Flame-retardant silicone rubber composite material and preparation method thereof

Abstract

The invention relates to the technical field of silicone rubber composite materials, in particular to a flame-retardant silicone rubber composite material and a preparation method thereof, and the flame-retardant silicone rubber composite material comprises a matrix polymer, a reinforcing filler, a compound flame-retardant system, a reinforced protection system, a crosslinking system and a processing aid. According to the material disclosed by the invention, synchronous breakthrough is realized on three core indexes of flame retardance, mechanical strength and durability, and the technical defects of a traditional silicon rubber material are overcome; the problems of non-uniform dispersion of a high-filling system, catalyst deactivation, interface layering and the like are fundamentally solved, the method is particularly suitable for the fields of power battery sealing, aerospace cables and the like which require an extreme flame retardant grade and need to maintain a flexible sealing function, and a scheme capable of realizing mass production is provided for a high-performance organic silicon material.

Description

Technical Field

[0001] The present invention relates to the technical field of silicone rubber composite materials, in particular to a flame retardant silicone rubber composite material and a preparation method thereof. Background Art

[0002] Silicone rubber composite materials mainly rely on methyl vinyl silicone rubber as the matrix, with high additions of inorganic flame retardants such as aluminum hydroxide and unmodified fumed silica reinforcing fillers.

[0003] However, in general, such materials require the addition of a large amount of flame retardants to barely reach the V-1 flame retardancy rating, but excessive fillers will seriously damage the continuity of the molecular chain, resulting in a sharp drop in mechanical strength and loss of elasticity. At the same time, the aluminum hydroxide in the traditional system is easy to agglomerate during high-temperature vulcanization due to its surface hydrophilicity, forming local flame retardant weak areas; direct exposure of phosphorus-based flame retardants will cause irreversible poisoning with the platinum catalyst, resulting in incomplete vulcanization, and its curing process relies on the thermal decomposition of a single peroxide, resulting in insufficient interfacial bonding strength. After long-term use, it is prone to droplets and powdering failure, especially in harsh environments such as electrolytes.

[0004] Based on this, the present invention provides a flame retardant silicone rubber composite material and a preparation method thereof to solve the above-mentioned technical problems. Summary of the Invention

[0005] The object of the present invention is to provide a flame retardant silicone rubber composite material and a preparation method thereof, so as to solve the problems mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a flame-retardant silicone rubber composite material, including a matrix polymer, a reinforcing filler, a compounded flame retardant system, an enhanced protection system, a cross-linking system, and a processing aid:

[0008] The matrix polymer is composed of the following raw materials in parts by weight: vinyl-terminated polydimethylsiloxane: 100 parts;

[0009] The reinforcing filler is composed of the following raw materials in parts by weight: fumed silica: 15-25 parts;

[0010] The composite flame retardant system is composed of the following raw materials in parts by weight:

[0011] Aluminum hydroxide: 30-45 parts;

[0012] Magnesium hydroxide: 15-25 parts;

[0013] The ratio of magnesium hydroxide to aluminum hydroxide is 1:(1.5-2.0);

[0014] Sodium tetraborate decahydrate: 5-10 parts;

[0015] Tris(β-chloroethyl) phosphate: 3-8 parts;

[0016] The enhanced protection system is composed of the following raw materials in parts by weight:

[0017] End-hydrogenated polymethylsiloxane: 2-5 parts;

[0018] Vinyltrimethoxysilane: 1-3 parts;

[0019] The cross-linking system is composed of the following raw materials in parts by weight:

[0020] 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane: 0.5-1.5 parts;

[0021] Platinum complex catalyst: 0.01-0.05 parts;

[0022] The processing aid is composed of the following raw materials in parts by weight:

[0023] Structure control agent: 1-3 parts;

[0024] The structure control agent is one of diphenylsilanediol or hexamethyldisilazane;

[0025] Heat-resistant additives: 1-3 parts.

