High-temperature-resistant flame-retardant chlorinated polyvinyl chloride plastic conveying belt

Abstract

The invention relates to the technical field of rubber conveying belts, and discloses a high-temperature-resistant flame-retardant chlorinated polyvinyl chloride plastic conveying belt. The conveyor belt aims at solving the problems that an existing rubber-based conveyor belt is poor in thermal stability, low in flame retardant efficiency and rapid in mechanical property attenuation in a high-temperature, open fire or thermal radiation environment. The tensile body is composed of an upper covering layer, a lower covering layer and a tensile body core layer. The covering layer is formed by blending and extruding chlorinated polyvinyl chloride resin, a heat stabilizer, a flame retardant synergist, a smoke suppressant, a plasticizer, a lubricant and an inorganic filler; and the core layer is formed by compounding and hot-pressing plasma-treated aramid fabric and chlorinated polyvinyl chloride dipping slurry. Through multi-component collaborative design, the conveyor belt keeps structural integrity and mechanical properties under long-term thermal exposure at 200 DEG C, the limit oxygen index is larger than or equal to 38% and reaches the UL94 V-0 level, and the conveyor belt is free of molten drops, low in smoke and low in toxicity, can be subjected to continuous thermoplastic forming and does not need vulcanization.

Description

Technical Field

[0001] This invention relates to the field of rubber conveyor belt technology, specifically to a high-temperature resistant and flame-retardant chlorinated polyvinyl chloride plastic conveyor belt. Background Technology

[0002] Traditionally, rubber conveyor belts have long held a dominant position due to their excellent elasticity, wear resistance, and impact resistance. Their typical manufacturing process usually includes mixing, calendering, molding, and vulcanization. Natural or synthetic rubber is blended with carbon black, vulcanizing agents, accelerators, antioxidants, and flame-retardant fillers to form a cover rubber and core layer structure with specific mechanical and functional properties. This is then subjected to high-temperature vulcanization and cross-linking curing, ultimately resulting in a finished conveyor belt with a certain flame-retardant rating and operating temperature range.

[0003] To meet basic flame-retardant requirements, existing rubber conveyor belts often employ inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, or halogen-antimony composite flame-retardant systems. While these solutions can improve the limited oxygen index and suppress flame spread under normal operating conditions, they are fundamentally limited by the thermal stability bottleneck of the rubber polymer backbone. When rubber materials are continuously exposed to high-temperature environments above 150°C, the molecular chains are prone to thermo-oxidative aging, cross-linking network degradation, or over-vulcanization, leading to a sharp drop in tensile strength, surface cracking, and even interlayer delamination. Furthermore, the manufacturing process of rubber conveyor belts relies on high-temperature, high-pressure vulcanization, which is energy-intensive, time-consuming, and difficult to control the uniformity of vulcanization, easily causing fluctuations in product performance. The root cause lies in the fact that improving the performance of rubber materials essentially involves a trade-off between "flame-retardant additive content" and "matrix mechanical properties." This inherent contradiction exposes insurmountable technical limitations when facing next-generation high-reliability, high-safety conveyor scenarios.

[0004] Therefore, how to overcome the limitations of the thermal and flammability properties of traditional rubber matrices and develop a new type of conveyor belt material system that combines excellent high-temperature stability, inherent flame retardancy, good mechanical strength, and processing feasibility has become a key challenge and an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] This invention provides a high-temperature resistant, flame-retardant chlorinated polyvinyl chloride (PVC) plastic conveyor belt, aiming to solve the technical problems of existing rubber-based conveyor belts, which suffer from safety hazards and limited service life due to insufficient material thermal stability, low flame-retardant efficiency, and rapid degradation of mechanical properties under high-temperature, open-flame, or heat radiation environments. To achieve the above-mentioned objective, this invention employs a thermoplastic polymer system based on chlorinated polyvinyl chloride resin. By constructing a multi-level synergistic reinforcement structure and introducing a specific ratio of functional additives, it achieves structural integrity, inherent flame retardancy, and dynamic mechanical stability of the material under long-term heat exposure conditions above 200°C without relying on vulcanization crosslinking.

