Electric vehicle tire tread rubber composition containing thiophenol lignin hybrid material and mixing method thereof

Abstract

The invention relates to the technical field of tire rubber manufacturing, and discloses an electric vehicle tire tread rubber composition containing a thiophenol lignin hybrid material and a mixing method of the electric vehicle tire tread rubber composition, and the thiophenol lignin hybrid material is added into the rubber composition. The thiophenol lignin hybrid material is a hydrophobic thiophenol material obtained through reaction modification of lignin and sulfur, can be directly applied to traditional dry-method mixing, effectively improves the dispersity of lignin in rubber, improves the mechanical property and stability of a rubber material, reduces rolling resistance, realizes effective replacement of carbon black, and is simple in process, convenient to operate, convenient, fast and efficient. And large-scale industrial production can be realized more easily.

Description

Technical Field

[0001] This invention relates to the field of tire rubber manufacturing technology, and in particular to a tread rubber composition for electric vehicle tires containing sulfur-containing phenol-lignin hybrid materials and its mixing method. Background Technology

[0002] With the increasing demand for lightweighting and maximizing the range of electric vehicles, the corresponding tires also require technological upgrades. Lightweighting of electric vehicle tires can be achieved by reducing tire weight and rolling resistance. However, the "magic triangle" of rolling resistance, wet skid resistance, and wear resistance in rubber tire use makes materials the biggest limitation to lightweighting. With the rapid development of the global tire industry, focusing on high-performance, functional, and differentiated products, especially under the major trend of green environmental protection, the rubber compounds and traditional additives used in tire manufacturing are gradually being replaced by some eco-friendly new materials. The use of various bio-based matrix rubbers, bio-based reinforcing materials, and bio-based additives has enabled tires to possess both good load-bearing and cushioning performance, as well as high wear resistance, wet skid resistance, and low rolling resistance, making it a hot topic and focus of research and application.

[0003] Lignin is the second most abundant biomass resource in the plant kingdom, after cellulose. Globally, the annual natural production of lignin reaches 100-150 million tons, while industrial extraction is approximately 50 million tons per year. Most of this is incinerated or discharged as waste, severely polluting the environment. Lignin molecules contain various functional groups, enabling them to undergo a wide range of chemical reactions. Currently, finding new fillers to replace carbon black for reinforcing rubber is a trend in social development, and lignin, being inexpensive and environmentally friendly, has become the ideal alternative. Therefore, strengthening the development and utilization of lignin is a major trend in contemporary social progress.

[0004] Chinese invention patent (publication number: CN119875211A, publication date: 2025-04-25) discloses a rubber composition containing modified lignin and its mixing method, wherein modified lignin is added to the rubber composition. The modified lignin is a water-soluble lignin obtained by grafting citric acid groups onto lignin. By modifying lignin with citric acid and grafting citric acid groups onto the lignin groups under the catalysis of sodium hypophosphite to enhance its hydrophilicity, combined with wet mixing, the dispersibility of lignin in the rubber is effectively improved, the rolling resistance of the rubber composition is reduced, and the addition of lignin can enhance the rubber network strength and improve the tensile properties of the rubber.

[0005] Chinese invention patent (publication number: CN120098339A, publication date: 2025-06-06) discloses a tread rubber composition containing modified lignin and its mixing method, wherein modified lignin is added to the rubber composition. The modified lignin is a water-soluble lignin obtained by grafting citric acid groups onto lignin. By modifying lignin with citric acid and grafting citric acid groups onto the lignin groups under the catalysis of sodium hypophosphite to enhance its hydrophilicity, combined with wet mixing, the dispersibility of lignin in the rubber is effectively improved, the rolling resistance of the rubber composition is reduced, and the addition of lignin can enhance the rubber network strength and improve the tensile properties of the rubber.

[0006] Rubber, due to its compact molecular structure, exhibits good hydrophobicity. Hydrophobic fillers can effectively improve its dispersibility in rubber products, further enhancing the mechanical properties and water resistance of rubber products and extending their service life. The phenolic hydroxyl groups in lignin have strong reactivity and can react with the double bonds in rubber molecules, forming a cross-linked network structure between rubber molecules. These cross-linking points can prevent the slippage and relative displacement of rubber molecular chains, thereby improving the physical properties of rubber. Sulfur also has similar chemical reactivity; it can open the double bonds in rubber molecules and form covalent bonds with rubber molecular chains, thus constructing a cross-linked network structure between rubber molecules. Utilizing the high-temperature ring-opening property of sulfur, it reacts with the phenolic hydroxyl groups of lignin under alkaline conditions. Sulfur atoms replace the oxygen atoms of the phenolic hydroxyl groups, enhancing the overall hydrophobicity. Simultaneously, the resulting thiophenol-lignin hybrid material contains a large number of sulfur atoms and phenolic hydroxyl groups, increasing the number of reactive sites, promoting the dispersion of lignin in the rubber matrix, and significantly increasing the degree of vulcanization and physical properties of the rubber composition.