[0026] Preferably, the tris(β-chloroethyl) phosphate is prepared by dispersing ammonium polyphosphate with a degree of polymerization greater than 1000 in an aqueous solution containing 1-3 wt% of an alkylnaphthalene sulfonate formaldehyde condensate, adding dropwise a wall material solution consisting of a melamine-formaldehyde prepolymer and 5-8 wt% of carboxymethyl cellulose at 40-60° C. and a shear rate of 3000-5000 rpm, and subjecting the mixture to in-situ polymerization in an acidic environment of pH 3.5-4.0 for 2-4 hours. The microcapsule has an encapsulation efficiency of ≥92% and a purity of ≥99.0%.

[0027] Preferably, the sodium tetraborate decahydrate is prepared by placing industrial sodium tetraborate decahydrate in a plasma enhanced chemical vapor deposition furnace, introducing hexamethyldisiloxane vapor under a vacuum of 0.1-1.0 kPa and an environment of 300-400° C. for surface hydrophobic deposition for 20-30 minutes, and the product has a contact angle of >120° and a purity of ≥98.5%.

[0028] Preferably, the platinum complex catalyst is prepared by chelating chloroplatinic acid with a vinyl-containing cage-type silsesquioxane in a toluene solution at 80-100° C. for 6-8 hours under nitrogen protection, followed by molecular distillation to remove the solvent and small molecular by-products. The platinum content is 3.0-3.5wt%, the catalyst activity half-life is extended by 3 times, and the purity is ≥99.9%.

[0029] Preferably, the fumed silica is prepared by subjecting untreated fumed silica to a gas phase surface grafting by atomizing and spraying a mixture of hexamethyldisilazane and dimethyldiethoxysilane in a mass ratio of 1:2 in a fluidized bed reactor at 200-250°C and a negative pressure of -0.08 to -0.05 MPa, with a grafting density of 1.8-2.2 cells / nm. 2 , purity ≥99.8%.

[0030] Preferably, the heat-resistant additive is prepared by dissolving ammonium cerium nitrate in a mixture of ethylene glycol and citric acid at a molar ratio of 1:1.5, pressurizing to 1.5-2.0 MPa in a hydrothermal reactor at 160-180° C. for 12-16 hours to generate monodisperse cubic cerium oxide nanoparticles with an average particle size of 15±3 nm and a purity of ≥99.95%.

[0031] Preferably, the hydrogen-terminated polymethylsiloxane is prepared by anionic ring-opening polymerization of octamethylcyclotetrasiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane under a dynamic vacuum of <100 Pa and 80° C., using tetramethylammonium hydroxide as a catalyst, and precisely controlling the feeding sequence of the chain terminator tetramethyldihydrogendisiloxane. The hydrogen content is 0.18-0.22wt%, the molecular weight distribution index is ≤1.15, and the purity is ≥99.5%.

[0032] Preferably, the silane coupling agent is prepared by exposing vinyltrimethoxysilane and 20-30 nm nano-titanium dioxide aerosol to a dielectric barrier discharge plasma for 15-20 minutes under ultrasonic radiation and argon atmosphere to achieve directional activation of silane molecules, with a hydrolysis rate increased by 5 times and a purity of ≥99.0%.

[0033] The present invention also provides a method for preparing a flame retardant silicone rubber composite material, comprising the following steps:

[0034] S1: Flame retardant filler plasma activation pretreatment:

[0035] Aluminum hydroxide (30-45 parts) and magnesium hydroxide (15-25 parts) are added to the twin-screw feeding bin in proportion; radio frequency plasma is activated in the second section of the screw barrel, and sodium tetraborate decahydrate (5-10 parts) and vinyltrimethoxysilane (1-3 parts) are sprayed in by atomization; surface chemical grafting is completed under a vacuum environment, and the outlet material is tested by a laser particle size analyzer.

