Rubber compound for T4-grade heat-resistant conveyor belt covering layer and preparation method of rubber compound

Abstract

The invention discloses a rubber compound for a T4-grade heat-resistant conveyor belt covering layer and a preparation method of the rubber compound, and belongs to the technical field of heat-resistant conveyor belts. The rubber compound is prepared from ethylene propylene rubber, polyisobutene, an active flowable agent, an anti-aging agent, a reinforcing agent, a plasticizer, a heat-resistant reinforcing agent, a vulcanizing agent, an assistant crosslinker and the like. The main body base material adopts low Mooney / medium-high ethylene content and high Mooney / high ethylene content ethylene-propylene rubber, and the molecular chain of the base material is completely saturated; an active lubricant zinc laurate is added to reduce the Mooney viscosity of the rubber compound and improve the processability, and polyisobutene is added to further reduce the Mooney viscosity of the rubber compound and improve the autohension of the rubber compound; the anti-aging agent RD, the anti-aging agent MB and the anti-aging agent GS are combined according to a certain proportion, and through synergistic cooperation, the protection effect is excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat-resistant conveyor belts, and in particular relates to a rubber compound for a T4-grade heat-resistant conveyor belt covering layer and a preparation method thereof. Background Art

[0002] Heat-resistant conveyor belts primarily consist of a cover, a belt core, and edge rubber. They are widely used in industries such as metallurgy, coking, and building materials to transport high-temperature materials such as sintered ore, coke, and cement clinker. Currently, performance evaluation of heat-resistant conveyor belts in my country is primarily based on the national standard GB / T 20021-2017, "Canvas Core Heat-Resistant Conveyor Belts." This standard categorizes heat-resistant conveyor belts into four grades, with T4 being the highest heat-resistant grade. This requires that the cover rubber maintain certain physical and mechanical properties after aging at 180°C for 168 hours.

[0003] With the expansion of my country's industrial production scale and the improvement of efficiency, the temperature of materials transported by heat-resistant conveyor belts continues to rise. The short-term temperature of the material can reach above 400°C, and the long-term operating temperature can reach 180°C. The T4-level heat-resistant conveyor belt covering rubber on the market is mostly based on EPDM rubber. The main chain of EPDM rubber is saturated but the side chain contains unsaturated double bonds. It can only be used briefly or intermittently at 180°C. The long-term operating performance deteriorates seriously and the service life is short. The covering layer is prone to cracking, delamination, blistering and other problems under high temperature conditions, which will cause damage to the conveyor belt, affect material transportation, increase enterprise costs, and fail to meet the current increasingly stringent working conditions.

[0004] EPDM rubber is a copolymer of ethylene and propylene. Its main chain is fully saturated. EPDM with high Mooney and ethylene content has long-term high-temperature aging resistance significantly superior to EPDM. However, EPDM with high Mooney and ethylene content has poor processing performance, and the resulting compound exhibits poor self-adhesion, making it difficult to use in production.

[0005] Existing T4-grade heat-resistant conveyor belts suffer from cracking, delamination, and blistering during operation due to the poor heat resistance of the cover rubber. This damages the belt, hinders material transportation, increases company costs, and fails to meet the increasingly stringent operating requirements. While EPDM rubber offers better heat resistance than EPDM, its processing performance is poor. The resulting mix exhibits poor self-adhesion, prevents proper roller wrapping, and prevents continuous sheet production, making it difficult to use in conveyor belt production. Summary of the Invention

