Rubber surface aramid fiber fabric whole core flame-retardant conveying belt and manufacturing method thereof

Abstract

The invention relates to a rubber surface aramid fiber fabric whole core flame-retardant conveying belt and a manufacturing method thereof, and belongs to the technical field of conveying belts, a flame-retardant bonding rubber layer is added between a belt core and a covering rubber layer, a nitrile rubber and natural rubber blending system is adopted, and a resorcinol resin and white carbon black composite bonding accelerant is matched, so that the flame-retardant conveying belt is obtained. Interface bonding is enhanced through double effects of chemical bonding and physical adsorption, and meanwhile, the process sequence is optimized, namely, the flame-retardant bonding rubber layer is thermally bonded with the plasticized belt core through four-roller calendering, and then is compounded with the covering rubber layer, so that the flame-retardant bonding rubber layer is tightly bonded with the plasticized belt core and the covering rubber layer without bubbles; finally, the bonding strength of the covering rubber layer and the plasticized belt core is improved to 14.8-17.3 N / mm and far exceeds the MT / T914 standard requirement, the layering and degumming problem is thoroughly solved, the tensile strength, the elongation at break and the wear resistance of the covering rubber layer are all superior to the standard, and the long service life and the structural integrity of the conveying belt under the working conditions of high-strength wear and frequent impact are guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of conveyor belt technology and relates to a rubber-faced aramid fabric solid core flame-retardant conveyor belt and its manufacturing method. Background Technology

[0002] Conveyor belts are widely used in coal mines, ports, chemical industries, and other fields. High-risk environments such as coal mines place extremely high demands on the flame retardancy, antistatic properties, mechanical strength, interlayer adhesion, and wear resistance of conveyor belts. Currently, the high-strength conveyor belts commonly used in coal mines are mostly steel cord conveyor belts conforming to the MT / T668 standard. However, steel cord conveyor belts suffer from problems such as heavy weight, inconvenient installation and maintenance, susceptibility to corrosion, and high cost. Existing aramid fabric conveyor belts are mostly a binary structure of "belt core-cover rubber layer," with the belt core being a single layer of straight warp and weft aramid impregnated canvas. Even with impregnation treatment, there are still issues such as insufficient adhesion strength between the cover rubber layer and the belt core, easy delamination and peeling after long-term use, and the belt core is not flame retardant, failing to meet the flame retardant performance requirements of the MT / T914 "Flame-retardant Fabric Core Conveyor Belts for Coal Mines" standard. Furthermore, the ratio of transverse to longitudinal strength is unreasonable, resulting in poor longitudinal tear resistance, difficult splicing, and low splice strength, making them an ineffective replacement for steel cord flame-retardant conveyor belts.

[0003] Chinese invention patent application CN120621965A discloses a thermoplastic solid woven flame-retardant conveyor belt and its manufacturing method, which consists of a core layer, a flame-retardant covering rubber layer, a wear-resistant layer, and a flame-retardant adhesive rubber layer. The core layer is made of three layers of aramid / polyester blended woven fabric (radial linear density ≥5000N / cm) impregnated with halogen-free flame-retardant polyurethane rubber (containing APP 5phr and zinc borate 10phr); the flame-retardant covering rubber layer is an EVA-based composite, with an intumescent flame-retardant system composed of microencapsulated red phosphorus 5phr, magnesium hydroxide 20phr, and melamine cyanurate 8phr; the surface wear-resistant layer is ultra-high molecular weight polyethylene (Mw≥3×106, thickness 0.8-1.5mm), which has the advantages of high strength and lightweight, flame retardancy, and high joint strength retention rate, and is suitable for heavy-duty and high-temperature scenarios such as mining and metallurgy.

[0004] The conveyor belt in the above technical solution has the problem of poor interfacial bonding stability of thermoplastic materials. In particular, the polyurethane adhesive bonding system is prone to hydrolysis and peeling in humid and hot environments. In addition, the wear-resistant layer is co-extruded with ultra-high molecular weight polyethylene, which only forms a mechanical interlock with the EVA-based covering adhesive layer through molecular chain penetration. The interfacial bonding force is weak, and it is easy to detach under long-term dynamic friction. It cannot meet the long-term use requirements of high strength and high wear in coal mine scenarios. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant conveyor belt with rubber-faced aramid fabric and its manufacturing method. By adding a flame-retardant adhesive rubber layer between the belt core and the cover rubber layer, and optimizing the process and formula, the invention achieves the effects of improving interlayer bonding strength, high strength and lightweight.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A rubber-faced aramid fabric solid core flame-retardant conveyor belt comprises, from the inside out, an aramid fabric integral belt core, an impregnated rubber layer, a flame-retardant adhesive rubber layer, and a cover rubber layer. The aramid fabric integral belt core is a 4-5 layer woven structure of aramid, nylon, and cotton fibers, wherein the warp is 70-80wt% aramid and 20-30wt% cotton blended fiber, and the weft is 60-70wt% nylon and 30-40wt% cotton blended fiber.

[0008] Furthermore, the impregnated adhesive layer is formed by impregnating and plasticizing an impregnating adhesive material, wherein the viscosity of the impregnating adhesive material is 4800-5100 mPa•s.

[0009] Furthermore, the adhesive strength of the covering layer is ≥14 N / mm, and the abrasion loss is ≤120 mm. 3 .

[0010] Furthermore, the overall internal bonding strength of the aramid fabric core is ≥15N / mm.

[0011] Furthermore, the warp density is 180-200 warp threads / 10cm, with a strength of 2500 N / mm; the warp density is 280-300 warp threads / 10cm, with a strength of 4000 N / mm; the warp density is 380-400 warp threads / 10cm, with a strength of 5400 N / mm; the warp density is 520-540 warp threads / 10cm, with a strength of 7500 N / mm; and the weft density is 60-70% of the corresponding warp density.

[0012] Furthermore, the impregnating compound, by weight, comprises the following components:

[0013] 100 parts PVC paste resin, 40-60 parts plasticizer, 30-50 parts flame retardant, 2-5 parts stabilizer, 3-8 parts antistatic agent, and 10-20 parts filler.

