Fire-resistant silicone rubber, preparation method thereof and cable

Abstract

The invention relates to the technical field of cables, in particular to fire-resistant silicone rubber, a preparation method thereof and a cable, and the fire-resistant silicone rubber is composed of a matrix resin composite system, a composite flame-retardant system, a nanometer enhancement and smoke suppression system and an interface and vulcanization system, the matrix resin composite system comprises methyl vinyl silicone rubber, vinyl silicone rubber and macromolecular polyethylene, the composite flame-retardant system comprises nano aluminum hydroxide, zinc borate and transition metal nitride, and the nano enhancement and smoke suppression system comprises modified nano silicon dioxide, organic montmorillonite and zinc molybdate. The interface and vulcanization system comprises a silane coupling agent, dicumyl peroxide and a platinum catalyst. Therefore, the problems that in the prior art, fire resistance is insufficient, toxic gas is released during combustion, the mechanical property is poor, machining is complex, and environment friendliness is low are solved.

Description

Technical Field

[0001] The invention relates to the technical field of cables, and in particular to a fire-resistant silicone rubber and a preparation method thereof and a cable. Background Art

[0002] With the growing demand for electricity in modern society, the safety and reliability of cables as the key carrier of power transmission are of vital importance. In many cable application scenarios, such as high-rise buildings, underground tunnels, mines, etc., there are great fire hazards. Once a fire occurs, the burning of cables will not only cause power supply interruption, but also release a large amount of toxic and harmful gases, aggravating the fire hazard and threatening the safety of life and property.

[0003] Although traditional silicone rubber materials have good flexibility, high and low temperature resistance and electrical insulation performance, they are obviously insufficient in fire resistance. When encountering a fire, ordinary silicone rubber is easy to burn, and dripping will be produced during the combustion process, further promoting the spread of the fire. Some fire-resistant rubber materials on the market often improve their fire resistance by adding a large amount of flame retardants, but this may have a negative impact on other properties of the rubber, such as mechanical properties and processing properties, resulting in a decline in the overall performance of the material and an inability to meet the increasingly stringent cable use requirements. Summary of the invention

[0004] The present application provides a fire-resistant silicone rubber and a preparation method and a cable thereof, so as to solve the problems in the prior art of insufficient fire resistance, release of toxic gases during combustion, poor mechanical properties, complex processing and low environmental protection.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present invention is as follows: The present invention provides a fire-resistant silicone rubber, which is composed of a matrix resin composite system, a composite flame retardant system, a nano-reinforcement and smoke suppression system, and an interface and vulcanization system, wherein the matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-reinforcement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

[0006] Furthermore, the matrix resin composite system comprises the following components in parts by weight: Methyl vinyl silicone rubber: 100-120 parts; Vinyl silicone rubber: 30-50 parts; High molecular weight polyethylene: 5-10 parts.

[0007] Furthermore, the composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 40-60 parts; Zinc borate: 10-15 parts; Transition metal nitride: 5-10 parts.

[0008] Furthermore, the particle size of the nano aluminum hydroxide is 80-100 nm, and the transition metal nitride is one or more combinations of titanium nitride, zirconium nitride, and molybdenum nitride.

[0009] Furthermore, the nano-enhancement and smoke suppression system comprises the following components by weight: Modified nano silicon dioxide: 15-20 parts; Organic montmorillonite: 5-8 parts; Zinc molybdate: 3-5 parts.

[0010] Furthermore, the modified nano-silica is polymethyl methacrylate grafted nano-silica.

[0011] Furthermore, the interface and vulcanization system comprises the following components in parts by weight: Silane coupling agent: 3-5 parts; Dicumyl peroxide: 1-2 parts; Platinum catalyst: 0.1-0.3 parts.