[0006] The present invention aims to provide a rubber mix for a T4-grade heat-resistant conveyor belt covering layer and a preparation method thereof. The rubber mix comprises EPDM rubber, polyisobutylene, an active flow agent, an antioxidant, a reinforcing agent, a plasticizer, a heat-resistant enhancer, a vulcanizing agent, a cross-linking aid, and the like. The main substrate uses a combination of low-Mooney / medium-high ethylene content and high-Mooney / high ethylene content EPDM rubber, and the molecular chains of the substrate are completely saturated. The active lubricant zinc laurate is added to reduce the Mooney viscosity of the rubber mix and improve the processing performance. The addition of polyisobutylene further reduces the Mooney viscosity of the rubber mix and improves the self-adhesion of the rubber mix. The antioxidant RD, the antioxidant MB, and the antioxidant GS are combined in a certain proportion and synergistically cooperate to achieve excellent protective effects.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A T4 grade heat-resistant conveyor belt cover rubber compound comprises the following raw materials in parts by weight: 30-60 parts of EPDM rubber A, 40-70 parts of EPDM rubber B, 5-10 parts of tackifier, 3-6 parts of active lubricant, 2-4 parts of antioxidant, 13-16 parts of heat-resistant enhancer, 40-50 parts of reinforcing agent, 15-20 parts of plasticizer, 6-10 parts of vulcanizing agent, and 2-5 parts of cross-linking agent.

[0008] A method for preparing a rubber compound for a T4-grade heat-resistant conveyor belt cover layer comprises the following steps: Step 1: Put EPDM rubber A, EPDM rubber B, tackifier, active lubricant, antioxidant and heat-resistant enhancer into an internal mixer, mix for 40-60 seconds at a speed of 35-45r / min, a temperature of 120-130℃ and a top bolt pressure of 0.5-0.7MPa, then add reinforcing agent and plasticizer, continue mixing for 40-60 seconds, and continuously extruder the sheets through a roller head extruder, pass through a release agent tank, and cool to room temperature in a wind room. Let it stand for 8-12 hours to obtain a masterbatch.

[0009] Step 2: Put the masterbatch into an internal mixer, mix for 30-40 seconds at a speed of 20-30 r / min, a temperature of 100-110°C and a top bolt pressure of 0.5-0.7 MPa, add a vulcanizing agent and a cross-linking agent, and continue mixing for 120-150 seconds. To ensure uniform mixing, lift the bolt 2-3 times during the mixing process, and continuously extruder the masterbatch through a roller head extruder. After passing through a release agent tank, cool it to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

[0010] Furthermore, EPDM rubbers A and B are composed of two EPDM rubbers with different Mooney values ​​and ethylene contents, wherein EPDM rubber A is a low Mooney / medium-high ethylene content EPDM rubber with a Mooney viscosity of 40-45 [(1+4)100°C] and an ethylene content of 55-65%; EPDM rubber B is a high Mooney / high ethylene content EPDM rubber with a Mooney viscosity of 65-80 [(1+4)100°C] and an ethylene content of 65-75%.

[0011] Furthermore, the specific preparation steps of the heat-resistant enhancer are as follows: Glass micro-nanospheres, terephthalic acid and N,N-dimethylformamide are added to a polytetrafluoroethylene-lined reactor, stirred at 20-25°C and 500-600 r / min for 20-30 minutes, then cerium oxide and lanthanum oxide are added, heated to 120-130°C, stirred for 24-26 hours, cooled naturally to room temperature, filtered, and the filter cake is washed with N,N-dimethylformamide and methanol for 2-4 times respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain a heat-resistant enhancer.

[0012] Furthermore, the usage ratio of the glass micro-nanospheres, terephthalic acid, N,N-dimethylformamide, cerium oxide and lanthanum oxide is 50-60 g: 50-60 g: 800-900 mL: 20-30 g: 20-30 g.

[0013] Furthermore, the specific preparation steps of glass micro-nanospheres are as follows: Hexadecyltrimethylammonium bromide, ammonia water and 30-40% ethanol solution by mass were added into a reactor, stirred at 20-25°C and 500-600 r / min for 20-30 min, then tetraethoxysilane, triethyl phosphate and zinc nitrate were added, stirring was continued for 6-7 h, filtered, and the filter cake was washed with deionized water 2-4 times, vacuum dried at 60-70°C for 1-2 h, calcined at 650-700°C in an air atmosphere for 3-4 h, and naturally cooled to room temperature to obtain glass micro-nanospheres.

[0014] Furthermore, the usage ratio of hexadecyltrimethylammonium bromide, ammonia water, ethanol solution, tetraethoxysilane, triethyl phosphate and zinc nitrate is 12-14 g: 8-10 mL: 400-500 mL: 136-145 mL: 13-14 mL: 50-60 g.

