A flame retardant rubber composition and preparation method thereof

Abstract

The present invention belongs to the field of rubber technology, and specifically discloses a flame retardant rubber composition and a preparation method thereof. The raw materials of the flame retardant rubber composition include: butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant, antioxidant, sulfur, accelerator, white carbon black, cross-linking auxiliary agent, and flame retardant for rubber. The flame retardant rubber composition prepared by the present invention not only has good flame retardant properties, but also has good mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber, and in particular relates to a flame retardant rubber composition and a preparation method thereof. Background Art

[0002] As the basic raw material of the rubber industry, rubber has good resilience, insulation, plasticity, wear resistance, oil resistance, acid and alkali resistance and other properties. It is widely used in tires, conveyor belts, hoses, soles, cables and other fields. However, rubber itself is a high-molecular flammable material. If it is exposed to high temperature or near a fire source for a long time, it is easy to produce thermal cracking reactions, releasing flammable rubber hydrocarbon gas, which will spontaneously ignite when it comes into contact with oxygen and reaches a certain concentration. Therefore, in these application environments, rubber is required to be flame-retardant and flame-resistant.

[0003] Chinese invention patent CN104927110A discloses a flame retardant rubber composition and its application. The flame retardant rubber composition includes the following raw materials: natural rubber, decabromodiphenylethane, antimony trioxide, red phosphorus and additives. The additives include one or more of reinforcing agents, antioxidants, lubricants, plasticizers, vulcanizers and vulcanization accelerators. The invention uses decabromodiphenylethane as the main flame retardant, and then combines antimony trioxide and red phosphorus with decabromodiphenylethane to greatly improve the flame retardant properties of the rubber composition, so that the rubber prepared is not easy to burn when close to a fire source and has the function of self-extinguishing when encountering an open flame. It can be widely used in the field of tires. However, the flame retardant used in the invention contains halogens, which will produce harmful substances during the combustion process, and a large amount of addition will also damage the performance of the rubber. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a flame retardant rubber composition, which effectively avoids the damage to the rubber properties caused by the addition of the flame retardant by adding a halogen-free rubber flame retardant that has good compatibility with the rubber matrix, and at the same time ensures that the rubber has good mechanical properties while improving the flame retardant properties of the rubber.

[0005] A flame retardant rubber composition comprises the following raw materials: butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant, antioxidant, sulfur, accelerator, white carbon black, cross-linking auxiliary agent and rubber flame retardant.

[0006] Preferably, a flame retardant rubber composition is composed of the following raw materials in parts by weight: 80-85 parts by weight of butadiene rubber, 15-20 parts by weight of methyl vinyl silicone rubber, 0.5-2 parts by weight of stearic acid, 2-4 parts by weight of zinc oxide, 2-5 parts by weight of antioxidant, 1-3 parts by weight of antioxidant, 1-2 parts by weight of sulfur, 1-2 parts by weight of accelerator, 10-15 parts by weight of white carbon black, 1-2 parts by weight of crosslinking aid, and 30-35 parts by weight of rubber flame retardant. The rubber flame retardant is prepared by mixing flame retardant I, flame retardant II and aluminum hydroxide and then ball milling.

[0007] Aluminum hydroxide is environmentally friendly and inexpensive. As an inorganic filler flame retardant, it has the effects of smoke elimination and flame retardancy. Its flame retardant mechanism includes dilution, cold trap and barrier effect, that is, aluminum hydroxide releases water vapor after high temperature heating to dilute the combustible gas, and the reaction is a strong endothermic process that can reduce the surface temperature of the combustible. The above flame retardant mechanism also determines that the flame retardant efficiency of aluminum hydroxide is relatively low, and a higher filling amount is often required, which has a greater damage to the rubber performance.

[0008] In order to improve the flame retardant efficiency of aluminum hydroxide and reduce the damage to rubber properties, the present invention adds an organic flame retardant component having excellent compatibility with the rubber matrix and mixes it with the rubber matrix.

