A halogen-free, sulfur-free, environmentally friendly flame-retardant rubber foam material and preparation method thereof

Abstract

The present invention relates to the technical field of sulfur-free flame-retardant rubber, specifically to a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material and a preparation method thereof. The process includes the following steps: Step 1: plasticize methyl vinyl silicone rubber and natural rubber separately, mix the plasticized products with flame retardant, carbon black, plasticizer and auxiliary agent, and carry out internal mixing, open mixing, extrusion and parking in sequence to obtain a base material; Step 2: vulcanize the base material to obtain a flame-retardant rubber foam material. The flame-retardant rubber foam material includes the following materials by mass: 10 to 40 parts of methyl vinyl silicone rubber, 20 to 50 parts of natural rubber, 38 to 42 parts of flame retardant, 25 to 30 parts of carbon black, 10 to 18 parts of plasticizer, and 11 to 17 parts of auxiliary agent.

Description

Technical Field

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

[0002] Natural rubber is a material with good elasticity, electrical insulation, cold resistance and other comprehensive properties. Its market usage accounts for 30-40% of the total rubber, and it is widely used in various fields such as construction, aviation, automobiles, home appliances, packaging instruments, etc. Among them, due to its poor flame retardancy and medium resistance, its use in some occasions is affected; while methyl vinyl silicone rubber is a material with a highly saturated structure, with excellent oil resistance, heat resistance, chemical corrosion resistance, and tear resistance; mixing it with natural rubber to prepare foamed rubber materials can combine the advantages of the two rubbers, make up for each other's shortcomings, achieve performance complementarity, and expand the application range of the material.

[0003] However, in the prior art, the use of natural rubber and methyl vinyl silicone rubber to prepare foamed rubber materials faces the problem of poor interface performance between the two materials, which leads to uneven foaming of the overall foaming and a decrease in the mechanical properties of the rubber material. On the other hand, its flame retardancy is limited, and it is necessary to further introduce flame retardants to improve its flame retardancy, but it also has a dispersion problem, resulting in a decrease in overall performance. At the same time, sulfur is generally present in general flame retardant rubber foam materials, which reduces the environmental performance of the flame retardant rubber foam materials.

[0004] In summary, solving the above problems and preparing a halogen-free, sulfur-free, environmentally friendly flame-retardant rubber foam material is of great value. Summary of the invention

[0005] The object of the present invention is to provide a halogen-free, sulfur-free, environmentally friendly flame-retardant rubber foam material and a preparation method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing a halogen-free, sulfur-free, and environmentally friendly flame-retardant rubber foam material, comprising the following steps:

[0008] Step 1: Methyl vinyl silicone rubber and natural rubber are plasticized separately, and the plasticized products are mixed with flame retardant, carbon black, plasticizer and additives, and then the products are subjected to internal mixing, open mixing, extrusion and parking in sequence to obtain a base material;

[0009] Step 2: vulcanize the base material to obtain a flame retardant rubber foam material.

[0010] Furthermore, the flame retardant rubber foam material comprises the following materials in parts by weight: 10 to 40 parts of methyl vinyl silicone rubber, 20 to 50 parts of natural rubber, 38 to 42 parts of flame retardant, 25 to 30 parts of carbon black, 10 to 18 parts of plasticizer, and 11 to 17 parts of auxiliary agent.

[0011] Furthermore, the auxiliary agent includes the following materials by weight: 1 to 2 parts of metal-based accelerator, 1.6 to 2.5 parts of organic peroxide vulcanizing agent, 1 to 1.5 parts of antioxidant, 1 to 1.5 parts of dispersant, 0.8 to 1 part of cross-linking agent, 1.8 to 2 parts of foaming aid, and 3.8 to 6.5 parts of foaming agent.