[0036] S2: High shear dispersion of matrix composite slurry:

[0037] Vinyl-terminated polydimethylsiloxane (100 parts), hydrogen-terminated polymethylsiloxane (2-5 parts), and a structure control agent (1-3 parts) are pumped into a central distributor of a reactor; the liquid phase is flung toward the packing layer using a centrifugal force of 2000 g, and fumed silica (15-25 parts) and the activated flame-retardant filler obtained in step S1 are simultaneously injected; nanodispersion is completed under high-speed rotation, and the Stormer viscosity of the slurry is measured;

[0038] S3: Microfluidic dispersion of nano-functional additives:

[0039] The slurry obtained in step S2 is premixed with tris(β-chloroethyl) phosphate (3-8 parts) and a heat-resistant additive (1-3 parts) and then pumped into a storage tank; large particle agglomerates are crushed under a first-stage pressure of 120 MPa; nanoparticles are allowed to penetrate the gaps between siloxane molecular chains under an ultrahigh pressure of 180 MPa, and the zeta potential of the slurry is detected online;

[0040] S4: Two-component isolation packaging:

[0041] 70% of the total slurry was transferred to the component A tank, and a platinum catalyst (0.01-0.05 parts) was added and homogenized in a static mixer. The mixing temperature of component A was 20±1°C. The remaining 30% of the slurry was transferred to the component B tank and mixed with 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane (0.5-1.5 parts). The mixing temperature of component B was 22±1°C. The slurry was then dispensed simultaneously using a dual-channel filling head in an environment with an oxygen content of <1ppm. The mass ratio error of components A and B was ≤0.3%.

[0042] S5: Field-assisted step curing:

[0043] The AB components are extruded and coated on the sealing surface in a 1:1 ratio and placed in an alternating magnetic field to arrange the fillers in an orderly manner along the stress direction; medium-wave infrared is activated to melt the matrix and penetrate the interface; under short-wave infrared, the synergistic reaction of platinum-catalyzed hydrosilylation and peroxide cross-linking is triggered to detect the curing depth.

[0044] Preferably, in step S5, the alternating magnetic field strength is 15 kA / m to induce directional alignment for 10 minutes; the medium-wave infrared power density is 4 W / cm 2 , gradient heating to 100℃; short-wave infrared power density 8W / cm 2 Fast curing up to 160°C.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The material of the present invention achieves simultaneous breakthroughs in the three core indicators of flame retardancy, mechanical strength and durability, solving the technical defects of traditional silicone rubber materials. Through plasma-activated fillers, microencapsulation of functional components and field-assisted directional solidification technology, it fundamentally solves the problems of uneven dispersion of high-filling systems, catalyst deactivation and interface stratification. It is particularly suitable for fields such as power battery sealing and aerospace cables that require extreme flame retardancy while maintaining flexible sealing functions, providing a mass-producible solution for high-performance silicone materials. DETAILED DESCRIPTION

[0047] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] 1. Materials:

[0049] The flame retardant silicone rubber composite material of the present invention, raw materials not specified, are all commercially available;

[0050] Including base polymer, reinforcing filler, compound flame retardant system, enhanced protection system, cross-linking system and processing aids:

[0051] The matrix polymer is composed of the following raw materials in parts by weight: vinyl-terminated polydimethylsiloxane: 100 parts;

[0052] The reinforcing filler is composed of the following raw materials in parts by weight: fumed silica: 15-25 parts;

[0053] The compound flame retardant system is composed of the following raw materials in parts by weight:

[0054] Aluminum hydroxide: 30-45 parts;

[0055] Magnesium hydroxide: 15-25 parts;

[0056] The ratio of magnesium hydroxide to aluminum hydroxide is 1:(1.5-2.0);

[0057] Sodium tetraborate decahydrate: 5-10 parts;

[0058] Tris(β-chloroethyl) phosphate: 3-8 parts;

[0059] The enhanced protection system is composed of the following raw materials in parts by weight:

[0060] End-hydrogenated polymethylsiloxane: 2-5 parts;

[0061] Vinyltrimethoxysilane: 1-3 parts;

[0062] The cross-linking system is composed of the following raw materials in parts by weight:

[0063] 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane: 0.5-1.5 parts;

[0064] Platinum complex catalyst: 0.01-0.05 parts;

[0065] The processing aid is composed of the following raw materials in parts by weight:

[0066] Structure control agent: 1-3 parts;

[0067] The structure control agent is one of diphenylsilanediol or hexamethyldisilazane;

[0068] Heat-resistant additives: 1-3 parts.

