A tread rubber composition, its preparation method and application

Abstract

Embodiments of the present invention relate to the technical field of tire rubber materials, and specifically disclose a tread rubber composition, a preparation method thereof, and an application. The tread rubber composition comprises the following raw materials: natural rubber, solution styrene-butadiene rubber, modified silica, sulfur, vulcanization accelerator, scorch retarder, and an appropriate amount of antioxidant. By reasonably using the modified silica and other raw materials, the embodiments of the present invention can effectively optimize the filler dispersion effect, reduce the use of small molecules, improve the abrasion resistance and physical and mechanical properties of the tire, and reduce the rolling resistance of the tire, solving the problem in the prior art that the method of reducing the rolling resistance of the tire by increasing the amount of silica used is prone to deteriorate the filler dispersion performance of the rubber compound. Moreover, the preparation method of the tread rubber composition provided by the embodiments of the present invention is simple and has broad application prospects.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of tire rubber materials, and specifically to a tread rubber composition, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of technology, tires, as a kind of annular elastic rubber product that is mounted on various vehicles or machinery and rolls on the ground, also have higher performance requirements. Currently, the tire industry is also developing towards the direction of energy conservation, safety, and environmental protection.

[0003] Generally, in order to achieve contact with the road surface and ensure the driving performance of the vehicle, most tires need to have high wear resistance and flex fatigue resistance, as well as low rolling resistance and heat generation. Among them, for all-steel radial truck tires, there are also certain requirements for low rolling resistance. Because the fuel consumption caused by the rolling resistance of the tire accounts for about 15% of the total fuel consumption of the vehicle. If the rolling resistance coefficient (RRC) is reduced by 30%, the fuel consumption can be reduced by 4.5%. Therefore, effectively reducing the RRC of the tire to achieve low rolling resistance performance can not only save fuel but also play a significant role in reducing greenhouse gas emissions.

[0004] Currently, in the methods of improving the wet grip of tires and reducing the rolling resistance of tires, the hysteresis loss of the rubber compound can be reduced by increasing the amount of silica used, so as to reduce the rolling resistance of the prepared tires and improve the wet grip ability at the same time. Therefore, in the traditional low-rolling-resistance tread formula, it is a trend to gradually increase the amount of silica used. However, the above technical solutions have the following deficiencies in actual use: In the prior art, the method of reducing the rolling resistance of tires by increasing the amount of silica used is prone to agglomeration because there are a large number of silanol groups on the surface of silica, making it hydrophilic. After the silanization reaction is not fully carried out, it is easy to cause poor dispersion of the rubber compound filler, thus affecting the appearance of the semi-finished product during extrusion and the wear and rolling resistance of the finished tire, resulting in problems affecting the heat generation performance and physical and mechanical properties of the rubber compound. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a tread rubber composition to solve the problem that the method of reducing the rolling resistance of tires by increasing the amount of silica used in the prior art is prone to poor dispersion performance of the rubber compound filler as mentioned in the above background art.

[0006] To achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

[0007] A tread rubber composition comprising the following raw materials: natural rubber, solution-polymerized styrene-butadiene rubber, modified silica, sulfur, vulcanization accelerator, scorch retarder, and an appropriate amount of antioxidant; wherein, the modified silica is prepared by adding silica to a silane coupling agent solution for heating reaction, placing the product after the heating reaction in tetrahydrofuran, adding an excessive amount of glycidyl chloro-isobutyrate, heating, filtering, washing, drying, and then adding cuprous chloride, methyl methacrylate monomer, atom transfer radical polymerization catalyst, ε-caprolactone monomer, stannous octoate under nitrogen protection and stirring and polymerizing at 80-100 °C.

[0008] As a further embodiment of the present invention: The silane coupling agent solution comprises the following raw materials by weight: 10-30 parts of silane coupling agent, 65-75 parts of ethanol, and 5-10 parts of water.

[0009] As a further embodiment of the present invention: The atom transfer radical polymerization catalyst is selected from any one of pentamethyldiethylenetriamine or 2,2'-bipyridine.

[0010] Preferably, the atom transfer radical polymerization catalyst is 2,2'-bipyridine.

[0011] As a further embodiment of the present invention: The tread rubber composition comprises the following raw materials by weight: 60-80 parts of natural rubber; 20-40 parts of solution-polymerized styrene-butadiene rubber; 50-60 parts of modified silica; 1.2-1.6 parts of sulfur; 1.4-1.8 parts of vulcanization accelerator; 0-5 parts of antioxidant; 0.2-0.8 parts of scorch retarder.

[0012] Another object of the embodiments of the present invention is to provide a preparation method of a tread rubber composition. The preparation method of the tread rubber composition comprises the following steps:

[0013] 1) Add all raw materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica to a mixer according to the ratio, add modified silica after pressurization for mixing, and then pressurize and knead until the temperature reaches 150 °C - 160 °C, then discharge the rubber, take out the sheet and cool it to obtain the first-stage kneaded rubber;

[0014] 2) Knead the first-stage kneaded rubber under pressure for multiple times, then add sulfur, vulcanization accelerator, and scorch retarder, after multiple times of pressurizing the upper plug and decompressing the plug, then pressurize and knead until the temperature reaches 105 °C - 125 °C, discharge the rubber, take out the sheet and cool it to obtain the tread rubber composition.

[0015] Another object of the embodiments of the present invention is to provide a tread rubber composition prepared by using the preparation method of the above-mentioned tread rubber composition.

[0016] Another object of the embodiments of the present invention is to provide an application of the above-mentioned tread rubber composition in the preparation of tires. In particular, it is suitable for use as a tire tread material to prepare all-steel radial truck tires.

[0017] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows:

[0018] By reasonably using natural rubber, solution polymerized styrene-butadiene rubber, modified silica, sulfur, vulcanization accelerator, scorch retarder, and an appropriate amount of antioxidant, the tread rubber composition provided by the embodiments of the present invention can effectively optimize the filler dispersion effect. Compared with the traditional low rolling resistance tread formula with an increased amount of silica used, the embodiments of the present invention can reduce the use of small molecules, improve the abrasion resistance and physical and mechanical properties of the tire, and reduce the rolling resistance of the tire, solving the problem in the prior art that increasing the amount of silica used to reduce the rolling resistance of the tire is likely to cause poor filler dispersion performance of the rubber compound. Moreover, the preparation method of the tread rubber composition provided by the embodiments of the present invention is simple, can be used to prepare other types of rubber compositions, and has broad market prospects. Specific Embodiments

[0019] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the embodiments of the present invention, but do not limit the embodiments of the present invention in any form. It should be noted that those of ordinary skill in the art can make several modifications and improvements without departing from the concept of the embodiments of the present invention. These all belong to the protection scope of the embodiments of the present invention.

[0020] A tread rubber composition provided by the embodiments of the present invention specifically relates to a tread rubber composition filled with modified silica, and includes the following raw materials: natural rubber, solution polymerized styrene-butadiene rubber, modified silica, sulfur, vulcanization accelerator, scorch retarder, and an appropriate amount of antioxidant; wherein, the modified silica is obtained by adding silica to a silane coupling agent solution, heating and reacting, placing the product in tetrahydrofuran, adding an excessive amount of glycidyl chloro-isobutyrate, heating, filtering, washing, drying, and then adding copper chloride (CuCl), methyl methacrylate monomer (MMA), ATRP reaction catalyst pentamethyldiethylenetriamine (PMDETA), ε-caprolactone monomer (ε-caprolactone, ε-CL), and ROP reaction catalyst stannous octoate (Sn(Oct)2) under nitrogen protection and stirring and polymerizing at 80-100 °C.

