Preparation method of modified tire pyrolysis carbon black and water-based printing color paste

Abstract

The application provides a preparation method of modified tire pyrolysis carbon black and a water-based printing color paste, adopts citric acid to remove ash in the pyrolysis carbon black, adds an oxidizing agent to remove impurities in the carbon black, increase the surface activity of the carbon black, introduce oxygen-containing functional groups on the surface of the carbon black, and then add a modification aid to effectively improve the surface properties of the carbon black and improve the dispersibility of the pyrolysis carbon black in the water-based color paste. The modification method of the tire pyrolysis carbon black is simple in process, high in production efficiency, low in cost and good in economy, the modified pyrolysis carbon black prepared has high purity and strong hydrophilicity, has stronger tinting strength than conventional N326 carbon black, has good matching with polymer resins in the water-based color paste, the color paste has stronger stability, and has good application prospect and popularization value.

Description

Technical Field

[0001] This invention relates to the field of modified carbon black from waste tire pyrolysis, and particularly to a method for preparing modified tire pyrolysis carbon black and an aqueous printing paste. Background Technology

[0002] Globally, 1.7 billion waste tires (approximately 42 million tons) are generated annually, enough to circle the Earth's equator 200 times, and this figure is growing at a rate of 4% per year. China has been the world's largest tire producer for 10 consecutive years, and its annual waste tire production is expected to exceed 330 million tires (over 10 million tons) in 2024. The 440 million vehicles in the country further exacerbate this growth in tire scrapping.

[0003] The current method for tire processing mainly involves pyrolysis technology, which decomposes waste tires at high temperatures to produce fuel oil (40% profit), carbon black, steel wire, and combustible gases. This technology has been implemented on a large scale at the Double Star Ikers plant in Qingdao, China, and has also been promoted through legislation in Germany and the United States.

[0004] Tire pyrolysis carbon black is a solid product generated from waste tires through thermal pyrolysis (400-900℃) under anaerobic, slightly positive pressure conditions. It has an average particle size of 40-50 nm and a structure similar to general-purpose carbon black (GPF), but with a higher ash content (containing silica, cobalt salts, and zinc compounds). Its surface is covered with carbonaceous deposits, affecting its reinforcing properties. Currently, tire pyrolysis carbon black is commonly used in the rubber industry as a reinforcing agent and filler, primarily in tires and shoe soles. Its performance is close to that of petroleum-based carbon black, but at a lower cost.

[0005] However, tire pyrolysis carbon black has problems such as low surface activity, poor dispersibility, and poor compatibility with polymers. At present, the common improvement method is to modify carbon black, mainly including oxidation modification, surface grafting modification, and coating modification. For example, patent document CN115418119A describes a method and application for modifying waste tire pyrolysis carbon black. Specifically, it uses a dodecylbenzene sulfonic acid solution to perform in-situ modification under the action of a ball mill. The resulting modified carbon black product has stable properties and good performance, and can partially replace commercial carbon black in the production of rubber products. Another example is patent document CN118063982A, which discloses a method for modifying waste tire pyrolysis carbon black with trifluoroacetic acid. By mixing carbon black with trifluoroacetic acid and acid washing, the carbon black is modified, resulting in higher effectiveness and better performance, realizing the high-value development of tire pyrolysis carbon black. Yet another example is patent document CN118063983A, which discloses a method for modifying tire pyrolysis carbon black with aminosulfonic acid. Carbon black, aminosulfonic acid, and a dispersant are mixed and acid washed. The aminosulfonic acid reacts with the ash on the surface of the carbon black, thereby improving surface activity and carbon black quality. However, these methods suffer from problems such as complex processes, high costs, and limited modification effects; furthermore, the modified carbon black obtained by these methods has poor hydrophilicity, limiting its application to the rubber industry and thus narrowing its scope. Therefore, developing a simple, efficient, and low-cost method for modifying tire pyrolysis carbon black is of significant practical importance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing modified tire pyrolysis carbon black and an aqueous printing paste. The modification method for tire pyrolysis carbon black provided by this invention is simple, efficient, low-cost, and economical. The modified pyrolysis carbon black prepared has high purity and strong hydrophilicity, and has stronger tinting strength than conventional N326 carbon black. It also has good compatibility with polymer resins in aqueous printing pastes, resulting in stronger stability of the pastes. It has good application prospects and promotional value.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing modified tire pyrolysis carbon black, comprising: mixing tire pyrolysis carbon black with citric acid particles, and then pulverizing the mixture to obtain carbon black particles with uniform particle size. The carbon black particles are mixed with an oxidant and subjected to an oxidation reaction at 70-80°C. After the oxidation reaction, benzoyl peroxide and a coupling agent are added to the solution for modification; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black.

