Steel cord core fire resistant conveyor belt and method of making same

Abstract

The present application belongs to the technical field of rubber conveyor belt, and particularly relates to a steel cord core flame-retardant conveyor belt and a preparation method thereof. The upper and lower cover rubber layers of the steel cord core flame-retardant conveyor belt are independently prepared from the following raw materials in parts by weight: butadiene styrene rubber 55-70 parts, butadiene rubber 20-30 parts, natural rubber 5-15 parts, allylized flaky boehmite 35-45 parts, sub-micron zinc borate 8-12 parts, modified flame retardant 4-8 parts, microcapsule red phosphorus 3-4 parts, antimony trioxide 2-4 parts, reinforcing filler 30-40 parts, silane coupling agent 1.5-2.8 parts, flame-retardant lubricant 6-10 parts, chlorinated paraffin 3-6 parts, vulcanization activator 4-7 parts, antioxidant 2-4 parts, accelerator 1.5-2.5 parts, and sulfur 1.8-2.5 parts. The conveyor belt prepared by the present application has high tensile strength, wear resistance and excellent flame-retardant performance.

Description

Technical Field

[0001] This invention belongs to the field of rubber conveyor belt technology, specifically relating to a steel wire rope core flame-retardant conveyor belt and its preparation method. Background Technology

[0002] Flame-retardant steel cord conveyor belts are mainly composed of a steel cord skeleton, a core rubber layer, and upper and lower cover rubber layers. They are indispensable material conveying equipment in coal mines, tunnel projects, ports, and other scenarios. Their core performance requirements include high strength, high wear resistance, excellent flame retardant properties, and low smoke and low toxicity. Among these, balancing flame retardant properties and mechanical properties is the technical challenge of this type of product.

[0003] Currently, the industry is gradually moving towards low-smoke, halogen-free, and highly efficient flame-retardant technologies. Existing solutions generally use CR / BR, SBR / BR / NR, CR / SBR / CPE, etc., with adhesives as the matrix, and achieve flame-retardant performance by introducing inorganic flame-retardant systems. For example, Chinese patent application CN106987035A discloses a steel cord core flame-retardant conveyor belt cover adhesive, comprising 20-170 parts of a flame-retardant system; Chinese patent application CN108841057A discloses a steel cord core flame-retardant conveyor belt and its preparation method, wherein the amount of solid flame retardant is 50-90 parts. While these existing technologies can improve the flame-retardant performance of conveyor belts to some extent, they still have some shortcomings in practical use.

[0004] Firstly, inorganic flame retardants are mostly micron-sized and rich in hydroxyl and polar oxygen groups on their surface. They have poor wettability with the non-polar styrene-butadiene rubber matrix and are difficult to disperse during high-shear mixing. They eventually aggregate in the matrix phase, which disrupts the continuity of the rubber crosslinking network and easily reduces the tensile strength and wear resistance of the conveyor belt. Secondly, the inorganic particles and the rubber matrix are mostly physically interlocked. Under the cyclic shear stress of particle impact and roller friction, the filler-matrix interface becomes the preferred path for crack initiation and propagation, resulting in local peeling, exposure of flame retardant dust, and a decline in mechanical properties and flame retardant performance of the conveyor belt after long-term use.

[0005] Therefore, there is a need to develop a low-smoke, halogen-free, high-flame-retardant conveyor belt with good filler-matrix compatibility and stable process. Summary of the Invention

[0006] Existing steel wire rope core flame-retardant conveyor belts have technical problems such as poor compatibility of fillers and difficulty in achieving both flame retardancy and mechanical properties. To solve the above technical problems, this invention provides a steel wire rope core flame-retardant conveyor belt and its preparation method.

[0007] To achieve the objectives of this invention, the following technical solution is adopted: In a first aspect, the present invention provides a steel wire rope core flame-retardant conveyor belt, comprising a steel wire rope core, an upper adhesive layer, a lower adhesive layer, an upper cover adhesive layer, and a lower cover adhesive layer; wherein the upper cover adhesive layer and the lower cover adhesive layer are independently made from the following raw materials in parts by weight: Styrene-butadiene rubber 55-70 parts, butadiene rubber 20-30 parts, natural rubber 5-15 parts, allylated lamellar boehmite 35-45 parts, submicron zinc borate 8-12 parts, modified flame retardant 4-8 parts, microencapsulated red phosphorus 3-4 parts, antimony trioxide 2-4 parts, reinforcing filler 30-40 parts, silane coupling agent 1.5-2.8 parts, flame retardant lubricant 6-10 parts, chlorinated paraffin 3-6 parts, vulcanization activator 4-7 parts, antioxidant 2-4 parts, accelerator 1.5-2.5 parts, sulfur 1.8-2.5 parts.

[0008] By adopting the above scheme, this invention uses styrene-butadiene rubber, butadiene rubber, and natural rubber as the main body of the cover rubber, taking into account the wear resistance, tear resistance, and elasticity of the conveyor belt. Allylated lamellar boehmite, with its unique high aspect ratio lamellar morphology, replaces traditional aluminum hydroxide and can be arranged along the calendering direction to form a laminated structure under the action of calendering shear field, which significantly extends the crack propagation path. Modified flame retardant, submicron zinc borate, microencapsulated red phosphorus, and antimony trioxide constitute a multi-element synergistic flame retardant system, which improves the defects of single flame retardant agents such as low flame retardant efficiency, easy precipitation, and damage to the mechanical properties of rubber. At the same time, with the help of a special reinforcing system and an additive system, the conveyor belt has both excellent flame retardant and smoke suppression performance and mechanical strength.

