top to bottom, the functional base film, the first thermosetting polymer film, the UTG ultra-thin glass layer, and the second thermosetting polymer film were mutually pressed by vacuum hot pressing to form a composite layer. Among them, the temperature during vacuum hot pressing was 150 °C. The size of the thermosetting polymer film was 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film was obtained by etching a polydimethylsiloxane film with femtosecond laser irradiation to make the film have an anti-fingerprint effect. Its size was 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness was 25 μm; the first thermosetting polymer film and the second thermosetting polymer film both came from Preparation Example 16; the UTG ultra-thin glass layer was a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated to the second thermosetting polymer layer in the composite layer using a laminating device, and then a protective film is formed by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 8, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0057] Example 2 This example provides a composite glass protective film for a flexible folding screen, which sequentially includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0058] This example also provides a preparation method for the above-mentioned composite glass protective film for a flexible folding screen, including the following steps: The functional base film, the first thermosetting polymer film, the UTG ultra-thin glass layer, and the second thermosetting polymer film are sequentially laminated to each other by vacuum hot pressing from top to bottom to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is a polydimethylsiloxane film etched by femtosecond laser to make the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and its thickness is 25 μm. The first thermosetting polymer film and the second thermosetting polymer film are both from Preparation Example 16. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated to the second thermosetting polymer layer in the composite layer using a laminating device, and then a protective film is formed by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 9, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0059] Example 3 This example provides a composite glass protective film for a flexible folding screen, which sequentially includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0060] This example also provides a preparation method for the above-mentioned composite glass protective film for a flexible folding screen, including the following steps: From top to bottom, a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, and a second thermosetting polymer film are mutually laminated by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is obtained by femtosecond laser-induced etching of a polydimethylsiloxane film, making the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm. Both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 16. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG through a strengthening process. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then a protective sticker is made by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 10, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0061] Example 4 This example provides a composite glass protective sticker for a flexible folding screen, which from top to bottom is a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer.

[0062] This example also provides a preparation method for the above-mentioned composite glass protective sticker for a flexible folding screen, including the following steps: From top to bottom, a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, and a second thermosetting polymer film are mutually laminated by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is obtained by femtosecond laser-induced etching of a polydimethylsiloxane film, making the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm. Both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 16. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG through a strengthening process. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then a protective sticker is made by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 11, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0063] Example 5 This example provides a composite glass protective sticker for a flexible folding screen, which from top to bottom is a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer.

[0064] This embodiment also provides a preparation method of the above-mentioned composite glass protective film for flexible folding screens, including the following steps: From top to bottom, a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, and a second thermosetting polymer film are sequentially laminated with each other by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is a polydimethylsiloxane film etched by femtosecond laser to make the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm. Both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 16. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG by a strengthening process; The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the protective film is formed by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 12, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0065] Example 6 This embodiment provides a composite glass protective film for flexible folding screens, which includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0066] This embodiment also provides a preparation method of the above-mentioned composite glass protective film for flexible folding screens, including the following steps: From top to bottom, a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, and a second thermosetting polymer film are sequentially laminated with each other by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is a polydimethylsiloxane film etched by femtosecond laser to make the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm. Both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 17. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG by a strengthening process; The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the protective film is formed by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 12, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0067] Example 7 This embodiment provides a composite glass protective film for flexible folding screens, which includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0068] This embodiment also provides a method for preparing the above-mentioned composite glass protective film for flexible folding screens, which includes the following steps: From top to bottom, a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, and a second thermosetting polymer film are sequentially laminated with each other by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is obtained by etching a polydimethylsiloxane film with femtosecond laser, making the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm. Both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 18. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the protective film is formed by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 12, and its outer shape size is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0069] Example 8 This embodiment provides a composite glass protective film for flexible folding screens, which from top to bottom is sequentially a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer.

