Burning-resistant conveyor belt cover rubber, preparation method thereof and burning-resistant test device

Abstract

The invention relates to a burning-resistant conveyor belt cover rubber, a preparation method thereof and a burning-resistant test device. The cover rubber comprises the following components: hydrogenated nitrile rubber, chloroprene rubber, a composite burning-resistant agent, carbon black N330, magnesium oxide, zinc oxide, dicumyl peroxide, dioctyl phthalate, ammonium polyphosphate and an anti-aging agent MB. The preparation method comprises the following steps: preparing the composite burning-resistant agent, plastifying and premixing raw rubber, carrying out first-stage mixing, cooling, carrying out second-stage mixing and carrying out open milling. The prepared covering rubber can be used for the burning-resistant conveying belt, the problem that traditional heat-resistant covering rubber is not resistant to material ablation is solved, the performance of the covering rubber reaches the physical property and burning-resistant performance standard of a covering layer in HG / T 4732 burning-resistant conveying belt, and the testing stability and reliability of a testing method adopting the performance testing device are better.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of conveying belt, and discloses a burn-resistant conveying belt cover rubber, a preparation method thereof and a burn-resistant test device. BACKGROUND

[0002] The burn-resistant conveying belt is commonly used in the metallurgical and building material industries, and the conveyed materials are generally at 400-600 DEG C, and in extreme cases, above 800 DEG C. In particular, in the steel smelting, the conveyed materials are not only high-temperature but also strong-abrasive, which requires the conveying belt cover rubber to have not only the high-temperature resistance but also the flame resistance, the fast carbonization and the high mechanical strength. At present, the industry generally uses the ethylene-propylene rubber as the main cover rubber, and the service life of the conveying belt is less than 6 months.

[0003] In addition, the reliability and stability of the existing method for evaluating the burn-resistant capability of the conveying belt cover rubber are general, the test process has no fixing device, there are many unstable factors, and the simulation accuracy of the actual working condition is poor.

[0004] Therefore, the burn-resistant conveying belt cover rubber, the preparation method thereof and the burn-resistant test device are provided. SUMMARY

[0005] The application aims at overcoming the defects in the prior art, and provides the burn-resistant conveying belt cover rubber, the preparation method thereof and the burn-resistant test device.

[0006] According to the technical scheme provided by the application, the burn-resistant conveying belt cover rubber comprises the following components in the weight parts: 55-65 parts by weight of hydrogenated nitrile rubber, 35-45 parts by weight of chlorobutyl rubber, 20-30 parts by weight of a composite burn-resistant agent, 40-50 parts by weight of carbon black N330, 8-10 parts by weight of magnesium oxide, 4-8 parts by weight of zinc oxide, 4-5 parts by weight of dicumyl peroxide, 5-8 parts by weight of dioctyl phthalate, 4-6 parts by weight of ammonium polyphosphate, 3-4 parts by weight of antioxidant MB, and the total amount of the hydrogenated nitrile rubber and the chlorobutyl rubber is 100 parts by weight.

[0007] Preferably, the amount of the hydrogenated nitrile rubber is 60 parts by weight, and the amount of the chlorobutyl rubber is 40 parts by weight.

[0008] Preferably, the composite burn-resistant agent is prepared by mixing polyetherimide, aluminum potassium sulfate dodecahydrate and magnesium hydroxide in a weight ratio of 1:2:2.

