Rubber for underground carry-scraper tire, preparation method of rubber and underground carry-scraper tire

Abstract

The invention provides rubber for an underground carry-scraper tire, a preparation method of the rubber and the underground carry-scraper tire. The preparation method of the rubber for the underground carry-scraper tire comprises the following steps: S1, mixing a vulcanizing aid, a filler, rubber and a first solvent to obtain a pre-mixture, and continuously introducing the pre-mixture into a reactor for solvent separation to obtain a rubber master batch; s2, after the master batch is internally mixed, protective wax and tear-resistant resin are added for mixing, and first-section master batch is obtained; s3, mixing the primary masterbatch with a first accelerant and a first vulcanizing agent, and performing final mixing to obtain final mixed rubber; and S4, performing vulcanization treatment on the final mixed rubber to obtain vulcanized rubber. The rubber material prepared by the method for continuously preparing the master batch has excellent processability and mechanical property, and the prepared vulcanized rubber has excellent tensile property, tearing property and the like, can adapt to harsh working environments, and is particularly suitable for preparing underground carry-scraper tires.

Description

Technical Field

[0001] The present invention relates to the technical field of tread rubber, and in particular to a rubber for underground scraper tire, a preparation method thereof, and an underground scraper tire. Background Art

[0002] Underground scrapers have a large load capacity and a very harsh working environment. The working surface is bumpy and there are a lot of sharp gravel. At the same time, the underground environment is humid, and there is mud and water in the depressions for a long time. The lubrication of the edges of the stones increases the risk of tire cuts and damage. Therefore, the tread of underground tires is prone to cuts, chipping, excessive wear and other damage during use. The traditional tire rubber mixing process is energy-consuming, time-consuming, and dust-prone, and the filler dispersion is poor. Increasing the amount of filler is a common means to improve the wear resistance of the rubber. Increasing the amount of filler will inevitably increase the energy consumption during the mixing process, generate more heat during mixing, and the rubber molecules are subjected to strong shear at high temperatures. They are easily plasticized, affecting the tensile and tearing properties of the rubber. Highly filled rubbers usually have higher hysteresis loss factors and heat generation.

[0003] In recent decades, wet mixing (liquid phase mixing) technology has developed rapidly, which can reduce the number of mixing stages, reduce energy consumption, avoid dust pollution, and solve the problem that high specific surface area fillers are not easy to disperse in conventional mixing. However, most wet mixing technologies use latex and filler slurry, and then produce masterbatch by chemical coagulation. For example, CN106750389A discloses a method for preparing white carbon black / solution polymerized styrene butadiene rubber masterbatch by wet method, firstly dispersing white carbon black in an organic solvent, adding a silane coupling agent to modify white carbon black, and then mixing with solution polymerized styrene butadiene rubber glue solution, removing organic solvent by water vapor and solvent co-evaporation, and obtaining white carbon black / solution polymerized styrene butadiene rubber masterbatch. However, the dehydration time is long, and it is only applied to white carbon black and solution polymerized styrene butadiene rubber system. "Application of Liquid-phase Mixed NR / Carbon Black Composites in Tread Rubber" (Tire Industry, 2005, 25(2):4) discloses the application of carbon black composites (CEC). The carbon black composites are prepared by Cabot Corporation of the United States using natural rubber latex and carbon black slurry in a liquid phase continuous process for manufacturing natural rubber carbon black masterbatch. This method of preparing rubber filler masterbatch by liquid phase continuous mixing simplifies the mixing process and mixing time, reduces energy consumption and labor, but the types and contents of rubber and fillers used in the preparation of the 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 in tire debris enters the water circulation system and has been proven to cause environmental water pollution. The European Commission Directive 2400 / 73 / EC and the SB1260 bill proposed by California in 2016 both recommend limiting the use of zinc or zinc oxide in tires. Companies in the rubber tire industry are facing pressure to transform to a green environment and are committed to reducing the impact of the production process on the environment. Summary of the invention

[0005] The main purpose of the present invention is to provide a rubber for underground scraper tires and a preparation method thereof, and underground scraper tires, so as to solve the problem that the tread rubber in the prior art contains zinc oxide and the tensile and tearing properties are difficult to meet the use requirements of underground scraper tires.