[0021] Preferably, the reaction temperature for the stirring polymerization is 90 °C. Specifically, surface-aminated silica is obtained by adding fumed silica into a silane coupling agent solution, heating and reacting, then filtering, washing, and drying. In tetrahydrofuran (THF), surface-aminated silica and excessive glycidyl chloro-isobutyrate are heated and reacted. After filtration, washing, and drying, surface-aminated silica is grafted with functional groups (-Cl, -OH) that can initiate ATRP and ROP reactions to obtain SiO2-f-Cl / OH. In the last step, SiO2-f-Cl / OH, copper chloride (CuCl), methyl methacrylate monomer (MMA), ATRP reaction catalyst pentamethyldiethylenetriamine (PMDETA), ε-caprolactone monomer (ε-CL), and ROP reaction catalyst stannous octanoate (Sn(Oct)2) are added under nitrogen protection, and stirred and polymerized at 90 °C for 9 h. After the reaction, glacial acetic acid is used to wash away copper chloride, and after filtration, anhydrous ethanol is used for washing, and then filtered and dried to obtain modified fumed silica, denoted as SiO2-g-PMMA / PCL, which is a product with low molecular weight poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL) grafted on the surface of fumed silica.

[0022] As another preferred embodiment of the embodiment of the present invention, the silane coupling agent solution is mixed from the following raw materials in parts by weight: silane coupling agent (10 - 30 parts), ethanol (65 - 75 parts), water (5 - 10 parts).

[0023] Preferably, the silane coupling agent solution is mixed from the following raw materials: silane coupling agent (20 wt%), ethanol (72 wt%), water (8 wt%).

[0024] Among them, the silane coupling agent specifically uses existing products, such as products with models KH550, KH560, KH570, etc. Preferably, silane coupling agent KH-550 is used.

[0025] As another preferred embodiment of the embodiment of the present invention, when preparing the modified fumed silica, the raw materials added in the stirring polymerization include, by weight: 0.8 - 1.2 parts of copper chloride, 500 - 600 parts of methyl methacrylate monomer, 1 - 4 parts of ATRP (Atom Transfer Radical Polymerization) reaction catalyst, 900 - 1100 parts of ε-caprolactone monomer, and 5 - 10 parts of stannous octanoate.

[0026] As another preferred embodiment of the embodiment of the present invention, the ATRP reaction catalyst can be pentamethyldiethylenetriamine or 2,2'-bipyridine.

[0027] Preferably, when preparing the modified silica, in the last step, based on 100 parts by weight of SiO2-f-Cl / OH, 1.112 parts of cuprous chloride (CuCl), 600 parts of methyl methacrylate monomer (MMA), 1.386 parts of ATRP reaction catalyst pentamethyldiethylenetriamine (PMDETA) or 3.504 parts of ATRP reaction catalyst 2,2'-bipyridine, 1000 parts of ε-caprolactone monomer (ε-CL), and 7 parts of ROP reaction catalyst stannous octanoate (Sn(Oct)2) are added under nitrogen protection and stirred for polymerization.

[0028] As another preferred embodiment of the examples of the present invention, the silica is a general term for white powdery X-ray amorphous silicic acid and silicate products, mainly referring to precipitated silica, fumed silica, and ultrafine silica gel, and also including powdery synthetic aluminosilicate and calcium silicate, etc. Further preferably, the raw material used for the modified silica has a BET adsorption specific surface area of 180-220 m 2 / g of silica. Specifically, silica 195GR is selected, for example, the product with the brand ZC-195GR of Fujian ZhengSheng Inorganic Materials Co., Ltd.

[0029] As another preferred embodiment of the examples of the present invention, the tread rubber composition comprises the following raw materials in parts by weight: 60-80 parts of natural rubber; 20-40 parts of solution-polymerized styrene-butadiene rubber; 50-60 parts of modified silica; 1.2-1.6 parts of sulfur; 1.4-1.8 parts of vulcanization accelerator; 0-5 parts of antioxidant; 0.2-0.8 parts of scorch retarder.

[0030] Specifically, the solution-polymerized styrene-butadiene rubber is an elastomer synthesized by anionic solution polymerization of styrene and butadiene under the initiation of organolithium. Specifically, existing products can be used, such as the product with the trade name of Trinseo solution-polymerized styrene-butadiene rubber (S-SBR) SLR 3402, or the product with the trade name of solution-polymerized styrene-butadiene rubber SSBR 1205 of Dongguan Kunhe Plastic Chemical Co., Ltd. It is specifically selected according to needs and is not limited here. Preferably, it is solution-polymerized styrene-butadiene rubber (S-SBR) SLR 3402.

[0031] As another preferred embodiment of the examples of the present invention, the styrene content in the solution-polymerized styrene-butadiene rubber is 12%-18%, and the vinyl content is 25%-35%.

[0032] As another preferred embodiment of the embodiment of the present invention, the tread rubber composition comprises the following raw materials in parts by weight: 60-80 parts of natural rubber; 20-40 parts of solution styrene-butadiene rubber; 50-60 parts of modified silica; 0-8 parts of environmentally friendly aromatic oil (TDAE); 0-3 parts of polyethylene glycol; 2-5 parts of zinc oxide; 1-3 parts of stearic acid; 1-5 parts of antioxidant; 1.2-1.4 parts of sulfur; 1.4-1.6 parts of vulcanization accelerator; 0.4-0.6 parts of scorch retarder.

[0033] It should be noted that sulfur can be divided into ordinary sulfur and insoluble sulfur in terms of type. The solubility of ordinary sulfur in rubber is 1%, and insoluble sulfur is a form of ordinary sulfur, which is prepared by thermal polymerization of ordinary orthorhombic sulfur. The embodiment of the present invention preferably uses ordinary sulfur.

[0034] Preferably, the vulcanization accelerator uses vulcanization accelerator TBBS (N-tert-butyl-2-benzothiazole sulfenamide), and the scorch retarder uses scorch retarder CTP (N-cyclohexylthiophthalimide).

[0035] As another preferred embodiment of the embodiment of the present invention, the mass ratio of the sulfur to the vulcanization accelerator is 76%-100%. A more preferred scheme is that the mass parts of sulfur: the mass parts of vulcanization accelerator = 80%-90%: 1.

[0036] The embodiment of the present invention also provides a preparation method of a tread rubber composition. The preparation method of the tread rubber composition comprises the following steps:

[0037] 1) Add all raw materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica into a mixer according to the proportion, add modified silica after pressurization for mixing, and then pressurize and knead until the temperature reaches 150°C-160°C, then discharge the rubber, take out the sheet and cool it to obtain the first-stage kneaded rubber.

[0038] 2) Subject the first-stage kneaded rubber to multiple pressurized kneadings, then add sulfur, vulcanization accelerator, and scorch retarder. After multiple pressurizations and depressurizations of the upper plug, pressurize and knead until the temperature reaches 105°C-125°C, discharge the rubber, take out the sheet and cool it to obtain the tread rubber composition.

[0039] As another preferred embodiment of the embodiment of the present invention, in the preparation method of the tread rubber composition, the pressure of the upper plug pressurization is 85 bar-125 bar (where 1 bar = 0.1 MPa).

[0040] Preferably, the pressure of the upper plug is 102 bar.

[0041] As another preferred embodiment of the embodiment of the present invention, in the preparation method of the tread rubber composition, the cooling water pressure during cooling is ≥0.01 Mpa, and more preferably ≥0.02 Mpa.

