Flame-retardant heat-resistant conveyor belt and preparation method thereof

Abstract

The present application belongs to the technical field of conveying belt, and particularly relates to a flame-retardant heat-resistant conveying belt and a preparation method thereof. The flame-retardant heat-resistant conveying belt provided by the present application comprises a framework layer and a covering rubber layer, and the covering rubber layer comprises the following components: ethylene-propylene-diene rubber, nitrile rubber, flame-retardant resin, reinforcing agent, nano flame-retardant agent, accelerator, antioxidant and sulfur. In the present application, the flame-retardant resin is used as part of the flame-retardant agent instead of the traditional flame-retardant agent to be added into the covering rubber, so as to reduce the influence of the amount of the flame-retardant agent on the mechanical properties of the covering rubber; the bisphenol A-bis(diphenyl phosphate) modified nano aluminum hydroxide is used as the nano flame-retardant agent to be added into the covering rubber, so as to improve the compatibility of the nano aluminum hydroxide with the covering rubber and the flame-retardant heat-resistant properties of the covering rubber; and the 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide are used to form the accelerator together, so as to improve the vulcanization efficiency and improve the mechanical properties and aging resistance of the covering rubber.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of conveying belts, and particularly relates to a flame-retardant heat-resistant conveying belt and a preparation method thereof. BACKGROUND

[0002] In the production and transportation link of the coal industry, the conveying belt is the core equipment connecting various production nodes and undertakes the key task of coal from mining, washing and transportation. Due to the special nature of the coal production environment, such as flammability, high temperature and dustiness, ordinary conveying belts cannot meet the safety and durability requirements, and the flame-retardant heat-resistant conveying belt emerges as the times require and becomes an important equipment to ensure the safety production of the coal industry.

[0003] At present, most of the heat-resistant conveying belts on the market do not have flame-retardant properties, and the materials being conveyed in a high-temperature state or even with an open flame will cause safety hazards. In order to improve the flame-retardant properties of the conveying belt, a small number of conveying belts add a large amount of flame retardants in the raw materials, but the addition of a large amount of flame retardants will cause the performance of the covering rubber of the conveying belt to decrease, the elongation to decrease, and the wear to be large, especially the wear resistance of the covering rubber of the conveying belt to decrease significantly, which will cause the service life of the conveying belt to be shortened. Therefore, it is necessary to develop a new type of flame-retardant heat-resistant conveying belt to solve the technical problems existing in the existing conveying belts.

[0004] The Chinese patent application file with the publication number CN117165009A discloses a flame-retardant antistatic conveying belt covering rubber, which comprises polyvinyl chloride resin, powder nitrile rubber, chlorinated polyethylene, organic tin stabilizer, stearic acid, carbon black, liquid antistatic agent, dioctyl phthalate, organic flame retardant and inorganic flame retardant. The phosphorus-nitrogen flame retardant formed by adding bis-dinitranaphthone phenyl phosphate in the formula has high heat resistance, and can play a role in flame retardation and antistatic performance when added to polyvinyl chloride resin and powder nitrile rubber, thereby improving the service life of the conveying belt covering rubber. However, the amount of the organic flame retardant and the inorganic flame retardant in the formula is high, and there is no compatibility design with the matrix resin. The inorganic flame retardant is a rigid particle, and when the amount is too high, it is not uniformly dispersed, and the interfacial bonding force with the matrix is poor, stress concentration points are easily formed, and thus the tensile strength and the tear strength are significantly reduced. At the same time, the high amount of inorganic flame retardant also causes the hardness of the rubber compound to increase, the elasticity to decrease, the wear rate of the covering rubber to increase, and the service life of the conveying belt to be shortened. SUMMARY

[0005] In order to solve the problem of the decrease in the tensile properties and the wear resistance of the conveying belt caused by the large amount of flame retardant in the prior art, the present application provides a flame-retardant heat-resistant conveying belt and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A fire-retardant heat-resistant conveying belt comprises a skeleton layer and a cover rubber layer, the cover rubber layer comprises the following components and their weight fractions:

[0008] EPDM 50-70 parts, nitrile rubber 40-50 parts, fire-retardant resin 30-40 parts, reinforcing agent 10-15 parts, nano fire-retardant agent 10-20 parts, accelerator 3-8 parts, antioxidant 5-10 parts, sulfur 5-10 parts;

[0009] The preparation method of the fire-retardant resin is as follows: phenyltriethoxysilane, p-methylphenyltriethoxysilane and ethanol are added into a reaction kettle, phenyldichlorophosphate is added, stirred uniformly, heated to 70-80 DEG C for 1.5-2 h, continuously heated to 95-100 DEG C for 1.6-2.2 h, continuously heated to 105-110 DEG C, reacted for 0.5-1 h, then reduced pressure distillation is carried out, and cooled to obtain the fire-retardant resin.

[0010] By the above technical scheme, the phosphate groups are introduced into the silicon resin structure to form a silicon-phosphorus synergistic fire-retardant system, which is added to the cover rubber to effectively improve the fire-retardant performance of the cover rubber, wherein the silicon element is converted into silicon dioxide or silicon-oxygen cokes during combustion to form an inorganic protective layer on the surface of the conveying belt, which insulates oxygen and heat transmission, prevents flame spreading and further degradation of the base material, and the phosphate groups decompose to produce acidic substances such as phosphoric acid and polyphosphoric acid during combustion, which catalyzes the dehydration and carbonization of the resin to promote the formation of carbon layer, and the released phosphorus radicals can capture active radicals in the combustion chain reaction to prevent gas phase combustion.

[0011] Further, the molar ratio of the phenyltriethoxysilane, p-methylphenyltriethoxysilane and phenyldichlorophosphate in the preparation method of the fire-retardant resin is 3-5:1:2-3.

[0012] Further, the temperature of the reduced pressure distillation in the preparation method of the fire-retardant resin is carried out in stages, and the temperatures are 100-105 DEG C, 110-115 DEG C, 120-130 DEG C, 140-145 DEG C and 150-155 DEG C, respectively, and the time of the reduced pressure distillation is 30-40 min, 25-30 min, 25-30 min, 25-30 min and 80-90 min, respectively.

[0013] In the above technical solution, the solvent in the flame-retardant resin system is removed by adopting the way of staged vacuum distillation, which can effectively control the viscosity rise of the flame-retardant resin, prevent local overheating, give the resin system time to relax, and avoid resin overheating or gelation. At the same time, the staged vacuum distillation can effectively reduce the loss rate of phosphorus in the flame-retardant resin and improve the flame-retardant performance of the flame-retardant resin.

[0014] Further, the preparation method of the nano flame retardant is as follows: adding nano aluminum hydroxide into acetone, ultrasonic dispersion, heating to 65-70℃, adding bisphenol A-bis(diphenyl phosphate) dropwise, stirring for 3-4h, cooling, vacuum distillation, drying, grinding, and obtaining the nano flame retardant.

[0015] In the above technical solution, the phosphorus-oxygen double bond in bisphenol A-bis(diphenyl phosphate) forms a coordination bond with aluminum ions, so that bisphenol A-bis(diphenyl phosphate) is connected with nano aluminum oxide to form a stable covalent bond, forming a double flame-retardant system of inorganic flame-retardant + organic flame-retardant. Nano aluminum oxide undergoes dehydration reaction at high temperature, releases crystal water, absorbs a large amount of heat, reduces the surface temperature of the material, and the released crystal water becomes steam after being released, which dilutes the oxygen concentration in the combustion area and inhibits the combustion reaction. After dehydration, the nano aluminum oxide particles accumulate on the surface of the material to form a dense inorganic protective layer to block the transfer of heat and oxygen; bisphenol A-bis(diphenyl phosphate) will decompose to produce phosphoric acid substances when burning, which catalyzes the polymer to form carbon, and at the same time releases phosphorus-based free radicals to inhibit the gas phase combustion reaction. Therefore, the nano flame retardant can have a synergistic effect of physical cooling + chemical inhibition + catalytic carbonization, which can significantly improve the flame-retardant effect of the material.

