Halogen-free flame-retardant heat-resistant rubber and preparation method thereof

Abstract

The invention discloses halogen-free flame-retardant heat-resistant rubber and a preparation method thereof, and relates to the technical field of rubber. According to the invention, through hydroxylation treatment of lamellar porous carbon, adsorption sites are formed, growth of nano nickel on the surface and in holes of the porous carbon is promoted, a metal network is formed, phonon scattering interference is reduced, interface thermal resistance is reduced, and thermal conductivity is improved. And the nanosheet layer filler is uniformly dispersed in the rubber matrix to form a heat-conducting network, so that heat conduction is rapid, oxidative degradation of chain segments is avoided, and the thermal stability and flame retardance are improved. Meanwhile, the invention further relates to a novel flame-retardant microsphere preparation technology, microspheres rich in Si and P elements are formed by polymerizing a phosphorus-containing silane compound and the like, the carbon residue rate is increased, the microspheres are compounded with a flaky filler, the carbon residue rate of a cable material is increased, combustion heat is rapidly conducted, free radical reaction is reduced, combustion toxicity is reduced, and a low-smoke flame-retardant rubber material is prepared.

Description

Technical Field

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

[0002] Ethylene propylene diene monomer (EPDM) is an ethylene-propylene-non-conjugated diene copolymer with good weather resistance, electrical insulation, ozone resistance and chemical resistance. The flame retardant modification of EPDM aims to overcome the flammability of EPDM and improve its application safety. Currently, commercial flame retardant EPDM materials mainly use a bromine-antimony oxide flame retardant system, but halogen-containing flame retardants are gradually being abandoned by new environmental regulations because they produce toxic and corrosive gases during combustion. Therefore, the research on halogen-free flame retardant EPDM has attracted widespread attention recently.

[0003] At present, most halogen-free flame-retardant EPDM materials are added with environmentally friendly magnesium hydroxide, aluminum hydroxide or used in conjunction with other compounding agents. Due to the low flame retardant efficiency of hydroxides, the magnesium hydroxide filling amount must be as high as 200 parts by weight relative to 100 parts by weight of EPDM to make EPDM reach the FV-0 flame retardant level. At this time, the physical properties of EPDM, especially the elongation at break, become very poor.

[0004] The rubber industry is one of the important basic industries of the national economy. It not only provides people with daily necessities, medical and other light industrial rubber products that are indispensable in daily life, but also provides various rubber production equipment or rubber parts to heavy industries and emerging industries such as mining, transportation, construction, machinery, and electronics. Many rubber products have high requirements for the heat resistance of rubber. For example, rubber conveyor belts are widely used in high-temperature working environments such as metallurgy, coking, and building materials. The materials they transport are sometimes at very high temperatures. If the heat resistance of the rubber conveyor belt is insufficient, its service life will be greatly reduced. Summary of the invention

[0005] The object of the present invention is to provide a halogen-free flame-retardant and heat-resistant rubber and a preparation method thereof, so as to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a halogen-free flame-retardant and heat-resistant rubber, comprising, by weight, 40 to 60 parts of EPDM rubber, 15 to 35 parts of vinyl silicone rubber, 0.5 to 1.5 parts of sulfur, 0.5 to 1.5 parts of accelerator DCP, 0.5 to 1.5 parts of accelerator DM, 10 to 15 parts of flame-retardant microspheres, 5 to 10 parts of flaky fillers, and 1 to 5 parts of stearic acid;

[0007] The preparation method of the flame-retardant microspheres is as follows: Mix diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol, stir evenly at 250 rpm, add ethanol in an amount 0.1 to 0.5 times the mass of diethylphosphorylethyltriethoxysilane to disperse it until transparent, then dropwise add a hydrochloric acid solution in an amount 0.2 to 0.6 times the mass of diethylphosphorylethyltriethoxysilane, heat up to 75 °C, continue stirring and reacting for 5 h, and quickly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution; Under stirring at 800 rpm, mix the prepolymer solution and water to form an emulsion, then add ammonia water to make the pH of the emulsion reach 10, continue stirring and reacting for 24 h, stand still and filter to obtain a white precipitate; Rinse the precipitate twice with water, put the obtained precipitate into an oven, dry it at 100 °C for 10 h to obtain the flame-retardant microspheres.

[0008] Further, the particle size of the flame-retardant microspheres is in the range of 15 - 20 microns.

