Process for wet mixing of composite rubber by pyrolytic carbon black

Abstract

The invention discloses a process for wet-process mixing of composite rubber by pyrolytic carbon black, and relates to the technical field of wet-process rubber mixing, and the process comprises the following steps: (1) dispersing pyrolytic carbon black in water to form a liquid-phase dispersion; (2) uniformly dispersing natural latex in water, uniformly mixing the natural latex with the liquid-phase dispersoid, then performing flocculation, washing, dehydrating and drying a flocculating constituent to obtain wet-process master batch; and (3) mixing and vulcanizing the wet-process rubber master batch and an auxiliary agent according to ingredients to obtain the composite rubber. In the process, the pyrolytic carbon black is subjected to three-step surface treatment, so that the stability in the rubber is high, and the mechanical property and the wear resistance of the composite rubber are greatly improved.

Description

Technical Field

[0001] The invention relates to a wet rubber mixing process, in particular to a process for wet mixing of pyrolytic carbon black composite rubber. Background Art

[0002] Waste tires are mainly composed of 60-65% rubber, 20-35% carbon black and some additives. During the processing of tires, the elastomers, sulfur and host in the rubber undergo cross-linking reactions to form insoluble cross-linked elastomers, which have high strength and elasticity and are not easy to decompose. Therefore, waste tires are not only large in size, but also not easy to degrade naturally. They are one of the largest sources of solid waste. Recycling and reusing waste tires is of great significance to the realization of circular economy and intensive utilization of resources.

[0003] Currently, the most commonly used recycling method for waste tires is pyrolysis of waste tires. The heating process can break the chemical bonds in the rubber material and eventually decompose it into pyrolysis gas, pyrolysis oil and pyrolysis carbon black, thereby achieving resource recycling. Pyrolysis carbon black can be reused in rubber products as a reinforcing material.

[0004] At present, the main problems of using pyrolytic carbon black for rubber reinforcement are: 1. During the pyrolysis process, hydrocarbon molecules in the rubber are adsorbed on the surface of the pyrolytic carbon black and adhere to some charred substances, resulting in relatively large aggregates. In addition, due to the uneven distribution of rubber, carbon black, etc. in waste tires, the particle size distribution of the pyrolytic carbon black is uneven; 2. After the pyrolysis of pyrolytic carbon black, the surface functional groups are reduced and the activity is low, which affects its dispersibility and stability in rubber. 3. The commonly used surface modification methods are acid washing or coupling agent surface modification. The problems of this modification method are: the surface of the pyrolytic carbon black is etched after acid washing, and the reinforcement performance deteriorates. In addition, the use of coupling agent modification can improve the parting performance of pyrolytic carbon black, but the functional group volume of the coupling agent is relatively large, which affects the combination of pyrolytic carbon black and rubber, resulting in poor wear resistance of rubber. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a process for wet mixing of pyrolytic carbon black composite rubber to address the deficiencies of the prior art. In the process, the pyrolytic carbon black undergoes three steps of surface treatment, has strong stability in rubber, and greatly increases the mechanical properties and wear resistance of the composite rubber.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A process for wet mixing of pyrolytic carbon black composite rubber comprises the following steps: (1) dispersing pyrolytic carbon black in water to form a liquid dispersion; (2) Dispersing natural rubber latex uniformly in water, mixing it uniformly with the liquid phase dispersion, and then flocculating it. The flocculent is washed, dehydrated, and dried to obtain a wet masterbatch. (3) Mixing the wet masterbatch and the additives according to the ingredients and vulcanizing them to obtain the composite rubber; In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically comprises the following steps: After grinding the pyrolytic carbon black, disperse it in an acid solution with a pH of 2.0-3.0 and stir it at 40 °C for 2 h; The water glass solution is added drop by drop into the mixed solution formed in the above steps under stirring, and the mixture is stirred for reaction for 8-10 hours. The product is filtered, washed and dried to obtain SiO2-CBp, and the weight ratio of the water glass to the pyrolytic carbon black is 0.5-1:10.

[0007] Furthermore, in step (2), the weight ratio of natural rubber latex dry rubber to pyrolytic carbon black is 1:0.6-0.7.

[0008] Further, the surface pretreatment also includes the following steps: Ultrasonic dispersion of SiO2-CBp in 1-2wt% ‌Tween-60 aqueous solution, heating to 70°C, adding paraffin, ultrasonic dispersion for 20 min, cooling to room temperature, filtering, washing and drying; The dried product was transferred to an ethanol-water solution, PE6800 was added, stirred and reacted for 10 h, washed with petroleum ether, filtered, washed with water and ethanol, and dried to obtain the product; The weight ratio of the SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin is 10:0.5-0.8:50:30-40.

