Low-smoke and low-toxicity steel wire rope core flame-retardant conveying belt for coal mine and preparation method thereof
By introducing phosphorus-based flame retardants and carbon-forming flame retardants into the flame-retardant conveyor belt with steel wire rope core for coal mines, and modifying sepiolite to form hydrogen bonds and covalent bonds with rubber, the problems of high smoke and toxic gases during conveyor belt combustion are solved, tensile strength and wear resistance are improved, and a low-smoke and low-toxicity flame-retardant effect is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-27
- Publication Date
- 2026-03-31
AI Technical Summary
Existing steel wire rope core flame-retardant conveyor belts for coal mines produce a large amount of dense smoke and toxic gases when burning, which damages the mechanical properties of the rubber and makes it difficult to simultaneously meet the requirements of flame retardancy and low smoke and low toxicity.
By using phosphorus-based flame retardants, char-forming flame retardants, and wear-resistant fillers, and by modifying sepiolite to form hydrogen bonds and covalent bonds with rubber, the tensile strength is improved, and a dense char layer is formed during combustion to achieve efficient and low-smoke flame retardancy.
It significantly improves the tensile strength and wear resistance of the conveyor belt, reduces the generation of smoke and toxic gases during combustion, and meets the stringent low-smoke safety requirements in underground coal mines.
Smart Images
Figure CN121757519A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of conveyor belt technology, and particularly relates to a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines and its preparation method. Background Technology
[0002] Flame-retardant steel wire rope conveyor belts are the main equipment for transporting materials in underground coal mines. During ore mining, the large differences in material particle size and the high drop height create a huge impact on the conveyor belt, easily causing surface scratches or even tears. The risk of underground coal mine fires remains consistently high. Mine fires are a major threat to coal mine safety, mostly caused by spontaneous combustion of coal or fires on the conveyor belt. The vast majority of casualties in these fires stem from "secondary disasters": the large amounts of dense smoke, toxic gases, and highly corrosive fumes produced when the conveyor belt burns. This smoke drastically reduces visibility in escape routes, severely hindering evacuation and rescue operations; simultaneously, the released toxic gases such as hydrogen halides pose a direct threat to miners' lives. Furthermore, highly corrosive fumes can severely damage critical equipment such as underground monitoring, communication, and ventilation systems, causing the accident's impact to expand.
[0003] Currently, to meet the physical and flame-retardant performance requirements of standards, mainstream products still heavily rely on halogenated rubber and halogenated flame retardants in their cover rubber formulations, or use rubber combined with a large amount of halogenated-antimony flame-retardant synergistic systems. While this approach may meet conventional flame-retardant test standards, in the event of a fire, these halogenated materials will produce extremely high smoke density and large amounts of highly toxic and corrosive gases such as hydrogen halides. Furthermore, conventional halogen-free flame retardants require high filler volumes to meet flame-retardant standards, which often severely damages the mechanical properties of the rubber, leading to a decrease in tensile strength and abrasion resistance. Therefore, ensuring the stable presence of flame retardants in the matrix while simultaneously providing reinforcement is crucial for the development of high-performance halogen-free flame-retardant conveyor belts.
[0004] In summary, while ensuring the basic mechanical and flame-retardant properties of conveyor belts, how to fundamentally reduce the amount of smoke and the toxicity of flue gas during combustion has become an urgent problem to be solved in the field of coal mine safety production. Summary of the Invention
[0005] The primary objective of this invention is to provide a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines. The flame-retardant conveyor belt for coal mines provided by this invention incorporates phosphorus-based flame retardants, char-forming flame retardants, and wear-resistant fillers, thereby improving the conveyor belt's tensile strength, wear resistance, and tear resistance. Furthermore, it possesses excellent flame-retardant properties, meeting the extremely stringent low-smoke safety requirements of underground coal mines.
[0006] The second objective of this invention is to provide a method for preparing a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines. This method has a mature manufacturing process, strong operational feasibility, and can be mass-produced, showing promising application prospects in actual production.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines includes a cover rubber layer, which comprises the following raw materials in parts by weight: 60-70 parts of EPDM rubber, 40-50 parts of nitrile rubber, 25-35 parts of phosphorus-based flame retardant, 10-15 parts of reinforcing agent, 10-15 parts of plasticizer, 5-10 parts of vulcanizing agent, 5-10 parts of carbon-forming flame retardant, 5-8 parts of wear-resistant filler, 1.5-2 parts of catalyst, 5-7 parts of accelerator, 3-5 parts of antioxidant, and 5-10 parts of softener; The chemical structural formula of the phosphorus-based flame retardant is as follows: Furthermore, the preparation process of the phosphorus-based flame retardant is as follows: (1) Tris(dibenzylacetone)dipalladium, 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene and cis-1,2-dihydroxymethylethylene were added to a solvent, stirred until homogeneous, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added and heated to react. The reaction solution was concentrated and purified to obtain intermediate 1. (2) Add intermediate 1 to the solvent, then add m-chloroperoxybenzoic acid at 0°C, stir until homogeneous, and react at room temperature; purify to obtain intermediate 2; (3) Add 6-(hydroxymethyl)naphth-2-yl methacrylate, intermediate 2 and triphenylphosphine to the solvent, stir evenly, and add diisopropyl azobisisopropionate at 0°C under nitrogen atmosphere to carry out the reaction; concentrate and purify the reaction solution to obtain the product.
