Tread rubber composition with low Pearn effect and preparation method thereof

Abstract

The invention relates to the technical field of tire rubber manufacturing, and discloses a low-Pearn-effect tread rubber composition and a preparation method thereof. The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 60-80 parts by weight of solution polymerized styrene-butadiene rubber, 20-40 parts by weight of butadiene rubber, 50-100 parts by weight of white carbon black, 5.0-30 parts by weight of maleic anhydride modified liquid regenerated rubber and 1.0-2.0 parts by weight of sulfur. The maleic anhydride modified liquid regenerated rubber is adopted in the tread rubber to replace a silane coupling agent Si-69, so that the Pearn effect, rolling resistance and wet ground gripping performance of the tread rubber composition are controlled and effectively improved, emission of volatile organic compounds is effectively reduced, and environmental protection is promoted.

Description

Technical Field

[0001] This invention relates to the field of tire rubber manufacturing technology, and more specifically, to a low Payne effect tread rubber composition and its preparation method. Background Technology

[0002] In the tire manufacturing industry, rolling resistance, Payne effect, and environmental performance of tread compounds are core indicators for evaluating the overall quality of tires. Currently, to reduce rolling resistance, the industry commonly uses a compound system of highly dispersed silica and silane coupling agents (such as Si-69). However, Si-69 is prone to hydrolysis during the mixing process, releasing large amounts of ethanol and volatile organic compounds (VOCs). This not only increases the investment and operating costs of factory exhaust gas treatment equipment but also leads to the risk of early scorching of the rubber compound in the later stages of mixing, affecting production stability.

[0003] More importantly, the residual free ethanol after silane hydrolysis slowly migrates and precipitates out during tire use, disrupting the bonding interface between silica and rubber molecules, causing secondary agglomeration of silica, and leading to the Payne effect. The rolling resistance increases significantly. The exacerbation of the Payne effect will deteriorate the dynamic mechanical properties of the rubber compound, not only causing a rebound increase in rolling resistance, but also reducing the wear resistance and fatigue resistance of the tread compound, thus shortening the tire's service life.

[0004] Meanwhile, the global annual production of waste tires continues to grow, making their recycling a crucial issue in the environmental protection field. In existing technologies, waste tire pyrolysis can produce liquid recycled rubber. This recycled rubber contains numerous reactive double bonds in its molecular chain, possessing potential for chemical modification. However, it is currently only used as a low-cost filler, and the reactivity of its double bonds has not been effectively developed for coupling functions, resulting in low added value of waste tire resources. Chinese invention patent CN202510682183.8 discloses a tread rubber composition containing modified liquid rubber. This modified liquid rubber is obtained by melt grafting unsaturated recycled liquid rubber from waste tires with maleic anhydride in the presence of a free radical initiator. The addition of modified liquid rubber improves the interfacial bonding between silica and the rubber composition, weakens the Payne effect, enhances the wear resistance of the rubber composition, and does not affect the rolling resistance and wet skid resistance of the rubber composition, meeting the low energy consumption requirements of new energy vehicles. However, this invention still uses Si-69.

[0005] Therefore, there is an urgent need to develop a new type of coupling material that uses waste tires as raw materials, can completely replace Si-69, and can form a stable bond structure with silica, so as to achieve a synergistic improvement in low VOC emissions, low Payne effect and high dynamic mechanical properties, and promote the tire industry to develop towards green and high performance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a low Payne effect tread rubber composition and its preparation method, which effectively improves the Payne effect, rolling resistance, and wet grip performance of the tread rubber composition, and effectively reduces the emission of volatile organic compounds.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A low Payne effect tread rubber composition, said rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber:

[0009] 60-80 parts by weight of solution-polymerized styrene-butadiene rubber,

[0010] 20-40 parts by weight of butadiene rubber

[0011] 50-100 parts by weight of silica

[0012] Maleic anhydride modified liquid recycled rubber, 8.0-20 parts by weight.

[0013] Sulfur 1.0-2.0 parts by weight;

[0014] The maleic anhydride-modified liquid reclaimed rubber is obtained by grafting maleic anhydride onto liquid reclaimed rubber.

[0015] The maleic anhydride-modified liquid recycled rubber and solution-polymerized styrene-butadiene rubber meet the solubility parameter difference. .

[0016] Preferably, the rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber:

[0017] 65-75 parts by weight of solution-polymerized styrene-butadiene rubber

[0018] 25-35 parts by weight of butadiene rubber

[0019] 70-90 parts by weight of silica

[0020] Maleic anhydride modified liquid recycled rubber, 8.0-20 parts by weight.

