Continuous masterbatch preparation method, rubber article, and off-the-road tire

Abstract

The application provides a continuous masterbatch preparation method, a rubber product and an off-road tire. The preparation method comprises the following steps: S1, mixing an antioxidant, a vulcanization system medicine and a catalyst to perform pre-reaction to obtain a vulcanization aid, the pre-reaction temperature is 100-190 DEG C, and the reaction time is 1 min-120 min; S2, mixing and stirring a mixing raw material and a first solvent to obtain a premix, the mixing raw material comprises rubber, the vulcanization aid, white carbon black and a silane coupling agent; S3, performing solvent separation on the premix to obtain a masterbatch; and S4, mixing and vulcanizing the masterbatch with other aids to obtain a vulcanized rubber, the other aids comprise an accelerator and sulfur. The rubber prepared by the above method not only has good rubber performance, but also realizes zinc-free emission, is friendly to the environment, and can well meet the demand of the off-road tire for performance and environmental adaptability and friendliness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tread rubber, in particular to a continuous masterbatch preparation method, a rubber product and an off-road tire. BACKGROUND

[0002] Off-road tires are usually used in muddy, sandy or rugged mountain roads, etc. The tires are prone to scratches, chunks, punctures, and poor wear resistance, and have a relatively low service life.

[0003] CN104530498 A discloses an off-road all-steel radial tire tread rubber and a preparation method thereof, which uses 100 parts of natural rubber, 30-50 parts of carbon black (N115), 7-18 parts of white carbon black, 1-4 parts of silane coupling agent, etc. In order to ensure the dispersion of carbon black and white carbon black, the mixing is divided into four stages. First, carbon black masterbatch is prepared, then part of the required raw materials is mixed, and then returned to the mixer for mixing, and finally the other raw materials are added to prepare the final rubber compound. This mixing method has many stages, consumes a lot of energy, and the dispersion of fillers with high specific surface area is poor, which can affect the performance of the rubber compound. Therefore, the properties of the rubber compound such as puncture resistance, low heat build-up, and wear resistance are mutually restricted, and the conventional dry mixing method cannot meet all the requirements.

[0004] In recent decades, people have tried to directly mix latex and filler slurry, and then perform chemical coagulation to produce masterbatch. CN106750389 A discloses a method for preparing white carbon black / solution polymerized butadiene rubber masterbatch by wet method. First, the white carbon black is uniformly dispersed in an organic solvent, and then the white carbon black is modified by adding a silane coupling agent. Then, the modified white carbon black is mixed with a solution polymerized butadiene rubber solution, and the organic solvent is removed by water vapor and solvent co-evaporation to obtain a white carbon black / solution polymerized butadiene rubber masterbatch. However, the dehydration time is relatively long, and this method is only applicable to white carbon black and solution polymerized butadiene rubber systems. The application of carbon black composite material (CEC) is disclosed in "Application of Liquid Mixed NR / Carbon Black Composite Material in Tread Rubber" (Tire Industry, 2005, 25(2):4). The carbon black composite material is prepared by mixing natural rubber latex and carbon black water slurry using a liquid phase continuous process developed by Cabot Corporation. This method simplifies the mixing process, reduces the mixing time, and reduces energy consumption and labor. However, the types and amounts of rubber and fillers used in the preparation of the masterbatch are limited, and the additives for the masterbatch still need to be added during the mixing process of the tread rubber.

[0005] With the accelerated implementation of international carbon tariff policies and bills represented by the "EU Carbon Border Adjustment Mechanism (CBAM)", the demand for low-carbon and green development continues to rise. Rubber tire enterprises are also under pressure to green transition and are committed to reducing the environmental impact of the production process. Zinc oxide in tire wear debris has been proven to cause environmental water pollution. The European Commission's 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. SUMMARY

[0006] The main purpose of the present application is to provide a continuous masterbatch preparation method, a rubber product and an off-road tire to solve the problems of insufficient wear resistance and zinc pollution of off-road tires in the prior art.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a continuous masterbatch preparation method is provided, which comprises: step S1, mixing and pre-reacting an antioxidant, a vulcanization system medicine and a catalyst to obtain a vulcanization aid, the pre-reaction temperature is 100-190 ℃, and the reaction time is 1 min-120 min; step S2, mixing and stirring the mixing raw materials with the first solvent to obtain a premix, the mixing raw materials include rubber, vulcanization aid, white carbon black and silane coupling agent; step S3, solvent separation of the premix to obtain a masterbatch; step S4, mixing and vulcanizing the masterbatch with other aids to obtain a vulcanized rubber, the other aids include accelerators and sulfur.

[0008] Further, the catalyst includes stearic acid;

[0009] Preferably, 0.5-15 parts by weight of antioxidant, 0.5-15 parts by weight of vulcanization system medicine and 0.5-15 parts by weight of stearic acid are added in the pre-reaction;

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

[0011] Preferably, the catalyst further includes 0.1-10 parts by weight of zinc oxide, and the zinc oxide is filtered out after the pre-reaction is completed.

[0012] Further, the pre-reaction temperature is 110-170 ℃, and the reaction time is 5 min-50 min.