[0042] Preferably, the preparation method of the tread rubber composition specifically includes the following steps:

[0043] First-stage mixing: Add all raw materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica. Apply pressure with the upper plug (20 seconds to 40 seconds), lift the plug and add (50% to 80%) of the modified silica, apply pressure with the upper plug (25 seconds to 45 seconds), lift the plug and add the remaining (20% to 50%) of the modified silica, apply pressure with the upper plug (25 seconds to 45 seconds), lift the plug (5 seconds to 15 seconds), and then apply pressure for mixing for 120 seconds or until discharging the rubber at (150°C to 160°C) and taking out the sheet for cooling;

[0044] Second-stage mixing: Add the first-stage mixed rubber, apply pressure with the upper plug (30 seconds to 60 seconds), lift the plug (5 seconds to 15 seconds), apply pressure for mixing for 100 seconds or until discharging the rubber at (150°C to 160°C) and taking out the sheet for cooling;

[0045] Third-stage mixing: Add the second-stage mixed rubber, apply pressure with the upper plug (30 seconds to 60 seconds), lift the plug (5 seconds to 15 seconds), apply pressure for mixing for 100 seconds or until discharging the rubber at (150°C to 160°C) and taking out the sheet for cooling;

[0046] Fourth-stage mixing: Add the third-stage mixed rubber, sulfur, vulcanization accelerator, and scorch retarder. Apply pressure with the upper plug (20 seconds to 40 seconds), lift the plug (5 seconds to 15 seconds), apply pressure (20 seconds to 40 seconds), lift the plug (5 seconds to 15 seconds), apply pressure (20 seconds to 40 seconds), lift the plug (5 seconds to 15 seconds), and then apply pressure for mixing for 100 seconds or until discharging the rubber at (105°C to 125°C) and taking out the sheet for cooling.

[0047] Among them, the rotor speed: first-stage mixing: 35 rpm to 55 rpm; second-stage mixing: 40 rpm to 55 rpm; third-stage mixing: 40 rpm to 55 rpm; fourth-stage mixing: 15 rpm to 30 rpm.

[0048] The embodiment of the present invention also provides a tread rubber composition prepared by using the above preparation method of the tread rubber composition.

[0049] The embodiment of the present invention also provides a steel radial truck tire, and the tread of the steel radial truck tire comprises the above tread rubber composition.

[0050] The embodiments of the present invention further provide an application of the above-mentioned tread rubber composition in the preparation of tires. In particular, it is suitable for use as a tire tread material to prepare all-steel radial truck tires. Further, it can be applied to the tread of all-steel radial truck tires with low rolling resistance.

[0051] It should be noted that according to the different directions of the cord arrangement in the carcass, the above-mentioned tires can be further divided into ordinary bias tires, belted bias tires and radial tires. Among them, in radial tires, the carcass cords are arranged in the radial direction (arranged at 90° or close to 90° to the crown center line), and there is a belt layer with cords arranged almost close to the circumferential direction to tighten the carcass. Therefore, compared with ordinary bias tires, radial tires have the advantages of good wear resistance, high elasticity, long service life and large load-bearing capacity. They are especially suitable for the use of high-load vehicles. By providing a modified silica-filled tread rubber composition, the embodiments of the present invention can optimize the filler dispersion, reduce the use of small molecules at the same time, improve the wear resistance and physical and mechanical properties of the tires, and reduce the rolling resistance of the tires.

[0052] The following further illustrates the technical effects of the tread rubber composition of the embodiments of the present invention by listing specific examples.

[0053] Example 1

[0054] A tread rubber composition comprising the following raw materials:

[0055] 70 parts by weight of natural rubber;

[0056] 30 parts by weight of solution styrene-butadiene rubber SLR3402;

[0057] 55 parts by weight of silica 195GR;

[0058] 5.5 parts by weight of silane coupling agent Si-69;

[0059] 5 parts by weight of TDAE (environmentally friendly aromatic oil);

[0060] 2 parts by weight of Rhein 37 (specifically using Lanxess chemical processing aid Aflux 37);

[0061] 2 parts by weight of polyethylene glycol PEG3350;

[0062] 3.5 parts by weight of zinc oxide;

[0063] 2 parts by weight of stearic acid;

[0064] 2 parts by weight of antioxidant 4020;

[0065] 1 part by weight of antioxidant RD;

[0066] 1.3 parts by weight of ordinary sulfur;

[0067] 1.5 parts by weight of vulcanization accelerator TBBS;

[0068] 0.5 parts by weight of scorch retarder CTP.

[0069] In this embodiment, the preparation method of the tread rubber composition specifically includes the following steps:

[0070] 1) First-stage mixing: Add all materials except sulfur, vulcanization accelerator, scorch retarder, silica, and TDAE. Apply pressure with the upper ram for 30S, lift the ram and add 65% of the silica, apply pressure with the upper ram for 35S, lift the ram and add the remaining 35% of the silica, apply pressure with the upper ram for 100S or until 120°C, lift the ram and inject oil (TDAE), then apply pressure until 145°C and keep warm for 120S, lift the ram for 10S, apply pressure until 145°C and keep warm for 120S, lift the ram for 10S, apply pressure until 145°C and keep warm for 120S, lift the ram for 10S, then apply pressure for mixing for 120S or until 155°C, discharge the rubber, take out the sheet and cool it.

[0071] 2) Second-stage mixing: Add the first-stage mixed rubber, apply pressure with the upper ram for 40S, lift the ram for 10S, apply pressure for mixing for 100S or until 155°C, discharge the rubber, take out the sheet and cool it;

[0072] 3) Third-stage mixing: Add the second-stage mixed rubber, apply pressure with the upper ram for 40S, lift the ram for 10S, apply pressure for mixing for 100S or until 155°C, discharge the rubber, take out the sheet and cool it;

[0073] 4) Fourth-stage mixing: Add the third-stage mixed rubber, sulfur, vulcanization accelerator, and scorch retarder, apply pressure with the upper ram for 30S, lift the ram for 10S, apply pressure for 30S, lift the ram for 10S, apply pressure for 30S, lift the ram for 10S, then apply pressure for mixing for 100S or until 115°C, discharge the rubber, take out the sheet and cool it to obtain the tread rubber composition.

[0074] Among them, the rotor speed: First-stage mixing: 45 rpm; Second-stage mixing: 50 rpm; Third-stage mixing: 50 rpm; Fourth-stage mixing: 20 rpm. Upper ram pressure: 102 bar; Cooling water pressure: ≥0.02 Mpa.

[0075] It should be noted that the development and application of low rolling resistance tire products are gradually increasing. Currently, the common design features of low rolling resistance and high wet grip tread formulations in the industry are as follows: (1) Using styrene-butadiene rubber: It has low material hysteresis loss and good grip at the same time; (2) Introducing large particle size carbon black: The carbon black has a large particle size and low heat generation; (3) Increasing the amount of silica: Increasing the silica content can reduce the hysteresis loss of the rubber compound and improve the wet grip ability. Among them, increasing the amount of silica used is a very common method. For example, a tire composite material disclosed in a Chinese patent with the publication number CN1908076A can significantly improve the wear resistance of the tire tread and reduce the rolling resistance to a certain extent; a rubber composition containing solution-polymerized styrene-butadiene rubber and other materials provided by a Chinese patent with the publication number CN101792545A has a Tanδ at 60 °C between 0.11 - 0.14; a rubber composition disclosed in a Chinese patent with the publication number CN101113217A can reduce the rolling resistance and improve the wear resistance, wet skid resistance, and handling stability.

[0076] With the improvement of regulations on the energy conservation and environmental protection requirements of tire products, the quality and technical indicators such as tire rolling resistance, which have a great impact on vehicle fuel economy, are becoming increasingly stringent. Low rolling resistance, low fuel consumption, and low noise have become the main indicators for measuring whether a tire meets the requirements of low-carbon economic development. In the above technologies, significantly increasing the amount of silica will lead to the agglomeration effect between silicas, reduce the physical and mechanical properties of the rubber compound, and affect heat generation and tire rolling resistance.