[0008] Further, in step (1), the ratio of tris(dibenzylacetone)dipalladium, 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene, cis-1,2-dihydroxymethylethylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and solvent is 0.1~0.3 mmol: 0.2~0.5 mmol: 5~6 mmol: 5 mmol: 20 mL; the solvent is anhydrous toluene; the reaction temperature is 90~100°C, and the time is 16~24 h.
[0009] Further, in step (2), the ratio of intermediate 1, m-chloroperoxybenzoic acid, and solvent is 6 mmol: 8~10 mmol: 20 mL; the solvent is acetonitrile; the reaction time is 16~24 h; in step (3), the ratio of 6-(hydroxymethyl)naphthyl-2-methylmethacrylate, intermediate 2, triphenylphosphine, diisopropyl azodiisopropionate, and solvent is 3.5~4.0 mmol: 3.0~3.5 mmol: 5.0~6.0 mmol: 5.5~6.5 mmol: 30 mL; the solvent is anhydrous toluene; the reaction is specifically: first react at 0°C for 1~3 h, then heat to room temperature and react for 16~24 h.
[0010] Furthermore, the preparation process of the wear-resistant filler is as follows: ethylene glycol monomethyl ether propionic acid, sepiolite, and aluminum chloride solution are added to anhydrous acetone for reaction; the reaction solution is centrifuged, washed, filtered, dried, and ground to obtain the filler.
[0011] Furthermore, the ratio of ethylene glycol monomethyl ether propionic acid, sepiolite, aluminum chloride solution, and anhydrous acetone is 0.5g:2~3g:18~20mL:30mL; the concentration of the aluminum chloride solution is 2.5wt%; and the reaction time is 6~12h.
[0012] Furthermore, the diameter of sepiolite ranges from 50 nm to 300 nm.
[0013] Further, the ethylene propylene diene monomer (EPDM) rubber has an ethylene content of 50%~60% and a Mooney viscosity of 40~50; the nitrile butadiene rubber has an acrylonitrile content of 34%~37% and a Mooney viscosity of 40~50; the reinforcing agent is carbon black N234; the plasticizer is stearic acid; the vulcanizing agent is sulfur; the carbon-forming flame retardant is pentaerythritol; the catalyst is trimethylenediamine; the accelerator is accelerator TMTD; the antioxidant is antioxidant NBC; and the softener is paraffin oil.
[0014] Furthermore, the steel wire rope core flame-retardant conveyor belt also includes a steel wire rope core and an intermediate rubber layer wrapped around the outside of the steel wire rope core, wherein the covering rubber layer is disposed outside the intermediate rubber layer; The intermediate adhesive layer comprises the following raw materials in parts by weight: 50-60 parts styrene-butadiene rubber, 10-20 parts natural rubber, 2-5 parts phenolic resin, 3-5 parts zinc oxide, 5-10 parts silica, 1-3 parts accelerator, 5-10 parts phosphorus flame retardant, 3-5 parts carbon-forming flame retardant, 1-3 parts antioxidant NBC, 1-3 parts crosslinking agent PDM, and 1-5 parts vulcanizing agent.
[0015] Furthermore, the accelerator is TMTD; the char-forming flame retardant is pentaerythritol; the antioxidant is NBC; the crosslinking agent is PDM; and the vulcanizing agent is sulfur. The chemical structural formula of the phosphorus-based flame retardant is as follows: .
[0016] The preparation method of the above-mentioned low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines includes the following preparation steps: S1. Weigh each raw material of the covering rubber layer according to the formula, and mix them to obtain the covering rubber layer; S2. Weigh the raw materials for the intermediate rubber layer according to the proportions, and mix them to obtain the intermediate rubber layer; S3. Wrap an intermediate rubber layer around the outside of the wire rope core, and then attach a cover rubber layer over the intermediate rubber layer. Press the rubber layer to form a strip blank, and vulcanize it to obtain the final product.