[0013] Furthermore, the vulcanization system includes any one or more of vulcanizing agents and accelerators, and the accelerators include any one or more of sulfonamide vulcanization accelerators, sulfenamide vulcanization accelerators, and thiazole vulcanization accelerators. Preferably, the accelerator is selected from any one or more of CZ, DZ, DM, M, and NS.

[0014] And / or, the antioxidant is a p-phenylenediamine antioxidant.

[0015] Preferably, the antioxidant is selected from any one or more of 4020 (6PPD), 4010NA (IPPD), and 7PPD;

[0016] Preferably, the antioxidant is a compound having the structure of Formula I:

[0017] Formula I

[0018] 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.

[0019] Further, step S2 includes: mixing rubber with a first solvent to obtain a rubber solution, mixing the rubber solution with compounding raw materials other than rubber, and stirring to obtain a premix;

[0020] 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;

[0021] Preferably, 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.

[0022] Further, the mixing raw materials include 100 parts of rubber, 1.5-20 parts of vulcanization aids, 45-80 parts of white carbon black, and 0-15 parts of silane coupling agent, by weight.

[0023] Preferably, the mixing raw materials further include one or more of oil, antioxidant, coupling agent, active agent, antioxidant, heat stabilizer, light stabilizer, flame retardant, dye, pigment, plasticizer, softener, processing aid, vulcanizing agent, and accelerator.

[0024] Further, the rubber is selected from one or more of natural rubber, polyisoprene rubber, polystyrene-butadiene rubber, and polybutadiene rubber; preferably, the polystyrene-butadiene rubber is used in an amount of 0-100 parts by weight, more preferably 20-100 parts by weight, based on 100 parts by weight of the rubber; preferably, the polystyrene-butadiene rubber has a styrene monomer combined content of 10 wt% to 50 wt%, and a 1,2-vinyl molar content of 15% to 70% in butadiene;

[0025] And / or, the white carbon black includes any one or more of Zeosil® 1165MP, Zeosil® 1200MP, Zeosil® Premium, and HCSIL-900MP;

[0026] Preferably, the white carbon black has a specific surface area of 10-500 m 2 / g, more preferably 10-300 m 2 / g, further preferably 100-300 m 2 / g; and the white carbon black has an oil absorption value of 20-350 mL / 100g, preferably 25-300 mL / 100g, more preferably 30-290 mL / 100g;

[0027] And / or, the accelerator includes sulfonamide vulcanization accelerator, sulfenamide accelerator, and thiazole vulcanization accelerator, preferably the accelerator includes any one or more of CZ, DCBS, MBTS, MBT, and TBBS;

[0028] And / or, the silane coupling agent includes any one or more of bis(triethoxysilyl)tetrasulfide and disulfide, 3-thiocyanatopropyl-triethoxysilane, γ-mercaptopropyl-trimethoxysilane, zirconate coupling agent, phthalate coupling agent, and nitro coupling agent.

[0029] Further, the solvent separation includes any one of evaporation method, low-pressure vacuum drying method, heating drying method, spray drying method, expansion drying method, flash method, and mechanical drying method;

[0030] Preferably, the step S3 comprises, after the solvent separation of the premix, a drying treatment to obtain the masterbatch, the drying treatment being heating drying and / or mechanical drying.

[0031] Preferably, the vulcanization temperature of the vulcanization treatment is 130-160 DEG C, and the vulcanization time is 0.5-3 hours.

[0032] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a rubber product is provided, which is prepared by any one of the above-mentioned preparation methods.

[0033] According to another aspect of the present application, an off-road tire is provided, which comprises the above-mentioned rubber product.

[0034] By the technical solution of the present application, the vulcanization aid is prepared by pre-reaction of the antioxidant and the vulcanization system medicine, and the active intermediate can be generated, which has the effect of promoting vulcanization, plays the role of activating the accelerator in advance, and can replace the role of zinc oxide. Further, the vulcanization aid is wet-mixed with the rubber and the filler white carbon black, so that the filler is uniformly dispersed, the filler can be all white carbon black, the influence of the rubber on the environment is further reduced, and the rubber is more green and environmentally friendly. The rubber prepared by the above-mentioned method not only has good rubber performance, but also realizes zinc-free emission, is friendly to the environment, and can well meet the demand of the off-road tire for performance and environmental adaptability and friendliness. BRIEF DESCRIPTION OF DRAWINGS

[0035] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application and the explanation thereof serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0036] Figure 1 A test photo of a tire prepared from the vulcanized rubber of the present application Comparative Example 1 is shown;

[0037] Figure 2 A test photo of a tire prepared from the vulcanized rubber of the present application Example 1 is shown. DETAILED DESCRIPTION

[0038] It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict. The present application will be described in detail below with reference to the examples.

[0039] As analyzed in the background art of the present application, there are problems of insufficient wear resistance of the off-road tire and zinc pollution in the prior art. In order to solve the problem, the present application provides a continuous masterbatch preparation method, a rubber product and an off-road tire.

