Anti-cracking conveyor belt covering rubber and preparation method thereof

Abstract

The present invention discloses a kind of anti-cracking conveyor belt covering rubber and its preparation method, raw materials include: 100 parts of masterbatch, 20-60 parts of reinforcing filler, 1-3 parts of tackifier, 8-25 parts of plasticizer, 2-5 parts of vulcanizer, 7.5-15 parts of vulcanization activator, 4-8 parts of antioxidant; masterbatch includes POR resin and EPDM rubber; reinforcing filler includes white carbon black, carbon black and calcium carbonate; tackifier is zinc methacrylate; plasticizer is p-tert-octylphenol aldehyde; vulcanization activator includes zinc oxide and stearic acid. The present invention adopts the mixed rubber of POR resin and EPDM rubber as the main material of covering rubber, and adjusts the components such as reinforcing filler, tackifier, plasticizer, vulcanization activator, etc. Under the synergistic effect of each component, the anti-cracking performance of covering rubber is improved, and under high temperature environment, covering rubber does not produce cracks, can be used for a long time under 400-600 ℃ environment and can be used for a short time under instantaneous 700 ℃.

Description

Technical Field

[0001] The invention relates to the technical field of conveyor belt covering rubber, in particular to an anti-cracking conveyor belt covering rubber and a preparation method thereof. Background Art

[0002] With the continuous expansion of production scale in metallurgy, building materials and other industries, the requirements for production efficiency are constantly increasing. At the same time, this also puts higher requirements on the performance of conveyor belts, the main components of material transportation in the production of metallurgy and building materials industries.

[0003] The materials transported by the metallurgical (steel) and building materials (cement) industries generally have high temperature characteristics, with temperatures reaching 200~400℃, and the instantaneous temperature even reaching 700℃, so there are high requirements for the heat resistance level of the heat-resistant conveyor belt cover rubber. At present, the heat-resistant conveyor belt cover rubber on the market generally uses styrene-butadiene rubber or EPDM rubber with a heat resistance level of T2~T4, which can meet the transportation of general high-temperature materials. For example, a high-temperature resistant conveyor belt disclosed in the patent with publication number CN101028888A mainly adds EPDM or EPDM into an internal mixer for pre-compression and mixing, then adds a thermal conductor and an anti-aging agent for further mixing; then adds a reinforcing agent, a softener, and aramid staple fibers into the rubber material for mixing to form a first-stage mixed rubber; the mixed rubber is added into an internal mixer for further second-stage mixing, and a cross-linking agent and an auxiliary cross-linking agent are added during the second-stage mixing, and the rubber is discharged after the mixing is uniform; then the above final mixed rubber material is hot-mixed and calendered into a film; the film is bonded to a tensile canvas belt blank to form a finished product after being rolled up, vulcanized, trimmed, and inspected.

[0004] However, in the building materials / steel industry, especially in the steel industry, the material temperature is mostly above 400℃, and the surface of the conveyor belt cover rubber with styrene-butadiene rubber or EPDM as the main material is prone to cracking, which affects material transportation. In order to solve the problem of surface cracking of conveyor belt cover rubber for conveying high-temperature materials in the steel industry, it is particularly urgent to develop an anti-cracking conveyor belt cover rubber. Summary of the invention

[0005] The present invention aims to overcome the problem that the conveyor belt covering rubber in the prior art is prone to cracking when conveying high-temperature materials. A conveyor belt covering rubber with anti-cracking properties and a preparation method thereof are provided. A mixed rubber of POR resin and EPDM rubber is used as the main material of the covering rubber, and components such as reinforcing fillers, tackifiers, plasticizers, and vulcanization activators are adjusted. Under the synergistic effect of the components, the anti-cracking performance of the covering rubber is improved. Under high-temperature conditions, the covering rubber does not crack, can be used for a long time in an environment of 400-600°C, and can be used for a short time at an instantaneous 700°C.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An anti-cracking conveyor belt covering rubber, the raw materials of which include, by weight: 100 parts of masterbatch, 20-60 parts of reinforcing filler, 1-3 parts of tackifier, 8-25 parts of plasticizer, 2-5 parts of vulcanizing agent, 7.5-15 parts of vulcanizing activator, and 4-8 parts of antioxidant;

