Explosion-proof glass rear cover and preparation method thereof

Abstract

The invention discloses an anti-explosion glass rear cover and an anti-explosion rear cover preparation method. According to the preparation process, impact resistance, self-repairing, anti-dazzle and anti-explosion performance are achieved through a five-layer composite structure. The impact-resistant layer adopts carboxylated carbon nanotube reinforced polyurethane to form a three-dimensional network, so that the fracture energy is remarkably improved; the self-repairing layer utilizes dynamic disulfide bonds and amino silicon oil to construct a reversible cross-linked network, and room-temperature self-repairing is achieved; the anti-dazzle layer reduces the reflectivity and keeps the light transmittance through microstructure regulation and control of nano silicon dioxide and UV resin; the explosion-proof glass body is subjected to chemical strengthening and magnetron sputtering of a TiO2 / SiO2 nano laminated layer, so that the fracture toughness is enhanced. All the layers are tightly combined through low-temperature hot pressing, a closed-loop protection system of impact resistance, self-repairing and optical control is formed, the composite material is suitable for a high-frequency use scene, and the service life of a product is remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the field of material science, specifically to the preparation of explosion-proof glass, and more particularly to an explosion-proof glass back cover and a preparation method thereof. Background Art

[0002] With the development of lightweight and functional integration of consumer electronic products, the glass back cover as a core protective component faces multiple performance challenges. Although the surface hardness of traditional explosion-proof glass back covers has been improved through chemical strengthening processes, there are still technical bottlenecks in impact resistance, durability and optical performance. First, conventional single-layer structures are difficult to effectively disperse dynamic impact energy. In falling or collision scenarios, they are prone to breakage due to stress concentration, and crack propagation is difficult to suppress. Secondly, the problem of performance degradation caused by microcracks has not yet been solved. Traditional self-healing materials are limited by repair efficiency or environmental dependence, and it is difficult to meet the long-term protection needs of high-frequency usage scenarios. In addition, anti-glare coatings generally have functional contradictions: reducing reflectivity often comes at the expense of transmittance, and insufficient surface wear resistance can easily lead to optical performance degradation. In terms of structural integrity, the interface bonding strength of multi-layer composite materials directly affects the overall reliability. Traditional processes often lead to the risk of interlayer delamination due to poor interface compatibility.

[0003] To address the aforementioned industry pain points, the present invention proposes a multi-level, synergistically reinforced explosion-proof glass back cover solution. By constructing a functional gradient system of "impact resistance-self-repairing-optical regulation," the solution innovatively integrates nano-enhancement, dynamic chemical bond exchange, and micro-nanostructure regulation technologies. Regarding mechanical reinforcement, carboxylated carbon nanotubes are used to construct a three-dimensional thermally conductive network, combined with nano-laminates deposited by magnetron sputtering to form a rigid-tough coupling structure, achieving graded dissipation of impact energy. Regarding functional continuity, a dynamically disulfide-crosslinked silicone elastomer is designed as a self-repairing carrier, autonomously repairing microcracks through a reversible bond exchange mechanism. Regarding optical performance optimization, a composite microstructure of nano-silica and UV resin is utilized to achieve a balance between low reflectivity and high transmittance, and polyether-modified polysiloxane is introduced to enhance surface wear resistance. Each functional layer is chemically bonded through modification with a silane coupling agent and a low-temperature hot pressing process, ensuring efficient transfer of interfacial loads. Ultimately, a new protective structure with impact resistance, self-repairing, anti-glare, and wear resistance is formed, providing key technical support for the reliability upgrade of consumer electronic products. Summary of the Invention

[0004] In response to the above problems, the present invention provides an explosion-proof glass back cover and a preparation method thereof. The specific preparation steps are as follows:

[0005] S1. Preparation of impact-resistant layer: 3-4 g of carboxylated carbon nanotubes were added to 120-150 ml of DMF solvent, and pre-dispersed using a high-speed disperser at a speed of 15,000 r / min for 30 min. After pre-dispersion, the mixture was added to 80-100 g of polyurethane prepolymer, and high-speed shearing was performed at 15,000 rpm for 30 min, followed by ultrasonication at 40 kHz for 1 h. The dispersed prepolymer was coated on a PET release film using a precision doctor blade coater at a coating speed of 2 m / min and a gap of 45-55 μm. The film was cured at 100° C. for 30 min and then peeled off to obtain an impact-resistant layer. A reinforced network structure was formed by dispersing the carboxylated carbon nanotubes in the polyurethane prepolymer. High-speed shearing and ultrasonic synergistic treatment were used to ensure uniform dispersion of the nanotubes. The film was coated and cured to form an impact-resistant layer with high fracture energy, the main function of which was to absorb and disperse external impact energy.

[0006] S2. Preparation of self-repairing layer: 45-55g of dynamic disulfide bond monomer was mixed with 50-70g of amino silicone oil, and the mixture was reacted at 60°C under nitrogen protection for 3-5h. After the reaction, 0.3-0.7g of platinum catalyst was added and vacuum degassing was carried out in a vacuum planetary mixer at a speed of 2000rpm and a vacuum degree of -0.1MPa for 10-20min. After the reaction, the mixture was cast into a film in a casting machine at a speed of 1m / min and a film thickness of 28-32μm. The dynamic disulfide bond monomer and amino silicone oil were reacted at 60°C for 3-5h to form a reversible cross-linked network, and the platinum catalyst was added to promote sulfur bond exchange. This layer has room temperature self-repairing function, which can autonomously repair microcracks after damage and extend the service life of the product.