[0012] Furthermore, the preparation method of the flame retardant comprises the following process:

[0013] Step 1: 2-aminopyridine-5-boric acid pinacol ester and triethylamine are added to 1,4-dioxane in sequence, stirred evenly, and a mixed solution of 1,4-dioxane containing vinylphosphonyl chloride is added, reacted at 45±5° C. for 6 to 8 hours, and post-treated to obtain a flame retardant monomer;

[0014] Step 2: adding hydrogen-containing polysiloxane, 3,7-dimethyl-1,6-octadiene, flame retardant monomer, 4-allylcatechol, platinum catalyst and borax to tetrahydrofuran in sequence, reacting at 65±5° C. for 2 to 4 hours under a nitrogen atmosphere, and post-treating to obtain modified polysiloxane;

[0015] Step 3: liquid isoprene, flame retardant monomer, 4-allylcatechol, and borax are sequentially added to xylene, reacted at 70±5° C. under a nitrogen atmosphere, and an initiator solution is added to react for 6 to 10 hours, and post-treated to obtain modified isoprene;

[0016] Step 4: Add modified polysiloxane and modified isoprene to xylene, and add ammonia water; add a xylene mixed solution containing tetrabutyl titanate under stirring, and stir for 1 to 2 hours; heat to 80±5°C and react for 1 to 1.5 hours; then heat to 120±5°C at a rate of 4 to 6°C / min, react for 1 to 1.5 hours, and post-treat to obtain a flame retardant.

[0017] Furthermore, in the flame retardant, the mass ratio of modified polysiloxane, modified isoprene and tetrabutyl titanate is 1:(0.3-0.4):(0.1-0.2).

[0018] Furthermore, in the flame retardant monomer, the mass ratio of 2-aminopyridine-5-boric acid pinacol ester, triethylamine, and vinylphosphonyl chloride is (4.5-5):1:1.4.

[0019] Furthermore, the raw materials of the modified polysiloxane include the following materials in parts by mass: 20 parts of hydrogen-containing polysiloxane, 3 to 5 parts of 3,7-dimethyl-1,6-octadiene, 12 to 15 parts of flame retardant monomers, 2 to 3 parts of 4-allyl catechol, 2 to 3 parts of borax, 0.05 to 0.08 parts of platinum catalysts, and 100 to 120 parts of tetrahydrofuran; the raw materials of the modified isoprene include the following materials in parts by mass: 30 parts of liquid isoprene, 4 to 6 parts of flame retardant monomers, 3 to 5 parts of 4-allyl catechol, 2 to 3 parts of borax, 0.05 to 0.1 parts of initiators, and 100 to 120 parts of xylene.

[0020] Furthermore, during the plasticating process, the temperature is controlled at 40-50°C, and the plasticating time is 3-6 minutes; during the banburying process, the temperature is controlled at 110-120°C, and the time is 1-2 minutes; during the open refining process, the temperature is controlled at 40-50°C and thinned 3-5 times; and the extrusion parking time is 24 hours.

[0021] Furthermore, during the vulcanization process, the first steam vulcanization is performed at 150±5°C for 15 to 40 minutes, the second steam vulcanization is performed at 170±5°C for 15 to 40 minutes, and the vulcanization is performed in a vulcanization box at 180±5°C; 200±5°C for 5 to 10 minutes.

[0022] Furthermore, a flame retardant rubber foam material is prepared by a method for preparing a halogen-free, sulfur-free and environmentally friendly flame retardant rubber foam material.

[0023] Compared with the prior art, the beneficial effects of the present application are as follows: in the scheme, methyl vinyl silicone rubber and natural rubber are mixed as a rubber matrix, and a flame retardant is introduced to enhance the flame retardancy and improve the compatibility of the rubber matrix; thereby improving the comprehensive performance of the rubber.

[0024] In the scheme, the amount of flame retardant introduced is too much. If conventional flame retardants are used, there will be compatibility problems, and methyl vinyl silicone rubber and natural rubber cannot be solved. Therefore, in the scheme, a composite flame retardant containing modified polysiloxane and modified isoprene segments is prepared; wherein, modified polysiloxane has good affinity with methyl vinyl silicone rubber, and it contains reactive segments, and modified isoprene has similar compatibility with natural rubber, so the flame retardant not only improves the flame retardancy after application, but also enhances the compatibility of the two rubbers. Among them, if a single modified polysiloxane is used as a flame retardant, there will be partial cross-linking, which will affect the uniformity of pores in the flame-retardant rubber foam material and reduce the mechanical properties; and if a single modified isoprene is used, the affinity with methyl vinyl silicone rubber is also poor, affecting the comprehensive performance. After the two are compounded with titanium, not only the overall flame retardancy is improved, but also the compatibility is enhanced. Among them, the ratio of the two needs to be limited. Due to the different chain segments, the overall mechanical properties and flame retardant properties will be affected.