[0040] According to an exemplary embodiment of the present application, a continuous masterbatch preparation method is provided, which comprises: step S1, mixing and pre-reacting an antioxidant, a vulcanization system medicine and a catalyst to obtain a vulcanization aid, the pre-reaction temperature is 100-190 DEG C, and the reaction time is 1 min-120 min; step S2, mixing and stirring the mixing raw material and the first solvent to obtain a premix, the mixing raw material comprises rubber, vulcanization aid, white carbon black and silane coupling agent; step S3, solvent separation of the premix to obtain a masterbatch; step S4, mixing and vulcanizing the masterbatch with other aids to obtain a vulcanized rubber, and the other aids include accelerant and sulfur.

[0041] The present application can generate active intermediates by pre-reacting the antioxidant and the vulcanization system medicine to prepare the vulcanization aid, the active intermediates have the effect of promoting vulcanization, which plays the role of activating the accelerant in advance, so that the active intermediates can replace the role of zinc oxide. Further, the vulcanization aid is wet-mixed with rubber and filler white carbon black, so that the filler is uniformly dispersed, the filler can be all white carbon black, which further reduces the influence of rubber on the environment and is more green and environmentally friendly. The rubber prepared by the above method not only has good rubber performance, but also realizes zinc-free emission, is friendly to the environment, and can well meet the demand of off-road tire for performance and environmental adaptability and friendliness.

[0042] In some exemplary embodiments of the present application, the catalyst in the pre-reaction includes stearic acid, which can more efficiently catalyze the reaction of the antioxidant and the vulcanization system medicine to generate active intermediates. Taking phenylenediamine antioxidant and 2-thiobenzothiazole vulcanization system medicine as an example, the reaction in the pre-reaction is shown in the following reaction equation, and the product has the effect of promoting vulcanization reaction.

[0043]

[0044] In some preferred embodiments of the present application, 0.5-15 parts by weight of the antioxidant, 0.5-15 parts by weight of the vulcanization system medicine and 0.5-15 parts by weight of the stearic acid are added in the pre-reaction, and the product has better effect of promoting rubber crosslinking.

[0045] In some preferred embodiments of the present application, in order to improve the efficiency of the pre-reaction, the pre-reaction is carried out in the second solvent, which can uniformly disperse the catalyst, antioxidant and vulcanization system medicine participating in the pre-reaction and promote the reaction. The second solvent of the pre-reaction system can be removed first and then subjected to the treatment of step S2, or can be directly used in step S2 and combined with rubber.

[0046] The second solvent in the pre-reaction can dissolve stearic acid, antioxidant, and vulcanization system medicine involved in the pre-reaction, and has no adverse effect on the reaction of the antioxidant and the vulcanization system medicine, and can be selected in the prior art. Preferably, the second solvent is selected from any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene, and xylene, which not only has good solubility for stearic acid, antioxidant, and vulcanization system medicine, but also is conducive to the pre-reaction and improves the reaction efficiency.

[0047] The amount of the solvent added has no specific requirement and can be adjusted according to the solubility of the pre-reaction raw materials, and the stearic acid, antioxidant, and vulcanization system medicine can be dissolved.

[0048] In some embodiments of the present application, the catalyst in the pre-reaction also includes zinc oxide, and the amount of zinc oxide is preferably 0.1-10 parts by weight. After the pre-reaction is completed, the zinc oxide is filtered out. By adding zinc oxide, the activity of the pre-reaction product can be improved, the performance of the rubber compound is further improved, and since other components except zinc oxide in the pre-reaction can be dissolved in the second solvent, the zinc oxide can be conveniently filtered out, and the zinc-free vulcanization aid and the zinc-free rubber prepared finally can also be achieved, thereby avoiding the environmental problems caused by zinc.

[0049] In some preferred embodiments of the present application, in order to further improve the efficiency and product effect of the pre-reaction, the reaction temperature of the pre-reaction is 110-170 ℃, and the reaction time is 5 min-50 min.

[0050] The vulcanization system medicine involved in the pre-reaction can be selected in the prior art, and the present application has no particular limitation. As an example, the vulcanization system medicine includes any one or more of vulcanizing agents and accelerators. Preferably, the vulcanization system medicine added in the pre-reaction is any one or more of the accelerators, and the vulcanizing agent is added again in the process of preparing the rubber product.

[0051] The accelerator includes any one or more of, but is not limited to, sulfonamide vulcanization accelerator, sulfenamide vulcanization accelerator, and thiazole vulcanization accelerator, and is preferably any one or more of sulfenamide accelerator and thiazole accelerator. In some typical embodiments of the present application, the accelerator is selected from any one or more of CZ, DZ, DM, M, and NS.

[0052] The antioxidant can also be selected from the prior art, and is preferably a p-phenylenediamine antioxidant. As an example, the antioxidant is selected from any one or more of 4020 (6PPD), 4010NA (IPPD), and 7PPD.

[0053] In some preferred embodiments of the present application, the antioxidant is a compound having the structure of Formula I. In Formula I, R 1 a chain hydrocarbon group selected from C1-C 18 a cycloaliphatic group selected from C3-C 18 an aromatic group selected from C6-C 18 R 2 , R 3 , R 4 , R 5 a chain hydrocarbon group selected from C1-C 18 R 2 and R 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 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 has a value of 1, and at least one of y and z has a value of 1.

