Deep functional modification method of waste tire thermal cracking carbon black, obtained carbon black and application

Abstract

The invention discloses a deep functional modification method of waste tire thermal cracking carbon black. The method comprises the following steps: treating thermal cracking carbon black at a high temperature of 300-500 DEG C; adding the thermal cracking carbon black subjected to high-temperature treatment into an alkaline solution, continuously mechanically stirring until the solution is uniform, filtering, washing with water, and drying to obtain thermal cracking carbon black subjected to alkaline liquor treatment; and mixing the obtained thermal cracking carbon black treated by the alkali liquor with a surfactant, carrying out heat treatment to obtain a modified thermal cracking carbon black suspension, transferring the obtained carbon black suspension into a reaction kettle, sealing the reaction kettle, heating, and reacting under a sealed condition to obtain the deeply functionalized modified thermal cracking carbon black. The modified cracked carbon black can be used for preparing a rubber compound. According to the modification method disclosed by the invention, the ash content of the thermal cracking carbon black is reduced, the surface activity of the thermal cracking carbon black is enhanced, the reinforcing performance of the thermal cracking carbon black in rubber is improved, and the use amount of the thermal cracking carbon black is increased, so that the thermal cracking carbon black has wider application.

Description

Technical Field

[0001] This invention belongs to the technical field of modification of waste tire pyrolysis carbon black, specifically involving a method for deep functionalization modification of waste tire pyrolysis carbon black, the resulting carbon black, and its applications. Background Technology

[0002] With the rapid development of my country's social economy, the automotive industry has experienced explosive growth, leading to a surge in tire consumption. Waste tires, often referred to as "black pollution," have caused severe environmental damage. Traditional methods such as direct landfilling, tire retreading, and rubber powder production suffer from environmental pollution, limited applicability, and resource waste. Therefore, recycling waste tires into rubber powder is a widely accepted approach. However, undesulfurized rubber powder is porous and has poor adhesion. The pyrolysis treatment of waste tires, considered an environmentally friendly and efficient method, effectively disposes of waste tires while maximizing their utilization, yielding valuable byproducts, which is of great significance.

[0003] The pyrolysis of waste tires involves converting waste polymers or biomass into smaller molecules and solid products at suitable temperatures in an oxygen-free or inert atmosphere. Pyrolysis carbon black, a key byproduct of the tire pyrolysis process, possesses many unique advantages and is an important reinforcing filler in rubber applications. Compared to industrial carbon black, pyrolysis carbon black offers greater economic benefits, costing approximately 1 / 2 to 1 / 3 of its price. Due to its excellent abrasion resistance and strength, pyrolysis carbon black is widely used in tires and other rubber products. It significantly improves the durability and service life of rubber products, reduces wear and tear, thereby enhancing the overall performance and safety of the products.

[0004] However, pyrolytic carbon black is a type of carbon black produced through a thermal cracking process. For a long time, it has suffered from poor reinforcing properties, falling short of industrial carbon black and thus hindering the development of the entire thermal cracking industry. Currently, researchers have conducted in-depth studies on the composition, microstructure, and reinforcing properties of pyrolytic carbon black produced from macroscopic and microscopic perspectives. However, no effective method has been found to improve the performance of pyrolytic carbon black, and its performance in reinforcing rubber has not yet surpassed or reached that of industrial carbon black in terms of rubber reinforcement. (References: Ma Lan, Zhang Zhen, Zhang Yuxin, et al. Research progress on pyrolytic carbon black technology for waste rubber. Synthetic Rubber [J]. 2021, 44(3): 232-239. Sun Yanzhi, Sun Chaohua, Lin Ziyang, et al. Modification and application progress of pyrolytic carbon black from waste tires. Fine Chemicals [J]. 2022, 39(10): 1999-2004. Chen Mingxing, Zhou Zhifeng, Chen Ruijun, et al. A method for modifying pyrolytic carbon black from waste tires. CN118165551A.)

[0005] Pyrolytic carbon black generally requires modification to restore its reinforcing properties and enable its application in rubber products, thereby increasing its added value and application range. Typically, methods such as reducing particle size, using modifiers, and acid washing to remove ash can improve the reinforcing properties of pyrolytic carbon black. However, ultrafine carbon black particles significantly increase production costs for companies. Modifiers alone offer limited improvement in rubber performance, and acid washing increases environmental costs. Furthermore, strong acids significantly increase the surface activity of pyrolytic carbon black, making carbon black particles more prone to agglomeration and reducing its dispersibility in rubber. All of these methods are insufficient to achieve high-performance carbon black or meet national standards.