[0009] Preferably, the preparation method of the flame retardant for rubber is:

[0010] (1) adding 5-6 parts by weight of melamine borate, 1-2 parts by weight of cobalt nitrate and 1-3 parts by weight of zinc nitrate to water for ultrasonic treatment, then heating and stirring, and after the reaction, concentrating under reduced pressure and drying to obtain a loaded metal polymer, adding 3-5 parts by weight of the loaded metal polymer to toluene and mixing evenly, and then adding 0.3-0.5 parts by weight of acrylic acid modified methylphenyl silicone resin, heating and stirring, reacting, and after the reaction, filtering and drying to obtain flame retardant I;

[0011] (2) under nitrogen atmosphere, 9-10 parts by weight of 3-(2-aminoethylamino)propylmethyldimethoxysilane was added to toluene and mixed evenly, then the mixture was cooled to low temperature, 8-12 parts by weight of triethylamine was added and stirred, and then 20-22 parts by weight of tetrapropyldiaminophosphonium chloride was added and stirred continuously, after which solid triethylamine hydrochloride was removed by suction filtration, and the filtrate was concentrated under reduced pressure and dried to obtain flame retardant II;

[0012] (3) Flame retardant I, flame retardant II and aluminum hydroxide are mixed in a mass ratio of 1-3:1-3:1 and then ball-milled to obtain the flame retardant for rubber.

[0013] The present invention firstly loads the organic component borate melamine containing flame retardant elements boron / nitrogen by transition metal cobalt and zinc. The transition metal cobalt ions and zinc ions can catalyze and accelerate the dehydration and crosslinking between the polymer chain and the flame retardant component, help form a more stable and dense carbon layer, and reduce the toxicity of the gas released by the combustion of the polymer, effectively overcoming the shortcomings of loose carbonization and low flame retardant efficiency when only a single component is used. Then, the acrylic acid-modified methylphenyl silicone resin is hydrophobically modified, which greatly improves the dispersibility and compatibility of the flame retardant component in the rubber matrix, which is not only beneficial to improving the flame retardant efficiency, but also can reduce the damage to the rubber performance.

[0014] Furthermore, the present invention uses tetrapropyl diaminophosphonium chloride to react with 3-(2-aminoethylamino)propylmethyldimethoxysilane to obtain a nitrogen / phosphorus / silicon ternary organic flame retardant component, which has excellent carbonization and stability. When heated at high temperature, a protective layer of silicon-carbon bond / silicon-oxygen bond structure can be formed on the surface of the rubber molecule, which plays an oxygen-isolating and heat-insulating role, further improving the flame retardant protection of the rubber. At the same time, this nitrogen / phosphorus / silicon ternary organic flame retardant component can generate silanol groups similar to the structure of methyl vinyl silicone rubber, one of the raw materials of the rubber composition, during the mixing process with the rubber matrix. There is a strong interaction between the two, which is very beneficial to improving the mechanical properties of the rubber.

[0015] Finally, the present invention achieves pre-dispersion of aluminum hydroxide in the organic flame retardant component by ball milling aluminum hydroxide and the two organic flame retardant components, thereby improving its dispersibility and compatibility with the rubber matrix and improving the mechanical properties of the rubber.

[0016] Preferably, the preparation method of the flame retardant for rubber is:

[0017] (1) adding 5-6 parts by weight of melamine borate, 1-2 parts by weight of cobalt nitrate and 1-3 parts by weight of zinc nitrate to 160-200 parts by weight of water, ultrasonicating for 20-40 minutes, then heating to 50-55° C. and stirring for 120-180 minutes, concentrating under reduced pressure and drying to obtain a loaded metal polymer, adding 3-5 parts by weight of the loaded metal polymer to 45-50 parts by weight of toluene and mixing evenly, then adding 0.3-0.5 parts by weight of acrylic acid modified methyl phenyl silicone resin, heating to 40-50° C. and stirring for 30-40 minutes, then heating to 75-80° C. and reacting for 160-180 minutes, then filtering and drying to obtain flame retardant I;