[0070] This embodiment also provides a method for preparing the above-mentioned composite glass protective film for flexible folding screens, which includes the following steps: From top to bottom, a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, and a second thermosetting polymer film are sequentially laminated with each other by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150 °C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is obtained by etching a polydimethylsiloxane film with femtosecond laser, making the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm. Both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 15. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the protective film is formed by laser cutting the outer shape. The OCA adhesive layer is from Preparation Example 12, and its outer shape size is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0071] Example 9 This embodiment provides a composite glass protective film for a flexible folding screen, which includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0072] This embodiment also provides a preparation method for the above-mentioned composite glass protective film for a flexible folding screen, including the following steps: From top to bottom, the functional base film, the first thermosetting polymer film, the UTG ultra-thin glass layer, and the second thermosetting polymer film are sequentially laminated with each other by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150°C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is obtained by etching a polydimethylsiloxane film with femtosecond laser irradiation, making the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and its thickness is 25 μm. The first thermosetting polymer film and the second thermosetting polymer film both come from Preparation Example 14. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the protective film is formed by laser cutting the outer shape. The OCA adhesive layer comes from Preparation Example 12, and its outer shape size is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0073] Example 10 This embodiment provides a composite glass protective film for a flexible folding screen, which includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0074] This embodiment also provides a preparation method for the above-mentioned composite glass protective film for a flexible folding screen, including the following steps: From top to bottom, the functional base film, the first thermosetting polymer film, the UTG ultra-thin glass layer, and the second thermosetting polymer film are sequentially laminated with each other by vacuum hot pressing to form a composite layer. The temperature during vacuum hot pressing is 150°C. The size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass. The functional base film is obtained by etching a polydimethylsiloxane film with femtosecond laser irradiation, making the film have an anti-fingerprint effect. Its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and its thickness is 25 μm. The first thermosetting polymer film and the second thermosetting polymer film both come from Preparation Example 13. The UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the protective film is formed by laser cutting the outer shape. The OCA adhesive layer comes from Preparation Example 12, and its outer shape size is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0075] Comparative Example 1 This comparative example provides a composite glass protective film for a flexible folding screen, which successively includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film, and an OCA adhesive layer from top to bottom.

[0076] This comparative example also provides a preparation method of the above-mentioned composite glass protective film for a flexible folding screen, including the following steps: From top to bottom, the functional base film, the first thermosetting polymer film, the UTG ultra-thin glass layer, and the second thermosetting polymer film are mutually laminated by vacuum hot pressing to form a composite layer. Among them, the temperature during vacuum hot pressing is 150 °C, the size of the thermosetting polymer film is 5 mm larger than the outer shape of the UTG ultra-thin glass, the functional base film is a polydimethylsiloxane film etched by femtosecond laser to make the film have an anti-fingerprint effect, its size is 5 mm larger than the outer shape of the UTG ultra-thin glass, and the thickness is 25 μm; both the first thermosetting polymer film and the second thermosetting polymer film are from Preparation Example 16; the UTG ultra-thin glass layer is a 30-μm glass obtained by strengthening the UTG. The OCA adhesive layer is laminated with the second thermosetting polymer layer in the composite layer using a laminating device, and then the outer shape is cut by laser to make a protective film. The preparation method of the OCA adhesive layer is as follows: 9.5 g of elastic acrylic masterbatch, 0.15 g of ethylene glycol diacrylate, and 0.35 g of photoinitiator 1173 are mixed evenly to obtain an acrylic OCA optical adhesive for standby; an automatic coating device is used to coat the acrylic OCA optical adhesive on one side of the release film, and after ultraviolet curing, an OCA adhesive layer with a thickness of 50 μm is obtained, and its outer dimension is 2 mm larger than the outer shape of the UTG ultra-thin glass.

[0077] Performance Testing Testing Standards: Flexural Resistance Test: The OCA adhesive layer in the composite glass protective films prepared in Examples 1-10 and Comparative Example 1 is attached to a 0.1-mm flexible tempered film, and then fixed on a folding screen test fixture. A LW-102W folding screen flexural life testing machine is used for the flexural property test. The test temperature is 25 °C, the bending radius R = 2.0 mm, and the bending angle is 180°. The test is applied to the unfolded and folded states of the folding screen flexural resistance protective film, and 200,000 times and 250,000 times of bending tests are carried out respectively. When the test reaches 200,000 times, the experiment is stopped, and it is observed whether the protective film shows phenomena such as bubbles, cracks, peeling, and folding. If so, the number of times is recorded as 200,000 times. If there are no such phenomena, the test continues. When folding reaches 250,000 times, the experiment is stopped, and it is observed whether the protective film shows phenomena such as bubbles, cracks, peeling, and folding. If so, the number of times is recorded as 250,000 times. If there are no such phenomena, the folding times are recorded as > 250,000 times.