[0008] The masterbatch comprises POR resin and EPDM rubber in a mass ratio of 40-70:60-30;

[0009] The reinforcing filler comprises white carbon black, carbon black and calcium carbonate in a mass ratio of 2-3:2-3:1;

[0010] The tackifier is zinc methacrylate;

[0011] The plasticizer is p-tert-octylphenolaldehyde BN-1;

[0012] The vulcanization activator comprises zinc oxide and stearic acid in a mass ratio of 6-10:1-5.

[0013] The present invention adopts a mixed rubber of POR resin and EPDM rubber as the main material of the covering rubber; EPDM rubber is a thermoplastic rubber, which is not easy to crack after aging compared with thermosetting styrene-butadiene rubber and EPDM rubber; POR resin is a polyolefin elastomer, which is closer to the rubber state than POE, has excellent strength and elongation performance and tear strength, and has excellent ozone resistance and heat resistance, second only to special synthetic rubbers such as fluorine rubber and silica gel, and has excellent low temperature resistance. Using it as a masterbatch component can further improve the high temperature resistance of the covering rubber and avoid cracking at high temperature. However, the viscosity of POR resin is slightly poor. The present invention overcomes this problem by adding a tackifier zinc methacrylate and a plasticizer p-tert-octylphenol aldehyde BN-1 to form a more solid chemical bond structure, so that the covering rubber has good high temperature resistance and bonding strength at the same time.

[0014] At the same time, the present invention adopts a specific proportion of white carbon black, carbon black and calcium carbonate as reinforcing fillers, and a mixture of zinc oxide and stearic acid as a vulcanization activator, which are combined with the masterbatch to achieve better anti-cracking performance of the covering rubber. Under high temperature environment, the covering rubber does not crack, can be used for a long time under 400-600°C environment and can be used for a short time at 700°C instantaneously, preventing the phenomenon of failure to convey high-temperature materials normally due to cracking of the covering rubber surface caused by excessive temperature, and significantly improving the service life of the conveyor belt under high temperature.

[0015] Preferably, the EPDM rubber is KEP070P.

[0016] Preferably, the carbon black is carbon black N550.

[0017] Preferably, the vulcanizing agent is one or more of di-tert-butyl diisopropyl peroxide, diisopropyl peroxide, and triallyl isocyanurate.

[0018] Preferably, the antioxidant is one or more of antioxidant TMQ, antioxidant 6PPD, and antioxidant MB.

[0019] The present invention also provides a method for preparing the above-mentioned anti-cracking conveyor belt covering rubber, comprising the following steps:

[0020] (1) One-stage mixing: first mix the masterbatch, then add reinforcing filler, vulcanization activator, tackifier, plasticizer and antioxidant, continue mixing, and when the temperature of the mixed material rises to 160-170°C, re-mix it, and after re-mixing, produce a sheet to obtain a one-stage mixed rubber sheet;

[0021] (2) Primary cooling: cooling a section of mixed rubber sheet to obtain a section of mixed rubber;

[0022] (3) Second stage mixing: Mix the first stage mixed rubber and the vulcanizing agent and mix them. When the temperature rises to 105-110°C, re-mix them. After re-mixing, sheets are produced to obtain the second stage mixed rubber.

[0023] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0024] The invention first adds reinforcing filler, vulcanization activator, tackifier, plasticizer and antioxidant into the masterbatch for one-stage mixing and one-stage cooling, and then adds the vulcanizer for two-stage mixing and secondary cooling. Because the discharge temperature of the first-stage mixing is 160-170° C., which is higher than the temperature in the later stage of mixing, the two-stage mixing method is adopted, and the cooling is carried out in two stages. Compared with the one-stage mixing, the quality of the rubber can be improved, the process performance of the rubber has a good effect on improving, and the dispersibility of the rubber and the physical and mechanical properties of the vulcanized rubber are significantly improved.