[0025] Among them, the flame retardant monomer is prepared by using the amino group in 2-aminopyridine-5-boric acid pinacol ester and vinyl phosphonyl chloride. The reaction amount of 2-aminopyridine-5-boric acid pinacol ester is greater than the theoretical reaction amount. First, the reactivity is improved, and second, the grafting is improved, and the chlorine residue is inhibited, thereby ensuring the halogen-free nature of the flame retardant monomer. Since the flame retardant monomer contains nitrogen, boron, and phosphorus, it becomes a highly efficient flame retardant with vinyl. Vinyl can be grafted on hydrogen-containing polysiloxane and liquid isoprene through hydrosilylation and free radical reaction. On the other hand, the modified polysiloxane is also grafted with 3,7-dimethyl-1,6-octadiene and 4-allyl catechol segments; the terminal olefin group in 3,7-dimethyl-1,6-octadiene reacts with silicon hydrogen, and the other olefin group can increase the crosslinking of the modified polysiloxane with the rubber matrix; and the grafted 4-allyl catechol contains catechol groups that can crosslink with the catechol groups in the modified isoprene under the action of titanium ions to form a composite flame retardant; titanium ions further improve the flame retardant properties of the flame retardant. In this way, a flame retardant containing a flame retardant monomer with a specific structure, a silicon chain, and an isoprene segment was prepared.

[0026] The solution uses organic peroxide vulcanizers as additives, and uses metal-based accelerators to provide ionic bonds, which coordinate the three-stage vulcanization process to increase the uniformity of co-crosslinking, ionic crosslinking, and physical entanglement, thereby improving foaming uniformity and enhancing comprehensive performance. Compared with sulfur-containing vulcanizers and accelerators, the solution is more environmentally friendly. DETAILED DESCRIPTION

[0027] 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.

[0028] It should be noted that the parts involved in the embodiments are parts by mass; the purchase manufacturers of all raw materials involved in the present invention are not subject to any special restrictions, and exemplary examples include: the vinyl content in the methyl vinyl silicone rubber is 0.16 mol%, and the brand is 110-2; the brand of natural rubber is SVR-3L; the brand of plasticizer is Condis, and its alias is butyl benzyl phthalate; the organic peroxide vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; the metal-based accelerator is zinc dimethacrylate; the foaming agent is foaming agent H; the foaming aid is urea fat BK; the dispersant is zinc stearate; the model of the antioxidant is rubber antioxidant 402 0; the crosslinking agent is tri(2-acryloyloxyethyl) isocyanurate; the carbon black model is N880R; the hydrogen content of the hydrogen-containing polysiloxane is 1.6, and the brand is Hubei Xinsihai; the model of liquid isoprene is IR563; the content of effective substances in the platinum catalyst is 0.15%, and the brand is IOTA; the CAS number of vinylphosphonyl chloride is 1438-74-0, the CAS number of 3,7-dimethyl-1,6-octadiene is 2436-90-0, the CAS number of 4-allylcatechol is 1126-61-0, and the CAS number of 2-aminopyridine-5-boric acid pinacol ester is 827614-64-2, all of which are commercially available.

