Rubber for underground shovel loader tire and method for producing the same, and underground shovel loader tire

Abstract

The application provides a rubber for underground scraper tires and a preparation method and underground scraper tires. The preparation method of the rubber for underground scraper tires comprises the following steps: S1, mixing vulcanization aids, fillers, rubber and a first solvent to obtain a premixture, continuously feeding the premixture into a reactor for solvent separation to obtain a master batch; S2, after the master batch is densified, adding protective wax and tear-resistant resin for mixing to obtain a first-stage master batch; S3, mixing the first-stage master batch with a first accelerator and a first vulcanizing agent for final mixing to obtain a final mixed rubber; and S4, performing vulcanization treatment on the final mixed rubber to obtain vulcanized rubber. The rubber prepared by the above continuous master batch preparation method has excellent processing performance and mechanical performance, the prepared vulcanized rubber has excellent tensile and tear performance, can adapt to harsh working environments, and is particularly suitable for the preparation of underground scraper tires.

Description

Technical Field

[0001] This invention relates to the field of tire tread rubber technology, and more specifically, to a rubber for underground loader tires and its preparation method, and an underground loader tire. Background Technology

[0002] Underground loaders have large load capacities and operate in extremely harsh environments with uneven working surfaces containing numerous sharp and jagged rocks. The damp underground environment, with mud and water accumulating in low-lying areas, further aggravates the risk of tire cuts and damage due to the lubrication of rock edges. Therefore, underground tires are prone to tread damage such as cuts, chipping, and excessive wear during use. Traditional tire rubber compounding processes are energy-intensive, time-consuming, and generate significant dust pollution, resulting in poor filler dispersion. Increasing filler content is a common method to improve the wear resistance of rubber compounds. However, increasing filler content inevitably increases energy consumption during the mixing process, leading to significant heat generation. Rubber molecules are subjected to intense shearing at high temperatures, making them prone to plasticization and affecting the tensile and tear properties of the compound. High-filler rubber compounds typically also have higher hysteresis loss factors and higher heat generation.

[0003] In recent decades, wet mixing (liquid-phase mixing) technology has developed rapidly. It can reduce the number of mixing stages, lower energy consumption, avoid dust pollution, and solve the problem of poor dispersion of high specific surface area fillers in conventional mixing. However, most wet mixing technologies use latex and filler slurries, followed by chemical coagulation to produce masterbatch. For example, CN106750389 A discloses a wet method for preparing silica / solution-polymerized styrene-butadiene rubber masterbatch. First, silica is uniformly dispersed in an organic solvent, then a silane coupling agent is added to modify the silica. This is then mixed with the solution-polymerized styrene-butadiene rubber solution, and the organic solvent is removed by co-evaporation of water vapor and solvent to obtain the silica / solution-polymerized styrene-butadiene rubber masterbatch. However, the dehydration time is long, and it is only applicable to silica and solution-polymerized styrene-butadiene rubber systems. The paper "Application of Liquid-Phase Mixed NR / Carbon Black Composite Material in Tread Rubber" (Tire Industry, 2005, 25(2):4) discloses the application of carbon black composite material (CEC). The carbon black composite material is produced by Cabot Corporation of the United States using a liquid-phase continuous process to manufacture natural rubber carbon black masterbatch using natural rubber latex and carbon black slurry. This method of preparing rubber filler masterbatch by liquid-phase continuous mixing simplifies the rubber mixing process, mixing time, and reduces energy consumption and labor. However, the types and contents of rubber and fillers used in the preparation of masterbatch are limited, and additives such as masterbatch chemicals still need to be added during the tread rubber mixing process.

[0004] On the other hand, zinc oxide from tire debris entering the water cycle has been proven to cause environmental water pollution. European Commission Directive 2400 / 73 / EC and California's SB1260 bill proposed in 2016 both recommend restricting the use of zinc or zinc oxide in tires. Companies in the rubber and tire industry are facing pressure to transition to green practices and strive to reduce the environmental impact of their production processes. Summary of the Invention

[0005] The main objective of this invention is to provide a rubber for underground loader tires and its preparation method, as well as an underground loader tire, to solve the problems of existing tire tread rubber containing zinc oxide and having tensile and tear properties that are difficult to meet the requirements for use in underground loader tires.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing rubber for underground loader tires is provided, wherein the raw materials for the rubber for underground loader tires include rubber, filler, vulcanization aid, protective wax, tear-resistant resin, first accelerator, and first vulcanizing agent; the filler is carbon black, and the vulcanization aid is an antioxidant and a vulcanization system reagent generated through a pre-reaction process;

[0007] The preparation method of rubber for underground loader tires includes: Step S1, mixing vulcanizing agent, filler, rubber and first solvent to obtain a premix, continuously passing the premix into a reactor for solvent separation to obtain masterbatch; Step S2, after internal mixing of the masterbatch, adding protective wax and tear-resistant resin for compounding to obtain a first-stage masterbatch; Step S3, mixing the first-stage masterbatch with a first accelerator and a first vulcanizing agent for final mixing to obtain a final compound; Step S4, vulcanizing the final compound to obtain vulcanized rubber.