[0006] The high-temperature resistant and flame-retardant chlorinated polyvinyl chloride (PVC) plastic conveyor belt consists of an upper cover layer, a lower cover layer, and a tensile core layer located between the two. Both the upper and lower cover layers are formed by melt extrusion molding of chlorinated polyvinyl chloride resin, heat stabilizer, flame retardant synergist, smoke suppressant, plasticizer, lubricant, and inorganic filler in a certain proportion. The tensile core layer is formed by hot pressing a composite aramid fiber fabric treated with surface plasma and a chlorinated polyvinyl chloride resin-based impregnated slurry.

[0007] Furthermore, the chlorinated polyvinyl chloride resin has a chlorine content of 65 to 72% by weight, a Vicat softening point of not less than 110°C, and a tensile strength retention rate of not less than 85% of the original value after aging in hot air at 200°C for 168 hours. The heat stabilizer is composed of an organotin compound and a rare earth composite oxide in a mass ratio of 3:1, wherein the organotin compound is dibutyltin dilaurate, and the rare earth composite oxide is a solid solution of cerium oxide and lanthanum oxide in a molar ratio of 4:1. This heat stabilizer system effectively slows down the thermal degradation process of the main chain by capturing HCl generated in the dehydrochlorination reaction and inhibiting the formation of polyene sequences.

[0008] In a preferred embodiment of the present invention, the flame retardant synergist is a composite of melamine polyphosphate and zinc borate in a mass ratio of 2:1; the smoke suppressant is a mixture of ammonium molybdate and zinc stannate in a mass ratio of 1:1. Melamine polyphosphate decomposes upon heating to produce non-combustible gases and promotes char formation, while zinc borate melts at high temperatures and covers the material surface to form a glassy barrier. The synergistic effect of these two substances significantly increases the limiting oxygen index and inhibits flame propagation. Ammonium molybdate catalyzes the charring reaction to reduce smoke density, while zinc stannate reduces the release of toxic gases through a free radical adsorption mechanism.

[0009] The plasticizer is a compound system of trioctyl trimellitate and epoxidized soybean oil in a mass ratio of 4:1. Trioctyl trimellitate provides the main plasticizing effect to maintain the flexibility of the material, while epoxidized soybean oil has both auxiliary plasticizing and thermal stabilizing functions. Its epoxy groups can undergo an addition reaction with the removed HCl to further inhibit the degradation chain reaction. The lubricant is a mixture of calcium stearate and polyethylene wax in a mass ratio of 1:2, used to improve melt flowability and prevent melt fracture during extrusion.

[0010] The inorganic filler is a composite filler of calcined kaolin treated with a surface silane coupling agent and hollow glass microspheres, with a mass ratio of 3:1. The calcined kaolin improves the material's rigidity and dimensional stability, while the hollow glass microspheres reduce thermal conductivity through their internal closed-cell structure. Together, they achieve both thermal insulation and mechanical reinforcement. The silane coupling agent is γ-aminopropyltriethoxysilane, which, after hydrolysis, condenses with the hydroxyl groups on the filler surface to form covalent bonds, and simultaneously forms physical entanglement with the chlorinated polyvinyl chloride molecular chains, significantly improving the interfacial bonding strength.

[0011] The aramid fiber fabric in the tensile core layer is a para-aramid plain weave fabric with a warp and weft tensile strength of not less than 2000 N / mm² and an initial modulus of not less than 70 GPa. The surface plasma treatment uses an atmospheric pressure dielectric barrier discharge device to continuously treat the fabric surface for 5 to 10 seconds under a nitrogen atmosphere, introducing nitrogen-containing polar groups into the fiber surface and improving its interfacial adhesion energy with chlorinated polyvinyl chloride resin. The impregnation slurry is prepared from chlorinated polyvinyl chloride resin emulsion, acrylate adhesive accelerator, and deionized water at a solid content of 40%. The acrylate adhesive accelerator is a glycidyl methacrylate-butyl acrylate copolymer, whose epoxy functional groups undergo a ring-opening reaction with the amino groups on the aramid surface to form a chemically bonded interface.