[0007] S3. Synthesis of polyether-modified polysiloxane: Using the telomerization method, add 2.0-2.4 g of dimethyl carbonate, 0.22-0.24 g of high-hydrogen silicone oil, and 0.04-0.06 g of hexamethyldisiloxane to a reaction kettle. Add 0.1 ml of 98% concentrated sulfuric acid as a catalyst. React at 60-65°C for 2-3 hours, then cool to room temperature. Neutralize with 3 ml of 10% aqueous sodium bicarbonate solution, and filter. The treated product is then heated to 100-110° C., and low-boiling substances are removed by vacuum distillation for 1-2 hours to obtain low-hydrogen silicone oil. 2.1-2.5 g of low-hydrogen silicone oil and 1.8-2.1 g of allyl polyoxyethylene polyoxypropylene ether are sequentially added to a four-necked flask equipped with a stirrer and a thermometer, and nitrogen is introduced and stirred for 5-10 minutes. The temperature is then raised to 80-90° C., and 10-20 μg / g (calculated as platinum mass, catalyst / total system mass, the total system mass being the sum of the mass of the low-hydrogen silicone oil and the allyl polyoxyethylene polyoxypropylene ether) of chloroplatinic acid catalyst is added. The reaction is carried out for 0.5-1.5 hours, and the temperature is cooled to room temperature to obtain polyether-modified polysiloxane.

[0008] S4, anti-glare layer compounding: in a light-proof environment, 20g of nano-silicon dioxide was gradually added to 80g of UV-curable acrylic resin in five portions at a rate of 4g each, stirring evenly after each addition before adding the next portion. After the addition was complete, ultrasonic compounding was performed at 40kHz for 30min to form a uniform slurry; 0.8-1.2g of the polyether-modified polysiloxane prepared in step S3 was slowly added to the premixed slurry under low-speed stirring conditions of 200-500rpm, and stirring was continued for 5-10 minutes until the system was uniform and free of shrinkage cavities; the premixed slurry was injected into the chute of the coating machine, the liquid level was kept constant, and single-sided coating was performed on the surface of the impact-resistant layer obtained in step S1 with a thickness of 25-35μm; after coating, the substrate was immediately placed in a UV curing box for curing at a light intensity of 1000mJ / cm 2 , the exposure time is 30s, that is, the anti-glare layer is composited to the impact-resistant layer; nano-silicon dioxide is dispersed in the UV resin to form an anti-glare coating, and the haze is reduced while maintaining the light transmittance by controlling the surface roughness. The main function is to reduce light reflection and improve display clarity; at the same time, the addition of nano-silicon dioxide can also improve the coating uniformity and enhance wear resistance;

[0009] S5. Immerse 0.5 mm thick aluminosilicate glass in 75 wt% KNO3 and 25 wt% NaNO3 molten salt and chemically strengthen it at 400℃±5℃ for 4 hours to form a strengthening layer. Then, magnetron sputtering is used on one side of the strengthening layer to form a 5×10 -6 Under a Torr vacuum, TiO2 and SiO2 were sputtered alternately at 150W RF power and 100W RF power, forming a nano-toughened laminate with a total thickness of 500nm. This resulted in an explosion-proof glass back cover with a nano-toughened laminate. Chemical strengthening formed a compressive stress layer on the glass surface, and magnetron sputtering of the TiO2 / SiO2 nano-laminate enhanced the fracture toughness, provided rigid support, and inhibited crack propagation.

[0010] S6, soak the explosion-proof glass back cover body with nano-toughened laminate prepared in step S5 in an ethanol solution containing 1wt% KH-550 for 10 minutes, take it out and rinse it with deionized water; laminate the anti-glare layer and impact-resistant layer compounded in step S4, the rinsed explosion-proof glass back cover body with nano-toughened laminate and the self-repairing layer prepared in step S2 in a clean room, with the anti-glare layer facing outwards, and the self-repairing layer between the impact-resistant layer and the nano-toughened laminate of the explosion-proof glass back cover body, that is, the anti-glare layer, impact-resistant layer, self-repairing layer arranged in sequence from outside to inside. Layer, nano-toughened laminate and explosion-proof glass back cover body; hot pressing and compounding are carried out in a hot press, the heating temperature is set to 90℃, and pre-pressing is carried out for 20 to 40s in the initial stage with a pressure of 0.3MPa to eliminate the gap between layers, and then the pressure is 0.8MPa full pressing and maintained for 3min. After the end, it is cooled to below 60℃ and the mold is opened to obtain an explosion-proof glass back cover with self-repairing and anti-glare. KH-550 silane coupling agent is used to treat the glass surface, and low-temperature hot pressing at 90℃ is used to achieve close bonding of various functional layers without damaging the self-repairing function, ensuring strong interface bonding of the multi-layer structure and overall performance integrity.

[0011] Preferably, in step S1, the amount of carboxylated carbon nanotubes used is 3.5 g, and the amount of DMF solvent used is 135 ml.

[0012] Preferably, in step S2, 50 g of dynamic disulfide bond monomer is mixed with 60 g of amino silicone oil, and reacted at 60° C. for 4 h under nitrogen protection; after the reaction, 0.5 g of platinum catalyst is added.

[0013] Preferably: in step S3, 2.2 g of dimethyl carbonate, 0.23 g of high hydrogen silicone oil and 0.05 g of hexamethyldisiloxane are taken; 2.3 g of low hydrogen silicone oil and 1.91 g of allyl polyoxyethylene polyoxypropylene ether are added to the polyether-modified polysiloxane in sequence.

[0014] Preferably, in step S4, 20 g of nano-silica is gradually added to 80 g of UV-curable acrylic resin in five portions, and 1.0 g of polyether-modified polysiloxane is added.

[0015] Preferably, the chemical strengthening time in step S5 is 5 hours.

[0016] Preferably, the pre-pressing time in step S6 is 30s.

[0017] By adopting the above technical solution, the technical progress achieved by the present invention is:

[0018] 1. This invention achieves breakthrough impact resistance through the synergistic effect of carboxylated carbon nanotube (CNT)-reinforced polyurethane composites and nano-toughened laminates. The impact-resistant layer utilizes carboxylated CNTs dispersed in a polyurethane prepolymer. High-speed shear and ultrasonic treatments are used to form a three-dimensional network structure, enhancing the material's fracture energy. Simultaneously, a 500nm thick alternating sputtered layer of TiO2 / SiO2 is deposited on the glass substrate. The high modulus of TiO2 and the toughness of SiO2 are synergistically utilized to enhance crack propagation resistance through interfacial stress gradient design.