[0008] Furthermore, by weight, the raw materials for the rubber used in the tires of underground loaders include 100 parts of rubber, 30 to 100 parts of filler, 0.5 to 15 parts of vulcanizing agent, 0.5 to 5 parts of protective wax, 0.5 to 20 parts of tear-resistant resin, 0.5 to 5 parts of first accelerator, and 0.5 to 5 parts of first vulcanizing agent.

[0009] Furthermore, the vulcanization auxiliaries are generated by the pre-reaction of antioxidants and vulcanization system chemicals under the action of a catalyst, including stearic acid;

[0010] Preferably, the pre-reaction is carried out in a second solvent, and preferably, the second solvent is any one or more of butanol, octanol, N-methylpyrrolidone, octane, nonane, decane, toluene, and xylene;

[0011] Preferably, the pre-reaction temperature is 100-190 °C and the time is 1 min-120 min;

[0012] More preferably, the pre-reaction temperature is 110-170°C and the time is 5 min-50 min.

[0013] Furthermore, antioxidants include p-phenylenediamine antioxidants;

[0014] Preferably, the antioxidant is a compound having the structure of Formula I:

[0015] Formula I

[0016] In formula I, R 1 Selected from C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 aromatic group, R 2 R 3 R 4 R 5 Selected from C1-C 18 The chain hydrocarbon group, R 2 With R 3 Or R 4 With R 5 They can also form adipose rings individually or simultaneously, R 6 Selected from H, C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 The aromatic group; x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w is 1, and at least one of y and z is 1.

[0017] Furthermore, the filler is carbon black;

[0018] The vulcanization system chemicals include any one or more of the second accelerators;

[0019] The second accelerator includes any one or more of sulfonamide accelerators, sulfenamide accelerators, and thiazole accelerators;

[0020] Preferably, in the pre-reaction process, the amount of antioxidant added is 0.5 to 15 parts by weight, the amount of vulcanizing system chemicals added is 0.5 to 15 parts by weight, and the amount of stearic acid added is 0.5 to 15 parts by weight.

[0021] Furthermore, the catalyst also includes zinc oxide, which is removed by filtration after the pre-reaction is complete.

[0022] Furthermore, the solvent separation methods include any one or more of atmospheric pressure evaporation, low-pressure vacuum drying, heating, spray drying, expansion drying, and flash evaporation;

[0023] Optionally, after solvent separation, the resulting rubber compound is dried to obtain a masterbatch. The drying process includes heat drying and / or mechanical drying.

[0024] Furthermore, the Mooney viscosity ML(1+4)@125℃ of the first-stage masterbatch is less than 65, and preferably, the mixing temperature is 130~170℃ and the time is 2~8min;

[0025] Preferably, the final refining temperature is 80~120℃;

[0026] The vulcanization temperature for the vulcanization treatment is 140~160℃, and the vulcanization time is 0.4~2 hours.

[0027] According to another aspect of the present invention, a rubber for underground loader tires is provided, which is prepared by any of the above-described methods for preparing rubber for underground loader tires.

[0028] According to another aspect of the present invention, an underground loader tire is provided, the underground loader tire comprising the aforementioned rubber for underground loader tires.

[0029] The technical solution of this invention utilizes a vulcanization aid generated through a pre-reaction of an antioxidant and a vulcanization system chemical. This vulcanization aid contains an active intermediate that promotes vulcanization, replacing the role of zinc oxide. It accelerates vulcanization and achieves properties such as crosslinking density, hardness, tensile stress, and hysteresis close to those of zinc-containing rubber compounds. This allows the rubber for underground loader tires prepared in this application to avoid the use of zinc oxide, achieving zinc-free emissions and being more environmentally friendly. Furthermore, the continuous method for preparing masterbatch rubber described above is not only simple and efficient, but also produces rubber compounds with superior processing and mechanical properties. The resulting vulcanized rubber exhibits excellent tensile and tear properties, enabling it to withstand harsh working environments, making it particularly suitable for the preparation of underground loader tires. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0031] As analyzed in the background section of this application, existing technologies suffer from the problem that the tensile and tear properties of rubber are insufficient to meet the requirements of underground loader tires. Furthermore, conventional tread rubber contains zinc oxide, which poses a potential environmental pollution hazard; removing the zinc oxide can easily lead to a decline in the rubber's performance. To address this issue, this application provides a rubber for underground loader tires and a method for its preparation.