[0017] Compared with the prior art, the main advantages of the present invention are as follows: 1. This invention provides a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines. The conveyor belt components incorporate a phosphorus-based flame retardant, wear-resistant filler, and a char-forming flame retardant. The phosphorus-based flame retardant of this invention contains a triple structure of vulcanizable double bonds, epoxy coupling, and phosphorus-based flame retardancy, exhibiting unique characteristics in EPDM / nitrile rubber blends: the methacrylate double bonds of the phosphorus-based flame retardant can participate in sulfur crosslinking, increasing the effective crosslinking density and improving tensile strength; the hydroxyl / ether bonds of the phosphorus-based flame retardant interact with nitrile rubber and charcoal... The polar groups on the surface of black or sepiolite form hydrogen bonds and even covalent bonds, firmly anchoring them to the polar phase; at the other end, the aromatic naphthalene ring and ester group generate van der Waals affinity with the non-polar ethylene-propylene segment of EPDM rubber, achieving stable association and improving tensile strength; when heated, the DOPO skeleton releases PO· free radicals to inhibit the combustion chain and catalyzes the formation of a dense, expanded char layer, achieving high-efficiency, low-smoke flame retardancy. In synergy with char-forming flame retardants, it can further strengthen the char layer structure and significantly improve flame retardant performance.
[0018] 2. The wear-resistant filler of the present invention modifies sepiolite by esterification of the silicon / magnesium hydroxyl groups on the surface of sepiolite with the carboxyl groups of ethylene glycol monomethyl ether propionic acid. Flexible external chains containing ether bonds can be grafted onto the particle surface, which significantly reduces hydrophilicity and inhibits agglomeration. The ether bonds have good affinity with the ester groups in phosphorus-based flame retardants and the EPDM / nitrile rubber segments, so that the modified sepiolite is evenly dispersed in the matrix and forms a hard micro-region-elastic network synergistic structure with carbon black, thereby further improving the wear resistance of the composite material.
[0019] 3. This invention also provides a method for preparing a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines. This method has a mature preparation process, strong operational feasibility, and can be mass-produced, showing good application prospects in actual production. Attached Figure Description
[0020] Figure 1 This is an electron microscope image of the wear-resistant filler obtained in Example 1 of the present invention. Detailed Implementation
[0021] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels.
[0022] The ethylene propylene diene monomer (EPDM) rubber of this invention has an ethylene content of 50%~60% and a Mooney viscosity of 40~50; the acrylonitrile butadiene rubber (NBR) has an acrylonitrile content of 34%~37% and a Mooney viscosity of 40~50; the styrene-butadiene rubber (SBR) is SBR 1502; the natural rubber is the No. 1 standard rubber of Hainan Natural Rubber Industry Group Co., Ltd.; the phenolic resin is a thermoplastic phenolic resin with a number average molecular weight range of 500-1900 Da; the silica is fumed silica with a particle size of 200 nm; and the sepiolite has a diameter of 50 nm-300 nm.
[0023] Example 1 A low-smoke, low-toxicity flame-retardant conveyor belt for coal mines with steel wire rope core includes a steel wire rope core, an intermediate rubber layer wrapped around the steel wire rope core, and a cover rubber layer disposed outside the intermediate rubber layer. The covering layer comprises the following raw materials in parts by weight: 65 parts EPDM rubber, 45 parts nitrile rubber, 30 parts phosphorus flame retardant, 12 parts reinforcing agent (carbon black N234), 12 parts plasticizer (stearic acid), 8 parts vulcanizing agent (sulfur), 8 parts carbon-forming flame retardant (pentaerythritol), 6 parts wear-resistant filler, 1.8 parts catalyst (trimethylenediamine), 6 parts accelerator (accelerator TMTD), 4 parts antioxidant (antioxidant NBC), and 8 parts softener (paraffin oil). The intermediate rubber layer comprises the following raw materials in parts by weight: 55 parts styrene-butadiene rubber 1502, 15 parts natural rubber, 3 parts phenolic resin, 4 parts zinc oxide, 8 parts silica, 2 parts accelerator (accelerator TMTD), 8 parts phosphorus flame retardant, 4 parts carbon-forming flame retardant (pentaerythritol), 2 parts antioxidant (antioxidant NBC), 2 parts crosslinking agent PDM, and 3 parts vulcanizing agent (sulfur). The preparation process of the phosphorus-based flame retardant is as follows: (1) Under a nitrogen atmosphere, tris(dibenzylacetone)dipalladium, 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene) and cis-1,2-dihydroxymethylethylene were added to anhydrous toluene. After stirring evenly, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, wherein the ratio of tris(dibenzylacetone)dipalladium, 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene), cis-1,2-dihydroxymethylethylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and anhydrous toluene was 0.2 mmol:0.3 mmol:5.5 mmol:5 mmol:20 mL. The reaction was heated at 95°C for 20 h. The reaction solution was concentrated and then purified by silica gel column chromatography (petroleum ether / ethyl acetate = 90:10) to obtain intermediate 1. 1 H NMR (C 16 H 15 O4P, 400 MHz, DMSO-d6) δ 8.03 (dd, 1H), 7.77 (dd, 1H),7.52-7.31 (m, 6H), 5.87-5.85 (m, 2H), 5.03 (s, 1H), 4.57-4.55 (m, 2H), 4.18(dd, 2H); HRMS(ESI) calcd for [M+H] + 303.07, found 303.07.