[0012] The upper and lower cover layers are melted and plasticized using a twin-screw extruder, then extruded into sheets through a T-die. These sheets are then laminated with a pre-impregnated and semi-dried tensile core layer and fed into a continuous calendering and laminating unit. Hot-pressing is performed at 160-180°C and 0.8-1.2 MPa pressure. Finally, the sheets are cooled, shaped, trimmed, and wound to obtain the finished conveyor belt. The calendering and laminating process employs a three-roll reverse calendering configuration to ensure no air gaps remain between the cover layer and the core layer and that the interfacial shear strength is not less than 8 N / mm.

[0013] Furthermore, the overall structure of the conveyor belt achieves UL94 V-0 rating in vertical combustion tests, with a limiting oxygen index of not less than 38%, a tensile strength retention rate of not less than 80% after aging in hot air at 200°C for 500 hours, a tear strength of not less than 60 kN / m, and no molten droplets during combustion with a smoke density rating of less than 300. In roller bending fatigue tests, the conveyor belt shows no visible cracks on its surface after 100,000 cycles, and its interlaminar peel strength is not less than 4.5 N / mm.

[0014] As another technical feature of this invention, the chlorinated polyvinyl chloride resin does not undergo a cross-linking reaction during processing. Its molding relies entirely on the thermoplastic melt flow and cooling solidification mechanism. Therefore, it can be manufactured using a continuous extrusion-calendering integrated process, eliminating the need for the intermittent flat vulcanizing equipment required for traditional rubber conveyor belts, significantly shortening the production cycle and reducing energy consumption. Furthermore, since the material system does not contain a vulcanization network, it does not exhibit over-vulcanization or reversion during high-temperature service, and its mechanical property degradation shows a linear and controllable trend.

[0015] The thickness of the conveyor belt ranges from 4 to 12 mm, with the upper cover layer being 1.5 to 4 mm thick, the lower cover layer being 1 to 3 mm thick, and the tensile core layer being 2 to 6 mm thick. The thickness of each layer is precisely matched and designed according to the tension of the conveying system, the impact load of the material, and the ambient temperature gradient to ensure that the stress distribution of the overall structure is uniform under high-temperature conditions and to avoid early failure caused by local thermal stress concentration.

[0016] Furthermore, the conveyor belt edge is provided with a heat-sealed edge structure, which is made of chlorinated polyvinyl chloride sheet of the same material and wrapped around both sides of the belt body by high-frequency heat sealing process to form a continuous sealing layer, preventing moisture, dust or corrosive media from penetrating along the interlayer interface, thereby improving long-term reliability in humid, dusty or chemically corrosive environments.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0018] 1. The high-temperature resistant and flame-retardant chlorinated polyvinyl chloride (PVC) plastic conveyor belt of this invention fundamentally avoids the inherent constraints of the rubber matrix in the triangular contradiction between high temperature, flame retardancy, and mechanical properties through material system reconstruction and integrated structural-functional design. Chlorinated polyvinyl chloride resin itself possesses self-extinguishing properties due to its high chlorine content. Combined with a multi-component synergistic flame-retardant system and a heat-insulating filler network, it achieves inherent flame retardancy and low smoke and low toxicity. Precise formulation of heat stabilizers and plasticizers ensures the stability of the molecular chains and the retention of flexibility under long-term heat exposure above 200℃. The interfacial chemical bonding design between the aramid-reinforced core layer and the thermoplastic cover layer ensures structural integrity and fatigue resistance under dynamic loads. The overall manufacturing process abandons the energy-intensive vulcanization step and adopts a fully thermoplastic continuous molding route, combining industrial feasibility with consistent performance.