[0032] According to a typical embodiment of this application, a method for preparing rubber for underground loader tires is provided. The raw materials for the rubber for underground loader tires include rubber, filler, vulcanizing aid, protective wax, tear-resistant resin, a first accelerator, and a first vulcanizing agent. The filler is carbon black, and the vulcanizing aid is an antioxidant and a vulcanizing system reagent generated through a pre-reaction. The method for preparing the rubber for underground loader tires includes: Step S1, mixing the vulcanizing aid, filler, rubber, and a first solvent to obtain a premix; continuously passing the premix into a reactor for solvent separation to obtain a masterbatch; Step S2, after internal mixing of the masterbatch, adding protective wax and tear-resistant resin for further mixing to obtain a first-stage masterbatch; Step S3, mixing the first-stage masterbatch with the first accelerator and the first vulcanizing agent for final mixing to obtain a final rubber; Step S4, vulcanizing the final rubber to obtain vulcanized rubber.

[0033] The rubber preparation method of this application uses a vulcanization aid generated through a pre-reaction of an antioxidant and a vulcanization system chemical. This vulcanization aid contains an active intermediate that promotes vulcanization and can replace the role of zinc oxide. It can promote vulcanization and obtain properties such as crosslinking density, hardness, tensile stress, and hysteresis close to those of zinc-containing rubber compounds. This allows the rubber for underground loader tires prepared in this application to avoid the use of zinc oxide, achieving zinc-free emissions and being more environmentally friendly. Furthermore, the continuous method for preparing masterbatch rubber described above is not only simple and efficient in process, but also produces rubber compounds with superior processing and mechanical properties. The resulting vulcanized rubber has excellent tensile and tear properties, can withstand harsh working environments, and is particularly suitable for the preparation of underground loader tires.

[0034] In some typical embodiments of this application, the raw materials for the rubber used in the tires of underground loaders include 100 parts by weight, 30-100 parts by weight, 0.5-15 parts by weight, 0.5-5 parts by weight, 0.5-20 parts by weight, 0.5-5 parts by weight, 0.5-5 parts by weight, and 0.5-5 parts by weight, respectively. This allows for better synergistic effects of the components and further improves the performance of the product.

[0035] In some preferred embodiments of this application, the filler is carbon black, and the rubber prepared by the preparation method of this application is more adaptable to the operating environment of underground loader tires.

[0036] In some typical embodiments of this application, the aforementioned vulcanization accelerator is generated by a pre-reaction of an antioxidant and a vulcanization system reagent under the action of a catalyst, wherein the catalyst includes stearic acid. Under the catalytic action of stearic acid, the antioxidant and the vulcanization system reagent can be promoted to react and generate an active intermediate. This active intermediate has the effect of promoting vulcanization, and acts as an early activation accelerator, allowing it to replace the function of zinc oxide.

[0037] To further promote the conversion of antioxidants and vulcanizing agents into active intermediates that promote vulcanization, in some embodiments of this application, the pre-reaction is carried out in a second solvent, allowing the antioxidants, vulcanizing agents, and stearic acid to be dissolved therein, thereby increasing the reaction rate and the conversion rate of the reaction raw materials. Those skilled in the art can select a second solvent from existing technologies, as long as it has no adverse effect on the reaction and can dissolve the antioxidants, vulcanizing agents, and stearic acid involved in the reaction. The amount of the second solvent can be determined based on the specific solvent's solubility in the aforementioned reagents. In some embodiments of this application, the second solvent is any one or more of butanol, octanol, N-methylpyrrolidone, octane, nonane, decane, toluene, and xylene, which have good solubility in the pre-reaction system, no adverse reactions, and are easy to separate and remove subsequently.

[0038] After the pre-reaction is complete, the second solvent can be separated from the product system, or the product solution can be directly mixed with filler, rubber and other components in step S1 and then removed in the solvent separation step.

