Scratch-resistant silica gel film and preparation method thereof

Abstract

The invention relates to the technical field of silica gel membranes, in particular to a scratch-resistant silica gel membrane and a preparation method thereof.The scratch-resistant silica gel membrane is prepared from, by weight, matrix silica gel, core-shell structure composite filler, an elastomer flexibilizer, a composite cross-linking agent, a platinum catalyst, a retarder, an antioxidant and a photoinitiator; through deep integration of component compounding optimization and process innovation, the breakthrough of the comprehensive performance of the scratch-resistant silica gel film is realized, the preparation process is simple, each parameter is easy to control, the core-shell structure composite filler can be self-made through a standardized process, the raw materials are easy to obtain, the production cost is controllable, and the preparation method is suitable for large-scale industrial production. The high-performance requirements of electronics, new energy, precision manufacturing and other high-end fields on the protective film material can be met, and the protective film material has remarkable practical value and market prospect.

Description

Technical Field

[0001] This invention relates to the field of silicone film technology, specifically to a scratch-resistant silicone film and its preparation method. Background Technology

[0002] Silicone films, with their excellent flexibility, resistance to high and low temperatures, and chemical stability, have been widely used in various fields such as electronic device packaging, new energy battery protection, and precision instrument surface protection. As the protection requirements of end products continue to increase, the scratch resistance of silicone films has become one of the key performance indicators. During product handling, assembly, and use, the surface of the film is easily scratched by friction and collision, which not only affects the integrity of the appearance but may also damage the protective function and lead to damage to the substrate.

[0003] To improve scratch resistance, existing technologies typically employ modification methods such as adding inorganic fillers (e.g., silica, alumina) or coating the surface with abrasion-resistant coatings. However, these approaches have significant limitations: inorganic fillers have poor compatibility with the silicone matrix, easily agglomerating and resulting in uneven internal structure of the membrane, which affects both mechanical properties and makes it difficult to achieve stable scratch resistance; surface coating processes increase production steps and costs, and the coating's adhesion to the substrate is insufficient, leading to easy peeling off after long-term use.

[0004] Based on this, the present invention provides a scratch-resistant silicone film to solve the corresponding technical problem. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A scratch-resistant silicone film, made from the following components in parts by weight:

[0007] The matrix consists of 60-80 parts of silicone, 8-15 parts of core-shell composite filler, 3-6 parts of elastomer toughening agent, 4-8 parts of composite crosslinking agent, 0.1-0.3 parts of platinum catalyst, 0.01-0.05 parts of retarder, 0.5-1.5 parts of antioxidant, and 0.05-0.15 parts of photoinitiator.

[0008] As a further technical solution, the matrix silicone is a compound of terminal vinyl silicone oil and polyvinyl silicone oil in a ratio of 3-5:1, wherein the viscosity of the terminal vinyl silicone oil is 50,000-80,000 cps and the vinyl content is 0.3%-0.8%.

[0009] As a further technical solution, the core of the core-shell composite filler is nano-silicon nitride, and the shell is a fluorinated modified organosilicon elastomer graft layer. The fluorinated modified organosilicon elastomer is copolymerized from methyl vinyl siloxane and trifluoropropyl methyl vinyl siloxane, wherein the mass percentage of trifluoropropyl methyl vinyl siloxane is 20%-30%.

[0010] The particle size of the nano-silicon nitride in the core-shell structured composite filler is 25-45 nm, and the number average molecular weight of the fluorine-modified organosilicon elastomer is 5000-15000.

[0011] As a further technical solution, the preparation method of the core-shell composite filler includes the following steps: placing nano-silicon nitride in a 1 mol / L hydrochloric acid solution, activating it at 80-90℃ for 2-3 h, washing it with deionized water until the washing solution is neutral, and drying it at 110-130℃ to constant weight to obtain hydroxylated nano-silicon nitride; placing the hydroxylated nano-silicon nitride in a high-pressure reactor, introducing γ-methacryloyloxypropyltrimethoxysilane vapor, and reacting it at 140-160℃ and 0.3-0.5 MPa for 3-5 h to form a grafting transition layer on the surface of the nano-silicon nitride; adding methyl vinylsiloxane, trifluoropropylmethyl vinylsiloxane and azobisisobutyronitrile initiator to the high-pressure reactor, and polymerizing it in situ at 90-110℃ for 1.5-2.5 h, cooling it to room temperature after the reaction, and then centrifuging and drying it to obtain the core-shell composite filler.