[0077] For example, in this embodiment, the tread rubber composition prepared as the reference formulation uses silica to improve the material properties. The reference formulation adopts the traditional silica formulation heat preservation process and is prepared by mixing in a Banbury mixer. Specifically, the reference formulation uses natural rubber in the raw rubber system and a solution-polymerized styrene-butadiene rubber system, and selects a high proportion of silica in the reinforcing system, which can improve the wet grip performance of the rubber compound and reduce the rolling resistance at the same time. However, the amount of silica is relatively large, and the silica surface contains a large number of hydrophilic silanol groups. It is easy for the particles that have not undergone sufficient silanization reaction to agglomerate, resulting in poor filler dispersion, affecting its combination with rubber, and resulting in poor physical and mechanical properties of the rubber compound. And some free silica will adsorb the vulcanization accelerator, making the vulcanization speed and scorch time of the rubber compound unstable.

[0078] Example 2

[0079] Through multiple formulation experiments on the reference formulation in Example 1, an improved solution was optimized, and a tread rubber composition was provided, including the following raw materials:

[0080] 70 parts by weight of natural rubber;

[0081] 30 parts by weight of solution-polymerized styrene-butadiene rubber SLR3402;

[0082] 55 parts by weight of modified silica;

[0083] 5 parts by weight of TDAE (environmentally friendly aromatic oil);

[0084] 2 parts by weight of Rhein 37 (specifically using Lanxess chemical processing aid Aflux 37);

[0085] 2 parts by weight of polyethylene glycol PEG3350;

[0086] 3.5 parts by weight of zinc oxide;

[0087] 2 parts by weight of stearic acid;

[0088] 2 parts by weight of antioxidant 4020;

[0089] 1 part by weight of antioxidant RD;

[0090] 1.3 parts by weight of ordinary sulfur;

[0091] 1.5 parts by weight of vulcanization accelerator TBBS;

[0092] 0.5 part by weight of scorch retarder CTP.

[0093] In this embodiment, the preparation method of the modified silica is as follows: Add 195GR of silica to a solution composed of silane coupling agent KH550 (20 wt%), ethanol (72 wt%), and water (8 wt%), stir at 40 °C for 4 h, then raise the temperature to 90 °C and stir for 2 h. After filtration, wash with a large amount of absolute ethanol and dry to obtain surface-aminated silica. Add surface-aminated silica and excessive glycidyl chloro-isobutyrate to tetrahydrofuran (THF), stir at room temperature for 1 h, then raise the temperature to 50 °C and stir for 24 h. After filtration, wash with absolute ethanol and dry to obtain a dried product, so that the surface of silica in the dried product is grafted with functional groups (-Cl, -OH) that can initiate ATRP and ROP reactions, denoted as SiO2-f-Cl / OH. In the last step, taking SiO2-f-Cl / OH as 100 parts by mass, under nitrogen protection, add 1.112 parts of copper chloride (CuCl), 600 parts of methyl methacrylate monomer (MMA), 3.504 parts of ATRP reaction catalyst 2,2'-bipyridine, 1000 parts of ε-caprolactone monomer (ε-CL), and 7 parts of ROP reaction catalyst stannous octanoate (Sn(Oct)2), stir and polymerize at 90 °C for 9 h. After the reaction, wash away copper chloride with glacial acetic acid, filter, wash with absolute ethanol, and then filter and dry to obtain the modified silica, denoted as SiO2-g-PMMA / PCL, that is, the surface of 195GR silica is grafted with low molecular weight polymethyl methacrylate (PMMA) and polycaprolactone (PCL).

[0094] In this embodiment, the preparation method of the tread rubber composition specifically includes the following steps:

[0095] 1) First-stage mixing: Add all materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica. Apply pressure with the upper plug for 30 s, lift the plug and add 65% of the modified silica, apply pressure with the upper plug for 35 s, lift the plug and add the remaining 35% of the modified silica, apply pressure with the upper plug for 35 s, lift the plug for 10 s, and then apply pressure for mixing for 120 s or until the temperature reaches 155 °C. Discharge the rubber, take out the sheet and cool it.

[0096] 2) Second-stage mixing: Add the first-stage mixed rubber. Apply pressure with the upper plug for 40 s, lift the plug for 10 s, apply pressure for mixing for 100 s or until the temperature reaches 155 °C. Discharge the rubber, take out the sheet and cool it.

[0097] 3) Third-stage mixing: Add the second-stage mixed rubber. Apply pressure with the upper plug for 40 s, lift the plug for 10 s, apply pressure for mixing for 100 s or until the temperature reaches 155 °C. Discharge the rubber, take out the sheet and cool it.

[0098] 4) Fourth-stage mixing: Add the third-stage mixed rubber, sulfur, vulcanization accelerator, and scorch retarder. Apply pressure with the upper plug for 30 s, lift the plug for 10 s, apply pressure for 30 s, lift the plug for 10 s, apply pressure for 30 s, lift the plug for 10 s, and then apply pressure for mixing for 100 s or until the temperature reaches 115 °C. Discharge the rubber, take out the sheet and cool it to obtain the tread rubber composition.

[0099] Among them, the rotor speed: first-stage mixing: 45 rpm; second-stage mixing: 50 rpm; third-stage mixing: 50 rpm; fourth-stage mixing: 20 rpm. The pressure of the upper plug: 102 bar; the pressure of the cooling water: ≥0.02 Mpa.

[0100] Example 3

[0101] In this embodiment, in order to further optimize the formulation of Example 2, some raw materials are omitted, thereby providing a tread rubber composition, including the following raw materials:

[0102] 70 parts by weight of natural rubber;

[0103] 30 parts by weight of solution styrene-butadiene rubber SLR3402;

[0104] 55 parts by weight of modified silica;

[0105] 3.5 parts by weight of zinc oxide;

[0106] 2 parts by weight of stearic acid;

[0107] 2 parts by weight of antioxidant 4020;

[0108] 1 part by weight of antioxidant RD;

[0109] 1.3 parts by weight of ordinary sulfur;

[0110] 1.5 parts by weight of vulcanization accelerator TBBS;

[0111] 0.5 parts by weight of scorch retarder CTP.

[0112] In this embodiment, the preparation method of the modified silica is as follows: Add silica 195GR to a solution composed of silane coupling agent KH550 (20 wt%), ethanol (72 wt%), and water (8 wt%), stir at 40 °C for 4 h, then raise the temperature to 90 °C and stir for 2 h, filter and wash with a large amount of absolute ethanol, and dry to obtain surface-aminated silica. Add surface-aminated silica and excessive glycidyl chloro-isobutyrate in tetrahydrofuran (THF), stir at room temperature for 1 h, then raise the temperature to 50 °C and stir for 24 h, filter and wash with absolute ethanol, and dry to obtain a dried product, so that the surface of silica in the dried product is grafted with functional groups (-Cl, -OH) that can initiate ATRP and ROP reactions, denoted as SiO2-f-Cl / OH. In the last step, taking SiO2-f-Cl / OH as 100 parts by mass, add 1.112 parts of copper chloride (CuCl), 600 parts of methyl methacrylate monomer (MMA), 3.504 parts of ATRP reaction catalyst 2,2'-bipyridine, 1000 parts of ε-caprolactone monomer (ε-CL), and 7 parts of ROP reaction catalyst stannous octanoate (Sn(Oct)2) under nitrogen protection, stir and polymerize at 90 °C for 9 h, wash away copper chloride with glacial acetic acid after the reaction ends, filter and wash with absolute ethanol, and then filter and dry to obtain the modified silica, denoted as SiO2-g-PMMA / PCL, that is, low-molecular-weight polymethyl methacrylate (PMMA) and polycaprolactone (PCL) are grafted on the surface of silica 195GR.