[0009] Further, the mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 40 - 60:30 - 40:160:10 - 15.

[0010] Further, the concentration of the hydrochloric acid solution is 2 mol / L.

[0011] Further, the mass ratio of the prepolymer solution and water is 1:10 - 14.

[0012] Further, the preparation method of the flaky filler is as follows: After hydroxylating the lamellar porous carbon, mix it with nickel acetate hexahydrate and deionized water in a mass ratio of 0.1 - 1:1 - 5:100, under the condition of 30 - 50 kHz, ultrasonicate for 1 - 3 h, then add catechin in an amount 7 - 10 times the mass of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation to obtain a product.

[0013] Further, the lamellar porous carbon is prepared with reference to CN201910619097.7 and then ground to a particle size of 200 - 500 nm.

[0014] Further, the γ-ray dose is 20 KGy / h and the irradiation time is 10 h.

[0015] Further, the preparation method of the halogen-free flame-retardant heat-resistant rubber is as follows: Put ethylene propylene diene monomer rubber, vinyl silicone rubber, sulfur, accelerator DCP, accelerator DM, flame-retardant microspheres, flaky filler, and stearic acid into an open mill for mixing for 5 - 10 min, then carry out secondary vulcanization and cool to room temperature.

[0016] Further, the vulcanization process is as follows: vulcanize at 150 - 170 °C and 8 - 12 MPa for 20 - 30 min, and then place it in an oven for secondary vulcanization at 170 - 180 °C for 4 - 6 h.

[0017] Further, the ethylene propylene diene monomer rubber is LANXESS 5962 from Germany.

[0018] Further, the vinyl silicone rubber has an ethylene content of 0.1 - 0.3 mol% and a molecular weight of 450,000 - 700,000.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] The present invention hydroxylates the lamellar porous carbon, and the hydroxyl groups form adsorption sites, which is beneficial to the reduction and growth of nano - nickel on the surface and in the pores of the lamellar porous carbon, forming a continuous or semi - continuous metal network on the surface and in the pores of the porous carbon, reducing the interference of pores on phonon scattering, reducing the interfacial thermal resistance, and effectively improving the thermal conductivity of the lamellar filler due to the thermal conductivity of nano - nickel itself. The lamellar filler is uniformly dispersed in the system in the form of nanosheets and has a good bonding force with the rubber matrix, forming a continuous thermal conduction network in the rubber matrix. By quickly conducting the internal heat, it avoids the oxidative degradation of chain segments caused by local temperature rise, delays thermal aging, and improves the thermal stability of the rubber. At the same time, the rapid heat dissipation ability of the lamellar filler reduces the surface temperature of the material, delays thermal decomposition and the release of combustible gases, and improves the flame retardancy of the rubber.

[0021] The present invention relates to a preparation technology of a novel flame - retardant microsphere. This technology polymerizes a phosphorus - based silane compound, a double - bond silane compound, and tetraethyl orthosilicate to form a flame - retardant microsphere rich in silicon (Si) and phosphorus (P) elements. This microsphere has a high char residue rate and can be effectively compounded with flaky fillers, significantly improving the char residue rate of the cable material in a high - temperature environment. It can also quickly conduct the heat of combustion, prevent excessive heat accumulation during combustion, reduce free - radical reactions, and reduce the toxic gases generated by incomplete combustion, thereby effectively reducing the combustion toxicity and preparing a rubber material with excellent low - smoke flame - retardant properties.

[0022] The present invention adds vinyl silicone rubber to ethylene propylene diene monomer rubber and uses them together. By using the ethylene propylene diene monomer rubber and vinyl silicone rubber to form a three - dimensional network interpenetrating structure, the advantages of both are fully utilized. In the present invention, it becomes possible for the ethylene propylene diene monomer rubber and vinyl silicone rubber to cross - link simultaneously and without interference, avoiding the drawback of the single heat - resistant component in the existing heat - resistant rubber formula and the situation of heat - resistant component failure under complex thermal conditions, and playing an efficient complementary heat - resistant role. Detailed implementation mode