[0009] The preparation method of the burn-resistant conveying belt cover rubber comprises the following steps: (1) Preparation of composite burn-resistant agent: polyetherimide, aluminum potassium sulfate dodecahydrate and magnesium hydroxide are weighed in a ratio of 1:2:2 by weight, a high-speed dispersing machine is used, the dispersing shaft speed is adjusted to 600-800 r / min, the three raw materials are put into the machine and mixed for 15-20 min for standby; (2) Plasticizing and premixing of raw rubber: hydrogenated nitrile rubber 55-65 parts by weight and chlorobutyl rubber 35-45 parts by weight are weighed for standby, and the total weight of hydrogenated nitrile rubber and chlorobutyl rubber is 100 parts by weight, an open mill is used for plasticizing, the roller speed is adjusted to 20-30 r / min, and the roller distance is adjusted to 0.5-1 mm, the two rubbers are mixed and passed through the mill to form a sheet, and the roller temperature is controlled at 45-60℃; after mixing and passing through the mill for 10 times, the premixed raw rubber is obtained, and the premixed raw rubber is cooled and stored at 10-30℃ for standby; (3) First-stage mixing: 100 parts by weight of the premixed raw rubber is added to the internal mixer, the top bolt is pressed, and the rotor speed of the internal mixer is controlled at 20-25 revolutions per minute; after stirring for 20-30 seconds, the top bolt is opened, 8-10 parts by weight of magnesium oxide, 3-4 parts by weight of antioxidant MB, and 20-30 parts by weight of the composite burn-resistant agent are added to the internal mixer, the top bolt is pressed, and the stirring is continued; after stirring for 30-40 seconds, the top bolt is opened, 40-50 parts by weight of carbon black N330, 5-8 parts by weight of dioctyl phthalate, and 4-6 parts by weight of ammonium polyphosphate are added to the internal mixer, and the stirring is continued for 60-70 seconds; the top bolt is opened, and the first-stage mixed rubber is taken out of the internal mixer; (4) Cooling: the first-stage mixed rubber is cooled to 10-30℃ after being taken out; (5) Second-stage mixing: the cooled first-stage mixed rubber is placed in the internal mixer, 4-8 parts by weight of zinc oxide and 4-5 parts by weight of dicumyl peroxide are added, the top bolt is pressed, the rotor speed of the internal mixer is controlled at 16-20 revolutions per minute, and the stirring is continued for 20-25 seconds; the bottom top bolt is opened, and the second-stage mixed rubber is discharged from the internal mixer; (6) Open mixing: the second-stage mixed rubber is placed in the open mill, the sheet is taken out after 6-8 times of turning, and the sheet is cooled to 10-30℃ after being taken out, thereby obtaining the burn-resistant conveyor belt cover rubber.

[0010] A performance test device for burn-resistant conveyor belt cover rubber, comprising a thermostat, a sample support table, a bearing bracket, a ceramic tube, a cylindrical electric iron, a bearing disc, a weight, and an electric push rod. The thermostat is temperature-adjustable, and the thermostat is fixed by a thermostat bottom plate, a thermostat side plate and a thermostat top plate, the internal space of the thermostat is a cuboid, a side door is arranged on the thermostat side plate, a sample supporting table is fixed on the upper surface of the thermostat bottom plate, the table top of the sample supporting table is square, the center point of the table top of the sample supporting table is located on the longitudinal center line of the internal space of the thermostat, at least three ceramic tube mounting holes are arranged on the thermostat top plate in the range directly above the sample supporting table, the ceramic tube mounting holes are uniformly distributed around the longitudinal center line of the internal space of the thermostat, and one ceramic tube is arranged in each ceramic tube mounting hole, and a cylindrical electric iron is fixed at the lower end of each ceramic tube, and the power line of the cylindrical electric iron is led out of the thermostat through the ceramic tube. The number of the bearing supports is equal to the number of the ceramic tube mounting holes, the bearing support comprises a bearing support vertical rod and a bearing support horizontal rod fixed at the upper end of the bearing support vertical rod, the bearing support vertical rod and the bearing support horizontal rod are vertically arranged, a notch for leading out the power line of the cylindrical electric iron in the ceramic tube is arranged on the bearing support vertical rod, and all the bearing support horizontal rods are uniformly distributed in a radial manner around the longitudinal center line of the internal space of the thermostat. The upper end of the ceramic tube is fixed to the lower end of the bearing support vertical rod, the bearing disc is welded to the inner end of the bearing support horizontal rod, the weight is arranged on the bearing disc, and the electric push rod is arranged on the upper surface of the thermostat top plate below the corresponding bearing disc, and the electric push rod is used for jacking up the bearing support, the ceramic tube, the cylindrical electric iron, the bearing disc and the weight.