[0012] As a further technical solution, the elastomer toughening agent is a polysiloxane microsphere with a particle size of 50-200 nm.

[0013] As a further technical solution, the composite crosslinking agent is a mixture of hydrogen-terminated silicone oil and amino silicone oil in a ratio of 2-3:1, wherein the hydrogen content of the hydrogen-terminated silicone oil is 0.1%-0.3%.

[0014] As a further technical solution, the platinum catalyst is a chloroplatinic acid-vinylsiloxane complex; the retarder is 1-ethynyl-1-cyclohexanol; the antioxidant is 2,6-di-tert-butyl-4-methylphenol; and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0015] The method for preparing a scratch-resistant silicone film includes the following steps:

[0016] (1) Substrate mixing: Add the matrix silicone, core-shell structure composite filler and elastomer toughening agent to a vacuum kneader and stir for 2-2.5 h at 80-90℃ and -0.08~-0.1MPa. Then add the composite crosslinking agent, platinum catalyst, retarder, antioxidant and photoinitiator in turn, and continue to stir for 1-1.5 h under the above vacuum conditions to obtain the premixed adhesive.

[0017] (2) UV pre-curing: The premixed adhesive is injected into a mold and irradiated with ultraviolet light at an intensity of 50-80 mW / cm. 2 The irradiation time is 30-40 seconds, which forms a preliminary cross-linked structure;

[0018] (3) Gradient curing: For materials that have been pre-cured by ultraviolet light, a temperature gradient curing process is adopted to control the surface temperature of the mold to 120-140℃ and the internal temperature of the mold to 80-100℃, and keep it at the temperature for 2-3 hours to form a gradient cross-linking structure.

[0019] (4) Surface treatment: The membrane material after gradient curing is subjected to plasma treatment with a power of 80-120W and a treatment time of 3-8min to obtain an anti-scratch silicone membrane.

[0020] As a further technical solution, the stirring speed in step (1) is 550 r / min.

[0021] As a further technical solution, the ultraviolet light wavelength in step (2) is 365-405nm.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. In this invention, the matrix silicone oil, a composite of terminal vinyl silicone oil and polyvinyl silicone oil, provides suitable active sites for the crosslinking reaction due to its specific viscosity range and vinyl content, ensuring that the matrix itself has good flexibility and reactivity. This solves the embrittlement problem caused by insufficient or excessive crosslinking density of traditional single matrix silicone oil. The core-shell structured composite filler uses nano-silicon nitride as the core, whose high hardness provides rigid support for the membrane material. The fluorinated modified organosilicon elastomer graft layer effectively avoids the nano-filler from oxidizing due to its chemical compatibility with the matrix silicone oil. The agglomeration of the material reduces the surface energy of the membrane, thereby reducing scratches during friction and solving the problems of poor dispersion and weak bonding between inorganic fillers and the matrix. The elastomer toughening agent, polysiloxane microspheres, fills the voids inside the matrix and undergoes elastic deformation under stress, absorbing impact energy and significantly improving the toughness of the membrane, thus compensating for the brittleness of high-hardness materials. The composite crosslinking agent is a combination of hydrogen-terminated silicone oil and amino silicone oil. The two crosslinking agents work synergistically to form a uniform and stable crosslinking network, solving the problems of low crosslinking efficiency and loose network structure of single crosslinking agents.