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] (1) Mix diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol. After stirring evenly at 250 rpm, add ethanol 0.1 times the mass of diethylphosphorylethyltriethoxysilane to disperse it until transparent, and then dropwise add a 2 mol / L hydrochloric acid solution 0.2 times the mass of diethylphosphorylethyltriethoxysilane. Heat to 75 °C and continue stirring and reacting for 5 h. Rapidly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution. Under stirring at 800 rpm, mix the prepolymer solution and water in a mass ratio of 1:10 to form an emulsion, then add ammonia water to make the pH of the emulsion reach 10, continue stirring and reacting for 24 h, stand still and filter to obtain a white precipitate. Rinse the precipitate twice with water, put the obtained precipitate into an oven, dry it at 100 °C for 10 h to obtain flame-retardant microspheres with a particle size of 15 microns. The mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 40:30:160:10;

[0026] (2) Place lamellar porous carbon with a particle size of 200 nm in a mixed solution of hydrogen peroxide and sulfuric acid, ultrasonicate at 30 kHz for 30 min. After ultrasonication, perform a water bath treatment at 50 °C for 20 min, wash 3 times with water first, and then wash 3 times with absolute ethanol, and dry at 50 °C for 5 h to obtain hydroxylated lamellar porous carbon. The mass concentration of the hydrogen peroxide used is about 30%, the mass concentration of the sulfuric acid is about 98%, and the mass ratio of hydrogen peroxide to sulfuric acid is 1:10. Mix hydroxylated lamellar porous carbon, nickel acetate hexahydrate, and deionized water in a mass ratio of 0.1:1:100, ultrasonicate for 1 - 3 h under the condition of 30 kHz, then add catechin 7 times the mass of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation. The γ-ray dose is 20 KGy / h, and the irradiation time is 10 h. Filter and dry at 50 °C for 5 h to obtain flaky fillers;

[0027] (3) Put 40 parts of ethylene propylene diene monomer rubber, 15 parts of vinyl silicone rubber, 0.5 part of sulfur, 0.5 part of accelerator DCP, 0.5 part of accelerator DM, 10 parts of flame-retardant microspheres, 5 parts of flaky fillers, and 1 part of stearic acid into an open mill for mixing for 5 min, vulcanize at 150 °C and 8 MPa for 20 min, and then perform secondary vulcanization in an oven at 170 °C for 4 h, and cool to room temperature.

[0028] Example 2

[0029] (1) Mix diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol. After stirring evenly at 250 rpm, add ethanol in an amount 0.3 times the mass of diethylphosphorylethyltriethoxysilane to disperse it until transparent. Then, dropwise add a 2 mol / L hydrochloric acid solution in an amount 0.4 times the mass of diethylphosphorylethyltriethoxysilane. Heat up to 75 °C and continue stirring and reacting for 5 h. Rapidly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution. Under stirring at 800 rpm, mix the prepolymer solution and water in a mass ratio of 1:12 to form an emulsion. Then, add ammonia water to make the pH of the emulsion reach 10, continue stirring and reacting for 24 h, let it stand, and filter to obtain a white precipitate. Rinse the precipitate twice with water, put the obtained precipitate into an oven, dry it at 100 °C for 10 h to obtain flame-retardant microspheres with a particle size of 18 microns. The mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 50:35:160:12;

[0030] (2) Place lamellar porous carbon with a particle size of 350 nm in a mixed solution of hydrogen peroxide and sulfuric acid, ultrasonicate at 40 kHz for 60 min. After ultrasonication, perform a water bath treatment at 65 °C for 35 min. First, wash it 3 times with water, then wash it 3 times with absolute ethanol, and dry it at 50 °C for 5 h to obtain hydroxylated lamellar porous carbon. The mass concentration of the hydrogen peroxide used is about 30%, the mass concentration of the sulfuric acid is about 98%, and the mass ratio of hydrogen peroxide to sulfuric acid is 10:1. Mix hydroxylated lamellar porous carbon, nickel acetate hexahydrate, and deionized water in a mass ratio of 0.5:3:100, ultrasonicate for 2 h under the condition of 40 kHz, then add catechin in an amount 8 times the mass of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation. The γ-ray dose is 20 kGy / h, and the irradiation time is 10 h. Filter and dry it at 50 °C for 5 h to obtain flaky fillers;

[0031] (3) Charge 50 parts of ethylene propylene diene monomer rubber, 25 parts of vinyl silicone rubber, 1 part of sulfur, 1 part of accelerator DCP, 1 part of accelerator DM, 12 parts of flame-retardant microspheres, 7 parts of flaky fillers, and 3 parts of stearic acid into an open mill for mixing for 8 min. Vulcanize at 160 °C and 10 MPa for 25 min, and then place it in an oven at 175 °C for secondary vulcanization for 5 h, and cool to room temperature.