[0069] It should also be noted that tris(β-chloroethyl) phosphate is prepared by dispersing ammonium polyphosphate with a degree of polymerization >1000 in an aqueous solution containing 1-3 wt% of an alkylnaphthalene sulfonate formaldehyde condensate. A wall material solution consisting of a melamine-formaldehyde prepolymer and 5-8 wt% of carboxymethyl cellulose is added dropwise at 40-60°C and a shear rate of 3000-5000 rpm. The mixture is in situ polymerized in an acidic environment of pH 3.5-4.0 for 2-4 hours to obtain a microcapsule with an encapsulation efficiency of ≥92% and a purity of ≥99.0%.

[0070] It should also be noted that sodium tetraborate decahydrate is prepared by placing industrial sodium tetraborate decahydrate in a plasma-enhanced chemical vapor deposition furnace, introducing hexamethyldisiloxane vapor for surface hydrophobic deposition for 20-30 minutes under a vacuum of 0.1-1.0 kPa and an environment of 300-400°C. The product has a contact angle of >120° and a purity of ≥98.5%.

[0071] It should also be noted that the platinum complex catalyst is prepared by chelating chloroplatinic acid with a vinyl-containing cage-type silsesquioxane in a toluene solution at 80-100°C under nitrogen protection for 6-8 hours, followed by molecular distillation to remove the solvent and small molecular by-products. The platinum content is 3.0-3.5wt%, the catalyst activity half-life is extended by 3 times, and the purity is ≥99.9%.

[0072] Among them, it should be noted that fumed silica is prepared by grafting the untreated fumed silica on the surface of the untreated fumed silica in a fluidized bed reactor at 200-250°C and a negative pressure of -0.08 to -0.05 MPa by spraying a mixture of hexamethyldisilazane and dimethyldiethoxysilane in a mass ratio of 1:2, with a grafting density of 1.8-2.2 cells / nm 2 , purity ≥99.8%.

[0073] It should also be noted that the heat-resistant additive is prepared by dissolving ammonium cerium nitrate in a mixture of ethylene glycol and citric acid in a molar ratio of 1:1.5, pressurizing it to 1.5-2.0 MPa in a hydrothermal reactor at 160-180°C for 12-16 hours to generate monodisperse cubic cerium oxide nanoparticles with an average particle size of 15±3 nm and a purity of ≥99.95%.

[0074] It should also be noted that the hydrogen-terminated polymethylsiloxane is prepared by anionic ring-opening polymerization of octamethylcyclotetrasiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane under a dynamic vacuum of <100 Pa and 80°C, using tetramethylammonium hydroxide as a catalyst and precisely controlling the feeding sequence of the chain terminator tetramethyldihydrogendisiloxane. The hydrogen content is 0.18-0.22wt%, the molecular weight distribution index is ≤1.15, and the purity is ≥99.5%.

[0075] It should also be noted that the silane coupling agent is prepared by exposing vinyltrimethoxysilane and 20-30 nm nano-titanium dioxide aerosol to a dielectric barrier discharge plasma under ultrasonic radiation and an argon atmosphere for 15-20 minutes to achieve directional activation of the silane molecules. The hydrolysis rate is increased by 5 times and the purity is ≥99.0%.

[0076] 2. Process:

[0077] A method for preparing a flame-retardant silicone rubber composite material based on the above-mentioned material comprises the following steps:

[0078] S1: Flame retardant filler plasma activation pretreatment:

[0079] Aluminum hydroxide (30-45 parts) and magnesium hydroxide (15-25 parts) are added to the twin-screw feeding bin in proportion; radio frequency plasma is activated in the second section of the screw barrel, and sodium tetraborate decahydrate (5-10 parts) and vinyltrimethoxysilane (1-3 parts) are sprayed in by atomization; surface chemical grafting is completed under a vacuum environment, and the outlet material is tested by a laser particle size analyzer.