[0019] 2. The conveyor belt is suitable for industrial scenarios with continuous heat radiation, occasional fires, or strict fire prevention regulations, such as metallurgical sinter cooling and conveying, cement clinker transfer, power plant boiler bottom ash conveying, and chemical high-temperature material transfer. It can operate stably for a long time in an ambient temperature of 180 to 220℃, and can quickly self-extinguish and suppress the spread of fire in the event of a sudden fire, meeting the comprehensive requirements of modern high-reliability material conveying systems for safety, durability, and environmental protection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall process of the conveyor belt of the present invention.

[0021] Figure 2 This is a schematic diagram of the material composition of the upper and lower cover layers of the conveyor belt described in this invention and the multi-level synergistic reinforcement process.

[0022] Figure 3 This is a schematic diagram of the process of the composite interface between plasma-treated aramid fiber fabric and chlorinated polyvinyl chloride resin-based impregnation slurry in the tensile core layer of the present invention.

[0023] Figure 4 This is a schematic diagram of the hot pressing bonding process of the conveyor belt in the continuous calendering composite unit of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a high-temperature resistant and flame-retardant chlorinated polyvinyl chloride (PVC) plastic conveyor belt, the overall structure of which consists of an upper cover layer, a lower cover layer, and a tensile core layer located between the two. The layers are formed into an integrated belt structure through a hot-pressing composite process, possessing structural integrity, inherent flame retardancy, and dynamic mechanical stability under long-term heat exposure conditions above 200°C. The technical solution of this invention will be described in detail below with reference to specific embodiments.

[0026] Both the upper and lower cover layers are formed by melt extrusion molding of chlorinated polyvinyl chloride resin, heat stabilizer, flame retardant synergist, smoke suppressant, plasticizer, lubricant, and inorganic filler in a predetermined ratio. The chlorinated polyvinyl chloride resin has a chlorine content of 65 to 72% by weight, a Vicat softening point of not less than 110°C, and a tensile strength retention rate of not less than 85% of the original value after aging in hot air at 200°C for 168 hours. This resin serves as the main polymer substrate, providing fundamental mechanical properties and self-extinguishing characteristics.

[0027] Furthermore, the heat stabilizer is composed of an organotin compound and a rare earth composite oxide in a mass ratio of 3:1. The organotin compound is dibutyltin dilaurate, and the rare earth composite oxide is a solid solution of cerium oxide and lanthanum oxide in a molar ratio of 4:1. This heat stabilizer system effectively slows down the thermal degradation process of the main chain by capturing HCl generated during the dehydrochlorination reaction and inhibiting the formation of polyene sequences during processing and service.

[0028] In a preferred embodiment of the present invention, the flame retardant synergist is a composite of melamine polyphosphate and zinc borate in a mass ratio of 2:1. Melamine polyphosphate decomposes upon heating to produce non-combustible gases and promotes char formation, while zinc borate melts at high temperatures and covers the material surface to form a glassy barrier. The synergistic effect of the two significantly increases the limiting oxygen index and inhibits flame propagation. The smoke suppressant is a mixture of ammonium molybdate and zinc stannate in a mass ratio of 1:1. Ammonium molybdate catalyzes the charring reaction to reduce smoke density, while zinc stannate reduces the release of toxic gases through free radical adsorption.

[0029] The plasticizer is a compound system of trioctyl trimellitate and epoxidized soybean oil in a mass ratio of 4:1. Trioctyl trimellitate provides the main plasticizing effect to maintain the flexibility of the material, while epoxidized soybean oil has both auxiliary plasticizing and thermal stabilizing functions. Its epoxy groups can undergo an addition reaction with the removed HCl, further inhibiting the degradation chain reaction. The lubricant is a mixture of calcium stearate and polyethylene wax in a mass ratio of 1:2, used to improve melt flowability and prevent melt fracture during extrusion.

[0030] The inorganic filler is a composite filler of calcined kaolin treated with a surface silane coupling agent and hollow glass microspheres, with a mass ratio of 3:1. Calcined kaolin improves the material's rigidity and dimensional stability, while the hollow glass microspheres reduce thermal conductivity through their internal closed-cell structure. Together, they achieve both thermal insulation and mechanical reinforcement. The silane coupling agent is γ-aminopropyltriethoxysilane, which, after hydrolysis, condenses with the hydroxyl groups on the filler surface to form covalent bonds, and simultaneously forms physical entanglement with the chlorinated polyvinyl chloride molecular chains, significantly improving the interfacial bonding strength.