[0113] In this embodiment, the preparation method of the tread rubber composition specifically includes the following steps:

[0114] 1) First-stage mixing: Add all materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica, apply pressure with the upper plug for 30 s, lift the plug and add 65% of the modified silica, apply pressure with the upper plug for 35 s, lift the plug and add the remaining 35% of the modified silica, apply pressure with the upper plug for 35 s, lift the plug for 10 s, and then apply pressure for mixing for 120 s or until 155 °C, discharge the rubber, take out the sheet and cool it;

[0115] 2) Second-stage mixing: Add the first-stage mixed rubber, apply pressure with the upper plug for 40 s, lift the plug for 10 s, apply pressure for mixing for 100 s or until 155 °C, discharge the rubber, take out the sheet and cool it;

[0116] 3) Third-stage mixing: Add the second-stage mixed rubber, apply pressure with the upper plug for 40 s, lift the plug for 10 s, apply pressure for mixing for 100 s or until 155 °C, discharge the rubber, take out the sheet and cool it;

[0117] 4) Fourth-stage mixing: Add the third-stage mixed rubber, sulfur, vulcanization accelerator, and scorch retarder, apply pressure with the upper plug for 30S, lift the plug for 10S, apply pressure for 30S, lift the plug for 10S, apply pressure for 30S, lift the plug for 10S, and then apply pressure for mixing for 100S or until it reaches 115°C, discharge the rubber, take out the sheet and cool it to obtain the said tread rubber composition.

[0118] Among them, the rotor speed: First-stage mixing: 45 rpm; Second-stage mixing: 50 rpm; Third-stage mixing: 50 rpm; Fourth-stage mixing: 20 rpm. The pressure of the upper plug: 102 bar; The pressure of the cooling water: ≥0.02 Mpa.

[0119] Example 4

[0120] In order to verify the optimization schemes in the above examples, in this example, the materials prepared in Examples 1-3 were subjected to performance testing. Specifically, the formulations of the tread rubber composition samples in Examples 1-3 are shown in Table 1.

[0121] Table 1 Formulation Table of Tread Rubber Composition

[0122]

[0123] By mixing the raw materials in the ratios shown in Table 1, the tread rubber composition samples in Examples 1-3 were obtained, and then performance testing was carried out, specifically including scorch time, rheological data (Re(151°C * 60 min%)), Payne Effect (ΔG' of unvulcanized rubber), bound rubber, Shore hardness, M100 modulus (100% modulus at elongation), M300 modulus (300% modulus at elongation), tensile strength, elongation at break, tanδ and E', and Lambourn abrasion. The performance test data obtained are shown in Table 2.

[0124] Table 2 Performance Test Results Table of Tread Rubber Composition

[0125]

[0126] It can be seen from the data in Table 2 that compared with Example 2, the processing performance of Example 3 is equivalent. The hysteresis loss (60°C - Tanδ) is reduced by 14%, but the stiffness of the rubber compound (5% - E') is increased by 8%, the deformation of the rubber compound is smaller, and the rolling resistance of the tire can be effectively reduced. The dosage of small molecules is reduced, and the abrasion performance is improved by 9%.

[0127] Compared with the reference formulation presented in Example 1, Example 3 shows a significant decrease in the Payne effect, indicating better filler dispersion performance. The physical and mechanical properties of the rubber compound are significantly improved, which is beneficial for ensuring the appearance of the tire during use, such as bottom groove cracks, cutting and chipping, etc. The hysteresis loss (60°C - Tanδ) is reduced by 32%, which can effectively reduce the rolling resistance of the tire. The amount of small molecules used is reduced, the rigidity E' is increased, and the abrasion resistance is improved by 25%.

[0128] In the prior art, the rubber composition containing solution styrene-butadiene rubber and other materials provided by the Chinese patent with the publication number CN101792545A has a Tanδ at 60°C ranging from 0.11 to 0.14. Among them, solution styrene-butadiene rubber is mainly used and a small amount of natural rubber or cis-butadiene rubber, highly dispersed silica, carbon black are used, and a silane coupling agent is used in the formulation. The vulcanization system needs to be adjusted according to the amount of silica used. In fact, it still uses too much silica. Only through a new material of Nanoprene rubber gel from LANXESS Company in Germany, the hysteresis loss of the tread compound can be further reduced by 16% on the original basis. However, for the tread rubber composition of the present invention, the Tanδ at 60°C can reach 0.07, showing obvious advantages.

[0129] Specifically, in order to improve the processing performance and rubber compound properties of the reference formulation, Example 2 uses 195GR silica as the raw material, and modifies the surface of silica (silicon dioxide) by atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP), so that a certain molecular weight of polymethyl methacrylate and polycaprolactone are grafted on its surface, forming a polymer brush with silica as the core, presenting strong hydrophobicity, so as to increase the compatibility between silica and the organic matrix. In this way, the agglomeration effect between silicas can be greatly reduced, the physical and mechanical properties of the rubber compound can be improved, and the heat generation can be reduced, and the rolling resistance of the tire can be reduced. At the same time, the silanization reaction of silica is completed in advance, Si-69, Rhein 37, and PEG3350 can be removed from the system, and the rubber compound mixing does not need to be heat-insulated, improving the mixing efficiency. At the same time, due to the significant optimization of the rubber compound processing performance, the usage amount of processing oil can also be reduced, which can further improve the physical and mechanical properties and abrasion resistance of the rubber compound, reduce the heat generation of the rubber compound, increase the rigidity E', and reduce the rolling resistance of the tire.

[0130] In summary, according to the analysis of test data, Example 3 can improve the physical and mechanical properties and abrasion resistance while reducing the heat generation of the rubber compound and increasing the rigidity, thereby reducing the rolling resistance of the tire, and the properties of the vulcanized rubber remain excellent. It solves the problem that in the existing low-rolling-resistance tread formulation, the amount of silica increases. Due to the large number of silanol groups on the surface of silica, it shows hydrophilicity, and it is very easy to cause agglomeration after the silanization reaction is not fully carried out, resulting in poor filler dispersion of the rubber compound, thus affecting the appearance of the semi-finished product extrusion and the abrasion and rolling resistance of the finished tire.

[0131] Example 5

[0132] To further verify the effects of the tread rubber composition samples in the above examples when actually applied to tire production, the above tread rubber composition samples will be used as tire tread materials to prepare finished tires below. The specific process refers to the prior art and will not be elaborated here. According to the "Technical Specification for 315 / 70R22.5 154 / 150L Standard Test Tires", the rolling resistance (abbreviated as rolling resistance) mainly refers to the elastic hysteresis loss caused by the deformation of the tire when the vehicle is running. By testing the rolling resistance of the finished tires, the rolling resistance test results of the finished tires are obtained, as shown in Table 3 specifically.

[0133] Table 3 Rolling Resistance Test Results of Finished Tires

[0134]

[0135] As can be seen from the data in Table 3, compared with the reference formula of Example 1 and Example 2, the rolling resistance of the tire in Example 3 decreased significantly. By replacing silica with modified silica, agglomeration is not easily caused, avoiding affecting the appearance of the semi-finished product during extrusion and the wear and rolling resistance of the finished tire.

[0136] Example 6

[0137] This example provides a tread rubber composition, including the following raw materials: 60 parts by weight of natural rubber; 40 parts by weight of solution styrene-butadiene rubber SLR3402; 50 parts by weight of silica 195GR; 4 parts by weight of Si-69; 2 parts by weight of TDAE (environmentally friendly aromatic oil); 1 part by weight of Rhein 37 (specifically using Lanxess chemical processing aid Aflux 37); 1 part by weight of polyethylene glycol PEG3350; 2 parts by weight of zinc oxide; 1 part by weight of stearic acid; 1 part by weight of antioxidant 4020; 0.5 part by weight of antioxidant RD; 1.2 parts by weight of ordinary sulfur; 1.4 parts by weight of vulcanization accelerator TBBS; 0.4 part by weight of scorch retarder CTP.

