Low-smoke flame-retardant rubber and preparation method thereof

Abstract

The invention relates to the technical field of rubber, and discloses low-smoke flame-retardant rubber and a preparation method thereof. The smoke-suppressing flame-retardant rubber comprises the following raw materials in parts by weight: 40-60 parts of nitrile rubber, 20-30 parts of ethylene propylene diene monomer, 15-25 parts of natural rubber, 5-15 parts of polystyrene, 10-20 parts of a modified flame retardant, 10-16 parts of a reinforcing filler, 2-4 parts of a silane coupling agent, 5-7 parts of sulfur, 0.5-2 parts of a vulcanization accelerator and 0.2-1 part of an antioxidant. According to the invention, a plurality of rubbers are used as base materials, and the flame retardant, the reinforcing filler and other assistants are added, so that the rubber material has excellent smoke suppression and flame retardant properties, and also has excellent mechanical properties; wherein through the synergistic effect between the modified flame retardant and the reinforcing filler, the flame retardance and smoke suppression performance of the rubber are improved.

Description

Technical Field

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

[0002] Rubber materials are usually composed of basic rubber (such as natural rubber, nitrile rubber, EPDM rubber, etc.), vulcanizers and vulcanization accelerators, flame retardants, antioxidants, dispersants and other functional additives. Rubber materials are widely used in wires and cables, building sealing materials, vehicle interiors, electronic equipment housings, etc. However, rubber materials themselves do not have flame retardant and smoke suppression properties. Therefore, the material needs to be processed to have certain flame retardant and smoke suppression properties to meet actual application needs.

[0003] Rubber materials usually use flame retardants and smoke suppressants to achieve flame retardant and smoke suppression properties, but these additives are prone to precipitation and migration in rubber materials, which reduces the flame retardant and smoke suppression properties of rubber materials. In addition, a large amount of flame retardants and smoke suppressants need to be added to achieve better flame retardant and smoke suppression properties, and the addition of a large amount of additives will cause a decrease in the overall performance of the material. Therefore, researchers need to develop a low-smoke, flame-retardant rubber material to meet practical application needs. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a low-smoke flame-retardant rubber and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A low-smoke flame-retardant rubber, comprising the following raw materials in parts by weight: 40-60 parts of nitrile rubber, 20-30 parts of EPDM rubber, 15-25 parts of natural rubber, 5-15 parts of polystyrene, 10-20 parts of modified flame retardant, 10-16 parts of reinforcing filler, 2-4 parts of silane coupling agent, 5-7 parts of sulfur, 0.5-2 parts of vulcanization accelerator, and 0.2-1 parts of antioxidant; The modified flame retardant is prepared by the following steps: Step A1, (3-aminopropyl)trimethoxysilane and triethylamine are added to dichloromethane and mixed evenly, and then dimethyl chlorophosphate is added dropwise in an ice-water bath, and stirring is continued for 40-60 minutes, the system temperature is raised to room temperature, stirring is continued for 8-12 hours, and then filtered, washed, and vacuum dried to obtain phosphoric acid ester silane; Step A2, adding methyltrimethoxysilane and phosphoric acid ester silane to the ethanol solution, stirring at a speed of 400-600 rpm for 2-3 hours, then adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane and allyltrimethoxysilane, continuing to stir for 1-2 hours, then adding ammonia water and stopping stirring, transferring to a 60° C. water bath and standing for 30-60 minutes, centrifuging, washing, and drying to obtain functionalized organosilicon microspheres; Step A3, dispersing 4-aminophthalic acid in ethanol, recorded as solution 1; adding functionalized organosilicon microspheres to ethanol and dispersing them evenly, then adding solution 1, and heating to 50-60° C., reacting for 5-7 hours, filtering, washing, and drying to obtain modified organosilicon microspheres; Step A4, adding (CH3COO)2Ni·4H2O to ethanol and dispersing it uniformly, recorded as solution 2; dispersing the modified silicone microspheres in ethanol, and then adding solution 2 dropwise, adjusting the pH to 6-8, and then raising the temperature to 60-80°C, reacting for 2-3h, filtering, washing, and vacuum drying to obtain a modified flame retardant; Further, in step A1, the usage ratio of (3-aminopropyl)trimethoxysilane, triethylamine, dichloromethane and dimethyl chlorophosphate is 0.1-0.3 mol: 0.1-0.3 mol: 500 mL: 0.1-0.3 mol; Further, in step A2, the amount ratio of methyltrimethoxysilane, phosphoric acid ester silane, ethanol solution, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and allyltrimethoxysilane is 0.1-0.5 mol: 0.05-0.1 mol: 200 mL: 0.01-0.03 mol: 0.005-0.01 mol, and the volume ratio of ethanol to deionized water in the ethanol solution is 1:1; Further, in step A3, the amount ratio of the functionalized organosilicon microspheres, ethanol and solution 1 is 1 g: 50 mL: 20 mL; Further, the dosage ratio of 4-aminophthalic acid and ethanol in solution 1 of step A3 is 0.1-0.5 g: 20 mL; Furthermore, in step A4, the usage ratio of the modified organosilicon microspheres, ethanol and solution 2 is 1 g:100 mL:100 mL, and the usage ratio of (CH3COO)2Ni·4H2O and ethanol in solution 2 is 0.05-0.3 g:100 mL.