[0014] Furthermore, the plasticizer is a phthalate plasticizer.

[0015] Furthermore, the flame retardant is composed of antimony trioxide and aluminum hydroxide mixed in a mass ratio of 1:2.

[0016] Furthermore, the stabilizer is a metal soap stabilizer.

[0017] Furthermore, the antistatic agent is a quaternary ammonium salt type antistatic agent.

[0018] Furthermore, the filler is an inorganic filler.

[0019] Furthermore, the flame-retardant adhesive rubber layer, by weight, comprises the following components:

[0020] The ingredients are: 60-70 parts nitrile rubber, 30-40 parts natural rubber, 15-25 parts flame retardant, 5-10 parts adhesion accelerator, 20-30 parts carbon black, 1-2 parts vulcanizing agent and 0.8-1.5 parts accelerator.

[0021] Furthermore, the flame retardant is an aromatic bromide among bromine-based flame retardants.

[0022] Furthermore, the adhesion promoter is composed of resorcinol resin and fumed silica mixed in a mass ratio of 1:3.

[0023] Furthermore, the accelerator is a thiuram-based accelerator.

[0024] Furthermore, the adhesive layer, by weight, comprises the following components:

[0025] 50-60 parts natural rubber, 40-50 parts styrene-butadiene rubber, 30-40 parts carbon black, 20-30 parts flame retardant, 5-10 parts antistatic agent, 1.5-2.5 parts vulcanizing agent, 1-2 parts accelerator and 5-10 parts softener.

[0026] Furthermore, the flame retardant is an aromatic bromide among bromine-based flame retardants.

[0027] Furthermore, the antistatic agent is made by mixing conductive carbon black and antistatic masterbatch at a mass ratio of 3:1.

[0028] Furthermore, the accelerator is a sulfenamide accelerator.

[0029] Furthermore, the softener is a mineral oil-based softener.

[0030] A method for manufacturing a rubber-faced aramid fabric solid core flame-retardant conveyor belt includes the following steps:

[0031] Step 1: Use a high-speed warp knitting machine to weave the warp and weft threads into a 4-5 layer integral core. Control the tension at 5-8N during the weaving process and use interlayer interlacing to fix it, thus obtaining an integral aramid fabric core.

[0032] Step 2: Place the aramid fabric core and the impregnating material in the impregnation tank, vacuum impregnate and plasticize to obtain a plasticized core with an impregnating layer.

[0033] Step 3: After plasticizing nitrile rubber and natural rubber, add carbon black, flame retardant and adhesion accelerator and mix. Finally, add vulcanizing agent and accelerator and finish mixing. Let stand for 6-8 hours to obtain flame retardant adhesive rubber layer compound.

[0034] Step 4: After plasticizing natural rubber and styrene-butadiene rubber, add carbon black, flame retardant, antistatic agent and softener and mix. Finally, add vulcanizing agent and accelerator and finish mixing. Let stand for 8-12 hours to obtain the cover rubber layer compound.

[0035] Step 5: Use a four-roll calender to perform two-step adhesive application. First, apply flame-retardant adhesive rubber to both the upper and lower surfaces of the plasticized belt core, and calender to form a flame-retardant adhesive rubber layer. Then, apply a cover adhesive layer to the outer surface of the flame-retardant adhesive rubber layer, and calender to form a cover adhesive layer, thus obtaining the conveyor belt blank.

[0036] Step 6: Vulcanize the conveyor belt blank at a temperature of 145-155℃ and a pressure of 2.5-3.0MPa for 30-40 minutes, then cool it to obtain a rubber-faced aramid fabric solid core flame-retardant conveyor belt.

[0037] Furthermore, the vacuum degree of vacuum impregnation is -0.07 to -0.09 MPa, and the vacuum impregnation time is 4-5 min.

[0038] Furthermore, the plasticizing temperature is 170-180℃, and the time is 20-30 minutes.

[0039] Furthermore, when applying the flame-retardant adhesive rubber layer, the temperature of the upper roller is 70-80℃, and the temperature of the middle roller is 65-75℃.

[0040] Furthermore, when applying the adhesive layer, the temperature of the upper roller is 80-90℃ and the temperature of the lower roller is 70-80℃.

[0041] Furthermore, the rolling speed is 5-15 m / min.

[0042] Furthermore, the roller speed ratio of the four-roll calender is 1:1.3:1.3:1.

[0043] Furthermore, the thickness of the flame-retardant adhesive rubber layer is 1-2 mm.

[0044] Furthermore, the thickness of the adhesive layer is 4-8 mm.

[0045] The beneficial effects of this invention are:

[0046] 1. This invention adds a flame-retardant adhesive rubber layer between the belt core and the cover rubber layer. It adopts a blend system of nitrile rubber and natural rubber, combined with a composite adhesive accelerator of resorcinol resin and fumed silica. The interfacial bonding is strengthened through the dual effects of chemical bonding and physical adsorption. At the same time, the process sequence is optimized. First, the flame-retardant adhesive rubber layer is thermally bonded to the plasticized belt core through four-roll calendering, and then it is compounded with the cover rubber layer. This ensures that the flame-retardant adhesive rubber layer is tightly bonded to the plasticized belt core and the cover rubber layer without air bubbles. Finally, the bonding strength between the cover rubber layer and the plasticized belt core is increased to 14.8-17.3 N / mm, which far exceeds the requirements of the MT / T914 standard. This completely solves the problem of delamination and debonding. Moreover, the tensile strength, elongation at break and wear resistance of the cover rubber layer are all superior to the standard, ensuring the long service life and structural integrity of the conveyor belt under high-intensity wear and frequent impact conditions.

