Rubber composition, method for continuous preparation of masterbatch using the same and use of the prepared masterbatch

Abstract

The application provides a rubber composition, a method for continuously preparing a master batch by using the rubber composition and application of the prepared master batch. The rubber composition comprises, in parts by weight, 100 parts of rubber, 30-100 parts of a filler, 5-15 parts of a zinc-free vulcanization aid and 5-30 parts of other aids; wherein the zinc-free vulcanization aid is prepared by pre-reaction of an antioxidant and a vulcanization system drug under the action of a catalyst, and the catalyst comprises stearic acid. The rubber composition does not contain zinc elements, can realize zinc-free emission, is friendly to the environment, and the vulcanization aid can make the rubber composition described above obtain a crosslinking density, hardness, modulus and hysteresis and other rubber properties close to those of a zinc-containing rubber composition without containing zinc, and is particularly suitable for preparation of heavy-duty tires, has excellent tensile and tear properties, and can adapt to harsh working environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of tire tread rubber, in particular, relates to a rubber composition, a method for continuously preparing a masterbatch using the same and application of the prepared masterbatch. BACKGROUND

[0002] The working environment of heavy-duty tires is harsh, the driving surface is uneven and has sharp gravel and other debris, is impacted by hard objects, and the thickness of each part of the tire body is large, the heat generated during driving is difficult to dissipate, the temperature rises quickly, and the tire is prone to excessive wear, cuts, punctures, chipping and peeling, and other damage, which seriously affects the service life of the heavy-duty tire. The traditional tire rubber mixing process consumes energy, takes time, and produces a lot of dust pollution, and the filler dispersion is poor. Increasing the amount of filler is a common means to improve the wear resistance of the rubber, and increasing the amount of filler will inevitably increase the energy consumption in the mixing process, the mixing generates a lot of heat, the rubber molecules are subjected to strong shear at high temperature, and are easily plasticized, affecting the tensile, tear and other properties of the rubber; the high-filled rubber usually has high hysteresis loss factor 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 at the same time solve the problem of poor dispersion of high specific surface area fillers in conventional mixing. But most of the wet mixing technology uses latex and filler slurry, and then chemically coagulates to produce masterbatch. CN106750389 A discloses a method for preparing white carbon black / solution polymerized butadiene rubber masterbatch by wet method, uniformly dispersing white carbon black in an organic solvent, adding a silane coupling agent to modify the white carbon black, and then mixing with solution polymerized butadiene rubber latex, removing the organic solvent by water vapor and solvent co-evaporation to obtain white carbon black / solution polymerized butadiene rubber masterbatch. But the dehydration time is long, and it is only applied to white carbon black and solution polymerized butadiene rubber system. The application of carbon black composite material (CEC) is disclosed in "Application of Liquid Phase Mixed NR / Carbon Black Composite Material in Tread Rubber" (Tire Industry, 2005, 25(2):4), which is prepared by a process of mixing natural rubber latex and carbon black water slurry using a liquid phase continuous method. This method of preparing rubber filler masterbatch by liquid phase continuous mixing simplifies the mixing process, reduces the mixing time, and reduces energy consumption and labor, but the variety and content of rubber and filler used in the preparation of the masterbatch are limited, and the masterbatch additives still need to be added during the mixing of the tread rubber.

[0004] On the other hand, zinc oxide in tire wear debris enters the water circulation system, which 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 suggest limiting the use of zinc or zinc oxide in tires. Enterprises in the rubber tire field are facing pressure to green transform and strive to reduce the environmental impact of the production process. SUMMARY

[0005] The main purpose of the present application is to provide a rubber composition, a method for continuously preparing a master batch using the same, and the application of the prepared master batch, so as to solve the problem of environmental pollution caused by the presence of zinc in heavy-duty tires in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a rubber composition is provided, which comprises, in parts by weight: 100 parts of rubber, 30-100 parts of filler, 5-15 parts of zinc-free curing aid, and 5-30 parts of other auxiliary agents; wherein the zinc-free curing aid is prepared by pre-reaction of an antioxidant and a vulcanization system drug under the action of a catalyst, and the catalyst comprises stearic acid.

[0007] Further, the reaction temperature of the pre-reaction is 100-190 °C, and the reaction time is 1 min-120 min; preferably, the reaction temperature is 110-170 °C, and the reaction time is 5 min-50 min.

[0008] Preferably, 0.5-15 phr of stearic acid, 0.5-15 phr of antioxidant, and 0.5-15 phr of vulcanization system drug are added in the pre-reaction.

[0009] Preferably, a first solvent is further added in the pre-reaction, and the first solvent is any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene, and xylene.

