Modified waste tire pyrolysis carbon black for rubber reinforcement and preparation method thereof

Abstract

This invention discloses a modified waste tire pyrolysis carbon black for rubber reinforcement and its preparation method, relating to the technical field of reinforcing fillers for polymer compositions. The method involves pretreatment, solvent deblocking, chelation deashing, and inert atmosphere heat treatment of the waste tire pyrolysis carbon black, followed by the construction of a glycol underlayer and a borate ester network layer on its surface to obtain the modified pyrolysis carbon black and its application evaluation method in the SBR system. The beneficial effects of this invention are: the modified filler exhibits reduced flow resistance during processing in the rubber compound, more controllable vulcanization process, and a more stable vulcanization plateau, indicating suppressed agglomeration, improved dispersion uniformity, and a more substantial contribution to effective crosslinking; simultaneous improvement in reinforcement and wear resistance at the vulcanized rubber level, indicating enhanced interfacial bonding, more continuous stress transmission, and reduced defect sources; dynamic mechanical results show reduced loss in the high-temperature zone and a smoother curve, indicating reduced interfacial friction and energy dissipation.

Description

Technical Field

[0001] This invention relates to the field of reinforcing fillers for polymer compositions, and particularly to a modified waste tire pyrolysis carbon black for rubber reinforcement and its preparation method. Background Technology

[0002] Thermopyrolysis of waste tires can simultaneously recover oil, gas, steel wire, and pyrolyzed carbon black (CBp). Among these, pyrolyzed carbon black, due to its certain carbon skeleton and reinforcing potential, is considered one of the resource recovery directions to replace some commercial carbon black. In recent years, the industry has gradually shifted from "using pyrolyzed carbon black as a low-end filler" to "achieving rubber reinforcement applications through purification and structural control." Common approaches include removing metal / inorganic ash, reducing residual oil and coke deposits, and restoring or controlling pore structure and surface active sites. This is combined with processing, vulcanization, and mechanical and abrasion resistance evaluations in SBR, NR / BR, and other systems to verify its substitutability.

[0003] Current methods for upgrading pyrolysis carbon black generally face a "triple coupling problem": First, residual oil / coke deposits during pyrolysis can cover pores and surface active sites, leading to poor mixing and dispersion, increased processing viscosity, and unstable vulcanization behavior. Second, ash and inorganic salts (such as inorganic components from Zn and Si) can easily form hard particles or weak interfacial regions, causing discontinuous stress transmission, deterioration of wear resistance, and potential interference with the vulcanization system. Third, even if oil and ash content are reduced through purification, the pore structure and surface state of pyrolysis carbon black may still be mismatched with the rubber matrix, resulting in fluctuations in the reinforcing effect under different working conditions, making it difficult to replicate stably. To address the aforementioned issues, most publicly available solutions employ strong acid / alkali washing, rewashing, or solvent extraction to reduce ash and volatile matter. For instance, while the "acid washing + alkali washing + re-acid washing" purification process disclosed in patent CN102504619B can significantly reduce ash and improve reinforcement, the multi-step acid and alkali treatment introduces equipment corrosion and waste liquid treatment burdens. Furthermore, the disturbance to the pore structure and surface condition is difficult to control precisely, resulting in uncertainty regarding the "performance stability after purification." Similarly, CN111574859A proposes a treatment system that uses superheated steam stripping to remove oil and combines it with metal recovery, which can reduce oil content and improve subsequent aqueous phase treatment. However, such processes often focus on the single objective of "oil removal / recovery," and the synergistic control between "ash content, pore structure, and interface compatibility" is insufficient, potentially leading to uneven improvements in processing and reinforcement performance and significant batch-to-batch fluctuations. Therefore, the main shortcoming of existing technologies is not "whether purification is possible", but rather the difficulty in simultaneously achieving, under industrially reproducible conditions: effective removal of deposits, reduction of ash interference, maintenance or restoration of pore structure / surface condition, and the resulting stable improvement in key properties such as processing, vulcanization, and wear resistance.