[0047] 2. This invention adopts a 4-5 layer aramid, nylon, and cotton mixed woven integral belt core structure. Through precise control of the warp and weft density ratio, 5-8N weaving tension, and interlayer interlacing fixing process, it achieves a series of high longitudinal strengths ranging from 2500N / mm to 7500N / mm, with the transverse strength consistently reaching more than 50% of the longitudinal strength. It completely covers and replaces the strength level of the same grade of steel cord conveyor belt (MT / T668). The unique weft nylon and cotton design ensures that the transverse strength consistently reaches more than 50% of the longitudinal strength, effectively overcoming the problems of insufficient transverse strength, poor longitudinal tear resistance, difficulty in jointing, and insufficient joint strength of existing aramid fabric conveyor belts. In addition, the density of aramid fiber is only 1 / 5 of that of steel wire, making the rubber-faced aramid fabric integral flame-retardant conveyor belt about 30% lighter than the same grade of steel cord belt, significantly reducing equipment operating energy consumption, reducing wear on idlers and transmission systems, and achieving a perfect balance between high strength and lightweight.

[0048] 3. This invention, from the core impregnation compound (PVC / flame retardant plasticizer / composite flame retardant) to the cover layer and flame retardant adhesive rubber layer (synergistic use of halogenated / inorganic flame retardants), precisely matches the selection and ratio of flame retardants in each layer to functional requirements. The impregnation compound uses PVC paste resin as the matrix, combined with a flame retardant composed of antimony trioxide and aluminum hydroxide, to block the combustion path from within the core. Both the flame retardant adhesive rubber layer and the cover layer use decabromodiphenyl ethane flame retardant to form an external flame retardant barrier. For antistatic properties, the impregnation compound adds a quaternary ammonium salt antistatic agent, and the cover layer uses an antistatic system composed of conductive carbon black and antistatic masterbatch, resulting in a surface resistivity as low as 2.3 × 10⁻⁶. 6 Ω, with flame retardant and antistatic properties that are comprehensively superior to the MT / T914 standard, provides all-round safety protection for high-risk scenarios such as underground coal mines.

[0049] 4. This invention utilizes a process route of vacuum impregnation and plasticizing, four-roll calendering and compounding, and vulcanization, resulting in high production efficiency, good product consistency, and compatibility of process parameters with conventional conveyor belt production equipment, facilitating large-scale promotion. The rubber-faced aramid fabric solid-core flame-retardant conveyor belt possesses excellent flexibility and troughing properties, reducing deviation and spillage during conveying. Joint operation is convenient and reliable, reducing subsequent maintenance intensity and costs. Compared to MT / T668 steel cord conveyor belts, this invention's product uses a composite structure of solid aramid fabric and flame-retardant adhesive rubber layer, reducing weight by 30-40%, simplifying installation and maintenance, and eliminating the risk of rust. Simultaneously, raw material costs and production energy consumption are lower, achieving a highly efficient and environmentally friendly replacement for steel cord conveyor belts in high-risk, high-intensity, and high-wear scenarios, demonstrating significant economic value and social benefits. Detailed Implementation

[0050] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, features and effects of the present invention, in conjunction with preferred embodiments, is provided below.

[0051] Example 1: This example provides a rubber-faced aramid fabric solid core flame-retardant conveyor belt, which is prepared through the following steps:

[0052] S1: The warp is made of a blend of 70wt% aramid and 30wt% cotton with a density of 190 threads / 10cm, and the weft is made of a blend of 60wt% nylon and 40wt% cotton with a density of 114 threads / 10cm (60% of the warp density). The warp and weft are woven into a 4-layer integral core using a high-speed warp knitting machine. The tension is controlled at 6N during the knitting process. The weft is plain knitted and interwoven between layers to obtain an integral aramid fabric core.

[0053] S2: By weight, 100 parts of PVC paste resin, 45 parts of dioctyl phthalate (i.e., plasticizer), 10 parts of antimony trioxide (i.e., flame retardant), 20 parts of aluminum hydroxide (i.e., flame retardant), 3 parts of calcium stearate (i.e., stabilizer), 5 parts of quaternary ammonium salt antistatic agent (i.e., antistatic agent), and 15 parts of light calcium carbonate (i.e., filler) are added sequentially to a mixing tank and stirred for 35 minutes at 500 r / min and 45℃. The viscosity is adjusted to 4900 mPa·s to obtain the impregnating compound.

[0054] S3: Place the aramid fabric core and the impregnating material in an impregnation tank and impregnate it under vacuum of -0.08MPa for 4 minutes. After impregnation, send it to a plasticizing oven and plasticize it at 175℃ for 25 minutes. After plasticizing, cool it to room temperature to obtain a plasticized core with an impregnating layer.

[0055] S4: By weight, 65 parts of nitrile rubber and 35 parts of natural rubber are added to a two-roll mill in sequence and plasticized at 95°C for 15 minutes. Then, 20 parts of decabromodiphenyl ethane (i.e., flame retardant), 2 parts of resorcinol resin (i.e., adhesion accelerator), 6 parts of silica (i.e., adhesion accelerator) and 25 parts of carbon black are added and mixed at 115°C for 20 minutes. Then, 1.5 parts of sulfur (i.e., vulcanizing agent) and 1.2 parts of tetramethylthiuram disulfide (i.e., accelerator) are added and finally mixed at 85°C for 8 minutes. After standing at room temperature for 7 hours, the flame-retardant adhesive rubber layer compound is obtained.

[0056] S5: By weight, add 55 parts of natural rubber and 45 parts of styrene-butadiene rubber to a two-roll mill in sequence, and plasticize at 100°C for 18 minutes. Then add 35 parts of carbon black, 25 parts of decabromodiphenyl ethane (i.e., flame retardant), 3 parts of conductive carbon black (i.e., antistatic agent), 1 part of antistatic masterbatch (i.e., antistatic agent), and 8 parts of paraffin oil (i.e., softener), and mix at 120°C for 25 minutes. Then add 2 parts of sulfur (i.e., vulcanizing agent) and 1.5 parts of N-cyclohexyl-2-benzothiazole sulfenamide (i.e., accelerator), and finally grind at 90°C for 10 minutes. Let stand at room temperature for 10 hours to obtain the cover rubber compound.