[0024] 2. The synergistic effect of each component and process in the technical solution of this invention achieves complementary and optimized performance. The composite system of the matrix silicone provides a good dispersion carrier for the core-shell structure composite filler and elastomer toughening agent, so that the rigid filler and elastic microspheres are evenly distributed in the matrix, forming a rigid support-elastic buffer microstructure, which synergistically improves the scratch resistance and impact resistance of the membrane material. The crosslinking characteristics of the composite crosslinking agent are highly compatible with the gradient curing process. UV pre-curing rapidly forms a preliminary crosslinking structure through short-time high-intensity irradiation, avoiding material flow deformation in subsequent processes. Gradient curing, on the other hand, allows for... By controlling the temperature difference between the mold surface and the interior, the cross-linking reaction proceeds gradually from the outside to the inside, reducing the generation of internal stress and forming a cross-linking network with uniform internal and external properties. At the same time, combined with plasma surface treatment, the surface density of the membrane material is further improved, resulting in a combined improvement in scratch resistance and surface smoothness. The fluorinated shell of the core-shell structure composite filler works synergistically with antioxidants and photoinitiators, which not only reduces the surface friction coefficient of the membrane material, but also enhances the shielding ability against ultraviolet light and oxygen, slows down the aging and degradation rate, and solves the contradiction between scratch resistance and aging resistance of traditional silicone membranes.

[0025] 3. This invention achieves a breakthrough in the comprehensive performance of scratch-resistant silicone film through the deep integration of component compounding optimization and process innovation. The preparation process of this invention is simple, and the parameters are easy to control. The core-shell structure composite filler can be made in-house through a standardized process. The raw materials are readily available, the production cost is controllable, and it is suitable for large-scale industrial production. It can meet the high-performance requirements of protective film materials in high-end fields such as electronics, new energy, and precision manufacturing, and has significant practical value and market prospects. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a scratch-resistant silicone film and its preparation method, which is made of the following components in parts by weight: 60-80 parts of matrix silicone, 8-15 parts of core-shell composite filler, 3-6 parts of elastomer toughening agent, 4-8 parts of composite crosslinking agent, 0.1-0.3 parts of platinum catalyst, 0.01-0.05 parts of retarder, 0.5-1.5 parts of antioxidant, and 0.05-0.15 parts of photoinitiator. The preparation process includes substrate mixing, UV pre-curing, gradient curing, and surface treatment steps, which can significantly improve the scratch resistance, mechanical properties, and stability of the silicone film.

[0028] The raw materials specifically include:

[0029] The matrix silicone is preferably a blend of vinyl-terminated silicone oil and polyvinyl silicone oil in a ratio of 3-5:1. The viscosity of the vinyl-terminated silicone oil is preferably 50,000-80,000 cps, and the vinyl content is preferably 0.3%-0.8%.

[0030] Core-shell structured composite filler: The core is nano-silicon nitride, and the shell is a grafted layer of fluorinated modified organosilicon elastomer. The fluorinated modified organosilicon elastomer is copolymerized from methyl vinylsiloxane and trifluoropropylmethyl vinylsiloxane, wherein the mass percentage of trifluoropropylmethyl vinylsiloxane is preferably 20%-30%. The particle size of the nano-silicon nitride is preferably 25-45 nm, and the number average molecular weight of the fluorinated modified organosilicon elastomer is preferably 5000-15000.

[0031] Elastomer toughening agent: preferably polysiloxane microspheres, with a particle size preferably 50-200 nm.

[0032] Composite crosslinking agent: preferably a mixture of hydrogen-terminated silicone oil and amino silicone oil in a ratio of 2-3:1, wherein the hydrogen content of the hydrogen-terminated silicone oil is preferably 0.1%-0.3%.

[0033] Other additives: platinum catalyst is preferably chloroplatinic acid-vinylsiloxane complex; retardant is preferably 1-ethynyl-1-cyclohexanol; antioxidant is preferably 2,6-di-tert-butyl-4-methylphenol; photoinitiator is preferably 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0034] The core-shell composite filler was prepared as follows:

[0035] Nano-silicon nitride was placed in a 1 mol / L hydrochloric acid solution and activated at 80-90℃ for 2-3 h. After washing with deionized water until the washing solution was neutral, it was dried at 110-130℃ to constant weight to obtain hydroxylated nano-silicon nitride.