[0009] Furthermore, the ingredients of step (3) are, by weight: 60 parts of wet masterbatch, 15-21 parts of epoxidized natural rubber, 3-5 parts of modified starch, 3-5 parts of microcrystalline cellulose, 1.0-1.5 parts of zinc oxide, 0.7-0.8 parts of antioxidant RD, 0.5-0.7 parts of sulfur, and 0.8-1.0 parts of accelerator 2-mercaptobenzothiazole.

[0010] Furthermore, the modified starch is prepared by the following steps: Dissolve carboxymethyl starch in an appropriate amount of 15% ethanol aqueous solution, add sodium hydroxide and stir for 30 minutes, then add benzoyl chloride, heat to 35°C, react for 30-40 minutes, adjust to neutral with acid, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0011] Furthermore, in the step (3), the wet masterbatch is first added to an internal mixer, and epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant are added for mixing, with an initial temperature of 90°C and mixing for 6 minutes; entering an open mixer, the roller spacing of the open mixer is set to 2 mm, the rollers are passed three times, and then the minimum roller spacing is adjusted for thin pass, and accelerators and sulfur are added when the rubber is rolled, and after rolling three times, the roller spacing is adjusted to 3 mm for sheeting; vulcanization: the vulcanization conditions are 150°C and 10MPa.

[0012] The beneficial effects of the present invention are: 1. The present invention discloses a process for wet mixing of pyrolytic carbon black composite rubber, wherein the surface of the pyrolytic carbon black of waste tires is treated in three steps, and then a wet mixing process is adopted. Modified starch and microcrystalline cellulose are added to the ingredients as reinforcing fillers, wherein the modified starch is a modified amphiphilic starch. Therefore, the reinforcing fillers such as the pyrolytic carbon black, modified starch and microcrystalline cellulose can be evenly dispersed in the rubber, and a strong interaction force is formed between the rubber and the rubber, thereby greatly increasing the mechanical properties and wear resistance of the composite rubber.

[0013] 2. The pyrolytic carbon black in this application adopts a three-step surface treatment process; since the surface of the pyrolytic carbon black contains a large amount of carbon or ash, this application first uses acid etching to reduce the ash and increase the surface area, and then drips a water glass solution. Under acidic conditions, the water glass solution forms a composite (SiO2-CBp) in which silicon dioxide is deposited on the surface of the pyrolytic carbon black, which can improve the surface strength of the pyrolytic carbon black and increase its reinforcement performance. Since SiO2-CBp loaded with silicon dioxide on the surface is hydrophilic, it can be evenly dispersed in water and is more suitable for wet mixing.

[0014] However, since there are many functional groups such as hydroxyl groups on its surface and its surface free energy is relatively high, its dispersion performance in rubber during the mixing process is relatively poor, which can easily affect the mechanical strength of the vulcanized rubber. Therefore, the present application further performs surface treatment on the SiO2-CBp after loading with silica. First, paraffin is used to protect part of its surface, and then PE6800 is used for modification. After removing the paraffin, an amphiphilic structure is formed, which can be evenly dispersed in the wet process. In the subsequent mixing process, it can also be evenly distributed in the rubber through hydrogen bonds, hydrophobic effects, and electrostatic effects, which greatly increases the mechanical properties of the mixed rubber of the present application. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with specific embodiments.

[0016] Example 1 A process for wet mixing of pyrolytic carbon black composite rubber comprises the following steps: (1) Mixing pyrolytic carbon black and water into a 25% liquid dispersion; (2) Dispersing natural rubber latex (solid content 60%) uniformly in water, mixing with the liquid dispersion uniformly, and then dropping 5wt% calcium chloride for flocculation. The flocculent is washed, dehydrated, and dried to obtain a wet masterbatch. The weight ratio of natural rubber latex dry rubber to pyrolytic carbon black is 1:0.6. (3) First, add the wet masterbatch into the internal mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing, the initial temperature is 90℃, the rotor speed is 80r, and the mixing is 6min; enter the open mixer, the roller distance of the open mixer is set to 2mm, the roller is passed three times, and then the minimum roller distance is adjusted for thin pass. When the rubber is wrapped around the roller, the accelerator and sulfur are added, and the rubber is cut to make the rubber evenly dispersed. After rolling three times, the roller distance is adjusted to 3mm for sheeting; vulcanization: the vulcanization conditions are 150℃, 10MPa, time t 90 *1.3 (1.3 times of the positive vulcanization time) to obtain composite rubber.