[0057] S6: The plasticized belt core with the impregnated rubber layer is passed through a four-roll calender. First, the roll gap is adjusted, and the flame-retardant adhesive rubber layer material is hot-melted through the rolls to evenly coat the upper and lower surfaces of the plasticized belt core. During coating, the roll temperature is controlled at 75°C for the upper roll and 70°C for the middle roll, and the calendering speed is 10m / min, forming a flame-retardant adhesive rubber layer with a thickness of 1mm. Then, a cover rubber layer material is coated on the outer surface of the flame-retardant adhesive rubber layer. During coating, the roll temperature is controlled at 85°C for the upper roll and 75°C for the lower roll, and the calendering speed is 10m / min, forming a cover rubber layer with a thickness of 4mm. Through calendering, the cover rubber layer is firmly bonded to the outer surface of the flame-retardant adhesive rubber layer. The roll speed ratio of the four-roll calender is 1:1.3:1.3:1 to ensure that the flame-retardant adhesive rubber layer and the cover rubber layer are tightly bonded and free of air bubbles, resulting in a conveyor belt blank with a belt core, a flame-retardant adhesive rubber layer, and a cover rubber layer.

[0058] S7: The conveyor belt blank is fed into the vulcanizing machine and vulcanized for 30 minutes at a temperature of 150℃ and a pressure of 2.8MPa. After cooling to room temperature, a rubber-faced aramid fabric solid core flame-retardant conveyor belt is obtained.

[0059] The rubber-faced aramid fabric solid-core flame-retardant conveyor belt prepared in Example 1 was tested according to the MT / T914 standard "Flame-retardant conveyor belts with fabric cores for coal mines". The test data are as follows: longitudinal strength 2610 N / mm, transverse strength 1346 N / mm (51.6% of the longitudinal strength), tensile strength of the cover rubber layer 18.2 MPa, elongation at break 425%, and abrasion resistance of the cover rubber layer 118 mm. 3The adhesive strength of the cover layer is 14.8 N / mm, the internal adhesive strength of the core is 16.8 N / mm, and the surface resistivity is 6.2 × 10⁻⁶. 6 Ω, its flame retardant properties and other mechanical properties are superior to the MT / T914 standard.

[0060] Example 2: This example provides a rubber-faced aramid fabric solid core flame-retardant conveyor belt, which is prepared through the following steps:

[0061] S1: The warp is made of a blend of 75wt% aramid and 25wt% cotton with a density of 290 threads / 10cm, and the weft is made of a blend of 65wt% nylon and 35wt% cotton with a density of 191 threads / 10cm (65.9% of the warp density). The warp and weft are woven into a 4-layer integral core using a high-speed warp knitting machine. The tension is controlled at 7N during the knitting process. The weft is plain knitted and interwoven between layers to obtain an integral aramid fabric core.

[0062] S2: By weight, 100 parts of PVC paste resin, 50 parts of dioctyl phthalate (i.e., plasticizer), 12 parts of antimony trioxide (i.e., flame retardant), 24 parts of aluminum hydroxide (i.e., flame retardant), 4 parts of calcium stearate (i.e., stabilizer), 6 parts of quaternary ammonium salt antistatic agent (i.e., antistatic agent) and 18 parts of light calcium carbonate (i.e., filler) are added to a mixing tank in sequence and stirred for 35 minutes at 600 r / min and 48℃. The viscosity is adjusted to 5050 mPa·s to obtain the impregnation compound.

[0063] S3: Place the aramid fabric core and the impregnating material in an impregnation tank and impregnate it under vacuum of -0.07MPa for 5 minutes. After impregnation, send it to a plasticizing oven and plasticize it at 170℃ for 20 minutes. After plasticizing, cool it to room temperature to obtain a plasticized core with an impregnating layer.

[0064] S4: By weight, 68 parts of nitrile rubber and 32 parts of natural rubber are added to a two-roll mill in sequence and plasticized at 98°C for 16 minutes. Then, 22 parts of decabromodiphenyl ethane (i.e., flame retardant), 2.5 parts of resorcinol resin (i.e., adhesion accelerator), 7.5 parts of silica (i.e., adhesion accelerator), and 28 parts of carbon black are added and mixed at 118°C for 22 minutes. Then, 1.7 parts of sulfur (i.e., vulcanizing agent) and 1.3 parts of tetramethylthiuram disulfide (i.e., accelerator) are added and finally mixed at 88°C for 9 minutes. After standing at room temperature for 7.5 hours, the flame-retardant adhesive rubber layer compound is obtained.

[0065] S5: By weight, 58 parts of natural rubber and 42 parts of styrene-butadiene rubber are added to a two-roll mill in sequence and plasticized at 105°C for 20 minutes. Then, 38 parts of carbon black, 28 parts of decabromodiphenyl ethane (i.e., flame retardant), 4 parts of conductive carbon black (i.e., antistatic agent), 1.3 parts of antistatic masterbatch (i.e., antistatic agent), and 9 parts of paraffin oil (i.e., softener) are added and mixed at 125°C for 28 minutes. Then, 2.2 parts of sulfur (i.e., vulcanizing agent) and 1.8 parts of N-cyclohexyl-2-benzothiazole sulfenamide (i.e., accelerator) are added and finally mixed at 95°C for 11 minutes. After standing at room temperature for 11 hours, the cover rubber layer compound is obtained.

[0066] S6: The plasticized belt core with impregnated rubber layer is passed through a four-roll calender. First, the roll gap is adjusted, and the flame-retardant adhesive rubber layer material is hot-melted through the rolls to evenly coat the upper and lower surfaces of the plasticized belt core. During coating, the roll temperature is controlled at 70℃ for the upper roll and 65℃ for the middle roll, and the calendering speed is 5m / min, forming a flame-retardant adhesive rubber layer with a thickness of 1.5mm. Then, a cover rubber layer material is coated on the outer surface of the flame-retardant adhesive rubber layer. During coating, the roll temperature is controlled at 80℃ for the upper roll and 70℃ for the lower roll, and the calendering speed is 5m / min, forming a cover rubber layer with a thickness of 6mm. Through calendering, the cover rubber layer is firmly bonded to the outer surface of the flame-retardant adhesive rubber layer. The roll speed ratio of the four-roll calender is 1:1.3:1.3:1 to ensure that the flame-retardant adhesive rubber layer and the cover rubber layer are tightly bonded and free of air bubbles, resulting in a conveyor belt blank with belt core-flame-retardant adhesive rubber layer-cover rubber layer.