[0054] Formula I

[0055] The antioxidant having the structure has not only good effect, but also is not easy to produce harmful substances, and is more friendly to the environment.

[0056] In some embodiments of the present application, the vulcanization aid described above can also be prepared as a masterbatch type vulcanization aid, i.e., after pre-reaction, the pre-reaction product system is mixed with rubber to prepare a masterbatch type vulcanization aid. In some embodiments thereof, the method for mixing the pre-reaction product system with rubber includes first mixing or second mixing, the first mixing including: removing the solvent after mixing the pre-reaction product system with rubber; and the second mixing including: mixing the pre-reaction product system with rubber after removing the solvent.

[0057] Preferably, the rubber in the masterbatch type vulcanization aid described above can be any one or more of natural polymers or synthetic polymers, and is preferably any one or more of natural rubber, styrene butadiene rubber, isoprene rubber, natural gutta-percha, polyisoprene rubber, butadiene rubber, halogenated butyl rubber, and ethylene-propylene-diene rubber; preferably, the molecular weight of the rubber is 1 kilo to 40 million, further preferably 5 kilo to 30 million, and more preferably 10 kilo to 8 million.

[0058] In some typical embodiments of the present application, the step S2 comprises mixing the rubber with the first solvent to obtain a rubber solution, and mixing the rubber solution with the mixing raw materials other than the rubber to obtain the premix. Mixing the rubber with the first solvent first is easy to operate and facilitates the uniform dispersion of the mixing raw materials in the solvent, thereby further improving the performance of the prepared rubber compound. Preferably, the concentration of the rubber in the rubber solution is 1% by weight to 60% by weight, further preferably 5% by weight to 40% by weight, and more preferably 10% by weight to 30% by weight, which better balances the amount of solvent and the uniform dispersion of the mixing raw materials.

[0059] The first solvent is a good solvent for rubber, and can be specifically a fatty hydrocarbon solvent, an aromatic hydrocarbon solvent, a chlorinated hydrocarbon solvent, a ketone solvent, an ether solvent, and an ester solvent. The fatty hydrocarbon solvent includes but is not limited to various solvent naphthas, naphthenes, substituted naphthenes, and n-alkanes. The aromatic hydrocarbon solvent includes but is not limited to benzene, toluene, xylene, and styrene. The chlorinated hydrocarbon solvent includes but is not limited to dichloromethane, trichloromethane, carbon tetrachloride, dichloroethane, chlorobenzene, and tetrachloroethylene.

[0060] The rubber can be selected from the prior art. In some preferred embodiments of the present application, the rubber is selected from one or more of natural rubber, polyisoprene rubber, polystyrene-butadiene rubber, and polybutadiene rubber. Preferably, the amount of polystyrene-butadiene rubber is 0-100 parts by weight, and more preferably 20-100 parts by weight, based on 100 parts by weight of the rubber. Preferably, the styrene monomer content of the polystyrene-butadiene rubber is 10 wt% to 50 wt%, and the molar content of 1,2-vinyl in butadiene is 15% to 70%, i.e., the butadiene monomer in the polystyrene-butadiene rubber includes 1,2-butadiene and 1,4-butadiene, wherein the molar amount of 1,2-vinyl accounts for 15% to 70% of the total molar amount of butadiene monomers. The polystyrene-butadiene rubber can be one or more of a solution polystyrene-butadiene rubber or an emulsion polystyrene-butadiene rubber.

[0061] Further, the amount of natural rubber is 0-100 parts by weight, and the amount of polyisoprene rubber is 0-100 parts by weight, based on 100 parts by weight of the rubber. The amount of polybutadiene rubber is 0-50 parts by weight, and preferably 0-30 parts by weight, based on 100 parts by weight of the rubber.

[0062] The white carbon black can be selected from the prior art. In some embodiments of the present application, the white carbon black includes but is not limited to any one or more of Zeosil®1165MP, Zeosil®1200MP, Zeosil®Premium, and HCSIL-900MP.

[0063] Preferably, the specific surface area of the white carbon black is 10-500 m 2 / g, more preferably 10-300 m 2 / g, further preferably 100-300 m 2 / g; the oil absorption value of the white carbon black is 20-350 mL / 100g, preferably 25-300 mL / 100g, more preferably 30-290 mL / 100g.

[0064] In some embodiments of the present application, the silane coupling agent includes, but is not limited to, any one or more of bis(triethoxysilyl)tetrasulfide and disulfide, 3-thiocyanatopropyl-triethoxysilane, gamma-mercaptopropyl-trimethoxysilane, zirconate coupling agent, phthalate coupling agent and nitro coupling agent.

[0065] In some typical embodiments of the present application, the mixing raw materials include 100 parts of rubber, 1.5-20 parts of vulcanization aid, 45-80 parts of white carbon black and 0-15 parts of silane coupling agent, in terms of weight parts, wherein the parts of the vulcanization aid do not contain solvent.

[0066] Other additives can also be added to the mixing raw materials, such as one or more of oil, antioxidant, coupling agent, active agent, antioxidant, heat stabilizer, light stabilizer, flame retardant, dye, pigment, plasticizer, softener, processing aid, second vulcanizing agent and second accelerator. The amount of the above-mentioned additives is the conventional amount, or adjusted according to the actual requirements, which is not particularly limited in the present application.