[0032] Example 3

[0033] (1) Mix diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol. After stirring evenly at 250 rpm, add ethanol in an amount 0.5 times the mass of diethylphosphorylethyltriethoxysilane to disperse it until transparent. Then, dropwise add a 2 mol / L hydrochloric acid solution in an amount 0.6 times the mass of diethylphosphorylethyltriethoxysilane. Heat the mixture to 75 °C and continue stirring and reacting for 5 h. Rapidly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution. Under stirring at 800 rpm, mix the prepolymer solution and water at a mass ratio of 1:14 to form an emulsion. Then, add ammonia water to adjust the pH of the emulsion to 10, continue stirring and reacting for 24 h, let it stand, and filter to obtain a white precipitate. Rinse the precipitate twice with water, put the obtained precipitate into an oven, and dry it at 100 °C for 10 h to obtain flame-retardant microspheres with a particle size of 20 microns. The mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 60:40:160:15;

[0034] (2) Place lamellar porous carbon with a particle size of 500 nm in a mixed solution of hydrogen peroxide and sulfuric acid, and ultrasonicate it at 50 kHz for 90 min. After the ultrasonication is completed, perform a water bath treatment at 80 °C for 50 min. First, wash it with water 3 times, and then wash it with absolute ethanol 3 times. Dry it at 50 °C for 5 h to obtain hydroxylated lamellar porous carbon. The mass concentration of the hydrogen peroxide used is about 30%, the mass concentration of the sulfuric acid is about 98%, and the mass ratio of hydrogen peroxide to sulfuric acid is 10:1. Mix the hydroxylated lamellar porous carbon, nickel acetate hexahydrate, and deionized water at a mass ratio of 1:5:100, ultrasonicate it at 50 kHz for 3 h, then add catechin in an amount 10 times the mass of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation. The γ-ray dose is 20 kGy / h, and the irradiation time is 10 h. Filter and dry it at 50 °C for 5 h to obtain flaky fillers;

[0035] (3) Put 60 parts of ethylene propylene diene monomer rubber, 35 parts of vinyl silicone rubber, 1.5 parts of sulfur, 1.5 parts of accelerator DCP, 1.5 parts of accelerator DM, 15 parts of flame-retardant microspheres, 10 parts of flaky fillers, and 5 parts of stearic acid into an open mill for mixing for 10 min. Vulcanize it at 170 °C and 12 MPa for 30 min, and then put it into an oven for secondary vulcanization at 180 °C for 6 h, and cool it to room temperature.

[0036] Comparative Example 1 (without adding (4-vinylphenyl)trimethoxysilane)

[0037] (1) Mix diethylphosphorylethyltriethoxysilane, tetraethyl orthosilicate, and polyethylene glycol, stir evenly at 250 rpm, add ethanol in an amount 0.5 times the mass of diethylphosphorylethyltriethoxysilane to disperse it until transparent, then gradually add a 2 mol / L hydrochloric acid solution in an amount 0.6 times the mass of diethylphosphorylethyltriethoxysilane, raise the temperature to 75 °C, continue stirring and reacting for 5 h, quickly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution; under stirring at 800 rpm, mix the prepolymer solution and water in a mass ratio of 1:14 to form an emulsion, then add ammonia water to make the pH of the emulsion reach 10, continue stirring and reacting for 24 h, let it stand and filter to obtain a white precipitate; rinse the precipitate twice with water, put the obtained precipitate into an oven, dry it at 100 °C for 10 h to obtain flame-retardant microspheres with a particle size of 20 microns; the mass ratio of diethylphosphorylethyltriethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 60:160:15;

[0038] (2) Place lamellar porous carbon with a particle size of 500 nm in a mixed solution of hydrogen peroxide and sulfuric acid, ultrasonicate at 50 kHz for 90 min, after the sonication is completed, perform a water bath treatment at 80 °C for 50 min, wash it with water 3 times first, and then wash it with absolute ethanol 3 times, dry it at 50 °C for 5 h to obtain hydroxylated lamellar porous carbon; the mass concentration of the hydrogen peroxide used is about 30%, the mass concentration of the sulfuric acid is about 98%, and the mass ratio of hydrogen peroxide to sulfuric acid is 10:1; mix hydroxylated lamellar porous carbon, nickel acetate hexahydrate, and deionized water in a mass ratio of 1:5:100, under the condition of 50 kHz, ultrasonicate for 3 h, then add catechin in an amount 10 times the mass of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation, the γ-ray dose is 20 kGy / h, the irradiation time is 10 h, filter, and dry it at 50 °C for 5 h to obtain flaky fillers;