[0009] Furthermore, the D50 particle size of the allylated platy boehmite is 0.8~1.2 μm.

[0010] By adopting the above scheme, the lamellar boehmite in this particle size range has good dispersibility in the rubber matrix, which can form an effective physical barrier network, effectively blocking the transfer and diffusion of oxygen, heat and combustible gases, and improving the flame retardant and heat insulation effect. When the particle size is too small, the specific surface area of ​​the lamellar particles is too large, and they are easy to disperse in the rubber matrix due to strong polarity agglomeration. When the particle size is too large, the orientation efficiency and crack deflection effect of the lamellar morphology are reduced, and an effective layered structure cannot be formed.

[0011] Furthermore, the method for preparing the allylated platy boehmite includes the following steps: (1) Ammonia solution is slowly added dropwise to aluminum nitrate solution. The addition is stopped when the pH value is 8.3~8.5. After stirring for 50~60 min, the mixture is centrifuged to obtain the supernatant and the lower gel. The lower gel, water and sodium dodecyl sulfate are mixed to obtain a slurry. The slurry is heated to react and obtain flaky boehmite. (2) Mix flaky boehmite, anhydrous ethanol and water, adjust the pH to 4~4.5, heat and stir, add γ-mercaptopropyltrimethoxysilane and continue stirring for 80~90 min to obtain mercapto-modified boehmite; (3) Mix mercapto-boehmite with anhydrous ethanol evenly, add allyl glycidyl ether and 2,2-dimethoxy-2-phenylacetophenone, bubble with high-purity nitrogen for 15 min, transfer to a UV curing oven, and react at 30~33℃ for 30~40 min to obtain allyl-plated boehmite.

[0012] By adopting the above scheme, boehmite with a plate-like morphology is first prepared, and then modified by mercapto grafting and ultraviolet light allylation, so that active groups that can cross-link with rubber molecules are introduced on the surface of boehmite. The modified boehmite can participate in the vulcanization cross-linking of rubber, transforming from an inorganic filler into a cross-linking active component, which not only improves the flame retardant barrier effect, but also significantly enhances the overall structural strength and wear resistance of the rubber compound.

[0013] Further, in step (1), the concentration of the aluminum nitrate aqueous solution is 1 mol / L; the concentration of the ammonia aqueous solution is 1 mol / L; the mass ratio of the lower gel, water and sodium dodecyl sulfate is 1:(9~10):(0.004~0.008); the reaction temperature is 170~180℃, and the reaction time is 11~12h.

[0014] By adopting the above scheme and using sodium dodecyl sulfate as a morphology regulator, the growth of boehmite along the thickness direction was effectively inhibited and the formation of a plate-like morphology was promoted. The above parameters can ensure that the prepared plate-like boehmite has a regular structure and stable performance.

[0015] Further, in step (2), the mass ratio of the plate-like boehmite, anhydrous ethanol, water and γ-mercaptopropyltrimethoxysilane is 1:(6.2~6.4):(0.3~0.4):(0.024~0.026).

[0016] By employing the above scheme, in an ethanol / water mixed system, the silane coupling agent KH-590 reacts with boehmite to anchor thiol groups onto the particle surface. Under these conditions, the silane coverage density is moderate, providing sufficient reactive sites for subsequent allylation modification.

[0017] Further, in step (2), the heating and stirring are specifically: heating to 65~70℃ and stirring for 15~20 minutes.

[0018] Further, in step (3), the mass ratio of mercapto-boehmite, anhydrous ethanol and allyl glycidyl ether is 1:(7~8):(0.016~0.018); the amount of 2,2-dimethoxy-2-phenylacetophenone used is 3%~3.3% of the mass of allyl glycidyl ether.

[0019] By employing the above-described method, the thiol group reacts with the terminal double bond of allyl glycidyl ether, introducing an allyl functional group onto the particle surface. This reaction is characterized by mild conditions, high conversion rate, few side reactions, and precise control over the degree of functionalization. Simultaneously, some free thiol groups are retained, resulting in a final product possessing both allyl and thiol functional groups.

[0020] Furthermore, the preparation method of the modified flame retardant includes the following steps: A 50% phytic acid aqueous solution was mixed with water at a mass ratio of 1:(2~3). Melamine was added to make the molar ratio of melamine to phytic acid (2.3~2.5):1. The mixture was reacted at 70~75℃ for 50~60 min, filtered, and a precipitate was obtained. The precipitate was mixed with water at a mass ratio of 1:(5~6). A 0.5 mol / L nickel nitrate aqueous solution was slowly added dropwise to make the molar ratio of nickel to phosphorus (0.1~0.2):1. The mixture was reacted at 75~85℃ for 90~100 min. The pH was adjusted to 6.5~7, filtered, washed, and dried to obtain the modified flame retardant.

[0021] By adopting the above scheme, phytic acid with high phosphorus content is first converted into precipitated phytic acid melamine salt, and then nickel nitrate is introduced to form a stable PA-Ni complex. During combustion, the phytic acid portion of this modified flame retardant decomposes before the matrix, releasing phosphoric acid / polyphosphoric acid, which catalyzes the dehydration of the rubber matrix into char. At the same time, nickel ions act as a graphitization catalyst, transforming the disordered char layer into a partially graphitized dense char layer, thereby improving the thermal stability of the char layer. In addition, the modified flame retardant can form a synergistic flame retardant system with inorganic flame retardants such as boehmite and zinc borate, improving the overall flame retardant performance.