[0019] 2. The anti-glare layer optimizes optical performance through microstructural regulation of nano-silica and UV acrylic resin. 20wt% nano-SiO2 (Evonik AEROSIL 200) is dispersed in UV resin and spin-coated to form a wet film. After UV curing, a moth-eye structure forms on the surface, which reduces specular reflectivity through light scattering while maintaining visible light transmittance. The slight difference between the high refractive index of nano-SiO2 and the resin matrix, as well as the subwavelength characteristics of the surface micro-nanostructure, synergistically suppress Fresnel reflection and wide-angle glare. This layer and the impact-resistant layer are designed with refractive index matching to minimize overall light transmission loss, achieving compatibility between optical protection and mechanical properties.

[0020] 3. The self-healing ability stems from the molecular structure design of the dynamic disulfide bond silicone elastomer. A dynamic cross-linking network is formed with dynamic disulfide bond monomers and amino silicone oil, and a platinum catalyst is added to promote the reversible exchange of sulfur bonds. When the material is damaged, the sulfur bonds break and recombine under stress, achieving self-repair at room temperature within 24 hours. The synergy between this layer and the impact-resistant layer is reflected in the following: the self-healing layer is located in the middle layer, which can not only dissipate impact energy through the dynamic network, but also repair microcracks transmitted by the upper anti-glare layer. In terms of technology, low-temperature hot pressing at 90°C avoids damage to the sulfur bond network, ensuring that the functional layer remains active during the composite process, and realizing a full life cycle protection closed loop of "impact resistance-self-repair-optical regulation".

[0021] 4. The present invention achieves a breakthrough improvement in impact resistance through the synergistic effect of carboxylated carbon nanotubes (CNTs) reinforced polyurethane composites and nano-toughened laminates. Carboxylated CNTs form a three-dimensional heat-conducting network in the polyurethane matrix, effectively transmitting and dissipating impact energy. At the same time, the microphase separation structure of polyurethane gives the material excellent toughness recovery ability. The nano-toughened laminate constructs a modulus gradient interface through the alternating deposition of TiO2 and SiO2, which not only provides rigid support but also inhibits crack propagation. Under the synergistic effect of the two, the impact energy is dissipated in stages: the CNT network absorbs the initial energy, and the nano-laminate further consumes the remaining energy through plastic deformation and crack deflection. In addition, the silane coupling agent optimizes the interface bonding, the self-healing layer buffers stress concentration, and the gradient modulus design reduces the risk of interface delamination. Ultimately, the composite structure shows significant advantages in impact resistance, fatigue resistance and transmittance retention, providing a full-scale protection solution for the design of high-performance explosion-proof glass back covers.

[0022] 5. The nano-silica, UV-curable acrylic resin, and polyether-modified polysiloxane in the anti-glare layer of this invention achieve breakthrough wear resistance through a "hard-tough-lubricious" synergistic mechanism: the nano-silica creates a three-dimensional hard skeleton to disperse stress, the UV resin provides a tough substrate to absorb energy, and the polyether-modified polysiloxane forms a lubricating layer on the surface and strengthens interfacial bonding. The combination of these three elements increases the pencil hardness of the coating, reduces the coefficient of friction, and improves the wear resistance of the steel wool, significantly extending the lifespan of high-frequency applications such as touch screens. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A bar chart comparing load peak data in impact resistance test data of explosion-proof glass back covers prepared in Example 1 of the present invention and Comparative Examples 1 to 3;

[0025] Figure 2 This is a bar graph comparing the anti-glare performance test data of Example 2 of the present invention and Comparative Examples 4-5;

[0026] Figure 3 The double Y-axis bar-dot line graph is a graph of the friction coefficient and the mass loss after wear obtained from the wear resistance test of Example 3 of the present invention and Comparative Examples 6 to 8. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] In the present invention, carboxylated carbon nanotubes (C139847) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; polyurethane prepolymer (MDI series) was purchased from Zibo Hengjiu Polyurethane Technology Co., Ltd.; dynamic disulfide bond monomer was purchased from Xi'an Qiyue Biotechnology Co., Ltd.; amino silicone oil (ultra-smooth amino silicone oil) was purchased from Ningbo Runhe Chemical Industry Co., Ltd.; platinum catalyst was purchased from Dongguan Kebei Silicone Material Co., Ltd.; nanosilica (VK-SP20) was purchased from Shanghai Xiangtian Nanomaterial Co., Ltd.; UV-curable acrylic resin (RS-875E, viscosity 8000 mPa·s) was purchased from Shenzhen Jinfengyuan Polymer Materials Co., Ltd.; aluminosilicate glass was purchased from Nantong Zhenhua Optoelectronics Co., Ltd.; and allyl polyoxyethylene polyoxypropylene ether (9041-33-2) was purchased from Zhejiang Lukean Chemical Co., Ltd.

[0029] Example 1

[0030] This example illustrates that a breakthrough in impact resistance is achieved through the synergistic effect of carboxylated carbon nanotubes (CNTs) reinforced polyurethane composites and nano-toughened laminates, making the impact resistance of the present invention even stronger;

[0031] The specific implementation steps are as follows:

[0032] S1. Preparation of impact-resistant layer: 3.5 g of carboxylated carbon nanotubes were added to 135 ml of DMF solvent and pre-dispersed using a high-speed disperser at a speed of 15,000 rpm for 30 min. After pre-dispersion, the mixture was added to 90 g of polyurethane prepolymer, and high-speed shearing was performed at 15,000 rpm for 30 min, followed by ultrasonication at 40 kHz for 1 h. The dispersed prepolymer was coated on a PET release film using a precision doctor blade coater at a coating speed of 2 m / min and a gap of 50 μm. The film was cured at 100° C. for 30 min and then peeled off to obtain the impact-resistant layer.

[0033] S2. Preparation of self-healing layer: 50 g of dynamic disulfide bond monomer was mixed with 60 g of amino silicone oil, and the mixture was reacted at 60° C. under nitrogen protection for 4 h. After the reaction, 0.5 g of platinum catalyst was added and vacuum degassing was carried out in a vacuum planetary mixer at a speed of 2000 rpm and a vacuum degree of -0.1 MPa for 15 min. After the reaction, the mixture was cast into a film in a casting machine at a speed of 1 m / min and a film thickness of 30 μm.