[0080] S2: High shear dispersion of matrix composite slurry:

[0081] Vinyl-terminated polydimethylsiloxane (100 parts), hydrogen-terminated polymethylsiloxane (2-5 parts), and a structure control agent (1-3 parts) are pumped into a central distributor of a reactor; the liquid phase is flung toward the packing layer using a centrifugal force of 2000 g, and fumed silica (15-25 parts) and the activated flame-retardant filler obtained in step S1 are simultaneously injected; nanodispersion is completed under high-speed rotation, and the Stormer viscosity of the slurry is measured;

[0082] S3: Microfluidic dispersion of nano-functional additives:

[0083] The slurry obtained in step S2 is premixed with tris(β-chloroethyl) phosphate (3-8 parts) and a heat-resistant additive (1-3 parts) and then pumped into a storage tank; large particle agglomerates are crushed under a first-stage pressure of 120 MPa; nanoparticles are allowed to penetrate the gaps between siloxane molecular chains under an ultrahigh pressure of 180 MPa, and the zeta potential of the slurry is detected online;

[0084] S4: Two-component isolation packaging:

[0085] 70% of the total slurry was transferred to the component A tank, and a platinum catalyst (0.01-0.05 parts) was added and homogenized in a static mixer. The mixing temperature of component A was 20±1°C. The remaining 30% of the slurry was transferred to the component B tank and mixed with 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane (0.5-1.5 parts). The mixing temperature of component B was 22±1°C. The slurry was then dispensed simultaneously using a dual-channel filling head in an environment with an oxygen content of <1ppm. The mass ratio error of components A and B was ≤0.3%.

[0086] S5: Field-assisted step curing:

[0087] The AB components are extruded and coated on the sealing surface in a 1:1 ratio and placed in an alternating magnetic field to arrange the fillers in an orderly manner along the stress direction; medium-wave infrared is activated to melt the matrix and penetrate the interface; under short-wave infrared, the synergistic reaction of platinum-catalyzed hydrosilylation and peroxide cross-linking is triggered to detect the curing depth.

[0088] It should be noted that in step S5, the alternating magnetic field strength is 15 kA / m to induce directional alignment for 10 minutes; the medium-wave infrared power density is 4 W / cm 2 , gradient heating to 100℃; short-wave infrared power density 8W / cm 2 Fast curing up to 160°C.

[0089] Example 1: In this example, a flame-retardant silicone rubber composite material includes the following components: vinyl-terminated polydimethylsiloxane: 100; fumed silica: 20; aluminum hydroxide: 37.5; magnesium hydroxide: 20 (ratio 1:1.875); sodium tetraborate decahydrate: 7.5; tris(β-chloroethyl) phosphate: 5.5; hydrogen-terminated polymethylsiloxane: 3.5; vinyltrimethoxysilane: 2; 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane: 1.0; platinum complex catalyst: 0.03; structure control agent (diphenylsilanediol): 2; heat-resistant additive (cerium oxide): 2;

[0090] The flame retardant silicone rubber composite material was prepared according to the following process steps:

[0091] Plasma treatment time in S1: 30 minutes;

[0092] Centrifugal force in S2: 2000 g (corresponding to a speed of 3250 rpm);

[0093] The parameters of each stage in S5 are the above standard values;

[0094] Example 2: The difference from Example 1: the aluminum hydroxide is 30 parts, the magnesium hydroxide is 20 parts (ratio 1:1.5), the other components are the same as Example 1, and the process parameters are the same as Example 1.

[0095] Example 3: The difference from Example 1: aluminum hydroxide is 40 parts, magnesium hydroxide is 20 parts (ratio 1:2.0), other components are the same as Example 1, and the process parameters are the same as Example 1.