[0022] Furthermore, the submicron zinc borate undergoes pretreatment as follows: the submicron zinc borate is selected from zinc borate 3.5 water with a D50 particle size of 0.4~0.6μm, which is wet-grafted with silane coupling agent KH-570 at 0.8%~1.0% of the mass of zinc borate 3.5 water, and then dried.

[0023] By adopting the above scheme, the dispersion uniformity of zinc borate in the rubber matrix is ​​improved, and powder agglomeration is avoided.

[0024] Furthermore, the reinforcing filler is prepared by mixing carbon black N220 and silica VN3 at a mass ratio of (3~5):1.

[0025] By adopting the above scheme, a carbon black and silica compound reinforcement system can be used to combine the advantages of carbon black's high wear resistance and high reinforcing strength with silica's high dispersion, high tear resistance, and aging resistance; forming a double-layer reinforcement structure of carbon black skeleton and silica interface, combined with the laminated structure of lamellar boehmite, to construct a multi-level reinforcement network of the cover adhesive.

[0026] Secondly, the present invention provides a method for preparing the above-mentioned steel wire rope core flame-retardant conveyor belt, comprising the following steps: S1: Plasticize styrene-butadiene rubber, cis-butadiene rubber and natural rubber at 60~70℃ for 3~5min to obtain a rubber matrix; mix allylated flake boehmite, submicron zinc borate, modified flame retardant, microencapsulated red phosphorus and antimony trioxide evenly, add silane coupling agent and stir for 5~8min to obtain a composite filler. S2: Put the rubber matrix into an internal mixer and heat it to 75~85℃ and mix for 2~3 minutes; add composite filler, reinforcing filler, flame retardant lubricant, chlorinated paraffin, vulcanizing activator, and antioxidant, and continue mixing for 5~6 minutes. Discharge the rubber, let it stand at room temperature for 8~20 hours, and then put it back into the internal mixer. Heat it to 65~75℃ and mix for 2 minutes. Add accelerator and sulfur in sequence and mix for 2~3 minutes. Sheet up and cool to obtain flame retardant cover rubber compound. Use the obtained flame retardant cover rubber compound as the lower cover rubber layer and the upper cover rubber layer. S3: The lower cover rubber layer, lower adhesive layer, steel wire rope core, upper adhesive layer and upper cover rubber layer are sequentially bonded together, placed in a flat vulcanizing machine for vulcanization, and cooled to obtain a steel wire rope core flame-retardant conveyor belt.

[0027] By adopting the above scheme, various flame-retardant fillers are first pre-mixed with silane coupling agents, so that the coupling agents are uniformly coated on the surface of the fillers, which improves the dispersibility of the fillers in the rubber compound. A two-stage mixing process is adopted. The first stage of mixing completes the dispersion of the fillers and the composite with the matrix, and the second stage of vulcanization avoids early scorching of the rubber compound, ensuring the safety of the vulcanization process. The final flat vulcanization molding ensures the adhesion strength between the layers of the conveyor belt and the integrity of the overall structure. This preparation method is stable, controllable, and suitable for industrial mass production.

[0028] In summary, the beneficial effects of the present invention are: (1) This invention constructs a synergistic flame retardant system for the covering adhesive by the layered physical barrier effect of allylated plate boehmite, the phosphorus-nickel catalytic char formation effect of the modified flame retardant with phytic acid-nickel coordination complexation, and the gas phase flame retardant mechanism of microencapsulated red phosphorus / antimony trioxide; the three work together to achieve excellent flame retardant effect. (2) The surface of the allylated plate boehmite of the present invention contains three active functional groups: mercapto, allyl and hydroxyl. The allyl group can participate in the vulcanization and crosslinking reaction of the rubber, so that the inorganic filler and the rubber matrix form a covalent bond and improve the interfacial bonding force between the filler and the rubber matrix. At the same time, the free mercapto group can participate in the reaction, further enhancing the integrity of the crosslinking network. Meanwhile, the carbon black and silica compound reinforcement system is used, which combines the performance advantages of the three rubbers, so that the conveyor belt has high tensile strength, tear resistance, wear resistance and deformation resistance. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples and comparative examples are commercially available.

[0031] Preparation Examples 1-4: Preparation of Allylated Platy Boehmite Preparation Example 1 (1) Weigh 187.57g of aluminum nitrate nonahydrate and add it to 500g of deionized water. Stir at 30℃ for 30min to obtain an aluminum nitrate aqueous solution. Slowly add 1.0mol / L ammonia solution to the aluminum nitrate aqueous solution, monitor the pH value throughout the process, and stop adding when the pH value reaches 8.5. Continue stirring for 60min and centrifuge. Discard the supernatant. Repeat centrifugation 3 times, wash, and weigh the lower gel after washing. Add 100g of the lower gel to 980g of deionized water and disperse evenly. Add 0.7g of sodium dodecyl sulfate and stir for 30min to obtain a slurry. Transfer the slurry to a reaction vessel and heat it to 175℃ at a heating rate of 2℃ / min. Keep it at 11h and cool it naturally to room temperature. Centrifuge and wash. Place the washed solid phase in a vacuum drying oven and dry it at 80℃ for 6h to obtain flaky boehmite. (2) Mix 50g of flake boehmite, 320g of anhydrous ethanol and 20g of water, adjust the pH to 4, heat to 70℃ and stir for 18min, add 1.2g of γ-mercaptopropyltrimethoxysilane and continue stirring for 90min. After the reaction is complete, cool, centrifuge and wash to obtain mercapto-modified boehmite. (3) Mix 50g of mercapto-boehmite with 380g of anhydrous ethanol and stir for 15min. Add 0.9g of allyl glycidyl ether and 0.028g of 2,2-dimethoxy-2-phenylacetophenone. Transfer the reaction system to a reactor and bubble it with high-purity nitrogen for 15min. Place the reactor in an ultraviolet curing chamber and turn on the 365nm ultraviolet light source with a power density of 20mW / cm². 2 The reaction was carried out at 33℃ for 30 min. After the reaction was completed, the sample was centrifuged, washed, and dried in a vacuum drying oven at 70℃ for 8 h. The sample was then passed through a 325-mesh sieve to obtain allylated platy boehmite with a D50 particle size of 1.1 μm.