[0067] It should be noted that the preparation method of the present application can obtain the effect equivalent to zinc oxide on the basis of adding the above-mentioned vulcanization aid, therefore, without adding zinc oxide as an additive for environmental protection.

[0068] The specific types of the above-mentioned additives can be selected in the prior art, and the preparation method of the present application is not particularly limited. As an example, the second accelerator includes sulfonamide vulcanization accelerator, sulfenamide accelerator and thiazole vulcanization accelerator, preferably, the second accelerator includes any one or more of CZ, DCBS, MBTS, MBT and TBBS; the softener includes, but is not limited to, one or more of oil, resin, wherein the oil includes, but is not limited to, aromatic oil, naphthenic oil, and the resin is one or more of tackifying resin and tear-resistant resin, and the amount of the softener is 0-20 parts by weight, preferably 0-10 parts by weight.

[0069] The step S2 above can be immediately followed by the next step, or can be stopped for a certain period of time, and during the stopping period, heating or no heating can be applied, when heating is applied, the temperature is 10-200 ℃, and when the heating temperature is higher than the boiling point of the solvent, the heating needs to be carried out in a pressure container.

[0070] In the step S3 above, the first solvent in the premix prepared in the step S2 is removed to obtain the masterbatch, and the method for solvent separation can be selected from the prior art. In some embodiments of the present application, the solvent separation includes any one of spray drying, evaporation, heating drying, low-pressure vacuum drying, expansion drying, flash evaporation, and mechanical drying.

[0071] In some embodiments of the present application, the spray drying is used for solvent separation, and the atomization method can be centrifugal atomization, pressure atomization, or two-fluid atomization. In some embodiments of the present application, the evaporation is used for solvent separation, and the evaporation is carried out using an oven or a drying plate. If the heating drying is used for solvent separation, the heating drying is oven drying or air drying. If the low-pressure vacuum drying is used for solvent separation, the low-pressure vacuum drying is volatilization of the solvent or suction filtration under a pressure of vacuum to less than one atmosphere, and the pressure is preferably -0.1 MPa to 0, more preferably -0.09 MPa to 0, and most preferably -0.08 MPa to 0. If the expansion drying is used for solvent separation, the expansion drying is first heating and then sudden release of pressure, and the solvent is flash evaporated by a screw expansion dryer, preferably a screw expansion dryer with a pushing force of 0-20 MPa, more preferably 1-10 MPa, a decreasing pitch, heat generated by friction, a sudden drop in outlet pressure, expansion and relaxation of the rubber strip, and flash evaporation of the solvent in the rubber strip. If the flash evaporation is used for solvent separation, the flash evaporation is at least one of normal pressure flash evaporation or reduced pressure flash evaporation, and the flash evaporation is 1-3 stages. If the mechanical drying is used for solvent separation, the mechanical drying is carried out using an open mill, a kneader, an internal mixer, or a screw extruder, and the working temperature of the mechanical drying is 20-250 ℃.

[0072] In some embodiments of the present application, when the solid content in the rubber compound is less than 98 wt%, in order to further remove the solvent or moisture in the rubber compound, the step S3 includes, after the solvent separation of the premix, drying treatment to obtain the masterbatch, and the drying treatment is heating drying and / or mechanical drying.

[0073] The solvent separated in the solvent separation and drying treatment in the step S3 above is recycled, and the method for recovering the solvent can use any known method in the art, such as surface condensation or direct contact condensation of the vaporized solvent, and when the direct contact condensation is used, the cooling agent can be water.

[0074] The drying treatment can be heating drying or mechanical drying alone, or heating drying followed by mechanical drying, or mechanical drying followed by heating drying, or mechanical drying with simultaneous heating drying at a temperature of 10-250°C, or heating drying in a gaseous medium comprising at least one of air, nitrogen, water vapor, and CO2.

[0075] In step S4, the masterbatch is mixed with accelerators and other additives such as sulfur, and then subjected to vulcanization treatment to obtain a vulcanized rubber. The mixing of the masterbatch with other additives can be done in one step or in multiple steps, and additives can be added during the mixing process, such as the additives added in the mixing of the raw materials.

[0076] In some preferred embodiments of the present application, in step S4, 1-8 parts by mass of accelerators and 1-5 parts by mass of sulfur are added to 100 parts by mass of rubber. The accelerators and sulfur added at this stage can be selected from those known in the art, and the present application does not have any special requirements. The selection of the type of accelerators can also refer to the selection of accelerators in the pre-reaction described above.

[0077] The specific process of mixing and vulcanization treatment can refer to the prior art, and the present application does not have any special requirements. In some embodiments of the present application, a Banbury mixer is used for mixing, with a filling factor of 0.6-0.75. The masterbatch is mixed for 1-5 minutes, then anti-aging agents, resins, etc. are added, and the mixing is continued for 1-5 minutes before the rubber is discharged. The actual temperature of the rubber is 150-160°C. After the rubber is left to stand for more than 8 hours, accelerators and sulfur are added, and the rubber is mixed for 2-5 minutes before it is discharged. The actual temperature is 95-105°C.