[0017] The above-mentioned mixed ingredients are calculated by weight: 60 parts of wet masterbatch, 15 parts of epoxidized natural rubber, 3 parts of modified starch, 3 parts of microcrystalline cellulose, 1.0 part of zinc oxide, 0.7 parts of antioxidant RD, 0.5 parts of sulfur, and 0.8 parts of accelerator 2-mercaptobenzothiazole.

[0018] In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically includes the following steps: After grinding the pyrolytic carbon black, mix it with hydrochloric acid solution at a weight ratio of 1:20, the pH of the hydrochloric acid solution is 2.5, and stir the reaction at 40°C for 2 h; 4 wt% water glass solution was added dropwise into the mixed solution formed in the above steps under stirring, and the mixture was stirred for reaction for 8 hours, and SiO2-CBp was obtained by filtering, washing and drying. The weight ratio of water glass to pyrolytic carbon black was 0.5:10. The SiO2-CBp was ultrasonically dispersed in a 1.5wt% ‌Tween-60 aqueous solution, heated to 70°C, paraffin was added, ultrasonically dispersed for 20 min, cooled to room temperature, filtered, washed and dried; The dried product was transferred to a 4-fold weight ethanol-water solution (the volume ratio of ethanol to water was 1:1), PE6800 was added and stirred for 10 hours, and the paraffin was removed by washing with petroleum ether, then filtered, washed with water and ethanol, and dried to obtain the product; wherein the weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin was 10:0.5:50:30.

[0019] Modified starch is prepared by the following steps: Dissolve carboxymethyl starch in 3 times the weight of 15% vol ethanol aqueous solution, add sodium hydroxide and stir for 30 minutes, then add benzoyl chloride, heat to 35°C, react for 30-40 minutes, neutralize with glacial acetic acid to neutrality, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0020] Example 2 A process for wet mixing of pyrolytic carbon black composite rubber comprises the following steps: (1) Mixing pyrolytic carbon black and water into a 25% liquid dispersion; (2) Dispersing natural rubber latex (solid content 60%) uniformly in water, mixing with the liquid dispersion uniformly, and then dropping 5 wt % calcium chloride for flocculation. The flocculent is washed, dehydrated, and dried to obtain a wet masterbatch. The weight ratio of natural rubber latex dry rubber to pyrolytic carbon black is 1:0.65. (3) First, add the wet masterbatch into the internal mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing, the initial temperature is 90℃, the rotor speed is 80r, and the mixing is 6min; enter the open mixer, the roller distance of the open mixer is set to 2mm, the roller is passed three times, and then the minimum roller distance is adjusted for thin pass. When the rubber is wrapped around the roller, the accelerator and sulfur are added, and the rubber is cut to make the rubber evenly dispersed. After rolling three times, the roller distance is adjusted to 3mm for sheeting; vulcanization: the vulcanization conditions are 150℃, 10MPa, time t 90 *1.3, get composite glue.

[0021] The ingredients are calculated by weight: 60 parts of wet masterbatch, 18 parts of epoxidized natural rubber, 4 parts of modified starch, 4 parts of microcrystalline cellulose, 1.2 parts of zinc oxide, 0.75 parts of antioxidant RD, 0.6 parts of sulfur, and 0.9 parts of accelerator 2-mercaptobenzothiazole.

[0022] In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically includes the following steps: After grinding the pyrolytic carbon black, mix it with nitric acid solution at a weight ratio of 1:20, the pH of the nitric acid solution is 2.5, and react at 40°C with stirring for 2 h; 4 wt% water glass solution was added dropwise into the mixed solution formed in the above steps under stirring, and the mixture was stirred for reaction for 8 hours, filtered, washed and dried to obtain SiO2-CBp, wherein the weight ratio of water glass to pyrolytic carbon black was 0.6:10; The SiO2-CBp was ultrasonically dispersed in a 1.5wt% ‌Tween-60 aqueous solution, heated to 70°C, paraffin was added, ultrasonically dispersed for 20 min, cooled to room temperature, filtered, washed and dried; The dried product was transferred to a 4-fold weight ethanol-water solution (the volume ratio of ethanol to water was 1:1), PE6800 was added and stirred for 10 hours, and after washing with petroleum ether, it was filtered, washed with water and ethanol, and dried to obtain the product; the weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin was 10:0.6:50:30.