[0006] Therefore, there is an urgent need for a method that can deeply functionalize and modify pyrolytic carbon black, effectively reduce the ash content of pyrolytic carbon black, and effectively modify the surface of pyrolytic carbon black to avoid its agglomeration in the rubber matrix. Summary of the Invention

[0007] The purpose of this invention is to provide a method for deep functionalization modification of waste tire pyrolysis carbon black, so as to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Step 1: Treat the pyrolysis carbon black at a high temperature of 300-500℃.

[0009] Step 2: Add the high-temperature treated pyrolysis carbon black from Step 1 to the alkaline solution and continuously stir mechanically until the solution is homogeneous. Then filter, wash with water, and dry to obtain the alkaline-treated pyrolysis carbon black.

[0010] Step 3: The alkaline-treated pyrolysis carbon black obtained in Step 2 is mixed with a surfactant and heat-treated to obtain a modified pyrolysis carbon black suspension. The surfactant is one or more of coupling agents, nonionic surfactants, or anionic surfactants.

[0011] Step 4: Transfer the carbon black suspension obtained in Step 3 into the reaction vessel, seal the reaction vessel, heat it, and carry out the reaction under sealed conditions to obtain deeply functionalized modified pyrolysis carbon black.

[0012] Preferably, the particle size of the pyrolysis carbon black in step one is 15-30 μm, the high-temperature treatment is carried out under nitrogen atmosphere or vacuum conditions, the high-temperature treatment temperature is 400-450℃, the heating rate is 10-20℃ / min, and the treatment time is 30 min-1 h.

[0013] More preferably, the heating rate in step one is 15°C / min.

[0014] Preferably, the alkaline solution in step two is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate; the concentration of the alkaline solution is 1-5 wt%; the mechanical stirring speed is 2000-3500 rpm, and the stirring time is 0.5-2 h; the number of water washings is 2-3; the drying temperature is 90-110℃, and the drying time is 2-6 h; the amount of carbon black added is 5-50 wt% of the alkaline solution.

[0015] More preferably, in step two, the mechanical stirring speed is 3000 rpm, and the amount of carbon black added is 20-30 wt% of the alkaline solution.

[0016] Preferably, the coupling agent in step three is a titanate coupling agent or a silane coupling agent, the nonionic surfactant is polyethylene glycol, and the anionic surfactant is stearic acid or carboxymethyl cellulose; the amount of surfactant is 2-5 wt% of the amount of carbon black.

[0017] More preferably, the amount of surfactant used in step three is 3-4 wt% of the amount of carbon black.

[0018] Preferably, the reactor in step four is a hydrothermal reactor with a working pressure of 1-3 MPa, a temperature of 120-180℃, and heating is carried out in a drying oven at a heating rate of 5-10℃ / min for a reaction time of 2-6 h.

[0019] More preferably, the working pressure of the reactor in step four is 2 MPa, the temperature is 150-160℃, and the reaction time is 4h.

[0020] The above-mentioned method for deep functionalization modification of waste tire pyrolysis carbon black can yield deeply functionalized pyrolysis carbon black.

[0021] The applications of the deep functionalized modified pyrolysis carbon black obtained above include: its use in the preparation of compound rubber.

[0022] The beneficial effects of this invention are as follows: Compared with the traditional method of directly acid washing for modifying pyrolysis carbon black, this invention uses a method of high-temperature pretreatment followed by alkaline washing, which can more efficiently reduce ash content and improve alkaline washing efficiency. Subsequently, hydrothermal high-pressure modification with surfactants yields deeply functionalized pyrolysis carbon black, effectively improving its surface activity, reinforcing properties in rubber, and mechanical properties of pyrolysis carbon black / rubber composites, thus broadening its application prospects. Furthermore, the preparation process is simple and low-cost, which is of great significance for the recycling and application of solid carbon black. Attached Figure Description

[0023] Figure 1This is an electron microscope image of pyrolyzed carbon black.

[0024] Figure 2 The image shows an electron microscope image of the modified pyrolysis carbon black prepared in Example 3.