[0011] The prepared covering rubber can be used for the fire-resistant conveying belt, solves the problem that the traditional heat-resistant covering rubber is not resistant to material ablation, and the performance reaches the covering layer physical property and fire-resistant performance standard in HG / T 4732 fire-resistant conveying belt, and the stability is more excellent in the test method of the performance test device. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is a structural schematic view of the performance test device of the fire-resistant conveying belt covering rubber in the application. DETAILED DESCRIPTION

[0013] To make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme of the application will be clearly and completely described below in combination with the drawings of the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0014] The raw materials in the following embodiments are all purchased in the market, and specifically are as follows: Hydrogenated nitrile rubber was purchased from Shandong Dawn Polymer Materials Co., Ltd.; Neoprene was purchased from Chongqing Changshou Chemical Co., Ltd.; Zinc oxide was purchased from Shandong Xingya New Materials Co., Ltd. Magnesium oxide was purchased from Hebei Meishen Technology Co., Ltd.; Magnesium hydroxide was purchased from Hebei Meishen Technology Co., Ltd.; Carbon black N330 was purchased from Suzhou Baohua Carbon Black Co., Ltd. Dioctyl phthalate was purchased from Puyang Chengyi Plasticizer Co., Ltd. Antioxidant MB was purchased from Hebi Yuanhao New Materials Group Co., Ltd. Dicumyl peroxide was purchased from Jiangsu Daoming Chemical Co., Ltd.; Polyetherimide was purchased from SABIC Innovative Plastics (China) Co., Ltd.; Potassium aluminum sulfate dodecahydrate was purchased from Jiaozuo Jinji Aluminum Industry Co., Ltd. Ammonium polyphosphate was purchased from Jinan Jinyingtai Chemical Co., Ltd.

[0015] Example 1 A method for preparing a burn-resistant conveyor belt covering rubber, the method comprising the following steps: (1) Preparation of composite anti-burning agent: Weigh polyetherimide, potassium aluminum sulfate dodecahydrate, and magnesium hydroxide in a weight ratio of 1:2:2, use a high-speed disperser, adjust the speed of the dispersion shaft to 600r / min, put the three raw materials into the mixture and mix for 15 minutes.

[0016] (2) Plasticizing and premixing of raw rubber: Weigh 60 parts by weight of hydrogenated nitrile rubber and 40 parts of chloroprene rubber for use, use an open mill to plasticize, adjust the roller speed to 20-30 r / min, adjust the roller distance to 0.5-1 mm, and mix the two rubbers into a thin sheet. Control the roller temperature at 45-60 ° C. After the mixture is thinly passed 10 times, the sheet is produced as a premixed composite raw rubber. Cool it to 10-30 ° C and then use it. (3) One-stage mixing: add 100 parts by weight of premixed composite rubber into the internal mixer, press the top bolt, and control the rotor speed of the internal mixer at 20-25 rpm; after stirring for 20-30 seconds, open the top bolt, add 8 parts by weight of magnesium oxide, 3 parts by weight of antioxidant MB, and 20 parts by weight of composite anti-burning agent into the internal mixer, press the top bolt and continue stirring; after stirring for 30-40 seconds, open the top bolt, add 40 parts by weight of carbon black N330, 5 parts by weight of dioctyl phthalate, and 4 parts by weight of ammonium polyphosphate into the internal mixer, stir for 60-70 seconds, open the top bolt, and take out a section of mixed rubber from the internal mixer; (4) Cooling: After taking out a section of the mixed rubber from the internal mixer, cool it to 10~30℃; (5) Second stage mixing: Place the cooled first stage mixed rubber in an internal mixer, add 4 parts by weight of zinc oxide and 4 parts by weight of dicumyl peroxide, press the top plug and stir, control the rotor speed of the internal mixer at 16-20 rpm, stir for 20-25 seconds, open the bottom plug and discharge the second stage mixed rubber in the internal mixer; (6) Open refining: The second-stage mixed rubber is placed in the open refining mill, and the sheet is produced after the package is turned over 6 to 8 times. After the sheet is produced, it is cooled to 10 to 30 ° C to obtain the burn-resistant conveyor belt covering rubber.