[0138] In this example, the preparation methods of the modified silica and the tread rubber composition both refer to Example 2 and will not be elaborated here.

[0139] Example 7

[0140] This embodiment provides a tread rubber composition, comprising the following raw materials: 80 parts by weight of natural rubber; 20 parts by weight of solution styrene-butadiene rubber SLR3402; 60 parts by weight of silica 195GR; 7 parts by weight of Si-69; 8 parts by weight of TDAE (environmentally friendly aromatic oil); 3 parts by weight of Rhein 37 (specifically using Lanxess chemical processing aid Aflux 37); 3 parts by weight of polyethylene glycol PEG3350; 5 parts by weight of zinc oxide; 3 parts by weight of stearic acid; 3 parts by weight of antioxidant 4020; 1.5 parts by weight of antioxidant RD; 1.4 parts by weight of ordinary sulfur; 1.6 parts by weight of vulcanization accelerator TBBS; 0.6 parts by weight of scorch retarder CTP.

[0141] In this embodiment, the preparation methods of the modified silica and the tread rubber composition both refer to Embodiment 2, and will not be elaborated here.

[0142] Example 8

[0143] This embodiment provides a tread rubber composition, comprising the following raw materials: 60 parts by weight of natural rubber; 40 parts by weight of solution styrene-butadiene rubber SLR3402; 50 parts by weight of modified silica; 2 parts by weight of TDAE (environmentally friendly aromatic oil); 1 part by weight of Rhein 37 (specifically using Lanxess chemical processing aid Aflux 37); 1 part by weight of polyethylene glycol PEG3350; 2 parts by weight of zinc oxide; 1 part by weight of stearic acid; 1 part by weight of antioxidant 4020; 0.5 part by weight of antioxidant RD; 1.2 parts by weight of ordinary sulfur; 1.4 parts by weight of vulcanization accelerator TBBS; 0.4 parts by weight of scorch retarder CTP.

[0144] In this embodiment, the preparation methods of the modified silica and the tread rubber composition both refer to Embodiment 3, and will not be elaborated here.

[0145] Example 9

[0146] This embodiment provides a tread rubber composition, comprising the following raw materials: 80 parts by weight of natural rubber; 20 parts by weight of solution styrene-butadiene rubber SLR3402; 60 parts by weight of modified silica; 8 parts by weight of TDAE (environmentally friendly aromatic oil); 3 parts by weight of Rhein 37 (specifically using Lanxess chemical processing aid Aflux 37); 3 parts by weight of polyethylene glycol PEG3350; 5 parts by weight of zinc oxide; 3 parts by weight of stearic acid; 3 parts by weight of antioxidant 4020; 1.5 parts by weight of antioxidant RD; 1.4 parts by weight of ordinary sulfur; 1.6 parts by weight of vulcanization accelerator TBBS; 0.6 parts by weight of scorch retarder CTP.

[0147] In this embodiment, the preparation methods of the modified silica and the tread rubber composition both refer to Embodiment 3, and will not be elaborated here.

[0148] Example 10

[0149] This embodiment provides a tread rubber composition, comprising the following raw materials: 60 parts by weight of natural rubber; 40 parts by weight of solution styrene-butadiene rubber SLR3402; 50 parts by weight of modified silica; 2 parts by weight of zinc oxide; 1 part by weight of stearic acid; 1 part by weight of antioxidant 4020; 0.5 part by weight of antioxidant RD; 1.2 parts by weight of ordinary sulfur; 1.4 parts by weight of vulcanization accelerator TBBS; 0.4 part by weight of scorch retarder CTP.

[0150] In this embodiment, the preparation method of the modified silica and the tread rubber composition both refer to Embodiment 3, and will not be elaborated here.

[0151] Example 11

[0152] This embodiment provides a tread rubber composition, comprising the following raw materials: 80 parts by weight of natural rubber; 20 parts by weight of solution styrene-butadiene rubber SLR3402; 60 parts by weight of modified silica; 5 parts by weight of zinc oxide; 3 parts by weight of stearic acid; 3 parts by weight of antioxidant 4020; 1.5 parts by weight of antioxidant RD; 1.4 parts by weight of ordinary sulfur; 1.6 parts by weight of vulcanization accelerator TBBS; 0.6 part by weight of scorch retarder CTP.

[0153] In this embodiment, the preparation method of the modified silica and the tread rubber composition both refer to Embodiment 3, and will not be elaborated here.

[0154] Example 12

[0155] Compared with Embodiment 3, except that the specific parameter values in the preparation method of the tread rubber composition are different, other aspects are the same as those in Embodiment 3.

[0156] In this embodiment, the preparation method of the tread rubber composition specifically comprises the following steps:

[0157] 1) First-stage mixing: Add all materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica, apply pressure with the upper plug for 20 s, lift the plug and add 50% of the modified silica, apply pressure with the upper plug for 25 s, lift the plug and add the remaining 20% of the modified silica, apply pressure with the upper plug for 25 s, lift the plug for 5 s, and then apply pressure for mixing for 120 s or until 150 °C, discharge the rubber, take out the sheet and cool it;

[0158] 2) Second-stage mixing: Add the first-stage mixed rubber, apply pressure with the upper plug for 30 s, lift the plug for 5 s, and apply pressure for mixing for 100 s or until 150 °C, discharge the rubber, take out the sheet and cool it;

[0159] 3) Third-stage mixing: Add the second-stage mixed rubber, apply pressure with the upper plug for 30 s, lift the plug for 5 s, and apply pressure for mixing for 100 s or until 150 °C, discharge the rubber, take out the sheet and cool it;

[0160] 4) Fourth-stage mixing: Add the third-stage mixed rubber, sulfur, vulcanization accelerator, and scorch retarder, apply pressure with the upper plug for 20S, lift the plug for 5S, apply pressure for 20S, lift the plug for 5S, apply pressure for 20S, lift the plug for 5S, and then apply pressure for mixing for 100S or until it reaches 105°C, discharge the rubber, sheet it out and cool it to obtain the said tread rubber composition.

[0161] Among them, the rotor speed: First-stage mixing: 35 rpm; Second-stage mixing: 40 rpm; Third-stage mixing: 40 rpm; Fourth-stage mixing: 15 rpm. The pressure of the upper plug: 85 bar; The pressure of the cooling water: ≥0.01 Mpa.

[0162] Example 13

[0163] Compared with Example 3, except for the different specific parameter values in the preparation method of the tread rubber composition, the others are the same as those in Example 3.

[0164] In this example, the preparation method of the said tread rubber composition specifically includes the following steps:

[0165] 1) First-stage mixing: Add all materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica, apply pressure with the upper plug for 40S, lift the plug and add 80% of the modified silica, apply pressure with the upper plug for 45S, lift the plug and add the remaining 50% of the modified silica, apply pressure with the upper plug for 45S, lift the plug for 15S, and then apply pressure for mixing for 120S or until it reaches 160°C to discharge the rubber, sheet it out and cool it;

[0166] 2) Second-stage mixing: Add the first-stage mixed rubber, apply pressure with the upper plug for 60S, lift the plug for 15S, apply pressure for mixing for 100S or until it reaches 160°C to discharge the rubber, sheet it out and cool it;

[0167] 3) Third-stage mixing: Add the second-stage mixed rubber, apply pressure with the upper plug for 60S, lift the plug for 15S, apply pressure for mixing for 100S or until it reaches 160°C to discharge the rubber, sheet it out and cool it;

[0168] 4) Fourth-stage mixing: Add the third-stage mixed rubber, sulfur, vulcanization accelerator, and scorch retarder, apply pressure with the upper plug for 40S, lift the plug for 15S, apply pressure for 40S, lift the plug for 15S, apply pressure for 40S, lift the plug for 15S, and then apply pressure for mixing for 100S or until it reaches 125°C to discharge the rubber, sheet it out and cool it to obtain the said tread rubber composition.