[0008] Preferably, the mass of the citric acid particles is 1-1.2 times the mass of the ash in the tire pyrolysis carbon black.

[0009] Preferably, the mass ratio of the carbon black particles to the oxidant is 1:(2-2.4), and the oxidant is a 1wt%-3wt% aqueous solution of nitric acid.

[0010] Preferably, the oxidation reaction takes 1-2 hours.

[0011] Preferably, the amount of benzoyl peroxide added is 1.5wt%-2.0wt% of the solution mass; And / or, the amount of the coupling agent added is 2wt%-2.5wt% of the solution mass.

[0012] Preferably, the coupling agent is a silane coupling agent.

[0013] Preferably, the modification time is 1-2 hours; And / or, the modification temperature is 80-85℃.

[0014] The present invention also provides an aqueous printing paste comprising modified tire pyrolysis carbon black prepared by the aforementioned preparation method.

[0015] Preferably, the color paste includes modified tire pyrolysis carbon black, dispersant, defoamer, and pH adjuster.

[0016] Preferably, the color paste comprises: 20-30 parts modified tire pyrolysis carbon black, 20-25 parts water-based acrylic resin, 5-10 parts surfactant, 0.005-0.01 parts defoamer, 30-50 parts deionized water, and a pH adjuster. The pH adjuster is used to adjust the pH of the color paste to 7-8.

[0017] This invention provides a method for preparing modified tire pyrolysis carbon black and an aqueous printing paste. The method uses citric acid to remove ash from the pyrolysis carbon black, supplemented by an oxidant to remove impurities and increase the surface activity of the carbon black, while simultaneously introducing oxygen-containing functional groups onto the carbon black surface. Furthermore, by adding modifying agents, the surface properties of the carbon black are effectively improved, enhancing the dispersibility of the pyrolysis carbon black in the aqueous printing paste. The modification method for tire pyrolysis carbon black provided by this invention is simple, efficient, low-cost, and economical. The resulting modified pyrolysis carbon black has high purity and strong hydrophilicity, exhibiting stronger tinting strength than conventional N326 carbon black. It also shows good compatibility with polymer resins in aqueous printing pastes, resulting in stronger stability and promising application prospects and widespread application value. Attached Figure Description

[0018] Figure 1 Comparison of tire pyrolysis carbon black products before and after modification; Figure 2 A comparison chart of the tinting strength of tire pyrolysis carbon black products before and after modification. Detailed Implementation

[0019] This invention provides a method for preparing modified tire pyrolysis carbon black, comprising: mixing tire pyrolysis carbon black with citric acid particles, and then pulverizing the mixture to obtain carbon black particles with uniform particle size. The carbon black particles are mixed with an oxidant and subjected to an oxidation reaction at 70-80°C. After the oxidation reaction, benzoyl peroxide and a coupling agent are added to the solution for modification; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black.

[0020] This invention first mixes tire pyrolysis carbon black with citric acid granules, and then pulverizes the mixture to obtain carbon black granules with uniform particle size. In this invention, the pulverization operation preferably employs dry pulverization, such as using an air jet mill. The pulverized carbon black granules have a uniform particle size, preferably 800-1000 mesh. Uniform particle size ensures high product consistency and improves product quality during subsequent processing. After pulverization, a magnetic separation process is also included to remove iron-containing impurities from the tire pyrolysis carbon black.

[0021] In this invention, the preferred mass of the citric acid particles is 1-1.2 times the mass of the ash in the tire pyrolysis carbon black. Generally, tire pyrolysis carbon black has poor activity and high levels of impurities and ash, therefore pretreatment is usually required. The purpose of adding citric acid in this invention is to remove ash from the pyrolysis carbon black; therefore, the amount of citric acid added depends on the ash content of the pyrolysis carbon black. Since the ash content varies after pyrolysis of different specifications and types of tires, the amount of citric acid added also varies accordingly. To ensure thorough ash removal, the amount of citric acid is generally 1-1.2 times the mass of the ash. This invention does not have special requirements regarding the source of the citric acid particles; commercially available products are sufficient.

[0022] After obtaining carbon black particles with uniform particle size, the present invention mixes the carbon black particles with an oxidant and carries out an oxidation reaction at 70-80°C.

[0023] In this invention, the preferred mass ratio of carbon black particles to the oxidant is 1:(2-2.4), and the preferred oxidant is a 1wt%-3wt% aqueous nitric acid solution. The oxidation reaction time is 1-2 hours. Tire pyrolysis carbon black contains various impurities and an oil film on its surface. This invention uses nitric acid solution as the oxidant, which effectively removes these impurities and the oil film, introducing oxygen-containing functional groups onto the carbon black surface and effectively increasing its surface activity. The hydrochloric acid solution in this invention can be obtained by diluting any high-concentration nitric acid solution with deionized water; the source of the nitric acid solution is not particularly limited, and commercially available products are acceptable.