[0007] Furthermore, the wet mixing process, which directly mixes lignin with a significant proportion of moisture into rubber, while achieving good dispersion, also creates problems for the rubber mixing process. For example, it requires long-term storage to remove residual moisture, making it difficult to promote in large-scale rubber product production. Simultaneously, this process reduces the hardness, tensile strength, and tear hardness of the rubber compound, affecting the crystallization stability of natural rubber. In contrast, the dry mixing process directly adds lignin to rubber to enhance its properties. This process is simple, convenient, efficient, and easily scalable for large-scale industrial production. If the dispersibility of lignin in rubber can be improved, the advantages of dry mixing will be even more significant. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an electric vehicle tire tread rubber composition containing thiophenol lignin hybrid material and its mixing method. The thiophenol lignin hybrid material used in this tread can effectively replace carbon black in the preparation of the tread rubber composition, and can improve the dispersibility of lignin in rubber in traditional dry mixing.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] This invention provides a tread rubber composition for electric vehicle tires containing a sulfur-phenol lignin hybrid material. The rubber composition is prepared by dry mixing and is derived from raw materials comprising the following components per 100 parts by weight of raw rubber:

[0011] Natural rubber: 45.0-55.0 parts, styrene-butadiene rubber: 22.0-25.0 parts, butadiene rubber: 20.0-30.0 parts, carbon black: 55.0-95.0 parts, thiophenol lignin hybrid material: 8.0-18.0 parts, white oil: 5.0-9.0 parts, antioxidant: 1.0-5.0 parts, activator: 1.0-8.0 parts, coupling agent: 1.5-2.5 parts, paraffin wax: 2.0-4.5 parts, scorching inhibitor: 0.1-0.5 parts, accelerator: 1.0-2.0 parts, vulcanizing agent: 1.0-2.5 parts.

[0012] Preferably, the thiophenol-lignin hybrid material is a hydrophobic thiophenol material containing a large number of sulfur atoms and phenolic hydroxyl groups, obtained by fully reacting lignin with sulfur under alkaline conditions of sodium carboxylate.

[0013] Preferably, the preparation method of the thiophenol-lignin hybrid material includes the following steps:

[0014] 1) At room temperature, lignin, sulfur, and sodium carboxylate are thoroughly ground and mixed and placed in a hydrothermal reactor. Deionized water with pH=12 is then added and stirred to mix the solution evenly. The reaction conditions are adjusted to 80-200℃ and the reaction is continuously stirred for 6.0-48.0h.

[0015] 2) After the reaction is complete, the suspension is stirred and dissolved in an alkaline aqueous solution with pH=8-12 for 0.5-1.5h, and then filtered to separate, yielding a dark black liquid.

[0016] 3) Slowly add hydrochloric acid to the dark black liquid and adjust the pH to 2-6 until no more precipitate forms. Thiophene-lignin hybrid nanoparticles are obtained by centrifugation purification. The precipitate of thiophenol-lignin hybrid nanoparticles obtained after centrifugation is dialyzed in deionized water. The suspension of thiophenol-lignin hybrid nanoparticles is diluted to below 1%, and then ultrasonically treated to ensure uniform dispersion in deionized water.

[0017] 4) Freeze-drying to obtain thiophenol-lignin hybrid materials.

[0018] Preferably, the weight ratio of lignin to sulfur is 1:0.2-20; And / or, the weight ratio of the lignin to sodium carboxylate is 1:0.001-0.2; And / or, the freeze-drying temperature is -45°C to -55°C, and the vacuum degree is 0.10-0.13 mbar.

[0019] Preferably, the dry mixing process includes the following steps:

[0020] 1) First stage mixing: Rubber, carbon black, activator, antioxidant, white oil and paraffin are mixed, discharged, sheeted and left to stand to obtain the initial masterbatch;

[0021] 2) Two-stage mixing: The thiophenol-lignin hybrid material, coupling agent and initial masterbatch are mixed, discharged, sheeted and left to stand to obtain the compounded rubber;

[0022] 3) Three-stage mixing: Mix the compound rubber, anti-scorching agent, accelerator and vulcanizing agent, discharge the rubber, sheet it, and let it stand to obtain the final rubber.