[0032] Preparation Example 2 (1) Weigh 187.57g of aluminum nitrate nonahydrate and add it to 500g of deionized water. Stir at 30℃ for 30min to obtain an aluminum nitrate aqueous solution. Slowly add 1.0mol / L ammonia solution to the aluminum nitrate aqueous solution, monitor the pH value throughout the process, and stop adding when the pH value reaches 8.3. Continue stirring for 55min and centrifuge. Discard the supernatant and repeat centrifugation 3 times. Wash and weigh the lower gel after washing. Add 100g of the lower gel to 920g of deionized water and disperse evenly. Add 0.5g of sodium dodecyl sulfate and stir for 30min to obtain a slurry. Transfer the slurry to a reaction vessel and heat it to 180℃ at a heating rate of 2℃ / min. Keep it at 11.5h and cool it naturally to room temperature. Centrifuge and wash. Place the washed solid phase in a vacuum drying oven and dry it at 80℃ for 6h to obtain flaky boehmite. (2) Mix 50g of flake boehmite, 315g of anhydrous ethanol and 15g of water, adjust the pH to 4.4, heat to 65℃ and stir for 20min, add 1.3g of γ-mercaptopropyltrimethoxysilane and continue stirring for 85min. After the reaction is complete, cool, centrifuge and wash to obtain mercapto-modified boehmite. (3) Mix 50g of mercapto-boehmite with 400g of anhydrous ethanol and stir for 15min. Add 0.85g of allyl glycidyl ether and 0.0275g of 2,2-dimethoxy-2-phenylacetophenone. Transfer the reaction system to a reactor and bubble it with high-purity nitrogen for 15min. Place the reactor in an ultraviolet curing chamber and turn on a 365nm ultraviolet light source with a power density of 20mW / cm². 2 The reaction was carried out at 30℃ for 35 min. After the reaction was completed, the sample was centrifuged, washed, and dried in a vacuum drying oven at 70℃ for 8 h. The sample was then passed through a 325-mesh sieve to obtain allylated plate boehmite with a D50 particle size of 1.2 μm.

[0033] Preparation Example 3 (1) Weigh 187.57g of aluminum nitrate nonahydrate and add it to 500g of deionized water. Stir at 30℃ for 30min to obtain an aluminum nitrate aqueous solution. Slowly add 1.0mol / L ammonia solution to the aluminum nitrate aqueous solution, monitor the pH value throughout the process, and stop adding when the pH value reaches 8.3. Continue stirring for 50min and centrifuge. Discard the supernatant and repeat centrifugation 3 times. Wash and weigh the lower gel after washing. Add 100g of the lower gel to 1000g of deionized water and disperse evenly. Add 0.6g of sodium dodecyl sulfate and stir for 30min to obtain a slurry. Transfer the slurry to a reaction vessel and heat it to 170℃ at a heating rate of 2℃ / min. Keep it at 12h and cool it naturally to room temperature. Centrifuge and wash. Place the washed solid phase in a vacuum drying oven and dry it at 80℃ for 6h to obtain flaky boehmite. (2) Mix 50g of flake boehmite, 310g of anhydrous ethanol and 20g of water, adjust the pH to 4, heat to 66℃ and stir for 20min, add 1.28g of γ-mercaptopropyltrimethoxysilane and continue stirring for 80min. After the reaction is complete, cool, centrifuge and wash to obtain mercapto-modified boehmite. (3) Mix 50g of mercapto-boehmite with 350g of anhydrous ethanol and stir for 15min. Add 0.82g of allyl glycidyl ether and 0.025g of 2,2-dimethoxy-2-phenylacetophenone. Transfer the reaction system to a reactor and bubble it with high-purity nitrogen for 15min. Place the reactor in an ultraviolet curing chamber and turn on the 365nm ultraviolet light source with a power density of 20mW / cm². 2 The reaction was carried out at 33℃ for 40 min. After the reaction was completed, the sample was centrifuged, washed, and dried in a vacuum drying oven at 70℃ for 8 h. The sample was then passed through a 325-mesh sieve to obtain allylated plate boehmite with a D50 particle size of 0.9 μm.