[0006] The reinforcing filler is prepared by the following steps: Step B1, adding allyltrimethoxysilane to a mixture of deionized water and ethanol, recorded as solution 3; adding calcium carbonate to isopropanol and dispersing it evenly, then adding solution 3, and reacting at 70-90° C. for 3-5 hours, centrifuging, washing, and drying to obtain functionalized calcium carbonate; Step B2, adding functionalized calcium carbonate to a mixture of isopropanol and deionized water, and heating to 60-70°C, then adding acrylic acid and ammonium persulfate, raising the system temperature to 85-95°C, continuing the reaction for 1-2h, filtering and drying, and obtaining PAA@calcium carbonate material; Step B3, adding the PAA@calcium carbonate material to an 8-12wt% aluminum chloride solution and ultrasonically treating it for 10 minutes, then dropping a saturated ammonia solution, and reacting it at 40-50°C and 3.5-3.8MPa for 2-3 hours, and then reacting it at 10-15°C and vacuum conditions for 1-2 hours, filtering, and drying to obtain a reinforcing filler; Further, in step B1, the amount ratio of calcium carbonate, isopropanol and solution 3 is 1-3 g: 50 mL: 50 mL, and the volume ratio of allyltrimethoxysilane, deionized water and ethanol in solution 3 is 0.5-1.5: 3.5-4.5: 45; Further, in step B2, the usage ratio of functionalized calcium carbonate, isopropanol, deionized water, acrylic acid and ammonium persulfate is 1-3 g: 80 mL: 20 mL: 0.005-0.02 mol: 0.003-0.012 g; Furthermore, in step B3, the dosage ratio of PAA@calcium carbonate material, aluminum chloride solution and saturated ammonia solution is 1-3 g: 10-20 mL: 20-40 mL.

[0007] A method for preparing low-smoke flame-retardant rubber comprises the following steps: Step S1, weighing raw materials by weight, adding nitrile rubber, EPDM rubber, natural rubber and polystyrene into an internal mixer, and mixing at 60-70° C. for 8-12 minutes to obtain a mixed rubber material; Step S2, adding the mixed rubber material, modified flame retardant, reinforcing filler and antioxidant into an open mill, mixing at 90-120° C. for 5-10 min, then adding sulfur, vulcanization accelerator and silane coupling agent, continuing to mix at 40-60° C. for 1-3 min, thinning 6-8 times, and discharging to obtain a sheet; Step S3, vulcanizing and molding the sheet on a flat vulcanizer to obtain the smoke-suppressing and flame-retardant rubber.