[0012] The present application also proposes a method for preparing fire-resistant silicone rubber, comprising the following steps: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; Add the prepared matrix resin composite system into an open mixing mill and pass it through 3-5 times at 50-60°C for plasticization; Add the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and mix at 60-70° C. and 30-40 r / min for 10-15 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 70-80°C for 20-30 minutes, during which the rubber is turned over every 6-8 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 45-55°C for 5-10 minutes; Put the mixed rubber into a mold preheated to 100-120℃, first vulcanize at 80-100℃ and 6-8MPa for 10-15 minutes, then heat to 160-180℃ at a heating rate of 6-8℃ / min, and vulcanize at 18-22MPa for 15-30 minutes. During the vulcanization process, exhaust the air every 5-10 minutes. After the molding vulcanization is completed, the product is cooled to 40-50°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

[0013] Furthermore, the preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene in a high-speed mixer at 70-80°C for 15-20 minutes, and the mixing speed is 200-300r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 300-400r / min for 2-3 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano silicon dioxide, organic montmorillonite and zinc molybdate in a twin-screw extruder at 120-130°C, and the screw speed is 100-150r / min.

[0014] The present application also proposes a cable, comprising a conductor and an insulating layer wrapped around the conductor, wherein the insulating layer is made of fire-resistant silicone rubber.

[0015] The beneficial effects achieved by adopting the above-mentioned present invention are as follows: 1. The present invention prepares a fire-resistant silicone rubber, which realizes a triple flame retardant mechanism of heat absorption and cooling, carbonization barrier and ceramic enhancement through a ternary composite flame retardant system of nano aluminum hydroxide-zinc borate-transition metal nitride. Nano aluminum hydroxide dehydrates and absorbs heat to reduce the flame temperature, thereby reducing the peak heat release rate by 40%. Zinc borate forms a glassy protective layer to delay heat transfer. Transition metal nitrides are converted into a ceramic phase at high temperatures to enhance the strength of the carbon layer. The three work together to form a three-dimensional network, so that the oxygen index reaches 32-38%, and the combustion dripping level reaches FV-0 (no dripping), which effectively solves the safety hazards of traditional silicone rubber that is easy to burn and dripping to help combustion; 2. At the same time, the modified nano-silica-organic montmorillonite-zinc molybdate reinforcement system significantly improves the mechanical properties and thermal stability of the material through the nano-scale interface synergistic effect. Polymethyl methacrylate grafted nano-silica entangles with the silicone rubber molecular chain through hydrogen bonds, forming a "pinning effect" to hinder crack propagation, and forms a nano-scale reinforcement network with organic montmorillonite through physical filling and chemical cross-linking to achieve a balance between rigidity and flexibility. The high molecular weight polyethylene crystalline structure forms an interpenetrating network with silicone rubber, which increases the thermal decomposition temperature from 300°C to 380°C. Zinc molybdate and nano-aluminum hydroxide synergistically catalyze carbonization, which increases the density of the carbon layer, which not only improves the tensile strength and elongation at break of the material, but also solves the problem of easy degradation of traditional silicone rubber at high temperatures; 3. The present invention adopts a gradient temperature vulcanization process combined with intelligent interface control to solve the problems of long vulcanization time and high energy consumption in traditional processes. The pre-vulcanization stage (80-100°C) promotes the initial dispersion of the filler, and the compression vulcanization (160-180°C) eliminates bubble defects through dynamic exhaust, shortening the vulcanization time by 30%. The silane coupling agent forms -Si-O-Si- bonds on the surface of the nanofiller, which increases the dispersion of the filler by 50% and improves the dispersibility of the nanofiller. The platinum catalyst accelerates the addition reaction of Si-H and vinyl, and increases the crosslinking density, which not only shortens the vulcanization time, but also improves the production yield, achieving efficient and stable production; 4. The present invention reduces the overall material cost and prolongs the service life through nano material enhancement and process optimization. The use of halogen-free components such as nitride and boron avoids secondary pollution. The synergistic flame retardancy of nano aluminum hydroxide and zinc borate and the inhibition of toxic gas diffusion by the nitride ceramic carbon layer achieve environmental protection goals; 5. When used as a cable insulation layer, the silicone rubber of the present invention exhibits extreme environmental adaptability. It can remain unbroken for 180 minutes under a 950°C flame, ensuring continuous power supply in fire scenarios. By adjusting the type of transition metal nitride, it can adapt to the full voltage level cable requirements of 1kV-35kV, and the oil and ozone resistance are improved by 50%, making it suitable for high-risk scenarios such as underground tunnels and mines, filling the technical gap in existing fire-resistant cable materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 A schematic diagram of the structure of a cable provided in one embodiment of the present invention; Figure 2 A microscopic schematic diagram of the fire-resistant silicone rubber provided in Example 1 of the present invention; Figure 3 A microscopic schematic diagram of the fire-resistant silicone rubber provided in Example 2 of the present invention; Figure 4 A microscopic schematic diagram of the fire-resistant silicone rubber provided in Example 3 of the present invention; Figure 5 A microscopic schematic diagram of the fire-resistant silicone rubber provided in Example 4 of the present invention; Figure 6 This is a microscopic schematic diagram of the fire-resistant silicone rubber provided in Example 5 of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0018] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0019] A fire-resistant silicone rubber and its preparation method and cable of the embodiment of the present application are described below with reference to the accompanying drawings. In view of the low performance problem mentioned in the above background technology, the present application provides a fire-resistant silicone rubber. In this method, a ternary composite flame retardant system composed of nano aluminum hydroxide, zinc borate and transition metal nitride is used to realize the triple flame retardant mechanism of heat absorption and cooling, carbonization barrier and ceramic enhancement, which significantly improves the flame retardant performance; secondly, the reinforcement system composed of modified nano silicon dioxide, organic montmorillonite and zinc molybdate greatly enhances the mechanical properties and thermal stability of the material through the nano-level interface synergistic effect, and achieves a rigid-flexible balance. Furthermore, the gradient temperature vulcanization process combined with intelligent interface regulation effectively shortens the vulcanization time, reduces energy consumption, and improves production efficiency and yield rate. In addition, through nano material enhancement and process optimization, the comprehensive cost of materials is reduced, and halogen-free components are used to meet environmental protection requirements. Finally, as a cable insulation layer, the silicone rubber exhibits excellent adaptability to extreme environments. As a result, the problems of insufficient fire resistance, release of toxic gases during combustion, poor mechanical properties, complex processing and low environmental protection in the prior art are solved.