[0169] Among them, the rotor speed: First-stage mixing: 55 rpm; Second-stage mixing: 55 rpm; Third-stage mixing: 55 rpm; Fourth-stage mixing: 30 rpm. The pressure of the upper plug: 125 bar; The pressure of the cooling water: ≥0.02 Mpa.

[0170] Example 14

[0171] Compared with Example 3, except that 3.504 parts of the ATRP reaction catalyst 2,2'-bipyridine was replaced with 1.386 parts of the ATRP reaction catalyst pentamethyldiethylenetriamine (PMDETA), the others were the same as in Example 3.

[0172] Example 15

[0173] Taking the formulation of Example 1 as the reference formulation, the proportion of the parts of natural rubber and solution styrene-butadiene rubber SLR3402 in the formulation of Example 1 was adjusted to obtain the tread rubber composition formulations of Comparative Example 1 and Comparative Example 2. Taking the formulation of Comparative Example 1 as the reference, silica 195GR was replaced with SiO2-g-PMMA / PCL, and the processing oil and small molecules used for the silanization reaction were removed to obtain Improvement Example 1; taking the formulation of Comparative Example 2 as the reference, silica 195GR was replaced with SiO2-g-PMMA / PCL, and the processing oil and small molecules used for the silanization reaction were removed to obtain Improvement Example 2. The specific formulation ratios are shown in Table 4. Among them, the numbers in parentheses in Table 4 are the raw material ratio ranges, and the numbers outside the parentheses are the preferred ratio values. For example, the dosage of natural rubber in Comparative Example 1 is 80 (70-90), which means that the dosage range of natural rubber in Comparative Example 1 is 70-90 parts, and the preferred is 80 parts; also, for example, the dosage of solution styrene-butadiene rubber SLR3402 in Comparative Example 1 is 10-30 parts, and the preferred is 20 parts, and so on. It should be noted that the total dosage of natural rubber and solution styrene-butadiene rubber SLR3402 is 100 parts.

[0174] Table 4 Different Formulation Ratios

[0175]

[0176] It should be noted that in the 1970s, it was found that when silica was used in combination with a silane coupling agent, it had the effect of improving the wet grip of tires and reducing the rolling resistance of tires. In recent years, with the upgrading of the EU tire labeling law and the proposal of the carbon neutrality goal, it is a trend that the usage amount of silica gradually increases. Ordinary tires have gradually lost their competitive advantages, and the development and application of low rolling resistance tire products will become the mainstream trend.

[0177] In this embodiment, SiO2-g-PMMA / PCL is the modified silica prepared in Example 3. By replacing 195GR silica with SiO2-g-PMMA / PCL and removing the processing oil and small molecules used in the silanization reaction, a modified silica-filled low rolling resistance tread rubber composition is provided, which is mainly applied to all-steel radial truck tires. Compared with the traditional low rolling resistance tread formula, the filler dispersion, abrasion resistance, and physical and mechanical properties of this tread formula are better. At the same time, it can reduce the hysteresis loss, thereby reducing the rolling resistance of the tire. Moreover, a modification method of this kind of silica and a kneading method of the formula in a kneader are also provided to ensure the dispersion performance of the rubber compound. Taking Improvement Example 2 as an example, since the silica in the formula has been surface-modified in advance, the use of the silane coupling agent Si-69 is removed from the formula system.

[0178] Performance testing

[0179] The tread rubber compositions of Comparative Ratio 1 and Comparative Ratio 2 in Example 15 and the tread rubber compositions in Improvement Example 1 and Improvement Example 2 were subjected to performance tests, and the specific results are shown in Table 5.

[0180] Table 5 Summary of performance test results

[0181]

[0182]

[0183] It can be seen from the data in Table 5 that the Payne effect of the tread rubber compositions prepared from the formula of Improvement Example 1 compared with Comparative Ratio 1 and the formula of Improvement Example 2 compared with Comparative Ratio 2 both decreased significantly, indicating better filler dispersion performance, significant improvement in the physical and mechanical properties of the rubber compound, significant reduction in the hysteresis loss (60°C - Tanδ), and a large improvement in the abrasion resistance. In terms of data testing, a small hysteresis loss of the tread material measured at 60°C means a low rolling resistance of the tire (better performance). The hysteresis losses of the tread rubber compound tested at 0°C and 20°C represent the wet and dry road surface grip performances respectively, which are opposite to the influence of the 60°C temperature. The greater the hysteresis loss at 0°C, the better the wet skid resistance of the tire (better tire performance).

[0184] Combined with the experimental data of other embodiments above, it can be shown that the modified silica SiO2-g-PMMA / PCL can be applied to different formula systems, with significant improvements in filler dispersion, physical and mechanical properties, and abrasion resistance, and a significant reduction in heat generation. Thus, due to the early completion of the coupling reaction of the modified silica, the first-stage kneading time of the tread rubber composition in Example 3 is greatly shortened during preparation, improving the kneading efficiency and reducing the manufacturing energy consumption.

[0185] It should be noted that in the prior art, styrene-butadiene rubber is commonly used in low rolling resistance and high wet grip tread formulations. However, the strength of styrene-butadiene rubber is lower than that of natural rubber, and the binding ability between styrene-butadiene rubber and silica is restricted by many factors. Although the prior art methods can reduce the hysteresis loss of the rubber compound by increasing the amount of silica, when the amount of silica is large, agglomeration between particles is likely to occur when the silanization reaction is insufficient, resulting in poor filler dispersion performance, difficult processing of the rubber compound, and affecting the heat generation performance and physical and mechanical properties of the rubber compound. Specifically, in view of the design characteristics of the low rolling resistance tread formulation, the amount of carbon black is reduced and the amount of silica is increased. Due to the large number of silanol groups on the surface of silica, it shows hydrophilicity, and it is extremely easy to cause agglomeration after the silanization reaction is not sufficient, resulting in poor filler dispersion of the rubber compound, thereby affecting the appearance of the semi-finished extruded product and the abrasion and rolling resistance of the finished tire.

[0186] The present invention provides a low rolling resistance tire tread rubber composition with low hysteresis loss, high rigidity, and excellent physical and mechanical properties, and a preparation method thereof. By using silica 195GR as the raw material, a polymer brush is grafted on the surface of silica to make its surface hydrophobic, greatly enhancing the compatibility with rubber, and the use of processing oil can be removed. At the same time, the silanization reaction is completed in advance, and there is no need to add silane coupling agent and other small molecules that supplement the silanization reaction during the rubber compound mixing process, and the physical and mechanical properties and abrasion performance of the rubber compound can also be improved. That is, the present invention provides a low rolling resistance tire tread rubber composition with low hysteresis loss, high rigidity, excellent physical and mechanical properties, and good processing performance, and a preparation method thereof.

[0187] From the above results, it can be seen that the beneficial effects of the embodiments of the present invention are as follows. The embodiments of the present invention provide a modified silica-filled tread rubber composition through the reasonable use of natural rubber, solution-polymerized styrene-butadiene rubber, modified silica, sulfur, vulcanization accelerator, scorch retarder, and an appropriate amount of anti-aging agent, which can optimize the filler dispersion, reduce the use of small molecules at the same time, improve the abrasion and physical and mechanical properties of the tire, and reduce the rolling resistance of the tire, solving the problem that the method of increasing the amount of silica to reduce the rolling resistance of the tire in the prior art is likely to cause poor filler dispersion performance of the rubber compound. Moreover, the provided tread rubber composition and its internal mixer mixing preparation method can be used to prepare other types of rubber compositions, and have broad market prospects.