[0036] Hydroxylated nano-silicon nitride was placed in a high-pressure reactor and γ-methacryloxypropyltrimethoxysilane vapor was introduced. The reaction was carried out at 140-160℃ and 0.3-0.5MPa for 3-5 hours to form a graft transition layer on the surface of the nano-silicon nitride.

[0037] Methyl vinylsiloxane, trifluoropropylmethyl vinylsiloxane and azobisisobutyronitrile initiator were added to a high-pressure reactor and polymerized in situ at 90-110℃ for 1.5-2.5h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged and dried to obtain a core-shell structured composite filler.

[0038] Preparation methods include:

[0039] Substrate mixing: Add the matrix silicone, core-shell structure composite filler, and elastomer toughening agent to a vacuum kneader and stir at 550 r / min for 2-2.5 h under conditions of 80-90℃ and -0.08~-0.1 MPa. Then add the composite crosslinking agent, platinum catalyst, retarder, antioxidant, and photoinitiator in sequence, and continue stirring under the above vacuum and speed conditions for 1-1.5 h to obtain the premixed adhesive.

[0040] UV pre-curing: The premixed adhesive is injected into the mold and irradiated with UV light with a wavelength of 365-405nm, an irradiation intensity of 50-80mW / cm², and an irradiation time of 30-40s to form a preliminary cross-linked structure.

[0041] Gradient curing: For materials that have been pre-cured by ultraviolet light, a temperature gradient curing process is used to control the surface temperature of the mold to 120-140℃ and the internal temperature of the mold to 80-100℃, and keep it at this temperature for 2-3 hours to form a gradient cross-linked structure.

[0042] Surface treatment: The gradient-cured film material is subjected to plasma treatment with a power of 80-120W and a treatment time of 3-8 minutes to obtain a scratch-resistant silicone film.

[0043] This invention, through specific component combinations and preparation processes, enables scratch-resistant silicone films to possess excellent scratch resistance, tensile strength, and aging resistance, while the preparation process exhibits high stability and is suitable for industrial production.

[0044] To further illustrate the present invention, detailed descriptions are provided below through examples, comparative examples, and experiments. The raw materials used in the following examples and comparative examples of the present invention are as follows:

[0045] Vinyl-terminated silicone oil (viscosity 60000cps, vinyl content 0.5%), polyvinyl silicone oil: commercially available;

[0046] Core-shell structured composite filler: self-made (nano-silicon nitride with a particle size of 35nm, trifluoropropylmethylvinylsiloxane with a mass ratio of 25%, and fluorine-modified organosilicon elastomer with a number average molecular weight of 10,000).

[0047] Polysiloxane microspheres (100nm particle size): Commercially available;

[0048] Hydrogen-containing silicone oil (0.2% hydrogen content), amino silicone oil: commercially available;

[0049] Chloroplatinic acid-vinylsiloxane complex, 1-ethynyl-1-cyclohexanol, 2,6-di-tert-butyl-4-methylphenol, 2-hydroxy-2-methyl-1-phenyl-1-propanone: commercially available.

[0050] Example 1: Preparation of core-shell composite filler: Nano-silicon nitride was placed in a 1 mol / L hydrochloric acid solution and activated at 85°C for 2.5 h. After washing with deionized water until the washing solution was neutral, it was dried at 120°C to constant weight to obtain hydroxylated nano-silicon nitride. The hydroxylated nano-silicon nitride was placed in a high-pressure reactor, and γ-methacryloyloxypropyltrimethoxysilane vapor was introduced. The reaction was carried out at 150°C and 0.4 MPa for 4 h to form a grafted transition layer. Methylvinylsiloxane, trifluoropropylmethylvinylsiloxane and azobisisobutyronitrile initiator were added to the high-pressure reactor, and in-situ polymerization was carried out at 100°C for 2 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged and dried to obtain the core-shell composite filler.

