An aramid fiber-reinforced solid core conveyor belt and a method of making the same

Abstract

This invention discloses an aramid fiber reinforced solid conveyor belt and its preparation method, relating to the field of conveyor belt technology. Specifically, it includes the following steps: S1: Aramid fiber cloth passes through a continuous plasma surface treatment machine at a uniform speed, and its upper and lower surfaces are subjected to plasma activation treatment to obtain modified aramid fiber cloth; S2: (1) Natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, terpene phenolic resin, modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant, flame retardant, sodium stearate, vulcanizing agent, and vulcanization accelerator are added to a mixing machine and mixed to obtain a compound; (2) The compound is transferred to a calender and calendered to obtain a cover layer; S3: The cover layer, modified aramid fiber cloth, and cover layer are stacked in the order of top to bottom, and then rolled, bonded, and vulcanized to obtain an aramid fiber reinforced solid conveyor belt.

Description

Technical Field

[0001] This invention relates to the field of conveyor belt technology, specifically to an aramid fiber reinforced solid woven conveyor belt and its preparation method. Background Technology

[0002] Solid woven conveyor belts are made by bonding and vulcanizing a high-strength skeleton material as the inner core with a rubber layer. They are widely used in mining, metallurgy, and chemical industries, where high performance requirements exist for flame retardancy, aging resistance, and bonding strength. Conventional solid woven conveyor belts often use aramid fiber cloth as the inner core, but existing aramid-reinforced solid woven conveyor belts have significant drawbacks: First, the surface of aramid fiber cloth is highly inert, resulting in poor compatibility with the rubber cover layer, easily leading to delamination and low bonding strength. Second, the rubber cover layer cannot simultaneously achieve wear resistance, aging resistance, flame retardancy, and bonding strength, resulting in poor overall performance. Third, traditional conveyor belt flame retardancy relies on ordinary flame retardants, which are prone to leaching, leading to poor flame retardant durability of the rubber cover layer. Fourth, conventional fillers have poor dispersibility and weak reinforcing effect, significantly limiting the improvement of the mechanical properties and stability of the rubber cover layer.

[0003] Therefore, the present invention provides a solid woven conveyor belt reinforced with aramid fiber, which greatly solves the defects of existing solid woven conveyor belts reinforced with aramid fiber, and is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide an aramid fiber reinforced solid conveyor belt and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing an aramid fiber reinforced solid woven conveyor belt includes the following steps:

[0007] S1: Aramid fiber cloth passes through a continuous plasma surface treatment machine at a constant speed, and its upper and lower surfaces are subjected to plasma activation treatment to obtain modified aramid fiber cloth.

[0008] S2: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 120-130°C for 2-4 minutes to obtain the first mixture; (2) Add modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant, flame retardant, and sodium stearate to the first mixture and mix at 100-110°C for 4-6 minutes to obtain the second mixture; (3) Add vulcanizing agent and vulcanization accelerator to the second mixture and mix at 80-90°C for 1-2 minutes to obtain the compound; (4) Transfer the compound to a calender and calender it at 95-105°C to form a cover layer of the required size.

[0009] S3: The layers are stacked in the following order from top to bottom: cover layer, modified aramid fiber cloth, and cover layer again. They are then continuously rolled and bonded by a roller bonding molding machine at 85~95℃ and 0.8~1.5MPa. After that, they are transferred to a continuous vulcanizing machine and vulcanized at 150~165℃ and 8~12MPa for 15~30min to obtain a solid aramid fiber reinforced conveyor belt.

[0010] Furthermore, the process parameters for the plasma activation treatment are as follows: the working gas is air, the gas flow rate is 12~16L / min, the frequency is 30±1kHz, the power is 5~10kW, the cloth speed is 2~4m / min, and the treatment distance is 4~8mm.

[0011] Further, the compound comprises the following raw material components in parts by weight: 45-55 parts natural rubber, 20-28 parts styrene-butadiene rubber, 15-25 parts chloroprene rubber, 10-18 parts ethylene propylene diene monomer (EPDM) rubber, 8-12 parts terpene phenolic resin, 4-8 parts modifier, 40-50 parts modified filler, 2-4 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 4-6 parts zinc oxide, 3-5 parts antioxidant, 5-10 parts flame retardant, 1-3 parts sodium stearate, 1-3 parts vulcanizing agent, and 2-4 parts vulcanization accelerator.