[0188] It should be noted that in the above embodiments of the present invention, for the performance detection of the samples, the measurement conditions and standards are as follows:

[0189] 1. Scorch time: According to GB / T 1233-2008, measure the scorch time of the rubber specimen sheet at 127 °C to obtain the detection data corresponding to the scorch time MS127 °C t3 (min).

[0190] 2. Rheological data: According to GB / T 16584-1996, the rheological data were measured using an MDR2000 non-rotor vulcanizer from ALPHA Company, USA, under the test conditions of 151 °C and 60 minutes. The vulcanization reversion rate was calculated according to the following formula: Vulcanization reversion rate = (Ffinal - FL) / (Fmax - FL), where Ffinal is the torque or force at the end of the test, in N·m or N; Fmax is the maximum torque or force during the test, in N·m or N; and FL is the minimum torque or force, in N·m or N.

[0191] 3. Payne Effect: According to ASTM D6204, ΔG' of the unvulcanized rubber was tested.

[0192] 4. Bound rubber: According to the enterprise standard TC-10-02-282, about 0.5 g of the mixed rubber was weighed, and its mass W1 was recorded. It was cut into small pieces about 1 mm 3 in size. First, the mixed rubber was wrapped with a nickel mesh with a mass of W2 that had been pre-dried in a vacuum oven at 35 °C, placed in a beaker, 100 ml of toluene was added to the beaker, and the mouth of the beaker was sealed with a sealing film to prevent solvent volatilization. It was soaked at room temperature for 48 h, and then the solvent was replaced and soaked for another 24 h. The filter mesh was taken out, dried at room temperature for several hours, and then dried to a constant weight at 35 °C in a vacuum oven, with a mass of W3. It was calculated according to the following formula: Bound rubber = (W3 - W2 - W1 × mass fraction of filler in the mixed rubber) / (W1 × mass fraction of rubber in the mixed rubber) × 100%.

[0193] 5. Shore hardness: According to GB / T 531.1-2008, the Shore hardness of the rubber specimen sheet was measured at 25 °C.

[0194] 6. M100 modulus (100% modulus at elongation), M300 modulus (300% modulus at elongation), tensile strength, and elongation at break were measured according to GB / T 528-2009 (using a rubber specimen sheet with a dumbbell type 1 shape).

[0195] 7. tanδ and E': According to ISO 4664-1:2005, a rubber specimen sheet with a thickness of 2 mm was tested at an initial strain of 10%, a dynamic strain of 5%, and a frequency of 10 Hz. The loss tangent tanδ and stiffness E' of the rubber specimen sheet were measured using a dynamic mechanical analyzer (DMA) model GABOMETER 2000 manufactured by GABO Company, Germany. Among them, tanδ at 60 °C (i.e., the detection data corresponding to 60 °C-Tanδ) is related to the heat generation performance of the rubber. The smaller the value of tanδ at 60 °C, the lower the heat generation; E' characterizes the stiffness of the rubber. The larger the value of E' at 60 °C (i.e., the detection data corresponding to 5%-E'), the smaller the deformation of the rubber under the same conditions.

[0196] 8. Lambourn Abrasion: In accordance with ISO 23337-2016, an AB-1152 type Lambourn tester from Ueshima Company is used. The input parameters are as follows: the applied force F = 40 N to simulate the load of the tire; the linear speed of the abrasion wheel is 80 m / min, the slip rate is set at slip 30%, and the linear speed of the specimen wheel is 56 m / min. Weigh the specimen wheel before operation and weigh it again after running for 48 s, and convert the worn volume according to the density. Taking the abrasion performance of the reference formula as 100, convert the abrasion performance of the improved examples into an index. The higher the index, the better the abrasion performance.

[0197] The above has described in detail the preferred embodiments of the present invention. However, the embodiments of the present invention are not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the embodiments of the present invention. It is not necessary and impossible to enumerate all the embodiments here. And the obvious changes or variations derived therefrom are still within the protection scope of the embodiments of the present invention.

Claims

1. A tread rubber composition, characterized in that, The tread rubber composition comprises the following raw materials: natural rubber, solution styrene-butadiene rubber, modified silica, sulfur, vulcanization accelerator, scorch retarder, and an appropriate amount of antioxidant; wherein, the modified silica is obtained by adding silica into a silane coupling agent solution for heating reaction, placing the product after the heating reaction in tetrahydrofuran, adding an excessive amount of glycidyl chloro-isobutyrate, heating, filtering, washing, drying, and then adding cuprous chloride, methyl methacrylate monomer, atom transfer radical polymerization catalyst, ε-caprolactone monomer, stannous octoate under nitrogen protection and carrying out stirring polymerization at 80-100 °C; The silane coupling agent solution comprises the following raw materials by weight parts: 10-30 parts of silane coupling agent, 65-75 parts of ethanol, and 5-10 parts of water; when preparing the modified silica, the raw materials added in the stirring polymerization include, by weight parts: 0.8-1.2 parts of cuprous chloride, 500-600 parts of methyl methacrylate monomer, 1-4 parts of atom transfer radical polymerization catalyst, 900-1100 parts of ε-caprolactone monomer, and 5-10 parts of stannous octoate; The raw material used for the modified silica is 195GR silica with a BET adsorption specific surface area of 180 - 220 m 2 / g, and the silane coupling agent used is silane coupling agent Si-69.

2. The tread rubber composition according to claim 1, characterized in that, The atom transfer radical polymerization catalyst is selected from any one of pentamethyldiethylenetriamine or 2,2'-bipyridine.

3. The tread rubber composition according to claim 1, characterized in that, The tread rubber composition comprises the following raw materials by weight parts: 60-80 parts of natural rubber; 20-40 parts of solution styrene-butadiene rubber; 50-60 parts of modified silica; 1.2-1.6 parts of sulfur; 1.4-1.8 parts of vulcanization accelerator; 0-5 parts of antioxidant; 0.2-0.8 parts of scorch retarder.

4. The tread rubber composition according to claim 3, characterized in that, The tread rubber composition comprises the following raw materials by weight parts: 60-80 parts of natural rubber; 20-40 parts of solution styrene-butadiene rubber; 50-60 parts of modified silica; 0-8 parts of environmental aromatic oil; 0-3 parts of polyethylene glycol; 0-3 parts of Rhein 37; 2-5 parts of zinc oxide; 1-3 parts of stearic acid; 1-5 parts of antioxidant; 1.2-1.4 parts of sulfur; 1.4-1.6 parts of vulcanization accelerator; 0.4-0.6 parts of scorch retarder.

5. The tread rubber composition according to claim 1, characterized in that, The solution styrene-butadiene rubber has a styrene content of 12%-18% and a vinyl content of 25%-35%.

6. A method for preparing a tread rubber composition as described in any one of claims 1 - 5, characterized in that, It includes the following steps: 1) Add all the raw materials except sulfur, vulcanization accelerator, scorch retarder, and modified silica into a mixer according to the proportion, add the modified silica after pressurization for mixing, and then carry out pressurized mixing until the temperature reaches 150 °C - 160 °C, then discharge the rubber, take out the sheet and cool it to obtain the first-stage mixed rubber; 2) Subject the first-stage mixed rubber to multiple pressurized mixing, then add sulfur, vulcanization accelerator, and scorch retarder, after multiple pressurizations of the upper plug and decompressions of the plug, carry out pressurized mixing until the temperature reaches 105 °C - 125 °C, discharge the rubber, take out the sheet and cool it to obtain the tread rubber composition.

7. A tread rubber composition prepared by using the method for preparing a tread rubber composition as described in claim 6.

8. An application of the tread rubber composition as described in claim 1 or 2 or 3 or 4 or 5 in the preparation of a tire.

Images