[0008] Beneficial effects of the present invention: The smoke-suppressing and flame-retardant rubber in the present application is based on a variety of rubbers, and is added with flame retardants, reinforcing fillers and other additives, so that the rubber material has excellent smoke suppression and flame retardant properties, and also has excellent mechanical properties; among them, the modified flame retardant and reinforcing filler have a synergistic effect, thereby improving the flame retardant and smoke suppression properties of the rubber.

[0009] In the modified flame retardant, the -NH2 in (3-aminopropyl)trimethoxysilane and the -Cl group in dimethyl chlorophosphate are first reacted to generate phosphate-containing silane; then methyltrimethoxysilane, phosphate-containing silane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and allyltrimethoxysilane are used as raw materials to synthesize functionalized silicone microspheres; then the epoxy groups on the surface of the functionalized silicone microspheres are reacted with the amino groups in 2-aminoterephthalic acid to synthesize modified silicone microspheres; finally, the 4-aminophthalic acid in the modified silicone microspheres is coordinated with nickel ions to synthesize modified flame retardants containing metal ions. The introduction of modified flame retardants can improve the flame retardancy and smoke suppression of rubber. This is because C, Si, N, P and transition metal ions (Ni 2+ ) and other flame retardant elements. Through the synergistic effect of each element, the matrix can produce a dense and continuous carbon layer when it burns, and the carbon layer has a physical barrier effect, which can isolate the heat and mass transfer during combustion; among them, the transition metal ions and P elements work synergistically to play a role in catalyzing carbonization, thereby inhibiting the release of smoke when the matrix burns; the N element exists in the form of non-combustible gases such as NH3, and plays a flame retardant role in the gas phase; the Si element generates SiO2 during combustion, and SiO2 can participate in the formation of the carbon layer during combustion and improve the density of the carbon layer. In addition, carbon-carbon double bonds are introduced into the modified flame retardant, and the carbon-carbon double bonds can participate in the vulcanization of the matrix, avoiding the degradation of flame retardant and smoke suppression performance caused by the migration and precipitation of traditional flame retardants in the matrix.

[0010] In the reinforcing filler, the surface of calcium carbonate is first modified by silane coupling agent, double bonds are introduced on the surface of calcium carbonate, and functionalized calcium carbonate is synthesized; under the action of initiator ammonium persulfate, the copolymerization reaction between the double bonds on the surface of functionalized calcium carbonate and acrylic acid is used to synthesize PAA@calcium carbonate material; finally, aluminum hydroxide is generated by aluminum chloride and ammonia water, and the reinforcing filler is synthesized by the adsorption of polyacrylic acid on aluminum hydroxide. The reinforcing filler acts as a filler in the rubber matrix, which can reduce production costs and improve the comprehensive performance of rubber as well as flame retardant and smoke suppression performance; this is because the reinforcing filler is based on calcium carbonate, and calcium carbonate has poor dispersibility in the matrix and is easy to agglomerate, thereby reducing the comprehensive performance of the rubber material. After modifying its surface, the dispersibility is improved, and the double bond structure contained in the modified surface is used to coat polyacrylic acid, which further improves the dispersibility of the dispersed calcium carbonate. At the same time, polyacrylic acid also has excellent adsorption and can effectively adsorb the aluminum hydroxide particles generated subsequently, and aluminum hydroxide can play a certain flame retardant and smoke suppression role in the rubber matrix, and synergizes with the modified flame retardant to improve the flame retardancy of the rubber material. DETAILED DESCRIPTION