[0039] In some embodiments of this application, the pre-reaction temperature is 100-190 °C and the time is 1 min-120 min; preferably, the pre-reaction temperature is 110-170 °C and the time is 5 min-50 min, resulting in a higher content of active intermediates in the generated product, which has a more significant promoting effect on the vulcanization of the rubber system. Specifically, the pre-reaction temperature is 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C, 160 °C, 165 °C, etc., but not limited to these; and the reaction time is 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, etc., but not limited to these.

[0040] In some embodiments of this application, the antioxidants described above have a more significant sulfidation promoting effect on the active intermediates generated by the pre-reaction of phenylenediamine antioxidants, and are more likely to react with the pharmaceuticals in the sulfidation system.

[0041] In some preferred embodiments of this application, the antioxidant is a compound having the structure of Formula I. Antioxidants having this structure not only produce better vulcanization effects in vulcanization aids prepared by pre-reaction, but are also more environmentally friendly.

[0042] Formula I

[0043] In formula I, R 1 Selected from C1-C 18chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 aromatic group, R 2 R 3 R 4 R 5 Selected from C1-C 18 The chain hydrocarbon group, R 2 With R 3 Or R 4 With R 5 They can also form adipose rings individually or simultaneously, R 6 Selected from H, C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 The aromatic group; x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w is 1, and at least one of y and z is 1.

[0044] Taking the 2-thiobenzothiazole class of the sulfidation system as an example, the reaction between the antioxidant with Formula I and the sulfidation system drug in the pre-reaction is shown in the following reaction equation. The generated active intermediate has the effect of promoting sulfidation.

[0045]

[0046] In some embodiments of this application, the above-mentioned vulcanization system includes a second accelerator. The second accelerator includes any one or more of sulfonamide accelerators, sulfenamide accelerators, and thiazole accelerators. For example, the second accelerator can be CZ, DZ, DM, M, and NS, but is not limited thereto.

[0047] In some embodiments of this application, the amount of antioxidant added in the pre-reaction is 0.5 to 15 parts by weight, the amount of vulcanizing system chemicals added is 0.5 to 15 parts by weight, and the amount of stearic acid added is 0.5 to 15 parts by weight, resulting in a better effect of the vulcanizing aid.

[0048] In some embodiments of this application, the catalyst further includes zinc oxide, which is removed by filtration after the pre-reaction is complete. Since zinc oxide is practically insoluble in the second solvent, it is easily removed by filtration after the pre-reaction.

[0049] In some embodiments of this application, the pre-reacted product is mixed with rubber to prepare a masterbatch-type vulcanization aid. Preferably, the amount of rubber added is 0-150 phr.

[0050] The specific type of carbon black used as filler in the above-mentioned raw materials can be selected from existing technologies. For example, carbon black can be N115 or N220, but it is not limited to these. Using carbon black as the filler helps ensure the wear resistance and cut resistance of the tread rubber. Preferably, the specific surface area of ​​the carbon black is 10~500 m². 2 / g, more preferably 10~300 m 2 / g, further preferably 100~300 m 2 / g.

[0051] The rubber used in the above-mentioned raw materials can be selected from existing technologies, and this application does not impose any particular limitation. In some embodiments of this application, in order to further improve the adaptability of the tire rubber to the operating environment of underground loader, the rubber is selected from any one or more of natural rubber, polyisoprene rubber, solution polystyrene-butadiene rubber, emulsion polystyrene-butadiene rubber, and polybutadiene rubber. Preferably, the molecular weight of the rubber is 1,000 to 40 million, more preferably 5,000 to 30 million, and even more preferably 10,000 to 8 million.

[0052] The protective wax, tear-resistant resin, first accelerator, and first vulcanizing agent in the raw materials of the rubber for the tires of the aforementioned downhole loaders can all be selected from existing technologies. This application does not have any particular limitations, and they will not be described in detail here. For example, the first vulcanizing agent includes sulfur.

[0053] The aforementioned raw materials may also include other additives, such as oils, antioxidants, coupling agents, activators, antioxidants, heat stabilizers, light stabilizers, flame retardants, dyes, pigments, plasticizers, softeners, and processing aids, one or more of these. Those skilled in the art can add appropriate additives to achieve the desired function based on the specific application environment or requirements of the rubber composition. This application does not impose any particular restrictions on the aforementioned other additives. The dosages of other additives are all conventional dosages, or may be adjusted according to actual requirements.

[0054] In some embodiments of this application, the coupling agent includes any one or more of bis(triethoxypropylsilane)tetrasulfide and disulfide, 3-thiocyanopropyl-triethoxysilane, γ-mercaptopropyl-trimethoxysilane, zirconate coupling agent, phthalate coupling agent and nitro coupling agent.