[0018] (2) Under a nitrogen atmosphere, 9-10 parts by weight of 3-(2-aminoethylamino)propylmethyldimethoxysilane is added to 150-180 parts by weight of toluene and mixed evenly, then the temperature is lowered to -35 to -40°C, 8-12 parts by weight of triethylamine is added, and stirring is continued for 10-15 minutes, and then 20-22 parts by weight of tetrapropyldiaminophosphonium chloride is added and stirring is continued for 40-45 minutes, and finally, the mixture is stirred at 20-25°C for 80-100 minutes, and after the mixture is stirred, solid triethylamine hydrochloride is removed by suction, and the filtrate is concentrated under reduced pressure and dried to obtain flame retardant II;

[0019] (3) Flame retardant I, flame retardant II and aluminum hydroxide are mixed in a mass ratio of 1-3:1-3:1 and ball milled for 100-150 minutes to obtain the flame retardant for rubber.

[0020] Preferably, in step (1), the ultrasonic power is 200-400 W and the ultrasonic frequency is 20-30 kHz.

[0021] Preferably, in step (3), the ball milling speed is 600-800 rpm, the ball-to-material ratio is 10-20:1, and the ball milling medium is 1-3 mm zirconia balls.

[0022] Preferably, the antioxidant is at least one of antioxidant RD, antioxidant BLE and antioxidant ODA.

[0023] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 2246.

[0024] Preferably, the accelerator is at least one of N-cyclohexyl-2-benzothiazolesulfenamide, dibenzothiazyl disulfide, and tetramethylthiuram disulfide.

[0025] Preferably, the crosslinking aid is at least one of trimethylolpropane trimethacrylate, triallyl isocyanurate, and 2,5-di-tert-butylperoxide-2,5-dimethylhexane.

[0026] The invention also provides a method for preparing the flame retardant rubber composition.

[0027] A method for preparing a flame retardant rubber composition comprises the following steps:

[0028] Add butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant, antioxidant, white carbon black and rubber flame retardant into an internal mixer, mix at 100-110° C. for 10-15 minutes, then add sulfur, accelerator and cross-linking aid and continue mixing for 10-20 minutes; then place in an open mixer, mix at 100-120° C. for 10-15 minutes, thin pass 2-5 times and then take out the sheet; finally place in a vulcanizer, vulcanize and shape at 160-170° C. to obtain the flame retardant rubber composition.

[0029] Beneficial effects of the present invention:

[0030] The flame retardant rubber composition prepared by the present invention has excellent flame retardant properties and mechanical properties. This is because the compatibility and dispersibility between the rubber flame retardant used in the present invention and the rubber matrix are very good, which improves the flame retardant efficiency and reduces the damage to the rubber performance. First, the rubber flame retardant of the present invention loads the organic component containing the flame retardant element boron / nitrogen through transition metals, and the cobalt ions and zinc ions can catalyze and accelerate the dehydration and crosslinking between the polymer chain and the flame retardant component, helping to form a more stable and dense carbon layer, and then improve the dispersibility and compatibility of the above flame retardant component in the rubber matrix through hydrophobic modification; secondly, the present invention prepares a nitrogen / phosphorus / silicon ternary organic flame retardant component with excellent carbonization and stability, and can form a protective layer of silicon-carbon bond / silicon-oxygen bond structure on the surface of the rubber molecule when heated at high temperature, which plays an oxygen-insulating and heat-insulating role, and further improves the flame retardant protection of the rubber. At the same time, it can generate silanols similar to the structure of methyl vinyl silicone rubber during the mixing process, and there is a strong interaction between the two, which is very beneficial to improving the mechanical properties of the rubber. DETAILED DESCRIPTION

[0031] The above content of the present invention is further described in detail below in conjunction with specific implementation modes, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments.