[0011] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0012] The modified flame retardant is prepared by the following steps: Step A1, add 0.1 mol (3-aminopropyl) trimethoxysilane and 0.1 mol triethylamine into 500 mL dichloromethane and mix well, then add 0.1 mol dimethyl chlorophosphate dropwise in an ice-water bath, and continue stirring for 40 min, raise the system temperature to room temperature and continue stirring for 8 h, filter, wash, and vacuum dry to obtain phosphate-containing silane; Step A2, adding 0.1 mol of methyltrimethoxysilane and 0.05 mol of phosphoric acid ester silane to 200 mL of ethanol solution, and stirring at 400 rpm for 2 hours, then adding 0.01 mol of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.005 mol of allyltrimethoxysilane and continuing stirring for 1 hour, then adding ammonia water and stopping stirring, and transferring to a 60° C. water bath and standing for 30 minutes, centrifuging, washing, and drying to obtain functionalized organosilicon microspheres, wherein the volume ratio of ethanol to deionized water in the ethanol solution is 1:1; Step A3, dispersing 0.1 g of 4-aminophthalic acid in 20 mL of ethanol, recorded as solution 1; adding 1 g of functionalized organosilicon microspheres to 50 mL of ethanol and dispersing them evenly, then adding 20 mL of solution 1, heating to 50° C., reacting for 5 h, filtering, washing, and drying to obtain modified organosilicon microspheres; Step A4, add 0.05g (CH3COO)2Ni·4H2O into 100mL ethanol and disperse evenly, record as solution 2; disperse 1g modified silicone microspheres in 100mL ethanol, then add 100mL solution 2 dropwise, adjust the pH to 6, then increase the temperature to 60°C, react for 2h, filter, wash, and vacuum dry to obtain the modified flame retardant.

[0013] The reinforcing filler is prepared by the following steps: Step B1, adding allyltrimethoxysilane to a mixture of deionized water and ethanol, recorded as solution 3; adding 1g of calcium carbonate to 50mL of isopropanol and dispersing evenly, then adding 50mL of solution 3, and reacting at 70°C for 3h, centrifuging, washing, and drying to obtain functionalized calcium carbonate, wherein the volume ratio of allyltrimethoxysilane, deionized water, and ethanol in solution 3 is 0.5:4.5:45; Step B2, add 1 g of functionalized calcium carbonate to a mixture of 80 mL of isopropanol and 20 mL of deionized water, and heat to 60°C, then add 0.005 mol of acrylic acid and 0.003 g of ammonium persulfate, raise the system temperature to 85°C, continue the reaction for 1 h, filter and dry to obtain PAA@calcium carbonate material; Step B3, add 1g of PAA@calcium carbonate material to 10mL of 12wt% aluminum chloride solution and ultrasonically treat for 10min, then add 20mL of saturated ammonia solution, and react at 40°C and 3.5MPa for 2h, then react at 10°C and vacuum conditions for 1h, filter and dry to obtain a reinforced filler. Example

[0014] The modified flame retardant is prepared by the following steps: Step A1, add 0.2 mol (3-aminopropyl) trimethoxysilane and 0.2 mol triethylamine into 500 mL dichloromethane and mix well, then add 0.2 mol dimethyl chlorophosphate dropwise in an ice-water bath, and continue stirring for 50 min, raise the system temperature to room temperature and continue stirring for 10 h, filter, wash, and vacuum dry to obtain phosphate-containing silane; Step A2, add 0.3 mol of methyltrimethoxysilane and 0.075 mol of phosphoric acid ester silane to 200 mL of ethanol solution, and stir at a speed of 500 rpm for 2.5 hours, then add 0.02 mol of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.0075 mol of allyltrimethoxysilane and continue stirring for 1.5 hours, then add ammonia water and stop stirring, transfer to a 60°C water bath and stand for 45 minutes, centrifuge, wash, and dry to obtain functionalized organosilicon microspheres, and the volume ratio of ethanol to deionized water in the ethanol solution is 1:1; Step A3, dispersing 0.3 g of 4-aminophthalic acid in 20 mL of ethanol, recorded as solution 1; adding 1 g of functionalized organosilicon microspheres to 50 mL of ethanol and dispersing them evenly, then adding 20 mL of solution 1, heating to 55° C., reacting for 6 h, filtering, washing, and drying to obtain modified organosilicon microspheres; Step A4, add 0.1g (CH3COO)2Ni·4H2O into 100mL ethanol and disperse it evenly, which is recorded as solution 2; disperse 1g modified silicone microspheres in 100mL ethanol, and then add 100mL solution 2 dropwise, adjust the pH to 7, and then increase the temperature to 70°C, react for 2.5h, filter, wash, and vacuum dry to obtain a modified flame retardant.