[0023] Preferably, the carbon black has a particle size of 20-60 nm.

[0024] Preferably, the antioxidant is antioxidant 4020 and / or antioxidant RD, and / or antioxidant 4010NA, wherein antioxidant 4020 is 0.5-4.0 parts, antioxidant RD is 0.5-2.0 parts, and antioxidant 4010NA is 0.5-1.5 parts.

[0025] Preferably, the activator is zinc oxide and stearic acid, with zinc oxide at 1.0-5.0 parts and stearic acid at 1.0-3.0 parts.

[0026] Preferably, the coupling agent is silane coupling agent SI-69.

[0027] Preferably, the accelerator is accelerator CZ and / or accelerator NS, wherein accelerator CZ is 1.0-1.5 parts and accelerator NS is 0.1-0.5 parts.

[0028] Furthermore, the present invention also discloses a method for mixing the electric vehicle tire tread rubber composition of the sulfur-containing phenol lignin hybrid material, which employs a dry mixing process and includes the following steps:

[0029] 1) First stage mixing: Mix using an internal mixer at a speed of 45 r / min; add rubber, press down and hold for 30 seconds; raise the press, add carbon black, activator and antioxidant, press down and hold for 30 seconds; raise the press, add white oil and paraffin wax, press down and hold for 40 seconds; raise the press, clean; press down and hold for 40 seconds; raise the press, discharge the rubber, sheet, and let stand to obtain the initial masterbatch.

[0030] 2) Two-stage mixing: Mixing is carried out using an internal mixer at a speed of 40 r / min; the initial masterbatch is added, and the compaction is held for 30 seconds; the compaction is raised, the mixing speed is adjusted to 30 r / min, the thiophenol lignin hybrid material and coupling agent are added, and the compaction is held for 60 seconds; the compaction is raised, and the compaction is held for 60 seconds; the compaction is raised, the glue is discharged, the sheets are cut, and the mixture is left to stand to obtain the compound.

[0031] 3) Three-stage mixing: Mixing is carried out using an internal mixer at a speed of 20 r / min; add the compound rubber, anti-scorching agent, accelerator, and vulcanizing agent, press down and hold for 30 seconds; raise the press down and hold for 40 seconds; raise the press down, discharge the rubber, sheet it, and let it stand to obtain the final compound rubber.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention modifies lignin with sulfur. By reacting with the phenolic hydroxyl groups of lignin, the resulting thiophenol-lignin hybrid material not only contains phenolic hydroxyl groups but also a large number of sulfur atoms, resulting in enhanced overall hydrophobicity and increased reactive sites. This promotes the dispersion of lignin in the rubber matrix, effectively replacing carbon black, and can be directly applied to traditional dry mixing. The process is simple, convenient, efficient, and easier to scale up for industrial production. The phenolic hydroxyl groups react with the double bonds in rubber molecules to form a cross-linked network structure between rubber molecules, preventing slippage and relative displacement of rubber molecular chains, significantly increasing the degree of vulcanization and physical properties of the rubber composition, and reducing the rolling resistance of the rubber composition. The thiophenol-lignin hybrid material contains a hindered phenolic structure, which can capture active free radicals generated by rubber molecular chains during rubber aging, effectively delaying the degradation and damage of rubber molecular chains and improving the stability of the rubber composition.

[0034] In the rubber composition of the present invention, in addition to the components described above, various additives may be mixed, such as other fillers commonly used in tires and other rubber compositions, vulcanizing agents, vulcanization accelerators, different types of oils, antioxidants, plasticizers, etc. These additives are mixed using conventional methods to obtain a rubber composition suitable for vulcanization. The amounts of these additives may also be conventional, typical mixing amounts, provided that this does not, in turn, affect the purpose of the present invention. Detailed Implementation

[0035] 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.

[0036] The formulations of the examples and comparative examples are shown in Table 1 (parts by weight).