[0067] S7: The conveyor belt blank is fed into the vulcanizing machine and vulcanized for 35 minutes at a temperature of 145℃ and a pressure of 2.5MPa. After cooling to room temperature, a rubber-faced aramid fabric solid core flame-retardant conveyor belt is obtained.

[0068] The rubber-faced aramid fabric solid-core flame-retardant conveyor belt prepared in Example 2 was tested according to the MT / T914 standard "Flame-retardant conveyor belts with fabric cores for coal mines". The test data are as follows: longitudinal strength 4180 N / mm, transverse strength 2132 N / mm (51.5% of the longitudinal strength), tensile strength of the cover rubber layer 18.6 MPa, elongation at break 415%, and abrasion resistance of the cover rubber layer 115 mm. 3 The adhesive strength of the cover layer is 15.5 N / mm, the internal adhesive strength of the core is 17.5 N / mm, and the surface resistivity is 6.2 × 10⁻⁶. 6 Ω, its flame retardant properties and other mechanical properties are superior to the MT / T914 standard.

[0069] Example 3: This example provides a rubber-faced aramid fabric solid core flame-retardant conveyor belt, which is prepared through the following steps:

[0070] S1: The warp is made of a blend of 78wt% aramid and 22wt% cotton with a density of 390 threads / 10cm, and the weft is made of a blend of 68wt% nylon and 32wt% cotton with a density of 265 threads / 10cm (67.9% of the warp density). The warp and weft are woven into a 5-layer integral core using a high-speed warp knitting machine. The tension is controlled at 7.5N during the knitting process. The weft is plain knitted and interwoven between layers to obtain an integral aramid fabric core.

[0071] S2: By weight, 100 parts of PVC paste resin, 55 parts of dioctyl phthalate (i.e., plasticizer), 15 parts of antimony trioxide (i.e., flame retardant), 30 parts of aluminum hydroxide (i.e., flame retardant), 4.5 parts of calcium stearate (i.e., stabilizer), 7 parts of quaternary ammonium salt antistatic agent (i.e., antistatic agent), and 19 parts of light calcium carbonate (i.e., filler) are added sequentially to a mixing tank and stirred for 34 minutes at 700 r / min and 46℃. The viscosity is adjusted to 4980 mPa·s to obtain the impregnating compound.

[0072] S3: Place the aramid fabric core and the impregnating material in an impregnation tank and impregnate it under vacuum at a vacuum degree of -0.09MPa for 5 minutes. After impregnation, send it to a plasticizing oven and plasticize it at 180℃ for 30 minutes. After plasticizing, cool it to room temperature to obtain a plasticized core with an impregnating layer.

[0073] S4: By weight, 62 parts of nitrile rubber and 38 parts of natural rubber are added to a two-roll mill in sequence and plasticized at 100°C for 18 minutes. Then, 24 parts of decabromodiphenyl ethane (i.e., flame retardant), 3 parts of resorcinol resin (i.e., adhesion accelerator), 9 parts of silica (i.e., adhesion accelerator) and 29 parts of carbon black are added and mixed at 120°C for 25 minutes. Then, 1.8 parts of sulfur (i.e., vulcanizing agent) and 1.4 parts of tetramethylthiuram disulfide (i.e., accelerator) are added and finally mixed at 90°C for 10 minutes. After standing at room temperature for 8 hours, the flame-retardant adhesive rubber layer compound is obtained.

[0074] S5: By weight, 60 parts of natural rubber and 40 parts of styrene-butadiene rubber are added sequentially to a two-roll mill and plasticized at 108°C for 22 minutes. Then, 39 parts of carbon black, 29 parts of decabromodiphenyl ethane (i.e., flame retardant), 4.5 parts of conductive carbon black (i.e., antistatic agent), 1.5 parts of antistatic masterbatch (i.e., antistatic agent), and 9.5 parts of paraffin oil (i.e., softener) are added and mixed at 128°C for 30 minutes. Then, 2.4 parts of sulfur (i.e., vulcanizing agent) and 1.9 parts of N-cyclohexyl-2-benzothiazole sulfenamide (i.e., accelerator) are added and finally mixed at 98°C for 12 minutes. After standing at room temperature for 11.5 hours, the cover rubber layer compound is obtained.

[0075] S6: The plasticized belt core with impregnated rubber layer is passed through a four-roll calender. First, the roll gap is adjusted, and the flame-retardant adhesive rubber layer material is hot-melted through the rolls to evenly coat the upper and lower surfaces of the plasticized belt core. During coating, the roll temperature is controlled at 80℃ for the upper roll and 75℃ for the middle roll, and the calendering speed is 15m / min, forming a flame-retardant adhesive rubber layer with a thickness of 1.5mm. Then, a cover rubber layer material is coated on the outer surface of the flame-retardant adhesive rubber layer. During coating, the roll temperature is controlled at 90℃ for the upper roll and 80℃ for the lower roll, and the calendering speed is 15m / min, forming a cover rubber layer with a thickness of 7mm. Through calendering, the cover rubber layer is firmly bonded to the outer surface of the flame-retardant adhesive rubber layer. The roll speed ratio of the four-roll calender is 1:1.3:1.3:1 to ensure that the flame-retardant adhesive rubber layer and the cover rubber layer are tightly bonded and free of air bubbles, resulting in a conveyor belt blank with belt core-flame-retardant adhesive rubber layer-cover rubber layer.

[0076] S7: The conveyor belt blank is fed into the vulcanizing machine and vulcanized for 40 minutes at a temperature of 155℃ and a pressure of 3.0MPa. After cooling to room temperature, a rubber-faced aramid fabric solid core flame-retardant conveyor belt is obtained.