[0015] The reinforcing filler is prepared by the following steps: Step B1, adding allyltrimethoxysilane to a mixture of deionized water and ethanol, recorded as solution 3; adding 2 g of calcium carbonate to 50 mL of isopropanol and dispersing evenly, then adding 50 mL of solution 3, and reacting at 80° C. for 4 h, centrifuging, washing, and drying to obtain functionalized calcium carbonate, wherein the volume ratio of allyltrimethoxysilane, deionized water, and ethanol in solution 3 is 1:4:45; Step B2, add 2 g of functionalized calcium carbonate to a mixture of 80 mL of isopropanol and 20 mL of deionized water, and heat to 65°C, then add 0.1 mol of acrylic acid and 0.007 g of ammonium persulfate, raise the system temperature to 90°C, continue the reaction for 1.5 h, filter and dry to obtain PAA@calcium carbonate material; Step B3, add 2g of PAA@calcium carbonate material to 15mL of 10wt% aluminum chloride solution and ultrasonically treat for 10min, then add 30mL of saturated ammonia solution, and react at 45°C and 3.8MPa for 2.5h, then react at 15°C and vacuum conditions for 1.5h, filter and dry to obtain a reinforced filler. Example

[0016] The modified flame retardant is prepared by the following steps: Step A1, add 0.3 mol (3-aminopropyl) trimethoxysilane and 0.3 mol triethylamine into 500 mL dichloromethane and mix well, then add 0.3 mol dimethyl chlorophosphate dropwise in an ice-water bath, and continue stirring for 60 min, raise the system temperature to room temperature and continue stirring for 12 h, filter, wash, and vacuum dry to obtain phosphate-containing silane; Step A2, adding 0.5 mol of methyltrimethoxysilane and 0.1 mol of phosphoric acid ester silane to 200 mL of ethanol solution, and stirring at a speed of 600 rpm for 3 hours, then adding 0.03 mol of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and 0.01 mol of allyltrimethoxysilane and continuing stirring for 2 hours, then adding ammonia water and stopping stirring, and transferring to a 60° C. water bath and standing for 60 minutes, centrifuging, washing, and drying to obtain functionalized organosilicon microspheres, wherein the volume ratio of ethanol to deionized water in the ethanol solution is 1:1; Step A3, dispersing 0.5 g of 4-aminophthalic acid in 20 mL of ethanol, recorded as solution 1; adding 1 g of functionalized organosilicon microspheres to 50 mL of ethanol and dispersing them evenly, then adding 20 mL of solution 1, heating to 60° C., reacting for 7 h, filtering, washing, and drying to obtain modified organosilicon microspheres; Step A4, add 0.3g (CH3COO)2Ni·4H2O into 100mL ethanol and disperse it evenly, which is recorded as solution 2; disperse 1g modified silicone microspheres in 100mL ethanol, and then add 100mL solution 2 dropwise, adjust the pH to 8, then increase the temperature to 80°C, react for 3h, filter, wash, and vacuum dry to obtain a modified flame retardant.

[0017] The reinforcing filler is prepared by the following steps: Step B1, adding allyltrimethoxysilane to a mixture of deionized water and ethanol, recorded as solution 3; adding 3g of calcium carbonate to 50mL of isopropanol and dispersing evenly, then adding 50mL of solution 3, and reacting at 90°C for 5h, centrifuging, washing, and drying to obtain functionalized calcium carbonate, wherein the volume ratio of allyltrimethoxysilane, deionized water, and ethanol in solution 3 is 1.5:3.5:45; Step B2, add 3 g of functionalized calcium carbonate to a mixture of 80 mL of isopropanol and 20 mL of deionized water, and heat to 70°C, then add 0.02 mol of acrylic acid and 0.012 g of ammonium persulfate, raise the system temperature to 95°C, continue the reaction for 2 h, filter and dry to obtain PAA@calcium carbonate material; Step B3, add 3g of PAA@calcium carbonate material to 20mL of 8wt% aluminum chloride solution and ultrasonically treat for 10min, then add 40mL of saturated ammonia solution, and react at 50°C and 3.8MPa for 3h, then react at 15°C and vacuum conditions for 2h, filter and dry to obtain a reinforced filler. Example