[0029] Preparation of flame retardant: Step 1: 20 parts of 2-aminopyridine-5-boric acid pinacol ester and 4 parts of triethylamine are added to 80 parts of 1,4-dioxane in sequence, stirred evenly, and a mixed solution of 1,4-dioxane containing vinyl phosphonyl chloride (containing 5.6 parts of vinyl phosphonyl chloride) is added, reacted at 45° C. for 8 hours, and post-treated to obtain a flame retardant monomer;

[0030] Step 2: 20 parts of hydrogen-containing polysiloxane, 4 parts of 3,7-dimethyl-1,6-octadiene, 14 parts of flame retardant monomer, 3 parts of 4-allylcatechol, 0.08 parts of platinum catalyst, and 2 parts of borax are sequentially added to 100 parts of tetrahydrofuran, reacted at 65° C. for 3 hours under a nitrogen atmosphere, and post-treated to obtain modified polysiloxane;

[0031] Step 3: 30 parts of liquid isoprene, 5 parts of flame retardant monomer, 5 parts of 4-allylcatechol, and 3 parts of borax are sequentially added to 100 parts of xylene, reacted at 70° C. under a nitrogen atmosphere, and an initiator solution (containing 0.05 parts of AIBN) is added, reacted for 8 hours, and post-treated to obtain modified isoprene;

[0032] Step 4: Add 10 parts of modified polysiloxane and 3.5 parts of modified isoprene to xylene, and add 0.01 parts of ammonia water; add 10wt% of a xylene mixed solution containing tetrabutyl titanate (containing 0.15 parts of tetrabutyl titanate) under stirring, and stir for 1 hour; heat to 80°C and react for 1.5 hours; then heat to 120°C at a rate of 5°C / min, react for 1 hour, post-treat to obtain a flame retardant, which is used in Examples 1 to 3.

[0033] Embodiment 1: A method for preparing a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material, comprising the following steps:

[0034] Step 1: 30 parts of methyl vinyl silicone rubber and 30 parts of natural rubber are respectively put on an open mill for plastication, the temperature of the open mill is controlled at 45°C, and plastication is performed for 5 minutes for standby use; the plasticized product and 40 parts of flame retardant, 30 parts of carbon black, 15 parts of plasticizer, 1.5 parts of metal-based accelerator, 2 parts of organic peroxide vulcanizer, 1 part of antioxidant, 1.5 parts of dispersant, 0.8 parts of crosslinking agent, 1.8 parts of foaming aid, and 6.5 parts of foaming agent are put into an internal mixer in sequence for internal mixing, and the temperature of the internal mixer is controlled at 110°C for internal mixing for 1 to 2 minutes; the refined material is put on an open mill for mixing, the temperature of the open mill is controlled at 45°C, and thinned 5 times; it is put into an extruder, and the specifications of the extruder are extruded according to the mold size and then parked for 24 hours for standby use, which is the basic material;

[0035] Step 2: Put the base material into the mold of the vulcanizer for vulcanization, the hot plate temperature of the vulcanizer is set at 150°C, the temperature is controlled by steam, and the first vulcanization time is 30 minutes; put the semi-finished product of the first vulcanization into the mold of the second vulcanization for vulcanization, the temperature is set at 170°C, the temperature is controlled by steam, and the time is 30 minutes; place the foamed board after the second vulcanization on the board rack and push it into the third vulcanization box, the temperature is set at 200°C, the time is 6 minutes, and the temperature is naturally cooled to obtain a flame retardant rubber foam material.

[0036] Embodiment 2: A method for preparing a halogen-free, sulfur-free, and environmentally friendly flame-retardant rubber foam material, comprising the following steps:

[0037] Step 1: 20 parts of methyl vinyl silicone rubber and 40 parts of natural rubber are respectively put on an open mill for plastication, the temperature of the open mill is controlled at 45°C, and plastication is performed for 5 minutes for standby use; the plasticized product and 40 parts of flame retardant, 28 parts of carbon black, 12 parts of plasticizer, 1.5 parts of metal-based accelerator, 2 parts of organic peroxide vulcanizer, 1 part of antioxidant, 1.5 parts of dispersant, 0.9 parts of crosslinking agent, 2 parts of foaming aid, 5.5 parts of foaming agent are put into an internal mixer in sequence for internal mixing, and the temperature of the internal mixer is controlled at 110°C for internal mixing for 1 to 2 minutes; the refined material is put on an open mill for mixing, the temperature of the open mill is controlled at 45°C, and thinned 5 times; it is put into an extruder, and the specifications of the extruder are extruded according to the size of the mold and then parked for 24 hours for standby use, which is the basic material;

[0038] Step 2: Put the base material into the mold of the vulcanizer for vulcanization, the hot plate temperature of the vulcanizer is set at 150°C, the temperature is controlled by steam, and the first vulcanization time is 30 minutes; put the semi-finished product of the first vulcanization into the mold of the second vulcanization for vulcanization, the temperature is set at 170°C, the temperature is controlled by steam, and the time is 30 minutes; place the foamed board after the second vulcanization on the board rack and push it into the third vulcanization box, the temperature is set at 200°C, the time is 6 minutes, and the temperature is naturally cooled to obtain a flame retardant rubber foam material.