[0051] Substrate Mixing: Weigh out 65 parts by weight of matrix silicone (a 4:1 mixture of terminal vinyl silicone oil and polyvinyl silicone oil), 10 parts by weight of core-shell composite filler, 4 parts by weight of elastomer toughening agent, 5 parts by weight of composite crosslinking agent (a 2.5:1 mixture of terminal hydrogen silicone oil and amino silicone oil), 0.2 parts by weight of platinum catalyst, 0.03 parts by weight of retarder, 1 part by weight of antioxidant, and 0.1 parts by weight of photoinitiator. Add the matrix silicone, core-shell composite filler, and elastomer toughening agent to a vacuum kneader and stir at 550 r / min for 2.2 h at 85℃ and -0.09 MPa. Then add the remaining additives one by one and continue stirring under the above conditions for 1.2 h to obtain a premixed adhesive.

[0052] UV pre-curing: The premixed adhesive is injected into the mold and irradiated with UV light of wavelength 395nm at an intensity of 65mW / cm² for 35s to form a preliminary cross-linked structure.

[0053] Gradient curing: The surface temperature of the mold is controlled at 130℃ and the internal temperature of the mold is 90℃. The temperature is maintained for 2.5 hours to form a gradient cross-linked structure.

[0054] Surface treatment: The membrane material is subjected to plasma treatment with a power of 100W and a treatment time of 5 minutes to obtain a scratch-resistant silicone membrane.

[0055] Example 2: Preparation of core-shell composite filler: Nano-silicon nitride was placed in a 1 mol / L hydrochloric acid solution and activated at 80°C for 2 h. After washing with deionized water until the washing solution was neutral, it was dried at 110°C to constant weight to obtain hydroxylated nano-silicon nitride. The hydroxylated nano-silicon nitride was placed in a high-pressure reactor, and γ-methacryloyloxypropyltrimethoxysilane vapor was introduced. The reaction was carried out at 140°C and 0.3 MPa for 3 h to form a grafted transition layer. Methylvinylsiloxane, trifluoropropylmethylvinylsiloxane and azobisisobutyronitrile initiator were added to the high-pressure reactor, and in-situ polymerization was carried out at 90°C for 1.5 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged and dried to obtain the core-shell composite filler.

[0056] Substrate Mixing: Weigh out 60 parts by weight of matrix silicone (a 3:1 mixture of terminal vinyl silicone oil and polyvinyl silicone oil), 8 parts by weight of core-shell composite filler, 3 parts by weight of elastomer toughening agent, 4 parts by weight of composite crosslinking agent (a 2:1 mixture of terminal hydrogen silicone oil and amino silicone oil), 0.1 parts by weight of platinum catalyst, 0.01 parts by weight of retarder, 0.5 parts by weight of antioxidant, and 0.05 parts by weight of photoinitiator. Add the matrix silicone, core-shell composite filler, and elastomer toughening agent to a vacuum kneader and stir at 550 r / min for 2 h at 80℃ and -0.08 MPa. Then add the remaining additives one at a time and continue stirring for 1 h under the above conditions to obtain a premixed adhesive.

[0057] UV pre-curing: The premixed adhesive is injected into the mold and irradiated with UV light of wavelength 365nm at an intensity of 50mW / cm² for 30s to form a preliminary cross-linked structure.

[0058] Gradient curing: The surface temperature of the mold is controlled at 120℃ and the internal temperature of the mold is 80℃. The temperature is maintained for 2 hours to form a gradient cross-linked structure.

[0059] Surface treatment: The membrane material is subjected to plasma treatment with a power of 80W and a treatment time of 3 minutes to obtain a scratch-resistant silicone membrane.

[0060] Example 3: Preparation of core-shell composite filler: Nano-silicon nitride was placed in a 1 mol / L hydrochloric acid solution and activated at 90°C for 3 h. After washing with deionized water until the washing solution was neutral, it was dried at 130°C to constant weight to obtain hydroxylated nano-silicon nitride. The hydroxylated nano-silicon nitride was placed in a high-pressure reactor, and γ-methacryloyloxypropyltrimethoxysilane vapor was introduced. The reaction was carried out at 160°C and 0.5 MPa for 5 h to form a grafted transition layer. Methylvinylsiloxane, trifluoropropylmethylvinylsiloxane and azobisisobutyronitrile initiator were added to the high-pressure reactor, and in-situ polymerization was carried out at 110°C for 2.5 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged and dried to obtain the core-shell composite filler.