[0078] Impact resistance test: Referring to the standard of GB / T2423.8-1995, the composite glass protection films prepared in Examples 1-10 and Comparative Example 1 were tested using an MK-2M-DX directional drop tester. It is required that the protection film adhered to the 3D mobile phone is flat, tight, bubble-free and wrinkle-free. Place the display screen of the 3D mobile phone facing down and drop it freely on a plane with a height of 1.0 m onto the concrete surface. After a total of 50 drops, observe the proportion of the broken glass area.

[0079] Table 2 Performance test data of the composite glass protection films for flexible folding screens in Examples 1-10 and Comparative Example 1

[0080] Referring to Table 2 and combining Examples 1 and Comparative Example 1, it can be seen that a large number of bubbles can be formed in the OCA adhesive layer of the present application by ultrasonic cavitation. The nano-silica wrapped by these bubbles forms a core-shell structure with the molten hydroxyacrylic resin, with nano-silica as the core and hydroxyacrylic resin as the shell. At the same time, the nano-silica with cations on the surface and the hydroxyacrylic resin promote the generation of this core-shell structure through electrostatic interaction, realizing the uniform dispersion of nano-silica particles in the acrylic resin polymer, improving the elasticity of the acrylic OCA optical adhesive, avoiding defects such as stress corrosion, delamination, cracking and fatigue in the folding screen, and increasing the service life of the protection film.

[0081] Referring to Table 2 and combining Examples 2, 4 and 5, it can be seen that the protection films formed by using the self-made linear hydroxyacrylic resin and network hydroxyacrylic resin in the present application have better bending resistance than the protection films formed by the commercially available hydroxyacrylic resin, increasing the service life of the protection film. This is because the prepared linear hydroxyacrylic resin has the characteristic of high viscoelasticity, which can further improve the elasticity of the acrylic resin. And the network hydroxyacrylic resin obtained on the basis of the linear hydroxyacrylic resin has a larger "viscoelastic effect" due to the action of the space network structure system, further improving the viscosity and elasticity of the acrylic OCA optical adhesive.

[0082] Referring to Table 2 and combining Examples 5-7 and 9, it can be seen that in the present application, the toughening agent in the epoxy resin film is a core-shell particle with organic montmorillonite as the core, rubber as the secondary outer layer, and polymer as the shell. Compared with the core-shell particles with organic montmorillonite, rubber, or rubber as the core layer and polymer as the shell as the toughening agent, it has a better toughening effect on epoxy resin, improves the impact resistance of the epoxy resin film, and further improves the impact resistance of the entire protective film. The toughening agent with rubber-coated montmorillonite as the core and polymer as the shell, on the one hand, the rubber-coated inorganic nanoparticles effectively combine rubber and montmorillonite. When montmorillonite undergoes plastic deformation, it can effectively inhibit the propagation of cracks in the matrix resin and absorb part of the energy, thus playing a toughening role; at the same time, rubber particles, as stress concentration bodies, can not only induce crazes and shear bands to absorb energy, but also terminate crazes. The rubber elastic particles can also debond from the interface and release elastic strain energy, improving the toughening and bonding strength of the material; it can not only play a toughening role of 1+1>2 for both, but also improve the flexibility of montmorillonite; on the other hand, the polymer shell can be well compatible with epoxy resin, improving the toughening effect on epoxy resin.

[0083] This specific embodiment is only an interpretation of the present application and is not a limitation thereof. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A composite glass protective sticker for a flexible folding screen, characterized in that: From top to bottom, it includes a functional base film, a first thermosetting polymer film, a UTG ultra-thin glass layer, a second thermosetting polymer film and an OCA adhesive layer; The preparation method of the OCA adhesive layer comprises the following steps: Activating the nano-silicon dioxide particles to obtain modified particles with cations on the surface; The modified particles with a mass ratio of 1:1-3 are reacted with molten hydroxy acrylic resin under the action of 600-1000W ultrasound and extruded into granules to obtain elastic acrylic masterbatch; The elastic acrylic masterbatch is mixed with a crosslinking agent and a photoinitiator to obtain an acrylic OCA optical adhesive; Applying OCA optical adhesive on one side of the release film and curing it by ultraviolet light to obtain an OCA adhesive layer; The first thermosetting polymer film and the second thermosetting polymer film are both epoxy resin films.