[0025] Preferably, the masterbatch is mixed for 2 to 3 minutes in step (1); the reinforcing filler, vulcanizing activator, tackifier, plasticizer and antioxidant are added and the mixing is continued for 3 to 5 minutes; the re-mixing time is 3 to 5 minutes; and the sheet thickness is 8 to 10 mm.

[0026] Preferably, the cooling time in step (2) is 8 to 24 hours.

[0027] Preferably, in step (3), the mixing time is 3-4 min, the rolling time is 1-3 min, and the sheet thickness is 6-8 mm.

[0028] Therefore, the present invention has the following beneficial effects:

[0029] (1) The anti-cracking performance of the cover rubber is improved. In high temperature environment, the cover rubber does not crack. It can be used for a long time in an environment of 400~600℃ and can be used for a short time at an instant of 700℃. It prevents the phenomenon of failure to convey high-temperature materials due to cracking and carbonization of the cover rubber surface caused by excessive temperature, and significantly improves the service life of the conveyor belt under high temperature;

[0030] (2) The preparation method is simple and easy to operate. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with specific implementation methods.

[0032] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0033] Overall embodiment:

[0034] An anti-cracking conveyor belt covering rubber, the raw materials of which include, by weight: 100 parts of masterbatch, 20-60 parts of reinforcing filler, 1-3 parts of tackifier, 8-25 parts of plasticizer, 2-5 parts of vulcanizing agent, 7.5-15 parts of vulcanizing activator, and 4-8 parts of antioxidant;

[0035] The masterbatch comprises POR resin and EPDM rubber in a mass ratio of 40-70:60-30;

[0036] The reinforcing filler comprises white carbon black, carbon black and calcium carbonate in a mass ratio of 2-3:2-3:1;

[0037] The tackifier is zinc methacrylate;

[0038] The plasticizer is p-tert-octylphenolaldehyde BN-1;

[0039] The vulcanization activator comprises zinc oxide and stearic acid in a mass ratio of 6-10:1-5.

[0040] As a specific implementation, the EPDM rubber is KEP070P.

[0041] As a specific implementation manner, the carbon black is carbon black N550.

[0042] As a specific implementation, the vulcanizing agent is one or more of di-tert-butyl diisopropyl peroxide, diisopropyl peroxide, and triallyl isocyanurate.

[0043] As a specific implementation manner, the antioxidant is one or more of antioxidant TMQ, antioxidant 6PPD, and antioxidant MB.

[0044] The method for preparing the above-mentioned anti-cracking conveyor belt covering rubber comprises the following steps:

[0045] (1) One-stage mixing: first mix the masterbatch, then add reinforcing filler, vulcanization activator, tackifier, plasticizer and antioxidant, continue mixing, and when the temperature of the mixed material rises to 160-170°C, re-mix it, and after re-mixing, produce a sheet to obtain a one-stage mixed rubber sheet;

[0046] (2) Primary cooling: cooling a section of mixed rubber sheet to obtain a section of mixed rubber;

[0047] (3) Second stage mixing: Mix the first stage mixed rubber and the vulcanizing agent and mix them. When the temperature rises to 105-110°C, re-mix them. After re-mixing, sheets are produced to obtain the second stage mixed rubber.

[0048] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0049] As a specific implementation method, the masterbatch is mixed for 2 to 3 minutes in step (1); the reinforcing filler, vulcanization activator, tackifier, plasticizer and antioxidant are added and then mixed for 3 to 5 minutes; the re-mixing time is 3 to 5 minutes; and the sheet thickness is 8 to 10 mm.

[0050] As a specific implementation manner, the cooling time in step (2) is 8 to 24 hours.

[0051] As a specific implementation method, in step (3), the mixing time is 3 to 4 minutes, the rolling time is 1 to 3 minutes, and the sheet thickness is 6 to 8 mm.

[0052] Embodiment 1:

[0053] A crack-resistant conveyor belt covering rubber comprises, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB.