[0034] S3. Synthesis of polyether-modified polysiloxane: 2.2g of dimethyl carbonate, 0.23g of high-hydrogen silicone oil and 0.05g of hexamethyldisiloxane were added to a reactor by a telomerization method, 0.1ml of 98% concentrated sulfuric acid was added as a catalyst, and the mixture was reacted at 63°C for 3h, and then cooled to room temperature. 3ml of 10% sodium bicarbonate aqueous solution was added for neutralization, and the mixture was filtered. The treated product was then heated to 100°C and distilled using a vacuum pump for 1.5h to remove low-boiling substances to obtain low-hydrogen silicone oil; 2.3g of low-hydrogen silicone oil and 1.91g of allyl polyoxyethylene polyoxypropylene ether were added to a four-necked flask equipped with a stirrer and a thermometer, nitrogen was introduced, and stirred for 10min, then the temperature was raised to 90°C, 15μg / g of chloroplatinic acid catalyst was added, the mixture was reacted for 1.5h, and the temperature was cooled to room temperature to obtain polyether-modified polysiloxane;

[0035] S4, anti-glare layer compounding: in a light-proof environment, 20g of nano-silicon dioxide was gradually added to 80g of UV-curable acrylic resin in five portions at a rate of 4g each, stirring evenly after each addition before adding the next portion. After the addition was complete, ultrasonic compounding was performed at 40kHz for 30min to form a uniform slurry; 1.0g of the polyether-modified polysiloxane prepared in step S3 was slowly added to the premixed slurry under low-speed stirring at 500rpm, and stirring was continued for 10 minutes until the system was uniform and free of shrinkage cavities; the premixed slurry was injected into the chute of the coating machine, the liquid level was kept constant, and the impact-resistant layer obtained in step S1 was coated on one side with a thickness of 30μm; after coating, the substrate was immediately placed in a UV curing box for curing at a light intensity of 1000mJ / cm 2 , the exposure time is 30s, that is, the anti-glare layer is composited into the impact-resistant layer;

[0036] S5. Immerse 0.5 mm thick aluminosilicate glass in 75 wt% KNO3 and 25 wt% NaNO3 molten salt and chemically strengthen it at 400℃±5℃ for 5 hours to form a strengthening layer. Then, magnetron sputtering is used on one side of the strengthening layer to form a 5×10 -6 Under a Torr vacuum, 10 layers of TiO2 and SiO2 were alternately deposited at 150W RF power and 100W RF power, forming a nano-toughened laminate with a total thickness of 500nm, thus obtaining a tough explosion-proof glass back cover body.

[0037] S6. Soak the explosion-proof glass back cover body prepared in step S5 in an ethanol solution containing 1wt% KH-550 for 10 minutes, take it out and rinse it with deionized water; stack the anti-glare layer and impact-resistant layer compounded in step S4 with the rinsed explosion-proof glass back cover body and the self-repairing layer prepared in step S2 in a clean room, with the anti-glare layer facing outward and the self-repairing layer between the impact-resistant layer and the explosion-proof glass back cover body; perform hot pressing and compounding in a hot press, set the heating temperature to 90°C, pre-press for 30s in the initial stage, and the pressure is 0.3MPa to eliminate the gap between the layers, and then fully press with a pressure of 0.8MPa, and maintain for 3 minutes. After cooling to below 60°C, open the mold to obtain an explosion-proof glass back cover with self-repairing anti-glare.

[0038] Comparative Example 1: In step S1, ordinary carbon nanotubes were used instead of carboxylated carbon nanotubes, and the other steps were the same as those in Example 1;

[0039] Comparative Example 2: In step S1, pure polyurethane was used instead of the reinforced polyurethane composite material, and the other steps were the same as those in Example 1;

[0040] Comparative Example 3: In step S5, a single nanolayer is used instead of the alternating layers (i.e., a 500 nm nanolayer is spread at a time), and the other steps are the same as in Example 1;

[0041] Among them, ordinary carbon nanotubes (C121252) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; pure polyurethane was purchased from Wanhua Chemical.

[0042] Impact resistance test:

[0043] Test method: The explosion-proof glass back covers prepared in Example 1 and Comparative Examples 1 to 3 were cut into 95 mm × 95 mm specimens, and the impact resistance was tested using a Dynatup 92 material impact tester produced by INSIRON, USA.

[0044] In the experiment, the mass of the hammer's punch was kept constant at 5.7806 kg, and the impact speed was set as needed to obtain different hammer drop heights. According to the law of conservation of energy, the instantaneous maximum impact kinetic energy of the hammer is Where m is the mass of the falling weight, v is i is the instantaneous velocity of the drop hammer impact. The energy absorbed when the material is damaged is Where, v f is the instantaneous maximum reverse speed of the falling hammer after it is rebounded by the plate; It is the kinetic energy gained by the falling hammer due to the release of elastic deformation energy of the laminate after impact. During the impact process, the impact load calculation formula is: Where V(t) is the velocity versus time curve. The shape of the punch is bullet-shaped.

[0045] The explosion-proof glass back covers prepared in Example 1 and Comparative Examples 1 to 3 were subjected to low-speed impact tests, with 5 parallel samples tested in each group. The peak load, displacement at the peak, and peak time data were collected and recorded in Table 1.

[0046] Table 1 Impact resistance test data of Example 1 and Comparative Examples 1 to 3

[0047] Energy at peak value / J Peak load / KN Peak displacement / mm Peak time / s Example 1 3.21±0.35 1.21±0.12 4.89±0.34 6.21±0.83 Comparative Example 1 2.64±0.28 0.95±0.08 4.23±0.38 5.12±0.71 Comparative Example 2 2.24±0.36 0.87±0.07 4.15±0.31 4.96±0.74 Comparative Example 3 2.56±0.22 0.92±0.07 3.87±0.26 4.56±0.67

[0048] It can be seen from Table 1 that all parameters of Example 1 are greater than those of Comparative Examples 1 to 3, and the load peak is the highest, indicating that it has the best energy absorption; at the same time, the displacement at the peak is the largest, indicating that the toughness is optimal, and the peak time is prolonged, indicating that its strength is high and the impact resistance is the best.

[0049] Example 2

[0050] This embodiment illustrates that the present invention optimizes optical performance by controlling the microstructure of nano-silica and UV acrylic resin, thereby achieving a good anti-glare effect.