[0055] In some embodiments of this application, the softener includes any one or more of aromatic oils and tackifying resins, and is used in an amount of 0 to 30 parts by weight, preferably 0 to 20 parts by weight. In particular, when the rubber contains styrene-butadiene rubber, the amount of softener in the raw material is not zero. Adding a softener to styrene-butadiene rubber can further improve the processing performance of the rubber compound.

[0056] In some embodiments of this application, the first solvent is selected from any one or more of aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, chlorinated hydrocarbon solvents, ketone solvents, ether solvents, and ester solvents. For example, aliphatic hydrocarbon solvents include, but are not limited to, various solvent gasolines, cycloalkanes and substituted cycloalkanes, and n-alkanes; aromatic hydrocarbon solvents include, but are not limited to, benzene, toluene, xylene, and styrene; and chlorinated hydrocarbon solvents include, but are not limited to, dichloromethane, trichloromethane, carbon tetrachloride, dichloroethane, chlorobenzene, tetrachloroethylene, and chlorotoluene.

[0057] In some preferred embodiments of this application, the rubber is mixed with the first solvent to form a homogeneous rubber solution, and then the vulcanizing aid and filler are mixed with the rubber solution to make the premix more homogeneous. In some embodiments of this application, the concentration of rubber in the rubber solution is 1% to 60% by weight, preferably 5% to 40% by weight, and more preferably 10% to 30% by weight, which helps to improve the homogeneity of the premix and saves solvent usage as much as possible, thus reducing energy consumption.

[0058] In some embodiments of this application, the solvent separation methods include any one or more of atmospheric pressure evaporation, spray drying, expansion drying, low-pressure vacuum drying, flash evaporation, and heating. Specifically, if atmospheric pressure evaporation is used for solvent separation, evaporation can be performed using an oven or drying plate. If spray drying is used for solvent separation, the atomization method can be centrifugal atomization, pressure atomization, or two-fluid atomization. If expansion drying is used for solvent separation, heating can be performed first, followed by a sudden release of pressure. If flash evaporation is used for solvent separation, at least one of atmospheric pressure flash evaporation or reduced pressure flash evaporation can be used, with 1-3 flash stages. If low-pressure vacuum drying is used for solvent separation, specifically, the solvent is evaporated or filtered under vacuum to a pressure below one atmosphere, with the pressure ranging from -0.1 MPa to 0, preferably from -0.09 MPa to 0, and more preferably from -0.08 MPa to 0. The above solvent separation methods can be combined to achieve the purpose of solvent separation.

[0059] In some embodiments of this application, the above-mentioned expansion drying is to flash vaporize the solvent using a screw expansion dryer. Preferably, the screw expansion dryer pushes along the shaft at 0-20 MPa, more preferably 1-10 MPa, with decreasing screw pitch, generating heat through friction, causing a sudden drop in outlet pressure, relaxing the expansion of the rubber strip, and flash vaporizing the solvent inside the rubber strip.

[0060] In some embodiments of this application, after solvent separation, the obtained rubber compound is dried to obtain a masterbatch. The drying after solvent separation is mainly to take into account the situation where the solvent separation in the rubber compound is incomplete. For example, when the solid content in the rubber compound after solvent separation is less than 98 wt%, drying is beneficial to further improve the performance of the final tire rubber product.

[0061] The drying process described above includes heat drying and / or mechanical drying. Specifically, heat drying can be oven drying or air drying. Mechanical drying is performed using an open mill, kneader, internal mixer, or screw extruder, with an operating temperature of 20 ℃-250 ℃.

[0062] In step S2 above, the masterbatch is thoroughly mixed to ensure that the vulcanizing aid, filler and rubber are mixed evenly. Preferably, the mixing temperature is 130~170℃ and the time is 2~8min, which helps to fully utilize the role of the vulcanizing aid and further improve the crosslinking density of the rubber.

[0063] Adding protective wax and tear-resistant resin during the mixing process helps improve the dispersion of fillers in the rubber.

[0064] In some embodiments of this application, in order to further improve the processing performance of the rubber compound, the Mooney viscosity ML(1+4)@125℃ of the first masterbatch is less than 65. If the first masterbatch after mixing does not meet this requirement, the rubber compound can be re-mixed. The re-mixing process is the same as the initial mixing.

[0065] Preferably, the mixing temperature is 130~170℃. Specifically, the mixing temperature can be 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, etc., or other values ​​within the above range. Adding accelerators and vulcanizing agents during the final mixing process helps to prevent scorching of the final rubber.