[0032] Methyl vinyl silicone rubber, brand: SR110-2, molecular weight: 450,000, Zhonghao Chenguang Chemical Research Institute Co., Ltd.

[0033] Butadiene rubber, brand: BR1220, high cis butadiene rubber, Japan Zeon Co., Ltd.

[0034] White carbon black, model: HB-139, fumed white carbon black, Hubei Huifu Nanomaterials Co., Ltd.

[0035] Acrylic acid modified methyl phenyl silicone resin, brand: SF100, Suzhou Senfeida Chemical Co., Ltd.

[0036] Example 1

[0037] A flame retardant rubber composition is composed of the following raw materials in parts by weight: 82 parts by weight of butadiene rubber, 18 parts by weight of methyl vinyl silicone rubber, 1 part by weight of stearic acid, 3.5 parts by weight of zinc oxide, 3 parts by weight of antioxidant RD, 2 parts by weight of antioxidant 1076, 1.5 parts by weight of sulfur, 1.5 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide, 12 parts by weight of white carbon black, 1.5 parts by weight of trimethylolpropane trimethacrylate, and 32 parts by weight of a rubber flame retardant.

[0038] The preparation method of the rubber flame retardant is:

[0039] (1) 5.5 parts by weight of melamine borate, 1.5 parts by weight of cobalt nitrate and 2 parts by weight of zinc nitrate were added to 180 parts by weight of water and ultrasonicated for 30 minutes, then heated to 53° C. and stirred for 150 minutes, and then concentrated under reduced pressure and dried to obtain a loaded metal polymer, 4 parts by weight of the loaded metal polymer were added to 46 parts by weight of toluene and mixed evenly, and then 0.35 parts by weight of acrylic acid-modified methylphenyl silicone resin was added, heated to 45° C. and stirred for 35 minutes, and then heated to 78° C. to react for 165 minutes, and then filtered and dried to obtain flame retardant I; wherein the ultrasonic power is 300 W and the ultrasonic frequency is 25 kHz;

[0040] (2) Under a nitrogen atmosphere, 9.5 parts by weight of 3-(2-aminoethylamino)propylmethyldimethoxysilane was added to 160 parts by weight of toluene and mixed evenly, then the temperature was lowered to -38°C, 10 parts by weight of triethylamine was added, and the mixture was stirred for 12 minutes, and then 21.5 parts by weight of tetrapropyldiaminophosphonium chloride was added and the mixture was stirred for 43 minutes, and finally the mixture was stirred at 23°C for 90 minutes. After the mixture was stirred, the solid triethylamine hydrochloride was removed by suction, and the filtrate was concentrated under reduced pressure and dried to obtain flame retardant II;

[0041] (3) Flame retardant I, flame retardant II and aluminum hydroxide were mixed in a mass ratio of 2:2:1 and ball milled for 120 minutes to obtain the flame retardant for rubber, wherein the ball milling speed was 700 rpm, the ball-to-material ratio was 15:1, and the ball milling medium was 2 mm zirconium oxide balls.

[0042] A method for preparing a flame retardant rubber composition comprises the following steps:

[0043] Butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant RD, antioxidant 1076, white carbon black and flame retardant for rubber are added into an internal mixer, mixed at 105° C. for 12 minutes, and then sulfur, N-cyclohexyl-2-benzothiazolesulfenamide and trimethylolpropane trimethacrylate are added and mixed for 15 minutes; then the mixture is placed in an open mixer, mixed at 110° C. for 12 minutes, and the mixture is thinned three times before being unrolled; finally, the mixture is placed in a vulcanizer, and vulcanized and formed at 165° C. to obtain the flame retardant rubber composition.