[0012] Further, the preparation method of the modifier is as follows: (1) Under nitrogen protection, hexachlorocyclotriphosphazene, anhydrous potassium carbonate, and glycerol-A,A'-diallyl ether are added to xylene and stirred at room temperature for 24-48 h. After rotary evaporation, washing, and drying, an intermediate is obtained; (2) Under nitrogen protection, DOPO and the intermediate are added to xylene and stirred at 120-130℃ for 4-12 h. The temperature is lowered to 50-60℃, and 3-mercapto-1,2,4-triazole and azobisisobutyronitrile are added to the reaction system and stirred for 2-3 h. After rotary evaporation, washing, and drying, the modifier is obtained.

[0013] Furthermore, the intermediate preparation comprises the following raw material components in parts by weight: 3-4 parts hexachlorocyclotriphosphazene, 6-10 parts anhydrous potassium carbonate, 9-12 parts glycerol-A,A'-diallyl ether, and 40-50 parts xylene.

[0014] Further, the preparation of the modifier includes the following raw material components in parts by weight: 9-12 parts of intermediate, 7-9.5 parts of DOPO, 3.3-4.5 parts of 3-mercapto-1,2,4-triazole, 0.3-0.5 parts of azobisisobutyronitrile, and 40-50 parts of xylene.

[0015] Further, the preparation method of the modified filler is as follows: (1) Add vinyltriethoxysilane to an 80~90wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust the pH to 4.5~5.5, stir and mix for 20~40min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse the composite filler in vinyltriethoxysilane hydrolysate, soak for 0.5~1.5h, take it out, wash and dry to obtain the modified filler.

[0016] Furthermore, the volume ratio of the vinyltriethoxysilane and the aqueous ethanol solution is (0.05~0.1):1.

[0017] Furthermore, the ratio of the composite filler and the vinyltriethoxysilane hydrolysate is 1g:(3~6)mL.

[0018] Furthermore, the composite filler is obtained by mixing and compounding silica, carbon black, zinc borate and activated chopped aramid fibers in a mass ratio of (1~2):(3~4):(0.5~1):(1~2).

[0019] Further, the preparation method of the activated chopped aramid fiber is as follows: (1) Immerse the chopped aramid fiber in a sodium hydroxide aqueous solution of 50~100g / L and soak it at 60~70℃ for 20~40min, take it out and wash it to obtain roughened chopped aramid fiber; (2) Immerse the roughened chopped aramid fiber in a hydrochloric acid aqueous solution of 50~100mL / L and soak it at 50~60℃ for 10~30min, take it out, wash it and dry it to obtain activated chopped aramid fiber.

[0020] Furthermore, the ratio of the chopped aramid fiber to the sodium hydroxide aqueous solution is 1g:(3~6)mL.

[0021] Furthermore, the ratio of the coarsened short-cut aramid fiber to the hydrochloric acid aqueous solution is 1g:(3~6)mL.

[0022] Furthermore, the length of the chopped aramid fiber is 3~6mm.

[0023] Furthermore, the antioxidants include, but are not limited to, one or more combinations of antioxidants RD, 4010, 4020, MB, and DQ.

[0024] Furthermore, the flame retardant is a boron-based flame retardant, including one or more combinations of NFR-650, NFR-650S, and NFR-110.

[0025] Furthermore, the vulcanizing agent is sulfur.

[0026] Furthermore, the vulcanization accelerator includes, but is not limited to, one or more combinations of accelerator NS, accelerator DM, accelerator TMTD, and accelerator CZ.

[0027] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0028] (1) Plasma activation treatment of aramid fiber cloth can greatly improve the surface inertness of aramid fibers and form a large number of active sites on the surface of aramid fiber cloth, thereby improving its bonding force with the cover layer and solving the defect of weak interfacial bonding with resin materials. This is the key basis for solving the problem of easy delamination of solid woven conveyor belts in this invention.

[0029] (2) Natural rubber has a low cost and excellent mechanical properties, good wear resistance, and strong adhesion. Using it as the main rubber in the compound of this invention can control costs and ensure the overall strength and structural stability of the conveyor belt, thus providing a basic guarantee for the durability of the conveyor belt. Considering that natural rubber is relatively lacking in heat resistance, aging resistance, and flame retardancy, styrene-butadiene rubber is added to this invention to improve it. Styrene-butadiene rubber has better mechanical properties, wear resistance, heat resistance, and aging resistance than natural rubber, which can compensate for the performance shortcomings of natural rubber to a certain extent. However, styrene-butadiene rubber has poor adhesion, so its proportion should not be too high. At the same time, in order to further improve the flame retardancy of the rubber system, chloroprene rubber is introduced to work synergistically with styrene-butadiene rubber. Chloroprene rubber has excellent heat resistance, adhesion, and flame retardancy. While compensating for the poor adhesion of styrene-butadiene rubber, it can also improve the flame retardancy of natural rubber. Due to limitations in the amount of styrene-butadiene rubber (SBR) incorporated, the rubber system still suffers from issues such as insufficient aging resistance. To further enhance the overall performance of the rubber and improve the durability of the conveyor belt, this invention also incorporates ethylene propylene diene monomer (EPDM). EPDM has excellent aging resistance, which can significantly extend the service life of the conveyor belt. However, unlike SBR and chloroprene rubber, EPDM does not have excellent compatibility with natural rubber. Therefore, this invention incorporates terpene phenolic resin as a compatibilizer, which can effectively promote the compatibility of EPDM with the rubber system. Furthermore, terpene phenolic resin contains a large number of polar hydroxyl groups, which can form hydrogen bonds with the hydroxyl groups on the aramid fiber fabric, thus promoting the overall bonding stability of the conveyor belt.