[0020] The present invention is further described in conjunction with the following examples.

[0021] Example 1 A fire-resistant silicone rubber consists of a matrix resin composite system, a composite flame retardant system, a nano-enhancement and smoke suppression system, and an interface and vulcanization system. The matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-enhancement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

[0022] In the embodiment of the present application, the matrix resin composite system includes the following components by weight: Methyl vinyl silicone rubber: 100 parts; Vinyl silicone rubber: 30 parts; Polyethylene polymer: 5 parts.

[0023] In the embodiments of the present application, the composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 40 parts; Zinc borate: 10 parts; Transition metal nitride: 5 parts.

[0024] The particle size of the nano aluminum hydroxide is 80-100 nm, and the transition metal nitride is titanium nitride.

[0025] In the embodiments of the present application, the nano-enhancement and smoke suppression system comprises the following components by weight: Modified nano-silicon dioxide: 15 parts; Organic montmorillonite: 5 parts; Zinc molybdate: 3 parts.

[0026] Wherein, the modified nano-silica is polymethyl methacrylate grafted nano-silica.

[0027] In the embodiments of the present application, the interface and vulcanization system includes the following components by weight: Silane coupling agent: 3 parts; Dicumyl peroxide: 1 part; Platinum catalyst: 0.1 parts.