[0054] The method for preparing the above-mentioned anti-cracking conveyor belt covering rubber comprises the following steps:

[0055] (1) One-stage mixing: 50 parts of POR resin and 50 parts of EPDM rubber KEP070P were put into an internal mixer and mixed for 2.5 minutes; then the top plug was opened, and 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenol BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB were added into the internal mixer, and the top plug was closed and the mixing was continued for 4 minutes. When the temperature of the mixed material in the internal mixer rose to 160°C, the mixing was carried out, and after the mixing, the film was discharged with a thickness of 10 mm to obtain a one-stage mixed film;

[0056] (2) Primary cooling: a section of mixed rubber is placed at room temperature for 16 hours to obtain a section of mixed rubber;

[0057] (3) Second stage mixing: put the first stage mixed rubber, 3 parts of di-tert-butyl diisopropylbenzene peroxide, and 1 part of triallyl isocyanurate into an internal mixer, close the top plug and mix for 3.5 minutes, and re-mix when the temperature in the internal mixer reaches 105°C. After re-mixing, cut into sheets with a thickness of 8 mm to obtain the second stage mixed rubber;

[0058] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0059] Embodiment 2:

[0060] A crack-resistant conveyor belt covering rubber, comprising, by weight, 70 parts of POR resin (purchased from Shaanxi Coal Chemical Technology Research Institute), 30 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 4 parts of diisopropylbenzene peroxide (40wt%), 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 3 parts of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB.

[0061] The method for preparing the above-mentioned anti-cracking conveyor belt covering rubber comprises the following steps:

[0062] (1) One-stage mixing: 70 parts of POR resin and 30 parts of EPDM rubber KEP070P were put into an internal mixer and mixed for 2 minutes; then the top plug was opened, and 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenol BN-1, 3 parts of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB were put into the internal mixer, and the top plug was closed and the mixing was continued for 5 minutes. When the temperature of the mixed material in the internal mixer rose to 160°C, it was re-mixed, and after re-mixing, it was sheeted with a thickness of 10 mm to obtain a one-stage mixed film;

[0063] (2) Primary cooling: a section of mixed rubber is placed at room temperature for 16 hours to obtain a section of mixed rubber;

[0064] (3) Second stage mixing: put the first stage mixed rubber, 4 parts of diisopropylbenzene peroxide (40 wt%) and 1 part of triallyl isocyanurate into an internal mixer, close the top plug and mix for 4 min, and remix when the temperature in the internal mixer reaches 105°C. After remixing, cut into sheets with a thickness of 8 mm to obtain the second stage mixed rubber;

[0065] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0066] Embodiment 3:

[0067] A crack-resistant conveyor belt covering rubber, comprising, by weight, 40 parts of POR resin (purchased from Shaanxi Coal Chemical Technology Research Institute), 60 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 8 parts of p-tert-octylphenolaldehyde BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB.

[0068] The method for preparing the above-mentioned anti-cracking conveyor belt covering rubber comprises the following steps:

[0069] (1) One-stage mixing: 40 parts of POR resin and 60 parts of EPDM rubber KEP070P are put into an internal mixer and mixed for 3 minutes; then the top plug is opened, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 8 parts of p-tert-octylphenol BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB are put into the internal mixer, the top plug is closed and mixing is continued for 3 minutes. When the temperature of the mixed material in the internal mixer rises to 160°C, refining is carried out, and after refining, sheets are produced with a thickness of 10 mm to obtain a one-stage mixed film;

[0070] (2) Primary cooling: a section of mixed rubber is placed at room temperature for 16 hours to obtain a section of mixed rubber;

[0071] (3) Second stage mixing: put the first stage mixed rubber, 3 parts of di-tert-butyl diisopropylbenzene peroxide, and 1 part of triallyl isocyanurate into an internal mixer, close the top plug and mix for 3 minutes, and re-mix when the temperature in the internal mixer reaches 105°C. After re-mixing, cut into sheets with a thickness of 8 mm to obtain the second stage mixed rubber;

[0072] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0073] Embodiment 4:

[0074] A crack-resistant conveyor belt covering rubber, the raw materials of which are measured by weight: 50 parts of POR resin (purchased from Shaanxi Coal Industry Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 30 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 6 parts of zinc oxide, 1.5 parts of stearic acid, 9 parts of p-tert-octylphenol BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 2.5 parts of antioxidant MB;

[0075] The method for preparing the above-mentioned anti-cracking conveyor belt covering rubber comprises the following steps:

[0076] (1) One-stage mixing: 50 parts of POR resin and 50 parts of EPDM rubber KEP070P were put into an internal mixer and mixed for 2.5 minutes; then the top plug was opened, and 30 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 6 parts of zinc oxide, 1.5 parts of stearic acid, 9 parts of p-tert-octylphenol BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 2.5 parts of antioxidant MB were put into the internal mixer, and the top plug was closed and the mixing was continued for 4 minutes. When the temperature of the mixed material in the internal mixer rose to 160°C, it was re-mixed, and after re-mixing, sheets were cut into sheets with a thickness of 10 mm to obtain a one-stage mixed film;

[0077] (2) Primary cooling: a section of mixed rubber is placed at room temperature for 16 hours to obtain a section of mixed rubber;

[0078] (3) Second stage mixing: put the first stage mixed rubber, 3 parts of di-tert-butyl diisopropylbenzene peroxide, and 1 part of triallyl isocyanurate into an internal mixer, close the top plug and mix for 3.5 minutes, and re-mix when the temperature in the internal mixer reaches 105°C. After re-mixing, cut into sheets with a thickness of 8 mm to obtain the second stage mixed rubber;

[0079] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0080] Embodiment 5:

[0081] A crack-resistant conveyor belt covering rubber, the raw materials of which are measured by weight: 50 parts of POR resin (purchased from Shaanxi Coal Industry Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 9 parts of white carbon black, 9 parts of carbon black N550, 3 parts of calcium carbonate, 1 part of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 10 parts of zinc oxide, 5 parts of stearic acid, 25 parts of p-tert-octylphenol BN-1, 1 part of zinc methacrylate, 4 parts of antioxidant TMQ, and 4 parts of antioxidant MB;

[0082] The method for preparing the above-mentioned anti-cracking conveyor belt covering rubber comprises the following steps:

[0083] (1) One-stage mixing: 50 parts of POR resin and 50 parts of EPDM rubber KEP070P were put into an internal mixer and mixed for 2.5 minutes; then the top plug was opened, and 9 parts of white carbon black, 9 parts of carbon black N550, 3 parts of calcium carbonate, 10 parts of zinc oxide, 5 parts of stearic acid, 25 parts of p-tert-octylphenol BN-1, 1 part of zinc methacrylate, 4 parts of antioxidant TMQ, and 4 parts of antioxidant MB were put into the internal mixer, and the top plug was closed and the mixing was continued for 5 minutes. When the temperature of the mixed material in the internal mixer rose to 160°C, it was re-mixed, and after re-mixing, it was sheeted with a thickness of 10 mm to obtain a one-stage mixed film;

[0084] (2) Primary cooling: a section of mixed rubber is placed at room temperature for 16 hours to obtain a section of mixed rubber;

[0085] (3) Second stage mixing: put the first stage mixed rubber, 1 part of di-tert-butyl diisopropylbenzene peroxide, and 1 part of triallyl isocyanurate into an internal mixer, close the top plug and mix for 4 minutes, and re-mix when the temperature in the internal mixer reaches 105°C. After re-mixing, cut into sheets with a thickness of 8 mm to obtain the second stage mixed rubber;

[0086] (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

[0087] Comparative Example 1 (without adding POR resin):

[0088] A crack-resistant conveyor belt covering rubber comprises, by weight, 100 parts of ethylene propylene rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB. The preparation method is the same as that in Example 1.

[0089] Comparative Example 2 (too much POR resin added):

[0090] A crack-resistant conveyor belt covering rubber, comprising, by weight, 80 parts of POR resin (purchased from Shaanxi Coal Chemical Technology Research Institute), 20 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB; the preparation method is the same as that in Example 1.