[0018] A method for preparing low-smoke flame-retardant rubber comprises the following steps: 40 parts of nitrile rubber, 20 parts of EPDM rubber, 15 parts of natural rubber, 5 parts of polystyrene, 10 parts of the modified flame retardant prepared in Example 1, 10 parts of the reinforcing filler prepared in Example 1, 2 parts of silane coupling agent (KH-550), 5 parts of sulfur, 0.5 parts of vulcanization accelerator TMTD, and 0.2 parts of antioxidant 1010; Step S1, weighing raw materials by weight, adding nitrile rubber, EPDM rubber, natural rubber and polystyrene into an internal mixer, and mixing at 60° C. for 8 minutes to obtain a mixed rubber material; Step S2, adding the mixed rubber material, the modified flame retardant prepared in Example 1, the reinforcing filler prepared in Example 1, and the antioxidant 1010 into an open mill, mixing at 90° C. for 5 min, then adding sulfur, a vulcanization accelerator TMTD, and a silane coupling agent (KH-550), and continuing to mix at 40° C. for 1 min, thinning through 6 times, and discharging a sheet to obtain a sheet; Step S3, vulcanizing and molding the sheet on a flat vulcanizer to obtain the smoke-suppressing and flame-retardant rubber. Example

[0019] A method for preparing low-smoke flame-retardant rubber comprises the following steps: 50 parts of nitrile rubber, 25 parts of EPDM rubber, 20 parts of natural rubber, 10 parts of polystyrene, 15 parts of the modified flame retardant prepared in Example 2, 13 parts of the reinforcing filler prepared in Example 2, 3 parts of silane coupling agent (KH-550), 6 parts of sulfur, 1 part of vulcanization accelerator TMTD, and 0.6 parts of antioxidant 1010; Step S1, weighing raw materials by weight, adding nitrile rubber, EPDM rubber, natural rubber and polystyrene into an internal mixer, and mixing at 65° C. for 10 minutes to obtain a mixed rubber material; Step S2, adding the mixed rubber material, the modified flame retardant prepared in Example 2, the reinforcing filler prepared in Example 2, and the antioxidant 1010 into an open mill, mixing at 100° C. for 7 minutes, then adding sulfur, a vulcanization accelerator TMTD, and a silane coupling agent (KH-550), and mixing at 50° C. for 2 minutes, thinning through 7 times, and discharging a sheet to obtain a sheet; Step S3, vulcanizing and molding the sheet on a flat vulcanizer to obtain the smoke-suppressing and flame-retardant rubber. Example

[0020] A method for preparing low-smoke flame-retardant rubber comprises the following steps: 60 parts of nitrile rubber, 30 parts of EPDM rubber, 25 parts of natural rubber, 15 parts of polystyrene, 20 parts of the modified flame retardant prepared in Example 3, 16 parts of the reinforcing filler prepared in Example 3, 4 parts of silane coupling agent (KH-550), 7 parts of sulfur, 2 parts of vulcanization accelerator TMTD, 1 part of antioxidant 1010; Step S1, weighing raw materials by weight, adding nitrile rubber, EPDM rubber, natural rubber and polystyrene into an internal mixer, and mixing at 70° C. for 12 minutes to obtain a mixed rubber material; Step S2, adding the mixed rubber material, the modified flame retardant prepared in Example 3, the reinforcing filler prepared in Example 3, and the antioxidant 1010 into an open mill, mixing at 120° C. for 10 min, then adding sulfur, a vulcanization accelerator TMTD, and a silane coupling agent (KH-550), and mixing at 60° C. for 3 min, thinning 8 times, and discharging a sheet to obtain a sheet; Step S3, vulcanizing and molding the sheet on a flat vulcanizer to obtain the smoke-suppressing and flame-retardant rubber.