[0024] (2) Under a nitrogen atmosphere, intermediate 1 was added to acetonitrile, and then m-chloroperoxybenzoic acid was added at 0°C. The ratio of intermediate 1, m-chloroperoxybenzoic acid and acetonitrile was 6 mmol: 9 mmol: 20 mL. The mixture was stirred evenly and heated to room temperature for 20 h. The reaction was quenched with 10 wt% sodium thiosulfate aqueous solution, and the aqueous phase was extracted with ethyl acetate. The organic phase was dried with anhydrous sodium sulfate, concentrated and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 85:15) to obtain intermediate 2. 1 H NMR (C 16 H 15 O5P, 400 MHz, DMSO-d6) δ 8.03 (dd, 1H), 7.77 (dd, 1H),7.52-7.31 (m, 6H), 4.93 (s, 1H), 4.27-4.05 (m, 2H), 3.57-3.50 (m, 2H), 2.45-2.43 (m, 2H); HRMS(ESI) calcd for [M+H] + 319.07, found 319.07.
[0025] (3) Add 6-(hydroxymethyl)naphth-2-yl methacrylate, intermediate 2 and triphenylphosphine to anhydrous toluene, stir evenly, cool the above mixture to 0°C, place it under a nitrogen atmosphere, add diisopropyl azodiisopropionate dropwise, react at 0°C for 2 h, and then heat to room temperature for 20 h; wherein the ratio of 6-(hydroxymethyl)naphth-2-yl methacrylate, intermediate 2, triphenylphosphine, diisopropyl azodiisopropionate and anhydrous toluene is 3.8 mmol: 3.2 mmol: 5.5 mmol: 6 mmol: 30 mL; concentrate the reaction solution, and then purify it by silica gel column chromatography (petroleum ether / ethyl acetate = 90:10) to obtain the phosphorus flame retardant.
[0026] 1 H NMR (C 31 H 27 O7P, 400 MHz, DMSO-d6) δ 8.03 (dd, 1H), 7.85 (dd, 1H),7.77-7.70 (m, 2H), 7.62 (t, 1H), 7.51-7.32 (m, 8H), 7.07 (dd, 1H), HRMS(ESI) calcd for [M+H] + 543.15, found 543.16.
[0027] The preparation process of the wear-resistant filler is as follows: ethylene glycol monomethyl ether propionic acid, sepiolite, and 2.5 wt% aluminum chloride solution are added to anhydrous acetone; the ratio of ethylene glycol monomethyl ether propionic acid, sepiolite, aluminum chloride solution, and anhydrous acetone is 0.5 g: 2.5 g: 20 mL: 30 mL; the reaction mixture is stirred at room temperature for 10 h; the reaction solution is centrifuged, washed with anhydrous ethanol, filtered, dried, and ground to obtain the final product. The electron micrograph of the wear-resistant filler is shown below. Figure 1 As shown.
[0028] A method for preparing a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines includes the following preparation steps: S1. Mix EPDM rubber, nitrile rubber, carbon-based flame retardant, and phosphorus-based flame retardant at 80℃ and 0.35MPa for 3.5min. Then add accelerator, antioxidant, plasticizer, wear-resistant filler, reinforcing agent, and softener and mix at 95℃ and 0.35MPa for 4.5min. After extruding the rubber at 130℃ and cooling, mix vulcanizing agent and catalyst at 85℃ and 0.35MPa for 2.5min to obtain the compound rubber. Press the compound rubber into sheets using a two-roll mill to obtain the cover rubber layer. S2. Mix styrene-butadiene rubber, natural rubber, phenolic resin, zinc oxide, antioxidant, and accelerator evenly, and knead at 80℃ and 0.35MPa for 3.5min; then add silica, phosphorus flame retardant, and carbon-based flame retardant, and knead at 95℃ and 0.35MPa for 6min; finally add crosslinking agent and vulcanizing agent, and knead at 85℃ and 0.35MPa for 2.5min; then press the mixture into sheets using a two-roll mill to obtain the intermediate rubber layer. S3. Wrap an intermediate rubber layer around the outside of the wire rope core, and then attach the covering rubber layer to the outside of the intermediate rubber layer. Press the material to form a strip blank, and vulcanize it at 145°C for 35 minutes to obtain the final product.