[0077] The rubber-faced aramid fabric solid-core flame-retardant conveyor belt prepared in Example 3 was tested according to the MT / T914 standard "Flame-retardant conveyor belts with fabric cores for coal mines". The test data are as follows: longitudinal strength 5560 N / mm, transverse strength 2902 N / mm (51.5% of the longitudinal strength), tensile strength of the cover rubber layer 19.1 MPa, elongation at break 409%, and abrasion resistance of the cover rubber layer 115 mm. 3 The adhesive strength of the cover layer is 16.2 N / mm, the internal adhesive strength of the core is 18.2 N / mm, and the surface resistivity is 4.7 × 10⁻⁶. 6 Ω, its flame retardant properties and other mechanical properties are superior to the MT / T914 standard.

[0078] Example 4: This example provides a rubber-faced aramid fabric solid core flame-retardant conveyor belt, which is prepared through the following steps:

[0079] S1: The warp is made of a blend of 80wt% aramid and 20wt% cotton with a density of 530 threads / 10cm, and the weft is made of a blend of 70wt% nylon and 30wt% cotton with a density of 371 threads / 10cm (70% of the warp density). The warp and weft are woven into a 5-layer integral core using a high-speed warp knitting machine. The tension is controlled at 8N during the knitting process. The weft is plain knitted and interwoven between layers to obtain an integral aramid fabric core.

[0080] S2: By weight, 100 parts of PVC paste resin, 60 parts of dioctyl phthalate (i.e., plasticizer), 17 parts of antimony trioxide (i.e., flame retardant), 34 parts of aluminum hydroxide (i.e., flame retardant), 5 parts of calcium stearate (i.e., stabilizer), 8 parts of quaternary ammonium salt antistatic agent (i.e., antistatic agent), and 20 parts of light calcium carbonate (i.e., filler) are added sequentially to a mixing tank and stirred for 30 minutes at 800 r / min and 50℃. The viscosity is adjusted to 5020 mPa·s to obtain the impregnating compound.

[0081] S3: Place the aramid fabric core and the impregnating material in an impregnation tank and impregnate it under vacuum at a vacuum degree of -0.09MPa for 5 minutes. After impregnation, send it to a plasticizing oven and plasticize it at 180℃ for 30 minutes. After plasticizing, cool it to room temperature to obtain a plasticized core with an impregnating layer.

[0082] S4: By weight, 70 parts of nitrile rubber and 30 parts of natural rubber are added to a two-roll mill in sequence and plasticized at 102°C for 20 minutes. Then, 25 parts of decabromodiphenyl ethane (i.e., flame retardant), 3.5 parts of resorcinol resin (i.e., adhesion accelerator), 10.5 parts of silica (i.e., adhesion accelerator) and 30 parts of carbon black are added and mixed at 122°C for 28 minutes. Then, 2.0 parts of sulfur (i.e., vulcanizing agent) and 1.5 parts of tetramethylthiuram disulfide (i.e., accelerator) are added and finally mixed at 92°C for 11 minutes. After standing at room temperature for 8 hours, the flame-retardant adhesive rubber layer compound is obtained.

[0083] S5: By weight, 60 parts of natural rubber and 40 parts of styrene-butadiene rubber are added to a two-roll mill in sequence and plasticized at 110°C for 25 minutes. Then, 40 parts of carbon black, 30 parts of decabromodiphenyl ethane (i.e., flame retardant), 5 parts of conductive carbon black (i.e., antistatic agent), 1.7 parts of antistatic masterbatch (i.e., antistatic agent), and 10 parts of paraffin oil (i.e., softener) are added and mixed at 130°C for 32 minutes. Then, 2.5 parts of sulfur (i.e., vulcanizing agent) and 2 parts of N-cyclohexyl-2-benzothiazole sulfenamide (i.e., accelerator) are added and finally mixed at 100°C for 13 minutes. After standing at room temperature for 12 hours, the cover rubber layer compound is obtained.

[0084] S6: The plasticized belt core with impregnated rubber layer is passed through a four-roll calender. First, the roll gap is adjusted, and the flame-retardant adhesive rubber layer material is hot-melted through the rolls to evenly coat the upper and lower surfaces of the plasticized belt core. During coating, the roll temperature is controlled at 80℃ for the upper roll and 75℃ for the middle roll, and the calendering speed is 15m / min, forming a flame-retardant adhesive rubber layer with a thickness of 2mm. Then, a cover rubber layer material is coated on the outer surface of the flame-retardant adhesive rubber layer. During coating, the roll temperature is controlled at 90℃ for the upper roll and 80℃ for the lower roll, and the calendering speed is 15m / min, forming a cover rubber layer with a thickness of 8mm. Through calendering, the cover rubber layer is firmly bonded to the outer surface of the flame-retardant adhesive rubber layer. The roll speed ratio of the four-roll calender is 1:1.3:1.3:1 to ensure that the flame-retardant adhesive rubber layer and the cover rubber layer are tightly bonded and free of air bubbles, resulting in a conveyor belt blank with belt core-flame-retardant adhesive rubber layer-cover rubber layer.

[0085] S7: The conveyor belt blank is fed into the vulcanizing machine and vulcanized for 45 minutes at a temperature of 155℃ and a pressure of 3.0MPa. After cooling to room temperature, a rubber-faced aramid fabric solid core flame-retardant conveyor belt is obtained.

[0086] The rubber-faced aramid fabric solid-core flame-retardant conveyor belt prepared in Example 4 was tested according to the MT / T914 standard "Flame-retardant conveyor belts with fabric cores for coal mines". The test data are as follows: longitudinal strength 7680 N / mm, transverse strength 3902 N / mm (50.8% of the longitudinal strength), tensile strength of the cover rubber layer 19.8 MPa, elongation at break 406%, and abrasion resistance of the cover rubber layer 105 mm. 3 The adhesive strength of the cover layer is 17.3 N / mm, the internal adhesive strength of the core is 19.5 N / mm, and the surface resistivity is 2.3 × 10⁻⁶. 6 Ω, its flame retardant properties and other mechanical properties are superior to the MT / T914 standard.