[0044] Example 2

[0045] A flame retardant rubber composition is composed of the following raw materials in parts by weight: 82 parts by weight of butadiene rubber, 18 parts by weight of methyl vinyl silicone rubber, 1 part by weight of stearic acid, 3.5 parts by weight of zinc oxide, 3 parts by weight of antioxidant RD, 2 parts by weight of antioxidant 1076, 1.5 parts by weight of sulfur, 1.5 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide, 12 parts by weight of white carbon black, 1.5 parts by weight of trimethylolpropane trimethacrylate, and 32 parts by weight of a rubber flame retardant.

[0046] The preparation method of the rubber flame retardant is:

[0047] (1) 5.5 parts by weight of melamine borate, 1.5 parts by weight of cobalt nitrate and 2 parts by weight of zinc nitrate were added to 180 parts by weight of water and ultrasonicated for 30 minutes, then heated to 53° C. and stirred for 150 minutes, and then concentrated under reduced pressure and dried to obtain a loaded metal polymer, 4 parts by weight of the loaded metal polymer were added to 46 parts by weight of toluene and mixed evenly, and then 0.35 parts by weight of acrylic acid-modified methylphenyl silicone resin was added, heated to 45° C. and stirred for 35 minutes, and then heated to 78° C. to react for 165 minutes, and then filtered and dried to obtain flame retardant I; wherein the ultrasonic power is 300 W and the ultrasonic frequency is 25 kHz;

[0048] (2) The flame retardant I and aluminum hydroxide were mixed in a mass ratio of 4:1 and ball-milled for 120 minutes to obtain the flame retardant for rubber, wherein the ball-milling speed was 700 rpm, the ball-to-material ratio was 15:1, and the ball-milling medium was 2 mm zirconium oxide balls.

[0049] A method for preparing a flame retardant rubber composition comprises the following steps:

[0050] Butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant RD, antioxidant 1076, white carbon black and flame retardant for rubber are added into an internal mixer, mixed at 105° C. for 12 minutes, and then sulfur, N-cyclohexyl-2-benzothiazolesulfenamide and trimethylolpropane trimethacrylate are added and mixed for 15 minutes; then the mixture is placed in an open mixer, mixed at 110° C. for 12 minutes, and the mixture is thinned three times before being unrolled; finally, the mixture is placed in a vulcanizer, and vulcanized and formed at 165° C. to obtain the flame retardant rubber composition.

[0051] Example 3

[0052] A flame retardant rubber composition is composed of the following raw materials in parts by weight: 82 parts by weight of butadiene rubber, 18 parts by weight of methyl vinyl silicone rubber, 1 part by weight of stearic acid, 3.5 parts by weight of zinc oxide, 3 parts by weight of antioxidant RD, 2 parts by weight of antioxidant 1076, 1.5 parts by weight of sulfur, 1.5 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide, 12 parts by weight of white carbon black, 1.5 parts by weight of trimethylolpropane trimethacrylate, and 32 parts by weight of a rubber flame retardant.

[0053] The preparation method of the rubber flame retardant is:

[0054] (1) adding 5.5 parts by weight of melamine borate, 1.5 parts by weight of cobalt nitrate and 2 parts by weight of zinc nitrate to 180 parts by weight of water, ultrasonicating for 30 minutes, then heating to 53° C. and stirring for 150 minutes, and then concentrating under reduced pressure and drying to obtain flame retardant I; wherein the ultrasonic power is 300 W and the ultrasonic frequency is 25 kHz;

[0055] (2) Under a nitrogen atmosphere, 9.5 parts by weight of 3-(2-aminoethylamino)propylmethyldimethoxysilane was added to 160 parts by weight of toluene and mixed evenly, then the temperature was lowered to -38°C, 10 parts by weight of triethylamine was added, and the mixture was stirred for 12 minutes, and then 21.5 parts by weight of tetrapropyldiaminophosphonium chloride was added and the mixture was stirred for 43 minutes, and finally the mixture was stirred at 23°C for 90 minutes. After the mixture was stirred, the solid triethylamine hydrochloride was removed by suction, and the filtrate was concentrated under reduced pressure and dried to obtain flame retardant II;

[0056] (3) Flame retardant I, flame retardant II and aluminum hydroxide were mixed in a mass ratio of 2:2:1 and ball milled for 120 minutes to obtain the flame retardant for rubber, wherein the ball milling speed was 700 rpm, the ball-to-material ratio was 15:1, and the ball milling medium was 2 mm zirconium oxide balls.