[0016] Further, the molar ratio of the nano aluminum hydroxide to bisphenol A-bis(diphenyl phosphate) in the preparation method of the nano flame retardant is 3-5:1-2.

[0017] Further, the power of the ultrasonic dispersion in the preparation method of the nano flame retardant is 30-40kHz, the duty cycle is 30%-40%, and the ultrasonic dispersion time is 2-4h.

[0018] Further, the temperature of the vacuum distillation in the preparation method of the nano flame retardant is 60-70℃, and the vacuum distillation time is 40-50min.

[0019] Further, the reinforcing agent is one or more of carbon black, white carbon black, calcium carbonate, kaolin, and talc.

[0020] Through the above technical solution, the addition of the reinforcing agent in the conveyor belt cover rubber can significantly improve the tensile strength of the cover rubber, enhance the tear resistance, resist crack propagation, improve the wear resistance of the conveyor belt, and prolong the service life.

[0021] Further, the accelerator is composed of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide in a mass ratio of 8-12:5-7.

[0022] In the above scheme, the use of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide together to form the accelerator can effectively reduce the vulcanization temperature of the cover rubber, shorten the vulcanization time, improve the vulcanization efficiency, and improve the mechanical properties and aging resistance of the cover rubber. Among them, 2-mercaptobenzothiazole as a vulcanization activation center can promote the decomposition efficiency of N-cyclohexyl-2-benzothiazole sulfenamide, increase the number of effective crosslinking points, and refine the crosslinking network to avoid local stress concentration. N-cyclohexyl-2-benzothiazole sulfenamide generates active sulfur by decomposition during vulcanization, and forms stable polysulfide crosslinking with rubber molecules, giving the vulcanized rubber high tensile strength and elasticity.

[0023] Further, the antioxidant is one or more of antioxidant 4020, antioxidant 4010NA, microcrystalline wax, antioxidant 168, and antioxidant 1010.

[0024] Further, the skeleton layer is aramid canvas.

[0025] The application also provides a preparation method of the flame-retardant heat-resistant conveyor belt, specifically comprising the following steps:

[0026] S1: Put the ethylene-propylene-diene rubber, nitrile rubber, and flame-retardant resin into a banbury mixer for blending, and then add the reinforcing agent, nano flame retardant, accelerator, antioxidant, and sulfur for mixing, to obtain cover rubber;

[0027] S2: Dip the skeleton layer material in liquid phenolic resin, heat to 60-80 DEG C, and keep for 5-10 min, and then continue to heat to 140-160 DEG C, and keep for 10-15 min, to obtain an impregnated skeleton;

[0028] S3: Compound the cover rubber obtained in step S1 with the impregnated skeleton obtained in step S2, and then perform vulcanization treatment to obtain the flame-retardant heat-resistant conveyor belt.

[0029] Through the above technical scheme, the skeleton layer impregnated with liquid phenolic resin is compounded with the cover rubber, which effectively improves the bonding performance between the cover rubber and the skeleton layer, and effectively prolongs the service life of the conveyor belt.

[0030] Further, the blending temperature in step S1 is 140-160 DEG C, and the blending time is 30-50 min; the mixing temperature is 140-160 DEG C, and the mixing time is 20-40 min; the dipping temperature in step S2 is 40-50 DEG C, and the dipping time is 0.5-1 min; the vulcanization treatment temperature in step S3 is 150-170 DEG C.

[0031] The fire-retardant heat-resistant conveying belt and the preparation method thereof have the following technical advantages:

[0032] (1) The fire-retardant resin is used as part of the fire retardant instead of the traditional fire retardant to be added into the covering rubber, so as to effectively reduce the influence of the amount of the fire retardant on the mechanical properties of the covering rubber and improve the fire-retardant properties of the covering rubber.