[0028] The present application also proposes a method for preparing fire-resistant silicone rubber, comprising the following steps: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; The prepared matrix resin composite system was added into an open mill and plasticized by passing it through a thin mill for 3 times at 50°C. Add the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and mix at 60° C. and 30 r / min for 10 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 70°C for 20 minutes, during which the rubber is turned over every 6 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 45°C for 5 minutes; Put the mixed rubber into a mold preheated to 100℃, first vulcanize at 80℃ and 6MPa for 10 minutes, then heat to 160℃ at a heating rate of 6℃ / min, and vulcanize at 18MPa for 15 minutes. During the vulcanization process, exhaust the air every 5 minutes. After the molding vulcanization is completed, the product is cooled to 40°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

[0029] In an embodiment of the present application, the preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular weight polyethylene in a high-speed mixer at 70°C for 15 minutes, and the mixing speed is 200r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 300r / min for 2 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano silicon dioxide, organic montmorillonite and zinc molybdate in a twin-screw extruder at 120°C, and the screw speed is 100r / min.

[0030] The present application also proposes a cable, such as Figure 1 As shown, it includes a conductor and an insulating layer wrapped outside the conductor, and the insulating layer is made of fire-resistant silicone rubber.

[0031] Example 2 A fire-resistant silicone rubber consists of a matrix resin composite system, a composite flame retardant system, a nano-enhancement and smoke suppression system, and an interface and vulcanization system. The matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-enhancement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

[0032] In the embodiment of the present application, the matrix resin composite system includes the following components by weight: Methyl vinyl silicone rubber: 105 parts; Vinyl silicone rubber: 35 parts; High molecular weight polyethylene: 6 parts.

[0033] In the embodiments of the present application, the composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 45 parts; Zinc borate: 11 parts; Transition metal nitride: 6 parts.

[0034] The particle size of the nano aluminum hydroxide is 80-100 nm, and the transition metal nitride is zirconium nitride.

[0035] In the embodiments of the present application, the nano-enhancement and smoke suppression system comprises the following components by weight: Modified nano-silicon dioxide: 16 parts; Organic montmorillonite: 6 parts; Zinc molybdate: 3.5 parts.

[0036] Wherein, the modified nano-silica is polymethyl methacrylate grafted nano-silica.

[0037] In the embodiments of the present application, the interface and vulcanization system includes the following components by weight: Silane coupling agent: 3.5 parts; Dicumyl peroxide: 1.2 parts; Platinum catalyst: 0.15 parts.

[0038] The present application also proposes a method for preparing fire-resistant silicone rubber, comprising the following steps: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; The prepared matrix resin composite system was added into an open mill and plasticized by passing it through a thin mill three times at 52°C. Add the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and mix at 62° C. and 32 r / min for 11 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 72°C for 22 minutes, during which the rubber is turned over every 6 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 47°C for 6 minutes; The mixed rubber compound was placed in a mold preheated to 105°C, and initially vulcanized at 85°C and 6MPa for 11 minutes, then heated to 165°C at a heating rate of 6°C / min, and vulcanized at 19MPa for 18 minutes. During the vulcanization process, exhaust was performed every 6 minutes. After the molding vulcanization is completed, the product is cooled to 42°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

[0039] In an embodiment of the present application, the preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular weight polyethylene in a high-speed mixer at 72°C for 16 minutes, and the mixing speed is 220r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 320r / min for 2.2 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano silicon dioxide, organic montmorillonite and zinc molybdate in a twin-screw extruder at 122°C, and the screw speed is 110r / min.

[0040] The present application also proposes a cable, comprising a conductor and an insulating layer wrapped around the conductor, wherein the insulating layer is made of fire-resistant silicone rubber.

[0041] Example 3 A fire-resistant silicone rubber consists of a matrix resin composite system, a composite flame retardant system, a nano-enhancement and smoke suppression system, and an interface and vulcanization system. The matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-enhancement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

[0042] In the embodiment of the present application, the matrix resin composite system includes the following components by weight: Methyl vinyl silicone rubber: 110 parts; Vinyl silicone rubber: 40 parts; High molecular weight polyethylene: 7 parts.

[0043] In the embodiments of the present application, the composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 50 parts; Zinc borate: 12 parts; Transition metal nitride: 7 parts.

[0044] Wherein, the particle size of nano aluminum hydroxide is 80-100nm, and the transition metal nitride is molybdenum nitride.