[0057] A method for preparing a flame retardant rubber composition comprises the following steps:

[0058] Butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant RD, antioxidant 1076, white carbon black and flame retardant for rubber are added into an internal mixer, mixed at 105° C. for 12 minutes, and then sulfur, N-cyclohexyl-2-benzothiazolesulfenamide and trimethylolpropane trimethacrylate are added and mixed for 15 minutes; then the mixture is placed in an open mixer, mixed at 110° C. for 12 minutes, and the mixture is thinned three times before being unrolled; finally, the mixture is placed in a vulcanizer, and vulcanized and formed at 165° C. to obtain the flame retardant rubber composition.

[0059] Example 4

[0060] A flame retardant rubber composition is composed of the following raw materials in parts by weight: 82 parts by weight of butadiene rubber, 18 parts by weight of methyl vinyl silicone rubber, 1 part by weight of stearic acid, 3.5 parts by weight of zinc oxide, 3 parts by weight of antioxidant RD, 2 parts by weight of antioxidant 1076, 1.5 parts by weight of sulfur, 1.5 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide, 12 parts by weight of white carbon black, 1.5 parts by weight of trimethylolpropane trimethacrylate, and 32 parts by weight of a rubber flame retardant.

[0061] The preparation method of the rubber flame retardant is:

[0062] (1) 4 parts by weight of boric acid melamine were added to 46 parts by weight of toluene and mixed evenly, and then 0.35 parts by weight of acrylic acid modified methyl phenyl silicone resin was added, heated to 45° C. and stirred for 35 minutes, and then heated to 78° C. and reacted for 165 minutes. After the reaction, the mixture was filtered and dried to obtain flame retardant I; wherein the ultrasonic power was 300 W and the ultrasonic frequency was 25 kHz;

[0063] (2) Under a nitrogen atmosphere, 9.5 parts by weight of 3-(2-aminoethylamino)propylmethyldimethoxysilane was added to 160 parts by weight of toluene and mixed evenly, then the temperature was lowered to -38°C, 10 parts by weight of triethylamine was added, and the mixture was stirred for 12 minutes, and then 21.5 parts by weight of tetrapropyldiaminophosphonium chloride was added and the mixture was stirred for 43 minutes, and finally the mixture was stirred at 23°C for 90 minutes. After the mixture was stirred, the solid triethylamine hydrochloride was removed by suction, and the filtrate was concentrated under reduced pressure and dried to obtain flame retardant II;

[0064] (3) Flame retardant I, flame retardant II and aluminum hydroxide were mixed in a mass ratio of 2:2:1 and ball milled for 120 minutes to obtain the flame retardant for rubber, wherein the ball milling speed was 700 rpm, the ball-to-material ratio was 15:1, and the ball milling medium was 2 mm zirconium oxide balls.

[0065] A method for preparing a flame retardant rubber composition comprises the following steps:

[0066] Butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant RD, antioxidant 1076, white carbon black and flame retardant for rubber are added into an internal mixer, mixed at 105° C. for 12 minutes, and then sulfur, N-cyclohexyl-2-benzothiazolesulfenamide and trimethylolpropane trimethacrylate are added and mixed for 15 minutes; then the mixture is placed in an open mixer, mixed at 110° C. for 12 minutes, and the mixture is thinned three times before being unrolled; finally, the mixture is placed in a vulcanizer, and vulcanized and formed at 165° C. to obtain the flame retardant rubber composition.