[0037] Table 1

[0038] Main raw materials: *1: Natural rubber, Qingdao Ruitongcai International Trade Co., Ltd.; *2: Styrene-butadiene rubber 1712, Shandong Hualunte Trade Co., Ltd.; *3: Butadiene rubber BR9000, Shandong Hualunte Trade Co., Ltd.; *4: Carbon black N330, Shanxi Sanqiang New Energy Technology Co., Ltd.; *5: Carbon black N660, Shanxi Sanqiang New Energy Technology Co., Ltd.; *6: Lignin, Hangshi Technology Development Co., Ltd.; *7: White oil, Taian Kunqing Trade Co., Ltd.; *8: Antioxidant 4020, Shandong Shangshun Chemical Co., Ltd.; *9: Antioxidant RD, Shandong Shangshun Chemical Co., Ltd.; *10: Antioxidant 401 *11: Zinc oxide, Anqiu Hengshan Zinc Industry Co., Ltd.; *12: Stearic acid, Linqing Xingtai Rubber Additives Co., Ltd.; *13: Silane coupling agent SI-69, Dongying Lizhiyuan New Material Co., Ltd.; *14: Protective wax RW254, Jiangsu Ruiba New Material Technology Co., Ltd.; *15: Anti-scorching agent CTP, Henan Yongxin Chemical Co., Ltd.; *16: Accelerator CZ, Ningbo Aikem New Material Co., Ltd.; *17: Accelerator NS, Jiangsu Lianlian Chemical Co., Ltd.; *18: Sulfur masterbatch S-80, Taian De'an Chemical Technology Co., Ltd.

[0039] The comparative proportion uses dry mixing.

[0040] The specific steps of dry mixing are as follows:

[0041] 1) First stage of mixing: Mix using an internal mixer at a speed of 45 r / min; add rubber, press down and hold for 30 seconds; raise the press, add carbon black, activator, antioxidant and / or lignin, and / or coupling agent, press down and adjust the mixing speed to 30 r / min, hold for 60 seconds; raise the press, add white oil and paraffin wax, press down and hold for 70 seconds; raise the press, discharge the rubber, sheet it, and let it stand to obtain the mixed rubber.

[0042] 2) Two-stage mixing: Mixing is carried out using an internal mixer at a speed of 20 r / min; add the mixed rubber, press down and hold for 30 seconds; raise the press, add the accelerator, anti-scorching agent and vulcanizing agent, press down and hold for 40 seconds; raise the press, discharge the rubber, sheet it, and let it stand to obtain the final rubber.

[0043] The example uses dry mixing.

[0044] The specific steps of dry mixing are as follows:

[0045] 1) First stage mixing: Mixing is carried out using an internal mixer at a speed of 45 r / min; add rubber, press down and hold for 30 seconds; raise the press, add carbon black, activator and antioxidant, press down and hold for 30 seconds; raise the press, add white oil and paraffin wax, press down and hold for 40 seconds; raise the press, clean; press down and hold for 40 seconds; raise the press, discharge the rubber, sheet, and let stand to obtain the initial masterbatch.

[0046] 2) Two-stage mixing: Mixing is carried out using an internal mixer at a speed of 40 r / min; the initial masterbatch is added, and the compaction is held for 30 seconds; the compaction is raised, the mixing speed is adjusted to 30 r / min, the thiophenol lignin hybrid material and coupling agent are added, and the compaction is held for 60 seconds; the compaction is raised, and the compaction is held for 60 seconds; the compaction is raised, the glue is discharged, the sheets are cut, and the mixture is left to stand to obtain the compound.

[0047] 3) Three-stage mixing: Mixing is carried out using an internal mixer at a speed of 20 r / min; add the compound rubber, anti-scorching agent, accelerator, and vulcanizing agent, press down and hold for 30 seconds; raise the press down and hold for 40 seconds; raise the press down, discharge the rubber, sheet it, and let it stand to obtain the final compound rubber.

[0048] Physicochemical data analysis of the rubber compositions obtained in the above embodiments and comparative examples.

[0049] Main experimental equipment: MZ-4000D, Jiangsu Mingzhu tensile testing machine; GT-7080S2, Dongguan High-speed Railway Instrument Co., Ltd.; GT-M2000A, Dongguan High-speed Railway Instrument Co., Ltd.; DMA Q800, TA Instruments, USA.

[0050] The test data is shown in Table 2.

[0051] Table 2

[0052] Analysis of Table 2 shows that Example 2 is the best example, exhibiting the optimal overall performance. Comparative Examples 1 and 2, and Examples 1, 2, and 3, demonstrate that the addition of lignin or thiophenol-lignin hybrid materials increases the degree of crosslinking in the rubber composition and shortens T10 and T90. This is because the phenolic hydroxyl groups in the lignin or thiophenol-lignin hybrid materials promote vulcanization. The ozone resistance of the rubber composition is enhanced because the lignin or thiophenol-lignin hybrid materials contain hindered phenolic structures, which can capture active free radicals generated by the rubber molecular chains during rubber aging, effectively delaying the degradation and damage of the rubber molecular chains and improving the stability of the rubber composition. Comparative Examples 1 and 2 show that Example 2 exhibits significantly improved filler dispersibility, significantly improved rubber network strength, significantly enhanced tensile properties, and relatively low rolling resistance. The thiophenol-lignin hybrid material can effectively replace some carbon black. Comparative Example 2 and Example 2 show that modifying lignin with sulfur, through reaction with the phenolic hydroxyl groups of lignin, results in a thiophenol-lignin hybrid material containing not only phenolic hydroxyl groups but also a large number of sulfur atoms, increasing the number of reactive sites and effectively promoting the dispersion of lignin in the rubber matrix. Examples 1, 2, and 3 show that with increasing amounts of the thiophenol-lignin hybrid material, the degree of crosslinking and various physical properties of the rubber composition first increase and then decrease. This is because the thiophenol-lignin hybrid material contains a large number of hydroxyl groups, which easily aggregate with increasing amounts, affecting the dispersibility of the thiophenol-lignin hybrid material. Therefore, the amount of thiophenol-lignin hybrid material added should not be excessive.