[0061] Substrate Mixing: Weigh out 80 parts by weight of matrix silicone (a 5:1 mixture of terminal vinyl silicone oil and polyvinyl silicone oil), 15 parts by weight of core-shell composite filler, 6 parts by weight of elastomer toughening agent, 8 parts by weight of composite crosslinking agent (a 3:1 mixture of terminal hydrogen silicone oil and amino silicone oil), 0.3 parts by weight of platinum catalyst, 0.05 parts by weight of retarder, 1.5 parts by weight of antioxidant, and 0.15 parts by weight of photoinitiator. Add the matrix silicone, core-shell composite filler, and elastomer toughening agent to a vacuum kneader and stir at 550 r / min for 2.5 h at 90 °C and -0.1 MPa. Then add the remaining additives one at a time and continue stirring under the above conditions for 1.5 h to obtain a premixed adhesive.

[0062] UV pre-curing: The premixed adhesive is injected into the mold and irradiated with UV light at a wavelength of 405nm, with an irradiation intensity of 80mW / cm² and an irradiation time of 40s, to form a preliminary cross-linked structure.

[0063] Gradient curing: The surface temperature of the mold is controlled at 140℃ and the internal temperature of the mold is 100℃. The temperature is maintained for 3 hours to form a gradient cross-linked structure.

[0064] Surface treatment: The membrane material is subjected to plasma treatment with a power of 120W and a treatment time of 8 minutes to obtain a scratch-resistant silicone membrane.

[0065] Comparative Example 1: The preparation method of Example 1 was used, except that the raw materials did not contain core-shell structured composite fillers, and the remaining components and their weight parts were 75 parts of matrix silicone, 4 parts of elastomer toughening agent, 5 parts of composite crosslinking agent, 0.2 parts of platinum catalyst, 0.03 parts of retarder, 1 part of antioxidant, and 0.1 parts of photoinitiator.

[0066] Comparative Example 2: The preparation method of Example 1 was used, except that the raw materials did not contain elastomer toughening agents, and the remaining components and their weight parts were 69 parts of matrix silicone, 10 parts of core-shell structure composite filler, 5 parts of composite crosslinking agent, 0.2 parts of platinum catalyst, 0.03 parts of retarder, 1 part of antioxidant, and 0.1 parts of photoinitiator.

[0067] Comparative Example 3: The preparation method of Example 1 was used, except that the composite crosslinking agent was replaced with 5 parts of end-hydrogen-containing silicone oil (excluding amino silicone oil), while the other components and their weight parts remained unchanged.

[0068] Comparative Example 4: The preparation method of Example 1 was used, except that step 3 was changed to constant temperature curing, the mold temperature was controlled at 110℃ and kept at that temperature for 2.5h, and the other steps remained unchanged.

[0069] test:

[0070] Experiment 1: Scratch resistance test;

[0071] Referring to GB / T6739-2021, a 2H pencil was used to scratch the surface of the silicone film at a uniform speed and angle of 45° under a load of 500g, and the surface scratches were observed. Simultaneously, referring to GB / T1732-2021, a 1kg hammer was dropped from a height of 50cm onto the film material, and the surface damage was observed. The results are as follows:

[0072] Table 1

[0073] sample Pencil scratch rating Surface condition after impact Example 1 2H scratch-free No damage, no cracks Example 2 2H Minor Scratches No damage, slightly white Example 3 2H scratch-free No damage, no cracks Comparative Example 1 HB obvious scratches Localized damage, cracks appear Comparative Example 2 Slight scratches Localized damage, no cracks Comparative Example 3 H obvious scratches Localized damage, minor cracks Comparative Example 4 Slight scratches No damage, visibly white