[0051] The specific implementation steps are as follows:

[0052] S1. Preparation of impact-resistant layer: 3 g of carboxylated carbon nanotubes were added to 120 ml of DMF solvent and pre-dispersed using a high-speed disperser at a speed of 15,000 rpm for 30 min. After pre-dispersion, the mixture was added to 80 g of polyurethane prepolymer, and high-speed shearing was performed at 15,000 rpm for 30 min, followed by ultrasonication at 40 kHz for 1 h. The dispersed prepolymer was coated on a PET release film using a precision doctor blade coater at a coating speed of 2 m / min and a gap of 45 μm. The film was cured at 100° C. for 30 min and then peeled off to obtain the impact-resistant layer.

[0053] S2. Preparation of self-healing layer: 45 g of dynamic disulfide bond monomer was mixed with 50 g of amino silicone oil, and the mixture was reacted at 60°C under nitrogen protection for 3 h. After the reaction, 0.3 g of platinum catalyst was added and vacuum degassing was carried out in a vacuum planetary mixer at a speed of 2000 rpm and a vacuum degree of -0.1 MPa for 10 min. After the reaction, the mixture was cast into a film in a casting machine at a speed of 1 m / min and a film thickness of 28 μm.

[0054] S3. Synthesis of polyether-modified polysiloxane: 2.0 g of dimethyl carbonate, 0.22 g of high hydrogen silicone oil and 0.04 g of hexamethyldisiloxane were added to a reactor by telomerization, 0.1 ml of 98% concentrated sulfuric acid was added as a catalyst, and the mixture was reacted at 65 ° C for 3 hours, and then cooled to room temperature. 3 ml of 10% sodium bicarbonate aqueous solution was added for neutralization, and the mixture was filtered. The treated product was then heated to 100 ° C, and low-boiling substances were removed by vacuum distillation for 1 hour to obtain low hydrogen silicone oil; 2.1 g of low hydrogen silicone oil and 1.8 g of allyl polyoxyethylene polyoxypropylene ether were added to a four-necked flask equipped with a stirrer and a thermometer, and nitrogen was introduced and stirred for 10 minutes. The temperature was then raised to 90 ° C, 20 μg / g of chloroplatinic acid catalyst was added, the mixture was reacted for 1.5 hours, and the mixture was cooled to room temperature to obtain polyether-modified polysiloxane;

[0055] S4, anti-glare layer compounding: in a light-proof environment, 20g of nano-silicon dioxide was gradually added to 80g of UV-curable acrylic resin in five portions at a rate of 4g each, stirring evenly after each addition before adding the next portion. After the addition was complete, ultrasonic compounding was performed at 40kHz for 30min to form a uniform slurry; 0.8g of the polyether-modified polysiloxane prepared in step S3 was slowly added to the premixed slurry under low-speed stirring at 200rpm, and stirring was continued for 5 minutes until the system was uniform and free of shrinkage cavities; the premixed slurry was injected into the chute of the coating machine, the liquid level was kept constant, and the impact-resistant layer obtained in step S1 was coated on one side with a thickness of 25μm; after coating, the substrate was immediately placed in a UV curing box for curing at a light intensity of 1000mJ / cm 2 , the exposure time is 30s, that is, the anti-glare layer is composited into the impact-resistant layer;

[0056] S5. Immerse 0.5 mm thick aluminosilicate glass in 75 wt% KNO3 and 25 wt% NaNO3 molten salt and chemically strengthen it at 400℃±5℃ for 4 hours to form a strengthening layer. Then, magnetron sputtering is used on one side of the strengthening layer to form a 5×10 -6 Under a Torr vacuum, 10 layers of TiO2 and SiO2 were alternately deposited at 150W RF power and 100W RF power, forming a nano-toughened laminate with a total thickness of 500nm, thus obtaining a tough explosion-proof glass back cover body.

[0057] S6. Soak the explosion-proof glass back cover body prepared in step S5 in an ethanol solution containing 1wt% KH-550 for 10 minutes, take it out and rinse it with deionized water; stack the anti-glare layer and impact-resistant layer compounded in step S4 with the rinsed explosion-proof glass back cover body and the self-repairing layer prepared in step S2 in a clean room, with the anti-glare layer facing outward and the self-repairing layer between the impact-resistant layer and the explosion-proof glass back cover body; perform hot pressing and compounding in a hot press, set the heating temperature to 90°C, perform pre-pressing for 20s in the initial stage, and the pressure is 0.3MPa to eliminate the gap between the layers, and then the pressure is 0.8MPa full pressure, maintained for 3min, and after cooling to below 60°C, open the mold to obtain an explosion-proof glass back cover with self-repairing anti-glare.

[0058] Comparative Example 4: In step S4, nano-zirconia was used instead of nano-silicon dioxide, and the other steps were the same as those in Example 2;

[0059] Comparative Example 5: In step S4, epoxy acrylate was used instead of UV curing acrylic resin, and the other steps were the same as those in Example 2;

[0060] Among them, nano-HfO2 was purchased from Suzhou Kaifa New Material Technology Co., Ltd. (DK-HfO2-001); epoxy acrylate (L-6131) was purchased from Lankelu New Material Technology Co., Ltd.

[0061] Anti-glare performance test:

[0062] 1. Transmittance measurement:

[0063] Test Method: The light transmittance of the explosion-proof glass back covers obtained in Example 2 and Comparative Examples 4-5 was measured according to the national standard GB / T 2410-80, "Test Method for Light Transmittance and Haze of Transparent Plastics." The total luminous flux of the incident light beam is Φ1. The total transmitted luminous flux of Φ1 that passes through the test sample is Φ2. The tiny portion of Φ2 that deviates outside the divergence angle is the scattered incident luminous flux Φ3. The scattered luminous flux of the instrument and sample is Φ4. Each sample was tested five times and the average value was obtained.

[0064] The transmittance τ is calculated as follows:

[0065] τ=(Φ2 / Ф1)×100%

[0066] 2. Haze determination:

[0067] The haze of the anti-glare layers obtained in Example 2 and Comparative Examples 4-5 was measured according to the national standard GB / T 2410-80 "Test method for light transmittance and haze of transparent plastics." The total luminous flux of the incident light beam is Φ1, the total transmitted luminous flux of Φ1 that passes through the test sample is Φ2, the extremely small portion of the luminous flux in Φ2 that deviates outside the divergence angle is the scattered incident luminous flux Φ3, and the scattered luminous flux of the instrument and the sample is Φ4.