[0024] After the oxidation reaction, the present invention adds benzoyl peroxide and a coupling agent to the solution for modification.

[0025] In this invention, the amount of benzoyl peroxide added is 1.5wt%-2.0wt% of the solution mass; and / or, the amount of coupling agent added is 2wt%-2.5wt% of the solution mass. In this invention, the coupling agent is a silane coupling agent. In this invention, the modification time is 1-2 hours; and / or, the modification temperature is 80-85℃. In this invention, benzoyl peroxide can be grafted onto the surface of carbon black, changing the surface properties of the carbon black; the silane coupling agent's coating effect on the carbon black can effectively improve the dispersibility of tire pyrolysis carbon black in water-based printing pastes. In this invention, the silane coupling agent is preferably KH-580.

[0026] After modification, the carbon black particles are filtered, washed, and dried to obtain modified tire pyrolysis carbon black. In this invention, filtration, washing, and drying are conventional operations in the art, aimed at removing impurities and reagents remaining from the previous pretreatment and modification processes; parameters can be referenced from conventional parameters in the art, and this application does not impose further limitations.

[0027] This invention also provides an aqueous printing paste comprising modified tire pyrolysis carbon black prepared by the aforementioned method. The modified carbon black obtained by pretreatment for impurity removal and modification in this invention has high purity and strong hydrophilicity, making it suitable for preparing aqueous printing pastes. Compared to the commonly used N326 carbon black on the market, it has stronger tinting strength and better compatibility with polymer resins in aqueous printing pastes, resulting in a more stable paste with promising application prospects and significant promotional value.

[0028] In this invention, the water-based printing paste comprises modified tire pyrolysis carbon black, a dispersant, a defoamer, and a pH adjuster. More preferably, in this invention, the paste comprises: 20-30 parts of modified tire pyrolysis carbon black, 20-25 parts of water-based acrylic resin, 5-10 parts of surfactant, 0.005-0.01 parts of defoamer, 30-50 parts of deionized water, and a pH adjuster; the pH adjuster is used to adjust the pH of the paste to 7-8.

[0029] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] Example 1 A method for preparing modified tire pyrolysis carbon black, comprising: Commercially available tire pyrolysis carbon black (17% ash content) was mixed with citric acid granules (ash to citric acid mass ratio 1:1), and then pulverized by an air jet mill to obtain carbon black granules with a particle size distribution of 800-1000 mesh. 100g of carbon black granules were mixed with 220g of 1wt% nitric acid and subjected to an oxidation reaction at 70℃ for 2 hours. Add 5g of benzoyl peroxide and 4g of silane coupling agent KH580 to the solution and modify it at 80℃ for 1 hour; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black①.

[0031] Example 2 A method for preparing modified tire pyrolysis carbon black, comprising: Commercially available tire pyrolysis carbon black (17% ash content) was mixed with citric acid granules (ash to citric acid mass ratio 1:1), and then pulverized by an air jet mill to obtain carbon black granules with a particle size distribution of 800-1000 mesh. 100g of carbon black granules were mixed with 220g of 2wt% nitric acid and subjected to an oxidation reaction at 75°C for 1.5 hours. Add 5g of benzoyl peroxide and 4g of silane coupling agent KH580 to the solution and modify it at 80℃ for 1.5 hours; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black ②.

[0032] Example 3 A method for preparing modified tire pyrolysis carbon black, comprising: Commercially available tire pyrolysis carbon black (25% ash content) was mixed with citric acid granules (ash to citric acid mass ratio 1:1.2), and then pulverized by an air jet mill to obtain carbon black granules with a particle size distribution of 800-1000 mesh. 100g of carbon black granules were mixed with 220g of 2wt% nitric acid and subjected to an oxidation reaction at 80℃ for 2 hours. Add 5g of benzoyl peroxide and 4g of silane coupling agent KH580 to the solution and modify it at 85℃ for 1 hour; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black ③.

[0033] Example 4 A method for preparing modified tire pyrolysis carbon black, comprising: Commercially available tire pyrolysis carbon black (25% ash content) was mixed with citric acid granules (ash to citric acid mass ratio 1:1.2), and then pulverized by an air jet mill to obtain carbon black granules with a particle size distribution of 800-1000 mesh. 100g of carbon black granules were mixed with 220g of 3wt% nitric acid and subjected to an oxidation reaction at 75℃ for 2 hours. Add 5g of benzoyl peroxide and 4g of silane coupling agent KH580 to the solution and modify it at 80℃ for 2 hours; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black④.