[0021] Comparative Example 1 This comparative example is a flame retardant rubber, which differs from Example 6 in that diethyl ethyl phosphate flame retardant is used instead of the modified flame retardant prepared in Example 3, and the rest are the same.

[0022] Comparative Example 2 This comparative example is a flame retardant rubber, which differs from Example 6 in that calcium carbonate is used instead of the reinforcing filler prepared in Example 3, and the rest are the same.

[0023] The rubber prepared in Examples 4-6 and Comparative Examples 1-2 was subjected to performance tests: Mechanical properties test: tensile properties test according to GB / T 1040.1-2018 standard; Smoke density test: Tested in accordance with GB / T 8323.2-2018 standard;. Flame retardant performance test: Use UL94 combustion test machine to test the flame retardant performance of the sample The test results are shown in the following table: It can be seen from the above table that after the mechanical property test, the tensile strength of the rubber material prepared by the present invention is 15.4MPa-16.3MPa, indicating that it has good mechanical properties; after the smoke density and flame retardant performance tests, the smoke density is 175-199, and the combustion level is V-0, indicating that it has excellent smoke suppression and flame retardant properties.

[0024] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A low-smoke flame-retardant rubber, characterized in that: The invention comprises the following raw materials in parts by weight: 40-60 parts of nitrile rubber, 20-30 parts of EPDM rubber, 15-25 parts of natural rubber, 5-15 parts of polystyrene, 10-20 parts of modified flame retardant, 10-16 parts of reinforcing filler, 2-4 parts of silane coupling agent, 5-7 parts of sulfur, 0.5-2 parts of vulcanization accelerator and 0.2-1 parts of antioxidant; The modified flame retardant is prepared by the following steps: Step A1, (3-aminopropyl)trimethoxysilane and triethylamine are added to dichloromethane and mixed evenly, and then dimethyl chlorophosphate is added dropwise in an ice-water bath, and stirring is continued for 40-60 minutes, the system temperature is raised to room temperature, stirring is continued for 8-12 hours, and then filtered, washed, and vacuum dried to obtain phosphoric acid ester silane; Step A2, adding methyltrimethoxysilane and phosphoric acid ester silane to the ethanol solution, stirring at a speed of 400-600 rpm for 2-3 hours, then adding γ-(2,3-epoxypropoxy)propyltrimethoxysilane and allyltrimethoxysilane, continuing to stir for 1-2 hours, then adding ammonia water and stopping stirring, transferring to a 60° C. water bath and standing for 30-60 minutes, centrifuging, washing, and drying to obtain functionalized organosilicon microspheres; Step A3, dispersing 4-aminophthalic acid in ethanol, recorded as solution 1; adding functionalized organosilicon microspheres to ethanol and dispersing them evenly, then adding solution 1, and heating to 50-60° C., reacting for 5-7 hours, filtering, washing, and drying to obtain modified organosilicon microspheres; Step A4, adding (CH3COO)2Ni·4H2O into ethanol and dispersing it evenly, recorded as solution 2; dispersing the modified silicone microspheres in ethanol, and then adding solution 2 dropwise, adjusting the pH to 6-8, and then raising the temperature to 60-80°C, reacting for 2-3h, filtering, washing, and vacuum drying to obtain the modified flame retardant.

2. The low-smoke flame-retardant rubber according to claim 1, characterized in that: In step A1, the usage ratio of (3-aminopropyl)trimethoxysilane, triethylamine, dichloromethane and dimethyl chlorophosphate is 0.1-0.3 mol: 0.1-0.3 mol: 500 mL: 0.1-0.3 mol.