[0074] As shown in Table 1, the scratch resistance of Examples 1-3 is significantly better than that of the comparative examples. The reasons are as follows: Comparative Example 1 lacks a core-shell composite filler, and the rigid core of nano-silicon nitride and the fluorinated elastomer shell cannot synergistically improve surface hardness and scratch resistance, resulting in a lower pencil scratch rating and easy breakage after impact. Comparative Example 2 lacks an elastomer toughening agent, resulting in insufficient toughness of the membrane material, making it prone to local breakage after impact, and also slightly reducing surface hardness. Comparative Example 3 uses a single-end hydrogen-containing silicone oil as a crosslinking agent, which cannot form a uniform crosslinking network, resulting in insufficient surface density of the membrane material and reduced scratch resistance. Comparative Example 4 uses isothermal curing, which cannot form a gradient crosslinking structure, resulting in uneven internal and external properties of the membrane material and weakened surface scratch resistance and impact resistance.

[0075] Experiment 2: Tensile property test;

[0076] According to GB / T1040.3-2006, dumbbell-shaped specimens were prepared, and the tensile speed was 50 mm / min. The tensile strength and elongation at break were tested, and the results are as follows:

[0077] Table 2

[0078] sample Tensile strength (MPa) Elongation at break (%) Example 1 8.5 380 Example 2 7.2 320 Example 3 9.1 410 Comparative Example 1 5.3 250 Comparative Example 2 6.8 280 Comparative Example 3 6.5 300 Comparative Example 4 7.0 310

[0079] As shown in Table 2, the tensile properties of Examples 1-3 are significantly better than those of the comparative examples. The reasons are as follows: Comparative Example 1 lacks a core-shell composite filler, thus failing to enhance mechanical properties through the interfacial interaction between the filler and the matrix, resulting in a significant decrease in tensile strength and elongation at break. Comparative Example 2 lacks an elastomer toughening agent, leading to insufficient toughness of the membrane material, reduced elongation at break, and a slight decrease in tensile strength. The single crosslinking agent in Comparative Example 3 cannot form a stable crosslinking network, resulting in a loose internal structure of the membrane material, and both tensile strength and elongation at break are lower than those of the examples. The isothermal curing in Comparative Example 4 leads to uneven crosslinking of the membrane material, internal stress concentration, and slightly inferior tensile properties compared to the examples.

[0080] Experiment 3: Aging resistance test;

[0081] According to GB / T16422.2-2014, the samples were placed in a xenon arc lamp aging test chamber with an irradiation intensity of 0.5 W / m² (340 nm), a temperature of 65℃, and a relative humidity of 50%. After aging for 1000 hours, the tensile strength retention rate and yellowing index were tested, and the results are as follows:

[0082] Table 3

[0083] sample Tensile strength retention rate (%) Yellowing index (ΔYI) Example 1 92 1.8 Example 2 88 2.3 Example 3 94 1.5 Comparative Example 1 75 3.5 Comparative Example 2 82 2.8 Comparative Example 3 80 3.2 Comparative Example 4 83 2.9

[0084] As shown in Table 3, the aging resistance of Examples 1-3 is superior to that of the comparative examples. The specific reasons are as follows: Comparative Example 1 lacks a core-shell composite filler, resulting in the loss of the UV resistance and antioxidant effect of the fluorinated modified layer. Simultaneously, the shielding effect of nano-silicon nitride is lost, leading to a decrease in tensile strength retention and an increase in the yellowing index. Comparative Example 2 lacks an elastomer toughening agent, making the membrane prone to cracking during aging, accelerating aging degradation, and reducing tensile strength retention. The crosslinking network formed by the single crosslinking agent in Comparative Example 3 has insufficient stability, and the crosslinking bonds are easily broken after aging, resulting in decreased aging resistance. The isothermal curing in Comparative Example 4 introduces defects into the internal structure of the membrane, making these defects prone to degradation during aging, resulting in slightly worse aging resistance than the examples.

[0085] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A scratch-resistant silicone film, characterized in that, It is made from the following components in parts by weight: The matrix consists of 60-80 parts of silicone, 8-15 parts of core-shell composite filler, 3-6 parts of elastomer toughening agent, 4-8 parts of composite crosslinking agent, 0.1-0.3 parts of platinum catalyst, 0.01-0.05 parts of retarder, 0.5-1.5 parts of antioxidant, and 0.05-0.15 parts of photoinitiator.