[0034] Comparative Example 1 A method for preparing modified tire pyrolysis carbon black, comprising: Commercially available tire pyrolysis carbon black (17% ash content) was mixed with citric acid granules (ash to citric acid mass ratio 1:1), and then pulverized by an air jet mill to obtain carbon black granules with a particle size distribution of 800-1000 mesh. 100g of carbon black granules were mixed with 220g of 1wt% nitric acid and subjected to an oxidation reaction at 75°C for 2 hours. Modified tire pyrolysis carbon black can be obtained by filtering, washing and drying carbon black particles.

[0035] Comparative Example 2 In the above embodiments, the commercially available tire pyrolysis carbon black (17% ash content) is referred to as carbon black ⑥.

[0036] Comparative Example 3 In the above embodiments, the commercially available tire pyrolysis carbon black (25% ash content) is referred to as carbon black ⑦.

[0037] All the carbon blacks obtained in the above examples and comparative examples were prepared according to the water-based printing paste formulation: 25 parts carbon black, 20 parts water-based acrylic resin, 5 parts surfactant, 40 parts deionized water, 0.01 parts defoamer, and pH adjusted to 7 with pH adjuster (MP95). The resulting pastes were labeled as paste ①, paste ②, paste ③, paste ④, paste ⑤, paste ⑥, and paste ⑦.

[0038] Performance metrics testing: 1. Tinting strength test: conducted according to ASTM D3265 standard. As can be seen from the table above, the ash content in tire pyrolysis carbon black can be effectively partially removed after the initial pretreatment, thereby reducing the impurities in the tire pyrolysis carbon black; and the nitrile oxidation and modification process can significantly improve the coloring power of tire pyrolysis carbon black.

[0039] 2. Ash content test: conducted according to ASTM D1506 standard. As can be seen from the table above, the ash content in tire pyrolysis carbon black can be effectively partially removed after the initial pretreatment, and the addition of citric acid can further reduce the ash content in the carbon black.

[0040] 3. Storage stability test: The pigment was stored at 60℃ for 1 week, and the changes in its state were observed and the particle size was tested. 4. Compatibility test with water-based resin: Mix water-based colorant and water-based PU resin, and observe whether there is any coarsening or particle formation. The performance comparison above shows that this application effectively improves the surface activity, dispersibility, and compatibility with polymers of tire pyrolysis carbon black by combining physical and chemical modifications, thereby improving the tinting strength of tire pyrolysis carbon black, reducing raw material costs, and increasing the added value of tire pyrolysis carbon black.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing modified tire pyrolysis carbon black, characterized in that, Tire pyrolysis carbon black was mixed with citric acid particles and then pulverized to obtain carbon black particles with uniform particle size. The carbon black particles are mixed with an oxidant and subjected to an oxidation reaction at 70-80°C. After the oxidation reaction, benzoyl peroxide and a coupling agent are added to the solution for modification; After modification, the carbon black particles are filtered, washed and dried to obtain modified tire pyrolysis carbon black.

2. The preparation method according to claim 1, characterized in that, The mass of the citric acid particles is 1-1.2 times the mass of the ash in the tire pyrolysis carbon black.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the carbon black particles to the oxidant is 1:(2-2.4), and the oxidant is a 1wt%-3wt% aqueous solution of nitric acid.

4. The preparation method according to claim 1, characterized in that, The oxidation reaction takes 1-2 hours.

5. The preparation method according to claim 1, characterized in that, The amount of benzoyl peroxide added is 1.5wt%-2.0wt% of the solution mass; And / or, the amount of the coupling agent added is 2wt%-2.5wt% of the solution mass.

6. The preparation method according to claim 1 or 5, characterized in that, The coupling agent is a silane coupling agent.

7. The preparation method according to claim 1, characterized in that, The modification process takes 1-2 hours; And / or, the modification temperature is 80-85℃.

8. A water-based printing paste, characterized in that, It includes the modified tire pyrolysis carbon black prepared by the preparation method described in claims 1-7.

9. The color paste according to claim 8, characterized in that, The color paste includes modified tire pyrolysis carbon black, dispersant, defoamer, and pH adjuster.

10. The color paste according to claim 8 or 9, characterized in that, The color paste comprises: 20-30 parts modified tire pyrolysis carbon black, 20-25 parts water-based acrylic resin, 5-10 parts surfactant, 0.005-0.01 parts defoamer, 30-50 parts deionized water, and pH adjuster. The pH adjuster is used to adjust the pH of the color paste to 7-8.

Images