[0010] Optionally, the catalyst further comprises 1-10 phr of zinc oxide, and the zinc oxide is filtered out after the pre-reaction is completed.

[0011] Further, the vulcanization system drug comprises any one or more of a vulcanizing agent and an accelerator, the accelerator comprises any one or more of a sulfonamide vulcanization accelerator, a sulfenamide vulcanization accelerator, and a thiazole vulcanization accelerator, and preferably, the accelerator is selected from any one or more of CZ, DZ, DM, M, and NS.

[0012] And / or, the antioxidant is a p-phenylenediamine antioxidant,

[0013] Preferably, the antioxidant is selected from any one or more of 4020 (6PPD), 4010NA (IPPD), and 7PPD.

[0014] Preferably, the anti-aging agent is a compound having the structure of Formula I:

[0015] Formula I

[0016] In Formula I, R 1 is a chain hydrocarbon group selected from C1-C 18 , a cycloaliphatic group selected from C3-C 18 , or an aromatic group selected from C6-C 18 ; R 2 , R 3 , R 4 , R 5 are independently selected from H, a chain hydrocarbon group selected from C1-C 18 , a cycloaliphatic group selected from C3-C 2 , or an aromatic group selected from C6-C 3 ; or R 4 and R 5 may also form a cycloaliphatic ring, respectively or simultaneously; R 6 is selected from H, a chain hydrocarbon group selected from C1-C 18 , a cycloaliphatic group selected from C3-C 18 , or an aromatic group selected from 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 is 1, and at least one of y and z is 1.

[0017] Further, the filler is selected from any one or more of carbon black and white carbon black;

[0018] Preferably, the white carbon black has a specific surface area of 10-500 m 2 / g, more preferably 10-300 m 2 / g, and further more preferably 100-300 m 2 / g.

[0019] Preferably, the white carbon black has an oil absorption value of 20-350 mL / 100g, more preferably 25-300 mL / 100g, and further more preferably 30-290 mL / 100g.

[0020] Preferably, the carbon black has a specific surface area of 10-500 m 2 / g, more preferably 10-300 m 2 / g, and further more preferably 100-300 m 2 / g.

[0021] Further, the rubber is selected from any one or more of natural rubber, polyisoprene rubber, solution-polymerized styrene-butadiene rubber, emulsion-polymerized styrene-butadiene rubber, and polybutadiene rubber;

[0022] Preferably, the molecular weight of the rubber is 10 million to 40 million, more preferably 50 million to 30 million, and even more preferably 10 million to 8 million.

[0023] Furthermore, other additives include any one or more of the following: oils, antioxidants, coupling agents, activators, antioxidants, heat stabilizers, light stabilizers, flame retardants, dyes, pigments, plasticizers, softeners, processing aids, vulcanizing agents, and accelerators;

[0024] Preferably, the coupling agent includes any one or more of bis(triethoxypropylsilane)tetrasulfide and disulfide, 3-thiocyanopropyl-triethoxysilane, γ-mercaptopropyl-trimethoxysilane, zirconate coupling agents, phthalate coupling agents and nitro coupling agents;

[0025] Preferably, the softener includes any one or more of aromatic oils, tackifying resins, and tear-resistant resins.

[0026] To achieve the above objectives, according to one aspect of the present invention, a method for continuously preparing masterbatch using any of the above-mentioned rubber compositions is provided, the method comprising: step S1, mixing filler, zinc-free vulcanizing agent, other additives, rubber and a second solvent, and forming a mixture by stirring; step S2, solvent separation of the mixture to obtain masterbatch.

[0027] Furthermore, solvent separation includes any one of the following: solvent separation by evaporation, solvent separation by low-pressure vacuum drying, solvent separation by heating, solvent separation by spray drying, solvent separation by expansion drying, and solvent separation by flash evaporation;

[0028] Preferably, after step S2, step S3 is further included, in which the masterbatch is dried by heat drying and / or mechanical drying.

[0029] Furthermore, the second 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;

[0030] Preferably, step S1 includes mixing the rubber and the second solvent to form a rubber solution, and then mixing it with filler, zinc-free vulcanizing agent, and other additives;

[0031] Preferably, the concentration of rubber in the rubber solution is 1% to 60% by weight, more preferably 5% to 40% by weight, and even more preferably 10% to 30% by weight.

[0032] According to another aspect of the present invention, the application of masterbatch prepared by any of the above methods in heavy-duty tires is provided.