[0033] (2) The bisphenol A-bis(diphenyl phosphate) modified nano-aluminum hydroxide is used as the nano fire retardant to be added into the covering rubber, so as to not only improve the compatibility of the nano-aluminum hydroxide with the covering rubber, but also effectively improve the fire-retardant and heat-resistant properties of the covering rubber.

[0034] (3) The 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide are used as the accelerators to effectively reduce the vulcanization temperature of the covering rubber, shorten the vulcanization time, improve the vulcanization efficiency, and improve the mechanical properties and aging resistance of the covering rubber. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The infrared spectrum of the fire-retardant resin prepared in Preparation Example 3 is shown. DETAILED DESCRIPTION

[0036] The present application will be further described in conjunction with specific examples. However, the present application is not limited to the following examples. Those skilled in the art can make various modifications according to the basic idea of the present application, as long as the modifications do not deviate from the basic idea of the present application, and the modifications are within the scope of the present application.

[0037] The raw materials in the present embodiment are all commercially available products.

[0038] Preparation Example 1

[0039] The preparation method of the fire-retardant resin is as follows: 3 mol of phenyltriethoxysilane, 1 mol of p-methylphenyltriethoxysilane and 150 mL of ethanol are added into a reaction kettle, 2 mol of phenyldichlorophosphate is added, stirred uniformly, heated to 70°C for 1.5 h, continuously heated to 95°C for 1.6 h, continuously heated to 105°C for 0.5 h, and then subjected to stage-wise vacuum distillation (100°C vacuum distillation for 30 min, 110°C vacuum distillation for 25 min, 120°C vacuum distillation for 25 min, 140°C vacuum distillation for 25 min, and 150°C vacuum distillation for 80 min), and cooled to obtain the fire-retardant resin.

[0040] Preparation Example 2

[0041] The preparation method of the flame-retardant resin is as follows: 5 mol of phenyl triethoxysilane, 1 mol of p-methyl phenyl triethoxysilane and 150 mL of ethanol are added into a reaction kettle, 3 mol of phenyl dichlorophosphate is added, stirred uniformly, heated to 80°C for 2 h, continuously heated to 100°C for 2.2 h, continuously heated to 110°C for 1 h, and then subjected to stage-by-stage reduced pressure distillation (105°C reduced pressure distillation for 40 min, 115°C reduced pressure distillation for 30 min, 130°C reduced pressure distillation for 30 min, 145°C reduced pressure distillation for 30 min, and 155°C reduced pressure distillation for 90 min), and cooled to obtain the flame-retardant resin.

[0042] Preparation Example 3

[0043] The preparation method of the flame-retardant resin is as follows: 5 mol of phenyl triethoxysilane, 1 mol of p-methyl phenyl triethoxysilane and 150 mL of ethanol are added into a reaction kettle, 3 mol of phenyl dichlorophosphate is added, stirred uniformly, heated to 80°C for 2 h, continuously heated to 100°C for 2.2 h, continuously heated to 110°C for 1 h, and then subjected to stage-by-stage reduced pressure distillation (105°C reduced pressure distillation for 40 min, 115°C reduced pressure distillation for 30 min, 130°C reduced pressure distillation for 30 min, 145°C reduced pressure distillation for 30 min, and 155°C reduced pressure distillation for 90 min), and cooled to obtain the flame-retardant resin.

[0044] Preparation Example 4

[0045] The preparation method of the nano flame retardant is as follows: 3 mol of nano aluminum hydroxide is added into 50 mL of acetone, ultrasonic dispersed for 2 h under 30 kHz (duty cycle is 30%), heated to 65°C, 1 mol of bisphenol A-bis(diphenyl phosphate) is added dropwise, stirred for 3 h, cooled, subjected to reduced pressure distillation for 40 min under 60°C, dried, and ground to obtain the nano flame retardant.

[0046] Preparation Example 5

[0047] The preparation method of the nano flame retardant is as follows: 5 mol of nano aluminum hydroxide is added into 50 mL of acetone, ultrasonic dispersed for 4 h under 40 kHz (duty cycle is 40%), heated to 70°C, 2 mol of bisphenol A-bis(diphenyl phosphate) is added dropwise, stirred for 4 h, cooled, subjected to reduced pressure distillation for 50 min under 70°C, dried, and ground to obtain the nano flame retardant.