[0078] In some preferred embodiments of the present application, in order to further improve the performance of the rubber and make it more suitable for the preparation of off-road tires, the degree of over-vulcanization of the tread rubber is reduced. The vulcanization temperature of the vulcanization treatment is 130-160°C, and the vulcanization time is 0.5-3 hours.

[0079] According to another typical embodiment of the present application, a rubber product is provided, which is prepared by any of the above-mentioned preparation methods.

[0080] The rubber product prepared by the above method, the vulcanization aid is prepared by pre-reaction of the antioxidant and the vulcanization system medicine, the active intermediate can be generated, the active intermediate has the effect of promoting vulcanization, and the effect of the active intermediate can replace the effect of zinc oxide. Further, the vulcanization aid is wet-mixed with the rubber and the filler white carbon black, so that the filler is uniformly dispersed, the filler can be all white carbon black, the influence of the rubber on the environment is further reduced, and the rubber product is more green and environmentally friendly. The rubber prepared by the above method not only has good rubber performance, but also realizes zinc-free emission, is friendly to the environment, and can well meet the requirements of off-road tires on performance, environmental adaptability and friendliness.

[0081] According to another typical embodiment of the present application, an off-road tire is provided, which comprises the above rubber product. The off-road tire made of the above rubber product not only has excellent performance, but also is friendly to the environment.

[0082] The beneficial effects that can be achieved by the present application will be further illustrated below in combination with examples and comparative examples.

[0083] The sources or technical parameters of the raw materials or reagents used in the examples and comparative examples are as follows:

[0084] Styrene-butadiene rubber, ESBR1502, standard glue;

[0085] White carbon black: HCSIL-900MP, specific surface area 218 m 2 / g, oil absorption value 210 mL / 100g, Wuxi Hengcheng Silicon Industry Co., Ltd.;

[0086] Silane coupling agent: Si69, Sure Chemical Silicon Co., Ltd.;

[0087] Anti-tear resin: SCR300, Jiangsu Lingshang New Material Co., Ltd.;

[0088] Stearic acid, Taiko Browning (Zhangjiagang) Co., Ltd. product;

[0089] Zinc oxide, Shijiazhuang Hetong Zinc Industry Co., Ltd. product;

[0090] Protective wax, Qingdao Jinxian Chemical Co., Ltd. product;

[0091] Antioxidant RD, Sinopec Nanjing Chemical Industry Co., Ltd. product;

[0092] Antioxidant 4020, Jiangsu Shengao Chemical Technology Co., Ltd. product;

[0093] Environment-friendly antioxidant , self-synthesized

[0094] Accelerator CZ, product of Shandong Shangshun Chemical Co., Ltd.

[0095] Accelerator DPG, product of Commy Chemical Co., Ltd.

[0096] Sulfur, product of Liaoning Chaoyang Tianming Industry and Trade Co., Ltd.

[0097] The equipment used in the examples and comparative examples is shown in Table 1.

[0098] Table 1

[0099]

[0100] Comparative Example 1

[0101] In an internal mixer, 55 parts (all parts by weight) of white carbon black, 5.5 parts of silane coupling agent Si69 and 100 parts of ESBR1502 were mixed and kneaded for 2 min, then 4 parts of zinc oxide, 1 part of stearic acid, 1.5 parts of antioxidant 4020, 1.5 parts of antioxidant RD, 1 part of protective wax, 6 parts of anti-tear resin were added and continued to be mixed and kneaded for 3 min, and then the rubber was discharged. The measured temperature of the rubber was 150-160 ℃. After the mixed rubber was stored for 8 hours, 2 parts of accelerator CZ, 2.1 parts of accelerator DPG and 1.4 parts of sulfur were added in the internal mixer and mixed and kneaded for 2 min to obtain the final rubber. The measured temperature of the final rubber was 95-105 ℃, and the final rubber was rolled out. After the final rubber was stored for 8 hours, it was vulcanized in a flat vulcanizing machine at 140 ℃ for 2 hours to obtain dry vulcanized rubber D1.

[0102] Comparative Example 2

[0103] After 55 parts of white carbon black and 5.5 parts of Si69 were added to 100 parts of ESBR1502 in n-hexane solution and mixed, they were continuously injected into a reactor, and the solvent was separated by pressure atomizing spray drying to obtain masterbatch D2. After the masterbatch D2 was added to an internal mixer and mixed for 1 min, 4 parts of zinc oxide, 1 part of stearic acid, 1.5 parts of antioxidant 4020, 1.5 parts of antioxidant RD, 1 part of protective wax, and 6 parts of anti-tear resin were added and continued to be mixed and kneaded for 3 min, and then the rubber was discharged. The measured temperature of the rubber was 150-160 ℃. After the mixed rubber was stored for 8 hours, 2 parts of accelerator CZ, 2.1 parts of accelerator DPG and 1.4 parts of sulfur were added in the internal mixer and mixed and kneaded for 2 min to obtain the final rubber. The measured temperature of the final rubber was 95-105 ℃, and the final rubber was rolled out. After the final rubber was stored for 8 hours, it was vulcanized in a flat vulcanizing machine at 140 ℃ for 2 hours to obtain continuous vulcanized rubber D2.