[0017] The physical properties of the burn-resistant conveyor belt covering rubber prepared in Example 1 are shown in Table 1.

[0018] (Physical property test standard HG / T 4732): Table 1

[0019] As can be seen from Table 1, the burn-resistant conveyor belt covering rubber prepared in Example 1 has a tensile strength exceeding that of a conventional heat-resistant covering rubber mainly composed of EPDM rubber (whose tensile strength is not higher than 15 MPa), and its thermal oxidative aging performance and burn resistance meet the requirements of HG / T 4732 standard, and its tensile strength after aging far exceeds the standard requirements.

[0020] Example 2 A method for preparing a burn-resistant conveyor belt covering rubber, the method comprising the following steps: (1) Preparation of composite anti-burning agent: Weigh polyetherimide, potassium aluminum sulfate dodecahydrate, and magnesium hydroxide in a weight ratio of 1:2:2, use a high-speed disperser, adjust the speed of the dispersion shaft to 600r / min, put the three raw materials into the mixture and mix for 15 minutes.

[0021] (2) Plasticizing and premixing of raw rubber: Weigh 60 parts by weight of hydrogenated nitrile rubber and 40 parts of chloroprene rubber for use, use an open mill to plasticize, adjust the roller speed to 20-30 r / min, adjust the roller distance to 0.5-1 mm, and mix the two rubbers into a thin sheet. Control the roller temperature at 45-60 ° C. After the mixture is thinly passed 10 times, the sheet is produced as a premixed composite raw rubber. Cool it to 10-30 ° C and then use it. (3) One-stage mixing: add 100 parts by weight of premixed composite rubber into the internal mixer, press the top bolt, and control the rotor speed of the internal mixer at 20-25 rpm; after stirring for 20-30 seconds, open the top bolt, add 10 parts by weight of magnesium oxide, 4 parts by weight of antioxidant MB, and 30 parts by weight of composite anti-burning agent into the internal mixer, press the top bolt and continue stirring; after stirring for 30-40 seconds, open the top bolt, add 50 parts by weight of carbon black N330, 8 parts by weight of dioctyl phthalate, and 6 parts by weight of ammonium polyphosphate into the internal mixer, stir for 60-70 seconds, open the top bolt, and take out a section of the mixed rubber in the internal mixer; (4) Cooling: the one-stage mixing rubber in the internal mixer is taken out and cooled to 10-30℃; (5) Two-stage mixing: the one-stage mixing rubber after cooling is placed in the internal mixer, 8 parts by weight of zinc oxide and 5 parts by weight of dicumyl peroxide are put in, the ram is pressed to stir, the rotor speed of the internal mixer is controlled at 16-20 revolutions per minute, after stirring for 20-25 seconds, the lower ram is opened, and the two-stage mixing rubber in the internal mixer is discharged; (6) Milling: the two-stage mixing rubber is placed in the mill, and the rubber is turned over 6-8 times to be sheeted out, and the sheeted rubber is cooled to 10-30℃, to obtain the cover rubber for the scorch-resistant conveyor belt.

[0022] The physical properties of the cover rubber for the scorch-resistant conveyor belt prepared in Example 2 are shown in Table 2.

[0023] (Physical property test standard HG / T 4732): Table 2

[0024] As can be seen from Table 2, the tensile strength of the cover rubber for the scorch-resistant conveyor belt prepared in Example 2 exceeds that of the conventional ethylene-propylene rubber-based heat-resistant cover rubber (the tensile strength of which is not higher than 15 MPa), the thermal oxidative aging performance and the scorch resistance meet the requirements of the HG / T 4732 standard, and the tensile strength after aging far exceeds the standard requirements.