[0048] Preparation Example 6

[0049] The preparation method of the nano flame retardant is as follows: 4.2 mol of nano aluminum hydroxide is added into 50 mL of acetone, ultrasonic dispersion is carried out for 3.2 h under 35 kHz (the duty cycle is 35%), heating to 68℃, dropwise addition of 1.6 mol of bisphenol A-bis(diphenyl phosphate), stirring reaction for 3.5 h, cooling, distillation under reduced pressure for 45 min at 65℃, drying, grinding, to obtain the nano flame retardant.

[0050] Example 1

[0051] A flame-retardant heat-resistant conveyor belt, comprising an aramid canvas skeleton layer and a cover rubber layer, the cover rubber layer comprising the following components and their weight fractions: ethylene-propylene-diene rubber 50 parts, nitrile rubber 50 parts, flame-retardant resin 30 parts, reinforcing agent 10 parts, nano flame retardant 20 parts, accelerator 3 parts, antioxidant 4020 5 parts, sulfur 5 parts. The reinforcing agent is composed of carbon black and white carbon black in a mass ratio of 1:1; the accelerator is composed of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide in a mass ratio of 8:5. The flame-retardant resin is prepared by Preparation Example 1, and the nano flame retardant is prepared by Preparation Example 4.

[0052] The preparation method of the flame-retardant heat-resistant conveyor belt is as follows:

[0053] S1: Put the ethylene-propylene-diene rubber, nitrile rubber and flame-retardant resin into a banbury mixer and blend at 140℃ for 50 min, then add the reinforcing agent, nano flame retardant, accelerator, antioxidant and sulfur and mix at 140℃ for 40 min to obtain the cover rubber;

[0054] S2: Dip the skeleton layer material in liquid phenolic resin at 40℃ for 0.5 min, then heat to 60℃, keep for 5 min, continue to heat to 140℃, keep for 10 min to obtain the dipped skeleton;

[0055] S3: Compound the cover rubber obtained in step S1 with the dipped skeleton obtained in step S2, then perform vulcanization treatment at 150℃ to obtain the flame-retardant heat-resistant conveyor belt.

[0056] Example 2

[0057] A flame-retardant heat-resistant conveyor belt, comprising an aramid canvas skeleton layer and a cover rubber layer, the cover rubber layer comprising the following components and their weight fractions: ethylene-propylene-diene rubber 70 parts, nitrile rubber 40 parts, flame-retardant resin 40 parts, reinforcing agent 15 parts, nano flame retardant 10 parts, accelerator 8 parts, antioxidant 4010NA 10 parts, sulfur 10 parts. The reinforcing agent is composed of carbon black and calcium carbonate in a mass ratio of 1:1; the accelerator is composed of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide in a mass ratio of 12:7. The flame-retardant resin is prepared by Preparation Example 2, and the nano flame retardant is prepared by Preparation Example 5.

[0058] The preparation method of the flame-retardant heat-resistant conveying belt is as follows:

[0059] S1: Put the ethylene-propylene-diene rubber, nitrile rubber and flame-retardant resin into a mixer and blend at 160℃ for 30min, then add the reinforcing agent, nano flame-retardant agent, accelerator, antioxidant and sulfur and mix at 160℃ for 20min to obtain a covering rubber;

[0060] S2: Dip the skeleton layer material in liquid phenolic resin at 50℃ for 1min, then heat to 80℃ and keep for 10min, and continue to heat to 160℃ and keep for 15min to obtain an impregnated skeleton;

[0061] S3: Compound the covering rubber obtained in step S1 with the impregnated skeleton obtained in step S2, and then perform vulcanization treatment at 170℃ to obtain the flame-retardant heat-resistant conveying belt.