[0068] The calculation formula for haze H is:

[0069] H=(Ф4 / Φ2-Φ3 / Φ1)×100%

[0070] 3.60° gloss measurement:

[0071] Use a gloss meter to measure the gloss of the paint film surface, and measure the luminous flux Φ of the reflected light beam passing through the specified light hole after the 60° incident light is irradiated on the anti-glare surface to be tested s Luminous flux Φ of the light beam reflected by the standard plate under the same conditions 0s The mathematical expression of the ratio is:

[0072] G s (θ)=Ф s / Ф 0s ×100%

[0073] Where: G s ——Gloss value of the paint film being tested;

[0074] θ – angle of incident light;

[0075] Ф s ——The luminous flux reflected by the paint film being measured;

[0076] Ф 0s ——Luminous flux reflected by the standard plate.

[0077] The experimental data obtained are recorded in Table 2;

[0078] Table 2 Anti-glare performance test data of Example 2 and Comparative Examples 4-5

[0079]

[0080] As can be seen from Table 2, the total light transmittance of the three samples all meet the standard requirements, and the difference between the three is not large. The haze and 60° glossiness of the explosion-proof glass prepared in Example 2 are closer to the standard values, which shows that the explosion-proof glass prepared in Example 2 has the best anti-glare performance. Furthermore, the microstructure regulation of nano-silica and UV acrylic resin can achieve optical performance optimization and achieve good anti-glare effect.

[0081] Example 3:

[0082] This embodiment illustrates that the nano-silica, UV-curable acrylic resin, and polyether-modified polysiloxane in the anti-glare layer of the present invention achieve a breakthrough in wear resistance through a "hard-tough-lubricated" synergistic mechanism.

[0083] The specific implementation steps are as follows:

[0084] S1. Preparation of impact-resistant layer: 4 g of carboxylated carbon nanotubes were added to 150 ml of DMF solvent and pre-dispersed using a high-speed disperser at a speed of 15,000 rpm for 30 min. After pre-dispersion, the mixture was added to 100 g of polyurethane prepolymer, and high-speed shearing was carried out at 15,000 rpm for 30 min, followed by ultrasonication at 40 kHz for 1 h. The dispersed prepolymer was coated on a PET release film using a precision doctor blade coater at a coating speed of 2 m / min and a gap of 55 μm. The film was cured at 100° C. for 30 min and then peeled off to obtain the impact-resistant layer.

[0085] S2. Preparation of self-healing layer: 55 g of dynamic disulfide bond monomer was mixed with 70 g of amino silicone oil, and the mixture was reacted at 60° C. under nitrogen protection for 5 h. After the reaction, 0.7 g of platinum catalyst was added and vacuum degassing was carried out in a vacuum planetary mixer at a speed of 2000 rpm and a vacuum degree of -0.1 MPa for 20 min. After the reaction, the mixture was cast into a film in a casting machine at a speed of 1 m / min and a film thickness of 32 μm.

[0086] S3. Synthesis of polyether-modified polysiloxane: 2.4g of dimethyl carbonate, 0.24g of high hydrogen silicone oil and 0.06g of hexamethyldisiloxane were added to a reactor by telomerization, 0.1ml of 98% concentrated sulfuric acid was added as a catalyst, and the mixture was reacted at 60°C for 3h, and then cooled to room temperature. 3ml of 10% sodium bicarbonate aqueous solution was added for neutralization, and the mixture was filtered. The treated product was then heated to 110°C and distilled using a vacuum pump for 2h to remove low-boiling substances to obtain low hydrogen silicone oil; 2.5g of low hydrogen silicone oil and 2.1g of allyl polyoxyethylene polyoxypropylene ether were added to a four-necked flask equipped with a stirrer and a thermometer, nitrogen was introduced, and stirred for 10min, then the temperature was raised to 90°C, 20μg / g of chloroplatinic acid catalyst was added, the mixture was reacted for 1.5h, and the temperature was cooled to room temperature to obtain polyether-modified polysiloxane;

[0087] S4, anti-glare layer compounding: in a light-proof environment, 20g of nano-silicon dioxide was gradually added to 80g of UV-curable acrylic resin in five portions at a rate of 4g each, stirring evenly after each addition before adding the next portion. After the addition was complete, ultrasonic compounding was performed at 40kHz for 30min to form a uniform slurry; 1.2g of the polyether-modified polysiloxane prepared in step S3 was slowly added to the premixed slurry under low-speed stirring at 500rpm, and stirring was continued for 10 minutes until the system was uniform and free of shrinkage cavities; the premixed slurry was injected into the chute of the coating machine, the liquid level was kept constant, and the impact-resistant layer obtained in step S1 was coated on one side with a thickness of 35μm; after coating, the substrate was immediately placed in a UV curing box for curing at a light intensity of 1000mJ / cm 2 , the exposure time is 30s, that is, the anti-glare layer is composited into the impact-resistant layer;

[0088] S5. Immerse 0.5 mm thick aluminosilicate glass in 75 wt% KNO3 and 25 wt% NaNO3 molten salt and chemically strengthen it at 400℃±5℃ for 4 hours to form a strengthening layer. Then, magnetron sputtering is used on one side of the strengthening layer to form a 5×10 -6 Under a Torr vacuum, 10 layers of TiO2 and SiO2 were alternately deposited at 150W RF power and 100W RF power, forming a nano-toughened laminate with a total thickness of 500nm, thus obtaining a tough explosion-proof glass back cover body.

[0089] S6. Soak the explosion-proof glass back cover body prepared in step S5 in an ethanol solution containing 1wt% KH-550 for 10 minutes, take it out and rinse it with deionized water; stack the anti-glare layer and impact-resistant layer compounded in step S4 with the rinsed explosion-proof glass back cover body and the self-repairing layer prepared in step S2 in a clean room, with the anti-glare layer facing outward and the self-repairing layer between the impact-resistant layer and the explosion-proof glass back cover body; perform hot pressing and compounding in a hot press, set the heating temperature to 90°C, perform pre-pressing for 40s in the initial stage, and the pressure is 0.3MPa to eliminate the gap between the layers, and then fully press with a pressure of 0.8MPa, maintain for 3min, and cool to below 60°C after the end, then open the mold to obtain an explosion-proof glass back cover with self-repairing anti-glare.