[0045] In the embodiments of the present application, the nano-enhancement and smoke suppression system comprises the following components by weight: Modified nano silicon dioxide: 18 parts; Organic montmorillonite: 7 parts; Zinc molybdate: 4 parts.

[0046] Wherein, the modified nano-silica is polymethyl methacrylate grafted nano-silica.

[0047] In the embodiments of the present application, the interface and vulcanization system includes the following components by weight: Silane coupling agent: 4 parts; Dicumyl peroxide: 1.5 parts; Platinum catalyst: 0.2 parts.

[0048] The present application also proposes a method for preparing fire-resistant silicone rubber, comprising the following steps: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; The prepared matrix resin composite system was added into an open mill and plasticized by passing it through a thin mill for 4 times at 55°C. Adding the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and kneading at 65° C. and 35 r / min for 12 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 75°C for 25 minutes, during which the rubber is turned over every 7 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 50°C for 7 minutes; The mixed rubber compound was placed in a mold preheated to 110°C, and initially vulcanized at 90°C and 7MPa for 12 minutes, then heated to 170°C at a heating rate of 7°C / min, and press-cured at 20MPa for 22 minutes. During the press-curing process, exhaust was performed every 7 minutes. After the molding vulcanization is completed, the product is cooled to 45°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

[0049] In an embodiment of the present application, the preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular weight polyethylene in a high-speed mixer at 75°C for 17 minutes, and the mixing speed is 250r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 350r / min for 2.5 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano silicon dioxide, organic montmorillonite and zinc molybdate in a twin-screw extruder at 125°C, and the screw speed is 130r / min.

[0050] The present application also proposes a cable, comprising a conductor and an insulating layer wrapped around the conductor, wherein the insulating layer is made of fire-resistant silicone rubber.

[0051] Example 4 A fire-resistant silicone rubber consists of a matrix resin composite system, a composite flame retardant system, a nano-enhancement and smoke suppression system, and an interface and vulcanization system. The matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-enhancement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

[0052] In the embodiment of the present application, the matrix resin composite system includes the following components by weight: Methyl vinyl silicone rubber: 115 parts; Vinyl silicone rubber: 45 parts; High molecular weight polyethylene: 9 parts.

[0053] In the embodiments of the present application, the composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 55 parts; Zinc borate: 14 parts; Transition metal nitride: 9 parts.

[0054] The particle size of the nano aluminum hydroxide is 80-100 nm, and the transition metal nitride is a combination of zirconium nitride and molybdenum nitride.

[0055] In the embodiments of the present application, the nano-enhancement and smoke suppression system comprises the following components by weight: Modified nano-silicon dioxide: 19 parts; Organic montmorillonite: 7 parts; Zinc molybdate: 4.5 parts.

[0056] Wherein, the modified nano-silica is polymethyl methacrylate grafted nano-silica.

[0057] In the embodiments of the present application, the interface and vulcanization system includes the following components by weight: Silane coupling agent: 4.5 parts; Dicumyl peroxide: 1.8 parts; Platinum catalyst: 0.25 parts.

[0058] The present application also proposes a method for preparing fire-resistant silicone rubber, comprising the following steps: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; The prepared matrix resin composite system was added into an open mill and plasticized by passing it through a thin mill for 4 times at 58°C. Adding the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and kneading at 68° C. and 38 r / min for 14 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 78°C for 28 minutes, during which the rubber is turned over every 8 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 52°C for 8 minutes; The mixed rubber compound was placed in a mold preheated to 115°C, and initially vulcanized at 95°C and 7MPa for 14 minutes, then heated to 175°C at a heating rate of 7°C / min, and press-cured at 21MPa for 27 minutes. During the press-curing process, exhaust was performed every 8 minutes. After the molding vulcanization is completed, the product is cooled to 48°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

[0059] In an embodiment of the present application, the preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular weight polyethylene in a high-speed mixer at 78°C for 19 minutes, and the mixing speed is 280r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 380r / min for 3 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano-silica, organic montmorillonite and zinc molybdate in a twin-screw extruder at 128°C, and the screw speed is 140r / min.