[0034] Preparation Example 4 (1) Weigh 187.57g of aluminum nitrate nonahydrate and add it to 500g of deionized water. Stir at 30℃ for 30min to obtain an aluminum nitrate aqueous solution. Slowly add 1.0mol / L ammonia solution to the aluminum nitrate aqueous solution, monitor the pH value throughout the process, and stop adding when the pH value reaches 8.5. Continue stirring for 55min and centrifuge. Discard the supernatant and repeat centrifugation 3 times. Wash and weigh the lower gel after washing. Add 100g of the lower gel to 950g of deionized water and disperse evenly. Add 0.8g of sodium dodecyl sulfate and stir for 30min to obtain a slurry. Transfer the slurry to a reaction vessel and heat it to 175℃ at a heating rate of 2℃ / min. Keep it at 11.5h and cool it naturally to room temperature. Centrifuge and wash. Place the washed solid phase in a vacuum drying oven and dry it at 80℃ for 6h to obtain flaky boehmite. (2) Mix 50g of flake boehmite, 315g of anhydrous ethanol and 15g of water, adjust the pH to 4.2, heat to 70℃ and stir for 20min, add 1.28g of γ-mercaptopropyltrimethoxysilane and continue stirring for 82min. After the reaction is complete, cool, centrifuge and wash to obtain mercapto-modified boehmite. (3) Mix 50g of mercapto-boehmite with 360g of anhydrous ethanol and stir for 15min. Add 0.9g of allyl glycidyl ether and 0.0288g of 2,2-dimethoxy-2-phenylacetophenone. Transfer the reaction system to a reactor and bubble it with high-purity nitrogen for 15min. Place the reactor in an ultraviolet curing chamber and turn on the 365nm ultraviolet light source with a power density of 20mW / cm². 2The reaction was carried out at 31℃ for 35 min. After the reaction was completed, the sample was centrifuged, washed, and dried in a vacuum drying oven at 70℃ for 8 h. The sample was then passed through a 325-mesh sieve to obtain allylated platy boehmite with a D50 particle size of 1 μm.

[0035] Preparation Examples 5-7: Preparation of Modified Flame Retardants Preparation Example 5 A 50% phytic acid aqueous solution was mixed with water at a mass ratio of 1:3 and stirred for 30 min. Melamine was then added to achieve a molar ratio of melamine to phytic acid of 2.45:1. The mixture was reacted at 75°C for 50 min, filtered, and dried to obtain a precipitate. The precipitate was then mixed with water at a mass ratio of 1:5 and stirred for 20 min. A 0.5 mol / L nickel nitrate aqueous solution was slowly added dropwise to achieve a molar ratio of nickel to phosphorus of 0.2:1. The mixture was reacted at 75°C for 95 min. The pH was adjusted to 7, filtered, washed, and dried in a vacuum drying oven at 90°C for 8 h. The product was then passed through a 400-mesh sieve to obtain the modified flame retardant.

[0036] Preparation Example 6 A 50% phytic acid aqueous solution was mixed with water at a mass ratio of 1:2 and stirred for 30 min. Melamine was then added to achieve a molar ratio of melamine to phytic acid of 2.35:1. The mixture was reacted at 70℃ for 55 min, filtered, and dried to obtain a precipitate. The precipitate was then mixed with water at a mass ratio of 1:6 and stirred for 20 min. A 0.5 mol / L nickel nitrate aqueous solution was slowly added dropwise to achieve a molar ratio of nickel to phosphorus of 0.16:1. The mixture was reacted at 85℃ for 92 min, and the pH was adjusted to 6.8. The mixture was then filtered, washed, and dried in a vacuum drying oven at 90℃ for 8 h. The dried product was then passed through a 400-mesh sieve to obtain the modified flame retardant.

[0037] Preparation Example 7 A 50% phytic acid aqueous solution was mixed with water at a mass ratio of 1:3 and stirred for 30 min. Melamine was then added to achieve a molar ratio of melamine to phytic acid of 2.5:1. The mixture was reacted at 70℃ for 60 min, filtered, and dried to obtain a precipitate. The precipitate was then mixed with water at a mass ratio of 1:5 and stirred for 20 min. A 0.5 mol / L nickel nitrate aqueous solution was slowly added dropwise to achieve a molar ratio of nickel to phosphorus of 0.1:1. The mixture was reacted at 80℃ for 100 min, and the pH was adjusted to 6.6. The mixture was then filtered, washed, and dried in a vacuum drying oven at 90℃ for 8 h. The dried product was then passed through a 400-mesh sieve to obtain the modified flame retardant.

[0038] Examples 1-4: Preparation of flame-retardant steel wire rope core conveyor belts Example 1 This embodiment of a steel wire rope core flame-retardant conveyor belt includes a steel wire rope core, an upper adhesive layer, a lower adhesive layer, an upper cover adhesive layer, and a lower cover adhesive layer; the upper cover adhesive layer and the lower cover adhesive layer are independently made from the following raw materials in parts by weight: 63 parts of styrene-butadiene rubber, 24 parts of cis-butadiene rubber, 12 parts of natural rubber, 40 parts of allylated lamellar boehmite obtained in Preparation Example 2, 10 parts of submicron zinc borate, 5 parts of modified flame retardant obtained in Preparation Example 5, 3 parts of microencapsulated red phosphorus, 3 parts of antimony trioxide, 30 parts of reinforcing filler, 2.6 parts of silane coupling agent, 9 parts of flame retardant lubricant, 5 parts of chlorinated paraffin, 5.5 parts of vulcanizing activator, 2.8 parts of antioxidant, 1.6 parts of accelerator, and 2 parts of sulfur; The submicron zinc borate was pretreated as follows: Zinc borate 3.5 water with a D50 particle size of 0.5 μm was selected and wet-grafted using silane coupling agent KH-570 at 1.0% of the mass of zinc borate 3.5 water, followed by drying. The reinforcing filler is prepared by mixing carbon black N220 and silica VN3 in a ratio of 3.5:1; The silane coupling agent is bis-[3-(triethoxysilyl)propyl]tetrasulfide Si-69; The flame-retardant lubricant is MB-202; The vulcanizing activator is prepared by mixing zinc oxide and stearic acid in a mass ratio of 2:1; The antioxidant is prepared by mixing antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1. The accelerator is prepared by mixing accelerator CZ and accelerator DM at a mass ratio of 1.25:1.