[0025] Figure 3 This is the EDS diagram of pyrolysis carbon black.

[0026] Figure 4 The image shows the EDS diagram of the modified pyrolysis carbon black prepared in Example 3. Detailed Implementation

[0027] To make the technical objectives, solutions, and effects of this invention easier to understand, the invention will be described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only for further illustration and should not be construed as limiting the scope of protection of this invention. Non-essential improvements and adjustments made by those skilled in the art based on the content of this invention are still within the scope of protection of this invention. All raw materials used in the embodiments are conventionally available commercial raw materials.

[0028] Example 1 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 300°C under a nitrogen atmosphere or vacuum at a rate of 10°C / min, held at this temperature for 1 h, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was added to a 1 wt% ammonia solution (5 wt% of the carbon black in the alkaline solution), mechanically stirred at 2000 rpm for 0.5 h, filtered and washed twice with water, and dried at 110°C for 2 h. The alkaline-treated pyrolytic carbon black was then mixed with a titanate coupling agent at a mass ratio of 2 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 1 MPa, a temperature of 180°C, a heating rate of 5°C / min, and a reaction time of 6 h to obtain deeply functionalized modified pyrolytic carbon black.

[0029] The chemical properties of the modified pyrolysis carbon black obtained in Example 1 are shown in Table 1.

[0030] Example 2 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 500°C under a nitrogen atmosphere or vacuum at a rate of 20°C / min, held at that temperature for 30 min, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was then added to a 5 wt% ammonia solution (50 wt% of the alkaline solution), mechanically stirred at 3500 rpm for 2 h, filtered, washed twice with water, and dried at 110°C for 2 h. The alkaline-treated pyrolytic carbon black was then mixed with stearic acid at a mass ratio of 5 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 3 MPa, a temperature of 120°C, a heating rate of 5°C / min, and a reaction time of 6 h to obtain deeply functionalized modified pyrolytic carbon black.

[0031] The chemical properties of the modified pyrolysis carbon black obtained in Example 2 are shown in Table 1.

[0032] Example 3 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 400°C under a nitrogen atmosphere or vacuum at a rate of 15°C / min, held at this temperature for 30 min, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was then added to a 5 wt% sodium hydroxide solution, with the carbon black amount being 20 wt% of the alkali solution. Mechanical stirring was performed at 3000 rpm for 2 h. The mixture was then filtered, washed twice with water, and dried at 110°C for 2 h. The alkali-treated pyrolytic carbon black was then mixed with a silane coupling agent at a mass ratio of 4 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 2 MPa, a temperature of 150°C, a heating rate of 10°C / min, and a reaction time of 4 h to obtain deeply functionalized modified pyrolytic carbon black.

[0033] The chemical properties of the modified pyrolysis carbon black obtained in Example 3 are shown in Table 1.

[0034] Example 4 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 450°C under a nitrogen atmosphere or vacuum at a rate of 10°C / min, held at this temperature for 30 min, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was then added to a 5 wt% sodium bicarbonate solution (30 wt% of the alkali solution), mechanically stirred at 3000 rpm for 2 h, filtered, washed twice with water, and dried at 110°C for 2 h. The alkali-treated pyrolytic carbon black was then mixed with a silane coupling agent at a mass ratio of 3 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 2 MPa, a temperature of 160°C, a heating rate of 10°C / min, and a reaction time of 4 h to obtain deeply functionalized modified pyrolytic carbon black.

[0035] The chemical properties of the modified pyrolysis carbon black obtained in Example 4 are shown in Table 1.

[0036] Comparative Example 1 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 200°C under a nitrogen atmosphere or vacuum at a rate of 10°C / min, held at this temperature for 1 h, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was then added to a 1 wt% ammonia solution (5 wt% of the carbon black in the alkaline solution), mechanically stirred at 2000 rpm for 0.5 h, filtered and washed twice with water, and dried at 110°C for 2 h. The alkaline-treated pyrolytic carbon black was then mixed with a titanate coupling agent at a mass ratio of 2 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 1 MPa, a temperature of 180°C, a heating rate of 5°C / min, and a reaction time of 6 h to obtain the modified pyrolytic carbon black.

[0037] The chemical properties of the modified pyrolysis carbon black obtained in Comparative Example 1 are shown in Table 1.