[0067] Example 5

[0068] A flame retardant rubber composition is composed of the following raw materials in parts by weight: 82 parts by weight of butadiene rubber, 18 parts by weight of methyl vinyl silicone rubber, 1 part by weight of stearic acid, 3.5 parts by weight of zinc oxide, 3 parts by weight of antioxidant RD, 2 parts by weight of antioxidant 1076, 1.5 parts by weight of sulfur, 1.5 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide, 12 parts by weight of white carbon black, 1.5 parts by weight of trimethylolpropane trimethacrylate, and 32 parts by weight of a rubber flame retardant.

[0069] The preparation method of the rubber flame retardant is:

[0070] (1) Under a nitrogen atmosphere, 9.5 parts by weight of 3-(2-aminoethylamino)propylmethyldimethoxysilane was added to 160 parts by weight of toluene and mixed evenly, then the temperature was lowered to -38°C, 10 parts by weight of triethylamine was added, and the mixture was stirred for 12 minutes, and then 21.5 parts by weight of tetrapropyldiaminophosphonium chloride was added and the mixture was stirred for 43 minutes, and finally the mixture was stirred at 23°C for 90 minutes. After the mixture was stirred, solid triethylamine hydrochloride was removed by suction, and the filtrate was concentrated under reduced pressure and dried to obtain flame retardant II;

[0071] (2) Flame retardant II and aluminum hydroxide were mixed in a mass ratio of 4:1 and ball-milled for 120 minutes to obtain the flame retardant for rubber, wherein the ball-milling speed was 700 rpm, the ball-to-material ratio was 15:1, and the ball-milling medium was 2 mm zirconium oxide balls.

[0072] A method for preparing a flame retardant rubber composition comprises the following steps:

[0073] Butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant RD, antioxidant 1076, white carbon black and flame retardant for rubber are added into an internal mixer, mixed at 105° C. for 12 minutes, and then sulfur, N-cyclohexyl-2-benzothiazolesulfenamide and trimethylolpropane trimethacrylate are added and mixed for 15 minutes; then the mixture is placed in an open mixer, mixed at 110° C. for 12 minutes, and the mixture is thinned three times before being unrolled; finally, the mixture is placed in a vulcanizer, and vulcanized and formed at 165° C. to obtain the flame retardant rubber composition.

[0074] Test Example 1

[0075] Mechanical properties: The flame retardant rubber composition prepared in the above embodiment was tested according to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". Sample: 1A type, length 20 mm. Each embodiment was tested in 7 parallel groups, and the average value was calculated.

[0076] Table 1 Tensile strength of flame retardant rubber composition

[0077] Tensile strength, MPa Example 1 10.35 Example 2 8.07 Example 3 9.20

[0078] Test Example 2

[0079] Flame retardant properties: The flame retardant rubber composition prepared in the above examples was tested according to GB / T 10707-2008 "Determination of Rubber Combustion Properties". Method A oxygen index method was used, and the sample was 150 mm long, 6.5 mm wide, and 3 mm thick. Seven groups were tested in parallel for each example, and the average value was calculated.

[0080] Table 2 Oxygen index of flame retardant rubber composition

[0081] Oxygen index, % Example 1 33.5 Example 2 28.3 Example 3 32.0 Example 4 30.7 Example 5 29.6