[0004] Therefore, there is an urgent need for a pyrolysis carbon black upgrading route for rubber reinforcement applications that can synergistically solve key problems such as "dispersion difficulties caused by oil / coke coverage", "interface weakening and abrasion aggravation caused by ash / salts", and "reinstability of reinforcement caused by pore structure and surface state" without introducing uncontrollable side reactions and unstable operating conditions. This would enable the resulting filler to achieve repeatable and verifiable comprehensive improvements in the controllability of mixing and vulcanization processes, as well as the reinforcement and wear resistance of vulcanized rubber, thereby supporting the stable application of pyrolysis carbon black in rubber systems. Summary of the Invention

[0005] The purpose of this invention is to provide a modified waste tire pyrolysis carbon black product for rubber reinforcement applications and its preparation method, so as to synergistically improve the compatibility of its pore structure and surface state with the rubber matrix under industrially reproducible conditions, thereby achieving more stable and repeatable performance in terms of mixing and processing, vulcanization process controllability, and vulcanized rubber reinforcement and wear resistance.

[0006] To achieve the above-mentioned objectives and address the aforementioned technical problems, this invention provides a method for preparing modified waste tire pyrolysis carbon black for rubber reinforcement, comprising the following steps: S1 processes waste tire pyrolysis carbon black by screening, magnetic separation to remove iron, and drying. S2 involves contacting the pyrolysis carbon black obtained in step S1 with an organic solvent and then performing solid-liquid separation to obtain unblocked pyrolysis carbon black. S3 The unblocking pyrolysis carbon black obtained in step S2 is placed in a chelating deashing solution for deashing reaction, and then the solid and liquid are separated. After washing with water and drying, deashed pyrolysis carbon black is obtained. S4 The deashed pyrolysis carbon black obtained in step S3 is heat-treated under inert gas protection and cooled to obtain pyrolysis carbon black with restored pore structure. S5 involves sequentially constructing a diol underlayer and a borate ester network layer on the pore structure-restored pyrolysis carbon black obtained in step S4 to obtain modified waste tire pyrolysis carbon black, wherein: S5-1 The diol substrate is constructed by: contacting the polyol with the pore structure-restored pyrolysis carbon black, followed by solid-liquid separation and drying, to obtain the diol substrate pyrolysis carbon black. The borate ester network layer described in S5-2 is constructed by placing the diol-based pyrolysis carbon black obtained in step S5-1 in an aqueous system of polyvinyl alcohol and boron source, and then performing solid-liquid separation and drying after polyvinyl alcohol and boron source form a borate ester network layer on the surface of the diol-based pyrolysis carbon black.

[0007] Preferably, in step S1, the waste tire pyrolysis carbon black is screened and magnetically separated to remove iron, and then dried at 80-110°C to constant weight.

[0008] Preferably, the organic solvent in step S2 is selected from ester solvents or carbonate solvents.

[0009] Preferably, in step S2, the solid-liquid ratio of the organic solvent to the pyrolyzed carbon black is 1:3 to 1:8, the contact treatment temperature is 50 to 70°C, the contact treatment time is 10 to 60 min, and step S2 is performed at least twice.

[0010] Preferably, the chelating deashing solution in step S3 contains 0.2 to 0.6 wt% chelating agent and 0.3 to 0.8 wt% citric acid, with the remainder being deionized water, and the pH is adjusted to 5.2 to 5.8 with sodium bicarbonate.

[0011] Preferably, the unblocking pyrolysis carbon black obtained in step S2 is mixed with the chelated deashing liquid at a solid-liquid ratio of 1:8 to 1:15, stirred at 50 to 70°C for 60 to 120 min, and then the solid and liquid are separated. The mixture is washed with deionized water until the conductivity of the filtrate is not higher than 200 μS / cm, and then dried at 70 to 100°C to obtain deashed pyrolysis carbon black.

[0012] Preferably, in step S4, the deashed pyrolysis carbon black is heated to 420–520°C under inert gas protection and held for 20–60 min, and then cooled to obtain pyrolysis carbon black with restored pore structure.

[0013] Preferably, the inert gas is carbon dioxide.

[0014] Preferably, in step S5-1, the pore structure restored pyrolysis carbon black obtained in step S4 is added to a mixed solution of ethanol and water in a volume ratio of (90-98):(2-10), and 0.5-2.0 wt% of polyol is added based on the mass of the pyrolysis carbon black. After stirring at 40-60°C for 30-90 min, solid-liquid separation is performed and the mixture is dried at 60-100°C to obtain diol-based pyrolysis carbon black.