[0039] The specific steps of the preparation method of the steel wire rope core flame-retardant conveyor belt in this embodiment are as follows: S1: Plasticize styrene-butadiene rubber, cis-butadiene rubber and natural rubber at 60℃ for 5 min to obtain a rubber matrix; mix allylated flake boehmite, submicron zinc borate, modified flame retardant, microencapsulated red phosphorus and antimony trioxide evenly, add silane coupling agent and stir for 7 min to obtain composite filler. S2: Put the rubber matrix into a mixer and heat it to 80°C to mix for 2 minutes; add composite filler, reinforcing filler, flame retardant lubricant, chlorinated paraffin, vulcanizing activator, and antioxidant, and continue mixing for 5 minutes, with the temperature not exceeding 110°C; discharge the rubber, with the discharge temperature not exceeding 150°C, and let it stand at room temperature for 18 hours before putting it back into the mixer, heating it to 70°C and mixing for 2 minutes; add the accelerator and sulfur in sequence and mix for 2 minutes; sheet and cool to obtain the flame retardant cover rubber compound; use the obtained flame retardant cover rubber compound as the lower cover rubber layer and the upper cover rubber layer. S3: The special bonding intermediate rubber for steel cord conveyor belts is pressed by a calender to obtain a bonding rubber sheet, which serves as the lower bonding rubber layer and the upper bonding rubber layer; the lower cover rubber layer, the lower bonding rubber layer, the steel cord, the upper bonding rubber layer and the upper cover rubber layer are sequentially bonded together, placed in a flat vulcanizing machine for vulcanization, and cooled to obtain a steel cord flame-retardant conveyor belt.

[0040] Example 2 This embodiment of a steel wire rope core flame-retardant conveyor belt includes a steel wire rope core, an upper adhesive layer, a lower adhesive layer, an upper cover adhesive layer, and a lower cover adhesive layer; the upper cover adhesive layer and the lower cover adhesive layer are independently made from the following raw materials in parts by weight: 60 parts of styrene-butadiene rubber, 25 parts of butadiene rubber, 8 parts of natural rubber, 42 parts of allylated lamellar boehmite prepared in Preparation Example 1, 9 parts of submicron zinc borate, 5 parts of modified flame retardant prepared in Preparation Example 5, 3.3 parts of microencapsulated red phosphorus, 2.5 parts of antimony trioxide, 36 parts of reinforcing filler, 1.8 parts of silane coupling agent, 7 parts of flame retardant lubricant, 4.5 parts of chlorinated paraffin, 6 parts of vulcanizing activator, 3 parts of antioxidant, 2.2 parts of accelerator, and 2.4 parts of sulfur; The submicron zinc borate was pretreated as follows: 3.5-hydrate zinc borate with a D50 particle size of 0.6 μm was selected and wet-grafted with silane coupling agent KH-570 at 0.8% of the mass of 3.5-hydrate zinc borate, and then dried. The reinforcing filler is prepared by mixing carbon black N220 and silica VN3 in a ratio of 5:1; The silane coupling agent is bis-[3-(triethoxysilyl)propyl]tetrasulfide Si-69; The flame-retardant lubricant is MB-202; The vulcanizing activator is prepared by mixing zinc oxide and stearic acid in a mass ratio of 2:1; The antioxidant is prepared by mixing antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1. The accelerator is prepared by mixing accelerator CZ and accelerator DM at a mass ratio of 1.25:1.

[0041] The specific steps of the preparation method of the steel wire rope core flame-retardant conveyor belt in this embodiment are as follows: S1: Plasticize styrene-butadiene rubber, cis-butadiene rubber and natural rubber at 65°C for 4 min to obtain a rubber matrix; mix allylated flake boehmite, submicron zinc borate, modified flame retardant, microencapsulated red phosphorus and antimony trioxide evenly, add silane coupling agent and stir for 6 min to obtain a composite filler. S2: Put the rubber matrix into an internal mixer and heat it to 80°C to mix for 3 minutes; add composite filler, reinforcing filler, flame retardant lubricant, chlorinated paraffin, vulcanizing activator, and antioxidant, and continue mixing for 6 minutes, with the temperature not exceeding 110°C; discharge the rubber, with the discharge temperature not exceeding 150°C, and let it stand at room temperature for 14 hours before putting it back into the internal mixer, heating it to 75°C and mixing for 2 minutes; add the accelerator and sulfur in sequence and mix for 3 minutes; sheet and cool to obtain the flame retardant cover rubber compound; use the obtained flame retardant cover rubber compound as the lower cover rubber layer and the upper cover rubber layer. S3: The special bonding intermediate rubber for steel cord conveyor belts is pressed by a calender to obtain a bonding rubber sheet, which serves as the lower bonding rubber layer and the upper bonding rubber layer; the lower cover rubber layer, the lower bonding rubber layer, the steel cord, the upper bonding rubber layer and the upper cover rubber layer are sequentially bonded together, placed in a flat vulcanizing machine for vulcanization, and cooled to obtain a steel cord flame-retardant conveyor belt.