[0066] In some preferred embodiments of this application, the final tempering temperature is 80~120℃ and the time is 1~6 min. Specifically, the final tempering temperature is 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc., and the final tempering time is 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, etc. The final tempering temperature and time can also be other values ​​within the above range.

[0067] In some typical embodiments of this application, the vulcanization temperature of the above-mentioned vulcanization treatment is 140~160°C and the vulcanization time is 0.4~2 hours, which helps to further improve the tear resistance of the rubber used in the tires of underground loader.

[0068] According to another typical embodiment of this application, a rubber for underground loader tires is provided, which is prepared by any of the above-described methods for preparing rubber for underground loader tires.

[0069] The rubber for underground loader tires disclosed in this application utilizes a vulcanization auxiliary generated through a pre-reaction process of an antioxidant and vulcanization system chemicals. This auxiliary contains an active intermediate that promotes vulcanization, replacing the role of zinc oxide. It accelerates vulcanization, achieving properties such as crosslinking density, hardness, tensile stress, and hysteresis close to those of zinc-containing rubber compounds. This allows the rubber for underground loader tires prepared in this application to avoid the use of zinc oxide, achieving zinc-free emissions and being more environmentally friendly. Furthermore, the continuous method for preparing the masterbatch used in this application is not only simple and efficient, but also produces rubber compounds with superior processing and mechanical properties. The resulting vulcanized rubber exhibits excellent tensile and tear resistance properties, enabling it to withstand harsh working environments, making it particularly suitable for the manufacture of underground loader tires.

[0070] According to another typical embodiment of this application, an underground loader tire is provided, the tire containing the above-described rubber for underground loader tires.

[0071] Because the rubber used in the aforementioned underground loader tires has excellent tensile and tear resistance properties, it can better adapt to the harsh underground environment and has no zinc emissions, making it environmentally friendly, the underground loader tire of this application also has good performance and is environmentally friendly, thus having good prospects for use and promotion.

[0072] The beneficial effects that this application can achieve will be further illustrated below with reference to embodiments and comparative examples.

[0073] The specific sources of the materials used in the embodiments and comparative examples of this application are as follows:

[0074] Styrene-butadiene rubber, ESBR1502, TSRC Corporation;

[0075] Carbon black: N234, Shanghai Cabot Co., Ltd.; specific surface area 119 m² 2 / g, oil absorption value 125mL / 100g;

[0076] Stearic acid, a product of Tyco Brown Chemical (Zhangjiagang) Co., Ltd.

[0077] Protective wax, a product of Qingdao Jinxian Chemical Co., Ltd.

[0078] Antioxidant RD, a product of Nanjing Chemical Industry Co., Ltd., China Petrochemical Corporation;

[0079] Antioxidant 4020, a product of Jiangsu Shengao Chemical Technology Co., Ltd.

[0080] Tear-resistant resin, Jiangsu Qixiang High-Tech Materials Co., Ltd.;

[0081] Accelerator CZ, a product of Shandong Shangshun Chemical Co., Ltd.

[0082] DPG accelerator, a product of Shandong Shangshun Chemical Co., Ltd.

[0083] Sulfur, a product of Liaoning Chaoyang Tianming Industry and Trade Co., Ltd.

[0084] Example 1

[0085] 1) Preparation of vulcanizing aid: Mix 4 parts by weight of zinc oxide, 1 part by weight of stearic acid, and 3 parts by weight of environmentally friendly antioxidant. 1.2 parts by weight of accelerator CZ were mixed in nonane, pre-reacted at 160 °C for 40 min, restored to room temperature, filtered to remove zinc, and the filtrate was used to obtain zinc-free sulfidation aid.

[0086] 2) The above-mentioned zinc-free vulcanizing aid and 60 parts by weight of carbon black N234 were added to 100 parts by weight of ESBR1502 in n-hexane solution. After mixing, the mixture was continuously injected into the reactor for spray drying to separate the solvent, and then vacuum dried to obtain masterbatch A.

[0087] 3) Add masterbatch A to the internal mixer and mix for 1 minute. Then add 1 part by weight of protective wax and 10 parts by weight of tear-resistant resin. Mix for 3 minutes and discharge the mixture at 150°C to obtain a first-stage compound. The Mooney viscosity ML(1+4)@125°C of this compound is 55.

[0088] 4) After the first batch of rubber compound has been left to stand for 8 hours, add 1.5 parts by weight of accelerator DPG and 1.7 parts by weight of sulfur to the internal mixer, mix for 2 minutes, and then discharge the rubber at 100°C to obtain the final rubber compound.