[0039] (3) Put 60 parts of ethylene propylene diene monomer rubber, 35 parts of vinyl silicone rubber, 1.5 parts of sulfur, 1.5 parts of accelerator DCP, 1.5 parts of accelerator DM, 15 parts of flame-retardant microspheres, 10 parts of flaky fillers, and 5 parts of stearic acid into an open mill for mixing for 10 min, vulcanize at 170 °C and 12 MPa for 30 min, and perform secondary vulcanization in an oven at 180 °C for 6 h, then cool to room temperature.

[0040] Comparative Example 2 (without adding diethylphosphorylethyltriethoxysilane)

[0041] (1) Mix (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol. After stirring evenly at 250 rpm, add ethanol with a mass 0.5 times that of (4-vinylphenyl)trimethoxysilane to disperse it until transparent. Then, dropwise add a 2 mol / L hydrochloric acid solution with a mass 0.6 times that of (4-vinylphenyl)trimethoxysilane. Heat up to 75 °C and continue stirring and reacting for 5 h. Rapidly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution. Under stirring at 800 rpm, mix the prepolymer solution and water at a mass ratio of 1:14 to form an emulsion. Then, add ammonia water to adjust the pH of the emulsion to 10, continue stirring and reacting for 24 h, let it stand, and filter to obtain a white precipitate. Rinse the precipitate twice with water, put the obtained precipitate into an oven, dry it at 100 °C for 10 h to obtain flame-retardant microspheres with a particle size of 20 microns. The mass ratio of (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 40:160:15;

[0042] (2) Place lamellar porous carbon with a particle size of 500 nm in a mixed solution of hydrogen peroxide and sulfuric acid, ultrasonicate at 50 kHz for 90 min. After ultrasonication, perform a water bath treatment at 80 °C for 50 min. Wash it with water 3 times first, and then wash it with absolute ethanol 3 times. Dry it at 50 °C for 5 h to obtain hydroxylated lamellar porous carbon. The mass concentration of the hydrogen peroxide used is about 30%, the mass concentration of the sulfuric acid is about 98%, and the mass ratio of hydrogen peroxide to sulfuric acid is 10:1. Mix hydroxylated lamellar porous carbon, nickel acetate hexahydrate, and deionized water at a mass ratio of 1:5:100, ultrasonicate under the condition of 50 kHz for 3 h, then add catechin with a mass 10 times that of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation. The γ-ray dose is 20 kGy / h, and the irradiation time is 10 h. Filter and dry it at 50 °C for 5 h to obtain flaky fillers;

[0043] (3) Put 60 parts of ethylene propylene diene monomer rubber, 35 parts of vinyl silicone rubber, 1.5 parts of sulfur, 1.5 parts of accelerator DCP, 1.5 parts of accelerator DM, 15 parts of flame-retardant microspheres, 10 parts of flaky fillers, and 5 parts of stearic acid into an open mill for mixing for 10 min. Vulcanize at 170 °C and 12 MPa for 30 min, and then place it in an oven at 180 °C for secondary vulcanization for 6 h, and cool to room temperature.

[0044] Comparative Example 3 (without adding flame-retardant microspheres)

[0045] (1) Place the lamellar porous carbon with a particle size of 500 nm in a mixed solution of hydrogen peroxide and sulfuric acid, ultrasonicate at 50 kHz for 90 min. After the sonication is completed, perform a water bath treatment at 80 °C for 50 min. Wash it with water 3 times first, then wash it with absolute ethanol 3 times, and dry it at 50 °C for 5 h to obtain hydroxylated lamellar porous carbon; the mass concentration of the hydrogen peroxide used is about 30%, the mass concentration of the sulfuric acid is about 98%, and the mass ratio of hydrogen peroxide to sulfuric acid is 10:1; mix the hydroxylated lamellar porous carbon, nickel acetate hexahydrate, and deionized water according to a mass ratio of 1:5:100, ultrasonicate for 3 h under the condition of 50 kHz, then add catechin which is 10 times the mass of nickel acetate hexahydrate as a radical scavenger, and then carry out the reaction under γ-ray irradiation. The γ-ray dose is 20 kGy / h, and the irradiation time is 10 h. Filter and dry at 50 °C for 5 h to obtain flaky fillers;

[0046] (2) Put 60 parts of ethylene propylene diene monomer rubber, 35 parts of vinyl silicone rubber, 1.5 parts of sulfur, 1.5 parts of accelerator DCP, 1.5 parts of accelerator DM, 10 parts of flaky fillers, and 5 parts of stearic acid into an open mill for mixing for 10 min, vulcanize at 170 °C and 12 MPa for 30 min, and then put it into an oven for secondary vulcanization at 180 °C for 6 h, and cool to room temperature.