[0006] In order to achieve the above-mentioned object, according to one aspect of the present invention, a method for preparing rubber for underground scraper tires is provided, wherein the raw materials of the rubber for underground scraper tires include rubber, filler, vulcanization aid, protective wax, tear-resistant resin, a first accelerator and a first vulcanizing agent; the filler is carbon black, and the vulcanization aid is generated by pre-reaction of an antioxidant and a vulcanization system drug;

[0007] The preparation method of rubber for underground scraper tires comprises: step S1, mixing a vulcanizing agent, a filler, a rubber and a first solvent to obtain a premix, and continuously passing the premix into a reactor for solvent separation to obtain a masterbatch; step S2, mixing the masterbatch, adding protective wax and tear-resistant resin for mixing to obtain a masterbatch; step S3, mixing the masterbatch with a first accelerator and a first vulcanizing agent, and performing final mixing to obtain a final mixed rubber; step S4, vulcanizing the final mixed rubber to obtain a vulcanized rubber.

[0008] Furthermore, in parts by weight, the raw materials of rubber for underground scraper tires include 100 parts of rubber, 30 to 100 parts of filler, 0.5 to 15 parts of vulcanizing aid, 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 aid is generated by pre-reaction of an antioxidant and a vulcanization system drug under the action of a catalyst, and the catalyst includes 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] Further, the antioxidant is a p-phenylenediamine antioxidant;

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

[0015]

[0016] In Formula I, R 1 Selected from C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 The aromatic hydrocarbon 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 aliphatic rings separately or simultaneously, R 6 Selected from H, C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w has a value of 1, and at least one of y and z has a value of 1.

[0017] Further, 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 a sulfonamide accelerator, a sulfenamide accelerator, and a thiazole accelerator;

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

[0021] Furthermore, the catalyst also includes zinc oxide, and after the preliminary reaction is completed, the zinc oxide is filtered out.

[0022] Further, the method of solvent separation includes any one or more of atmospheric pressure evaporation, low pressure vacuum drying, heating, spray drying, expansion drying and flash evaporation;

[0023] Optionally, after the solvent is separated, the obtained rubber material is dried to obtain a masterbatch, and the drying process includes heating drying and / or mechanical drying.

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

[0025] Preferably, the final refining temperature is 80-120°C;

[0026] The vulcanization temperature of the vulcanization treatment is 140 to 160° C., and the vulcanization time is 0.4 to 2 hours.

[0027] According to another aspect of the present invention, there is provided a rubber for underground scraper tire, which is prepared by any one of the above-mentioned methods for preparing the rubber for underground scraper tire.

[0028] According to another aspect of the present invention, there is provided an underground scraper tire, the underground scraper tire containing the above-mentioned rubber for underground scraper tire.

[0029] The technical solution of the present invention is applied, and a vulcanization aid generated by pre-reaction of an antioxidant and a vulcanization system drug is used. The vulcanization aid contains an active intermediate that promotes vulcanization, which can replace the role of zinc oxide, promote vulcanization, and obtain cross-linking density, hardness, tensile stress and hysteresis properties close to those of zinc-containing rubber. The rubber for underground scraper tires prepared by the present application can avoid the use of zinc oxide, achieve zinc-free emissions, and be more environmentally friendly. In addition, the present application uses the above-mentioned continuous method for preparing a masterbatch, which not only has a simple and efficient preparation process, but also has excellent processing performance and mechanical properties of the prepared rubber. The prepared vulcanized rubber has excellent tensile and tearing properties, can adapt to harsh working environments, and is particularly suitable for the preparation of underground scraper tires. DETAILED DESCRIPTION

[0030] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0031] As analyzed in the background technology of this application, the existing technology has the problem that the tensile and tearing properties of rubber are difficult to meet the use requirements of underground scraper tires, and the conventional tread rubber contains zinc oxide, which has the hidden danger of environmental pollution. If the zinc oxide is removed, the performance of the rubber will be easily reduced. In order to solve this problem, this application provides a rubber for underground scraper tires and a preparation method thereof.