[0089] 5) After the final compound has been left to stand for 8 hours, it is vulcanized at 150 °C for 40 minutes using a flat vulcanizing machine to obtain continuous vulcanized rubber A.

[0090] Example 2

[0091] The difference from Example 1 is that zinc oxide is not added during the preparation of the zinc-free vulcanizing aid.

[0092] Example 3

[0093] The difference from Example 1 is that in step 3), the discharge temperature of the compound is 125°C and the time is 2 min. The Mooney viscosity ML(1+4)@125°C of the compound obtained after compounding is 75. After re-compounding for 3 min, the compound is discharged at 150°C. The Mooney viscosity ML(1+4)@125°C of the compounded rubber after re-compounding is 60.

[0094] Example 4

[0095] The difference from Example 3 is that no remelting was performed in step 3).

[0096] Comparative Example 1

[0097] In a Banbury mixer, 60 parts by weight of carbon black N234 were added to 100 parts by weight of ESBR1502 and mixed for 1 minute. Then, 4 parts by weight of zinc oxide, 1 part by weight of stearic acid, 1.5 parts by weight of antioxidant 4020, 1.5 parts by weight of antioxidant RD, 1 part by weight of protective wax, and 10 parts by weight of tear-resistant resin were added and mixed for 3 minutes. The mixture was discharged at 150°C. After the mixture was left to stand for 8 hours, 1.2 parts by weight of accelerator CZ, 1.5 parts by weight of accelerator DPG, and 1.7 parts by weight of sulfur were added to the Banbury mixer and mixed for 2 minutes. The mixture was discharged at 100°C. After the mixture was left to stand for 8 hours, it was vulcanized at 150°C for 40 minutes using a flat vulcanizing machine to obtain dry vulcanized rubber.

[0098] The vulcanizates prepared in the above examples and comparative examples were tested according to the following methods, and the test results are listed in Table 1.

[0099] The filler dispersion grade was determined according to GB / T 6030-2006 Rapid Comparative Method for Evaluation of Carbon Black and Carbon Black / Silica Dispersion in Rubber;

[0100] The physical properties (tensile strength and elongation at break) of the rubber compound were determined in accordance with GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0101] The vulcanization characteristics of rubber compounds were determined according to GB / T 16584-1996 "Determination of vulcanization characteristics using a rotorless vulcanizing apparatus for rubber".

[0102] The hardness of the rubber compound was determined according to GB / T 531.1-2008 Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore hardness tester method (Shore hardness)

[0103] The elastic modulus of the rubber compound at 60°C was determined according to GB / T 9870.1-2006 Determination of dynamic properties of vulcanized rubber or thermoplastic rubber - Part 1: General rules, and the dynamic properties of the rubber compound were determined using a rotational rheometer.

[0104] Table 1

[0105]

[0106] By comparing the physical and dynamic properties of the tread rubbers obtained by the continuous preparation process and the dry preparation process in Examples and Comparative Example 1, it can be seen that under similar main ingredient formulations, the continuous preparation process improves the dispersion of fillers in the rubber, resulting in excellent tensile properties of the vulcanizate, while also significantly improving hardness and DIN abrasion.

[0107] Furthermore, this application achieved properties similar to those of rubber compounds containing zinc oxide by adding a vulcanizing agent that does not contain zinc. The vulcanized rubber A obtained in Examples 1-4 was used for the tread of underground loader tires. The zinc content in the rubber compound was determined according to the inductively coupled plasma atomic emission spectrometry method for the determination of lead, cadmium, chromium, copper, manganese and zinc content in rubber and its products, proving that there was no zinc emission.

[0108] In addition, extraction experiments were conducted on the tire wear debris from Examples 1-4, and HRMS analysis of the extract confirmed that the self-synthesized environmentally friendly antioxidant does not produce highly toxic quinone compounds. Toxicity testing of the extract confirmed that the environmentally friendly antioxidant is less toxic to zebrafish and silver salmon than commercial antioxidants such as 4020 (6PPD), and is environmentally friendly.