[0087] Comparative Example 1: This comparative example provides a solid aramid fabric flame-retardant conveyor belt, which is prepared through the following steps:

[0088] S1: The warp is made of a blend of 70wt% aramid and 30wt% polyester with a density of 190 threads / 10cm, and the weft is made of a blend of 60wt% nylon and 40wt% polyester with a density of 114 threads / 10cm (60% of the warp density). The warp and weft are woven into a 3-layer integral core using a high-speed warp knitting machine. The tension is controlled at 6N during the knitting process. The weft is plain knitted and the layers are bonded only by dip-ins without interlacing, resulting in an integral aramid fabric core.

[0089] S2: By weight, add 100 parts of polyurethane adhesive, 15 parts of APP (ammonium polyphosphate), 10 parts of zinc borate, 1.5 parts of silane coupling agent KH-550, and 15 parts of light calcium carbonate to a mixing tank in sequence, stir for 35 minutes at 500 r / min and 45℃, and adjust the viscosity to 4900 mPa·s to obtain the impregnation adhesive.

[0090] S3: Place the aramid fabric core and the impregnating material in an impregnation tank and impregnate it under vacuum of -0.08MPa for 4 minutes. After impregnation, send it to a plasticizing oven and cure it at 120℃ for 30 minutes. Cool it to room temperature to obtain a plasticized core with an impregnating layer.

[0091] S4: By weight, 60 parts of EVA (ethylene-vinyl acetate copolymer), 40 parts of styrene-butadiene rubber, 5 parts of red phosphorus, 20 parts of magnesium hydroxide, 8 parts of melamine cyanurate, 35 parts of carbon black, 2 parts of sulfur, 1.5 parts of N-cyclohexyl-2-benzothiazole sulfenamide, and 8 parts of paraffin oil are added to a two-roll mill in sequence. The mixture is plasticized at 100°C for 18 min, mixed for 25 min, and finally mixed for 10 min. After being left to stand at room temperature for 10 h, the topcoat rubber compound is obtained.

[0092] S5: The plasticized belt core with impregnated rubber layer is passed through a four-roll calender, and the cover rubber layer is directly applied to the upper and lower surfaces of the plasticized belt core. During the application, the roller temperature is controlled at 85°C for the upper roller and 75°C for the lower roller, and the calendering speed is 10m / min to form a cover rubber layer with a thickness of 5mm. The roller speed ratio of the four-roll calender is 1:1.3:1.3:1, to obtain the conveyor belt blank.

[0093] S6: The conveyor belt blank is fed into the vulcanizing machine and vulcanized for 30 minutes at a temperature of 150℃ and a pressure of 2.8MPa. After cooling to room temperature, an aramid fabric solid core flame-retardant conveyor belt is obtained.

[0094] The aramid fabric solid core flame-retardant conveyor belt prepared in Example 4 was tested according to the MT / T914 standard "Flame-retardant conveyor belts with fabric cores for coal mines". The test data are as follows:

[0095] The conveyor belts prepared in Examples 1-4 and Comparative Example 1 were tested according to the MT / T914 standard "Flame-retardant conveyor belts with fabric cores for coal mines". The test results are as follows: longitudinal strength 2250 N / mm, transverse strength 923 N / mm, tensile strength of the cover rubber layer 14.8 MPa, elongation at break 320%, abrasion resistance of the cover rubber layer 205 mm³, adhesion strength between the cover rubber layer and the belt core 6.5 N / mm, internal adhesion strength of the belt core 8.2 N / mm, and surface resistivity 3.8 × 10⁻⁶. 8 Ω, its flame retardant performance only meets the minimum requirements of the MT / T914 standard.

[0096] The specific test results are shown in the table below:

[0097] Table 1 Performance Test Overview

[0098] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Longitudinal strength (N / mm) 2610 4180 5560 7680 2250 Lateral strength (N / mm) 1346 2132 2902 3902 923 Tensile strength of the adhesive layer (MPa) 18.2 18.6 19.1 19.8 14.8 Elongation at break (%) 425 415 409 406 320 <![CDATA[Wear loss of the cover rubber layer (mm 3 )]]> 118 115 115 105 205 Adhesive strength of the cover layer (N / mm) 14.8 15.5 16.2 17.3 6.5 Internal bonding strength of the strip core (N / mm) 16.8 17.5 18.2 19.5 8.2 Surface resistivity (Ω) <![CDATA[6.2×10 6 ]]> <![CDATA[6.2×10 6 ]]> <![CDATA[4.7×10 6 ]]> <![CDATA[2.3×10 6 ]]> <![CDATA[3.8×10 8 ]]>

[0099] As shown in Table 1, the longitudinal and transverse strengths of Examples 1-4 are higher than those of Comparative Example 1. This may be because the examples use a 4-5 layer aramid / nylon / cotton blended integral core. The aramid content in the warp yarn is 70-80% to ensure high longitudinal strength, and the nylon / cotton ratio in the weft yarn is 60-70:30-40 with a density of 60-70% of that in the warp yarn. Combined with interlayer interlacing fixation and 5-8N weaving tension control, the structural stability is stronger.

[0100] As shown in Table 1, the tensile strength, elongation at break, and abrasion loss of the cover rubber layer in Examples 1-4 are all higher than those in Comparative Example 1. This may be because the cover rubber layer in the examples uses a blend system of natural rubber and styrene-butadiene rubber (50-60:40-50), combined with 30-40 parts of high abrasion-resistant carbon black and paraffin oil softener. By precisely controlling the plasticizing, mixing, and final mixing temperatures, the rubber compound is evenly dispersed and fully crosslinked.

[0101] As shown in Table 1, the adhesive strength of the cover layer and the adhesive strength inside the belt core of Examples 1-4 are higher than those of Comparative Example 1. This may be because a flame-retardant adhesive rubber layer is added to the aramid fabric solid core flame-retardant conveyor belt with rubber surface. The system uses a blend of nitrile rubber and natural rubber, combined with resorcinol resin and silica composite adhesive accelerator, and achieves tight bonding through a four-roll calendering two-step adhesive bonding process, resulting in higher adhesive strength.