[0060] The present application also proposes a cable, comprising a conductor and an insulating layer wrapped around the conductor, wherein the insulating layer is made of fire-resistant silicone rubber.

[0061] Example 5 A fire-resistant silicone rubber consists of a matrix resin composite system, a composite flame retardant system, a nano-enhancement and smoke suppression system, and an interface and vulcanization system. The matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-enhancement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

[0062] In the embodiment of the present application, the matrix resin composite system includes the following components by weight: Methyl vinyl silicone rubber: 120 parts; Vinyl silicone rubber: 50 parts; Polyethylene polymer: 10 parts.

[0063] In the embodiments of the present application, the composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 60 parts; Zinc borate: 15 parts; Transition metal nitride: 10 parts.

[0064] The particle size of the nano aluminum hydroxide is 80-100 nm, and the transition metal nitride is a combination of titanium nitride and zirconium nitride.

[0065] In the embodiments of the present application, the nano-enhancement and smoke suppression system comprises the following components by weight: Modified nano-silicon dioxide: 20 parts; Organic montmorillonite: 8 parts; Zinc molybdate: 5 parts.

[0066] Wherein, the modified nano-silica is polymethyl methacrylate grafted nano-silica.

[0067] In the embodiments of the present application, the interface and vulcanization system includes the following components by weight: Silane coupling agent: 5 parts; Dicumyl peroxide: 2 parts; Platinum catalyst: 0.3 parts.

[0068] The present application also proposes a method for preparing fire-resistant silicone rubber, comprising the following steps: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; The prepared matrix resin composite system was added into an open mill and plasticized by thin passing 5 times at 60°C; Adding the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and kneading at 70° C. and 40 r / min for 15 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 80°C for 30 minutes, during which the rubber is turned over every 8 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 55°C for 10 minutes; Put the mixed rubber into a mold preheated to 120℃, first vulcanize at 100℃ and 8MPa for 15 minutes, then heat to 180℃ at a heating rate of 8℃ / min, and vulcanize at 22MPa for 30 minutes. During the vulcanization process, exhaust the air every 10 minutes. After the molding vulcanization is completed, the product is cooled to 50°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

[0069] In an embodiment of the present application, the preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular weight polyethylene in a high-speed mixer at 80°C for 20 minutes, and the mixing speed is 300r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 400r / min for 3 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano-silica, organic montmorillonite and zinc molybdate in a twin-screw extruder at 130°C, and the screw speed is 150r / min.

[0070] The present application also proposes a cable, comprising a conductor and an insulating layer wrapped around the conductor, wherein the insulating layer is made of fire-resistant silicone rubber.

[0071] Comparative Example 1 A fire-resistant silicone rubber, which differs from Example 1 only in that transition metal nitride and zinc borate in the composite flame retardant system are not added, and the reduced amount of transition metal nitride and zinc borate is distributed to nano aluminum hydroxide. The remaining materials and preparation methods are the same as those of Example 1.

[0072] Comparative Example 2 A fire-resistant silicone rubber, which differs from Example 1 only in that no nano-reinforcement and smoke suppression system is added, and the reduced amount of the nano-reinforcement and smoke suppression system is distributed to the matrix resin composite system. The remaining materials and preparation methods are the same as those of Example 1.

[0073] Comparative Example 3 A fire-resistant silicone rubber, which differs from Example 1 only in that a traditional vulcanization process is adopted, all components are directly added to an open mill, and mixed at room temperature for 30 minutes; a single temperature (160° C.) is used for compression vulcanization for 30 minutes in the vulcanization stage, without gradient heating and exhaust operations, and the remaining materials are the same as those in Example 1.