[0047] Comparative Example 4 (only using lamellar porous carbon with a particle size of 500 nm)

[0048] (1) Mix diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol. After stirring evenly at 250 rpm, add ethanol which is 0.5 times the mass of diethylphosphorylethyltriethoxysilane to disperse it until transparent, and then gradually add 2 mol / L hydrochloric acid solution which is 0.6 times the mass of diethylphosphorylethyltriethoxysilane. Heat up to 75 °C and continue stirring and reacting for 5 h. Rapidly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution; under stirring at 800 rpm, mix the prepolymer solution and water according to a mass ratio of 1:14 to form an emulsion, then add ammonia water to make the pH of the emulsion reach 10, and continue stirring and reacting for 24 h. Let it stand and filter to obtain a white precipitate; rinse the precipitate twice with water, put the obtained precipitate into an oven, and dry it at 100 °C for 10 h to obtain flame-retardant microspheres with a particle size of 20 microns; the mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 60:40:160:15;

[0049] (2) 60 parts of ethylene propylene diene monomer rubber, 35 parts of vinyl silicone rubber, 1.5 parts of sulfur, 1.5 parts of accelerator DCP, 1.5 parts of accelerator DM, 15 parts of flame retardant microspheres, 10 parts of lamellar porous carbon with a particle size of 500 nm, and 5 parts of stearic acid were put into an open mill for mixing for 10 min, vulcanized at 170 °C and 12 MPa for 30 min, and then put into an oven for secondary vulcanization at 180 °C for 6 h, and cooled to room temperature.

[0050] Comparative Example 5 (without adding flaky filler)

[0051] (1) Diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol were mixed, and after stirring evenly at 250 rpm, ethanol 0.5 times the mass of diethylphosphorylethyltriethoxysilane was added to disperse it to transparency, and then a 2 mol / L hydrochloric acid solution 0.6 times the mass of diethylphosphorylethyltriethoxysilane was added dropwise. The temperature was raised to 75 °C, and stirring reaction was continued for 5 h. Ethanol in the system was quickly distilled off under reduced pressure to obtain a prepolymer solution; under stirring at 800 rpm, the prepolymer solution and water were mixed at a mass ratio of 1:14 to form an emulsion, and then ammonia water was added to make the pH of the emulsion reach 10, and stirring reaction was continued for 24 h. It was left standing and filtered to obtain a white precipitate; the precipitate was rinsed twice with water, and the obtained precipitate was put into an oven and dried at 100 °C for 10 h to obtain flame retardant microspheres with a particle size of 20 microns; the mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol was 60:40:160:15;

[0052] (2) 60 parts of ethylene propylene diene monomer rubber, 35 parts of vinyl silicone rubber, 1.5 parts of sulfur, 1.5 parts of accelerator DCP, 1.5 parts of accelerator DM, 15 parts of flame retardant microspheres, and 5 parts of stearic acid were put into an open mill for mixing for 10 min, vulcanized at 170 °C and 12 MPa for 30 min, and then put into an oven for secondary vulcanization at 180 °C for 6 h, and cooled to room temperature.

[0053] Performance Test

[0054] (1) Vertical burning time and flame retardant grade

[0055] The vertical burning time (s) was tested according to the test method of GB / T2408—1996, and the flame retardant grade was determined according to the measured vertical burning time (s). The sample size was 125 mm × 12.5 mm × 1.6 mm.

[0056] (2) Oxygen index %

[0057] Tested according to GB / T2406—1993, the sample size was 85 mm × 10 mm × 3.2 mm.

[0058] (3) Elongation at break and tear strength

[0059] Tested in accordance with GB / T528—1998, tensile rate 500mm / min.