[0039] Embodiment 3: A method for preparing a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material, comprising the following steps:

[0040] Step 1: 10 parts of methyl vinyl silicone rubber and 50 parts of natural rubber are respectively put on an open mill for plasticization, the temperature of the open mill is controlled at 45°C, and plasticization is performed for 5 minutes for standby use; the plasticized product and 38 parts of flame retardant, 28 parts of carbon black, 10 parts of plasticizer, 1.5 parts of metal-based accelerator, 2 parts of organic peroxide vulcanizer, 1 part of antioxidant, 1.5 parts of dispersant, 0.9 parts of crosslinking agent, 2 parts of foaming aid, 4.3 parts of foaming agent are put into an internal mixer in sequence for internal mixing, and the temperature of the internal mixer is controlled at 110°C for internal mixing for 1 to 2 minutes; the refined material is put on an open mill for mixing, the temperature of the open mill is controlled at 45°C, and thinned 5 times; it is put into an extruder, and the specifications of the extruder are extruded according to the size of the mold and then parked for 24 hours for standby use, which is the basic material;

[0041] Step 2: Put the base material into the mold of the vulcanizer for vulcanization, the hot plate temperature of the vulcanizer is set at 150°C, the temperature is controlled by steam, and the first vulcanization time is 30 minutes; put the semi-finished product of the first vulcanization into the mold of the second vulcanization for vulcanization, the temperature is set at 170°C, the temperature is controlled by steam, and the time is 30 minutes; place the foamed board after the second vulcanization on the board rack and push it into the third vulcanization box, the temperature is set at 200°C, the time is 6 minutes, and the temperature is naturally cooled to obtain a flame retardant rubber foam material.

[0042] Comparative Example 1: Introducing modified polysiloxane as a flame retardant, specifically as follows:

[0043] Preparation of flame retardant: Step 1: 20 parts of 2-aminopyridine-5-boric acid pinacol ester and 4 parts of triethylamine are added to 80 parts of 1,4-dioxane in sequence, stirred evenly, and a mixed solution of 1,4-dioxane containing vinyl phosphonyl chloride (containing 5.6 parts of vinyl phosphonyl chloride) is added, reacted at 45° C. for 8 hours, and post-treated to obtain a flame retardant monomer;

[0044] Step 2: 20 parts of hydrogen-containing polysiloxane, 4 parts of 3,7-dimethyl-1,6-octadiene, 14 parts of flame retardant monomer, 3 parts of 4-allylcatechol, 0.08 parts of platinum catalyst, and 2 parts of borax are added to 100 parts of tetrahydrofuran in sequence, reacted at 65° C. for 3 hours under a nitrogen atmosphere, and post-treated to obtain modified polysiloxane, which is used as the flame retardant in Comparative Example 1; the rest is the same as Example 1.

[0045] Comparative Example 2: Introducing modified isoprene as a flame retardant, specifically as follows:

[0046] Preparation of flame retardant: Step 1: 20 parts of 2-aminopyridine-5-boric acid pinacol ester and 4 parts of triethylamine are added to 80 parts of 1,4-dioxane in sequence, stirred evenly, and a mixed solution of 1,4-dioxane containing vinyl phosphonyl chloride (containing 5.6 parts of vinyl phosphonyl chloride) is added, reacted at 45° C. for 8 hours, and post-treated to obtain a flame retardant monomer;

[0047] Step 2: 30 parts of liquid isoprene, 5 parts of flame retardant monomer, 5 parts of 4-allylcatechol, and 3 parts of borax are added to 100 parts of xylene in sequence, reacted at 70°C under a nitrogen atmosphere, added with an initiator solution (containing 0.05 parts of AIBN), reacted for 8 hours, and post-treated to obtain modified isoprene; this is used as the flame retardant in Comparative Example 2; the rest is the same as Example 1.