[0090] Comparative Example 6: In step S4, an equal amount of aluminum oxide was used instead of silicon dioxide, and the other steps were the same as those in Example 3;

[0091] Comparative Example 7: In step S4, an equal amount of high cross-linking density epoxy resin was used instead of the UV curing acrylic resin, and the other steps were the same as those in Example 3;

[0092] Comparative Example 8: In step S4, an equal amount of ordinary polydimethylsiloxane was used instead of polyether-modified polysiloxane, and the other steps were the same as those in Example 3;

[0093] Among them, alumina (XT-0806-8-1) was purchased from Shanghai Xiangtian Nanomaterials Co., Ltd.; high cross-linking density epoxy resin (E-03) was purchased from Shenzhen Jinfengyuan Polymer Materials Co., Ltd.;

[0094] Wear resistance test:

[0095] The wear resistance of the anti-glare layers prepared in Example 3 and Comparative Examples 6 to 8 was tested according to GB / T 3960-2016 “Test methods for sliding friction and wear of plastics”;

[0096] Test sample: The anti-glare layer with an anti-impact layer obtained in step 4 of Example 3 and Comparative Examples 6 to 8 was cut into a standard size of 30 mm×7 mm. During the test, the anti-glare layer served as the test surface.

[0097] Test method: Install the specimen in the testing machine, place it above the test ring, and apply a load. The specimen remains stationary while the test ring rotates at 200 rpm. The test lasts 2 hours and the load is 196 N. Calculate the wear mass loss and coefficient of friction using the following formula.

[0098] (1) Wear mass loss Δm = m1 - m2; where:

[0099] Δm is the mass wear, in milligrams (mg);

[0100] m1 is the mass of the sample before the test, in milligrams (mg);

[0101] m2 is the mass of the sample after the test, in milligrams (mg).

[0102] (2) Friction coefficient μ = M / (r·F)

[0103] Where:

[0104] M is the friction torque, in Newton centimeters (N·cm);

[0105] r is the radius of the ring, in centimeters (cm);

[0106] F is the test load, in Newton (N).

[0107] Repeat 3 times and take the average value of the final result. The experimental data are recorded in Table 3;

[0108] Table 3 Wear resistance test results

[0109]

[0110]

[0111] It can be seen from the experimental data that when nano-silica, UV-curing acrylic resin and polyether-modified polysiloxane are present in the anti-glare layer at the same time, it has a good synergistic wear-resistant effect, the smallest friction coefficient, the least wear loss mass, and the best wear resistance.

Claims

1. An explosion-proof glass back cover, characterized in that: It includes an anti-glare layer, an anti-impact layer, a self-repairing layer, a nano-toughened laminate and an explosion-proof glass back cover body arranged in sequence from the outside to the inside; The impact-resistant layer was prepared by adding 3 to 4 g of carboxylated carbon nanotubes to 120 to 150 ml of DMF solvent, pre-dispersing the prepolymer using a high-speed disperser at a speed of 15,000 r / min for 30 minutes, adding the pre-dispersed prepolymer to 80 to 100 g of polyurethane prepolymer, shearing the prepolymer at 15,000 rpm for 30 minutes, and then ultrasonicating the prepolymer at 40 kHz for 1 hour; coating the dispersed prepolymer on a PET release film using a precision doctor blade coater at a coating speed of 2 m / min and a gap of 45 to 55 μm; and curing the prepolymer at 100° C. for 30 minutes before peeling the prepolymer off to obtain the impact-resistant layer.

2. The explosion-proof glass back cover according to claim 1, characterized in that: The preparation method of the self-healing layer is as follows: 45 to 55 g of dynamic disulfide bond monomer is mixed with 50 to 70 g of amino silicone oil, and the mixture is reacted at 60°C under nitrogen gas protection for 3 to 5 hours; after the reaction, 0.3 to 0.7 g of platinum catalyst is added and vacuum degassing is carried out in a vacuum planetary mixer at a speed of 2000 rpm and a vacuum degree of -0.1 MPa. The reaction is carried out for 10 to 20 minutes. After the reaction is completed, the film is cast in a casting machine at a speed of 1 m / min and the film thickness is set to 28 to 32 μm.

3. The explosion-proof glass back cover according to claim 1, characterized in that: The preparation method of the anti-glare layer is as follows: in a light-proof environment, 20g of nano-silica is gradually added to 80g of UV-curable acrylic resin in five portions at a rate of 4g each, and ultrasonically compounded at 40kHz for 30 minutes to form a uniform slurry; 0.8-1.2g of polyether-modified polysiloxane is slowly added to the premixed slurry under low-speed stirring conditions of 200-500rpm, and stirring is continued for 5-10 minutes until the system is uniform and free of shrinkage cavities; the premixed slurry is injected into the chute of the coating machine, the liquid level is kept constant, and single-sided coating is performed on the surface of the impact-resistant layer to a thickness of 25-35μm; after coating, the substrate is immediately placed in a UV curing box for curing at a light intensity of 1000mJ / cm 2 , the exposure time is 30s, and the anti-glare layer composited to the anti-impact layer is obtained.

4. The explosion-proof glass back cover according to claim 1, characterized in that: The preparation method of the explosion-proof glass body and its nano-toughened laminate is as follows: 0.5mm thick aluminosilicate glass is immersed in 75wt% KNO3 and 25wt% NaNO3 molten salt, and chemically strengthened at 400℃±5℃ for 4 hours to form a strengthening layer; then, a magnetron sputtering process is used on one side of the strengthening layer to form a 5×10 - 6 Under a Torr background vacuum, 10 layers of TiO2 and SiO2 were alternately deposited at 150W RF power and 100W RF power, forming a nano-toughened laminate with a total thickness of 500nm, thus obtaining an explosion-proof glass back cover body with a nano-toughened laminate.