[0053] 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 tread rubber composition for electric vehicle tires containing sulfur-containing phenol-lignin hybrid materials, characterized in that, The rubber composition is prepared by dry mixing, and is made by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: Natural rubber: 45.0-55.0 parts, styrene-butadiene rubber: 22.0-25.0 parts, butadiene rubber: 20.0-30.0 parts, carbon black: 55.0-95.0 parts, thiophenol lignin hybrid material: 8.0-18.0 parts, white oil: 5.0-9.0 parts, antioxidant: 1.0-5.0 parts, activator: 1.0-8.0 parts, coupling agent: 1.5-2.5 parts, paraffin wax: 2.0-4.5 parts, scorching inhibitor: 0.1-0.5 parts, accelerator: 1.0-2.0 parts, vulcanizing agent: 1.0-2.5 parts.

2. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The thiophenol-lignin hybrid material is a hydrophobic thiophenol material containing a large number of sulfur atoms and phenolic hydroxyl groups, obtained by fully reacting lignin with sulfur under alkaline conditions of sodium carboxylate.

3. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The preparation method of the thiophenol-lignin hybrid material includes the following steps: 1) At room temperature, lignin, sulfur, and sodium carboxylate are thoroughly ground and mixed, then placed in a hydrothermal reactor. Deionized water with pH=12 is added, and the solution is stirred until homogeneous. The reaction conditions are adjusted to 80-200℃, and the reaction is continuously stirred for 6.0-48.0 hours. 2) After the reaction is complete, the suspension is stirred and dissolved in an alkaline aqueous solution with pH=8-12 for 0.5-1.5 hours, and then filtered to separate, yielding a dark black liquid; 3) Slowly add hydrochloric acid to the dark black liquid and adjust the pH to 2-6 until no more precipitation occurs; obtain thiophenol lignin hybrid material nanoparticles by centrifugation purification, place the thiophenol lignin hybrid material nanoparticle precipitate obtained after centrifugation in deionized water for dialyzing, and dilute the thiophenol lignin hybrid material nanoparticle suspension to below 1%, and then sonicate it to uniformly disperse it in deionized water. 4) Freeze-drying to obtain thiophenol-lignin hybrid materials.

4. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 3, characterized in that, The weight ratio of lignin to sulfur is 1:0.2-20; And / or, the weight ratio of lignin to sodium carboxylate is 1:0.001-0.2; And / or, the freeze-drying temperature is -45°C to -55°C, and the vacuum degree is 0.10-0.13 mbar.

5. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The dry mixing process includes the following steps: 1) First stage mixing: Rubber, carbon black, activator, antioxidant, white oil and paraffin are mixed, discharged, sheeted and left to stand to obtain the initial masterbatch; 2) Two-stage mixing: The thiophenol lignin hybrid material, coupling agent and initial masterbatch are mixed, discharged, sheeted and left to stand to obtain the compounded rubber; 3) Three-stage mixing: Mix the compound rubber, anti-scorching agent, accelerator and vulcanizing agent, discharge the rubber, sheet it, and let it stand to obtain the final rubber.

6. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The carbon black has a particle size of 20-60 nm.

7. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The antioxidant is antioxidant 4020 and / or antioxidant RD, and / or antioxidant 4010NA, wherein antioxidant 4020 is 0.5-4.0 parts, antioxidant RD is 0.5-2.0 parts, and antioxidant 4010NA is 0.5-1.5 parts.

8. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The activator is zinc oxide and stearic acid, with zinc oxide at 1.0-5.0 parts and stearic acid at 1.0-3.0 parts.

9. The electric vehicle tire tread rubber composition of a sulfur-containing phenol-lignin hybrid material according to claim 1, characterized in that, The coupling agent used is silane coupling agent SI-69.

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