[0033] By applying the technical solution of this invention, the above-mentioned rubber composition employs a zinc-free vulcanizing aid. This zinc-free vulcanizing aid, under the catalysis of stearic acid, reacts the antioxidant and the vulcanizing system chemicals to generate an active intermediate. This active intermediate promotes vulcanization and can pre-activate the accelerator, allowing it to replace the function of zinc oxide. This rubber composition contains no zinc, achieving zinc-free emissions and being environmentally friendly. Furthermore, this vulcanizing aid enables the above-mentioned rubber composition to achieve crosslinking density, hardness, tensile stress, and hysteresis properties close to those of zinc-containing rubber compositions, even without zinc. It is particularly suitable for the preparation of heavy-duty tires, exhibiting excellent tensile and tear properties, and can withstand harsh working environments. Detailed Implementation

[0034] 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.

[0035] As analyzed in the background section of this application, heavy-duty tires operate in harsh environments, placing higher demands on rubber compounds than ordinary tires. Furthermore, existing heavy-duty tires contain zinc, which poses an environmental pollution problem. Based on this, this application provides a rubber composition, a method for continuously preparing masterbatch using the composition, and applications of the prepared masterbatch.

[0036] According to a typical embodiment of this application, a rubber composition is provided, characterized in that, by weight, the rubber composition comprises: 100 parts rubber, 30-100 parts filler, 5-15 parts zinc-free vulcanizing auxiliaries, and 5-30 parts other auxiliaries; wherein, the zinc-free vulcanizing auxiliaries are prepared by pre-reaction of an antioxidant and a vulcanizing system reagent under the action of a catalyst, the catalyst including stearic acid.

[0037] The aforementioned rubber composition employs a zinc-free vulcanizing aid. This aid, catalyzed by stearic acid, reacts the antioxidant and vulcanizing agents to generate an active intermediate. This active intermediate promotes vulcanization, acting as an early activation accelerator and thus replacing the role of zinc oxide. The rubber composition contains no zinc, achieving zero zinc emissions and being environmentally friendly. Furthermore, this vulcanizing aid enables the rubber composition to achieve crosslinking density, hardness, tensile stress, and hysteresis properties close to those of zinc-containing rubber compositions, even without zinc. It is particularly suitable for the manufacture of heavy-duty tires, exhibiting excellent tensile and tear properties, and capable of withstanding harsh working environments.

[0038] Taking phenylenediamine antioxidants and 2-thiobenzothiazole sulfurization system pharmaceuticals as an example, the reaction that occurs in the pre-reaction is shown in the following reaction equation, and the generated active intermediate has the effect of promoting sulfurization.

[0039]

[0040] To further increase the content of active intermediates in the zinc-free vulcanizing aid, in some embodiments of this application, the reaction temperature of the above-mentioned pre-reaction is 100-190 °C and the reaction time is 1 min-120 min; the preferred reaction temperature is 110-170 °C and the reaction time is 5 min-50 min. The obtained zinc-free vulcanizing aid has a better effect on promoting crosslinking, and the tires prepared by the rubber composition containing it have better overall performance.

[0041] In some preferred embodiments of this application, the addition of 0.5-15 phr of stearic acid, 0.5-15 phr of antioxidant, and 0.5-15 phr of vulcanization system chemicals during the pre-reaction process results in higher reaction efficiency and facilitates the synergistic effect of the zinc-free vulcanization auxiliaries formed by the above components in the rubber composition.

[0042] In some embodiments of this application, a first solvent is added to the pre-reaction process to ensure uniform dispersion of the antioxidant, vulcanization system reagents, and catalyst, further improving the activation effect of the prepared zinc-free vulcanization aid. The first solvent in the pre-reaction process only needs to be able to dissolve the stearic acid, antioxidant, and vulcanization system reagents participating in the pre-reaction, and should not adversely affect the reaction of the antioxidant and vulcanization system reagents; this can be selected from existing technologies. The amount of solvent added can be adjusted according to its solubility in the aforementioned pre-reaction raw materials.

[0043] Preferably, the first solvent is any one or more of butanol, octanol, N-methylpyrrolidone, octane, nonane, decane, toluene, and xylene. These solvents not only have good solubility for stearic acid, antioxidants, and sulfurized system chemicals, but also facilitate the pre-reaction and improve reaction efficiency.

[0044] The first solvent added in the pre-reaction can be removed after the reaction is complete, or the product system containing the solvent, i.e., the zinc-free vulcanizing agent solution, can be used as part of the rubber composition and directly mixed with the rubber solution in the subsequent continuous preparation of masterbatch.

[0045] In some embodiments of this application, the catalyst further includes 1-10 phr of zinc oxide. After the pre-reaction is completed, the zinc oxide is filtered out. Through the co-catalysis of zinc oxide and stearic acid, more active intermediates can be generated in the pre-reaction, resulting in the rubber composition having better performance. Furthermore, since the zinc oxide is still not solid in the first solvent, by filtering out the zinc oxide in the pre-reaction solution system, the rubber composition can also be made zinc-free and have high performance.