[0015] Furthermore, the tackifier is polyisobutylene with a molecular weight of 900-3000.

[0016] Furthermore, the active lubricant is zinc laurate.

[0017] Furthermore, the antioxidant is a mixture of antioxidant RD, antioxidant MB (2-mercaptobenzimidazole), and antioxidant GS (2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate).

[0018] Furthermore, the reinforcing agent is one of carbon black N220 and carbon black N330, or a mixture of the two.

[0019] Furthermore, the plasticizer is high flash point paraffin oil PLAXENE 25110, and the open cup flash point is greater than 310°C.

[0020] Furthermore, the vulcanizing agent is DCP-40, the content of dicumyl peroxide is about 40%, and the carrier is light calcium carbonate or precipitated silica.

[0021] Furthermore, the auxiliary cross-linking agent is a mixture of TAIC (triallyl isocyanurate) and zinc acrylate.

[0022] Beneficial effects of the present invention: 1. The present invention provides a rubber compound for a T4-grade heat-resistant conveyor belt cover, which is composed of EPDM rubber, polyisobutylene, an active flow agent, an antioxidant, a reinforcing agent, a plasticizer, a heat-resistant enhancer, a vulcanizing agent, a cross-linking aid, etc. The main substrate is a combination of low-Mooney / medium-high ethylene content and high-Mooney / high ethylene content EPDM rubber, and the molecular chain of the substrate is completely saturated; the Mooney viscosity of the rubber compound is reduced by adding an active lubricant zinc laurate to improve the processing performance; the Mooney viscosity of the rubber compound is further reduced by adding polyisobutylene, while the self-adhesiveness of the rubber compound is improved; the antioxidant RD, the antioxidant MB, and the antioxidant GS are combined in a certain proportion, and through synergistic cooperation, an excellent protective effect is achieved.

[0023] 2. The heat-resistant enhancer of the present invention uses glass micro-nanospheres generated from silica as a carrier, and hydrothermally synthesizes a metal skeleton structure of bimetallic coordination of cerium and lanthanum on the surface. The heat-resistant enhancer can react with unstable groups in rubber molecules or active free radicals generated during thermal aging through Lewis acid action, adsorb and neutralize free radicals through coordination, block the chain transmission of oxidation reactions, improve the thermal stability of molecular chains, and delay the high-temperature decomposition process; the glass micro-nanosphere structure of the heat-resistant enhancer can effectively inhibit heat conduction, protect the core under the covering layer, and at the same time play a good reinforcing role on rubber, thereby improving the physical properties of the rubber after vulcanization.

[0024] 3. The rubber compound produced by the above technical means not only solves the technical problems of poor processing performance of EPDM rubber, inability to wrap rollers normally, and inability to continuously produce sheets; at the same time, after ultra-long-term high-temperature aging at 180°C for 504 hours, the vulcanized rubber still has no problems such as cracking and blistering on the surface, and still has good flexibility and maintains good physical properties. The T4-level heat-resistant conveyor belt prepared with this rubber compound also solves the technical problem that the current heat-resistant conveyor belt with EPDM rubber as the main base material cannot be used for a long time under 180°C working conditions. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Example 1: A method for preparing a rubber compound for a T4 grade heat-resistant conveyor belt cover layer, comprising the following steps: S1: Add 12 g of hexadecyltrimethylammonium bromide, 8 mL of ammonia water and 400 mL of 30% ethanol solution into the reactor, stir at 20 ° C and 500 r / min for 20 min, then add 136 mL of tetraethoxysilane, 13 mL of triethyl phosphate and 50 g of zinc nitrate, continue stirring for 6 h, filter, wash the filter cake twice with deionized water, vacuum dry at 60 ° C for 1 h, calcined at 650 ° C for 3 h in air atmosphere, and naturally cooled to room temperature to obtain glass micro-nanospheres.