[0048] Comparative Example 3: The ratio of modified polysiloxane and modified isoprene in the flame retardant was changed as follows:

[0049] Preparation of flame retardant: Step 1: 20 parts of 2-aminopyridine-5-boric acid pinacol ester and 4 parts of triethylamine are added to 80 parts of 1,4-dioxane in sequence, stirred evenly, and a mixed solution of 1,4-dioxane containing vinyl phosphonyl chloride (containing 5.6 parts of vinyl phosphonyl chloride) is added, reacted at 45° C. for 8 hours, and post-treated to obtain a flame retardant monomer;

[0050] Step 2: 20 parts of hydrogen-containing polysiloxane, 4 parts of 3,7-dimethyl-1,6-octadiene, 14 parts of flame retardant monomer, 3 parts of 4-allylcatechol, 0.08 parts of platinum catalyst, and 2 parts of borax are sequentially added to 100 parts of tetrahydrofuran, reacted at 65° C. for 3 hours under a nitrogen atmosphere, and post-treated to obtain modified polysiloxane;

[0051] Step 3: 30 parts of liquid isoprene, 5 parts of flame retardant monomer, 5 parts of 4-allylcatechol, and 3 parts of borax are sequentially added to 100 parts of xylene, reacted at 70° C. under a nitrogen atmosphere, and an initiator solution (containing 0.05 parts of AIBN) is added, reacted for 8 hours, and post-treated to obtain modified isoprene;

[0052] Step 4: Add 3.5 parts of modified polysiloxane and 10 parts of modified isoprene to xylene, and add 0.01 parts of ammonia water; add 10wt% of a xylene mixed solution containing tetrabutyl titanate (containing 0.15 parts of tetrabutyl titanate) under stirring, and stir for 1 hour; heat to 80°C and react for 1.5 hours; then heat to 120°C at a rate of 5°C / min, react for 1 hour, and post-treat to obtain a flame retardant; this is the flame retardant in Comparative Example 3; the rest is the same as Example 1.

[0053] Performance test: The flame retardant rubber foam materials prepared in the examples and comparative examples were tested for mechanical properties and flame retardant properties; (1) referring to the standard method of GB / T528, the flame retardant rubber foam materials were made into dumbbell-shaped specimens, and the tensile strength was tested at a tensile rate of 500 mm / min; (2) referring to the standard method of GB / T10707, the limiting oxygen index was tested; the obtained data are shown in the following table:

[0054]

[0055] Conclusion: It can be seen from the data in the above table that the flame retardant rubber foam material prepared in the present application has good mechanical properties on the basis of excellent flame retardant properties; at the same time, it can be seen from the comparative examples that the flame retardant prepared in the present application has increased compatibility on the basis of improving the flame retardant due to the compounding of modified polysiloxane and modified isoprene, thereby improving the uniformity of the material during the vulcanization and foaming process and increasing the mechanical properties. The ratio of the two needs to be limited because the changes in the chain segments and groups affect the comprehensive performance.