[0046] In some embodiments of this application, the vulcanization system comprises one or more of vulcanizing agents and accelerators. Preferably, the vulcanization system contains an accelerator, and the vulcanizing agent is added during the preparation of the rubber product. The accelerator comprises one or more of sulfonamide vulcanization accelerators, sulfenamide vulcanization accelerators, and thiazole vulcanization accelerators. Preferably, the accelerator is selected from one or more of CZ, DZ, DM, M, and NS.

[0047] In some embodiments of this application, the antioxidant is a p-phenylenediamine antioxidant, such as any one or more of 4020 (6PPD), 4010NA (IPPD), and 7PPD.

[0048] In some preferred embodiments of this application, the antioxidant is a compound having the structure of Formula I:

[0049] Formula I

[0050] 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.

[0051] When the antioxidant added in the above pre-reaction is a p-phenylenediamine antioxidant with the structure of Formula I, it not only has a better effect, but is also more environmentally friendly.

[0052] In some embodiments of this application, the aforementioned zinc-free vulcanizing aid can also be a masterbatch-type vulcanizing aid, i.e., the pre-reaction product is mixed with rubber. Preferably, the amount of rubber added is 0-150 phr. In the preparation process of this masterbatch-type zinc-free vulcanizing aid, if the aforementioned first solvent is added in the pre-reaction, the first solvent in the pre-reaction system can be removed before mixing with the rubber, or it can be directly mixed with the rubber. After mixing, the solvent can be removed, or it can be used directly in subsequent processes without removing the solvent.

[0053] The rubber included in the above-mentioned zinc-free vulcanizing auxiliaries can be any one or more of natural polymers or synthetic polymers. Preferably, the rubber is selected from any one or more of natural rubber, styrene-butadiene rubber, isoprene rubber, natural eucommia gum, polyisoprene rubber, butadiene rubber, halogenated butyl rubber, and ethylene propylene diene monomer (EPDM) rubber. Preferably, the molecular weight of the rubber is 10 million to 40 million, more preferably 50 million to 30 million, and even more preferably 10 million to 8 million.

[0054] It should be noted that when the zinc-free vulcanizing aid is a masterbatch type aid, the 100 parts of rubber contained in the above rubber composition, and the 5 to 15 parts of zinc-free vulcanizing aid on this basis, wherein the 5 to 15 parts of zinc-free vulcanizing aid are the number of parts of the other components in the masterbatch type aid besides rubber, and the rubber in the masterbatch type aid is counted within the 100 parts of rubber.

[0055] In some typical embodiments of this application, in order to further improve the performance of the rubber composition and enable the prepared tires to better adapt to harsh working environments, the rubber in the rubber composition 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 40,000,000, more preferably 5,000 to 30,000,000, and even more preferably 10,000 to 8,000,000.

[0056] In some embodiments of this application, the filler is selected from any one or more of carbon black and silica. Preferably, the specific surface area of ​​the silica is 10~500m². 2 / g, more preferably 10~300 m 2 / g, more preferably 100~300m 2 / g; preferably, the oil absorption value of silica is 20~350 mL / 100g, more preferably 25~300 mL / 100g, and even more preferably 30~290 mL / 100g; wherein, based on 100 parts by weight of rubber, the amount of silica is 0 to 100 parts by weight, preferably 0 to 70 parts by weight. Preferably, the specific surface area of ​​the carbon black is 10~500 m² / g. 2 / g, more preferably 10~300 m 2 / g, further preferably 100~300 m 2 / g. Based on 100 parts by weight of rubber, the amount of carbon black is 0 to 100 parts by weight, preferably 0 to 70 parts by weight.

[0057] Other additives in the above-mentioned rubber composition include, but are not limited to, any one or more of oils, antioxidants, coupling agents, activators, antioxidants, heat stabilizers, light stabilizers, flame retardants, dyes, pigments, plasticizers, softeners, processing aids, vulcanizing agents, and accelerators. Those skilled in the art can add appropriate additives to achieve the desired function according to the specific application environment or requirements of the rubber composition. This application does not impose any particular limitations on the above-mentioned other additives. The dosage of other additives is the conventional dosage, or may be adjusted according to actual requirements.

[0058] 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.

[0059] In some embodiments of this application, the softener includes any one or more of aromatic oils, tackifying resins, and tear-resistant resins, and is used in an amount of 0 to 20 parts by weight, preferably 0 to 10 parts by weight.

[0060] According to another typical embodiment of this application, a method for continuously preparing masterbatch using any of the above-mentioned rubber compositions is provided. The method includes: step S1, mixing filler, zinc-free vulcanizing agent, other additives, rubber and a second solvent, and forming a mixture by stirring; step S2, separating the solvent from the mixture to obtain masterbatch.