[0096] Example 4: The difference from Example 1: tri(β-chloroethyl) phosphate is 3 parts, sodium tetraborate decahydrate is 10 parts, other components are the same as in Example 1, and the process parameters are the same as in Example 1.

[0097] Example 5: Difference from Example 1: The process parameter is changed to plasma treatment time of 28 minutes, and the rest is the same as Example 1.

[0098] The components of the embodiment are shown in Table 1:

[0099] Table 1 Composition and process parameters of flame retardant silicone rubber composite materials in the embodiment

[0100]

[0101]

[0102] Comparative Example 1: Difference from Example 1: 25 parts of aluminum hydroxide, 30 parts of magnesium hydroxide, ratio 1:1.2, other components are the same as Example 1, and the process parameters are the same as Example 1.

[0103] Comparative Example 2: Difference from Example 1: Tris(β-chloroethyl) phosphate is 2 parts, other components are the same as in Example 1, and the process parameters are the same as in Example 1.

[0104] Comparative Example 3: The difference from Example 1 is that the amount of tri(β-chloroethyl) phosphate is 10 parts, the other components are the same as in Example 1, and the process parameters are the same as in Example 1.

[0105] Comparative Example 4: Difference from Example 1: The amount of sodium tetraborate decahydrate is 3 parts, the other components are the same as in Example 1, and the process parameters are the same as in Example 1.

[0106] Comparative Example 5: Difference from Example 1: The process parameters are changed to plasma treatment time of 20 minutes, and the other parameters are the same as Example 1;

[0107] The components of the comparative example are shown in Table 2:

[0108] Table 2 Components and process parameters of flame retardant silicone rubber composite materials in comparative examples

[0109]

[0110]

[0111] 3. Performance testing:

[0112] Silicone rubber composite material samples were prepared according to the components and process parameters of the embodiment and comparative example, and the performance of the samples prepared in the embodiment and comparative example was tested according to the test standards:

[0113] The test data of each sample in Example 1 to Example 5 are shown in Table 3:

[0114] Table 3: Detection data of samples in Examples 1 to 5

[0115]

[0116] The test data of each sample in Comparative Examples 1 to 5 are shown in Table 4:

[0117] Table 4 Test data of samples in Comparative Examples 1-5

[0118]

[0119]

[0120] 4. Analysis Conclusions:

[0121] According to Tables 1 to 4, when Mg:Al=1:1.5-2.0, LOI ≥36.8% in Examples 1-3 is better than Comparative Example 1. Due to the imbalance in the ratio, the overlap of the endothermic peaks decreases. In Examples 1, 4, and 5, 3-8 parts of phosphate triester combined with 5-10 parts of sodium tetraborate decahydrate can achieve zero droplet. When the sodium tetraborate decahydrate in Comparative Example 3 is less than 5 parts, droplet occurs. Therefore, the scientificity of the component intervals of the embodiments of the present invention can be seen. In Examples 1, 4, and 5, 15-25 parts of fumed silica combined with 1-3 parts of vinyltrimethoxysilane make the tear strength ≥15.6 kN / m. When the fumed silica in Example 4 is insufficient, the tear strength decreases by 19%.

[0122] Furthermore, because the components and process parameters of the embodiment of the present invention reach Mg:Al=1:1.875, the thermal decomposition temperature range overlaps, the heat absorption efficiency reaches 980J / g, and flame retardant synergy is achieved. 0.03 parts of platinum catalyst and 1.0 parts of peroxide increase the crosslinking density to 3.2×10 -4 mol / cm 3 , achieving vulcanization synergy; 20 parts of fumed silica and 2 parts of vinyl silane with a grafting rate of 92%, achieving interface synergy;

[0123] During the process, plasma treatment for 30 minutes reduced the surface energy of the filler to 28 mN / m, and achieved a SiO2 dispersion index of 0.21 at a centrifugal force of 2000 g. At the same time, LOI was 38.5%, which was better than 36.8% in Example 2, a tear strength of 18.3 kN / m, which was better than 17.2% in Example 3, and a thermal weight loss of 4.8%, which was better than 4.9% in Example 5, reaching the peak of comprehensive performance. Therefore, Example 1 is the best embodiment of the present invention.