[0031] In one specific embodiment, the upper cover layer formulation, by weight, comprises: 100 parts chlorinated polyvinyl chloride resin, 3.2 parts heat stabilizer, 15 parts flame retardant synergist, 8 parts smoke suppressant, 12 parts plasticizer, 1.8 parts lubricant, and 20 parts inorganic filler. The lower cover layer formulation, by weight, comprises: 100 parts chlorinated polyvinyl chloride resin, 3.0 parts heat stabilizer, 14 parts flame retardant synergist, 7.5 parts smoke suppressant, 11 parts plasticizer, 1.6 parts lubricant, and 18 parts inorganic filler. The difference between the upper and lower cover layer formulations mainly stems from the different requirements of the service environment for abrasion resistance and impact resistance. The upper cover layer, which is in direct contact with the material, requires a higher filler content to improve surface hardness and heat resistance.

[0032] The tensile core layer is formed by hot-pressing a composite aramid fiber fabric treated with surface plasma and a chlorinated polyvinyl chloride resin-based impregnating slurry. The aramid fiber fabric is a para-aramid plain weave fabric with a warp and weft tensile strength of not less than 2000 N / mm² and an initial modulus of not less than 70 GPa. The surface plasma treatment uses an atmospheric pressure dielectric barrier discharge device to continuously treat the fabric surface for 5 to 10 seconds in a nitrogen atmosphere, introducing nitrogen-containing polar groups onto the fiber surface and improving its interfacial adhesion energy with the chlorinated polyvinyl chloride resin.

[0033] The impregnation slurry is formulated from chlorinated polyvinyl chloride resin emulsion, acrylate adhesive accelerator, and deionized water at a solid content of 40%. The acrylate adhesive accelerator is a glycidyl methacrylate-butyl acrylate copolymer, whose epoxy functional groups undergo a ring-opening reaction with the amino groups on the aramid surface to form a chemical bonding interface. The impregnation process uses a two-roller impregnation machine, controlling the fabric belt speed at 2 meters / minute and the slurry temperature at 35°C. After impregnation, the fabric has an adhesive content of 25±2% by weight. Subsequently, it enters an 80°C hot air drying oven for semi-drying treatment, allowing the moisture to evaporate to a residual amount of less than 1.5%.

[0034] The upper and lower cover layers are melt-plasticized separately using a twin-screw extruder and then extruded into sheets through a T-die. The temperature zones of the twin-screw extruder are set as follows: feeding section 120℃, compression section 145℃, metering section 165℃, and die 170℃; the screw speed is 120 rpm, and the vacuum degree is maintained at -0.08 MPa to remove volatiles. The extruded sheet thicknesses are 2.5 mm for the upper cover layer and 2.0 mm for the lower cover layer, and the surface roughness Ra is controlled within 3.2 micrometers to ensure the quality of the subsequent bonding interface.

[0035] The semi-dried tensile core layer and the upper and lower cover layers are fed into a continuous calendering and laminating unit for hot pressing and bonding under a temperature range of 160 to 180°C and a pressure of 0.8 to 1.2 MPa. The calendering and laminating process employs a three-roll reverse calendering configuration: upper roll temperature 175°C, middle roll 170°C, and lower roll 165°C; linear pressure 1.0 MPa; and belt speed 3 m / min. This process ensures no air gaps remain between the cover layer and the core layer and that the interfacial shear strength is not less than 8 N / mm.

[0036] The finished conveyor belt is obtained after cooling, shaping, trimming, and winding. Cooling is achieved using a five-roller cooling system with roller temperatures sequentially set at 60℃, 45℃, 30℃, 20℃, and 15℃, rapidly reducing the belt temperature from 170℃ to room temperature and preventing embrittlement due to increased crystallinity caused by slow cooling. Trimming is performed using a rotating cutter with precision controlled to ±0.5 mm, and the winding tension is maintained at a constant 500N to prevent interlayer misalignment.