[0082] By comparing the above embodiments, it can be seen that the flame retardant rubber composition of Example 1 has the best flame retardant properties and mechanical properties. The reason may be that the flame retardant for rubber used in Example 1, on the one hand, loads the organic component containing the flame retardant elements boron / nitrogen through transition metals, and the cobalt ions and zinc ions can catalyze and accelerate the dehydration and crosslinking between the polymer chain and the flame retardant component, helping to form a more stable and dense carbon layer, effectively overcoming the shortcomings of using only a single component for loose carbonization and low flame retardant efficiency, and then improving the dispersion and compatibility of the above flame retardant component in the rubber matrix through hydrophobic modification; on the other hand, the nitrogen / phosphorus / silicon ternary organic flame retardant component contained therein has excellent carbonization and mechanical properties. Stability, when heated at high temperature, a protective layer of silicon-carbon bond / silicon-oxygen bond structure can be formed on the surface of rubber molecules, which plays an oxygen-isolating and heat-insulating role, further improving the flame-retardant protection of rubber. At the same time, this nitrogen / phosphorus / silicon ternary organic flame-retardant component can generate silanol groups similar to the structure of methyl vinyl silicone rubber during the mixing process with the rubber matrix. There is a strong interaction between the two, which is very beneficial to improving the mechanical properties of rubber. In addition, the rubber flame retardant used in Example 1 is achieved by ball-milling aluminum hydroxide and the above-mentioned two organic flame-retardant components to achieve pre-dispersion of aluminum hydroxide in the organic flame-retardant component, thereby improving its dispersibility and compatibility with the rubber matrix and improving the mechanical properties of the rubber.

[0083] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A flame retardant rubber composition, characterized in that: The invention comprises the following raw materials: 80-85 parts by weight of butadiene rubber, 15-20 parts by weight of methyl vinyl silicone rubber, 0.5-2 parts by weight of stearic acid, 2-4 parts by weight of zinc oxide, 2-5 parts by weight of antioxidant, 1-3 parts by weight of antioxidant, 1-2 parts by weight of sulfur, 1-2 parts by weight of accelerator, 10-15 parts by weight of white carbon black, 1-2 parts by weight of crosslinking aid, and 30-35 parts by weight of flame retardant for rubber; The preparation method of the rubber flame retardant is: (1) adding melamine borate, cobalt nitrate and zinc nitrate to water for ultrasonic treatment, then heating and stirring, concentrating and drying to obtain metal-loaded melamine borate, adding the metal-loaded melamine borate to toluene and mixing evenly, then adding acrylic acid-modified methylphenyl silicone resin, heating and stirring, reacting, filtering and drying to obtain flame retardant I; (2) Add 3-(2-aminoethylamino)propylmethyldimethoxysilane to toluene under nitrogen atmosphere and mix well, then cool to low temperature and add triethylamine and stir, then add tetrapropyldiaminophosphonium chloride and continue stirring, filter with suction, concentrate and dry the filtrate to obtain flame retardant II; (3) Flame retardant I, flame retardant II and aluminum hydroxide are mixed and ball-milled to obtain the flame retardant for rubber; the mass ratio of flame retardant I, flame retardant II and aluminum hydroxide is 1-3:1-3:

1.

2. The flame retardant rubber composition according to claim 1, characterized in that: The antioxidant is at least one of antioxidant RD, antioxidant BLE and antioxidant ODA.

3. The flame retardant rubber composition according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 2246.

4. The flame retardant rubber composition according to claim 1, characterized in that: The accelerator is at least one of N-cyclohexyl-2-benzothiazole sulfenamide, dibenzothiazyl disulfide, and tetramethylthiuram disulfide.

5. The flame retardant rubber composition according to claim 1, characterized in that: The crosslinking aid is at least one of trimethylolpropane trimethacrylate, triallyl isocyanurate, and 2,5-di-tert-butylperoxide-2,5-dimethylhexane.

6. The method for preparing the flame retardant rubber composition according to any one of claims 1 to 5, characterized in that: The following steps are involved: Butadiene rubber, methyl vinyl silicone rubber, stearic acid, zinc oxide, antioxidant, antioxidant, white carbon black and flame retardant for rubber are added to an internal mixer for mixing, and then sulfur, accelerator and cross-linking aid are added for further mixing; then the mixture is mixed in an open mixer and thinly sheeted; finally, the mixture is vulcanized and formed in a vulcanizer to obtain the flame retardant rubber composition.