[0021] Sulfur 1.0-2.0 parts by weight,

[0022] Accelerator 1.0-5.0 parts by weight,

[0023] Zinc oxide 1.0-4.0 parts by weight,

[0024] Stearic acid 1.0-3.0 parts by weight,

[0025] Anti-aging agent 1.0-5.0 parts by weight.

[0026] Preferably, the anhydride / hydroxyl molar ratio of the anhydride to the hydroxyl groups on the surface of silica is 0.20-0.40.

[0027] Preferably, the maleic anhydride-modified liquid recycled rubber and solution-polymerized styrene-butadiene rubber meet the solubility parameter difference requirement. .

[0028] Preferably, the maleic anhydride-modified liquid reclaimed rubber has an anhydride content of 1.0-2.5 wt%, an iodine value of 15-25 gI2 / 100g, and a number-average molecular weight of 4000-6000 g / mol.

[0029] Preferably, the raw materials of the rubber composition further include 18-25 phr of tackifying resin; preferably, the tackifying resin is α-methylstyrene monomer resin.

[0030] Preferably, the raw materials for the rubber composition also include 5-15 phr of environmentally friendly oil.

[0031] Preferably, the accelerator is selected from N-cyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolyl sulfenamide, N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, N-oxodiethylidene-2-benzothiazolyl sulfenamide, N,N-diisopropyl-2-benzothiazolyl sulfenamide, 2-mercaptobenzothiazolium, dibenzothiazolium disulfide, 2-mercaptobenzothiazolium zinc salt, N-cyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolium sulfinamide, N-oxodiethylidene ... Diethyl-2-benzothiazole sulfenamide, derivatives of dibenzothiazole disulfide, sodium salt of 2-thiol-benzothiazole, 2-benzothiazole disulfide, tetramethylthiuram disulfide, tetramethylthiuram monosulfide, tetraethylthiuram disulfide, tetraisobutylthiuram disulfide, tetrabenzylthiuram disulfide, dipentylthiuram disulfide, bis(1,5-pentylene)thiuram tetrasulfide, bispentamethylenethiuram hexasulfide, tetra(2-ethylhexyl)thiuram disulfide, bispentamethylenethiuram monosulfide, thioamino Formamide, diethylthiourea, dibutylthiourea, trimethylthiourea, di-o-tolylthiourea, diphenylguanidine, di-o-tolyguanidine, triphenylguanidine, o-tolybiguanidine, diphenylguanidine phthalate, zinc ethylphenyl dithiocarbamate, zinc butylphenyl dithiocarbamate, sodium dimethyl dithiocarbamate, zinc dimethyl dithiocarbamate, zinc diethyl dithiocarbamate, zinc dibutyl dithiocarbamate, zinc dipentyl dithiocarbamate, zinc dipropyl dithiocarbamate, zinc pentamethyl dithiocarbamate with piperidine coordination salts, One or more of the following: zinc hexadecyl isopropyl dithiocarbamate, zinc octadecyl isopropyl dithiocarbamate, zinc dibenzyl dithiocarbamate, sodium diethyl dithiocarbamate, piperidine pentamethylene dithiocarbamate, selenium dimethyl dithiocarbamate, tellurium diethyl dithiocarbamate, cadmium dipentyl dithiocarbamate, acetaldehyde-aniline reactants, butyraldehyde-aniline condensates, hexamethylenetetramine, and acetaldehyde-ammonia reactants; more preferably, one or more of the following: N-cyclohexyl-2-benzothiazole sulfenamide and diphenylguanidine.

[0032] Preferably, the antioxidant is selected from N-phenyl-N'-isopropyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris[2,4-di-tert-butylphenyl] phosphite, 2-mercaptobenzimidazole, zinc 2-mercaptobenzimidazole, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, and 2-(2-hydroxyphenyl) One or more of benzimidazole, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, N-phenyl-N'-sec-butyl-p-phenylenediamine, and diphenylguanidine; preferably one or more of N-phenyl-N'-sec-butyl-p-phenylenediamine and diphenylguanidine.

[0033] Preferably, the method for preparing maleic anhydride-modified liquid recycled rubber includes the following steps: adding recycled liquid rubber, maleic anhydride, and dicumyl peroxide into a twin-screw extruder, reacting and extruding under vacuum, pelletizing and drying to obtain granular samples.

[0034] Furthermore, the present invention also provides a method for preparing the rubber composition, comprising the following steps:

[0035] 1) Mixing: A tangential internal mixer is used, with the rotor speed set at 40-55 rpm, the top jack pressure at 4.2±0.2 bar, and the cooling water temperature at 25-40℃.