[0029] Example 2 A low-smoke, low-toxicity flame-retardant conveyor belt for coal mines with steel wire rope core includes a steel wire rope core, an intermediate rubber layer wrapped around the steel wire rope core, and a cover rubber layer disposed outside the intermediate rubber layer. The covering layer comprises the following raw materials in parts by weight: 60 parts EPDM rubber, 40 parts nitrile rubber, 25 parts phosphorus flame retardant, 10 parts reinforcing agent (carbon black N234), 10 parts plasticizer (stearic acid), 5 parts vulcanizing agent (sulfur), 5 parts carbon-forming flame retardant (pentaerythritol), 5 parts wear-resistant filler, 1.5 parts catalyst (trimethylenediamine), 5 parts accelerator (accelerator TMTD), 3 parts antioxidant (antioxidant NBC), and 5 parts softener (paraffin oil). The intermediate rubber layer comprises the following raw materials in parts by weight: 50 parts styrene-butadiene rubber 1502, 10 parts natural rubber, 2 parts phenolic resin, 3 parts zinc oxide, 5 parts silica, 1 part accelerator (accelerator TMTD), 5 parts phosphorus flame retardant, 3 parts carbon-forming flame retardant (pentaerythritol), 1 part antioxidant (antioxidant NBC), 1 part crosslinking agent PDM, and 1 part vulcanizing agent (sulfur). The preparation process of the phosphorus-based flame retardant is as follows: (1) Under a nitrogen atmosphere, tris(dibenzylacetone)dipalladium, 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene) and cis-1,2-dihydroxymethylethylene were added to anhydrous toluene. After stirring evenly, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, wherein the ratio of tris(dibenzylacetone)dipalladium, 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene), cis-1,2-dihydroxymethylethylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and anhydrous toluene was 0.1 mmol:0.2 mmol:5 mmol:5 mmol:20 mL; the reaction was heated at 90°C for 24 h; the reaction solution was concentrated and then purified by silica gel column chromatography (petroleum ether / ethyl acetate = 90:10) to obtain intermediate 1; intermediate 1 1 The HNMR and HRMS (ESI) characterization results are the same as in Example 1.
[0030] (2) Under a nitrogen atmosphere, intermediate 1 was added to acetonitrile, and then m-chloroperoxybenzoic acid was added at 0°C, wherein the ratio of intermediate 1, m-chloroperoxybenzoic acid, and acetonitrile was 6 mmol: 8 mmol: 20 mL; the mixture was stirred evenly and heated to room temperature for 16 h; the reaction was quenched with 10 wt% sodium thiosulfate aqueous solution, and the aqueous phase was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 85:15) to obtain intermediate 2; intermediate 2 1 The HNMR and HRMS (ESI) characterization results are the same as in Example 1.
[0031] (3) 6-(hydroxymethyl)naphthyl-2-yl methacrylate, intermediate 2, and triphenylphosphine were added to anhydrous toluene and stirred until homogeneous. The mixture was cooled to 0°C and placed under a nitrogen atmosphere. Diisopropyl azodiisopropionate was added dropwise. The reaction was first carried out at 0°C for 1 hour, and then heated to room temperature for 24 hours. The ratio of 6-(hydroxymethyl)naphthyl-2-yl methacrylate, intermediate 2, triphenylphosphine, diisopropyl azodiisopropionate, and anhydrous toluene was 3.5 mmol: 3.0 mmol: 5.0 mmol: 5.5 mmol: 30 mL. The reaction solution was concentrated and then purified by silica gel column chromatography (petroleum ether / ethyl acetate = 90:10) to obtain the phosphorus-based flame retardant. 1 The HNMR and HRMS (ESI) characterization results are the same as in Example 1.
[0032] The preparation process of the wear-resistant filler is as follows: ethylene glycol monomethyl ether propionic acid, sepiolite, and 2.5 wt% aluminum chloride solution are added to anhydrous acetone; wherein the ratio of ethylene glycol monomethyl ether propionic acid, sepiolite, aluminum chloride solution and anhydrous acetone is 0.5 g: 2 g: 18 mL: 30 mL; the reaction is stirred at room temperature for 6 h; the reaction solution is centrifuged, washed with anhydrous ethanol, filtered, dried and ground to obtain the filler.