[0102] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0103] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A rubber-faced aramid fabric solid core flame-retardant conveyor belt, characterized in that, From the inside out, the fabric consists of an integral aramid fabric core, an impregnated adhesive layer, a flame-retardant adhesive rubber layer, and a cover adhesive layer. The integral aramid fabric core is a 4-5 layer woven structure of aramid, nylon, and cotton fibers. The warp is composed of 70-80 wt% aramid and 20-30 wt% cotton blended fibers, and the weft is composed of 60-70 wt% nylon and 30-40 wt% cotton blended fibers. The impregnated adhesive layer is formed by impregnating and plasticizing an impregnating adhesive material, the viscosity of which is 4800-5100 mPa•s; The adhesive strength of the covering layer is ≥14N / mm, and the abrasion resistance is ≤120mm. 3 ; The overall adhesive strength of the aramid fabric core is ≥15N / mm.

2. The rubber-faced aramid fabric solid core flame-retardant conveyor belt according to claim 1, characterized in that, The warp density is 180-200 warp threads / 10cm, with a strength of 2500 N / mm; the warp density is 280-300 warp threads / 10cm, with a strength of 4000 N / mm; the warp density is 380-400 warp threads / 10cm, with a strength of 5400 N / mm; the warp density is 520-540 warp threads / 10cm, with a strength of 7500 N / mm; and the weft density is 60-70% of the corresponding warp density.

3. The rubber-faced aramid fabric solid core flame-retardant conveyor belt according to claim 1, characterized in that, The impregnating compound comprises the following components by weight: 100 parts PVC paste resin, 40-60 parts plasticizer, 30-50 parts flame retardant, 2-5 parts stabilizer, 3-8 parts antistatic agent, and 10-20 parts filler; The plasticizer is a phthalate plasticizer; The flame retardant is composed of antimony trioxide and aluminum hydroxide in a mass ratio of 1:

2. The stabilizer is a metal soap stabilizer; The antistatic agent is a quaternary ammonium salt type antistatic agent; The filler is an inorganic filler.

4. The rubber-faced aramid fabric solid core flame-retardant conveyor belt according to claim 1, characterized in that, The flame-retardant adhesive rubber layer comprises the following components by weight: The composition includes 60-70 parts of nitrile rubber, 30-40 parts of natural rubber, 15-25 parts of flame retardant, 5-10 parts of adhesion accelerator, 20-30 parts of carbon black, 1-2 parts of vulcanizing agent, and 0.8-1.5 parts of accelerator. The flame retardant is an aromatic bromide among bromine-based flame retardants; The adhesion promoter is composed of resorcinol resin and fumed silica in a mass ratio of 1:

3. The accelerator is a thiuram-based accelerator.

5. The rubber-faced aramid fabric solid core flame-retardant conveyor belt according to claim 1, characterized in that, The adhesive layer, by weight, comprises the following components: Natural rubber 50-60 parts, styrene-butadiene rubber 40-50 parts, carbon black 30-40 parts, flame retardant 20-30 parts, antistatic agent 5-10 parts, vulcanizing agent 1.5-2.5 parts, accelerator 1-2 parts, and softener 5-10 parts; The flame retardant is an aromatic bromide among bromine-based flame retardants; The antistatic agent is composed of conductive carbon black and antistatic masterbatch mixed at a mass ratio of 3:

1. The accelerator is a sulfenamide accelerator; The softener is a mineral oil-based softener.

6. A method for manufacturing a rubber-faced aramid fabric solid-core flame-retardant conveyor belt as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Use a high-speed warp knitting machine to knit the warp and weft into a 4-5 layer integral core. Control the tension at 5-8N during the knitting process and use interlayer interlacing to fix it, so as to obtain an integral aramid fabric core. Step 2: Place the aramid fabric core and the impregnating material in the impregnation tank, vacuum impregnate and plasticize to obtain a plasticized core with an impregnating layer; Step 3: After plasticizing nitrile rubber and natural rubber, add carbon black, flame retardant and adhesion accelerator and mix. Finally add vulcanizing agent and accelerator and finish mixing. Let stand for 6-8 hours to obtain flame retardant adhesive rubber layer compound. Step 4: After plasticizing natural rubber and styrene-butadiene rubber, add carbon black, flame retardant, antistatic agent and softener and mix. Finally, add vulcanizing agent and accelerator and finish mixing. Let stand for 8-12 hours to obtain the cover rubber layer compound. Step 5: Use a four-roll calender to perform two-step adhesive application. First, apply flame-retardant adhesive rubber to both the upper and lower surfaces of the plasticized belt core, and calender to form a flame-retardant adhesive rubber layer. Then, apply a cover adhesive layer to the outer surface of the flame-retardant adhesive rubber layer, and calender to form a cover adhesive layer, thus obtaining the conveyor belt blank. Step 6: Vulcanize the conveyor belt blank at a temperature of 145-155℃ and a pressure of 2.5-3.0MPa for 30-40 minutes, then cool it to obtain a rubber-faced aramid fabric solid core flame-retardant conveyor belt.

7. The method for manufacturing a rubber-faced aramid fabric solid core flame-retardant conveyor belt according to claim 6, characterized in that, The vacuum degree of vacuum impregnation in step two is -0.07 to -0.09 MPa, and the vacuum impregnation time is 4-5 min; The plasticizing temperature is 170-180℃, and the time is 20-30 minutes.

8. The method for manufacturing a rubber-faced aramid fabric solid-core flame-retardant conveyor belt according to claim 6, characterized in that, In step five, when applying the flame-retardant adhesive rubber layer, the temperature of the upper roller is 70-80℃ and the temperature of the middle roller is 65-75℃. When applying the adhesive layer, the temperature of the upper roller is 80-90℃ and the temperature of the lower roller is 70-80℃. The rolling speed is 5-15 m / min; The roller speed ratio of the four-roll calender is 1:1.3:1.3:

1.

9. A method for manufacturing a rubber-faced aramid fabric solid-core flame-retardant conveyor belt according to claim 6, characterized in that, The thickness of the flame-retardant adhesive rubber layer mentioned in step four is 1-2 mm.

10. A method for manufacturing a rubber-faced aramid fabric solid-core flame-retardant conveyor belt according to claim 6, characterized in that, The thickness of the adhesive layer mentioned in step four is 4-8 mm.