[0036] a. Add raw rubber, press down the top plug, and hold for 10-20 seconds;

[0037] b. Raise the top bolt, add silica, maleic anhydride modified liquid reclaimed rubber, and auxiliary materials other than vulcanizing agents and accelerators, and press the top bolt to raise the temperature of the rubber compound to 100-110℃.

[0038] c. Raise the top bolt and hold for 6-10 seconds;

[0039] d. Press the top bolt to raise the temperature of the rubber compound to 130-140℃, raise the top bolt, discharge the rubber and press it into sheets to obtain the masterbatch;

[0040] 2) Final sulfur addition: A tangential internal mixer is used, with the rotor speed set at 15-30 rpm, the top jack pressure at 4.2 ± 0.2 bar, and the cooling water temperature at 25-40℃.

[0041] a. Add the mixed masterbatch, vulcanizing agent and accelerator, press the top bolt to heat the rubber compound to 70-80℃;

[0042] b. Raise the top bolt and hold for 6-10 seconds;

[0043] c. Press the top bolt to raise the temperature of the rubber compound to 80-90℃;

[0044] d. Raise the top bolt and hold for 6-8 seconds;

[0045] e. Press the top bolt to heat the rubber compound to 90-95℃, then discharge the rubber and press it into sheets.

[0046] This invention, by employing the above-described scheme, uses maleic anhydride-modified liquid reclaimed rubber to replace the silane coupling agent Si-69 in the tread compound, thereby controlling... Effectively improves the Payne effect of the tread rubber composition ( It improves rolling resistance (60℃ tanδ) and wet grip performance (0℃ tanδ), and effectively reduces the emission of volatile organic compounds (VOCs), thus promoting environmental protection. Detailed Implementation

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0048] The formulations for the examples and comparative examples are shown in Table 1.

[0049] Table 1

[0050]

[0051] Raw material source:

[0052] 1. Solution-polymerized styrene-butadiene rubber (SSBR), SSBR2438, a product of ARLANXEO Singapore Pte Ltd.

[0053] 2. Butadiene rubber BR, BR-9000, a product of Daqing Petrochemical Company.

[0054] 3. Silica, 2115MP, a product of Sanming Zhengyuan Company.

[0055] 4. Silane coupling agent, Si-69, Evonik Industries product.

[0056] 5. Maleic anhydride modified liquid reclaimed rubber: Maleic anhydride is grafted onto waste tire liquid reclaimed rubber. The anhydride content is 1.0-2.5 wt%, the iodine value is 15-25 g I2 / 100g, and the number average molecular weight is 4000-6000 g / mol.

[0057] The preparation method of maleic anhydride-modified liquid recycled rubber is as follows: Recycled liquid rubber, maleic anhydride, and dicumyl peroxide are added to a twin-screw extruder. The screw speed is set to 200 rpm, and the mixture is reacted under vacuum at 190°C for 3 minutes before extrusion. The resulting pellets are then granulated and dried to obtain light yellow granular samples.

[0058] The preparation steps of the tread rubber composition are as follows:

[0059] 1) Mixing: A tangential internal mixer is used, with the rotor speed set at 50 rpm, the top bolt pressure at 4.2 ± 0.2 bar, and the cooling water temperature at 38℃.

[0060] a. Add raw rubber, press down the top plug, and hold for 10-20 seconds;

[0061] b. Raise the top bolt, add silica, maleic anhydride modified liquid reclaimed rubber, and auxiliary materials other than vulcanizing agents and accelerators, and press the top bolt to raise the temperature of the rubber compound to 105°C.

[0062] c. Raise the top bolt and hold for 8 seconds;

[0063] d. Press the top bolt to heat the rubber compound to 135℃, raise the top bolt, discharge the rubber and press it into sheets to obtain the masterbatch;

[0064] 2) Final sulfur addition: A tangential internal mixer is used, with the internal mixer rotor speed set at 25 rpm, the top jack pressure at 4.2 ± 0.2 bar, and the internal mixer cooling water temperature at 35℃;

[0065] a. Add the mixed masterbatch, vulcanizing agent and accelerator, and press the top bolt to heat the rubber compound to 75℃;

[0066] b. Raise the top bolt and hold for 8 seconds;

[0067] c. Press the top bolt to raise the temperature of the rubber compound to 85℃;

[0068] d. Raise the top bolt and hold for 7 seconds;

[0069] e. Press the top bolt to heat the rubber compound to 90°C, then discharge the rubber and press it into sheets.