[0025] A performance test device for a cover rubber for a scorch-resistant conveyor belt is shown in Figure 1 It comprises a thermostat 1, a sample support table 2, a bearing bracket 3, a ceramic tube 4, a cylindrical electric iron 5, a bearing disc 6, a weight 7 and an electric push rod 8. The thermostat 1 is temperature-adjustable, and is fixed by a thermostat bottom plate, a thermostat side plate and a thermostat top plate. The internal space of the thermostat 1 is a cuboid. A side door is arranged on the thermostat side plate. The sample support table 2 is fixed on the upper surface of the thermostat bottom plate. The table surface of the sample support table 2 is square, and the center point of the table surface is located on the longitudinal center line of the internal space of the thermostat 1. At least three ceramic tube installation holes are arranged on the thermostat top plate in the range directly above the sample support table 2. The ceramic tube installation holes are uniformly distributed around the longitudinal center line of the internal space of the thermostat 1. One ceramic tube 4 is installed in each ceramic tube installation hole. One cylindrical electric iron 5 is fixed at the lower end of each ceramic tube 4. The power line of the cylindrical electric iron 5 is led out of the thermostat 1 through the ceramic tube 4. The number of the bearing supports 3 is equal to the number of the ceramic tube mounting holes, the bearing support 3 comprises a bearing support vertical rod and a bearing support horizontal rod fixed at the upper end of the bearing support vertical rod, the bearing support vertical rod is vertically arranged with the bearing support horizontal rod, a notch for leading out the power line of the cylindrical electric iron 5 in the ceramic tube 4 is arranged on the bearing support vertical rod, and all the bearing support horizontal rods are uniformly distributed in the radial direction around the longitudinal center line of the inner space of the thermostat 1. The upper end of the ceramic tube 4 is fixed with the lower end of the bearing support vertical rod, the bearing disc 6 is welded with the inner end of the bearing support horizontal rod, the weight 7 is arranged on the bearing disc 6, and the electric push rod 8 is arranged on the upper surface of the thermostat top plate below the corresponding bearing disc 6, and the electric push rod 8 is used for jacking up the bearing support 3, the ceramic tube 4, the cylindrical electric iron 5, the bearing disc 6 and the weight 7.

[0026] In the present application, the highest temperature of the thermostat 1 is set to 250℃, the length, width and height of the inner space of the thermostat 1 are 30cm×30cm×20cm, and the diameter of the ceramic tube mounting hole is 21mm. The material of the sample support platform 2 is stainless steel, the height of the sample support platform 2 is 10cm, and the side length of the platform surface of the sample support platform 2 is 20cm. The diameter of the cylindrical electric iron 5 is 20mm, and the length is 50mm, the cylindrical electric iron 5 can control the heating temperature, and the highest heating temperature is set to 800℃. The outer diameter of the ceramic tube 4 is 20mm, the inner diameter is 10mm, and the length is 150mm. The bearing support vertical rod is a cylindrical shape with a diameter of 20mm and a length of 110mm, and the thickness of the bearing support horizontal rod is 20mm and the width is 20mm. The diameter of the bearing disc 6 is 80mm, and the thickness is 5mm. The weight 7 is a standard round cake weight on the market, which is used to adjust the required counterweight (the counterweight includes the weight of the bearing support 3, the ceramic tube 4, the cylindrical electric iron 5, the bearing disc 6 and the weight 7). The maximum stroke of the electric push rod 8 is not less than 50mm.

[0027] The performance test device for the burn-resistant conveyor belt cover rubber in the present application must be equipped with a laser range finder when in use, the laser range finder is a commercially available product, the measurement range of the laser range finder should be not less than 10mm, and the measurement accuracy should be not more than 0.01mm, and the laser range finder is used for measuring the depth of the burned area (ablation thickness) on the surface of the burned conveyor belt.

[0028] The test method based on the performance test device for the burn-resistant conveyor belt cover rubber is as follows: First, a conveyor belt sample (the conveyor belt sample is a cut sample of the conveyor belt, and the conveyor belt sample includes the cover rubber and the belt core below the cover rubber), the size of the conveyor belt sample is 20cm×20cm, and the conveyor belt sample must be adjusted at room temperature for at least 4 hours after being cut; Second, prepare the test device, place the weight 7, adjust the counterweight to 3~15kg (the weight of the weight 7 and the weight of the load support 3, the ceramic tube 4, the cylindrical electric iron 5, and the load plate 6 should be added when calculating the counterweight); Set the temperature of the constant temperature box 1 to 100~250℃, control the electric push rod 8, lift the load support 3, the ceramic tube 4, the cylindrical electric iron 5, the load plate 6 and the weight 7, so that the distance between the lower end of the cylindrical electric iron 5 and the table surface of the sample support 2 is at least 50mm, turn on the cylindrical electric iron 5 to heat to 400~800℃; Third, open the side door of the constant temperature box 1, place the conveyor belt sample on the table surface of the sample support 2, close the side door, and adjust the conveyor belt sample in the constant temperature box 1 for 10~60min; Fourth, lower the electric push rod 8 to the bottom, so that the counterweight is pressed down to the conveyor belt sample under the action of gravity, and keep for 1min~5min; Fifth, lift the electric push rod 8, open the constant temperature box 1, take out the conveyor belt sample, and cool to room temperature.