[0109] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: The rubber preparation method uses an antioxidant and a vulcanization auxiliary generated through a pre-reaction of the vulcanization system chemicals. This vulcanization auxiliary contains an active intermediate that promotes vulcanization, which can replace the role of zinc oxide. It can promote vulcanization and obtain properties such as crosslinking density, hardness, tensile stress, and hysteresis close to those of zinc-containing rubber compounds. This allows the rubber for underground loader tires prepared in this application to avoid the use of zinc oxide, achieving zinc-free emissions and being more environmentally friendly. Furthermore, the continuous method for preparing masterbatch rubber described above is not only simple and efficient in its preparation process, but also produces rubber compounds with superior processing and mechanical properties. The resulting vulcanized rubber has excellent tensile and tear properties, can adapt to harsh working environments, and is particularly suitable for the preparation of underground loader tires.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing a rubber for a downhole dragline tire, characterized by, The raw material of the downhole shovel loader tire rubber comprises rubber, filler, vulcanization aid, protective wax, tear-resistant resin, first accelerator and first vulcanizing agent; the filler is carbon black; the vulcanization aid is generated by pre-reaction of antioxidant and vulcanization system medicine under the action of catalyst; wherein the catalyst comprises stearic acid; the antioxidant is p-phenylenediamine antioxidant; the pre-reaction temperature is 100-190°C, and the time is 1 min-120 min; the vulcanization system medicine comprises second accelerator, and the second accelerator is selected from any one or more of CZ, DZ, DM, M and NS; The preparation method of the downhole shovel loader tire rubber comprises: Step S1, mixing vulcanization aid, filler, rubber and first solvent to obtain a premix, continuously feeding the premix into a reactor for solvent separation to obtain masterbatch; Step S2, after the masterbatch is densified, protective wax and tear-resistant resin are added for mixing to obtain a first-stage masterbatch; Step S3, the first-stage masterbatch is mixed with first accelerator and first vulcanizing agent for final mixing to obtain a final mixed rubber; Step S4, the final mixed rubber is subjected to vulcanization treatment to obtain vulcanized rubber; In the pre-reaction, the antioxidant is added in an amount of 0.5-15 parts by weight, the vulcanization system medicine is added in an amount of 0.5-15 parts by weight, and the stearic acid is added in an amount of 0.5-15 parts by weight.

2. The method for preparing rubber for underground loader tires according to claim 1, characterized in that, The raw material of the downhole shovel loader tire rubber comprises rubber 100 parts, filler 30-100 parts, vulcanization aid 0.5-15 parts, protective wax 0.5-5 parts, tear-resistant resin 0.5-20 parts, first accelerator 0.5-5 parts and first vulcanizing agent 0.5-5 parts by weight.

3. The method for preparing rubber for underground loader tires according to claim 1, characterized in that, The pre-reaction is carried out in a second solvent, and the second solvent is any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene and xylene; and / or the pre-reaction temperature is 110-170°C, and the time is 5 min-50 min.

4. The method for preparing rubber for underground loader tires according to claim 1, characterized in that, The antioxidant is a compound having the structure of formula I: Formula I In formula I, R 1 Selected from C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 aromatic group, R 2 R 3 R 4 R 5 Selected from C1-C 18 The chain hydrocarbon group, R 2 With R 3 Or R 4 With R 5 They can also form adipose rings individually or simultaneously, R 6 Selected from H, C1-C 18 chain hydrocarbon group, C3-C 18 alicyclic hydrocarbon group or C6-C 18 The aromatic group; x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w is 1, and at least one of y and z is 1.

5. The method of claim 1, wherein the downhole dragline tire rubber is prepared by the steps of: The catalyst further comprises zinc oxide, and the zinc oxide is removed by filtration after the pre-reaction is completed.

6. The method of claim 1, wherein the downhole dragline tire rubber is prepared by the steps of: The solvent separation method comprises any one or more of atmospheric evaporation, low-pressure vacuum drying, heating, spray drying, expansion drying and flash evaporation.

7. The method for preparing rubber for underground loader tires according to claim 6, characterized in that, After the solvent separation, the obtained rubber is subjected to drying treatment to obtain the first-stage masterbatch, and the drying treatment comprises heating drying and / or mechanical drying.

8. The method for preparing rubber for underground loader tires according to claim 1, characterized in that, The Mooney viscosity ML(1+4)@125°C of the first-stage masterbatch is lower than 65; The vulcanization temperature of the vulcanization treatment is 140-160°C, and the vulcanization time is 0.4-2 hours.

9. The method for preparing rubber for underground loader tires according to claim 8, characterized in that, The mixing temperature is 130-170°C, and the time is 2-8 min.

10. The method for preparing rubber for underground loader tires according to claim 8, characterized in that, The final mixing temperature is 80-120°C.

11. A rubber for a downhole scraper tire, characterized by, Prepared by the preparation method of the downhole shovel loader tire rubber according to any one of claims 1-10.

12. A downhole dragline tire characterized by, Containing the downhole shovel loader tire rubber according to claim 11.

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