[0070] Test metrics:

[0071] 60℃tanδ: refer to GB / T 29611-2013

[0072] 0℃tanδ: refer to GB / T 29611-2013

[0073] Payne effect: obtained by scanning the 0.56%-100% strain range of the rubber compound after vulcanization using RPA. It is used to characterize the strength of filler-filler networks.

[0074] VOCs: Refer to GB / T 35466-2017

[0075] The test results are shown in Table 2.

[0076] Table 2

[0077]

[0078] According to Table 1, Si-69 was added to Comparative Example 1, while maleic anhydride modified liquid recycled rubber was used to replace Si-69 in Examples 1-7.

[0079] Observing Table 2, it can be seen that, compared with Comparative Example 1, Examples 1-7 show a higher Payne effect ( All aspects showed improvement. Specifically, in Examples 2-7, compared to Comparative Example 1, the rolling resistance (60℃ tanδ) and volatile organic compound (VOC) levels decreased, while wet grip (0℃ tanδ) improved. Although the test results of Example 1 were generally better than Comparative Example 1, they were significantly worse than those of Examples 2-7. The improvement in Examples 2-7 was more significant than that in Example 1, indicating that an addition amount of maleic anhydride modified liquid reclaimed rubber of 8.0-20 parts by weight was optimal. Examples 1 and Comparative Examples 2 and 3 show that both excessively high and low ΔSP values ​​are detrimental to the overall performance balance of the rubber compound. Too low a ΔSP leads to excessive compatibility between the maleic anhydride modified liquid reclaimed rubber and SSBR, hindering the uniform dispersion of silica in the rubber matrix; too high a ΔSP results in insufficient compatibility, forming interface defects. Both of these factors lead to deterioration of the dynamic mechanical properties of the rubber compound and increased rolling resistance.

[0080] In summary, the overall improvement effect obtained by replacing the silane coupling agent Si-69 with maleic anhydride-modified liquid reclaimed rubber is significant. Therefore, maleic anhydride-modified liquid reclaimed rubber can completely replace the silane coupling agent Si-69, which can improve the Payne effect of the tread rubber composition on the one hand, and effectively reduce the emission of volatile organic compounds on the other hand.

[0081] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A low Payne effect tread rubber composition, characterized in that, The rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 60-80 parts by weight of solution-polymerized styrene-butadiene rubber, 20-40 parts by weight of butadiene rubber 50-100 parts by weight of silica Maleic anhydride modified liquid recycled rubber, 8.0-20 parts by weight. Sulfur 1.0-2.0 parts by weight; The maleic anhydride-modified liquid reclaimed rubber is obtained by grafting maleic anhydride onto liquid reclaimed rubber. The maleic anhydride-modified liquid recycled rubber and solution-polymerized styrene-butadiene rubber meet the solubility parameter difference. .

2. The low Payne effect tread rubber composition according to claim 1, characterized in that, The rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 65-75 parts by weight of solution-polymerized styrene-butadiene rubber 25-35 parts by weight of butadiene rubber 70-90 parts by weight of silica Maleic anhydride modified liquid recycled rubber, 8.0-20 parts by weight. Sulfur 1.0-2.0 parts by weight, Accelerator 1.0-5.0 parts by weight, Zinc oxide 1.0-4.0 parts by weight, Stearic acid 1.0-3.0 parts by weight, Anti-aging agent 1.0-5.0 parts by weight.

3. A low Payne effect tread rubber composition according to claim 1 or 2, characterized in that, The anhydride / hydroxyl molar ratio of the anhydride to the hydroxyl groups on the surface of silica is 0.20-0.

40.

4. A low Payne effect tread rubber composition according to claim 1 or 2, characterized in that, The maleic anhydride-modified liquid recycled rubber and solution-polymerized styrene-butadiene rubber meet the preferred solubility parameter difference. .

5. A low Payne effect tread rubber composition according to claim 1 or 2, characterized in that, The maleic anhydride-modified liquid reclaimed rubber has an anhydride content of 1.0-2.5 wt%, an iodine value of 15-25 gI2 / 100g, and a number-average molecular weight of 4000-6000 g / mol.

6. A low Payne effect tread rubber composition according to claim 1 or 2, characterized in that, The rubber composition raw materials also include 18-25 phr of tackifying resin; preferably, the tackifying resin is α-methylstyrene monomer resin. And / or, the raw materials of the rubber composition also include 5-15 phr of environmentally friendly oil.