[0104] Example 1

[0105] Preparation of zinc-free vulcanization aid:

[0106] Mix 1 part (all parts by weight) of stearic acid, 1.5 parts of antioxidant 4020, and 2 parts of vulcanization accelerator CZ in octanol, pre-react at 150 °C for 30 min, remove the solvent, and obtain a vulcanization aid;

[0107] Mix the above 4.5 parts of vulcanization aid, 55 parts of white carbon black, and 5.5 parts of silane coupling agent Si69 in a solution of 100 parts of ESBR1502 in n-hexane (rubber concentration of 25 wt%), continuously inject into a reactor, and separate the solvent by pressure atomized spray drying to obtain masterbatch A. After adding masterbatch A into an internal mixer and mixing for 1 min, add 1.5 parts of antioxidant RD, 1 part of protective wax, and 6 parts of tear-resistant resin, continue mixing for 3 min, discharge the rubber compound, and measure the temperature of the rubber compound as 150 °C-160 °C. After stopping the mixing for 8 hours, add 2.1 parts of accelerator DPG and 1.4 parts of sulfur into the internal mixer, mix for 2 min, discharge the rubber compound, measure the temperature of the final rubber compound as 95 °C-105 °C, and pass the rubber compound through the rollers. After stopping the mixing for 8 hours, vulcanize the final rubber compound in a flat vulcanization machine at 140 °C for 2 hours to obtain continuously prepared vulcanized rubber A.

[0108] Example 2

[0109] Mix 1 part of stearic acid, 1.5 parts of self-synthesized environmentally friendly antioxidant , and 2 parts of vulcanization accelerator TBS in octane, pre-react at 120 °C for 75 min to obtain a vulcanization aid solution with a solid content of 20%.

[0110] Mix the above vulcanization aid solution, 55 parts of white carbon black, 5.5 parts of Si69, 1 part of protective wax, and 6 parts of tear-resistant resin in a solution of 100 parts of ESBR1502 in n-hexane (rubber concentration of 20 wt%), continuously inject into a reactor, and dry using an internal mixer and an open mill at a drying temperature of 120 °C-150 °C to obtain masterbatch B. After adding masterbatch B into an internal mixer and mixing for 1 min, add 2.1 parts of accelerator DPG and 1.4 parts of sulfur, continue mixing for 2 min, discharge the rubber compound, measure the temperature of the final rubber compound as 95 °C-105 °C, pass the rubber compound through the rollers, stop the mixing for 8 hours, and vulcanize the final rubber compound in a flat vulcanization machine at 140 °C for 2 hours to obtain continuously prepared vulcanized rubber B.

[0111] The standards and test instruments used for the test items of the vulcanized rubbers prepared in the above examples and comparative examples are shown in Table 2, and the test results are shown in Table 3.

[0112] Table 2

[0113]

[0114] Table 3

[0115]

[0116] From the table, under the same zinc-containing formula as Comparative Examples 1 and 2, after applying the continuous preparation process, the vulcanized rubber has excellent tensile properties, reduced heat build-up, and significantly improved DIN abrasion. Meanwhile, under the condition of not using zinc oxide, the vulcanized rubber prepared in Examples 1 and 2 has comparable effects to the vulcanized rubber prepared by the continuous preparation process of the zinc-containing formula, and has slightly improved tensile properties, heat build-up properties, and wear resistance.

[0117] The vulcanized rubbers A and B obtained in Examples 1 and 2 are used in the tread of an off-road tire, and no zinc is discharged after testing.

[0118] LT285 / 70R17 tires are prepared using the continuous preparation of the tread rubber of Example 1 and the conventional dry method of the tread rubber, respectively, and are tested on real vehicles, as shown in Figure 1 and Figure 2 wherein Figure 1 is a tire prepared from the vulcanized rubber of Comparative Example 1, Figure 2 is a tire prepared from the vulcanized rubber of Example 1. The product of Example 1 has a better appearance, and the abrasion index is increased by more than 20%.

[0119] From the above description, it can be seen that the above-mentioned examples of the present application achieve the following technical effects: The present application prepares a vulcanization aid by pre-reacting the antioxidant with the vulcanization system chemicals, which can generate an active intermediate. The active intermediate 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. Further, the vulcanization aid is wet-mixed with rubber and filler white carbon black, so that the filler is uniformly dispersed, and the filler can be all white carbon black, further reducing the environmental impact of rubber and being more green and environmentally friendly. The rubber prepared by the above method not only has good rubber properties, but also realizes zinc-free discharge, is friendly to the environment, and can well meet the needs of off-road tires for performance and environmental adaptability and friendliness.