[0030] (3) In this invention, the hydroxyl group of glycerol-A,A'-diallyl ether and the six P-Cl bonds on hexachlorocyclotriphosphazene undergo a substitution reaction to prepare an intermediate containing multiple unsaturated double bonds. Subsequently, the active hydrogen on DOPO reacts with the unsaturated double bonds on the intermediate to graft a DOPO structure onto the intermediate. Then, the thiol group of 3-mercapto-1,2,4-triazole undergoes a click reaction with the unsaturated double bonds on the intermediate to further graft a triazole structure onto the intermediate, ultimately preparing a modifier with multiple modification functions. Throughout the modification preparation process, it is necessary to reasonably control the amount of DOPO and 3-mercapto-1,2,4-triazole to ensure that the modifier grafts sufficient DOPO and triazole structures while retaining an appropriate amount of unsaturated double bonds. The cyclophosphonitrile, DOPO, and triazole structures in the modifier can form a nitrogen-phosphorus synergistic flame retardant system. Adding this system to the rubber system can impart excellent flame retardant properties to the rubber. In addition, the triazole structure also has excellent anti-aging properties, which can impart excellent aging resistance to the rubber. The residual unsaturated double bonds in the modifier improve the compatibility between the modifier and the rubber system to a certain extent. At the same time, they can form chemical crosslinks with the rubber in the subsequent process, which can not only increase the crosslinking density of the rubber system, but also prevent the migration and precipitation of the modifier, thus achieving efficient and long-term stable modification of the rubber.

[0031] (4) Short-cut aramid fibers also have surface inertness. Therefore, in this invention, the short-cut aramid fibers are subjected to "alkali washing and roughening + acid washing and activation" treatment to introduce active sites on their surface. Then, they are compounded with silica, carbon black, and zinc borate to obtain a composite filler. After modification with vinyltriethoxysilane, the compatibility of the composite filler with the rubber system is significantly improved. Under the action of short-cut aramid fibers, the modified filler can enhance and toughen the rubber. Under the action of silica, carbon black, and zinc borate, it can effectively improve the wear resistance and mechanical properties of the rubber. In addition, zinc borate can also be used as a flame retardant filler to synergistically improve the flame retardant properties of the rubber with the nitrogen-phosphorus synergistic flame retardant system.

[0032] (5) The length of chopped aramid fibers is strictly controlled at 3~6mm. If the length is too long, it will not be easy to disperse; if it is too short, it will be difficult to exert an effective reinforcing effect.

[0033] (6) In this invention, bis-[3-(triethoxysilyl)propyl]tetrasulfide is further introduced into the compound rubber, which contains reactive polysulfide bonds and siloxy groups; wherein, the siloxy groups can form chemical bridges with aramid fiber cloth and rubber, and the polysulfide bonds will break and participate in vulcanization crosslinking. Under the action of bis-[3-(triethoxysilyl)propyl]tetrasulfide, the interfacial bonding force between aramid fiber cloth and rubber layer is greatly promoted.

[0034] (7) In this invention, boron-based flame retardants are also selected as flame retardants. They have the advantages of being non-toxic and low-smoke. They can further synergize with the modifier and zinc borate in the modified filler to further enhance the flame retardant performance of the conveyor belt.