5. The method for preparing an explosion-proof glass back cover according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Preparation of impact-resistant layer: 3-4 g of carboxylated carbon nanotubes were added to 120-150 ml of DMF solvent and pre-dispersed using a high-speed disperser at a speed of 15,000 rpm for 30 min. After pre-dispersion, the mixture was added to 80-100 g of polyurethane prepolymer, and high-speed shearing was performed at 15,000 rpm for 30 min, followed by ultrasonication at 40 kHz for 1 h. The dispersed prepolymer was coated on a PET release film using a precision doctor blade coater at a coating speed of 2 m / min and a gap of 45-55 μm. The film was cured at 100° C. for 30 min and then peeled off to obtain the impact-resistant layer. S2. Preparation of self-healing layer: 45-55 g of dynamic disulfide bond monomer was mixed with 50-70 g of amino silicone oil, and the mixture was reacted at 60° C. under nitrogen protection for 3-5 h. After the reaction, 0.3-0.7 g of platinum catalyst was added and vacuum degassing was carried out in a vacuum planetary mixer at a speed of 2000 rpm and a vacuum degree of -0.1 MPa for 10-20 min. After the reaction, the mixture was cast into a film in a casting machine at a speed of 1 m / min and a film thickness of 28-32 μm. S3. Synthesis of polyether-modified polysiloxane: 2.0-2.4g dimethyl carbonate, 0.22-0.24g high hydrogen silicone oil and 0.04-0.06g hexamethyldisiloxane were added to a reaction kettle by telomerization method, 0.1ml 98% concentrated sulfuric acid was added as catalyst, the reaction was carried out at 60-65℃ for 2-3h, cooled to room temperature, and 3ml The mixture was neutralized with a 10% sodium bicarbonate aqueous solution and filtered; the treated product was then heated to 100-110°C and distilled using a vacuum pump for 1-2 hours to remove low-boiling substances to obtain low-hydrogen silicone oil; 2.1-2.5g of low-hydrogen silicone oil and 1.8-2.1g of allyl polyoxyethylene polyoxypropylene ether were added to a four-necked flask equipped with a stirrer and a thermometer, and nitrogen was introduced and stirred for 5-10 minutes. The mixture was then heated to 80-90°C, 10-20μg / g of chloroplatinic acid catalyst was added, the reaction was carried out for 0.5-1.5 hours, and the temperature was cooled to room temperature to obtain polyether-modified polysiloxane; S4, anti-glare layer compounding: in a light-proof environment, 20g of nano-silicon dioxide was gradually added to 80g of UV curable acrylic resin in five portions at a rate of 4g each, stirring evenly after each addition before adding the next portion. After the addition was complete, ultrasonic compounding was performed at 40kHz for 30min to form a uniform slurry; 0.8-1.2g of the polyether-modified polysiloxane prepared in step S3 was slowly added to the premixed slurry under low-speed stirring conditions of 200-500rpm, and stirring was continued for 5-10 minutes until the system was uniform and free of shrinkage cavities; the premixed slurry was injected into the chute of the coating machine, the liquid level was kept constant, and single-sided coating was performed on the surface of the impact-resistant layer obtained in step S1 with a thickness of 25-35μm; after coating, the substrate was immediately placed in a UV curing box for curing at a light intensity of 1000mJ / cm 2 , the exposure time is 30s, that is, the anti-glare layer is composited onto the impact-resistant layer; S5. Immerse 0.5 mm thick aluminosilicate glass in 75 wt% KNO3 and 25 wt% NaNO3 molten salt and chemically strengthen it at 400℃±5℃ for 4 hours to form a strengthening layer. Then, magnetron sputtering is used on one side of the strengthening layer to form a 5×10 -6 Under a Torr background vacuum, 10 layers of TiO2 and SiO2 were alternately deposited at 150W RF power and 100W RF power, forming a nano-toughened laminate with a total thickness of 500nm, thus obtaining an explosion-proof glass back cover body with a nano-toughened laminate. S6. Soaking the explosion-proof glass back cover body with the nano-toughened laminate prepared in step S5 in an ethanol solution containing 1 wt% KH-550 for 10 minutes, taking it out and rinsing it with deionized water; The anti-glare layer and the impact-resistant layer compounded in step S4, the rinsed explosion-proof glass back cover body with the nano-toughened laminate, and the self-repairing layer prepared in step S2 are laminated in a clean room, with the anti-glare layer facing outward and the self-repairing layer between the impact-resistant layer and the nano-toughened laminate of the explosion-proof glass back cover body; hot pressing and compounding are carried out in a hot press, the heating temperature is set to 90°C, and pre-pressing is performed for 20 to 40 seconds in the initial stage with a pressure of 0.3MPa to eliminate the gap between layers. The subsequent pressure is 0.8MPa full pressure and maintained for 3 minutes. After the end, it is cooled to below 60°C and the mold is opened to obtain an explosion-proof glass back cover with self-repairing anti-glare.

6. The method for preparing an explosion-proof glass back cover according to claim 5, characterized in that: In step S1, the amount of carboxylated carbon nanotubes used is 3.5 g, and the amount of DMF solvent used is 135 ml.

7. The method for preparing an explosion-proof glass back cover according to claim 5, characterized in that: In step S2, 50 g of dynamic disulfide bond monomer and 60 g of amino silicone oil were mixed and reacted at 60° C. for 4 h under nitrogen protection; after the reaction, 0.5 g of platinum catalyst was added.

8. The method for preparing an explosion-proof glass back cover according to claim 5, characterized in that: In step S3, 2.2 g of dimethyl carbonate, 0.23 g of high-hydrogen silicone oil and 0.05 g of hexamethyldisiloxane are taken; during the preparation of polyether-modified polysiloxane, 2.3 g of low-hydrogen silicone oil and 1.91 g of allyl polyoxyethylene polyoxypropylene ether are added in sequence.

9. The method for preparing an explosion-proof glass back cover according to claim 5, characterized in that: In step S4, 20 g of nano-silica was gradually added to 80 g of UV-curable acrylic resin in five portions, and 1.0 g of polyether-modified polysiloxane was added.

10. The method for preparing an explosion-proof glass back cover according to claim 5, characterized in that: The chemical strengthening time in step S5 is 5 hours.

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