[0033] A method for preparing a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines includes the following preparation steps: S1. Mix EPDM rubber, nitrile rubber, carbon-forming flame retardant and phosphorus-based flame retardant at 85℃ and 0.35MPa for 3 minutes. Then add accelerator, antioxidant, plasticizer, wear-resistant filler, reinforcing agent and softener and mix at 98℃ and 0.35MPa for 4 minutes. After extruding the rubber at 125℃ and cooling, mix vulcanizing agent and catalyst at 90℃ and 0.35MPa for 2.5 minutes to obtain the compound rubber. Press the compound rubber into sheets through a two-roll mill to obtain the cover rubber layer. S2. Mix styrene-butadiene rubber, natural rubber, phenolic resin, zinc oxide, antioxidant, and accelerator evenly, and knead at 85℃ and 0.35MPa for 3.5 minutes; then add silica, phosphorus flame retardant, and carbon-based flame retardant, and knead at 90℃ and 0.35MPa for 7 minutes; finally add crosslinking agent and vulcanizing agent, and knead at 92℃ and 0.35MPa for 3 minutes. Then press the mixture into sheets using a two-roll mill to obtain the intermediate rubber layer. S3. Wrap an intermediate rubber layer around the outside of the wire rope core, and then attach the covering rubber layer to the outside of the intermediate rubber layer. Press the material to form a strip blank, and vulcanize it at 150°C for 30 minutes to obtain the final product.
[0034] Example 3 A low-smoke, low-toxicity flame-retardant conveyor belt for coal mines with steel wire rope core includes a steel wire rope core, an intermediate rubber layer wrapped around the steel wire rope core, and a cover rubber layer disposed outside the intermediate rubber layer. The covering layer comprises the following raw materials in parts by weight: 70 parts EPDM rubber, 50 parts nitrile rubber, 35 parts phosphorus flame retardant, 15 parts reinforcing agent (carbon black N234), 15 parts plasticizer (stearic acid), 10 parts vulcanizing agent (sulfur), 10 parts carbon-forming flame retardant (pentaerythritol), 8 parts wear-resistant filler, 2 parts catalyst (trimethylenediamine), 7 parts accelerator (accelerator TMTD), 5 parts antioxidant (antioxidant NBC), and 10 parts softener (paraffin oil). The intermediate rubber layer comprises the following raw materials in parts by weight: 60 parts of styrene-butadiene rubber 1502, 20 parts of natural rubber, 5 parts of phenolic resin, 5 parts of zinc oxide, 10 parts of silica, 3 parts of accelerator (accelerator TMTD), 10 parts of phosphorus flame retardant, 5 parts of carbon-forming flame retardant (pentaerythritol), 3 parts of antioxidant (antioxidant NBC), 3 parts of crosslinking agent PDM, and 5 parts of vulcanizing agent (sulfur). The preparation process of the phosphorus-based flame retardant is as follows: (1) Under a nitrogen atmosphere, tris(dibenzylacetone)dipalladium, 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene) and cis-1,2-dihydroxymethylethylene were added to anhydrous toluene. After stirring evenly, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, wherein the ratio of tris(dibenzylacetone)dipalladium, 4,5-bis(diphenylphosphine-9,9-dimethyloxanthracene), cis-1,2-dihydroxymethylethylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and anhydrous toluene was 0.3 mmol:0.5 mmol:6 mmol:5 mmol:20 mL; the reaction was heated at 100°C for 16 h; the reaction solution was concentrated and then purified by silica gel column chromatography (petroleum ether / ethyl acetate = 90:10) to obtain intermediate 1; intermediate 1 1 The HNMR and HRMS (ESI) characterization results are the same as in Example 1.
[0035] (2) Under a nitrogen atmosphere, intermediate 1 was added to acetonitrile, and then m-chloroperoxybenzoic acid was added at 0°C, wherein the ratio of intermediate 1, m-chloroperoxybenzoic acid, and acetonitrile was 6 mmol: 10 mmol: 20 mL; the mixture was stirred evenly and heated to room temperature for 24 h; the reaction was quenched with 10 wt% sodium thiosulfate aqueous solution, and the aqueous phase was extracted with ethyl acetate. The organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 85:15) to obtain intermediate 2; intermediate 2... 1 The HNMR and HRMS (ESI) characterization results are the same as in Example 1.
[0036] (3) Add 6-(hydroxymethyl)naphthyl-2-yl methacrylate, intermediate 2, and triphenylphosphine to anhydrous toluene, stir until homogeneous, cool the mixture to 0°C, place it under a nitrogen atmosphere, and add diisopropyl azodiisopropionate dropwise. React at 0°C for 3 hours, then raise the temperature to room temperature and react for 16 hours. The ratio of 6-(hydroxymethyl)naphthyl-2-yl methacrylate, intermediate 2, triphenylphosphine, diisopropyl azodiisopropionate, and anhydrous toluene is 4.0 mmol: 3.5 mmol: 6.0 mmol: 6.5 mmol: 30 mL. Concentrate the reaction solution and then purify it by silica gel column chromatography (petroleum ether / ethyl acetate = 90:10) to obtain the phosphorus-based flame retardant. The phosphorus-based flame retardant... 1 The HNMR and HRMS (ESI) characterization results are the same as in Example 1.