[0035] In summary, this invention, through the rational combination and application of various raw material components in the rubber system, and under the synergistic effect of these components, comprehensively prepares an aramid fiber reinforced solid core conveyor belt with excellent comprehensive properties such as adhesion, flame retardancy, and aging resistance. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0037] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: aramid fiber cloth, model H1000D-AP160, width 600mm, thickness 0.24mm; natural rubber, CAS number 9006-04-6; styrene-butadiene rubber, model SBR1502; chloroprene rubber, model M40; ethylene propylene diene monomer (EPDM) rubber, model EPDM70; terpene phenolic resin, model 803L; hexachlorocyclotriphosphazene, CAS number 940-71-6; glycerol-A,A'-diallyl ether, CAS number 170. 18-07-4; DOPO, CAS No. 35948-25-5; 3-mercapto-1,2,4-triazole, CAS No. 3179-31-5; bis-[3-(triethoxysilyl)propyl]tetrasulfide, CAS No. 40372-72-3; silica, grade 255; carbon black, grade N880; zinc borate, CAS No. 1332-07-6; chopped aramid fibers, lengths of 3mm, 4.5mm, 6mm, 2mm, and 7mm, diameter of 12μm; antioxidant RD; NFR-650; sulfur; accelerator NS; and other raw materials are all commercially available; each part by weight is 100g.

[0038] Preliminary preparations:

[0039] 1. Preparation of activated chopped aramid fibers: (1) Chopped aramid fibers with lengths of 3 mm, 4.5 mm, 6 mm, 2 mm and 7 mm were respectively immersed in 75 g / L sodium hydroxide aqueous solution and soaked at 65 °C for 30 min. They were then removed and washed to obtain roughened chopped aramid fibers; (2) The obtained roughened chopped aramid fibers were then respectively immersed in 75 mL / L hydrochloric acid aqueous solution and soaked at 55 °C for 20 min. They were then removed, washed and dried to obtain activated chopped aramid fibers; wherein, the ratio of chopped aramid fibers to sodium hydroxide aqueous solution was 1 g: 4.5 mL; the ratio of roughened chopped aramid fibers to hydrochloric acid aqueous solution was 1 g: 4.5 mL;

[0040] 2. Preparation of composite filler: (1) Mix silica, carbon black, zinc borate and 3mm activated short-cut aramid fiber in a mass ratio of 1.5:3.5:0.75:1.5 to obtain composite filler A;

[0041] (2) Silica, carbon black, zinc borate and 4.5mm activated short-cut aramid fiber are mixed and compounded in a mass ratio of 1.5:3.5:0.75:1.5 to obtain composite filler B;

[0042] (3) Silica, carbon black, zinc borate and 6mm activated short-cut aramid fiber are mixed and compounded in a mass ratio of 1.5:3.5:0.75:1.5 to obtain composite filler C;

[0043] (4) Silica, carbon black, zinc borate and 2mm activated short-cut aramid fiber are mixed and compounded in a mass ratio of 1.5:3.5:0.75:1.5 to obtain composite filler D;

[0044] (5) Mix silica, carbon black, zinc borate and 7mm activated short-cut aramid fiber in a mass ratio of 1.5:3.5:0.75:1.5 to obtain composite filler E.

[0045] Example 1: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0046] S1: Aramid fiber cloth passes through the PL-BM45 type automated plasma surface treatment machine at a constant speed, and its upper and lower surfaces are subjected to plasma activation treatment to obtain modified aramid fiber cloth.

[0047] The process parameters for plasma activation treatment are as follows: working gas is air, gas flow rate is 14L / min, frequency is 30±1kHz, power is 8kW, cloth speed is 3m / min, and treatment distance is 6mm.

[0048] S2: Preparation of the capping layer:

[0049] S21: Preparation of the modifier: (1) Under nitrogen protection, 3.5 parts of hexachlorocyclotriphosphazene, 8 parts of anhydrous potassium carbonate, and 10.5 parts of glycerol-A,A'-diallyl ether were added to 45 parts of xylene and stirred at room temperature for 36 h. After rotary evaporation, washing, and drying, the intermediate was obtained; (2) Under nitrogen protection, 8.25 parts of DOPO and 10.5 parts of the intermediate were added to 45 parts of xylene and stirred at 125 °C for 8 h. After cooling to 55 °C, 3.9 parts of 3-mercapto-1,2,4-triazole and 0.4 parts of azobisisobutyronitrile were added to the reaction system and stirred for 2.5 h. After rotary evaporation, washing, and drying, the modifier was obtained;

[0050] S22. Preparation of modified filler: (1) Add vinyltriethoxysilane to 85wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust pH to 5, stir and mix for 30 min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse composite filler A in vinyltriethoxysilane hydrolysate, soak for 1 h, take out, wash and dry to obtain modified filler; wherein, the volume ratio of vinyltriethoxysilane to ethanol aqueous solution is 0.075:1; the ratio of composite filler A to vinyltriethoxysilane hydrolysate is 1g:4.5mL;