[0061] The continuous method for preparing masterbatch described above is not only simple, continuous, and efficient, but also produces masterbatch with superior processing and mechanical properties. Furthermore, because this method uses the aforementioned rubber composition as raw material and employs a zinc-free vulcanizing agent, it achieves zero zinc emissions, making it environmentally friendly. Moreover, this vulcanizing agent enables the aforementioned rubber composition to achieve crosslinking density, hardness, tensile stress, and hysteresis properties close to those of zinc-containing rubber compositions, even without zinc. The masterbatch prepared by this method exhibits excellent tensile and tear properties, making it suitable for harsh working environments and particularly well-suited for the manufacture of heavy-duty tires.

[0062] The second solvent can be selected from existing technologies and can be a benign solvent for rubber. For example, the second solvent can be selected from any one or more of aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, chlorinated hydrocarbon solvents, ketone solvents, ether solvents, and ester solvents. Among these, 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.

[0063] In some preferred embodiments of this application, step S1 includes mixing rubber and a second solvent to form a rubber solution, and then mixing it with filler, zinc-free vulcanizing agent, and other additives. Dissolving the rubber in the solvent first allows for more uniform mixing of the rubber and other components. Preferably, the concentration of rubber in the rubber solution is 1% to 60% by weight, more preferably 5% to 40% by weight, and even more preferably 10% to 30% by weight. This is beneficial for improving the preparation efficiency and product performance of the masterbatch and reducing energy consumption.

[0064] The mixture obtained in step S1 can proceed to the next step immediately, or it can be left to stand for a certain period of time, and then heated or not heated. When heated, the temperature is between 10°C and 200°C. When the above heating temperature is higher than the boiling point of the solvent, the heating must be carried out in a pressure vessel.

[0065] The solvent separation methods described above can be selected from existing technologies. In some embodiments of this application, solvent separation includes any one of the following: solvent separation by evaporation, solvent separation by low-pressure vacuum drying, solvent separation by heating, solvent separation by spray drying, solvent separation by expansion drying, and solvent separation by flash evaporation. Specific process parameters for solvent separation using the above methods can be referred to existing technologies, and this application does not impose any particular limitations.

[0066] In some embodiments of this application, solvent separation is performed by evaporation, using an oven or drying plate. In some embodiments of this application, solvent separation is performed by spray drying, using centrifugal atomization, pressure atomization, or two-fluid atomization. In some embodiments of this application, solvent separation is performed by expansion drying, wherein the expansion drying method involves heating followed by a sudden release of pressure. In some embodiments of this application, solvent separation is performed by flash evaporation, which can be at least one of atmospheric pressure flash evaporation or reduced pressure flash evaporation, with 1-3 flash stages. In some embodiments of this application, solvent separation is performed by low-pressure vacuum drying, specifically by evaporating the solvent or filtering it 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. 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.

[0067] In some embodiments of this application, in order to further remove solvents or moisture from the rubber compound, when the solid content in the rubber compound is less than 98 wt%, after step S2, step S3 is further included, in which the masterbatch is dried by heating and / or mechanical drying.

[0068] In some embodiments of this application, the above-mentioned heating and drying is oven drying or air drying.

[0069] In some embodiments of this application, mechanical drying is performed using an open mill, kneader, internal mixer, or screw extruder, and the operating temperature of mechanical drying is 20℃-250℃.

[0070] In step S3, heating drying can be performed first, followed by mechanical drying, or mechanical drying can be performed first, followed by heating drying. When mechanical drying is selected, heating drying can be performed simultaneously at a temperature of 10°C to 250°C; when heating drying is selected, heating can be carried out in a gaseous medium, which includes at least one of air, nitrogen, water vapor, and CO2.

[0071] In the solvent separation process described in steps S2 and / or S3, the solvent can be recovered and recycled. The recovery method can be selected from existing technologies, such as recovery through a condenser and a fractionation tower. The solvent recovery method can use any method known in the art, such as recovering the vaporized solvent through surface condensation or direct contact condensation. When using the direct contact condensation method, water can be used as the coolant.

[0072] The masterbatch prepared in step S2 above can be further compounded with other additives, such as oil, antioxidants, protective waxes, and sulfur. After vulcanization, vulcanized rubber can be prepared for use in the manufacture of heavy-duty tires. According to another typical embodiment of this application, an application of the masterbatch prepared by any of the above methods in heavy-duty tires is provided. Applying the above masterbatch to heavy-duty tires not only allows them to adapt well to harsh working environments but also achieves zinc-free emissions, making them environmentally friendly.