[0120] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A process for the preparation of a continuous masterbatch, characterized in that, The application relates to a vulcanization aid and a preparation method thereof. Step S1: a preservative, a vulcanization system medicine and a catalyst are mixed to perform pre-reaction, the catalyst comprises stearic acid, 0.5-15 parts by weight of the preservative, 0.5-15 parts by weight of the vulcanization system medicine and 0.5-15 parts by weight of the stearic acid are added in the pre-reaction, and vulcanization aid is obtained; wherein the pre-reaction temperature is 100-190 DEG C, and the reaction time is 1 min-120 min; the preservative is a p-phenylenediamine preservative; the vulcanization system medicine comprises an accelerator, and the accelerator is selected from any one or more of CZ, DZ, DM, M and NS; Step S2: the mixing raw material is mixed with a first solvent to obtain a premix, the mixing raw material comprises rubber, the vulcanization aid prepared in step S1, white carbon black and a silane coupling agent; Step S3: the premix is subjected to solvent separation to obtain a masterbatch; Step S4: the masterbatch is mixed with other auxiliary agents to perform mixing and vulcanization treatment, and vulcanized rubber is obtained, the other auxiliary agents comprise an accelerator and sulfur.

2. The production method according to claim 1, characterized by, The pre-reaction is performed in a second solvent, and the second solvent is selected from any one or more of butanol, octanol, N-methyl pyrrolidone, octane, nonane, decane, toluene and xylene.

3. The preparation method according to claim 1, characterized in that, The catalyst further comprises 0.1-10 parts by weight of zinc oxide, and the zinc oxide is filtered out after the pre-reaction is completed.

4. The preparation method according to claim 1, characterized in that, The pre-reaction temperature is 110-170 DEG C, and the reaction time is 5 min-50 min.

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

6. The method of claim 1, wherein, The preservative is a compound with 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 preparation method according to claim 1, characterized in that, The step S2 comprises the following steps: the rubber is mixed with a first solvent to obtain a rubber solution, and the rubber solution is mixed with the mixing raw material except the rubber to obtain a premix.

8. The production method according to claim 7, characterized by, The concentration of the rubber in the rubber solution is 1% by weight-60% by weight.

9. The preparation method according to claim 7, characterized in that, The concentration of the rubber in the rubber solution is 5% by weight-40% by weight.

10. The method of claim 7, wherein, The concentration of the rubber in the rubber solution is 10% by weight-30% by weight.

11. The preparation method according to claim 7, characterized in that, 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.

12. The production method according to claim 1 or 7, characterized by, The mixing raw material comprises 100 parts of rubber, 1.5-20 parts of the vulcanization aid, 45-80 parts of white carbon black and 0-15 parts of the silane coupling agent.

13. The method of claim 12, wherein, The mixing raw material further comprises one or more of oil, a preservative, a coupling agent, an active agent, an antioxidant, a heat stabilizer, a light stabilizer, a flame retardant, a dye, a pigment, a plasticizer, a softener, a processing aid, a vulcanizing agent and an accelerator.

14. The method of claim 12, wherein, The rubber is selected from one or more of natural rubber, polyisoprene rubber, polystyrene-butadiene rubber and polybutadiene rubber; And / or, the white carbon black comprises any one or more of Zeosil (R) 1165MP, Zeosil (R) 1200MP, Zeosil (R) Premium and HCSIL-900MP; The application further relates to a rubber product prepared by using the vulcanization aid. And / or, the silane coupling agent includes any one or more of bis(triethoxysilyl)tetrasulfide and disulfide, 3-thiocyanatopropyl-triethoxysilane, gamma-mercaptopropyl-trimethoxysilane, zirconate coupling agent, phthalate coupling agent and nitro coupling agent.

15. The method of claim 14, wherein, The amount of the polystyrene-butadiene rubber is 0-100 parts by weight based on 100 parts by weight of the rubber.

16. The method of claim 14, wherein, The amount of the polystyrene-butadiene rubber is 20-100 parts by weight based on 100 parts by weight of the rubber.

17. The method of claim 14, wherein, The styrene monomer combined content in the polystyrene-butadiene rubber is 10 wt%-50 wt%, and the molar content of 1,2-vinyl in butadiene is 15%-70%.

18. The method of claim 14, wherein, The specific surface area of the white carbon black is 10-500 m 2 / g.

19. The method of claim 14, wherein, The specific surface area of the white carbon black is 10-300 m 2 / g.

20. The method of claim 14, wherein, The specific surface area of the white carbon black is 100-300 m 2 / g.

21. The method of claim 14, wherein, The oil absorption value of the white carbon black is 20-350 mL / 100g.

22. The method of claim 14, wherein, The oil absorption value of the white carbon black is 25-300 mL / 100g.

23. The method of claim 14, wherein, The oil absorption value of the white carbon black is 30-290 mL / 100g.

24. The method of claim 1, wherein, The solvent separation includes any one of evaporation separation of solvent, low-pressure vacuum drying separation of solvent, heating drying separation of solvent, spray drying separation of solvent, expansion drying, flash separation of solvent and mechanical drying separation of solvent.

25. The method of claim 24, wherein, The step S3 includes, after the solvent separation of the premix, drying treatment to obtain a masterbatch, and the drying treatment is heating drying and / or mechanical drying.

26. The method of claim 24, wherein, The curing temperature of the curing treatment is 130-160 ℃, and the curing time is 0.5-3 hours.

27. A rubber article, characterized by, Prepared by the preparation method of any one of claims 1-26.

28. An off-the-road tire characterized by, The rubber product of claim 27. The rubber product of claim 27.

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