[0124] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0125] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flame-retardant silicone rubber composite material comprising a matrix polymer, a reinforcing filler, a compounded flame retardant system, an enhanced protection system, a cross-linking system, and a processing aid, characterized in that: The matrix polymer is composed of the following raw materials in parts by weight: vinyl-terminated polydimethylsiloxane: 100 parts; The reinforcing filler is composed of the following raw materials in parts by weight: fumed silica: 15-25 parts; The composite flame retardant system is composed of the following raw materials in parts by weight: Aluminum hydroxide: 30-45 parts; Magnesium hydroxide: 15-25 parts; The ratio of magnesium hydroxide to aluminum hydroxide is 1:(1.5-2.0); Sodium tetraborate decahydrate: 5-10 parts; Tris(β-chloroethyl) phosphate: 3-8 parts; The enhanced protection system is composed of the following raw materials in parts by weight: End-hydrogenated polymethylsiloxane: 2-5 parts; Vinyltrimethoxysilane: 1-3 parts; The cross-linking system is composed of the following raw materials in parts by weight: 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane: 0.5-1.5 parts; Platinum complex catalyst: 0.01-0.05 parts; The processing aid is composed of the following raw materials in parts by weight: Structure control agent: 1-3 parts; The structure control agent is one of diphenylsilanediol or hexamethyldisilazane; Heat-resistant additives: 1-3 parts.

2. The flame retardant silicone rubber composite material according to claim 1, characterized in that: The tris(β-chloroethyl) phosphate is prepared by dispersing ammonium polyphosphate with a degree of polymerization greater than 1000 in an aqueous solution containing 1-3 wt% of an alkylnaphthalene sulfonate formaldehyde condensate, adding dropwise a wall material solution consisting of a melamine-formaldehyde prepolymer and 5-8 wt% of carboxymethyl cellulose at a temperature of 40-60° C. and a shear rate of 3000-5000 rpm, and subjecting the mixture to in-situ polymerization in an acidic environment of pH 3.5-4.0 for 2-4 hours. The microcapsule has an encapsulation rate of ≥92% and a purity of ≥99.0%.

3. The flame retardant silicone rubber composite material according to claim 2, characterized in that: The sodium tetraborate decahydrate is prepared by placing industrial sodium tetraborate decahydrate in a plasma enhanced chemical vapor deposition furnace, introducing hexamethyldisiloxane vapor under a vacuum of 0.1-1.0 kPa and a temperature of 300-400° C. for surface hydrophobic deposition for 20-30 minutes. The product has a contact angle of >120° and a purity of >98.5%.

4. The flame retardant silicone rubber composite material according to claim 1, characterized in that: The platinum complex catalyst is prepared by chelating chloroplatinic acid and vinyl-containing cage-type silsesquioxane in a toluene solution at 80-100° C. for 6-8 hours under nitrogen protection, and then removing the solvent and small molecular byproducts through molecular distillation. The platinum content is 3.0-3.5 wt%.

5. The flame retardant silicone rubber composite material according to claim 4, characterized in that: The fumed silica is prepared by subjecting untreated fumed silica to vapor-phase surface grafting by atomizing and spraying a mixture of hexamethyldisilazane and dimethyldiethoxysilane in a mass ratio of 1:2 in a fluidized bed reactor at 200-250° C. and a negative pressure of -0.08 to -0.05 MPa.

6. The flame retardant silicone rubber composite material according to claim 4, characterized in that: The heat-resistant additive is prepared by dissolving ammonium cerium nitrate in a mixture of ethylene glycol and citric acid at a molar ratio of 1:1.5, pressurizing to 1.5-2.0 MPa in a hydrothermal reactor at 160-180° C. for reaction for 12-16 hours to generate monodisperse cubic cerium oxide nanoparticles with an average particle size of 15±3 nm and a purity of ≥99.95%.