[0051] S23. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 125°C for 3 min to obtain the first mixture; (2) Add modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant RD, NFR-650, and sodium stearate to the first mixture and mix at 105°C for 5 min to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 min to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0052] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 24 parts styrene-butadiene rubber, 20 parts chloroprene rubber, 14 parts ethylene propylene diene monomer (EPDM) rubber, 10 parts terpene phenolic resin, 6 parts modifier, 45 parts modified filler, 3 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0053] S3: The layers are stacked in the following order from top to bottom: cover layer, modified aramid fiber cloth, and cover layer again. They are then continuously rolled and bonded at 90℃ and 1.2MPa using a roller bonding molding machine. After that, they are transferred to a continuous vulcanizing machine and vulcanized at 158℃ and 10MPa for 20 minutes to obtain a solid aramid fiber reinforced conveyor belt.

[0054] Example 2: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0055] Example 2 is based on Example 1, but with the following adjustment: the amount of raw material components in the compound rubber is adjusted, while other processes remain unchanged. Specifically:

[0056] S23. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 125°C for 3 min to obtain the first mixture; (2) Add modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant RD, NFR-650, and sodium stearate to the first mixture and mix at 105°C for 5 min to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 min to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0057] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 20 parts styrene-butadiene rubber, 15 parts chloroprene rubber, 10 parts ethylene propylene diene monomer (EPDM) rubber, 8 parts terpene phenolic resin, 4 parts modifier, 40 parts modified filler, 2 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0058] Example 3: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0059] Example 3 is based on Example 1, but with the following adjustment: the amount of raw material components in the compound rubber is adjusted, while other processes remain unchanged. Specifically:

[0060] S23. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 125°C for 3 min to obtain the first mixture; (2) Add modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant RD, NFR-650, and sodium stearate to the first mixture and mix at 105°C for 5 min to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 min to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0061] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 28 parts styrene-butadiene rubber, 25 parts chloroprene rubber, 18 parts ethylene propylene diene monomer (EPDM) rubber, 12 parts terpene phenolic resin, 8 parts modifier, 50 parts modified filler, 4 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0062] Example 4: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0063] Example 4 is based on Example 1, with the following adjustments: the length of the chopped aramid fiber is 4.5 mm, i.e., composite filler B is used; other processes remain unchanged. Specifically:

[0064] S22. Preparation of modified filler: (1) Add vinyltriethoxysilane to 85wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust pH to 5, stir and mix for 30min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse composite filler B in vinyltriethoxysilane hydrolysate, soak for 1h, take out, wash and dry to obtain modified filler; wherein, the volume ratio of vinyltriethoxysilane to ethanol aqueous solution is 0.075:1; the ratio of composite filler to vinyltriethoxysilane hydrolysate is 1g:4.5mL.

[0065] Example 5: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0066] Example 5 is based on Example 1, with the following adjustments: the length of the chopped aramid fiber is 6 mm, i.e., composite filler C is used, while other processes remain unchanged. Specifically:

[0067] S22. Preparation of modified filler: (1) Add vinyltriethoxysilane to 85wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust pH to 5, stir and mix for 30 min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse composite filler C in vinyltriethoxysilane hydrolysate, soak for 1 h, take out, wash and dry to obtain modified filler; wherein, the volume ratio of vinyltriethoxysilane to ethanol aqueous solution is 0.075:1; the ratio of composite filler to vinyltriethoxysilane hydrolysate is 1g:4.5mL.

[0068] The following is a control experiment based on Example 1, with comparative examples 1 to 8, as detailed below:

[0069] Comparative Example 1: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0070] Comparative Example 1 is based on Example 1, with the following adjustment: terpene phenolic resin is not added to the compound, while other processes remain unchanged. Specifically:

[0071] S23. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber and ethylene propylene diene monomer rubber into a mixing mill and mix at 125°C for 3 min to obtain the first mixture; (2) Add modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant RD, NFR-650 and sodium stearate to the first mixture and mix at 105°C for 5 min to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 min to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0072] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 24 parts styrene-butadiene rubber, 20 parts chloroprene rubber, 14 parts ethylene propylene diene monomer (EPDM) rubber, 6 parts modifier, 45 parts modified filler, 3 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0073] Comparative Example 2: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0074] Comparative Example 2 is based on Example 1, with the following adjustment: no modifier is added to the compound, while other processes remain unchanged. Specifically:

[0075] S2: Preparation of the capping layer:

[0076] S21. Preparation of modified filler: (1) Add vinyltriethoxysilane to 85wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust pH to 5, stir and mix for 30 min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse composite filler A in vinyltriethoxysilane hydrolysate, soak for 1 h, take out, wash and dry to obtain modified filler; wherein, the volume ratio of vinyltriethoxysilane to ethanol aqueous solution is 0.075:1; the ratio of composite filler A to vinyltriethoxysilane hydrolysate is 1g:4.5mL;

[0077] S22. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 125°C for 3 min to obtain the first mixture; (2) Add modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant RD, NFR-650, and sodium stearate to the first mixture and mix at 105°C for 5 min to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 min to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0078] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 24 parts styrene-butadiene rubber, 20 parts chloroprene rubber, 14 parts ethylene propylene diene monomer (EPDM) rubber, 10 parts terpene phenolic resin, 45 parts modified filler, 3 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0079] Comparative Example 3: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0080] Comparative Example 3 is based on Example 1, with the following adjustment: no modified filler was added, while other processes remained unchanged. Specifically:

[0081] S2: Preparation of the capping layer:

[0082] S21: Preparation of the modifier: (1) Under nitrogen protection, 3.5 parts of hexachlorocyclotriphosphazene, 8 parts of anhydrous potassium carbonate, and 10.5 parts of glycerol-A,A'-diallyl ether were added to 45 parts of xylene and stirred at room temperature for 36 h. After rotary evaporation, washing, and drying, the intermediate was obtained; (2) Under nitrogen protection, 8.25 parts of DOPO and 10.5 parts of the intermediate were added to 45 parts of xylene and stirred at 125 °C for 8 h. After cooling to 55 °C, 3.9 parts of 3-mercapto-1,2,4-triazole and 0.4 parts of azobisisobutyronitrile were added to the reaction system and stirred for 2.5 h. After rotary evaporation, washing, and drying, the modifier was obtained;

[0083] S22. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 125°C for 3 min to obtain the first mixture; (2) Add modifier, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant RD, NFR-650, and sodium stearate to the first mixture and mix at 105°C for 5 min to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 min to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0084] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 24 parts styrene-butadiene rubber, 20 parts chloroprene rubber, 14 parts ethylene propylene diene monomer (EPDM) rubber, 10 parts terpene phenolic resin, 6 parts modifier, 3 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0085] Comparative Example 4: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0086] Comparative Example 4 is based on Example 1, with the following adjustment: bis-[3-(triethoxysilyl)propyl]tetrasulfide is not added to the compound, while other processes remain unchanged. Specifically:

[0087] S23. Mixing and calendering: (1) Add natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, and terpene phenolic resin to a mixing mill and mix at 125°C for 3 minutes to obtain the first mixture; (2) Add modifier, modified filler, zinc oxide, antioxidant RD, NFR-650, and sodium stearate to the first mixture and mix at 105°C for 5 minutes to obtain the second mixture; (3) Add sulfur and accelerator NS to the second mixture and mix at 85°C for 1.5 minutes to obtain the compound; (4) Transfer the compound to a calender and calender at 100°C to form a cover layer with a width of 600 mm and a thickness of 5 mm.

[0088] The compound rubber comprises the following raw material components in parts by weight: 50 parts natural rubber, 24 parts styrene-butadiene rubber, 20 parts chloroprene rubber, 14 parts ethylene propylene diene monomer (EPDM) rubber, 10 parts terpene phenolic resin, 6 parts modifier, 45 parts modified filler, 5 parts zinc oxide, 4 parts antioxidant RD, 7.5 parts NFR-650, 2 parts sodium stearate, 2 parts sulfur, and 3 parts accelerator NS.

[0089] Comparative Example 5: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0090] Comparative Example 5 is based on Example 1, with the following adjustments: the length of the chopped aramid fibers was changed to 2 mm, i.e., composite filler D was used, while other processes remained unchanged. Specifically:

[0091] S22. Preparation of modified filler: (1) Add vinyltriethoxysilane to 85wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust pH to 5, stir and mix for 30min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse composite filler D in vinyltriethoxysilane hydrolysate, soak for 1h, take out, wash and dry to obtain modified filler; wherein, the volume ratio of vinyltriethoxysilane to ethanol aqueous solution is 0.075:1; the ratio of composite filler to vinyltriethoxysilane hydrolysate is 1g:4.5mL.

[0092] Comparative Example 6: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0093] Comparative Example 6 is based on Example 1, with the following adjustments: the length of the chopped aramid fibers is changed to 7 mm, i.e., composite filler E is used, while other processes remain unchanged. Specifically:

[0094] S22. Preparation of modified filler: (1) Add vinyltriethoxysilane to 85wt% ethanol aqueous solution, stir and disperse, then add acetic acid to adjust pH to 5, stir and mix for 30 min to obtain vinyltriethoxysilane hydrolysate; (2) Immerse composite filler E in vinyltriethoxysilane hydrolysate, soak for 1 h, take out, wash and dry to obtain modified filler; wherein, the volume ratio of vinyltriethoxysilane to ethanol aqueous solution is 0.075:1; the ratio of composite filler to vinyltriethoxysilane hydrolysate is 1g:4.5mL.