7. A low Payne effect tread rubber composition according to claim 1 or 2, characterized in that, The accelerator is selected from N-cyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolyl sulfenamide, N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, N-oxodiethylene-2-benzothiazolyl sulfenamide, N,N-diisopropyl-2-benzothiazolyl sulfenamide, 2-mercaptobenzothiazolium, dibenzothiazolium disulfide, 2-mercaptobenzothiazolium zinc salt, N-cyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolium sulfinamide, N-oxodiethylene 2-Benzothiazole sulfenamide, derivatives of dibenzothiazole disulfide, sodium salt of 2-thiol benzothiazole, 2-benzothiazole disulfide, tetramethylthiuram disulfide, tetramethylthiuram monosulfide, tetraethylthiuram disulfide, tetraisobutylthiuram disulfide, tetrabenzylthiuram disulfide, dipentylthiuram disulfide, bis(1,5-pentylene)thiuram tetrasulfide, bispentamethylenethiuram hexasulfide, tetra(2-ethylhexyl)thiuram disulfide, bispentamethylenethiuram monosulfide, thiocarbamoyl Amines, diethylthiourea, dibutylthiourea, trimethylthiourea, di-o-tolylthiourea, diphenylguanidine, di-o-tolyguanidine, triphenylguanidine, o-tolybiguanidine, diphenylguanidine phthalate, zinc ethylphenyl dithiocarbamate, zinc butylphenyl dithiocarbamate, sodium dimethyl dithiocarbamate, zinc dimethyl dithiocarbamate, zinc diethyl dithiocarbamate, zinc dibutyl dithiocarbamate, zinc dipentyl dithiocarbamate, zinc dipropyl dithiocarbamate, zinc pentamethyl dithiocarbamate with piperidine, decamethylbenzene dithiocarbamate, zinc dimethyl dithiocarbamate, coordinating salt of zinc pentamethyl dithiocarbamate and piperidine, decamethylbenzene dithiocarbamate, zinc dimethyl ... One or more of the following: zinc hexaalkylisopropyl dithiocarbamate, zinc octadecylisopropyl dithiocarbamate, zinc dibenzyl dithiocarbamate, sodium diethyl dithiocarbamate, piperidine pentamethylene dithiocarbamate, selenium dimethyl dithiocarbamate, tellurium diethyl dithiocarbamate, cadmium dipentyl dithiocarbamate, acetaldehyde-aniline reactant, butyraldehyde-aniline condensate, hexamethylenetetramine, and acetaldehyde-ammonia reactant; preferably one or more of N-cyclohexyl-2-benzothiazole sulfenamide and diphenylguanidine.

8. A low Payne effect tread rubber composition according to claim 1 or 2, characterized in that, The antioxidant is selected from N-phenyl-N'-isopropyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris[2,4-di-tert-butylphenyl] phosphite, 2-mercaptobenzimidazole, zinc 2-mercaptobenzimidazole, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, and 2-(2-hydroxyphenyl) One or more of benzimidazole, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, N-phenyl-N'-sec-butyl-p-phenylenediamine, and diphenylguanidine; preferably one or more of N-phenyl-N'-sec-butyl-p-phenylenediamine and diphenylguanidine.

9. The low Payne effect tread rubber composition according to claim 1, characterized in that, The method for preparing maleic anhydride-modified liquid recycled rubber includes the following steps: adding recycled liquid rubber, maleic anhydride, and dicumyl peroxide into a twin-screw extruder, reacting and extruding under vacuum, pelletizing and drying to obtain granular samples.

10. A method for preparing the rubber composition according to any one of claims 1-8, characterized in that, Includes the following steps: 1) Mixing: A tangential internal mixer is used, with the rotor speed set at 40-55 rpm, the top jack pressure at 4.2±0.2 bar, and the cooling water temperature at 25-40℃. a. Add raw rubber, press down the top plug, and hold for 10-20 seconds; b. Raise the top bolt, add silica, maleic anhydride modified liquid reclaimed rubber, and auxiliary materials other than vulcanizing agents and accelerators, and press the top bolt to raise the temperature of the rubber compound to 100-110℃. c. Raise the top bolt and hold for 6-10 seconds; d. Press the top bolt to raise the temperature of the rubber compound to 130-140℃, raise the top bolt, discharge the rubber and press it into sheets to obtain the masterbatch; 2) Final sulfur addition: A tangential internal mixer is used, with the rotor speed set at 15-30 rpm, the top jack pressure at 4.2 ± 0.2 bar, and the cooling water temperature at 25-40℃. a. Add the mixed masterbatch, vulcanizing agent and accelerator, press the top bolt to heat the rubber compound to 70-80℃; b. Raise the top bolt and hold for 6-10 seconds; c. Press the top bolt to raise the temperature of the rubber compound to 80-90℃; d. Raise the top bolt and hold for 6-8 seconds; e. Press the top bolt to heat the rubber compound to 90-95℃, then discharge the rubber and press it into sheets.

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