[0015] Preferably, in step S5-2, the diol bottom layer pyrolysis carbon black obtained in step S5-1 is added to the aqueous phase system of polyvinyl alcohol and dispersed, then a boron source is added and the pH of the system is adjusted to 8.3-8.6, so that polyvinyl alcohol and boron source form a borate ester network layer on the surface of the diol bottom layer pyrolysis carbon black. After solid-liquid separation, washing with deionized water 1-2 times and drying, modified waste tire pyrolysis carbon black is obtained.

[0016] Preferably, the polyvinyl alcohol is a polyvinyl alcohol with a degree of hydrolysis of 88% ± 1%, and the amount of polyvinyl alcohol used in the aqueous system is 1.0 to 3.0 wt% based on the mass of the glycol-based pyrolysis carbon black; the boron source is a combination of borax and boric acid, wherein the amount of borax is 0.3 to 1.0 wt% based on the mass of the glycol-based pyrolysis carbon black, and the amount of boric acid is 0.1 to 0.5 wt% based on the mass of the glycol-based pyrolysis carbon black; and the pH of the system is controlled at 7.8 to 8.2 before adding the boron source, and then the pH of the system is adjusted to 8.3 to 8.6 after adding the boron source.

[0017] Preferably, the aqueous phase system in step S5-2 further includes an anionic dispersant, which is one of sodium lignosulfonate and sodium polyacrylate, and its dosage is 0.01 to 0.20 wt% based on the mass of the glycol-based pyrolysis carbon black.

[0018] This application also provides a modified waste tire pyrolysis carbon black for rubber reinforcement, which is prepared by the above-described preparation method.

[0019] The beneficial effects of the technical solution provided by this invention are as follows: When the pyrolysis carbon black treated according to this invention is used in SBR formulations, the resulting compound exhibits lower processing viscosity and lower shear torque, with a more controllable vulcanization process and a more stable vulcanization plateau. These results indicate that filler agglomeration in the compound is suppressed, resulting in more uniform dispersion, reduced internal friction and flow resistance, and more effective crosslinking contribution, thereby minimizing performance dispersion caused by processing fluctuations and uneven vulcanization.

[0020] The system of this invention can achieve a higher level of reinforcement and significantly reduce wear loss, manifested in more continuous stress transmission, stronger interfacial bonding, and fewer defect sources. This effect is consistent with the technical path of this invention, which reduces agglomeration and interfacial debonding through "deposit removal—ash removal—pore structure restoration—interfacial layer construction," and macroscopically verifies that the problem of unstable reinforcement by pyrolysis carbon black has been improved.

[0021] The system of this invention exhibits a lower tanδ and a more stable curve in the high-temperature region, indicating reduced interfacial friction and energy dissipation, and decreased dynamic performance fluctuations. This effect is consistent with enhanced interfacial coupling and more uniform filler-rubber interaction, which can be used to demonstrate that the performance improvement of this invention is not solely achieved by increasing the degree of crosslinking, but rather by reducing dynamic losses through interfacial structure optimization.

[0022] The system of this invention exhibits smaller agglomerates and fewer interfacial defects, resulting in a smoother extrusion strip surface and reduced particle protrusions and fisheye defects. These visualization results are consistent with the trends of reduced processing viscosity, stable vulcanization platform, improved reinforcement and wear resistance, and decreased high-temperature tanδ. Both the microstructure and processing characteristics confirm that this invention substantially improves the key issues of "difficult dispersion and weak interfacial bonding." Attached Figure Description

[0023] Figure 1 The diagram shows the dynamic mechanical properties of the vulcanizates in Example 1 and Comparative Examples 4, 5, and 6 of this invention. Figure 2 The images shown are SEM images of the cross-sections of the vulcanized rubber in Example 1 and Comparative Examples 4 and 5 of this invention. Figure 3The images show the extruded appearance of the rubber compound in Example 1 and Comparative Examples 1, 4, and 5 of this invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example 1 This embodiment provides a method for preparing modified waste tire pyrolysis carbon black for rubber reinforcement, which is carried out according to the following steps: S1 Preprocessing After screening and magnetic separation to remove iron from waste tire pyrolysis carbon black, it is dried at 95°C to constant weight to obtain pretreated pyrolysis carbon black.

[0026] S2 Unblocking Processing The pretreated pyrolysis carbon black obtained in step S1 was mixed with the organic solvent ethyl acetate at a solid-liquid ratio of 1:5. After stirring and contacting at 62°C for 35 min, solid-liquid separation was performed and the solid was collected. Then, ethyl acetate was mixed again at a solid-liquid ratio of 1:5, and after stirring and contacting at 62°C for 25 min, solid-liquid separation was performed. The obtained solid was dried at 75°C to obtain unblocked pyrolysis carbon black.