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

[0033] In the rubber preparation method of the present application, a vulcanization aid generated by pre-reaction of an antioxidant and a vulcanization system drug is used. The vulcanization aid contains an active intermediate that promotes vulcanization, which can replace the role of zinc oxide, promote vulcanization, and obtain cross-linking density, hardness, tensile stress and hysteresis properties close to those of zinc-containing rubber. The rubber for underground scraper tires prepared by the present application can avoid the use of zinc oxide, achieve zinc-free emissions, and be more environmentally friendly. In addition, the present application uses the above-mentioned continuous method for preparing masterbatch, which not only has a simple and efficient preparation process, but also the prepared rubber has excellent processing performance and mechanical properties. The prepared vulcanized rubber has excellent tensile and tearing properties, can adapt to harsh working environments, and is particularly suitable for the preparation of underground scraper tires.

[0034] In some typical embodiments of the present application, the raw materials of rubber for underground scraper tires include, by weight, 100 parts, 30 to 100 parts of filler, 0.5 to 15 parts of vulcanizing aid, 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, which can better exert the synergistic effect of each component and further improve the performance of the product.

[0035] In some preferred embodiments of the present application, the filler is carbon black, and the rubber prepared by the preparation method of the present application has better adaptability to the use environment of underground scraper tires.

[0036] In some typical embodiments of the present application, the above-mentioned vulcanization aid is generated by pre-reaction of an antioxidant and a vulcanization system drug 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 drug can be promoted to react to generate an active intermediate, which has the effect of promoting vulcanization and plays the role of activating the accelerator in advance, so that the active intermediate can replace the role of zinc oxide.

[0037] In order to further promote the conversion of antioxidant and vulcanization system medicine into active intermediates with promotion of vulcanization, in some embodiments of the present application, the above-mentioned pre-reaction is carried out in the second solvent, so that antioxidant, vulcanization system medicine and stearic acid can be solvent therein, improve the conversion rate of reaction rate and reaction raw materials. Those skilled in the art can select the second solvent from the prior art, as long as there is no adverse effect on the reaction, and the antioxidant, vulcanization system medicine and stearic acid participating in the reaction can be dissolved, and the amount of the second solvent can be determined according to the solubility of the above-mentioned reagents according to the specific solvent type. In some embodiments of the present application, the second solvent is any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene, and dimethylbenzene, which is better for the solubility of the pre-reaction system, and has no adverse reaction, and is also convenient for separation and removal later.

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

[0039] In some embodiments of the present application, the temperature of the pre-reaction is 100-190°C, and the time is 1min-120min; preferably, the temperature of the pre-reaction is 110-170°C, and the time is 5min-50min, the content of active intermediates in the generated product is higher, and the effect of promoting the vulcanization of the rubber system is more obvious. Specifically, the temperature of the pre-reaction 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 thereto; and the reaction time is 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, etc., but not limited thereto.

[0040] In some embodiments of the present application, the antioxidant is a p-phenylenediamine antioxidant, and the active intermediate generated by the pre-reaction has a more significant vulcanization-promoting effect, and is easy to react with the vulcanization system chemicals.

[0041] In some preferred embodiments of the present application, the antioxidant is a compound having a structure of Formula I. The antioxidant having this structure not only has a better vulcanization effect of the vulcanization aid prepared by pre-reaction, but is also more environmentally friendly.

[0042]

[0043] In Formula I, R 1 Selected from C1-C 18 Chain hydrocarbon groups, C3-C18 Alicyclic hydrocarbon or C6-C 18 The aromatic hydrocarbon 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 aliphatic rings separately or simultaneously, R 6 Selected from H, C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w has a value of 1, and at least one of y and z has a value of 1.

[0044] Taking the case where the vulcanization system chemical is 2-thiobenzothiazole as an example, the reaction between the antioxidant having the structure of formula I and the vulcanization system chemical in the pre-reaction is shown in the following reaction equation, and the generated active intermediate has the effect of promoting vulcanization.

[0045]

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

[0047] In some embodiments of the present application, in the pre-reaction, the amount of antioxidant added is 0.5 to 15 parts by weight, the amount of vulcanization 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, and the generated vulcanization aid has a better effect.