[0023] Modified starch is prepared by the following steps: Dissolve carboxymethyl starch in 3 times the weight of 15% vol ethanol aqueous solution, add sodium hydroxide and stir for 30 minutes, then add benzoyl chloride, heat to 35°C, react for 30-40 minutes, neutralize with glacial acetic acid to neutrality, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0024] Example 3 A process for wet mixing of pyrolytic carbon black composite rubber comprises the following steps: (1) Mixing pyrolytic carbon black and water into a 25% liquid dispersion; (2) dispersing natural rubber latex (solid content 60%) uniformly in water, mixing uniformly with the liquid dispersion, and then dropping 5 wt % calcium chloride for flocculation. The flocculent is washed, dehydrated, and dried to obtain a wet masterbatch, wherein the weight ratio of the natural rubber latex dry rubber to the pyrolytic carbon black is 1:0.7; (3) First, add the wet masterbatch into the internal mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing, the initial temperature is 90℃, the rotor speed is 80r, and the mixing is 6min; enter the open mixer, the roller distance of the open mixer is set to 2mm, the roller is passed three times, and then the minimum roller distance is adjusted for thin pass. When the rubber is wrapped around the roller, the accelerator and sulfur are added, and the rubber is cut to make the rubber evenly dispersed. After rolling three times, the roller distance is adjusted to 3mm for sheeting; vulcanization: the vulcanization conditions are 150℃, 10MPa, time t 90 *1.3, get composite glue.

[0025] The ingredients are calculated by weight: 60 parts of wet masterbatch, 20 parts of epoxidized natural rubber, 4.5 parts of modified starch, 4.5 parts of microcrystalline cellulose, 1.4 parts of zinc oxide, 0.75 parts of antioxidant RD, 0.7 parts of sulfur, and 0.9 parts of accelerator 2-mercaptobenzothiazole.

[0026] In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically includes the following steps: After grinding the pyrolytic carbon black, mix it with acid solution at a weight ratio of 1:20, the pH of the acid solution is 2.5, and react at 40°C with stirring for 2h; Under stirring, 4 wt% water glass solution was added dropwise into the mixed solution formed in the above step, stirred for reaction for 9 hours, filtered, washed and dried to obtain SiO2-CBp, wherein the weight ratio of water glass to pyrolytic carbon black was 0.8:10; The SiO2-CBp was ultrasonically dispersed in a 1.5wt% ‌Tween-60 aqueous solution, heated to 70°C, paraffin was added, ultrasonically dispersed for 20 min, cooled to room temperature, filtered, washed and dried; The dried product was transferred to a 5-fold weight ethanol-water solution (the volume ratio of ethanol to water was 1:1), PE6800 was added and stirred for 10 hours, and after washing with petroleum ether, it was filtered, washed with water and ethanol, and dried to obtain the product; the weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin was 10:0.7:50:40.

[0027] Modified starch is prepared by the following steps: Dissolve carboxymethyl starch in 3 times the weight of 15% vol ethanol aqueous solution, add sodium hydroxide and stir for 30 minutes, then add benzoyl chloride, heat to 35°C, react for 30-40 minutes, neutralize with glacial acetic acid to neutrality, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0028] Example 4 A process for wet mixing of pyrolytic carbon black composite rubber comprises the following steps: (1) Mixing pyrolytic carbon black and water into a 25% liquid dispersion; (2) dispersing natural rubber latex (solid content 60%) uniformly in water, mixing uniformly with the liquid dispersion, and then dropping 5 wt % calcium chloride for flocculation. The flocculent is washed, dehydrated, and dried to obtain a wet masterbatch, wherein the weight ratio of the natural rubber latex dry rubber to the pyrolytic carbon black is 1:0.7; (3) First, add the wet masterbatch into the internal mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing, the initial temperature is 90℃, the rotor speed is 80r, and the mixing is 6min; enter the open mixer, the roller distance of the open mixer is set to 2mm, the roller is passed three times, and then the minimum roller distance is adjusted for thin pass. When the rubber is wrapped around the roller, the accelerator and sulfur are added, and the rubber is cut to make the rubber evenly dispersed. After rolling three times, the roller distance is adjusted to 3mm for sheeting; vulcanization: the vulcanization conditions are 150℃, 10MPa, time t 90 *1.3, get composite glue.

[0029] The ingredients are calculated by weight: 60 parts of wet masterbatch, 21 parts of epoxidized natural rubber, 5 parts of modified starch, 5 parts of microcrystalline cellulose, 1.5 parts of zinc oxide, 0.8 parts of antioxidant RD, 0.7 parts of sulfur, and 1.0 parts of accelerator 2-mercaptobenzothiazole.