[0074] Performance Testing The test is carried out according to GB / T2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method Part 2: Room Temperature Test". The samples of Examples 1-5 and Comparative Examples 1-3 are fixed vertically in the combustion tube, and a mixed flow of oxygen and nitrogen is introduced from the bottom to maintain stable combustion after the samples are ignited. The minimum oxygen concentration required to just maintain the combustion of the samples is measured, and the oxygen index is expressed as the volume percentage of the oxygen content. The test is carried out according to GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The prepared dumbbell-shaped sample is clamped on a tensile testing machine, and a tensile force is applied to the sample at a specified tensile speed. The maximum tensile force when the sample breaks is recorded, and the tensile strength is calculated based on the initial cross-sectional area of ​​the sample. A sample of a certain mass is placed in a thermogravimetric analyzer, heated at a certain heating rate, and the change in the sample mass with temperature is recorded. The thermal decomposition temperature is usually taken as the temperature when the mass loss begins to increase significantly. The results are shown in Table 1 below.

[0075] Table 1 Test results of fire-resistant silicone rubber properties Oxygen index (%) Tensile strength (Mpa) Thermal decomposition temperature (℃) Production efficiency (kg / h) Environmental protection Example 1 32 7.8 380 1200 conform to Example 2 33 8.0 382 1220 conform to Example 3 35 8.2 385 1260 conform to Example 4 38 8.5 390 1300 conform to Example 5 37 8.4 388 1280 conform to Comparative Example 1 24 7.2 350 1100 Not Compliant Comparative Example 2 30 5.5 340 1200 conform to Comparative Example 3 32 7.0 360 800 conform to Depend on Figure 2-Figure 6 As shown in Table 1, the oxygen index, tensile strength, thermal decomposition temperature, thermal stability and production efficiency of the refractory silicone rubber in the embodiment of the present invention are significantly higher than those in the comparative example, indicating that the refractory silicone rubber of the present invention has excellent properties such as high oxygen index, tensile strength, thermal decomposition temperature, thermal stability and production efficiency, and can achieve low-cost large-scale production.

[0076] By adopting the preparation method of the fire-resistant silicone rubber provided by the present invention, the oxygen index, tensile strength, thermal decomposition temperature, thermal stability and production efficiency of Example 4 are optimal, wherein the oxygen index reaches 38%, the tensile strength reaches 8.5MPa, the thermal decomposition temperature reaches 390°C, and the production efficiency reaches 1300kg / h. It can be seen that the introduced materials need to be within a certain amount, and adding too much or too little will affect the performance; while the performance of Comparative Examples 1, 2 and 3 is relatively poor, and there is no obvious difference. Therefore, considering the comprehensive performance of the fire-resistant silicone rubber, the fire-resistant silicone rubber of the present invention can achieve strong tensile strength, improve the excellent performance such as thermal decomposition temperature under green, environmentally friendly and non-toxic conditions, while reducing the cost, and the preparation process is simple and operable.

[0077] The embodiment of the present application provides a fire-resistant silicone rubber, in which a ternary composite flame retardant system composed of nano aluminum hydroxide, zinc borate and transition metal nitride is used to realize the triple flame retardant mechanism of heat absorption and cooling, carbonization barrier and ceramic enhancement, which significantly improves the flame retardant performance; secondly, the enhanced system composed of modified nano silicon dioxide, organic montmorillonite and zinc molybdate greatly enhances the mechanical properties and thermal stability of the material through the nano-level interface synergistic effect, and achieves a rigid-flexible balance. Furthermore, the gradient temperature rise vulcanization process combined with intelligent interface regulation effectively shortens the vulcanization time, reduces energy consumption, and improves production efficiency and yield rate. In addition, through nano material enhancement and process optimization, the comprehensive cost of materials is reduced, and halogen-free components are used to meet environmental protection requirements. Finally, as a cable insulation layer, the silicone rubber exhibits excellent adaptability to extreme environments. As a result, the problems of insufficient fire resistance, release of toxic gases during combustion, poor mechanical properties, complex processing and low environmental protection in the prior art are solved.

[0078] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A fire-resistant silicone rubber, characterized in that: The fire-resistant silicone rubber is composed of a matrix resin composite system, a composite flame retardant system, a nano-reinforcement and smoke suppression system, and an interface and vulcanization system. The matrix resin composite system includes methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene, the composite flame retardant system includes nano aluminum hydroxide, zinc borate and transition metal nitride, the nano-reinforcement and smoke suppression system includes modified nano silicon dioxide, organic montmorillonite and zinc molybdate, and the interface and vulcanization system includes a silane coupling agent, diisopropylbenzene peroxide and a platinum catalyst.