[0048] In some embodiments of the present application, the catalyst further comprises zinc oxide, and after the preliminary reaction is completed, the zinc oxide is filtered out. Since zinc oxide is almost insoluble in the second solvent, it can be easily filtered out after the preliminary reaction is completed.

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

[0050] The specific type of carbon black used as filler in the above raw materials can be selected from the prior art. For example, carbon black can be N115 or N220, but is not limited thereto. Fillers are all carbon black, which helps to ensure the wear resistance and cut resistance of the tread rubber. Preferably, the specific surface area of ​​the carbon black is 10 to 500 m 2 / g, more preferably 10 to 300 m 2 / g, more preferably 100 to 300 m 2 / g.

[0051] The rubber in the above raw materials can be selected from the prior art, and there is no particular limitation in this application. In some embodiments of this application, in order to further improve the adaptability of the tire rubber to the use environment of the underground scraper, the above rubber is selected from any one or more of natural rubber, polyisoprene rubber, polystyrene-butadiene rubber, latex 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 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 underground scraper tire can be selected from the prior art, and there is no special limitation in this application, and they will not be described in detail here. For example, the first vulcanizing agent includes sulfur.

[0053] The above raw materials may also include other additives, such as any one or more of oil, antioxidant, coupling agent, activator, antioxidant, heat stabilizer, light stabilizer, flame retardant, dye, pigment, plasticizer, softener, and processing aid. Those skilled in the art can add corresponding additives according to the specific use environment or requirements of the rubber composition and achieve the expected function. This application has no special restrictions on the above other additives. The dosage of other additives is conventional dosage, or adjusted according to the actual requirements.

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

[0055] In some embodiments of the present application, the softener includes any one or more of aromatic oil and tackifying resin, and the amount is 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 the softener in the raw material is not 0, and the addition of the softener to the styrene-butadiene rubber can further improve the processing performance of the rubber.

[0056] In some embodiments of the present 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 gasoline, cycloalkanes and substituted cycloalkanes, and normal alkanes; aromatic hydrocarbon solvents include but are not limited to benzene, toluene, xylene and styrene; chlorinated hydrocarbon solvents include but are not limited to dichloromethane, chloroform, carbon tetrachloride, dichloroethane, chlorobenzene, tetrachloroethylene, and chlorotoluene.

[0057] In some preferred embodiments of the present application, after the rubber is mixed with the first solvent to form a uniform rubber solution, the vulcanization accelerator and the filler are mixed with the rubber solution to make the premix more uniform. In some embodiments of the present application, the concentration of the rubber in the rubber solution is 1% by weight to 60% by weight, preferably 5% by weight to 40% by weight, and more preferably 10% by weight to 30% by weight, which is conducive to improving the uniformity of the premix, saving the amount of solvent as much as possible, and reducing energy consumption.

[0058] In some embodiments of the present application, the method for separating the above-mentioned solvent includes any one or more of atmospheric evaporation, spray drying, expansion drying, low-pressure vacuum drying, flash evaporation, and heating. Specifically, if the method for atmospheric evaporation is used for solvent separation, evaporation can be carried out using an oven or a drying plate. If the method for spray drying is used for solvent separation, the atomization method can be centrifugal atomization, pressure atomization, or two-fluid atomization. If the method for expansion drying is used for solvent separation, heating can be performed first and then the pressure is suddenly released. If the solvent is separated by flash evaporation, it can be at least one of atmospheric flash evaporation or reduced pressure flash evaporation, and the flash evaporation level is 1-3. If the solvent is separated by low-pressure vacuum drying, specifically volatilizing the solvent or suction filtration under vacuum to a pressure lower than one atmosphere, the pressure can be -0.1MPa to 0, preferably -0.09MPa to 0, and more preferably -0.08MPa to 0. The above-mentioned methods for separating the solvent can be used in combination to achieve the purpose of separating the solvent.

[0059] In some embodiments of the present application, the above-mentioned expansion drying is to flash vaporize the solvent through a screw expansion dryer. Preferably, the screw expansion dryer is pushed along the shaft at 0-20MPa, more preferably 1-10MPa, the pitch decreases, friction generates heat, the outlet pressure drops sharply, the rubber strip expands and relaxes, and the solvent in the rubber strip flashes and vaporizes.