[0027] S2: Add 50g of glass micro-nanospheres, 50g of terephthalic acid and 800mL of N,N-dimethylformamide into a polytetrafluoroethylene-lined reactor, stir at 20°C and 500r / min for 20min, then add 20g of cerium oxide and 20g of lanthanum oxide, heat to 120°C, continue stirring for 24h, cool naturally to room temperature, filter, wash the filter cake with N,N-dimethylformamide and methanol twice respectively, and dry in vacuum at 60°C for 1h to obtain a heat-resistant enhancer.

[0028] S3: 30 parts of EPDM rubber A, 70 parts of EPDM rubber B, 10 parts of polyisobutylene, 5 parts of active lubricant zinc laurate, 1 part of antioxidant RD, 1.5 parts of antioxidant MB, 1.5 parts of antioxidant GS and 13 parts of heat-resistant enhancer were put into an internal mixer and mixed for 40 seconds at a speed of 35 r / min, a controlled temperature of 120°C and a top bolt pressure of 0.5 MPa. Then, 30 parts of reinforcing agent N220, 20 parts of reinforcing agent N330 and 10 parts of plasticizer PLAXENE 25110 were added and mixing was continued for 40 seconds. The mixture was continuously extruded through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in a wind room. The mixture was allowed to stand for 8 hours to obtain a masterbatch.

[0029] S4: The masterbatch was put into an internal mixer and mixed for 30 seconds at a speed of 20 r / min, a controlled temperature of 100°C and a top bolt pressure of 0.5 MPa. 7 parts of vulcanizing agent DCP-40 and 1.5 parts of co-crosslinking agent TAIC were added and the mixing was continued for 120 seconds. To ensure uniform mixing, the bolt was lifted twice during the mixing process. The sheets were continuously extruded through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

[0030] Example 2: A method for preparing a rubber compound for a T4 grade heat-resistant conveyor belt cover layer, comprising the following steps: S1: Add 13 g of hexadecyltrimethylammonium bromide, 9 mL of ammonia water and 450 mL of 35% ethanol solution into the reactor, stir at 22.5 ° C and 550 r / min for 25 min, then add 140.5 mL of tetraethoxysilane, 13.5 mL of triethyl phosphate and 55 g of zinc nitrate, continue stirring for 6.5 h, filter, wash the filter cake with deionized water three times, vacuum dry at 65 ° C for 1.5 h, calcined at 675 ° C for 3.5 h in air atmosphere, and naturally cooled to room temperature to obtain glass micro-nanospheres.

[0031] S2: Add 55g of glass micro-nanospheres, 55g of terephthalic acid and 850mL of N,N-dimethylformamide into a polytetrafluoroethylene-lined reactor, stir at 22.5°C and 550r / min for 25min, then add 25g of cerium oxide and 25g of lanthanum oxide, heat to 125°C, continue stirring for 25h, cool naturally to room temperature, filter, wash the filter cake with N,N-dimethylformamide and methanol three times respectively, and dry in vacuo at 65°C for 1.5h to obtain a heat-resistant enhancer.

[0032] S3: 45 parts of EPDM rubber A, 55 parts of EPDM rubber B, 10 parts of polyisobutylene, 5 parts of active lubricant zinc laurate, 1.5 parts of antioxidant RD, 1.5 parts of antioxidant MB, 1 part of antioxidant GS, and 14 parts of heat-resistant enhancer were put into an internal mixer and mixed for 50 seconds at a speed of 38 r / min, a controlled temperature of 123°C, and a top bolt pressure of 0.6 MPa. Then, 25 parts of reinforcing agent N220, 25 parts of reinforcing agent N330, and 15 parts of plasticizer PLAXENE 25110 were added and mixing was continued for 50 seconds. The mixture was continuously extruded through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in a wind room. The mixture was allowed to stand for 9 hours to obtain a masterbatch.