[0062] Example 3

[0063] A flame-retardant heat-resistant conveying belt comprises an aramid canvas skeleton layer and a covering rubber layer, wherein the covering rubber layer comprises the following components and their weight fractions: ethylene-propylene-diene rubber 62 parts, nitrile rubber 44 parts, flame-retardant resin 37 parts, reinforcing agent 13 parts, nano flame-retardant agent 18 parts, accelerator 6 parts, antioxidant 168 parts, and sulfur 8 parts. The reinforcing agent is composed of white carbon black and kaolin in a ratio of 1:1; the accelerator is composed of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide in a mass ratio of 11:6. The flame-retardant resin is prepared according to Preparation Example 3, and the nano flame-retardant agent is prepared according to Preparation Example 6.

[0064] The preparation method of the flame-retardant heat-resistant conveying belt is as follows:

[0065] S1: Put the ethylene-propylene-diene rubber, nitrile rubber and flame-retardant resin into a mixer and blend at 150℃ for 40min, then add the reinforcing agent, nano flame-retardant agent, accelerator, antioxidant and sulfur and mix at 150℃ for 30min to obtain a covering rubber;

[0066] S2: Dip the skeleton layer material in liquid phenolic resin at 45℃ for 0.8min, then heat to 70℃ and keep for 8min, and continue to heat to 150℃ and keep for 12min to obtain an impregnated skeleton;

[0067] S3: Compound the covering rubber obtained in step S1 with the impregnated skeleton obtained in step S2, and then perform vulcanization treatment at 160℃ to obtain the flame-retardant heat-resistant conveying belt.

[0068] Comparative Example 1

[0069] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of nano flame retardant is used to replace the flame-retardant resin in the present comparative example.

[0070] Comparative Example 2

[0071] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of flame-retardant resin is used to replace the nano flame retardant in the present comparative example.

[0072] Comparative Example 3

[0073] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of phenyl triethoxysilane is used to replace phenyl dichlorophosphate in the flame-retardant resin of the present comparative example.

[0074] Comparative Example 4

[0075] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that the molar ratio of phenyl triethoxysilane, p-methyl phenyl triethoxysilane and phenyl dichlorophosphate in the preparation method of the flame-retardant resin in the present comparative example is 1:5:7.

[0076] Comparative Example 5

[0077] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of vinyl trimethoxysilane is used to replace bisphenol A-bis(diphenyl phosphate) in the preparation method of the nano flame retardant in the present comparative example.

[0078] Comparative Example 6

[0079] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of nano aluminum hydroxide is used to replace the nano flame retardant in the present comparative example.

[0080] Comparative Example 7

[0081] The flame-retardant heat-resistant conveyor belt and the preparation method thereof in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that the accelerator in the present comparative example is 2-mercaptobenzothiazole.

[0082] Test Example

[0083] Heat resistance: The conveyor belts prepared in Example 1-Example 3 and Comparative Example 1-Comparative Example 7 were tested for heat resistance according to GB / T 33510-2017.

[0084] Oxygen index test: HC-2 type oxygen index instrument produced by Nanjing Jiangning Analysis Instrument Factory was used to test the conveyor belts prepared from Example 1 to Example 3 and Comparative Example 1 to Comparative Example 7. Each group of conveyor belts was cut into 15 samples of (80.0 x 6.5) mm, and the average value of the oxygen index of the 15 samples of each group was recorded.

[0085] Vertical combustion test: The conveyor belts prepared from Example 1 to Example 3 and Comparative Example 1 to Comparative Example 7 were tested according to GB / T 10707-2008. The conveyor belts were cut into 5 samples of (130.0 x 13) mm, vertically placed, and the combustion phenomenon was recorded after applying flame twice from the bottom, and then the samples were graded.

[0086] Mechanical property test: The UTM4203 type universal electronic testing machine produced by Shenzhen Sansi Longxian Technology Co., Ltd. was used to test the mechanical properties of the conveyor belts prepared from Example 1 to Example 3 and Comparative Example 1 to Comparative Example 7. The tensile strength and elongation at break were tested according to GB / T 528-2009, and the sample was cut into dumbbell-shaped sample, and the displacement control was 500 mm / min; the tear strength test was carried out according to GB / T 529-2008 standard, and the sample was cut into right-angle shape, and the displacement control was 500 mm / min.