[0060] In some embodiments of the present application, after solvent separation, the obtained rubber is dried to obtain a masterbatch; drying after solvent separation is mainly performed to consider the situation where the solvent separation in the rubber is not complete after solvent separation. For example, when the solid content in the rubber after solvent separation is lower than 98wt%, drying is performed, which is beneficial to further improve the performance of the final tire rubber product.

[0061] The drying treatment includes heating drying and / or mechanical drying. Specifically, the heating drying can be drying by oven drying or air drying. Mechanical drying is drying by using an open mill, a kneading mill, an internal mixer, or a screw extruder. The working temperature of the mechanical drying is 20°C-250°C.

[0062] In the above step S2, the masterbatch is subjected to banburying so that the vulcanization accelerator, filler and rubber can be uniformly mixed. Preferably, the banburying temperature is 130-170° C. and the time is 2-8 min, which is conducive to fully exerting the effect of the vulcanization accelerator and further improving the crosslinking density of the rubber.

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

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

[0065] Preferably, the mixing temperature is 130-170° C. Specifically, the mixing temperature may be 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., etc., or other values ​​within the above range. In the final mixing process, adding accelerators and vulcanizing agents helps to avoid scorching of the final mixing rubber.

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

[0067] In some typical embodiments of the present 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 for underground scraper tires.

[0068] According to another typical embodiment of the present application, a rubber for underground scraper tire is provided, and the rubber is prepared by any one of the above-mentioned methods for preparing the rubber for underground scraper tire.

[0069] The rubber for underground scraper tires of the present application uses a vulcanization aid generated by pre-reaction of an antioxidant and a vulcanization system drug during the preparation process. The vulcanization aid contains an active intermediate that promotes vulcanization, which can replace the role of zinc oxide and promote vulcanization to obtain cross-linking density, hardness, tensile stress and hysteresis properties close to those of zinc-containing rubber. The rubber for underground scraper tires prepared by the present application can avoid the use of zinc oxide, achieve zinc-free emissions, and be more environmentally friendly. In addition, the present application uses the above-mentioned continuous method for preparing masterbatch, which not only has a simple and efficient preparation process, but also the prepared rubber has superior processing performance and mechanical properties. The prepared vulcanized rubber has excellent tensile and tear resistance properties, can adapt to harsh working environments, and is particularly suitable for the preparation of underground scraper tires.

[0070] According to another typical embodiment of the present application, a tire for an underground scraper loader is provided, wherein the tire contains the above-mentioned rubber for an underground scraper loader tire.

[0071] Since the above-mentioned rubber for underground scraper loader tires has excellent tensile and tear resistance, can better adapt to the harsh environment underground, and has no zinc emissions and is environmentally friendly, the underground scraper loader tires of the present application also have good performance and are friendly to the use environment, and therefore have good prospects for use and promotion.

[0072] The beneficial effects that can be achieved by the present application will be further illustrated below in combination with embodiments and comparative examples.

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

[0074] Styrene butadiene rubber, ESBR1502, Taiwan Rubber Corporation;

[0075] Carbon black: N234, Shanghai Cabot Co., Ltd.; specific surface area 119m 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 Sinopec Nanjing Chemical Industry Co., Ltd.;

[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] Accelerator DPG, 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 vulcanization aid: 4 parts by weight of zinc oxide, 1 part by weight of stearic acid, 3 parts by weight of environmentally friendly antioxidant 1.2 parts by weight of accelerator CZ is mixed with nonane, pre-reacted at 160°C for 40 minutes, returned to room temperature, filtered to remove zinc, and the filtrate is taken to obtain a zinc-free vulcanization accelerator;

[0086] 2) The zinc-free vulcanizing agent and 60 parts by weight of carbon black N234 were added to a n-hexane solution of 100 parts by weight of ESBR1502, mixed, continuously injected into a reactor, spray dried to separate the solvent, and vacuum dried to obtain a masterbatch A.