3. The low-smoke flame-retardant rubber according to claim 1, characterized in that: In step A2, the usage ratio of methyltrimethoxysilane, phosphate-containing silane, ethanol solution, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and allyltrimethoxysilane is 0.1-0.5 mol: 0.05-0.1 mol: 200 mL: 0.01-0.03 mol: 0.005-0.01 mol, and the volume ratio of ethanol to deionized water in the ethanol solution is 1:

1.

4. The low-smoke flame-retardant rubber according to claim 1, characterized in that: In step A3, the dosage ratio of the functionalized organosilicon microspheres, ethanol and solution 1 is 1 g: 50 mL: 20 mL, and the dosage ratio of 4-aminophthalic acid and ethanol in solution 1 is 0.1-0.5 g: 20 mL.

5. The low-smoke flame-retardant rubber according to claim 1, characterized in that: In step A4, the amount ratio of modified organosilicon microspheres, ethanol and solution 2 is 1 g:100 mL:100 mL, and the amount ratio of (CH3COO)2Ni·4H2O and ethanol in solution 2 is 0.05-0.3 g:100 mL.

6. The low-smoke flame-retardant rubber according to claim 1, characterized in that: The reinforcing filler is prepared by the following steps: Step B1, adding allyltrimethoxysilane to a mixture of deionized water and ethanol, recorded as solution 3; adding calcium carbonate to isopropanol and dispersing it evenly, then adding solution 3, and reacting at 70-90° C. for 3-5 hours, centrifuging, washing, and drying to obtain functionalized calcium carbonate; Step B2, adding functionalized calcium carbonate to a mixture of isopropanol and deionized water, and heating to 60-70°C, then adding acrylic acid and ammonium persulfate, raising the system temperature to 85-95°C, continuing the reaction for 1-2h, filtering and drying, and obtaining PAA@calcium carbonate material; Step B3, add the PAA@calcium carbonate material to an 8-12wt% aluminum chloride solution and ultrasonically treat it for 10 minutes, then add a saturated ammonia solution dropwise, and react at 40-50°C and 3.5-3.8MPa for 2-3 hours, then react at 10-15°C and vacuum conditions for 1-2 hours, filter, and dry to obtain a reinforced filler.

7. The low-smoke flame-retardant rubber according to claim 6, characterized in that: The amount ratio of calcium carbonate, isopropanol and solution 3 in step B1 is 1-3 g:50 mL:50 mL, and the volume ratio of allyltrimethoxysilane, deionized water and ethanol in solution 3 is 0.5-1.5:3.5-4.5:

45.

8. The low-smoke flame-retardant rubber according to claim 6, characterized in that: In step B2, the dosage ratio of functionalized calcium carbonate, isopropanol, deionized water, acrylic acid and ammonium persulfate is 1-3 g: 80 mL: 20 mL: 0.005-0.02 mol: 0.003-0.012 g.

9. The low-smoke flame-retardant rubber according to claim 6, characterized in that: In step B3, the dosage ratio of PAA@calcium carbonate material, aluminum chloride solution and saturated ammonia solution is 1-3 g: 10-20 mL: 20-40 mL.

10. The method for preparing low-smoke flame-retardant rubber according to claim 1, characterized in that: The following steps are involved: Step S1, weighing raw materials by weight, adding nitrile rubber, EPDM rubber, natural rubber and polystyrene into an internal mixer, and mixing at 60-70° C. for 8-12 minutes to obtain a mixed rubber material; Step S2, adding the mixed rubber material, modified flame retardant, reinforcing filler and antioxidant into an open mill, mixing at 90-120° C. for 5-10 min, then adding sulfur, vulcanization accelerator and silane coupling agent, continuing to mix at 40-60° C. for 1-3 min, thinning 6-8 times, and discharging to obtain a sheet; Step S3, vulcanizing and molding the sheet on a flat vulcanizer to obtain the smoke-suppressing and flame-retardant rubber.

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