[0037] The conveyor belt's overall structure achieved UL94 V-0 rating in vertical combustion tests, with a limiting oxygen index of no less than 38%. After aging in hot air at 200°C for 500 hours, its tensile strength retention rate was no less than 80%, its tear strength was no less than 60 kN / m, and it exhibited no molten droplets and a smoke density rating of less than 300 during combustion. In roller bending fatigue tests, the conveyor belt showed no visible cracks on its surface after 100,000 cycles, and its interlaminar peel strength was no less than 4.5 N / mm.

[0038] Furthermore, the conveyor belt edges are equipped with a heat-sealed edge-wrapping structure. This structure is made of chlorinated polyvinyl chloride (PVC) sheets of the same material, which are wrapped around both sides of the belt body using a high-frequency heat-sealing process to form a continuous sealing layer. The high-frequency heat-sealing frequency is 27.12MHz, the power is 8kW, the heat-sealing time is 3 seconds, the heat-sealing pressure is 0.6MPa, and the edge-wrapping width is 15mm. This structure prevents moisture, dust, or corrosive media from penetrating along the interlayer interface, thereby improving long-term reliability in humid, dusty, or chemically corrosive environments.

[0039] The thickness of the conveyor belt ranges from 4 to 12 mm, with the upper cover layer being 1.5 to 4 mm thick, the lower cover layer being 1 to 3 mm thick, and the tensile core layer being 2 to 6 mm thick. The thickness of each layer is precisely matched and designed according to the tension of the conveying system, the impact load of the material, and the ambient temperature gradient to ensure uniform stress distribution of the overall structure under high-temperature conditions and avoid early failure caused by localized thermal stress concentration.

[0040] In one specific embodiment, a conveyor belt with a thickness of 8 mm is prepared, having an upper cover layer thickness of 3.0 mm, a lower cover layer thickness of 2.0 mm, and a tensile core layer thickness of 3.0 mm. This specification is suitable for cement clinker transfer systems, with a material temperature of approximately 200°C, a belt speed of 1.5 m / s, and a daily operating time of 20 hours.

[0041] As another technical feature of this invention, the chlorinated polyvinyl chloride resin does not undergo a cross-linking reaction during processing. Its molding relies entirely on the thermoplastic melt flow and cooling solidification mechanism. Therefore, it can be manufactured using a continuous extrusion-calendering integrated process, eliminating the need for the intermittent flat vulcanizing equipment required for traditional rubber conveyor belts, significantly shortening the production cycle and reducing energy consumption. Furthermore, since the material system does not contain a vulcanization network, it does not exhibit over-vulcanization or reversion during high-temperature service, and its mechanical property degradation shows a linear and controllable trend.

[0042] To verify the technical effect of the present invention, the following embodiments and comparative examples were set up for comparative testing.

[0043] Example 1: An 8 mm thick conveyor belt sample was prepared according to the above-mentioned preferred formulation and process. Upper cover layer formulation: 100 parts chlorinated polyvinyl chloride resin, 2.4 parts dibutyltin dilaurate, 0.8 parts cerium oxide-lanthanum oxide solid solution, 10 parts melamine polyphosphate, 5 parts zinc borate, 4 parts ammonium molybdate, 4 parts zinc stannate, 9.6 parts trioctyl trimellitate, 2.4 parts epoxidized soybean oil, 0.6 parts calcium stearate, 1.2 parts polyethylene wax, 15 parts silane-treated calcined kaolin, and 5 parts hollow glass microspheres. The lower cover layer formulation was slightly adjusted, with the total plasticizer reduced by 1 part and the inorganic filler reduced by 2 parts. The tensile core layer was made of plasma-treated aramid fabric (treatment time 8 seconds, nitrogen flow rate 10 L / min), with an impregnation slurry solid content of 40% and containing 3% by weight of glycidyl methacrylate-butyl acrylate copolymer.