[0087] The test results are shown in Table 1 and Table 2.

[0088] Table 1: Results of flame-retardant heat-resistant performance test

[0089]

[0090] Table 2: Results of mechanical property test

[0091]

[0092] As shown in Table 1, the burning depth of the flame-retardant heat-resistant conveyor belt provided by the present application is less than 0.15 mm, the limiting oxygen index is 37.9%-39.5%, and the vertical combustion grade is V-0 grade, which fully shows that the flame-retardant heat-resistant conveyor belt provided by the present application has good flame-retardant heat-resistant performance; as shown in Table 2, the tensile strength of the flame-retardant heat-resistant conveyor belt provided by the present application is 8.84-9.10 MPa, the elongation at break is 937%-956%, and the tear strength is 17.11-18.32 N / mm, which shows that the flame-retardant heat-resistant conveyor belt provided by the present application has good mechanical properties.

[0093] Compared with Example 3, the comparative example 1 uses equal amount of nano flame retardant instead of the flame retardant resin, but the flame retardant performance of the prepared conveyor belt is reduced, and the mechanical property is increased, the comparative example 2 uses equal amount of flame retardant resin instead of nano flame retardant, but the flame retardant performance and the mechanical property of the prepared conveyor belt are reduced in different degrees, which shows that the flame retardant resin and the nano flame retardant in the application play a synergistic effect, the nano flame retardant can improve the flame retardant performance of the conveyor belt while improving the mechanical property of the conveyor belt; the comparative example 3 uses equal amount of phenyl triethoxysilane instead of phenyl dichlorophosphate, and the flame retardant performance of the prepared conveyor belt is poor, which is caused by not introducing phosphate groups in the flame retardant resin; the comparative example 4 changes the molar ratio of phenyl triethoxysilane, p-methyl phenyl triethoxysilane and phenyl dichlorophosphate, but the flame retardant performance of the prepared conveyor belt is poor, which shows that the molar ratio of phenyl triethoxysilane, p-methyl phenyl triethoxysilane and phenyl dichlorophosphate in the preparation process of the flame retardant resin has been optimized; the comparative example 5 uses equal amount of vinyl trimethoxysilane instead of bisphenol A-bis (diphenyl phosphate), but the flame retardant performance of the prepared conveyor belt is poor, the comparative example 6 uses equal amount of nano aluminum hydroxide instead of nano flame retardant, but the flame retardant performance and the mechanical property of the prepared conveyor belt are poor, which shows that the introduction of phosphate groups on the surface of nano aluminum hydroxide in the application can effectively improve the flame retardant performance of the conveyor belt, and the modification of nano aluminum hydroxide can improve the compatibility with the covering rubber; the comparative example 7 changes the type of accelerator, but the mechanical property of the prepared conveyor belt is poor, which shows that the use of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazole sulfenamide to form an accelerator can effectively improve the mechanical property of the conveyor belt.

[0094] In addition, the flame retardant resin prepared in the preparation example 3 is also subjected to infrared spectrum test, and the test result is shown in Figure 1 . It can be known from Figure 1 that the stretching vibration peak of Si-O-Si appears at 1025m -1 , the absorption peak of Si-phenyl appears at 1127cm -1 , the absorption peak of phenyl appears at 3082cm -1 , 1589cm -1 , 1430cm -1 , the absorption peak of benzyl appears at 2953cm -1 , the absorption peak of -P=O appears at 1318cm -1 , and the absorption peak of C-O-P appears at 1062cm -1 , which shows that the phosphate groups are successfully introduced into the silicon resin structure in the application.

[0095] The above embodiments are merely illustrative of the present application and are not intended to limit the present application. Those skilled in the art can modify the above embodiments without departing from the spirit and scope of the present application. All equivalent modifications or changes made by those skilled in the art without departing from the technical ideas of the present application shall fall within the scope of the present application.