[0027] S3 deashing treatment Preparation of chelating deashing solution: The chelating deashing solution contains 0.50 wt% chelating agent disodium ethylenediaminetetraacetate (EDTA-Na2), 0.60 wt% citric acid, and the remainder is deionized water, with the pH adjusted to 5.6 by sodium bicarbonate.

[0028] The unblocking pyrolysis carbon black obtained in step S2 is mixed with the chelated deashing liquid at a solid-liquid ratio of 1:12. After stirring and reacting at 62°C for 100 min, the solid and liquid are separated. The solid is washed with deionized water until the conductivity of the filtrate is not higher than 200 μS / cm. The washed solid is dried at 85°C to obtain deashed pyrolysis carbon black.

[0029] S4 Hole Structure Restoration Treatment The deashed pyrolysis carbon black obtained in step S3 was heated to 495°C and held for 45 min under inert gas protection, and then cooled to obtain pyrolysis carbon black with restored pore structure.

[0030] S5 Surface Co-construction Processing S5-1 Construction of the diol substrate: The pore structure restored pyrolysis carbon black obtained in step S4 was added to a mixed solution of ethanol and water in a volume ratio of 96:4. 1.6 wt% of polyol glycerol based on the mass of the pyrolysis carbon black was added. After stirring at 52°C for 70 min, solid-liquid separation was performed, and the mixture was dried at 80°C to obtain the diol substrate pyrolysis carbon black.

[0031] S5-2 Construction of the borate ester network layer: Preparation of a polyvinyl alcohol aqueous phase system: Using deionized water as the medium, polyvinyl alcohol with a degree of hydrolysis of 88% ± 1% was added, making the amount of polyvinyl alcohol 2.2 wt% based on the mass of the glycol-based pyrolysis carbon black; sodium lignosulfonate, an anionic dispersant, was added to the aqueous phase system, with an amount of 0.12 wt% based on the mass of the glycol-based pyrolysis carbon black. The glycol-based pyrolysis carbon black obtained in step S5-1 was added to the polyvinyl alcohol aqueous phase system and dispersed, controlling the pH of the system to 8.0; then a boron source combination was added in one step, wherein the amount of borax was 0.8 wt% based on the mass of the glycol-based pyrolysis carbon black, and the amount of boric acid was 0.30 wt% based on the mass of the glycol-based pyrolysis carbon black; after adding the boron source, the pH of the system was adjusted to 8.5, so that polyvinyl alcohol and boron source formed a borate ester network layer on the surface of the glycol-based pyrolysis carbon black; after the reaction was completed, the solid and liquid were separated, washed twice with deionized water, and then dried at 85℃ to obtain modified waste tire pyrolysis carbon black.

[0032] Example 2 Prepared using the same method as in Example 1, except that: In step S2, the solid-liquid ratio of ethyl acetate to pretreated pyrolysis carbon black is 1:3, the contact treatment temperature is 50℃, the contact treatment time is 10 min each time, and two contact treatments are performed.

[0033] Example 3 Prepared using the same method as in Example 1, except that: In step S2, the solid-liquid ratio of ethyl acetate to pretreated pyrolysis carbon black is 1:8, the contact treatment temperature is 70℃, the contact treatment time is 60 min each time, and two contact treatments are performed.

[0034] Example 4 Prepared using the same method as in Example 1, except that: In step S3, the chelating deashing solution contains 0.20 wt% EDTA-Na2 and 0.30 wt% citric acid, with the pH adjusted to 5.2; and the solid-liquid ratio of the unblocked cracked carbon black to the chelating deashing solution is 1:8, the deashing temperature is 50℃, and the deashing time is 60 min.

[0035] Example 5 Prepared using the same method as in Example 1, except that: In step S3, the chelating deashing solution contains 0.60 wt% EDTA-Na2 and 0.80 wt% citric acid, with the pH adjusted to 5.8; and the solid-liquid ratio of the unblocked cracked carbon black to the chelating deashing solution is 1:15, the deashing temperature is 70℃, and the deashing time is 120 min.

[0036] Example 6 Prepared using the same method as in Example 1, except that: In step S4, the heating temperature is 420℃ and the holding time is 20 min.

[0037] Example 7 Prepared using the same method as in Example 1, except that: In step S4, the heating temperature is 520℃ and the holding time is 60 min.