[0091] Comparative Example 3 (no calcium carbonate added to the reinforcing filler):

[0092] A crack-resistant conveyor belt covering rubber, comprising, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Industry Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 25 parts of white carbon black, 25 parts of carbon black N550, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB; the preparation method is the same as that in Example 1.

[0093] Comparative Example 4 (no white carbon black is added to the reinforcing filler):

[0094] A crack-resistant conveyor belt covering rubber, comprising, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 30 parts of carbon black N550, 20 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB; the preparation method is the same as that in Example 1.

[0095] Comparative Example 5 (without adding tackifier zinc methacrylate):

[0096] A crack-resistant conveyor belt covering rubber, comprising, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Industry Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB; the preparation method is the same as that in Example 1.

[0097] Comparative Example 6 (changing the type of plasticizer):

[0098] A crack-resistant conveyor belt covering rubber, comprising, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Industry Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 8 parts of zinc oxide, 1.5 parts of stearic acid, 9.5 parts of paraffin oil 2280, 1 part of zinc methacrylate, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB; the preparation method is the same as that in Example 1.

[0099] Comparative Example 7 (no zinc oxide is added to the vulcanization activator):

[0100] A crack-resistant conveyor belt covering rubber, comprising, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Industry Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 1 part of zinc methacrylate, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB; the preparation method is the same as that in Example 1.

[0101] Comparative Example 8 (stearic acid is not added to the vulcanization activator):

[0102] A crack-resistant conveyor belt covering rubber comprises, by weight, 50 parts of POR resin (purchased from Shaanxi Coal Chemical Technology Research Institute), 50 parts of EPDM rubber KEP070P, 20 parts of white carbon black, 20 parts of carbon black N550, 10 parts of calcium carbonate, 3 parts of di-tert-butyl peroxide diisopropylbenzene, 1 part of triallyl isocyanurate, 1 part of zinc methacrylate, 9.5 parts of zinc oxide, 9.5 parts of p-tert-octylphenolaldehyde BN-1, 2.5 parts of antioxidant TMQ, and 1.5 parts of antioxidant MB.

[0103] The mechanical properties of the conveyor belt covering rubbers prepared in the above examples and comparative examples were tested, and the results are shown in Table 1.

[0104] Among them, the test method for hardness refers to GB / T 531.1; the test method for tensile properties refers to GB T528-2009; the test method for tearing properties refers to HG / T 2581.1.

[0105] Table 1: Test results of mechanical properties of conveyor belt cover rubber

[0106]

[0107] The conveyor belt covering rubber prepared in the above embodiments and comparative examples was subjected to an anti-cracking test. The experimental method was as follows: a steel ball with a mass of 1.0 kg was placed in an environment with the required temperature for the experiment. After the steel ball was heated to the target temperature and stabilized, it was placed on the sample and kept for 40 seconds. The surface condition was observed. The experimental results are shown in Table 2.

[0108] Table 2: Test results of conveyor belt cover rubber anti-cracking performance

[0109]

[0110] The conveyor belt covering rubbers prepared in the above examples and comparative examples were subjected to aging experiments to test the maximum hardness, tensile strength change rate, and elongation at break change rate at different temperatures. The experimental results are shown in Table 3.

[0111] Table 3: Test results of conveyor belt cover rubber aging performance

[0112]

[0113] It can be seen from Tables 1 to 3 that the covering glue prepared by the formula and method of the present invention in Examples 1 to 5 has good mechanical properties and excellent anti-cracking performance, can be used for a long time in an environment of 400 to 600°C, and can be used for a short time at an instantaneous 700°C.

[0114] In Comparative Example 1, only EPDM rubber was used as the masterbatch without adding POR resin, and the crack resistance and aging resistance of the obtained covering rubber were significantly reduced compared with those in Example 1. In Comparative Example 2, too much POR resin was added, the hardness increased, the tensile strength slightly increased, but the elongation decreased, resulting in excessive changes in the hardness and tensile properties after aging, which is not conducive to the application of the covering rubber.