[0073] The beneficial effects that this application can achieve will be further illustrated below with reference to embodiments and comparative examples.

[0074] The specific sources of the materials used in the embodiments and comparative examples of this application are as follows:

[0075] Styrene-butadiene rubber, ESBR1502, TSRC Corporation;

[0076] Natural rubber (NR), STR20#, standard rubber;

[0077] Carbon black: N115, Shanghai Cabot Co., Ltd.; specific surface area 137 m² 2 / g, oil absorption value 113mL / 100g;

[0078] Carbon black: N220, Shanghai Cabot Co., Ltd.; specific surface area 114 m² 2 / g, oil absorption value 114mL / 100g;

[0079] Carbon black: N330, Shanghai Cabot Co., Ltd.; specific surface area 78 m² 2 / g, oil absorption value 102mL / 100g;

[0080] Silica: 165MP, manufactured by Quecheng Silicon Chemical Co., Ltd.; specific surface area 179m² 2 / g, oil absorption value 245mL / 100g;

[0081] Silica: 115MP, manufactured by Quecheng Silicon Chemical Co., Ltd.; specific surface area 125m³ 2 / g, oil absorption value 250mL / 100g;

[0082] Stearic acid, a product of Tyco Brown Chemical (Zhangjiagang) Co., Ltd.

[0083] Protective wax, a product of Qingdao Jinxian Chemical Co., Ltd.

[0084] Antioxidant RD, a product of Nanjing Chemical Industry Co., Ltd., China Petrochemical Corporation;

[0085] Antioxidant 4020, a product of Jiangsu Shengao Chemical Technology Co., Ltd.

[0086] Accelerator CZ, a product of Shandong Shangshun Chemical Co., Ltd.

[0087] Accelerator DZ, a product of Shandong Shangshun Chemical Co., Ltd.

[0088] Accelerator DM, a product of Shandong Shangshun Chemical Co., Ltd.

[0089] Accelerator M is a product of Shandong Shangshun Chemical Co., Ltd.

[0090] Accelerator NS, a product of Shandong Shangshun Chemical Co., Ltd.

[0091] Sulfur, a product of Liaoning Chaoyang Tianming Industry and Trade Co., Ltd.

[0092] Silane coupling agent, Si69, Nanjing Shuguang Silane Chemical Co., Ltd.;

[0093] Comparative Example 1-1

[0094] In a mixer, 40 parts of carbon black N220, 20 parts of silica 165MP, and 2 parts of Si69 are added to 80 parts of natural rubber and 20 parts of styrene-butadiene rubber for mixing. After mixing for a period of time, 4 parts of aromatic oil, 4 parts of zinc oxide, 2 parts of stearic acid, 2 parts of antioxidant 4020, 1 part of antioxidant RD, and 1 part of protective wax are added. After the mixed rubber is left to stand for 8 hours, 1 part of accelerator CZ and 1.2 parts of sulfur are added to the mixer. After the mixed rubber is left to stand for 8 hours, it is vulcanized at 150°C for 40 minutes using a flat vulcanizing machine to obtain dry vulcanized rubber a.

[0095] Comparative Examples 1-2

[0096] 40 parts of carbon black N220, 20 parts of silica 165MP, and 2 parts of Si69 were added to a hexane solution of 80 parts of natural rubber and 20 parts of styrene-butadiene rubber. After mixing, the mixture was continuously injected into a reactor to separate the solvent and dried to obtain masterbatch A. Masterbatch A was added to a mixer and homogenized. Then, 4 parts of aromatic oil, 4 parts of zinc oxide, 2 parts of stearic acid, 2 parts of antioxidant 4020, 1 part of antioxidant RD, and 1 part of protective wax were added. After the mixture was left to stand for 8 hours, 1 part of accelerator CZ and 1.2 parts of sulfur were added to the mixer. 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 continuously prepared vulcanized rubber aa.

[0097] Example 1

[0098] Preparation of zinc-free vulcanizing aids:

[0099] 10 phr stearic acid, 12.5 phr antioxidant 4020, and 11.5 phr vulcanization accelerator CZ were mixed in xylene and pre-reacted at 130 °C for 40 min to obtain a zinc-free vulcanization aid.

[0100] Take 1 / 10 of the above-mentioned zinc-free vulcanizing auxiliaries, 40 parts of carbon black N220, 20 parts of silica 165MP, and 2 parts of Si69, and add them to a hexane solution of 80 parts of natural rubber and 20 parts of styrene-butadiene rubber. After mixing, continuously inject the mixture into a reactor to separate the solvent and dry it to obtain masterbatch A. Add masterbatch A to a mixer and mix it evenly. Then add 4 parts of aromatic oil, 1 part of antioxidant RD, and 1 part of protective wax. After the compound has been left to stand for 8 hours, add 1.2 parts of sulfur to the mixer. After the compound has been left to stand for 8 hours, vulcanize it in a flat vulcanizing machine at 150°C for 40 minutes to obtain continuously prepared vulcanized rubber A.