[0033] S4: The masterbatch was put into an internal mixer and mixed for 30 seconds at a speed of 20 r / min, a controlled temperature of 100°C and a top bolt pressure of 0.6 MPa. 8 parts of vulcanizing agent DCP-40, 1.5 parts of co-crosslinking agent TAIC and 4 parts of co-crosslinking agent zinc acrylate were added and the mixing was continued for 128 seconds. To ensure uniform mixing, the bolt was lifted twice during the mixing process. The sheets were continuously discharged through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

[0034] Example 3: A method for preparing a rubber compound for a T4 grade heat-resistant conveyor belt cover layer, comprising the following steps: S1: Add 14 g of hexadecyltrimethylammonium bromide, 10 mL of ammonia water and 500 mL of 40% ethanol solution into the reactor, stir at 25 ° C and 600 r / min for 30 min, then add 145 mL of tetraethoxysilane, 14 mL of triethyl phosphate and 60 g of zinc nitrate, continue stirring for 7 h, filter, wash the filter cake with deionized water 4 times, vacuum dry at 70 ° C for 2 h, calcined at 700 ° C for 4 h in an air atmosphere, and naturally cooled to room temperature to obtain glass micro-nanospheres.

[0035] S2: Add 60g of glass micro-nanospheres, 60g of terephthalic acid and 900mL of N,N-dimethylformamide into a polytetrafluoroethylene-lined reactor, stir at 25°C and 600r / min for 30min, then add 30g of cerium oxide and 30g of lanthanum oxide, heat to 130°C, continue stirring for 26h, cool naturally to room temperature, filter, wash the filter cake with N,N-dimethylformamide and methanol four times respectively, and dry in vacuo at 70°C for 2h to obtain a heat-resistant enhancer.

[0036] S3: 60 parts of EPDM rubber A, 40 parts of EPDM rubber B, 10 parts of polyisobutylene, 6 parts of active lubricant zinc laurate, 1.5 parts of antioxidant RD, 1.5 parts of antioxidant MB, 1.5 parts of antioxidant GS and 16 parts of heat-resistant enhancer are put into an internal mixer, mixed for 60 seconds at a speed of 45 r / min, a controlled temperature of 130°C and a top bolt pressure of 0.7 MPa, and then 20 parts of reinforcing agent N220 and 30 parts of reinforcing agent N330 are added, and mixing is continued for 60 seconds. The sheets are continuously discharged through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in a wind room. The sheets are allowed to stand for 12 hours to obtain a masterbatch.

[0037] S4: The masterbatch was put into an internal mixer and mixed for 40 seconds at a speed of 30 r / min, a controlled temperature of 110°C and a top bolt pressure of 0.7 MPa. 8 parts of vulcanizing agent DCP-40, 1.5 parts of co-crosslinking agent TAIC and 3 parts of co-crosslinking agent zinc acrylate were added and the mixing was continued for 150 seconds. To ensure uniform mixing, the bolt was lifted 3 times during the mixing process. The sheets were continuously discharged through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

[0038] Comparative Example 1: A method for preparing a rubber compound for a T4 grade heat-resistant conveyor belt cover layer, comprising the following steps: S1: 60 parts of EPDM rubber A, 40 parts of EPDM 4045, 5 parts of polyisobutylene, 6 parts of active lubricant zinc laurate, 1.5 parts of antioxidant RD and 1.5 parts of antioxidant MB were put into an internal mixer and mixed for 40 seconds at a speed of 36 r / min, a temperature of 129°C and a push bolt pressure of 0.7 MPa. Then, 20 parts of reinforcing agent N220 and 30 parts of reinforcing agent N330 were added and mixed for another 40 seconds. The mixture was continuously extruded through a roller die extruder, passed through a release agent tank, and then cooled to room temperature in a wind room. The mixture was allowed to stand for 8 hours to obtain a masterbatch.

[0039] S2: The masterbatch was put into an internal mixer and mixed for 39 seconds at a speed of 30 r / min, a temperature of 110°C and a top bolt pressure of 0.7 MPa. 8 parts of vulcanizing agent DCP-40, 1.5 parts of co-crosslinking agent TAIC and 3 parts of co-crosslinking agent zinc acrylate were added and the mixing was continued for 150 seconds. To ensure uniform mixing, the bolt was lifted 3 times during the mixing process. The sheets were continuously extruded through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

[0040] Comparative Example 2: A method for preparing a rubber compound for a T4-grade heat-resistant conveyor belt cover, comprising the following steps: S1: Add 14 g of hexadecyltrimethylammonium bromide, 10 mL of ammonia water and 500 mL of 40% ethanol solution into the reactor, stir at 25 ° C and 600 r / min for 30 min, then add 145 mL of tetraethoxysilane, 14 mL of triethyl phosphate and 60 g of zinc nitrate, continue stirring for 7 h, filter, wash the filter cake with deionized water 4 times, vacuum dry at 70 ° C for 2 h, calcined at 700 ° C for 4 h in an air atmosphere, and naturally cooled to room temperature to obtain glass micro-nanospheres.