[0029] Sixth, measure the maximum ablation thickness of each ablation point on the conveyor belt sample by using a laser range finder, and calculate the average value, which is the ablation thickness of the conveyor belt sample.

[0030] The cover rubber obtained in Example 1 is made into a conveyor belt, 12 conveyor belt samples are cut on the conveyor belt, the No. 1-6 conveyor belt samples are burned by using the HG / T 4732 standard, and the No. 7-12 conveyor belt samples are burned by using the above-mentioned test method, and the burning results are shown in Table 3.

[0031] Table 3

[0032] The cover rubber obtained in Example 2 is made into a conveyor belt, 12 conveyor belt samples are cut on the conveyor belt, the No. 1-6 conveyor belt samples are burned by using the HG / T 4732 standard, and the No. 7-12 conveyor belt samples are burned by using the above-mentioned test method, and the burning results are shown in Table 4.

[0033] Table 4

[0034] The ablation test data of Example 1 and Example 2 are combined, and the ablation performance comparison of Table 3 and Table 4 can be seen: the sample standard deviation measured by the test method of the application is smaller than the sample standard deviation of the HG / T 4732 test results, and it can be seen that the test stability and reliability of the test method of the application are better.

[0035] Finally, it should be noted that the above detailed description is merely illustrative of the technical solutions of the present application and is not limiting, and although the present application has been described in detail with reference to the examples, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A burn-resistant conveyor belt covering rubber, characterized by: The invention comprises the following components in parts by weight: 55-65 parts by weight of hydrogenated nitrile rubber, 35-45 parts by weight of chloroprene rubber, 20-30 parts by weight of a composite anti-burning agent, 40-50 parts by weight of carbon black N330, 8-10 parts by weight of magnesium oxide, 4-8 parts by weight of zinc oxide, 4-5 parts by weight of dicumyl peroxide, 5-8 parts by weight of dioctyl phthalate, 4-6 parts by weight of ammonium polyphosphate, and 3-4 parts by weight of an antioxidant MB. The total weight of the hydrogenated nitrile rubber and the chloroprene rubber is 100 parts by weight.

2. The burn-resistant conveyor belt covering rubber according to claim 1, characterized in that: The amount of the hydrogenated nitrile rubber is 60 parts by weight, and the amount of the chloroprene rubber is 40 parts by weight.

3. The burn-resistant conveyor belt covering rubber according to claim 1, characterized in that: The composite anti-burning agent is prepared by mixing polyetherimide, potassium aluminum sulfate dodecahydrate and magnesium hydroxide in a weight ratio of 1:2:

2.