[0101] 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.

[0102] 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".

[0103] 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.

[0104] 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)

[0105] The dynamic properties of rubber compounds were determined using a rotational rheometer in accordance with GB / T 9870.1-2006 Determination of dynamic properties of vulcanized rubber or thermoplastic rubber - Part 1: General rules.

[0106] 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.

[0107] Table 1

[0108]

[0109] A comparison of the physical and dynamic properties of the tread compounds obtained using continuous and dry preparation processes in Examples 1 and Comparative Examples 1-1 and 1-2 shows that, under the same formulation, the continuous preparation process improves the dispersion of fillers in the rubber, resulting in excellent tensile properties of the vulcanizate, reduced high-temperature heat generation, and significantly improved DIN abrasion. Furthermore, this application achieved properties similar to those obtained with zinc oxide by adding a zinc-free vulcanization aid. The vulcanizate A obtained in Example 1 was used for the tread of a heavy-duty tire. The zinc content in the compound was determined according to the standard SN / T 2945-2011 "Determination of Lead, Cadmium, Chromium, Copper, Manganese and Zinc Content in Rubber and its Products - Inductively Coupled Plasma Atomic Emission Spectrometry," proving that there was no zinc emission.

[0110] Examples 2-5

[0111] The difference from Example 1 is that the zinc-free vulcanizing aid uses a different antioxidant, and the rubber and filler components in the continuous preparation process are different, as detailed in Table 2 for the rubber compound formulation. Otherwise, the preparation methods of the zinc-free vulcanizing aid and the vulcanized rubber are the same as in Example 1.

[0112] Comparative Examples 2-5

[0113] Furthermore, Comparative Examples 2 to 5 were established based on the same rubber compound formulation as those used in the continuous vulcanization process, and their specific formulations are shown in Table 3 below. The preparation process of the dry vulcanized rubbers in Comparative Examples 2 to 5 was the same as that in Comparative Example 1-1.

[0114] Table 2

[0115]

[0116] Table 3

[0117]

[0118] Antioxidants used in Tables 2 and 3 , , and It was prepared in-house.

[0119] The above embodiments and comparative examples were tested using the same method as in Embodiment 1. The test results are shown in Tables 4 and 5 below.

[0120] Table 4

[0121]

[0122] Table 5

[0123]

[0124] As can be seen from the test results in Tables 4 and 5, under the same formulation, the application of the continuous preparation process improves the dispersion of fillers in rubber, results in excellent tensile properties of the vulcanizate, and reduces high-temperature heat generation.

[0125] The vulcanized rubber obtained in Examples 2-5 was used in the preparation of heavy-duty tires, such as giant tires, engineering tires, mining truck tires, all-steel mining tires, and all-terrain crane tires. Tests showed no zinc emissions.

[0126] In addition, extraction experiments were conducted on the tire wear debris from Examples 2-5, 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 the commercial antioxidant 4020 (6PPD), making it environmentally friendly.

[0127] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: The rubber composition uses a zinc-free vulcanizing aid. This zinc-free vulcanizing aid, under the catalysis of stearic acid, allows the antioxidant and the vulcanizing system chemicals to react, generating an active intermediate. This active intermediate promotes vulcanization, acting as an early activation accelerator, allowing it to replace the role of zinc oxide. The rubber composition does not contain zinc, achieving zinc-free emissions and being environmentally friendly. Furthermore, this vulcanizing aid enables the rubber composition to achieve crosslinking density, hardness, tensile stress, and hysteresis properties close to those of zinc-containing rubber compositions, even without zinc. It is particularly suitable for the preparation of heavy-duty tires, exhibiting excellent tensile and tear properties, and can withstand harsh working environments.

[0128] 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 rubber composition, characterized in that, By weight, the rubber composition comprises: 100 parts rubber, 30-100 parts filler, 5-15 parts zinc-free vulcanizing agent, and 5-30 parts other additives; wherein, The zinc-free vulcanization aid is prepared by pre-reaction of an antioxidant and a vulcanization system reagent under the action of a catalyst, wherein the catalyst includes stearic acid. The pre-reaction process includes the addition of 0.5-15 phr of stearic acid, 0.5-15 phr of antioxidant, and 0.5-15 phr of vulcanization system chemicals. The reaction temperature of the pre-reaction is 100-190℃, and the reaction time is 1 min-120 min; The antioxidant is a p-phenylenediamine antioxidant, and the vulcanization system includes an accelerator, which is selected from any one or more of CZ, DZ, DM, M and NS.