[0095] Comparative Example 7: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0096] Comparative Example 7 is based on Example 1, with the following adjustment: the aramid fiber cloth is not subjected to plasma activation treatment, while other processes remain unchanged. Specifically:

[0097] S2: The layers are stacked in the following order from top to bottom: cover layer, aramid fiber cloth, and cover layer again. They are then continuously rolled and bonded at 90℃ and 1.2MPa using a roller bonding molding machine. After that, they are transferred to a continuous vulcanizing machine and vulcanized at 158℃ and 10MPa for 20 minutes to obtain an aramid fiber reinforced solid conveyor belt.

[0098] Comparative Example 8: A method for preparing an aramid fiber reinforced solid woven conveyor belt:

[0099] Comparative Example 8 is based on Example 1, with the following adjustments: the double bond reaction was completed during the preparation of the modifier, while other processes remained unchanged. Specifically:

[0100] S21: Preparation of the modifier: (1) Under nitrogen protection, 3.5 parts of hexachlorocyclotriphosphazene, 8 parts of anhydrous potassium carbonate, and 10.5 parts of glycerol-A,A'-diallyl ether were added to 45 parts of xylene and stirred at room temperature for 36 h. After rotary evaporation, washing, and drying, the intermediate was obtained. (2) Under nitrogen protection, 12.375 parts of DOPO and 10.5 parts of the intermediate were added to 45 parts of xylene and stirred at 125 °C for 8 h. The temperature was lowered to 55 °C, and then 5.85 parts of 3-mercapto-1,2,4-triazole and 0.4 parts of azobisisobutyronitrile were added to the reaction system and stirred for 2.5 h. After rotary evaporation, washing, and drying, the modifier was obtained.

[0101] Performance testing: The aramid fiber reinforced solid conveyor belts prepared in Examples 1-5 and Comparative Examples 1-8 were tested for adhesion, flame retardancy, and aging resistance. The specific test methods are as follows:

[0102] (1) Adhesion performance: According to the test method specified in GB / T 6759-2013 "Test method for interlayer adhesion strength of conveyor belt", the aramid fiber reinforced solid conveyor belt was cut into specimens with a length of 200 mm and a width of 25 mm. Under the conditions of 23℃ and 50RH%, the specimens were peeled at a peeling speed of 100 mm / min using a tensile testing machine. The average peel strength of 6 specimens was used to evaluate the adhesion performance.

[0103] (2) Flame retardant performance: According to the test method specified in GB / T 3685-2017 "Test method for combustion characteristics of conveyor belts in laboratory scale", the aramid fiber reinforced solid woven conveyor belt was cut into samples with a length of 200 mm and a width of 25 mm. The flame retardant performance of the aramid fiber reinforced solid woven conveyor belt was tested according to Method A of the alcohol torch burning method. After the alcohol torch was removed, the total flame duration and the maximum single value of the 6 samples were counted to evaluate the flame retardant performance.

[0104] (3) Aging resistance test: According to the test method specified in GB / T3512-2014 "Accelerated aging and heat resistance test method of vulcanized rubber or thermoplastic rubber in hot air", the aramid fiber reinforced solid conveyor belt is cut into a sample size of 200 mm in length and 25 mm in width; it is placed in a forced ventilation aging chamber and aged at 100°C for 168 h with an air flow rate of 1 m / s. Then it is taken out and subjected to an adhesion performance test. The average peel strength of the aged sample is used to evaluate the aging resistance.

[0105] The specific results of the above tests are shown in Table 1 below:

[0106] Table 1

[0107]

[0108] Results Analysis: As can be seen from the data in Table 1 above, this invention, through the rational combination and application of various raw material components in the rubber system, and under the synergistic effect of various raw material components, comprehensively prepares an aramid fiber reinforced solid core conveyor belt with excellent comprehensive properties such as adhesion, flame retardancy, and aging resistance.