4. The method for preparing the burn-resistant conveyor belt covering rubber according to claim 1, characterized in that The preparation method comprises the following steps: (1) Preparation of composite anti-burning agent: Weigh polyetherimide, potassium aluminum sulfate dodecahydrate and magnesium hydroxide in a weight ratio of 1:2:2, use a high-speed disperser, adjust the speed of the dispersion shaft to 600-800 r / min, put the three raw materials into the mixture and mix for 15-20 minutes; (2) Plasticizing and premixing of raw rubber: Weigh 55-65 parts by weight of hydrogenated nitrile rubber and 35-45 parts by weight of chloroprene rubber for use, and the total weight of hydrogenated nitrile rubber and chloroprene rubber is 100 parts by weight. Use an open mill to plasticize, adjust the roller speed to 20-30 r / min, adjust the roller distance to 0.5-1 mm, and mix the two rubbers into a thin sheet. Control the roller temperature at 45-60 ° C. After the mixture is thinly passed 10 times, the sheet is produced as a premixed composite raw rubber, and is cooled and parked at 10-30 ° C for use. (3) One-stage mixing: add 100 parts by weight of premixed composite rubber into the internal mixer, press the top bolt, and control the rotor speed of the internal mixer at 20-25 rpm; after stirring for 20-30 seconds, open the top bolt, add 8-10 parts by weight of magnesium oxide, 3-4 parts by weight of antioxidant MB, and 20-30 parts by weight of composite anti-burning agent into the internal mixer, press the top bolt and continue stirring; after stirring for 30-40 seconds, open the top bolt, add 40-50 parts by weight of carbon black N330, 5-8 parts by weight of dioctyl phthalate, and 4-6 parts by weight of ammonium polyphosphate into the internal mixer, stir for 60-70 seconds, open the top bolt, and take out a section of the mixed rubber in the internal mixer; (4) Cooling: After taking out a section of the mixed rubber, cool it to 10~30℃; (5) Second stage mixing: Place the cooled first stage mixed rubber in an internal mixer, add 4-8 parts by weight of zinc oxide and 4-5 parts by weight of dicumyl peroxide, press the top plug and stir, control the rotor speed of the internal mixer at 16-20 rpm, stir for 20-25 seconds, open the bottom plug and discharge the second stage mixed rubber in the internal mixer; (6) Open refining: The second-stage mixed rubber is placed in the open refining mill, and the sheet is produced after the package is turned over 6 to 8 times. After the sheet is produced, it is cooled to 10 to 30 ° C to obtain the burn-resistant conveyor belt covering rubber.

5. The performance testing device for the burn-resistant conveyor belt covering rubber according to claim 1 is characterized in that: It comprises a constant temperature box (1), a sample table (2), a supporting bracket (3), a ceramic tube (4), a cylindrical electric soldering iron (5), a supporting plate (6), a weight (7) and an electric push rod (8); The thermostat (1) is a temperature-adjustable type. The thermostat (1) is formed by fixing a thermostat bottom plate, a thermostat side plate and a thermostat top plate. The interior space of the thermostat (1) is a rectangular parallelepiped. A side door is provided on the thermostat side plate. A sample table (2) is fixed on the upper surface of the thermostat bottom plate. The table top of the sample table (2) is square. The center point of the table top of the sample table (2) is located on the longitudinal center line of the interior space of the thermostat (1). At least three ceramic tube mounting holes are opened on the thermostat top plate within the range directly above the sample table (2). The ceramic tube mounting holes are evenly distributed around the longitudinal center line of the interior space of the thermostat (1). A ceramic tube (4) is installed in each ceramic tube mounting hole. A cylindrical electric soldering iron (5) is fixed at the lower end of each ceramic tube (4). The power cord of the cylindrical electric soldering iron (5) is led out of the thermostat (1) through the ceramic tube (4). The number of the supporting brackets (3) is equal to the number of the ceramic tube mounting holes, the supporting brackets (3) include supporting bracket vertical rods and supporting bracket cross rods fixed to the upper ends of the supporting bracket vertical rods, the supporting bracket vertical rods and the supporting bracket cross rods are arranged vertically, a slot for leading out the power cord of the cylindrical electric soldering iron (5) in the ceramic tube (4) is provided on the supporting bracket vertical rods, and all the supporting bracket cross rods are evenly distributed in a radial shape around the longitudinal center line of the internal space of the constant temperature box (1); The upper end of the ceramic tube (4) is fixed to the lower end of the vertical rod of the supporting bracket, the supporting plate (6) is welded to the inner end of the horizontal rod of the supporting bracket, the weight (7) is provided on the supporting plate (6), and the electric push rod (8) is installed on the upper surface of the top plate of the constant temperature box below the corresponding supporting plate (6). The electric push rod (8) is used to lift the supporting bracket (3), the ceramic tube (4), the cylindrical electric soldering iron (5), the supporting plate (6) and the weight (7).

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