[0056] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a halogen-free, sulfur-free, and environmentally friendly flame-retardant rubber foam material, characterized in that: The process includes: Step 1: Methyl vinyl silicone rubber and natural rubber are plasticized separately, and the plasticized products are mixed with flame retardant, carbon black, plasticizer and additives, and then the products are subjected to internal mixing, open mixing, extrusion and parking in sequence to obtain a base material; Step 2: vulcanizing the base material, during the vulcanization process, the first steam vulcanization is performed at 150±5°C for 15-40 minutes, the second steam vulcanization is performed at 170±5°C for 15-40 minutes, and the vulcanization is performed in a vulcanization box at 180±5°C; 200±5°C for 5-10 minutes to obtain a flame retardant rubber foam material; The flame retardant rubber foam material comprises the following materials by weight: 10 to 40 parts of methyl vinyl silicone rubber, 20 to 50 parts of natural rubber, 38 to 42 parts of flame retardant, 25 to 30 parts of carbon black, 10 to 18 parts of plasticizer, and 11 to 17 parts of auxiliary agent; The preparation method of the flame retardant comprises the following steps: Step 1: 2-aminopyridine-5-boric acid pinacol ester and triethylamine are added to 1,4-dioxane in sequence, stirred evenly, and a mixed solution of 1,4-dioxane containing vinylphosphonyl chloride is added, reacted at 45±5°C for 6-8 hours, and post-treated to obtain a flame retardant monomer; Step 2: adding hydrogen-containing polysiloxane, 3,7-dimethyl-1,6-octadiene, flame retardant monomer, 4-allylcatechol, platinum catalyst and borax to tetrahydrofuran in sequence, reacting at 65±5° C. for 2-4 hours under nitrogen atmosphere, and post-treating to obtain modified polysiloxane; Step 3: liquid isoprene, flame retardant monomer, 4-allylcatechol, and borax are sequentially added to xylene, reacted at 70±5° C. under a nitrogen atmosphere, and an initiator solution is added to react for 6 to 10 hours, and post-treated to obtain modified isoprene; Step 4: Add modified polysiloxane and modified isoprene to xylene, and add ammonia water; add a xylene mixed solution containing tetrabutyl titanate under stirring, and stir for 1 to 2 hours; heat to 80±5°C and react for 1 to 1.5 hours; then heat to 120±5°C at a rate of 4 to 6°C / min, react for 1 to 1.5 hours, and post-treat to obtain a flame retardant; The model of the liquid isoprene is IR563.

2. The method for preparing a halogen-free, sulfur-free, environmentally friendly flame-retardant rubber foam material according to claim 1, characterized in that: The auxiliary agent includes the following materials in parts by weight: 1 to 2 parts of metal-based accelerator, 1.6 to 2.5 parts of organic peroxide vulcanizer, 1 to 1.5 parts of antioxidant, 1 to 1.5 parts of dispersant, 0.8 to 1 parts of cross-linking agent, 1.8 to 2 parts of foaming auxiliary agent, and 3.8 to 6.5 parts of foaming agent.

3. The method for preparing a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material according to claim 1, characterized in that: In the flame retardant, the mass ratio of modified polysiloxane, modified isoprene and tetrabutyl titanate is 1:(0.3-0.4):(0.1-0.2).

4. The method for preparing a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material according to claim 1, characterized in that: In the flame retardant monomer, the mass ratio of 2-aminopyridine-5-boric acid pinacol ester, triethylamine and vinylphosphonyl chloride is (4.5-5):1:1.

4.

5. The method for preparing a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material according to claim 1, characterized in that: The raw materials of the modified polysiloxane include the following materials in parts by mass: 20 parts of hydrogen-containing polysiloxane, 3 to 5 parts of 3,7-dimethyl-1,6-octadiene, 12 to 15 parts of flame retardant monomers, 2 to 3 parts of 4-allyl catechol, 2 to 3 parts of borax, 0.05 to 0.08 parts of platinum catalysts, and 100 to 120 parts of tetrahydrofuran; the raw materials of the modified isoprene include the following materials in parts by mass: 30 parts of liquid isoprene, 4 to 6 parts of flame retardant monomers, 3 to 5 parts of 4-allyl catechol, 2 to 3 parts of borax, 0.05 to 0.1 parts of initiators, and 100 to 120 parts of xylene.

6. The method for preparing a halogen-free, sulfur-free, environmentally friendly flame-retardant rubber foam material according to claim 1, characterized in that: During the plasticating process, the temperature is controlled at 40-50°C, and the plasticating time is 3-6 minutes; during the banburying process, the temperature is controlled at 110-120°C, and the time is 1-2 minutes; during the open refining process, the temperature is controlled at 40-50°C, and the thin pass is performed 3-5 times; the extrusion parking time is 24 hours.

7. The flame-retardant rubber foam material prepared according to the method for preparing a halogen-free, sulfur-free and environmentally friendly flame-retardant rubber foam material according to any one of claims 1 to 6.

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