[0109] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an aramid fiber reinforced solid woven conveyor belt, characterized in that: Includes the following steps: S1: Aramid fiber cloth passes through a continuous plasma surface treatment machine at a constant speed, and its upper and lower surfaces are subjected to plasma activation treatment to obtain modified aramid fiber cloth. S2: (1) Natural rubber, styrene-butadiene rubber, chloroprene rubber, ethylene propylene diene monomer (EPDM) rubber, terpene phenolic resin, modifier, modified filler, bis-[3-(triethoxysilyl)propyl]tetrasulfide, zinc oxide, antioxidant, flame retardant, sodium stearate, vulcanizing agent, and vulcanization accelerator are added to a mixing mill and mixed to obtain a compound; (2) The compound is transferred to a calender and calendered to obtain a cover layer; S3: The layers are stacked in the following order from top to bottom: cover layer, modified aramid fiber cloth, and cover layer again. After roll pressing and vulcanization, a solid woven conveyor belt reinforced with aramid fiber is obtained. The compound comprises the following raw material components in parts by weight: 45-55 parts natural rubber, 20-28 parts styrene-butadiene rubber, 15-25 parts chloroprene rubber, 10-18 parts ethylene propylene diene monomer (EPDM) rubber, 8-12 parts terpene phenolic resin, 4-8 parts modifier, 40-50 parts modified filler, 2-4 parts bis-[3-(triethoxysilyl)propyl]tetrasulfide, 4-6 parts zinc oxide, 3-5 parts antioxidant, 5-10 parts flame retardant, 1-3 parts sodium stearate, 1-3 parts vulcanizing agent, and 2-4 parts vulcanization accelerator.

2. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 1, characterized in that: The preparation method of the modifier is as follows: (1) Under nitrogen protection, hexachlorocyclotriphosphazene, anhydrous potassium carbonate, and glycerol-A,A'-diallyl ether are added to xylene, stirred and reacted at room temperature, separated and purified to obtain an intermediate; (2) Under nitrogen protection, DOPO and the intermediate are added to xylene, stirred and reacted at 120~130℃; the temperature is lowered to 50~60℃, and 3-mercapto-1,2,4-triazole and azobisisobutyronitrile are added to the reaction system, stirred and reacted, separated and purified to obtain the modifier.

3. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 2, characterized in that: The intermediate preparation comprises the following raw material components in parts by weight: 3-4 parts hexachlorocyclotriphosphazene, 6-10 parts anhydrous potassium carbonate, 9-12 parts glycerol-A,A'-diallyl ether, and 40-50 parts xylene; the modifier preparation comprises the following raw material components in parts by weight: 9-12 parts intermediate, 7-9.5 parts DOPO, 3.3-4.5 parts 3-mercapto-1,2,4-triazole, 0.3-0.5 parts azobisisobutyronitrile, and 40-50 parts xylene.

4. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 1, characterized in that: The modified filler is prepared by: (1) adding vinyltriethoxysilane to an 80-90 wt% ethanol aqueous solution, stirring and dispersing, then adding acetic acid to adjust the pH to 4.5-5.5, stirring and mixing to obtain vinyltriethoxysilane hydrolysate; (2) immersing the composite filler in the vinyltriethoxysilane hydrolysate, soaking treatment, separating and purifying to obtain the modified filler.

5. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 4, characterized in that: The volume ratio of vinyltriethoxysilane to ethanol aqueous solution is (0.05~0.1):1; the ratio of composite filler to vinyltriethoxysilane hydrolysate is 1g:(3~6)mL; the composite filler is obtained by mixing and compounding silica, carbon black, zinc borate and activated short-cut aramid fibers in a mass ratio of (1~2):(3~4):(0.5~1):(1~2).

6. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 5, characterized in that: The preparation method of the activated short-cut aramid fiber is as follows: (1) The short-cut aramid fiber is immersed in a sodium hydroxide aqueous solution of 50~100g / L, soaked at 60~70℃, separated and purified to obtain roughened short-cut aramid fiber; (2) The roughened short-cut aramid fiber is immersed in a hydrochloric acid aqueous solution of 50~100mL / L, soaked at 50~60℃, separated and purified to obtain activated short-cut aramid fiber.

7. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 6, characterized in that: The ratio of the chopped aramid fiber to the sodium hydroxide aqueous solution is 1g:(3~6)mL; the ratio of the coarsened chopped aramid fiber to the hydrochloric acid aqueous solution is 1g:(3~6)mL; and the length of the chopped aramid fiber is 3~6mm.

8. The method for preparing an aramid fiber reinforced solid conveyor belt according to claim 1, characterized in that: The process parameters for the plasma activation treatment are as follows: the working gas is air, the gas flow rate is 12~16L / min, the frequency is 30±1kHz, the power is 5~10kW, the cloth speed is 2~4m / min, and the treatment distance is 4~8mm.

9. A solid woven conveyor belt reinforced with aramid fiber, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 8.

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