[0087] 3) After adding the masterbatch A into an internal mixer and mixing for 1 minute, 1 part by weight of protective wax and 10 parts by weight of tear-resistant resin were added, and after mixing for 3 minutes, the masterbatch was discharged at 150° C. to obtain a first-stage mixed rubber, the Mooney viscosity ML (1+4) @ 125° C. of the mixed rubber was 55.

[0088] 4) After the first rubber mix was left standing for 8 hours, 1.5 parts by weight of accelerator DPG and 1.7 parts by weight of sulfur were added into the internal mixer, mixed for 2 minutes, and discharged at 100° C. to obtain the final rubber mix.

[0089] 5) After the final rubber mix was left for 8 hours, it was vulcanized on a flat vulcanizer at 150° C. for 40 minutes to obtain a continuously prepared 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 vulcanization aid.

[0092] Example 3

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

[0094] Example 4

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

[0096] Comparative Example 1

[0097] In an internal mixer, 60 parts by weight of carbon black N234 were added to 100 parts by weight of ESBR1502 for mixing. After mixing for 1 minute, 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 the mixture was mixed for 3 minutes and discharged at 150°C. After the mixed rubber was allowed 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 internal mixer, and the mixture was mixed for 2 minutes and discharged at 100°C. After the mixed rubber was allowed to stand for 8 hours, it was vulcanized at 150°C for 40 minutes using a flat vulcanizer to obtain a dry vulcanized rubber.

[0098] The vulcanized rubbers prepared in the above examples and comparative examples were tested according to the following method. The test results are listed in Table 1.

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

[0100] Determine the physical properties of the rubber compound (tensile strength, elongation at break) in accordance with GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber;

[0101] Determine the vulcanization characteristics of the rubber compound in accordance with GB / T 16584-1996 Determination of vulcanization characteristics of rubber using a rotorless vulcanizer;

[0102] Determine the hardness of the rubber compound in accordance with GB / T 531.1-2008 Test method for indentation hardness of vulcanized rubber or thermoplastic rubber Part 1: Shore hardness method (Shore hardness)

[0103] The elastic modulus of the rubber 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 were determined using a rotational rheometer.

[0104] Table 1

[0105] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Filler dispersion, grade 8.8 8.9 8.7 7.9 7.1 Hardness, RT, Shore A 63 63 62 65 58 Hardness, 60℃, Shore A 59 58 59 61 54 Tensile strength, MPa 24.3 24.8 23.9 21.8 22.8 Elongation at break, % 634 629 631 588 603 DIN wear index 153 155 152 132 106

[0106] By comparing the physical and dynamic properties of the tread rubber obtained by the continuous preparation process and the dry preparation process in Example 1 and Comparative Example 1, it can be seen that under similar main ingredient formulas, after the continuous preparation process is applied, the dispersion of the filler in the rubber is improved, the tensile properties of the vulcanized rubber are excellent, and the hardness and DIN abrasion are significantly improved.

[0107] Furthermore, the present application obtains performance close to that of a rubber compound with zinc oxide added by adding a vulcanization aid that does not contain zinc element, and the vulcanized rubber A obtained in Examples 1-4 is used for the tread of underground scraper tires. The zinc content in the rubber compound is determined in accordance with "SN / T 2945-2011 Determination of lead, cadmium, chromium, copper, manganese and zinc contents in rubber and its products by inductively coupled plasma atomic emission spectrometry", proving that there is no zinc emission.

[0108] In addition, the tire wear chips of Examples 1-4 were subjected to extraction experiments, and the extracts were subjected to HRMS analysis, which confirmed that the self-synthesized environmentally friendly antioxidants did not produce highly toxic quinone compounds. Toxicity tests on the extracts confirmed that the environmentally friendly antioxidants were less toxic to zebrafish and coho salmon than the commercial antioxidant 4020 (6PPD), etc., and were environmentally friendly.