2. A fire-resistant silicone rubber according to claim 1, characterized in that: The matrix resin composite system comprises the following components by weight: Methyl vinyl silicone rubber: 100-120 parts; Vinyl silicone rubber: 30-50 parts; High molecular weight polyethylene: 5-10 parts.

3. A fire-resistant silicone rubber according to claim 2, characterized in that: The composite flame retardant system comprises the following components by weight: Nano aluminum hydroxide: 40-60 parts; Zinc borate: 10-15 parts; Transition metal nitride: 5-10 parts.

4. A fire-resistant silicone rubber according to claim 3, characterized in that: The particle size of the nano aluminum hydroxide is 80-100 nm, and the transition metal nitride is one or more combinations of titanium nitride, zirconium nitride and molybdenum nitride.

5. A fire-resistant silicone rubber according to claim 1, characterized in that: The nano enhancement and smoke suppression system comprises the following components by weight: Modified nano silicon dioxide: 15-20 parts; Organic montmorillonite: 5-8 parts; Zinc molybdate: 3-5 parts.

6. A fire-resistant silicone rubber according to claim 5, characterized in that: The modified nano-silica is polymethyl methacrylate grafted nano-silica.

7. The fire-resistant silicone rubber according to claim 1, characterized in that: The interface and vulcanization system comprises the following components by weight: Silane coupling agent: 3-5 parts; Dicumyl peroxide: 1-2 parts; Platinum catalyst: 0.1-0.3 parts.

8. A method for preparing the fire-resistant silicone rubber according to any one of claims 1 to 7, characterized in that: The following steps are involved: The matrix resin composite system, composite flame retardant system, nano-enhancement and smoke suppression system, interface and vulcanization system are prepared respectively; Add the prepared matrix resin composite system into an open mixing mill and pass it through 3-5 times at 50-60°C for plasticization; Add the silane coupling agent in the interface and vulcanization system to the plasticized matrix resin composite system, and mix at 60-70° C. and 30-40 r / min for 10-15 minutes; Add the composite flame retardant system, nano-enhancement and smoke suppression system in sequence, and continue mixing at 70-80°C for 20-30 minutes, during which the rubber is turned over every 6-8 minutes; Add dicumyl peroxide and platinum catalyst in the interface and vulcanization system, and mix at 45-55°C for 5-10 minutes; Put the mixed rubber into a mold preheated to 100-120℃, first vulcanize at 80-100℃ and 6-8MPa for 10-15 minutes, then heat to 160-180℃ at a heating rate of 6-8℃ / min, and vulcanize at 18-22MPa for 15-30 minutes. During the vulcanization process, exhaust the air every 5-10 minutes. After the molding vulcanization is completed, the product is cooled to 40-50°C in the mold and then taken out to obtain the fire-resistant silicone rubber.

9. The method for preparing a fire-resistant silicone rubber according to claim 8, characterized in that: The preparation method of the matrix resin composite system is to mix methyl vinyl silicone rubber, vinyl silicone rubber and high molecular polyethylene in a high-speed mixer at 70-80°C for 15-20 minutes, and the mixing speed is 200-300r / min; the preparation method of the composite flame retardant system is to ball mill nano aluminum hydroxide, zinc borate and transition metal nitride in a ball mill at a speed of 300-400r / min for 2-3 hours to fully mix the components; the preparation method of the nano-enhancement and smoke suppression system is to blend and extrude modified nano silicon dioxide, organic montmorillonite and zinc molybdate in a twin-screw extruder at 120-130°C, and the screw speed is 100-150r / min.

10. A cable, characterized in that: It comprises a conductor and an insulating layer wrapped around the conductor, wherein the insulating layer is made of the fire-resistant silicone rubber according to any one of claims 1 to 7.

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