[0038] Comparative Example 2 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 500°C under a nitrogen atmosphere or vacuum at a rate of 20°C / min, held at that temperature for 30 min, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was then added to a 5 wt% ammonia solution (50 wt% of the alkaline solution), mechanically stirred at 3500 rpm for 2 h, filtered, washed twice with water, and dried at 110°C for 2 h. The alkaline-treated pyrolytic carbon black was then mixed with stearic acid at a mass ratio of 1 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 3 MPa, a temperature of 120°C, a heating rate of 5°C / min, and a reaction time of 6 h to obtain the modified pyrolytic carbon black.

[0039] The chemical properties of the modified pyrolysis carbon black obtained in Comparative Example 2 are shown in Table 1.

[0040] Comparative Example 3 A method for deep functionalization modification of waste tire pyrolysis carbon black includes the following steps: Pyrolytic carbon black was placed in a muffle furnace and heated from room temperature to 500°C under a nitrogen atmosphere or vacuum at a rate of 20°C / min, held at that temperature for 30 min, and then cooled to room temperature. The high-temperature treated pyrolytic carbon black was then added to a 10 wt% sodium hydroxide solution, with the carbon black amount being 5 wt% of the alkali solution. Mechanical stirring was performed at 2000 rpm for 2 h. The mixture was then filtered, washed twice with water, and dried at 110°C for 2 h. The alkali-treated pyrolytic carbon black was then mixed with a silane coupling agent at a mass ratio of 5 wt% of the carbon black to obtain a modified pyrolytic carbon black suspension. The suspension was transferred to a hydrothermal reactor at a working pressure of 1 MPa, a temperature of 120°C, a heating rate of 10°C / min, and a reaction time of 4 h to obtain the modified pyrolytic carbon black.

[0041] The chemical properties of the modified pyrolysis carbon black obtained in Comparative Example 3 are shown in Table 1.

[0042] Performance testing of modified pyrolysis carbon black The modified pyrolysis carbon black prepared in Examples 1-4 and Comparative Examples 1-3 of this invention were subjected to chemical performance tests, and the test results are shown in Table 1.

[0043] The lower the ash content, the fewer inorganic impurities in the carbon black, and the higher its purity. High ash content directly affects product performance; for example, in rubber, it reduces vulcanization efficiency and causes cracking; in conductive materials, it hinders electron conduction and reduces conductivity. High light transmittance means fewer organic impurities on the carbon black surface, resulting in better compatibility with matrix materials such as rubber and resin. This avoids "blooming," excessive odor, or performance degradation caused by impurity migration. Oil absorption value reflects the "structure" of carbon black particles, that is, the ability of the "chain-like and network-like voids" formed by the aggregation of carbon black particles to hold oil. The higher the structure, the higher the oil absorption value. Carbon black with a high oil absorption value has a loose structure and is suitable for high reinforcement in rubber. The higher the iodine absorption value, the larger the specific surface area. Carbon black with a large specific surface area and high surface activity can enhance the reinforcing effect and increase tensile strength in rubber, and easily form a conductive network in conductive materials. In the field of catalysis, a high specific surface area can provide more active sites and improve catalytic efficiency.

[0044] Ash content and toluene extract transmittance determine the basic purity of carbon black, while oil absorption value, iodine absorption value, and specific surface area determine the activity and compatibility of carbon black. As shown in Table 1, factors such as the heat treatment temperature of pyrolysis carbon black, the concentration of surfactant, and the concentration of alkaline solution have a significant impact on the ash content, toluene extract transmittance, iodine absorption value, oil absorption value, and specific surface area of ​​the modified carbon black. Considering all data, the modified pyrolysis carbon black prepared in the examples exhibits better overall performance.

[0045] Depend on Figure 1 and Figure 2 It can be seen that, compared to untreated pyrolysis carbon black, the surface morphology of high-temperature treated pyrolysis carbon black has a smaller and more uniform particle size, with blurred particle edges and varying shapes. This may be due to the further removal of residual organic components from the pyrolysis process. Furthermore, during the high-temperature and high-pressure hydrothermal reactor treatment, pyrolysis carbon black also undergoes deep functionalization modification. Figure 3 and Figure 4 It can be seen that the oxygen content of the pyrolysis carbon black treated in the hydrothermal reactor is increased, which is beneficial to improving the bonding ability between carbon black and rubber.