[0044] Comparative Example 1: A conventional chlorinated polyvinyl chloride conveyor belt formulation was used, with a chlorine content of 63%. Rare earth composite oxides were not used. The heat stabilizer contained only 3.2 parts of dibutyltin dilaurate. The flame retardant system contained only 15 parts of melamine polyphosphate, without zinc borate synergistic effect. The smoke suppressant contained only 8 parts of ammonium molybdate. The plasticizer was all DOP 12 parts. The inorganic filler was untreated kaolin 20 parts. The tensile core layer was untreated aramid fabric, and the impregnation slurry did not contain adhesion promoters.

[0045] Comparative Example 2: A traditional EPDM rubber-based flame-retardant conveyor belt with a thickness of 8 mm was used. The cover layer contained decabromodiphenyl ether flame retardant and antimony trioxide synergist, and the core layer was nylon canvas, which was formed by flat vulcanization.

[0046] All samples were tested for performance according to the same standard, and the results are shown in the table below:

[0047] Test Project Example 1 Comparative Example 1 Comparative Example 2 Limiting oxygen index (%) 39.2 32.5 28.7 UL94 vertical flammability rating V-0 V-1 V-2 Tensile strength retention rate (%) after heat aging at 200℃ for 500 hours 82.3 68.7 52.1 Tear strength (kN / m) 63.5 54.2 48.9 Smoke Density Rating (SDR) 278 385 420 Interlayer peel strength (N / mm) 4.8 3.1 3.9 Surface condition after 100,000 cycles of roller bending fatigue No cracks microcracks Noticeable cracks Interfacial shear strength (N / mm) 8.5 5.2 —

[0048] Test data show that Example 1 is significantly superior to the comparative examples in terms of flame retardancy, thermal stability, mechanical strength retention, and interfacial bonding strength. Especially after long-term thermal aging at 200℃, Example 1 retains over 80% of its tensile strength, while Comparative Examples 1 and 2 retain only 68.7% and 52.1%, respectively. This demonstrates that the multi-level synergistic reinforcement structure and functional additive system constructed in this invention effectively suppresses performance degradation at high temperatures. The smoke density rating is below 300, meeting stringent environmental protection requirements. Data on interlayer peel strength and interfacial shear strength confirm that plasma treatment combined with chemically bonded adhesive promoters significantly improves the interfacial bonding quality between the core layer and the capping layer.

[0049] Furthermore, the sample from Example 1 underwent a simulated operating condition test. It was installed in a simulated cement clinker conveying system with a material temperature of 210±5℃, a belt speed of 1.8 m / s, and continuous operation for 30 days (720 hours). After the operation, testing showed no obvious hardening, cracking, or bulging on the belt surface, a thickness change rate of less than 1.5%, no delamination between layers, and a tensile strength retention rate of 79.6%, which highly matched the laboratory thermal aging data, proving that the conveyor belt of this invention possesses excellent long-term service reliability in a real high-temperature environment.

[0050] The conveyor belt is suitable for industrial scenarios with continuous heat radiation, occasional fires, or strict fire prevention regulations, such as metallurgical sinter cooling and conveying, cement clinker transfer, power plant boiler bottom ash conveying, and chemical high-temperature material transfer. It can operate stably for a long time at an ambient temperature of 180 to 220°C, and can quickly self-extinguish and suppress the spread of fire in the event of a sudden fire, meeting the comprehensive requirements of modern high-reliability material conveying systems for safety, durability, and environmental protection.