[0042] Example 3 This embodiment of a steel wire rope core flame-retardant conveyor belt includes a steel wire rope core, an upper adhesive layer, a lower adhesive layer, an upper cover adhesive layer, and a lower cover adhesive layer; the upper cover adhesive layer and the lower cover adhesive layer are independently made from the following raw materials in parts by weight: 62 parts of styrene-butadiene rubber, 27 parts of butadiene rubber, 10 parts of natural rubber, 38 parts of allylated lamellar boehmite prepared in Preparation Example 1, 11 parts of submicron zinc borate, 6 parts of modified flame retardant prepared in Preparation Example 6, 3 parts of microencapsulated red phosphorus, 2 parts of antimony trioxide, 36 parts of reinforcing filler, 2.2 parts of silane coupling agent, 8 parts of flame retardant lubricant, 3.5 parts of chlorinated paraffin, 5 parts of vulcanizing activator, 4 parts of antioxidant, 2 parts of accelerator, and 2 parts of sulfur; The submicron zinc borate was pretreated as follows: 3.5-hydrate zinc borate with a D50 particle size of 0.6 μm was selected and wet-grafted with silane coupling agent KH-570 at 1.0% of the mass of 3.5-hydrate zinc borate, and then dried. The reinforcing filler was prepared by mixing carbon black N220 and silica VN3 in a ratio of 4:1; The silane coupling agent is bis-[3-(triethoxysilyl)propyl]tetrasulfide Si-69; The flame-retardant lubricant is MB-202; The vulcanizing activator is prepared by mixing zinc oxide and stearic acid in a mass ratio of 2:1; The antioxidant is prepared by mixing antioxidant 4010NA and antioxidant RD in a mass ratio of 1:1. The accelerator is prepared by mixing accelerator CZ and accelerator DM at a mass ratio of 1.25:1.

[0043] The specific steps of the preparation method of the steel wire rope core flame-retardant conveyor belt in this embodiment are as follows: S1: Plasticize styrene-butadiene rubber, cis-butadiene rubber and natural rubber at 60℃ for 5 min to obtain a rubber matrix; mix allylated flake boehmite, submicron zinc borate, modified flame retardant, microencapsulated red phosphorus and antimony trioxide evenly, add silane coupling agent and stir for 8 min to obtain composite filler. S2: Put the rubber matrix into an internal mixer and heat it to 75°C and mix for 2 minutes; add composite filler, reinforcing filler, flame retardant lubricant, chlorinated paraffin, vulcanizing activator, and antioxidant, and continue mixing for 5 minutes, with the temperature not exceeding 110°C; discharge the rubber, with the discharge temperature not exceeding 150°C, and let it stand at room temperature for 12 hours before putting it back into the internal mixer, heating it to 75°C and mixing for 2 minutes; add the accelerator and sulfur in sequence and mix for 2 minutes; sheet and cool to obtain the flame retardant cover rubber compound; use the obtained flame retardant cover rubber compound as the lower cover rubber layer and the upper cover rubber layer. S3: The special bonding intermediate rubber for steel cord conveyor belts is pressed by a calender to obtain a bonding rubber sheet, which serves as the lower bonding rubber layer and the upper bonding rubber layer; the lower cover rubber layer, the lower bonding rubber layer, the steel cord, the upper bonding rubber layer and the upper cover rubber layer are sequentially bonded together, placed in a flat vulcanizing machine for vulcanization, and cooled to obtain a steel cord flame-retardant conveyor belt.

[0044] Example 4 The difference from Example 1 is that: The top and bottom cover adhesive layers are independently prepared from the following raw materials in parts by weight: 68 parts of styrene-butadiene rubber, 22 parts of butadiene rubber, 10 parts of natural rubber, 38 parts of allylated lamellar boehmite prepared in Preparation Example 1, 9 parts of submicron zinc borate, 5 parts of modified flame retardant prepared in Preparation Example 6, 3.5 parts of microencapsulated red phosphorus, 2.5 parts of antimony trioxide, 38 parts of reinforcing filler, 2 parts of silane coupling agent, 7 parts of flame retardant lubricant, 4 parts of chlorinated paraffin, 6 parts of vulcanization activator, 3 parts of antioxidant, 2 parts of accelerator, and 2 parts of sulfur; The rest are the same as in Example 1.

[0045] Comparative Examples 1-3: Preparation of Flame-Retardant Conveyor Belts with Steel Wire Rope Cores Comparative Example 1 The difference from Example 1 is that this comparative example does not contain allylated plate boehmite, but is otherwise the same as Example 1.

[0046] Comparative Example 2 The difference from Example 1 is that: in this comparative example, aluminum hydroxide is used instead of allylated plate boehmite in equal parts by weight, and all other aspects are the same as in Example 1.

[0047] Comparative Example 3 The difference from Example 1 is that no modified flame retardant was added in this comparative example, but everything else is the same as in Example 1.

[0048] Related performance tests The steel wire rope core flame-retardant conveyor belts prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to relevant performance tests, and the test results are shown in Table 1.

[0049] Table 1 Test Results

[0050] The steel wire rope core flame-retardant conveyor belts prepared in Examples 1-4 of this invention meet all the requirements, have excellent flame-retardant performance, and the burning time with and without flame is far below the limit value; the cover rubber has good tensile strength, elongation and wear resistance, and the performance decay after thermal aging is small, with excellent aging resistance and fatigue resistance; the roller friction temperature is low, there are no sparks throughout the process, and the use safety is high.

[0051] Comparative Examples 1, 2, and 3 showed decreased flame retardant effect, prolonged burning time, and the appearance of small sparks and excessive temperature due to roller friction. Table 1 shows that neither allylated plate boehmite nor modified flame retardant can meet the flame retardant standard requirements when used alone. The synergistic effect of the two achieves simultaneous improvement in flame retardant performance and mechanical properties.