2. The scratch-resistant silicone film according to claim 1, characterized in that, The matrix silicone is a compound of vinyl-terminated silicone oil and polyvinyl silicone oil in a ratio of 3-5:

1. The viscosity of the vinyl-terminated silicone oil is 50,000-80,000 cps, and the vinyl content is 0.3%-0.8%.

3. The scratch-resistant silicone film according to claim 1, characterized in that, The core of the core-shell composite filler is nano-silicon nitride, and the shell is a fluorinated modified organosilicon elastomer graft layer. The fluorinated modified organosilicon elastomer is copolymerized from methyl vinyl siloxane and trifluoropropyl methyl vinyl siloxane, wherein the mass percentage of trifluoropropyl methyl vinyl siloxane is 20%-30%. The particle size of the nano-silicon nitride in the core-shell structured composite filler is 25-45 nm, and the number average molecular weight of the fluorine-modified organosilicon elastomer is 5000-15000.

4. The scratch-resistant silicone film according to claim 3, characterized in that, The preparation method of the core-shell composite filler includes the following steps: placing nano-silicon nitride in a 1 mol / L hydrochloric acid solution, activating it at 80-90℃ for 2-3 h, washing it with deionized water until the washing solution is neutral, and drying it at 110-130℃ to constant weight to obtain hydroxylated nano-silicon nitride; placing the hydroxylated nano-silicon nitride in a high-pressure reactor, introducing γ-methacryloyloxypropyltrimethoxysilane vapor, and reacting it at 140-160℃ and 0.3-0.5 MPa for 3-5 h to form a graft transition layer on the surface of the nano-silicon nitride; adding methyl vinylsiloxane, trifluoropropylmethyl vinylsiloxane and azobisisobutyronitrile initiator to the high-pressure reactor, and polymerizing it in situ at 90-110℃ for 1.5-2.5 h; after the reaction is completed, cooling it to room temperature, centrifuging and drying it to obtain the core-shell composite filler.

5. The scratch-resistant silicone film according to claim 1, characterized in that, The elastomer toughening agent is a polysiloxane microsphere with a particle size of 50-200 nm.

6. The scratch-resistant silicone film according to claim 1, characterized in that, The composite crosslinking agent is a mixture of hydrogen-terminated silicone oil and amino silicone oil in a ratio of 2-3:1, and the hydrogen content of the hydrogen-terminated silicone oil is 0.1%-0.3%.

7. The scratch-resistant silicone film according to claim 1, characterized in that, The platinum catalyst is a chloroplatinic acid-vinylsiloxane complex; the retarder is 1-ethynyl-1-cyclohexanol; the antioxidant is 2,6-di-tert-butyl-4-methylphenol; and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

8. A method for preparing an anti-scratch silicone film as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Substrate mixing: Add the matrix silicone, core-shell structure composite filler and elastomer toughening agent to a vacuum kneader and stir for 2-2.5 h at 80-90℃ and -0.08~-0.1MPa. Then add the composite crosslinking agent, platinum catalyst, retarder, antioxidant and photoinitiator in turn, and continue to stir for 1-1.5 h under the above vacuum conditions to obtain the premixed adhesive. (2) UV pre-curing: The premixed adhesive is injected into a mold and irradiated with ultraviolet light at an intensity of 50-80 mW / cm. 2 The irradiation time is 30-40 seconds, which forms a preliminary cross-linked structure; (3) Gradient curing: For materials that have been pre-cured by ultraviolet light, a temperature gradient curing process is adopted to control the surface temperature of the mold to 120-140℃ and the internal temperature of the mold to 80-100℃, and keep it at the temperature for 2-3 hours to form a gradient cross-linking structure. (4) Surface treatment: The membrane material after gradient curing is subjected to plasma treatment with a power of 80-120W and a treatment time of 3-8min to obtain an anti-scratch silicone membrane.

9. The preparation method according to claim 8, characterized in that, The stirring speed in step (1) is 550 r / min.

10. The preparation method according to claim 8, characterized in that, In step (2), the ultraviolet light wavelength is 365-405nm.