[0060] Table 1

[0061]

[0062]

[0063] The present invention hydroxylates the lamellar porous carbon to form adsorption sites, promotes the growth of nano-nickel on the surface and in the pores of the porous carbon to form a metal network, reduces the interference of phonon scattering, lowers the interfacial thermal resistance, and improves the thermal conductivity. The nano-sheet fillers are uniformly dispersed in the rubber matrix to form a thermal conduction network, conduct heat quickly, avoid the oxidative degradation of the chain segments, and improve the thermal stability and flame retardancy. At the same time, the present invention also relates to a new type of flame-retardant microsphere preparation technology. By polymerizing phosphorus-containing silane compounds, etc., microspheres rich in Si and P elements are formed to increase the char residue rate. When compounded with the sheet-like fillers, the char residue rate of the cable material is increased, the combustion heat is conducted quickly, the free radical reaction is reduced, the combustion toxicity is lowered, and a low-smoke flame-retardant rubber material is prepared.

[0064] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A halogen-free flame-retardant and heat-resistant rubber, characterized in that, By weight parts, it includes 40-60 parts of ethylene propylene diene monomer rubber, 15-35 parts of vinyl silicone rubber, 0.5-1.5 parts of sulfur, 0.5-1.5 parts of accelerator DCP, 0.5-1.5 parts of accelerator DM, 10-15 parts of flame retardant microspheres, 5-10 parts of flaky filler, and 1-5 parts of stearic acid; The preparation method of the flame retardant microspheres is as follows: Mix diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol, stir evenly at 250 rpm, add ethanol with a mass 0.1-0.5 times that of diethylphosphorylethyltriethoxysilane to disperse it until transparent, then dropwise add a hydrochloric acid solution with a mass 0.2-0.6 times that of diethylphosphorylethyltriethoxysilane, raise the temperature to 75 °C, continue stirring and reacting for 5 h, and quickly distill off the ethanol in the system under reduced pressure to obtain a prepolymer solution; Under stirring at 800 rpm, mix the prepolymer solution and water to form an emulsion, then add ammonia water to make the pH of the emulsion reach 10, continue stirring and reacting for 24 h, stand still and filter to obtain a white precipitate; Rinse the precipitate twice with water, put the obtained precipitate into an oven, dry it at 100 °C for 10 h to obtain the flame retardant microspheres.

2. The halogen-free flame-retardant and heat-resistant rubber according to claim 1, wherein The particle size of the flame retardant microspheres is in the range of 15-20 microns.

3. The halogen-free flame-retardant and heat-resistant rubber according to claim 1, wherein The mass ratio of diethylphosphorylethyltriethoxysilane, (4-vinylphenyl)trimethoxysilane, tetraethyl orthosilicate, and polyethylene glycol is 40-60:30-40:160:10-15.

4. A halogen-free flame-retardant heat-resistant rubber according to claim 1, characterized in that, The concentration of the hydrochloric acid solution is 2 mol / L.

5. The halogen-free flame-retardant and heat-resistant rubber according to claim 1, characterized in that, The mass ratio of the prepolymer solution and water is 1:10-14.

6. The halogen-free flame-retardant heat-resistant rubber according to claim 1, characterized in that, The preparation method of the flaky filler is as follows: After hydroxylating the lamellar porous carbon, mix it with nickel acetate hexahydrate and deionized water according to a mass ratio of 0.1-1:1-5:100, under the condition of 30-50 kHz, ultrasonic for 1-3 h, then add catechin with a mass 7-10 times that of nickel acetate hexahydrate as a radical scavenger, and then carry out a reaction under γ-ray irradiation to obtain a product.

7. The halogen-free flame retardant heat-resistant rubber according to claim 6, characterized in that, The γ-ray dose is 20 KGy / h, and the irradiation time is 10 h.

8. A halogen-free flame-retardant and heat-resistant rubber according to claim 1, wherein The preparation method of the halogen-free flame retardant heat-resistant rubber is as follows: Put ethylene propylene diene monomer rubber, vinyl silicone rubber, sulfur, accelerator DCP, accelerator DM, flame retardant microspheres, flaky filler, and stearic acid into an open mill for mixing for 5-10 min, and then carry out secondary vulcanization and cool to room temperature.

9. The halogen-free flame-retardant heat-resistant rubber according to claim 8, characterized in that, The specific vulcanization process is as follows: Vulcanize at 150-170 °C and 8-12 MPa for 20-30 min, and put it into an oven for secondary vulcanization at 170-180 °C for 4-6 h.

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