[0038] Example 8 Prepared using the same method as in Example 1, except that: In step S5-1, the volume ratio of ethanol to water is 90:10, the amount of glycerol used is 0.5 wt%, the stirring temperature is 40℃, the stirring time is 30 min, and the drying temperature is 60℃.

[0039] Example 9 Prepared using the same method as in Example 1, except that: In step S5-1, the volume ratio of ethanol to water is 98:2, the amount of glycerol is 2.0 wt%, the stirring temperature is 60℃, the stirring time is 90 min, and the drying temperature is 100℃.

[0040] Example 10 Prepared using the same method as in Example 1, except that: In step S5-2, the amount of polyvinyl alcohol used is 1.0 wt%, and the amount of sodium lignosulfonate used is 0.01 wt%; the pH of the system before adding the boron source is 7.8, and the pH of the system after adding the boron source is 8.3; the amount of borax used is 0.3 wt%, and the amount of boric acid used is 0.10 wt%; the washing is performed once.

[0041] Example 11 Prepared using the same method as in Example 1, except that: In step S5-2, the amount of polyvinyl alcohol used is 3.0 wt%, and the amount of sodium lignosulfonate used is 0.20 wt%; the pH of the system before adding the boron source is 8.2, and the pH of the system after adding the boron source is 8.6; the amount of borax used is 1.0 wt%, and the amount of boric acid used is 0.50 wt%; the number of washing times is 2.

[0042] Example 12 Prepared using the same method as in Example 1, except that: In step S2, the organic solvent is replaced by dimethyl carbonate instead of ethyl acetate (the remaining conditions in S2 are the same as in Example 1).

[0043] Comparative Example 1 Prepared using the same method as in Example 1, except that: Step S2 is omitted, meaning that after step S1, the organic solvent contact treatment to unblock the blockage is not performed, and the process proceeds directly to step S3 for chelation and deashing treatment.

[0044] Comparative Example 2 Prepared using the same method as in Example 1, except that: Step S3 is omitted, meaning that after step S2, the chelation and deashing process is not performed, and the process proceeds directly to step S4 for heat treatment under inert gas protection.

[0045] Comparative Example 3 Prepared using the same method as in Example 1, except that: Step S4 is omitted, meaning that after step S3, heat treatment under inert gas protection is not performed, and the process proceeds directly to step S5 to construct the diol bottom layer and the borate ester network layer.

[0046] Comparative Example 4 Prepared using the same method as in Example 1, except that: Step S5-1 is omitted, that is, after step S4, the polyol contact treatment is not performed to form the diol bottom layer. Instead, the pyrolysis carbon black with restored pore structure obtained in step S4 is directly placed in the aqueous system of polyvinyl alcohol and boron source in step S5-2 to construct the borate ester network layer.

[0047] Comparative Example 5 Prepared using the same method as in Example 1, except that: In step S5-2, borax and boric acid are not added; only polyvinyl alcohol with a degree of hydrolysis of 88% ± 1% is added (the amount is the same as in Example 1), and the other conditions are kept the same as in Example 1.

[0048] Comparative Example 6 The preparation method is the same as in Example 1, except that after adding the boron source in step S5-2, the pH of the system is not adjusted to 8.3-8.6, but the pH of the system is controlled at 7.0 before solid-liquid separation, washing and drying.

[0049] Application examples (1) Formula (based on 100 parts of SBR, unit: parts) SBR 100; Test carbon black 50; Zinc oxide 5; Stearic acid 2; Antioxidant 4020 1.5; Antioxidant RD 1.0; Paraffin wax 1.0; Naphthenic oil 5; Sulfur 1.5; Accelerator CBS 1.2; Accelerator TMTD 0.2.

[0050] (2) Mixing A two-stage mixing process is adopted: First stage masterbatch mixing: After adding SBR to the internal mixer and plasticizing for 30-60 seconds, add 1 / 2 of the test carbon black and mix for about 1 minute; then add zinc oxide, stearic acid, antioxidant 4020, antioxidant RD, paraffin / microcrystalline wax and process oil and continue mixing for 2-3 minutes; then add the remaining 1 / 2 of the test carbon black and continue mixing for 2-3 minutes, controlling the discharge temperature at 145-155℃, and then sheet and cool. The second stage of final mixing: After cooling the masterbatch, sulfur, accelerator CBS and accelerator TMTD are added on a two-roll mill or under low-temperature internal mixing conditions. The mixture is mixed evenly, and the final mixing temperature is controlled not to exceed 105℃. The mixture is then sheeted out for use.