2. The composite glass protective sticker for a flexible folding screen according to claim 1, characterized in that: The preparation method of the modified particles is: adding nano silicon dioxide particles into a cationic surfactant aqueous solution, stirring, solid-liquid separation, washing and drying the obtained solid phase to obtain the modified particles; The mass ratio of the nano silicon dioxide particles to the cationic surfactant is 1:1-3.

3. The composite glass protective sticker for a flexible folding screen according to claim 1, characterized in that: The hydroxy acrylic resin is a linear hydroxy acrylic resin. The synthesis method of the linear hydroxy acrylic resin is as follows: 25g of methyl methacrylate, 25g of butyl acrylate, 15g of hydroxyethyl acrylate, 15g of hydroxypropyl acrylate, 10g of isooctyl acrylate and 1g of azobisisobutyronitrile are stirred and mixed until they are completely dissolved to obtain a premixed solution A, the mixed solution A is added dropwise to 30g of 90°C tetrahydrofuran, a polymerization reaction is carried out at 105°C, the temperature is kept at 3h, and then the temperature is reduced to below 70°C to obtain a linear hydroxy acrylic resin.

4. The composite glass protective sticker for a flexible folding screen according to claim 3, characterized in that: The hydroxy acrylic resin is a reticular hydroxy acrylic resin. The synthesis method of the reticular hydroxy acrylic resin is as follows: adding the linear hydroxy acrylic resin into an organic solvent, adding an isocyanate crosslinking agent, and performing a crosslinking reaction at a temperature of 30-80° C. to obtain the reticular hydroxy acrylic resin.

5. The composite glass protective sticker for a flexible folding screen according to claim 1, characterized in that: The epoxy resin film is made of the following raw materials in parts by weight: 60-70 parts of epoxy resin, 15-35 parts of toughening agent and 5-15 parts of curing agent. The toughening agent is a core-shell particle with organic montmorillonite as the core, rubber as the secondary outer layer and polymer as the shell.

6. The composite glass protective sticker for a flexible folding screen according to claim 5, characterized in that: The preparation method of the toughening agent comprises the following steps: (1) stirring 1-3 parts by weight of organic montmorillonite in 100 parts by weight of deionized water at 40-50° C. for 30-60 minutes to obtain a suspension; (2) emulsifying 20 parts by weight of an organosilicon monomer, 1-5 parts by weight of an emulsifier, 1-8 parts by weight of a silane coupling agent, 1-8 parts by weight of a vinyl silane coupling agent, and 10-20 parts by weight of deionized water for 5-10 minutes to obtain an organosilicon pre-emulsion; mixing 1-3 parts by weight of an acid catalyst and 20-25 parts by weight of deionized water to obtain an organosilicon catalyst; adding 10-40% of the organosilicon pre-emulsion and 15-25% of the organosilicon catalyst to the suspension, stirring and heating to react, and then adding the remaining organosilicon emulsion and the organosilicon catalyst to react to obtain a core layer emulsion; (3) emulsifying 1-5 parts by weight of a double bond-containing monomer, 0.1-0.5 parts by weight of an emulsifier and 1-3 parts by weight of deionized water to obtain a double bond-containing pre-emulsion; mixing 0.1-0.5 parts of an initiator and 1-20 parts of deionized water to obtain an initiating solution; (4) adding the initiating liquid into the core layer emulsion, and then adding the double bond-containing pre-emulsified liquid to react to obtain a composite emulsion, and demulsifying the composite emulsion to obtain the toughening agent.

7. The composite glass protective sticker for a flexible folding screen according to claim 6, characterized in that: In step (1), the organic montmorillonite is obtained by modifying montmorillonite with organic cations.

8. The composite glass protective sticker for a flexible folding screen according to claim 5, characterized in that: The preparation method of the epoxy resin film comprises: adding epoxy resin and curing agent into acetone solution according to a ratio and mixing to obtain a mixed solution, adding toughening agent into the mixed solution and mixing to obtain a dispersion; and coating the dispersion on a release film to obtain the epoxy resin film.

9. A method for preparing the composite glass protective film for a flexible folding screen as claimed in any one of claims 1 to 8, characterized in that: The steps include: The functional base film, the first thermosetting polymer film, the UTG ultra-thin glass and the second thermosetting polymer film are stacked in sequence from top to bottom, and the film layers are pressed together by heat pressing to form a composite layer; The OCA adhesive layer is laminated to the second thermosetting polymer film in the composite layer to form a composite glass protective film.

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