[0046] Table 1 Chemical property test of modified pyrolysis carbon black Deeply functionalized modified pyrolysis carbon black is used in the preparation of compound rubber. The modified pyrolysis carbon black prepared in Examples 1-4 and Comparative Examples 1-3, as well as pyrolysis carbon black and industrial carbon black N660, were used in rubber compound formulations, and their performance comparison data are shown in Table 2. The rubber compound formulations were prepared according to GB / T3780.18—2017 "Identification Method of Carbon Black in Natural Rubber (NR)," with the following specific mass fractions: 100 parts natural rubber, 3.0 parts stearic acid, 5.0 parts zinc oxide, 0.6 parts accelerator DM, 2.5 parts sulfur, and 50 parts carbon black or pyrolysis carbon black. As can be seen from Table 2, the modified pyrolysis carbon black of this invention exhibits superior performance compared to standard pyrolysis carbon black. The performance of the modified pyrolysis carbon black basically reaches the level of national standard carbon black N660, and some properties, such as elongation and tear strength, are even higher than those of standard carbon black N660.

[0047] Table 2. Performance comparison of modified pyrolysis carbon black in rubber compounds with pyrolysis carbon black and N660 in rubber compounds.

Claims

1. A method for deep functionalization modification of waste tire pyrolysis carbon black, characterized in that, It comprises the following steps: Step one: treating the pyrolysis carbon black at high temperature of 300-500℃; Step two: adding the pyrolysis carbon black treated at high temperature in step one into an alkaline solution, continuously stirring mechanically until the solution is uniform, then filtering, washing with water and drying to obtain the pyrolysis carbon black treated with alkaline solution; Step three: mixing the pyrolysis carbon black treated with alkaline solution obtained in step two with a surfactant to obtain a suspension of modified pyrolysis carbon black after heat treatment, wherein the surfactant is one or several of coupling agent, non-ionic surfactant or anionic surfactant; Step four: moving the suspension of carbon black obtained in step three into a reaction kettle, sealing the reaction kettle, heating and reacting under closed conditions to obtain the deeply functionalized modified pyrolysis carbon black.

2. The method according to claim 1, wherein the method is characterized by, In step one, the particle size of the pyrolysis carbon black is 15-30 μm, the high temperature treatment is carried out under nitrogen atmosphere or vacuum condition, the high temperature treatment temperature is 400-450℃, the heating rate is 10-20℃ / min, and the treatment time is 30 min-1 h.

3. The method according to claim 2, wherein the method is characterized by, In step one, the heating rate is 15℃ / min.

4. The method of claim 1, wherein the method further comprises the step of adding a functional group to the carbon black. 5 In step two, the alkaline solution is one or several of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate and sodium bicarbonate; the concentration of the alkaline solution is 1-5 wt%; the mechanical stirring speed is 2000-3500 rpm, the stirring time is 0.5-2 h; the water washing times are 2-3 times; the drying temperature is 90-110℃, the drying time is 2-6 h; and the addition amount of carbon black is 5-50 wt% of the alkaline solution.

5. The method of claim 4, wherein the method further comprises the step of: In step two, the mechanical stirring speed is 3000 rpm, and the addition amount of carbon black is 20-30 wt% of the alkaline solution.

6. The method of claim 1, wherein the method further comprises the step of: In step three, the coupling agent is titanium ester coupling agent or silane coupling agent, the non-ionic surfactant is polyethylene glycol, and the anionic surfactant is stearic acid or carboxymethyl cellulose; the amount of the surfactant is 2-5 wt% of the amount of carbon black.

7. The method of claim 6, wherein the method further comprises the step of adding a functional group to the carbon black. In step three, the amount of the surfactant is 3-4 wt% of the amount of carbon black.

8. The method of claim 1, wherein the method is characterized by, In step four, the reaction kettle is a hydrothermal reaction kettle, the working pressure is 1-3 MPa, the temperature is 120-180℃, the heating is carried out in a drying oven, the heating rate is 5-10℃ / min, and the reaction time is 2-6 h.

9. The method of claim 8, wherein the method further comprises the step of adding a functional group to the carbon black. In step four, the working pressure of the reaction kettle is 2 MPa, the temperature is 150-160℃, and the reaction time is 4 h.

10. The deeply functionalized modified pyrolysis carbon black obtained by the method according to any one of claims 1-9 and the application thereof.

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