[0051] In summary, this invention fundamentally circumvents the inherent constraints of the high-temperature, flame-retardant, and mechanical property triangle in rubber matrices through material system reconstruction and integrated structural-functional design. Chlorinated polyvinyl chloride resin inherently possesses self-extinguishing properties due to its high chlorine content. Combined with a multi-component synergistic flame-retardant system and a thermally insulating filler network, it achieves inherent flame retardancy and low smoke and low toxicity. Precise formulation of heat stabilizers and plasticizers ensures the molecular chain stability and flexibility retention of the material under long-term heat exposure above 200°C. Furthermore, the interfacial chemical bonding design between the aramid-reinforced core layer and the thermoplastic cover layer ensures structural integrity and fatigue resistance under dynamic loads. The overall manufacturing process abandons the energy-intensive vulcanization step, adopting a fully thermoplastic continuous molding route, combining industrial feasibility with consistent performance. Those skilled in the art can adjust the proportions of each component and process parameters according to the technical solution disclosed in this invention, combined with specific application requirements, to achieve large-scale production of high-temperature flame-retardant chlorinated polyvinyl chloride plastic conveyor belts of different specifications and performance levels.

[0052] 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, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-temperature-resistant and flame-retardant chlorinated polyvinyl chloride plastic conveyor belt, comprising an upper cover layer, a lower cover layer, and a tensile body core layer between the two; characterized in that: the upper cover layer and the lower cover layer are both formed by blending and melt-extruding chlorinated polyvinyl chloride resin, heat stabilizer, flame-retardant synergist, smoke suppressant, plasticizer, lubricant, and inorganic filler; the tensile body core layer is formed by hot pressing a surface plasma-treated aramid fiber fabric and a chlorinated polyvinyl chloride resin-based impregnation slurry; the chlorinated polyvinyl chloride resin has a chlorine content of 65 to 72 percent by weight, a Vicat softening point not lower than 110℃, and a tensile strength retention rate after 200℃ hot air aging for 168 hours not lower than 85% of the original value; the heat stabilizer is composed of dibutyltin dilaurate and cerium oxide-lanthanum oxide solid solution at a mass ratio of 3:1, wherein the molar ratio of cerium oxide to lanthanum oxide is 4:1; the flame-retardant synergist is a composite of melamine polyphosphate and zinc borate at a mass ratio of 2:1; the smoke suppressant is a mixture of ammonium molybdate and zinc stannate at a mass ratio of 1:1; the plasticizer is a compounded system of trioctyl trimellitate and epoxy soybean oil at a mass ratio of 4:1; the lubricant is a mixture of calcium stearate and polyethylene wax at a mass ratio of 1:2; the inorganic filler is a composite filler of calcined kaolin treated with γ-aminopropyl triethoxysilane and hollow glass microbeads at a mass ratio of 3:1; the aramid fiber fabric is a para-aramid plain woven fabric with a breaking strength in the warp and weft directions both not lower than 2000N / mm² and an initial modulus not lower than 70GPa; the surface plasma treatment is carried out in a nitrogen atmosphere for 5 to 10 seconds; the impregnation slurry is prepared from chlorinated polyvinyl chloride resin emulsion, glycidyl methacrylate-butyl acrylate copolymer, and deionized water, with a solid content of 40%, wherein the epoxy functional groups of the glycidyl methacrylate-butyl acrylate copolymer form chemical bonds with the amino groups on the surface of the aramid fiber; the thickness of the upper cover layer is 1.5 to 4 millimeters, the thickness of the lower cover layer is 1 to 3 millimeters, the thickness of the tensile body core layer is 2 to 6 millimeters, and the total thickness of the conveyor belt is 4 to 12 millimeters; the conveyor belt is provided with a heat-sealed edge wrapping structure formed by wrapping a continuous sealing layer of chlorinated polyvinyl chloride sheet of the same material on both sides of the belt body through a high-frequency heat sealing process; the conveyor belt has a tensile strength retention rate not lower than 80% after 200℃ hot air aging for 500 hours, an limiting oxygen index not lower than 38%, a vertical burning test reaching UL94 V-0 level, a smoke density level lower than 300, and an interlayer peeling strength not lower than 4.5N / mm. ​ ​ ​ 2. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt according to claim 1, characterized in that: ​ 3. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 4. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 5. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 6. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 7. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 8. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 9. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​ 10. The high temperature resistant, flame-retardant chlorinated polyethylene plastic conveyor belt of claim 1, wherein: ​

Images