[0109] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the rubber preparation method uses a vulcanization aid generated by pre-reaction of an antioxidant and a vulcanization system drug. The vulcanization aid contains an active intermediate that promotes vulcanization, which can replace the role of zinc oxide and promote vulcanization to obtain cross-linking density, hardness, tensile stress and hysteresis properties close to those of zinc-containing rubber. The rubber for underground scraper tires prepared by the present application can avoid the use of zinc oxide, achieve zinc-free emissions, and be more environmentally friendly. In addition, the present application uses the above-mentioned continuous method for preparing masterbatch, which not only has a simple and efficient preparation process, but also has excellent processing performance and mechanical properties of the prepared rubber. The prepared vulcanized rubber has excellent tensile and tearing properties, can adapt to harsh working environments, and is particularly suitable for the preparation of underground scraper tires.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing rubber for underground scraper tires, characterized in that: The raw materials of the rubber for underground scraper tires include rubber, filler, vulcanization aid, protective wax, tear-resistant resin, a first accelerator and a first vulcanizing agent; the filler is carbon black, and the vulcanization aid is generated by pre-reaction of an antioxidant and a vulcanization system drug; The method for preparing the rubber for underground scraper tire comprises: Step S1, mixing a vulcanization accelerator, a filler, a rubber and a first solvent to obtain a premix, and continuously introducing the premix into a reactor for solvent separation to obtain a masterbatch; Step S2, after the masterbatch is banburyed, protective wax and tear-resistant resin are added and mixed to obtain a masterbatch; Step S3, mixing the masterbatch with the first accelerator and the first vulcanizing agent, and performing final mixing to obtain a final mixed rubber; Step S4, vulcanizing the final rubber mixture to obtain vulcanized rubber.

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

3. The method for preparing rubber for underground scraper tire according to claim 1, characterized in that: The vulcanization aid is generated by pre-reaction of an antioxidant and a vulcanization system drug under the action of a catalyst, and the catalyst includes stearic acid; 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; Preferably, the pre-reaction temperature is 100-190°C and the time is 1min-120min; More preferably, the pre-reaction temperature is 110-170° C., and the time is 5 min-50 min.

4. The method for preparing rubber for underground scraper tire according to claim 3, characterized in that: The antioxidant is a p-phenylenediamine antioxidant; Preferably, the antioxidant is a compound having a structure of Formula I: In Formula I, R 1 Selected from C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 The aromatic hydrocarbon 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 aliphatic rings separately or simultaneously, R 6 Selected from H, C1-C 18 Chain hydrocarbon groups, C3-C 18 Alicyclic hydrocarbon or C6-C 18 x=0 or 1, y=0 or 1, z=0 or 1, w=0 or 1, and at least one of x and w has a value of 1, and at least one of y and z has a value of 1.

5. The method for preparing rubber for underground scraper tire according to claim 3, characterized in that: The filler is carbon black; The vulcanization system chemicals include a second accelerator; The second accelerator includes any one or more of a sulfonamide accelerator, a sulfenamide accelerator and a thiazole accelerator; Preferably, in the pre-reaction, the antioxidant is added in an amount of 0.5 to 15 parts by weight, the vulcanization system chemical is added in an amount of 0.5 to 15 parts by weight, and the stearic acid is added in an amount of 0.5 to 15 parts by weight.

6. The method for preparing rubber for underground scraper tire according to claim 3, characterized in that: The catalyst also includes zinc oxide. After the preliminary reaction is completed, the zinc oxide is filtered and removed.

7. The method for preparing rubber for underground scraper tire according to claim 1, characterized in that: The solvent separation method includes any one or more of normal pressure evaporation, low pressure vacuum drying, heating, spray drying, expansion drying and flash evaporation; Optionally, after the solvent is separated, the obtained rubber material is dried to obtain the masterbatch, and the drying process includes heating drying and / or mechanical drying.

8. The method for preparing rubber for underground scraper tire according to claim 1, characterized in that: The Mooney viscosity ML (1+4) @ 125°C of the masterbatch is lower than 65. Preferably, the mixing temperature is 130-170°C and the mixing time is 2-8 min. Preferably, the final refining temperature is 80-120°C; The vulcanization temperature of the vulcanization treatment is 140-160° C., and the vulcanization time is 0.4-2 hours.

9. A rubber tire for underground scraper, characterized in that: The rubber is prepared by the method for preparing rubber for underground scraper tires according to any one of claims 1 to 8.

10. A tire for an underground scraper, characterized in that: A rubber for underground scraper tire according to claim 9.

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