[0041] S2: Add 60g of glass micro-nanospheres, 60g of terephthalic acid and 900mL of N,N-dimethylformamide into a polytetrafluoroethylene-lined reactor, stir at 25°C and 600r / min for 30min, then add 30g of cerium oxide and 30g of lanthanum oxide, heat to 130°C, continue stirring for 26h, cool naturally to room temperature, filter, wash the filter cake with N,N-dimethylformamide and methanol four times respectively, and dry in vacuo at 70°C for 2h to obtain a heat-resistant enhancer.

[0042] S3: 60 parts of EPDM rubber A, 40 parts of EPDM 4045, 5 parts of polyisobutylene, 6 parts of active lubricant zinc laurate, 1.5 parts of antioxidant RD, 1.5 parts of antioxidant MB, 1.5 parts of antioxidant GS and 16 parts of heat-resistant enhancer were put into an internal mixer, mixed for 60 seconds at a speed of 45 r / min, a temperature of 130°C and a top bolt pressure of 0.7 MPa, and then 20 parts of reinforcing agent N220 and 30 parts of reinforcing agent N330 were added and mixed for another 60 seconds. The mixture was continuously extruded through a roller die extruder, cooled to room temperature in a wind room after passing through a release agent tank, and allowed to stand for 12 hours to obtain a masterbatch.

[0043] S4: The masterbatch was put into an internal mixer and mixed for 40 seconds at a speed of 30 r / min, a temperature of 110°C and a top bolt pressure of 0.7 MPa. 8 parts of vulcanizing agent DCP-40, 1.5 parts of co-crosslinking agent TAIC and 3 parts of co-crosslinking agent zinc acrylate were added and the mixing was continued for 150 seconds. To ensure uniform mixing, the bolt was lifted 3 times during the mixing process. The sheets were continuously discharged through a roller head extruder, passed through a release agent tank, and then cooled to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

[0044] Performance tests were performed on Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 1.

[0045] As shown in Table 1, the changes in physical and mechanical properties of the rubber mixes prepared in Examples 1, 2, and 3 and Comparative Examples 1 and 2 after aging at 180°C for 168 hours all met the requirements for cover layer rubber materials for T4-grade heat-resistant conveyor belts as specified in GB / T 20021-2017. However, after long-term aging, Comparative Examples 1 and 2 exhibited significant performance degradation after 504 and 336 hours of high-temperature aging, respectively. In particular, Comparative Example 2, which uses EPDM rubber, experienced a significant performance decline after 336 hours of aging, and after 504 hours of aging, the rubber material had completely hardened and cracked. Examples 1, 2, and 3 maintained excellent physical and mechanical properties even after 504 hours of high-temperature aging, significantly improving the aging resistance of the cover layer for T4-grade heat-resistant conveyor belts.

[0046] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a rubber compound for a T4 grade heat-resistant conveyor belt cover, characterized in that: The following steps are involved: Step 1: Put EPDM rubber A, EPDM rubber B, tackifier, active lubricant, antioxidant and heat-resistant enhancer into an internal mixer, mix for 40-60 seconds at a speed of 35-45 r / min, a temperature of 120-130°C and a top bolt pressure of 0.5-0.7 MPa, then add reinforcing agent and plasticizer, continue mixing for 40-60 seconds, and continuously extruder the sheets through a roller die, pass through a release agent tank, and then cool to room temperature in a wind room and stand for 8-12 hours to obtain a masterbatch; Step 2: Put the masterbatch into an internal mixer, mix for 30-40 seconds at a speed of 20-30 r / min, a temperature of 100-110°C and a top bolt pressure of 0.5-0.7 MPa, add a vulcanizing agent and a cross-linking agent, and continue mixing for 120-150 seconds. To ensure uniform mixing, lift the bolt 2-3 times during the mixing process, and continuously extruder the masterbatch through a roller head extruder. After passing through a release agent tank, cool it to room temperature in an air room to obtain a T4 grade heat-resistant conveyor belt cover rubber compound.

2. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 1, characterized in that: The EPDM rubbers A and B are composed of two EPDM rubbers with different Mooney values ​​and ethylene contents, wherein the EPDM rubber A is a low Mooney / medium-high ethylene content EPDM rubber with a Mooney viscosity of 40-45 [(1+4)100°C] and an ethylene content of 55-65%; the EPDM rubber B is a high Mooney / high ethylene content EPDM rubber with a Mooney viscosity of 65-80 [(1+4)100°C] and an ethylene content of 65-75%.

3. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 1, characterized in that: The specific preparation steps of the heat-resistant enhancer are as follows: Glass micro-nanospheres, terephthalic acid and N,N-dimethylformamide are added to a polytetrafluoroethylene-lined reactor, stirred at 20-25°C and 500-600 r / min for 20-30 minutes, then cerium oxide and lanthanum oxide are added, heated to 120-130°C, stirred for 24-26 hours, cooled naturally to room temperature, filtered, and the filter cake is washed with N,N-dimethylformamide and methanol for 2-4 times respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain a heat-resistant enhancer.

4. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 3, characterized in that: The usage ratio of the glass micro-nanospheres, terephthalic acid, N,N-dimethylformamide, cerium oxide and lanthanum oxide is 50-60g:50-60g:800-900mL:20-30g:20-30g.

5. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 3, characterized in that: The specific preparation steps of the glass micro-nanospheres are as follows: Hexadecyltrimethylammonium bromide, ammonia water and 30-40% ethanol solution by mass were added into a reactor, stirred at 20-25°C and 500-600 r / min for 20-30 min, then tetraethoxysilane, triethyl phosphate and zinc nitrate were added, stirring was continued for 6-7 h, filtered, and the filter cake was washed with deionized water 2-4 times, vacuum dried at 60-70°C for 1-2 h, calcined at 650-700°C in an air atmosphere for 3-4 h, and naturally cooled to room temperature to obtain glass micro-nanospheres.

6. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 5, characterized in that: The usage ratio of hexadecyltrimethylammonium bromide, ammonia water, ethanol solution, tetraethoxysilane, triethyl phosphate and zinc nitrate is 12-14 g: 8-10 mL: 400-500 mL: 136-145 mL: 13-14 mL: 50-60 g.

7. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 1, characterized in that: The tackifier is polyisobutylene with a molecular weight of 900-3000; the active lubricant is zinc laurate.

8. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 1, characterized in that: The antioxidant is a mixture of antioxidant RD, antioxidant MB (2-thiol benzimidazole), and antioxidant GS (2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate).

9. The method for preparing a T4 grade heat-resistant conveyor belt cover rubber compound according to claim 1, characterized in that: The reinforcing agent is one or a mixture of carbon black N220 and carbon black N330; the plasticizer is high-flash point paraffin oil PLAXENE 25110 with an open cup flash point greater than 310°C; the vulcanizing agent is DCP-40 with a dicumyl peroxide content of approximately 40%; the carrier is light calcium carbonate or precipitated silica; and the co-crosslinking agent is a mixture of TAIC and zinc acrylate.

10. A rubber compound for a T4 grade heat-resistant conveyor belt cover, comprising the following raw materials in parts by weight: 30-60 parts of EPDM rubber A, 40-70 parts of EPDM rubber B, 5-10 parts of tackifier, 3-6 parts of active lubricant, 2-4 parts of antioxidant, 13-16 parts of heat-resistant enhancer, 40-50 parts of reinforcing agent, 15-20 parts of plasticizer, 6-10 parts of vulcanizing agent, and 2-5 parts of cross-linking agent.

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