[0030] In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically includes the following steps: After grinding the pyrolytic carbon black, mix it with nitric acid solution at a weight ratio of 1:20, the pH of the acid solution is 3.0, and react at 40 °C with stirring for 2 h; 4 wt% water glass solution was added dropwise into the mixed solution formed in the above steps under stirring, and the mixture was stirred for reaction for 10 hours, filtered, washed and dried to obtain SiO2-CBp, wherein the weight ratio of water glass to pyrolytic carbon black was 1.0:10; The SiO2-CBp was ultrasonically dispersed in a 2wt% ‌Tween-60 aqueous solution, heated to 70°C, paraffin was added, ultrasonically dispersed for 20 min, cooled to room temperature, filtered, washed and dried; The dried product was transferred to a 4-fold weight ethanol-water solution (the volume ratio of ethanol to water was 1:1), PE6800 was added and stirred for 10 hours, and after washing with petroleum ether, it was filtered, washed with water and ethanol, and dried to obtain the product; the weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin was 10:0.8:50:40.

[0031] Modified starch is prepared by the following steps: Dissolve carboxymethyl starch in 3 times the weight of 15% vol ethanol aqueous solution, add sodium hydroxide and stir for 30 minutes, then add benzoyl chloride, heat to 35°C, react for 30-40 minutes, neutralize with glacial acetic acid to neutrality, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0032] Comparative Example 1 Comparative Example 1 is a comparative example of Example 4, and differs from Example 1 in that: Comparative Example 1 adopts dry mixing process: First, pyrolytic carbon black and natural latex are added to the internal mixer, and then epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant are added for mixing. The initial temperature is 90°C, the rotor speed is 80r, and the mixing is 6min; the mixture enters the open mixer, the roller distance of the open mixer is set to 2mm, the roller is passed three times, and then the minimum roller distance is adjusted for thin pass. When the rubber is wrapped around the roller, accelerator and sulfur are added, and the rubber is cut to make the rubber dispersed evenly. After rolling three times, the roller distance is adjusted to 3mm for sheeting; vulcanization: the vulcanization conditions are 150°C, 10MPa, and the time t 90 *1.3, get composite glue.

[0033] The ingredients are calculated in parts by weight: 60 parts of pyrolytic carbon black and natural latex in total (the weight ratio of natural latex dry rubber to pyrolytic carbon black is 1:0.7), 21 parts of epoxidized natural rubber, 5 parts of modified starch, 5 parts of microcrystalline cellulose, 1.5 parts of zinc oxide, 0.8 parts of antioxidant RD, 0.7 parts of sulfur, and 1.0 parts of accelerator 2-mercaptobenzothiazole.

[0034] Comparative Example 2 The difference between Comparative Example 2 and Example 4 is that the pyrolytic carbon black in Comparative Example 2 has not been surface treated, and the other processes are the same as those in Example 4.

[0035] Comparative Example 3 The difference between Comparative Example 3 and Example 4 is that the pyrolytic carbon black is only subjected to the first step of acid treatment, that is, the pyrolytic carbon black is subjected to surface pretreatment in step (1), which specifically includes the following steps: The pyrolytic carbon black was ground and mixed with nitric acid solution at a weight ratio of 1:20. The pH of the acid solution was 3.0. The mixture was stirred at 40°C for 2 h and then washed and dried to obtain the product.

[0036] Comparative Example 4 The difference between Comparative Example 4 and Example 4 is that the pyrolytic carbon black is surface treated in the first two steps, and specifically comprises the following steps: After grinding the pyrolytic carbon black, mix it with nitric acid solution at a weight ratio of 1:20, the pH of the acid solution is 3.0, and react at 40 °C with stirring for 2 h; Under stirring, add 4wt% water glass solution drop by drop into the mixed solution formed in the above steps, stir and react for 10 hours, filter, wash and dry to obtain the product, the weight ratio of water glass to pyrolytic carbon black is 1.0:10.

[0037] Performance Testing The comprehensive mechanical properties of the composite adhesives prepared in Examples 1-4 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0038] Table 1 Performance test results It can be seen from Table 1 that the composite adhesive prepared by the wet process in Examples 1-4 of the present application has high hardness, excellent mechanical properties and wear resistance.