[0051] (3) Sulfidation The final rubber compound was vulcanized, and the vulcanization conditions were determined according to the tc90 of the vulcanization curve to obtain SBR vulcanized rubber samples.

[0052] Experimental test: 1) Mooney viscosity Standard adopted: GB / T 1232.1-2016.

[0053] 2) Vulcanization curve According to standard GB / T 9869.3-2025 "Determination of vulcanization properties of rubber using vulcanizing apparatus - Part 3: Rotorless vulcanizing apparatus" 3) Tensile properties According to standard GB / T 528-2009, "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". 4) Wear resistance Recommended standard: GB / T 9867-2008 "Determination of abrasion resistance of vulcanized rubber or thermoplastic rubber (rotary roller abrasion test method)" 5) DMA tanδ near 0℃; tanδ in the 60–80℃ range Table 1 Processing and vulcanization characteristics of rubber compound

[0054] Based on the Mooney viscosity and vulcanization curves, the rubber compound using the modified pyrolysis carbon black of this invention exhibits lower processing viscosity, lower minimum torque, and a higher and more stable vulcanization plateau. Simultaneously, the positive vulcanization time is more controllable, indicating that the filler is more uniformly dispersed in the rubber compound, the system has lower flow resistance, and the effective crosslinking contribution is more substantial. In contrast, the control sample lacking a deblocking step suffers from agglomeration and orifice shielding due to residual pyrolysis oil / tar deposits, resulting in increased processing viscosity and a decreased vulcanization plateau. Control samples lacking a diol substrate, boron source, or with pH deviations make it difficult for the interfacial layer to continuously build on the filler surface, leading to a regression in dispersion and crosslinking effects. This manifests as higher processing viscosity, a lower vulcanization plateau, or increased fluctuations in the vulcanization process, thus verifying that "interfacial synergistic construction" is key to stable processing and vulcanization behavior.

[0055] Table 2 Mechanical and abrasion resistance properties of vulcanized rubber

[0056] From the perspectives of mechanics and wear resistance, the modified pyrolysis carbon black system of this invention exhibits a more complete reinforcement effect and lower wear loss, indicating more continuous stress transmission, stronger interfacial bonding, and fewer agglomeration defects. Control samples lacking declogging or deashing steps suffer from weakened interfaces and defect concentration due to oil film coverage and inorganic ash residue, resulting in decreased reinforcement levels and significantly increased wear. Control samples lacking a diol underlayer or boron source have difficulty forming a stable borate ester network interfacial layer, leading to insufficient improvement in reinforcement and wear resistance. This further demonstrates that "diol anchoring + borate ester network layer" directly contributes to improving reinforcement stability and suppressing wear. Furthermore, compared to commercial carbon black controls, the modified pyrolysis carbon black of this invention exhibits similar or better overall performance in terms of reinforcement and wear resistance, proving that this synergistic modification route can effectively compensate for the inherent defects of pyrolysis carbon black and achieve the expected technical effects.