[0052] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A flame-retardant conveyor belt with a steel wire rope core, characterized in that, It includes a steel wire rope core, an upper adhesive layer, a lower adhesive layer, an upper cover adhesive layer, and a lower cover adhesive layer; the upper cover adhesive layer and the lower cover adhesive layer are independently prepared by weight parts from the following raw materials: 55-70 parts of styrene-butadiene rubber, 20-30 parts of cis-butadiene rubber, 5-15 parts of natural rubber, 35-45 parts of allylated lamellar boehmite, 8-12 parts of submicron zinc borate, 4-8 parts of modified flame retardant, 3-4 parts of microencapsulated red phosphorus, 2-4 parts of antimony trioxide, 30-40 parts of reinforcing filler, 1.5-2.8 parts of silane coupling agent, 6-10 parts of flame retardant lubricant, 3-6 parts of chlorinated paraffin, 4-7 parts of vulcanizing activator, 2-4 parts of antioxidant, 1.5-2.5 parts of accelerator, and 1.8-2.5 parts of sulfur; the preparation method of allylated lamellar boehmite includes the following steps: (1) ammonia water The solution was slowly added dropwise to the aluminum nitrate aqueous solution. The addition was stopped when the pH value was 8.3~8.

5. After stirring for 50~60 min, the solution was centrifuged to obtain the supernatant and the lower gel. The lower gel, water and sodium dodecyl sulfate were mixed to obtain a slurry. The slurry was heated to react to obtain flake boehmite. (2) The flake boehmite, anhydrous ethanol and water were mixed, the pH value was adjusted to 4~4.5, the temperature was raised and stirred, γ-mercaptopropyltrimethoxysilane was added and stirring was continued for 80~90 min to obtain mercapto boehmite. (3) Mercapto boehmite and anhydrous ethanol were mixed evenly, allyl glycidyl ether and 2,2-dimethoxy-2-phenylacetophenone were added, high-purity nitrogen gas was bubbled for 15 min, and then transferred to an ultraviolet curing box and reacted at 30~33℃ for 30~40 min to obtain allyl boehmite.

2. The steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, The D50 particle size of the allylated platy boehmite is 0.8~1.2 μm.

3. The steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, In step (1), the concentration of the aluminum nitrate aqueous solution is 1 mol / L; the concentration of the ammonia aqueous solution is 1 mol / L; the mass ratio of the lower gel, water and sodium dodecyl sulfate is 1:(9~10):(0.004~0.008); the reaction temperature is 170~180℃ and the reaction time is 11~12h.

4. The steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, In step (2), the mass ratio of the plate-like boehmite, anhydrous ethanol, water and γ-mercaptopropyltrimethoxysilane is 1:(6.2~6.4):(0.3~0.4):(0.024~0.026).

5. A steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, In step (3), the mass ratio of mercapto-boehmite, anhydrous ethanol and allyl glycidyl ether is 1:(7~8):(0.016~0.018); the amount of 2,2-dimethoxy-2-phenylacetophenone used is 3%~3.3% of the mass of allyl glycidyl ether.

6. The steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, The preparation method of the modified flame retardant includes the following steps: 50% phytic acid aqueous solution and water are mixed evenly at a mass ratio of 1:(2~3), melamine is added, and the molar ratio of melamine to phytic acid is (2.3~2.5):

1. The mixture is reacted at 70~75℃ for 50~60 min, filtered, and a precipitate is obtained. The precipitate is mixed evenly with water at a mass ratio of 1:(5~6), and a 0.5mol / L nickel nitrate aqueous solution is slowly added dropwise, and the molar ratio of nickel to phosphorus is (0.1~0.2):

1. The mixture is reacted at 75~85℃ for 90~100 min, the pH value is adjusted to 6.5~7, filtered, washed, and dried to obtain the modified flame retardant.

7. A steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, The submicron zinc borate is pretreated as follows: the submicron zinc borate is selected from zinc borate 3,5-hydrate with a D50 particle size of 0.4~0.6μm, which is wet-grafted with silane coupling agent KH-570 at 0.8%~1.0% of the mass of zinc borate 3,5-hydrate, and then dried.

8. A steel wire rope core flame-retardant conveyor belt according to claim 1, characterized in that, The reinforcing filler is prepared by mixing carbon black N220 and silica VN3 in a mass ratio of (3~5):

1.

9. A method for preparing a steel wire rope core flame-retardant conveyor belt according to any one of claims 1-8, characterized in that, The process includes the following steps: S1: Plasticizing styrene-butadiene rubber, butadiene rubber, and natural rubber at 60-70℃ for 3-5 minutes to obtain a rubber matrix; mixing allylated flake boehmite, submicron zinc borate, modified flame retardant, microencapsulated red phosphorus, and antimony trioxide evenly, adding a silane coupling agent and stirring for 5-8 minutes to obtain a composite filler; S2: Putting the rubber matrix into an internal mixer and heating to 75-85℃ for 2-3 minutes; adding the composite filler, reinforcing filler, flame retardant lubricant, chlorinated paraffin, and vulcanizing activator. Add antioxidant, continue mixing for 5-6 minutes, discharge the rubber, let stand at room temperature for 8-20 hours, then put it back into the internal mixer, heat to 65-75℃ and mix for 2 minutes, add accelerator and sulfur in sequence and mix for 2-3 minutes, then sheet and cool to obtain flame retardant cover rubber compound, use the obtained flame retardant cover rubber compound as the lower cover rubber layer and upper cover rubber layer; S3: sequentially bond the lower cover rubber layer, lower adhesive layer, steel wire rope core, upper adhesive layer and upper cover rubber layer, place in a flat vulcanizing machine for vulcanization, cool to obtain steel wire rope core flame retardant conveyor belt.

Images