[0039] Combining Comparative Examples 1-4, it can be seen that Comparative Example 1 adopts a dry mixing process, and its overall mechanical properties are lower than the wet process of Example 4, indicating that the pyrolytic carbon black of the present application is more suitable for wet preparation, and its dispersibility is better in the wet preparation process, and the reinforcement effect is more excellent. Combining Comparative Examples 2-4, it can be seen that the pyrolytic carbon black in Comparative Example 2 has not been surface treated, and its hardness, 100% / 300% tensile stress, tensile strength and elongation at break are much lower than those of Example 4, and the wear amount is relatively large, indicating that the surface treatment process of the pyrolytic carbon black of the present application greatly improves the overall performance of the composite rubber. At the same time, referring to the data of Comparative Examples 3-4, it can be seen that the pickling process can improve the wear resistance of the composite rubber, and after pickling, the surface area of ​​its particle size increases, the interface strength with the rubber increases, and its mechanical properties are also improved to a certain extent; and after silica loading, its mechanical properties can be further improved. Finally, the pyrolytic carbon black after amphiphilic modification is not only fully dispersed in the natural latex in the wet process, but also can be more evenly distributed in the rubber in the mixing stage, and its mechanical properties and wear resistance are greatly improved.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A process for wet mixing of pyrolytic carbon black composite rubber, characterized in that: The following steps are involved: (1) dispersing pyrolytic carbon black in water to form a liquid dispersion; (2) Dispersing natural rubber latex uniformly in water, mixing it uniformly with the liquid phase dispersion, and then flocculating it. The flocculent is washed, dehydrated, and dried to obtain a wet masterbatch. (3) Mixing the wet masterbatch and the additives according to the ingredients and vulcanizing them to obtain the composite rubber; In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically comprises the following steps: After grinding the pyrolytic carbon black, disperse it in an acid solution with a pH of 2.0-3.0 and stir it at 40 °C for 2 h; The water glass solution is added drop by drop into the mixed solution formed in the above steps under stirring, and the mixture is stirred for reaction for 8-10 hours. The product is filtered, washed and dried to obtain SiO2-CBp, and the weight ratio of the water glass to the pyrolytic carbon black is 0.5-1:

10.

2. The process for wet mixing of pyrolytic carbon black composite rubber according to claim 1, characterized in that: In the step (2), the weight ratio of natural rubber latex dry rubber to pyrolytic carbon black is 1:0.6-0.

7.

3. The process for wet mixing of pyrolytic carbon black composite rubber according to claim 1, characterized in that: Surface preparation also includes the following steps: Ultrasonic dispersion of SiO2-CBp in 1-2wt% ‌Tween-60 aqueous solution, heating to 70°C, adding paraffin, ultrasonic dispersion for 20 min, cooling to room temperature, filtering, washing and drying; The dried product was transferred to an ethanol-water solution, PE6800 was added, stirred and reacted for 10 h, washed with petroleum ether, filtered, washed with water and ethanol, and dried to obtain the product; The weight ratio of the SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin is 10:0.5-0.8:50:30-40.

4. The process for wet mixing of pyrolytic carbon black composite rubber according to claim 1, characterized in that: The ingredients of step (3) are calculated by weight: 60 parts of wet masterbatch, 15-21 parts of epoxidized natural rubber, 3-5 parts of modified starch, 3-5 parts of microcrystalline cellulose, 1.0-1.5 parts of zinc oxide, 0.7-0.8 parts of antioxidant RD, 0.5-0.7 parts of sulfur, and 0.8-1.0 parts of accelerator 2-mercaptobenzothiazole.

5. The process for wet mixing of pyrolytic carbon black composite rubber according to claim 4, characterized in that: The modified starch is prepared by the following steps: Dissolve carboxymethyl starch in an appropriate amount of 15% ethanol aqueous solution, add sodium hydroxide and stir for 30 minutes, then add benzoyl chloride, heat to 35°C, react for 30-40 minutes, adjust to neutral with acid, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:

2.

6. The process for wet mixing of pyrolytic carbon black composite rubber according to claim 4, characterized in that: In the step (3), the wet masterbatch is first added to an internal mixer, and epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant are added for mixing, with the initial temperature at 90°C and mixing for 6 minutes; the mixture is put into an open mixer, the roller spacing of the open mixer is set to 2 mm, the mixture is rolled three times, and then the minimum roller spacing is adjusted for thin pass, and an accelerator and sulfur are added when the rubber is rolled, and after rolling three times, the roller spacing is adjusted to 3 mm for sheeting; vulcanization: the vulcanization conditions are 150°C and 10MPa.

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