[0037] The preparation process of the wear-resistant filler is as follows: ethylene glycol monomethyl ether propionic acid, sepiolite, and 2.5 wt% aluminum chloride solution are added to anhydrous acetone; wherein the ratio of ethylene glycol monomethyl ether propionic acid, sepiolite, aluminum chloride solution and anhydrous acetone is 0.5 g: 3 g: 20 mL: 30 mL; the reaction is stirred at room temperature for 12 h; the reaction solution is centrifuged, washed with anhydrous ethanol, filtered, dried and ground to obtain the filler.
[0038] A method for preparing a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines includes the following preparation steps: S1. Mix EPDM rubber, nitrile rubber, carbon-based flame retardant and phosphorus-based flame retardant at 85℃ and 0.35MPa for 4 minutes. Then add accelerator, antioxidant, plasticizer, wear-resistant filler, reinforcing agent and softener and mix at 95℃ and 0.35MPa for 5 minutes. After extruding the rubber at 135℃ and cooling, mix vulcanizing agent and catalyst at 90℃ and 0.35MPa for 3 minutes to obtain the compound rubber. Press the compound rubber into sheets through a two-roll mill to obtain the cover rubber layer. S2. Mix styrene-butadiene rubber, natural rubber, phenolic resin, zinc oxide, antioxidant, and accelerator evenly, and knead at 85℃ and 0.35MPa for 3.5 minutes; then add silica, phosphorus flame retardant, and carbon-based flame retardant, and knead at 100℃ and 0.35MPa for 5 minutes; finally add crosslinking agent and vulcanizing agent, and knead at 92℃ and 0.35MPa for 3 minutes. Then press the mixture into sheets using a two-roll mill to obtain the intermediate rubber layer. S3. Wrap an intermediate rubber layer around the outside of the wire rope core, and then attach the covering rubber layer to the outside of the intermediate rubber layer. Press the material to form a strip blank, and vulcanize it at 140°C for 40 minutes to obtain the final product.
[0039] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that the phosphorus-based flame retardant is replaced with DOPO, and everything else is the same as Example 1.
[0040] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that the wear-resistant filler is replaced with sepiolite, and everything else is the same as Example 1.
[0041] Experimental Example To investigate the performance of the flame-retardant conveyor belts obtained in Examples 1-3 and Comparative Examples 1-2 of the present invention, the following tests were conducted: 1. The flame retardant properties, tensile strength, abrasion resistance, and tear strength are all measured in accordance with the standard MT / T668-2019 "Flame-retardant Conveyor Belt with Steel Wire Rope Core for Coal Mines".
[0042] 2. Smoke density was tested according to GB / T8323.2-2008 "Plastic Smoke Generation Part 2: Test Method for Determination of Smoke Density by Single Chamber Method". The test mode was 25kW / m³. 2 Calculate the specific optical density value Ds4 at 4 minutes, based on irradiance and flameless combustion.
[0043] 3. The toxicity index was implemented according to the standard EN45545.2; the gas concentration was collected at the 4th minute, and the CIT4 value was calculated. The above test results are shown in Table 1.
[0044] Table 1 As shown in Table 1, the flame-retardant performance, tensile strength, tear strength, abrasion resistance, smoke density, and toxicity index of the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belts for coal mines obtained in Examples 1-3 of this invention are all superior to those in Comparative Examples 1-2. Compared to Example 1, Comparative Example 1, which replaced the phosphorus-based flame retardant with DOPO, showed a significant decrease in tensile strength and tear strength, a decrease in the efficiency of the flame-retardant system, and a naturally longer burning time. These results indicate that the key to the improved mechanical properties and abrasion resistance of the phosphorus-based flame retardant of this invention is that DOPO, being unmodified, lacks the functional groups such as methacrylate double bonds and ether bonds found in phosphorus-based flame retardants, and to some extent, damages the network structure of the rubber, leading to a decrease in strength. Furthermore, the phosphorus-based flame retardant of this invention can improve the flame-retardant performance of the material, achieving efficient and low-smoke flame retardancy; and it can work together with char-forming flame retardants to strengthen the char layer structure, reducing the generation of smoke and toxic gases during combustion, enabling the conveyor belt obtained by this invention to meet the extremely stringent low-smoke safety requirements of underground coal mines.
[0045] In Comparative Example 2, replacing the wear-resistant filler with sepiolite significantly increased the wear of the conveyor belt, indicating that after modification, sepiolite can inhibit its own agglomeration, has good affinity with EPDM / nitrile rubber, and can form a hard micro-region-elastic network synergistic structure with carbon black, thereby improving its wear resistance.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.
Claims
1. A low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines, characterized in that, The product includes a cover layer comprising the following raw materials in parts by weight: 60-70 parts of EPDM rubber, 40-50 parts of nitrile rubber, 25-35 parts of phosphorus-based flame retardant, 10-15 parts of reinforcing agent, 10-15 parts of plasticizer, 5-10 parts of vulcanizing agent, 5-10 parts of char-forming flame retardant, 5-8 parts of wear-resistant filler, 1.5-2 parts of catalyst, 5-7 parts of accelerator, 3-5 parts of antioxidant, and 5-10 parts of softener. The chemical structural formula of the phosphorus-based flame retardant is as follows: .
2. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 1, characterized in that, The preparation process of the phosphorus-based flame retardant is as follows: (1) Tris(dibenzylacetone)dipalladium, 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene and cis-1,2-dihydroxymethylethylene were added to a solvent, stirred until homogeneous, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added and heated to react. The reaction solution was concentrated and purified to obtain intermediate 1. (2) Add intermediate 1 to the solvent, then add m-chloroperoxybenzoic acid at 0°C, stir evenly and react at room temperature; purify to obtain intermediate 2; (3) Add 6-(hydroxymethyl)naphth-2-yl methacrylate, intermediate 2 and triphenylphosphine to the solvent, stir evenly, and add diisopropyl azobisisopropionate at 0°C under nitrogen atmosphere to carry out the reaction; concentrate and purify the reaction solution to obtain the product.
3. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 2, characterized in that, In step (1), the ratio of tris(dibenzylacetone)palladium, 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene, cis-1,2-dihydroxymethylethylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and solvent is 0.1~0.3 mmol: 0.2~0.5 mmol: 5~6 mmol: 5 mmol: 20 mL; the solvent is anhydrous toluene; the reaction temperature is 90~100°C and the time is 16~24 h.
4. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 2, characterized in that, In step (2), the ratio of intermediate 1, m-chloroperoxybenzoic acid, and solvent is 6 mmol: 8~10 mmol: 20 mL; the solvent is acetonitrile; the reaction time is 16~24 h; in step (3), the ratio of 6-(hydroxymethyl)naphthyl-2-methylmethacrylate, intermediate 2, triphenylphosphine, diisopropyl azodiisopropionate, and solvent is 3.5~4.0 mmol: 3.0~3.5 mmol: 5.0~6.0 mmol: 5.5~6.5 mmol: 30 mL; the solvent is anhydrous toluene; the reaction is specifically carried out as follows: first react at 0°C for 1~3 h, then heat to room temperature and react for 16~24 h.
5. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 1, characterized in that, The preparation process of the wear-resistant filler is as follows: ethylene glycol monomethyl ether propionic acid, sepiolite, and aluminum chloride solution are added to anhydrous acetone for reaction; the reaction solution is centrifuged, washed, filtered, dried, and ground to obtain the filler.
6. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 5, characterized in that, The ratio of ethylene glycol monomethyl ether propionic acid, sepiolite, aluminum chloride solution, and anhydrous acetone is 0.5g:2~3g:18~20mL:30mL; the concentration of the aluminum chloride solution is 2.5wt%; and the reaction time is 6~12h.
7. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 1, characterized in that, The reinforcing agent is carbon black N234; the plasticizer is stearic acid; the vulcanizing agent is sulfur; the carbon-forming flame retardant is pentaerythritol; the catalyst is trimethylenediamine; the accelerator is accelerator TMTD; the antioxidant is antioxidant NBC; and the softener is paraffin oil.
8. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 1, characterized in that, The steel wire rope core flame-retardant conveyor belt also includes a steel wire rope core and an intermediate rubber layer wrapped around the steel wire rope core, with the covering rubber layer disposed outside the intermediate rubber layer; The intermediate adhesive layer comprises the following raw materials in parts by weight: 50-60 parts styrene-butadiene rubber, 10-20 parts natural rubber, 2-5 parts phenolic resin, 3-5 parts zinc oxide, 5-10 parts silica, 1-3 parts accelerator, 5-10 parts phosphorus flame retardant, 3-5 parts carbon-forming flame retardant, 1-3 parts antioxidant, 1-3 parts crosslinking agent, and 1-5 parts vulcanizing agent.
9. The method for preparing the low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to claim 8, characterized in that, The accelerator is TMTD; the char-forming flame retardant is pentaerythritol; the antioxidant is NBC; the crosslinking agent is PDM; and the vulcanizing agent is sulfur. The chemical structural formula of the phosphorus-based flame retardant is as follows: .
10. The method for preparing a low-smoke, low-toxicity steel wire rope core flame-retardant conveyor belt for coal mines according to any one of claims 1-9, characterized in that, The preparation steps include the following: S1. Weigh each raw material of the covering rubber layer according to the formula, and mix them to obtain the covering rubber layer; S2. Weigh the raw materials for the intermediate rubber layer according to the proportions, and mix them to obtain the intermediate rubber layer; S3. Wrap an intermediate rubber layer around the outside of the wire rope core, and then attach a cover rubber layer over the intermediate rubber layer. Press the rubber layer to form a strip blank, and vulcanize it to obtain the final product.