[0115] In Comparative Examples 3 and 4, no calcium carbonate or white carbon black is added to the reinforcing filler, and the anti-cracking performance and aging resistance of the obtained covering rubber are both reduced compared with those in Example 1, indicating that the type of reinforcing filler has a significant effect on the anti-cracking performance of the covering rubber.

[0116] In Comparative Example 5, no tackifier zinc methacrylate is added, and in Comparative Example 6, a paraffin oil plasticizer commonly used in the art is used instead of the p-tert-octylphenolaldehyde BN-1 in the present invention. The mechanical properties, anti-cracking properties and aging resistance of the obtained covering rubber are all reduced compared with those in Example 1, indicating that the type of plasticizer also has a significant effect on the anti-cracking performance of the covering rubber.

[0117] In Comparative Examples 7 and 8, zinc oxide or stearic acid is not added to the vulcanizing activator, and the anti-cracking performance of the obtained covering rubber is also reduced compared with that in Example 1, indicating that the type of vulcanizing activator also has a significant effect on the anti-cracking performance of the covering rubber.

Claims

1. A crack-resistant conveyor belt covering rubber, characterized in that: In parts by weight, the raw materials include: 100 parts of masterbatch, 20-60 parts of reinforcing filler, 1-3 parts of tackifier, 8-25 parts of plasticizer, 2-5 parts of vulcanizing agent, 7.5-15 parts of vulcanizing activator, and 4-8 parts of antioxidant; The masterbatch comprises POR resin and EPDM rubber in a mass ratio of 40-70:60-30; The reinforcing filler comprises white carbon black, carbon black and calcium carbonate in a mass ratio of 2-3:2-3:1; The tackifier is zinc methacrylate; The plasticizer is p-tert-octylphenolaldehyde BN-1; The vulcanization activator comprises zinc oxide and stearic acid in a mass ratio of 6-10:1-5.

2. The anti-cracking conveyor belt covering rubber according to claim 1 is characterized in that: The EPDM rubber is KEP070P.

3. The anti-cracking conveyor belt covering rubber according to claim 1 is characterized in that: The carbon black is carbon black N550.

4. The anti-cracking conveyor belt covering rubber according to claim 1 is characterized in that: The vulcanizing agent is one or more of di-tert-butyl diisopropylbenzene peroxide, diisopropylbenzene peroxide and triallyl isocyanurate.

5. The anti-cracking conveyor belt covering rubber according to claim 1 is characterized in that: The antioxidant is one or more of antioxidant TMQ, antioxidant 6PPD and antioxidant MB.

6. A method for preparing the anti-cracking conveyor belt covering rubber according to any one of claims 1 to 5, characterized in that: The steps include: (1) One-stage mixing: first mix the masterbatch, then add reinforcing filler, vulcanization activator, tackifier, plasticizer and antioxidant, continue mixing, and when the temperature of the mixed material rises to 160-170°C, re-mix it, and after re-mixing, produce a sheet to obtain a one-stage mixed rubber sheet; (2) Primary cooling: cooling a section of mixed rubber sheet to obtain a section of mixed rubber; (3) Second stage mixing: Mix the first stage mixed rubber and the vulcanizing agent and mix them. When the temperature rises to 105-110°C, refining is performed. After refining, sheets are produced to obtain the second stage mixed rubber. (4) Secondary cooling: Cooling the second-stage mixed rubber to room temperature to obtain the anti-cracking conveyor belt covering rubber.

7. The method for preparing the anti-cracking conveyor belt covering rubber according to claim 6, characterized in that: In step (1), the masterbatch is mixed for 2 to 3 minutes; after adding reinforcing filler, vulcanization activator, tackifier, plasticizer and antioxidant, mixing is continued for 3 to 5 minutes; the refining time is 3 to 5 minutes; and the sheet thickness is 8 to 10 mm.

8. The method for preparing the anti-cracking conveyor belt covering rubber according to claim 6 or 7, characterized in that: The cooling time in step (2) is 8 to 24 hours.

9. The method for preparing the anti-cracking conveyor belt covering rubber according to claim 6, characterized in that: In step (3), the mixing time is 3-4 min, the rolling time is 1-3 min, and the sheet thickness is 6-8 mm.

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