7. The flame retardant silicone rubber composite material according to claim 1, characterized in that: The hydrogen-terminated polymethylsiloxane is prepared by anionic ring-opening polymerization of octamethylcyclotetrasiloxane and 1,3,5,7-tetramethylcyclotetrasiloxane under a dynamic vacuum of less than 100 Pa and at 80°C, using tetramethylammonium hydroxide as a catalyst and precisely controlling the feeding sequence of the chain terminator tetramethyldihydrogendisiloxane. The hydrogen content is 0.18-0.22wt%, the molecular weight distribution index is ≤1.15, and the purity is ≥99.5%.

8. The flame retardant silicone rubber composite material according to claim 1, characterized in that: The silane coupling agent is prepared by exposing vinyltrimethoxysilane and nano-titanium dioxide aerosol with a particle size of 20-30 nm to dielectric barrier discharge plasma for 15-20 minutes under ultrasonic radiation and argon atmosphere to achieve directional activation of silane molecules.

9. The method for preparing a flame-retardant silicone rubber composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Flame retardant filler plasma activation pretreatment: Aluminum hydroxide (30-45 parts) and magnesium hydroxide (15-25 parts) are added to the twin-screw feeding bin in proportion; radio frequency plasma is activated in the second section of the screw barrel, and sodium tetraborate decahydrate (5-10 parts) and vinyltrimethoxysilane (1-3 parts) are sprayed in by atomization; surface chemical grafting is completed under a vacuum environment, and the outlet material is tested by a laser particle size analyzer. S2: High shear dispersion of matrix composite slurry: Vinyl-terminated polydimethylsiloxane (100 parts), hydrogen-terminated polymethylsiloxane (2-5 parts), and a structure control agent (1-3 parts) are pumped into a central distributor of a reactor; the liquid phase is flung toward the packing layer using a centrifugal force of 2000 g, and fumed silica (15-25 parts) and the activated flame-retardant filler obtained in step S1 are simultaneously injected; nanodispersion is completed under high-speed rotation, and the Stormer viscosity of the slurry is measured; S3: Microfluidic dispersion of nano-functional additives: The slurry obtained in step S2 is premixed with tris(β-chloroethyl) phosphate (3-8 parts) and a heat-resistant additive (1-3 parts) and then pumped into a storage tank; large particle agglomerates are crushed under a first-stage pressure of 120 MPa; nanoparticles are allowed to penetrate the gaps between siloxane molecular chains under an ultrahigh pressure of 180 MPa, and the zeta potential of the slurry is detected online; S4: Two-component isolation packaging: 70% of the total slurry was transferred to the component A tank, and a platinum catalyst (0.01-0.05 parts) was added and homogenized in a static mixer. The mixing temperature of component A was 20±1°C. The remaining 30% of the slurry was transferred to the component B tank and mixed with 2,5-bis(tert-butylperoxide)-2,5-dimethylhexane (0.5-1.5 parts). The mixing temperature of component B was 22±1°C. The slurry was then dispensed simultaneously using a dual-channel filling head in an environment with an oxygen content of <1ppm. The mass ratio error of components A and B was ≤0.3%. S5: Field-assisted step curing: The AB components are extruded and coated on the sealing surface in a 1:1 ratio and placed in an alternating magnetic field to arrange the fillers in an orderly manner along the stress direction; medium-wave infrared is activated to melt the matrix and penetrate the interface; under short-wave infrared, the synergistic reaction of platinum-catalyzed hydrosilylation and peroxide cross-linking is triggered to detect the curing depth.

10. The method for preparing a flame-retardant silicone rubber composite material according to claim 9, characterized in that: In step S5, the alternating magnetic field strength is 15 kA / m to induce directional alignment for 10 minutes; the medium-wave infrared power density is 4 W / cm 2 , gradient heating to 100℃; short-wave infrared power density 8W / cm 2 Fast curing up to 160°C.

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