[0057] The interfacial synergistic modification of this invention significantly improves the dispersion and interfacial bonding of fillers in the adhesive, thereby reducing dynamic loss and improving the stability of the processed appearance. Specifically, Figure 1 The results show that Example 1 has a lower overall tanδ and a more stable curve in the high-temperature region, while Comparative Examples 4 / 5 / 6 have a higher tanδ and more obvious separation in this region. This indicates that when there is a lack of diol substrate, a lack of boron source, or a pH deviation, the boron ester network layer is difficult to form stably, leading to increased interfacial friction and energy dissipation. Figure 2 In Example 1, there were fewer aggregates in the cross section, smaller in size and more uniformly distributed, and relatively fewer interface voids / pull-out marks. In contrast, Comparative Examples 4 and 5 showed more obvious agglomeration and interface defects, indicating that the diol anchoring and borate ester network layer directly contribute to inhibiting agglomeration and enhancing interface adhesion. Figure 3In Example 1, the extruded strip surface was smoother with fewer particle protrusions and "fish eyes," while in Comparative Examples 4 / 5 / 1, the appearance was rougher and the defects were more obvious, further visually confirming the difference in dispersion and interface stability from the processing end.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing modified waste tire pyrolysis carbon black for rubber reinforcement, characterized in that, Includes the following steps: S1 processes waste tire pyrolysis carbon black by screening, magnetic separation to remove iron, and drying. S2 involves contacting the pyrolysis carbon black obtained in step S1 with an organic solvent and then performing solid-liquid separation to obtain unblocked pyrolysis carbon black. S3 The unblocking pyrolysis carbon black obtained in step S2 is placed in a chelating deashing solution for deashing reaction, and then the solid and liquid are separated. After washing with water and drying, deashed pyrolysis carbon black is obtained. S4 The deashed pyrolysis carbon black obtained in step S3 is heat-treated under inert gas protection and cooled to obtain pyrolysis carbon black with restored pore structure. S5 involves sequentially constructing a diol underlayer and a borate ester network layer on the pore structure-restored pyrolysis carbon black obtained in step S4 to obtain modified waste tire pyrolysis carbon black, wherein: S5-1 The diol substrate is constructed by: contacting the polyol with the pore structure-restored pyrolysis carbon black, followed by solid-liquid separation and drying, to obtain the diol substrate pyrolysis carbon black. The borate ester network layer described in S5-2 is constructed by placing the diol-based pyrolysis carbon black obtained in step S5-1 in an aqueous solution of polyvinyl alcohol and a boron source, allowing the polyvinyl alcohol and the boron source to form a borate ester network layer on the surface of the diol-based pyrolysis carbon black, followed by solid-liquid separation and drying.

2. The preparation method according to claim 1, characterized in that, The organic solvent mentioned in step S2 is selected from ester solvents or carbonate solvents.

3. The preparation method according to claim 1, characterized in that, In step S2, the solid-liquid ratio of the organic solvent to the pyrolyzed carbon black is 1:3 to 1:8, the contact treatment temperature is 50 to 70°C, and the contact treatment time is 10 to 60 min.

4. The preparation method according to claim 1, characterized in that, The chelating deashing solution in step S3 contains 0.2-0.6 wt% chelating agent and 0.3-0.8 wt% citric acid, with the remainder being deionized water, and the pH is adjusted to 5.2-5.

8.

5. The preparation method according to claim 4, characterized in that, The unblocking pyrolysis carbon black obtained in step S2 is mixed with the chelated deashing liquid at a solid-liquid ratio of 1:8 to 1:15, then the solid and liquid are separated, washed with deionized water, and then dried to obtain deashed pyrolysis carbon black.

6. The preparation method according to claim 1, characterized in that, In step S4, the deashed pyrolysis carbon black is heated to 420–520°C under inert gas protection and held for 20–60 min.

7. The preparation method according to claim 1, characterized in that, In step S5-1, the pore structure restored pyrolysis carbon black obtained in step S4 is added to a mixed solution of ethanol and water, and 0.5 to 2.0 wt% of polyol is added based on the mass of the pyrolysis carbon black. Then, solid-liquid separation and drying are performed to obtain diol bottom layer pyrolysis carbon black.

8. The preparation method according to claim 1, characterized in that, In step S5-2, the diol-based pyrolysis carbon black obtained in step S5-1 is added to the aqueous phase system of polyvinyl alcohol and dispersed. Then, a boron source is added and the pH of the system is adjusted to 8.3-8.6, so that polyvinyl alcohol and boron source form a borate ester network layer on the surface of the diol-based pyrolysis carbon black. After solid-liquid separation, washing and drying, modified waste tire pyrolysis carbon black is obtained.

9. The preparation method according to claim 8, characterized in that, The polyvinyl alcohol is a polyvinyl alcohol with a degree of hydrolysis of 88% ± 1%, and the amount of polyvinyl alcohol used in the aqueous system is 1.0 to 3.0 wt% based on the mass of the glycol-based pyrolysis carbon black. The boron source is a combination of borax and boric acid, wherein the amount of borax is 0.3 to 1.0 wt% based on the mass of the glycol-based pyrolysis carbon black, and the amount of boric acid is 0.1 to 0.5 wt% based on the mass of the glycol-based pyrolysis carbon black. The pH of the system is controlled at 7.8 to 8.2 before adding the boron source, and the pH of the system is adjusted to 8.3 to 8.6 after adding the boron source.

10. A modified waste tire pyrolysis carbon black for rubber reinforcement, characterized in that, The modified waste tire pyrolysis carbon black for rubber reinforcement is prepared by any one of the preparation methods of claims 1-9.

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