Claims

1. A fire-retardant heat-resistant conveyor belt, characterized by, The covering rubber layer comprises the following components and their weight fractions: Ethylene propylene terpolymer 50-70 parts, nitrile rubber 40-50 parts, flame-retardant resin 30-40 parts, reinforcing agent 10-15 parts, nano flame retardant 10-20 parts, accelerator 3-8 parts, antioxidant 5-10 parts, sulfur 5-10 parts; The preparation method of the flame-retardant resin is as follows: phenyltriethoxysilane, p-methylphenyltriethoxysilane and ethanol are added into a reaction kettle, phenyldichlorophosphate is added, stirred uniformly, heated to 70-80℃ for 1.5-2h, continuously heated to 95-100℃ for 1.6-2.2h, continuously heated to 105-110℃ for 0.5-1h, and then reduced pressure distillation is carried out, cooled to obtain the flame-retardant resin; wherein the molar ratio of phenyltriethoxysilane, p-methylphenyltriethoxysilane and phenyldichlorophosphate is 3-5:1:2-3; The preparation method of the nano flame retardant is as follows: nano aluminum hydroxide is added into acetone, ultrasonic dispersion is carried out, heated to 65-70℃, bisphenol A-bis(diphenyl phosphate) is added dropwise, stirred for 3-4h, cooled, reduced pressure distillation is carried out, dried, ground to obtain the nano flame retardant; wherein the molar ratio of nano aluminum hydroxide and bisphenol A-bis(diphenyl phosphate) is 3-5:1-2; The accelerator is composed of 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfenamide according to a mass ratio of 8-12:5-7.

2. The fire-retardant heat-resistant conveyor belt according to claim 1, characterized in that, In the preparation method of the flame-retardant resin, the temperature of the reduced pressure distillation is carried out in stages, in order of 100-105℃, 110-115℃, 120-130℃, 140-145℃, 150-155℃, and the time of the reduced pressure distillation is in order of 30-40min, 25-30min, 25-30min, 25-30min, 80-90min.

3. The fire-retardant heat-resistant conveyor belt according to claim 1, characterized in that, In the preparation method of the nano flame retardant, the power of the ultrasonic dispersion is 30-40kHz, the duty cycle is 30%-40%, and the time of the ultrasonic dispersion is 2-4h; the temperature of the reduced pressure distillation is 60-70℃, and the time of the reduced pressure distillation is 40-50min.

4. The fire-retardant heat-resistant conveyor belt according to claim 1, characterized in that, The reinforcing agent is one or several of carbon black, white carbon black, calcium carbonate, kaolin and talcum powder; the antioxidant is one or several of antioxidant 4020, antioxidant 4010NA, microcrystalline wax, antioxidant 168 and antioxidant 1010; and the skeleton layer is aramid canvas.

5. The method of producing a flame-retardant heat-resistant conveyor belt according to any one of claims 1 to 4, characterized in that, Specifically, S1: ethylene propylene terpolymer, nitrile rubber and flame-retardant resin are put into a banbury mixer for blending, and then reinforcing agent, nano flame retardant, accelerator, antioxidant and sulfur are mixed to obtain a covering rubber layer; S2: the skeleton layer material is impregnated in liquid phenolic resin, then heated to 60-80℃, and kept for 5-10min, and then heated to 140-160℃, and kept for 10-15min, to obtain an impregnated skeleton; S3: the covering glue prepared in step S1 is compounded with the impregnated skeleton prepared in step S2, and then vulcanization treatment is performed, to obtain a flame-retardant heat-resistant conveying belt.

6. The method of claim 5, wherein the flame-retardant heat-resistant conveyor belt is prepared by the steps of: The temperature for blending in step S1 is 140-160℃, and the blending time is 30-50min; the temperature for mixing is 140-160℃, and the mixing time is 20-40min; the temperature for impregnation in step S2 is 40-50℃, and the impregnation time is 0.5-1min; the temperature for vulcanization treatment in step S3 is 150-170℃.

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