2. The rubber composition according to claim 1, characterized in that, The pre-reaction temperature is 110-170°C, and the reaction time is 5 min-50 min.

3. The rubber composition according to claim 1, characterized in that, The pre-reaction also includes the addition of a first solvent, which is any one or more of butanol, octanol, N-methylpyrrolidone, octane, nonane, decane, toluene, and xylene.

4. The rubber composition according to claim 1, characterized in that, The catalyst also includes 1-10 phr of zinc oxide, and after the pre-reaction is completed, the zinc oxide is filtered out.

5. The rubber composition according to claim 1, characterized in that, The antioxidant is selected from any one or more of 4020, 4010NA and 7PPD.

6. The rubber composition 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.

7. The rubber composition according to claim 1, characterized in that, The filler is selected from any one or more of carbon black and silica.

8. The rubber composition according to claim 7, characterized in that, The specific surface area of ​​the silica is 10~500m². 2 / g.

9. The rubber composition according to claim 7, characterized in that, The specific surface area of ​​the silica is 10~300m². 2 / g.

10. The rubber composition according to claim 7, characterized in that, The specific surface area of ​​the silica is 100~300m². 2 / g.

11. The rubber composition according to claim 7, characterized in that, The oil absorption value of the silica is 20~350mL / 100g.

12. The rubber composition according to claim 7, characterized in that, The oil absorption value of the silica is 25~300mL / 100g.

13. The rubber composition according to claim 7, characterized in that, The oil absorption value of the silica is 30~290mL / 100g.

14. The rubber composition according to claim 7, characterized in that, The specific surface area of ​​carbon black is 10~500m². 2 / g.

15. The rubber composition according to claim 7, characterized in that, The specific surface area of ​​carbon black is 10~300 m². 2 / g.

16. The rubber composition according to claim 7, characterized in that, The specific surface area of ​​carbon black is 100~300 m². 2 / g.

17. The rubber composition according to claim 1, characterized in that, 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.

18. The rubber composition according to claim 17, characterized in that, The molecular weight of the rubber is between 1,000 and 40,000,000.

19. The rubber composition according to claim 17, characterized in that, The molecular weight of the rubber is between 5,000 and 30,000,000.

20. The rubber composition according to claim 17, characterized in that, The molecular weight of the rubber is between 10,000 and 8 million.

21. The rubber composition according to claim 1, characterized in that, The other additives include any one or more of the following: oils, antioxidants, coupling agents, activators, antioxidants, heat stabilizers, light stabilizers, flame retardants, dyes, pigments, plasticizers, softeners, processing aids, vulcanizing agents, and accelerators.

22. The rubber composition according to claim 21, characterized in that, The coupling agent includes any one or more of bis(triethoxypropylsilane)tetrasulfide and disulfide, 3-thiocyanopropyl-triethoxysilane, γ-mercaptopropyl-trimethoxysilane, zirconate coupling agents, phthalate coupling agents, and nitro coupling agents.

23. The rubber composition according to claim 21, characterized in that, The softener includes any one or more of aromatic oils, tackifying resins, and tear-resistant resins.

24. A method for continuously preparing masterbatch using the rubber composition according to any one of claims 1 to 23, characterized in that, The method includes: Step S1: Mix the filler, zinc-free vulcanizing agent, other additives, rubber, and second solvent, and stir to form a mixture; Step S2: Solvent separation is performed on the mixture to obtain masterbatch.

25. The method according to claim 24, characterized in that, The solvent separation includes any one of the following: solvent separation by evaporation, solvent separation by low-pressure vacuum drying, solvent separation by heating, solvent separation by spray drying, solvent separation by expansion drying, and solvent separation by flash evaporation.

26. The method according to claim 24, characterized in that, After step S2, step S3 is also included, in which the masterbatch is dried by heat drying and / or mechanical drying.

27. The method according to any one of claims 24 to 26, characterized in that, The second 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.

28. The method according to claim 24, characterized in that, Step S1 includes mixing the rubber and the second solvent to form a rubber solution, and then mixing it with the filler, the zinc-free vulcanizing agent, and other additives.

29. The method according to claim 28, characterized in that, The rubber concentration in the rubber solution is 1% to 60% by weight.

30. The method according to claim 28, characterized in that, The rubber concentration in the rubber solution is 5% to 40% by weight.

31. The method according to claim 28, characterized in that, The rubber concentration in the rubber solution is 10% to 30% by weight.

32. The use of the masterbatch prepared by any one of claims 24 to 31 in heavy-duty tires.

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