A process for wet mixing composite rubber of pyrolytic carbon black

Abstract

The present invention discloses a process for wet mixing composite rubber of pyrolytic carbon black, which relates to the technical field of wet rubber mixing and comprises the following steps: (1) dispersing pyrolytic carbon black in water to form a liquid-phase dispersion; (2) uniformly dispersing natural latex in water, mixing it with the liquid-phase dispersion evenly and then carrying out flocculation, washing, dehydrating and drying the floccules to obtain wet masterbatch; (3) mixing and vulcanizing the wet masterbatch and additives according to the formula to obtain composite rubber. In this process, the pyrolytic carbon black undergoes surface treatment in three steps, has strong stability in rubber, and greatly improves the mechanical properties and wear resistance of the composite rubber.

Description

Technical Field

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

[0002] Waste tires are mainly composed of 60 - 65% rubber, 20 - 35% carbon black, and some additives. During the processing of tires, cross - linking reactions occur among elastomers, sulfur, and the host in the rubber, forming insoluble cross - linked elastomers with high strength and elasticity, which are not easily decomposed. Therefore, waste tires not only have a large volume but are also not easily biodegradable naturally, being one of the largest sources of solid waste. Recycling and reusing waste tires is of great significance for realizing circular economy and intensive resource utilization.

[0003] Currently, the most common recycling method for waste tires is waste tire pyrolysis. Through the heating process, chemical bonds in the rubber material can be broken, and finally decomposed into pyrolysis gas, pyrolysis oil, and pyrolytic carbon black, etc., thereby realizing resource reuse. Pyrolytic carbon black can be reapplied as a reinforcing material in rubber products.

[0004] Currently, when pyrolytic carbon black is used for rubber reinforcement, the main problems are as follows: 1. During the pyrolysis process, hydrocarbon molecules in the rubber adsorb on the surface of pyrolytic carbon black and adhere to some coke - like substances, resulting in relatively large aggregates. Moreover, due to the uneven distribution of rubber compounds, carbon black, etc. in waste tires, the particle size distribution of pyrolytic carbon black is uneven; 2. After pyrolysis, the surface functional groups of pyrolytic carbon black decrease and its activity is low, affecting its dispersibility and stability in rubber; 3. The currently commonly used surface modification methods are pickling or surface modification with coupling agents. The problems with this modification method are that after pickling, the surface of pyrolytic carbon black is etched and its reinforcement performance deteriorates. In addition, when using coupling agents for modification, although it can improve the classification performance of pyrolytic carbon black, the functional groups of the coupling agent have a relatively large volume, affecting the combination of pyrolytic carbon black and rubber, resulting in poor wear resistance of the rubber. Summary of the Invention

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

[0006] To achieve the above - mentioned purpose, the present invention adopts the following technical solutions:

[0007] A process for wet mixing composite rubber with pyrolytic carbon black, comprising the following steps:

[0008] (1) Dispersing pyrolytic carbon black in water to form a liquid - phase dispersion;

[0009] (2) Uniformly disperse natural latex in water, mix it evenly with the liquid-phase dispersion, and then carry out flocculation. Wash, dehydrate, and dry the flocs to obtain wet-process masterbatch rubber;

[0010] (3) Knead and vulcanize the wet-process masterbatch rubber and additives according to the formula to obtain compound rubber;

[0011] In the step (1), the pyrolytic carbon black undergoes surface pretreatment, which specifically includes the following steps:

[0012] After grinding the pyrolytic carbon black, disperse it in an acid solution with a pH of 2.0 - 3.0, and stir at 40 °C for 2 h;

[0013] Dropwise add the sodium silicate solution into the mixed solution formed in the above step under stirring, stir and react for 8 - 10 h, filter, wash, and dry the product to obtain SiO2-CBp. The weight ratio of sodium silicate to pyrolytic carbon black is 0.5 - 1:10.

[0014] Furthermore, in the step (2), the weight ratio of the dry rubber of natural latex to pyrolytic carbon black is 1:0.6 - 0.7.

[0015] Furthermore, the surface pretreatment also includes the following steps:

[0016] Ultrasonically disperse SiO2-CBp in a 1 - 2 wt% Tween-60 aqueous solution, heat up to 70 °C, add paraffin, ultrasonically disperse for 20 min, cool to room temperature, filter, wash, and dry;

[0017] Transfer the dried product to an ethanol-aqueous solution, add PE6800 and stir and react for 10 h, wash with petroleum ether, filter, then wash with water and ethanol, and dry to obtain the product;

[0018] The weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution, and paraffin is 10:0.5 - 0.8:50:30 - 40.

[0019] Furthermore, the formula in the step (3) is as follows by weight: 60 parts of wet-process masterbatch rubber, 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, 0.8 - 1.0 parts of accelerator 2-mercaptobenzothiazole.

[0020] Furthermore, the modified starch is prepared by the following steps:

[0021] Dissolve carboxymethyl starch in an appropriate amount of 15% ethanol aqueous solution, add sodium hydroxide and stir for 30 min, then add benzoyl chloride, raise the temperature to 35 °C, react for 30 - 40 min, adjust to neutral with acid, precipitate the product with ethanol, filter, wash and dry to obtain modified starch; the molar ratio of carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0022] Further, in the step (3), first add the wet masterbatch to a mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing, with an initial temperature of 90 °C and mixing for 6 min; enter an open mill, set the roll gap of the open mill to 2 mm, pass through the rolls three times, then adjust the minimum roll gap for thin passing, add accelerator and sulfur when the rubber stock wraps around the roll, after rolling three times, adjust the roll gap to 3 mm and take off the sheet; vulcanization: the vulcanization conditions are 150 °C and 10 MPa.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention discloses a process for preparing a pyrolytic carbon black wet mixing composite rubber. Through three steps of surface treatment of waste tire pyrolytic carbon black and then adopting a wet mixing process, modified starch and microcrystalline cellulose are also added as reinforcing fillers in the formulation, and the modified starch is a modified amphiphilic starch. Therefore, these reinforcing fillers such as pyrolytic carbon black, modified starch and microcrystalline cellulose can be uniformly dispersed in the rubber and form a strong interaction with the rubber, thus greatly increasing the mechanical properties and wear resistance of the composite rubber.

[0025] 2. The pyrolytic carbon black in this application adopts a three-step surface treatment process; since the surface of pyrolytic carbon black contains a large amount of carbonaceous or ash components, in this application, acid pickling and etching are first used to reduce the ash content and increase the surface area, and then water glass solution is dropped. Under acidic conditions, the water glass solution forms a complex (SiO2-CBp) of silicon dioxide deposited on the surface of pyrolytic carbon black, which can improve the surface strength of pyrolytic carbon black and increase its reinforcing performance. Since SiO2-CBp after silicon dioxide surface loading is hydrophilic and can be uniformly dispersed in water, it is more suitable for wet mixing.

[0026] However, due to the relatively large number of surface functional groups such as hydroxyl groups on its surface and its relatively high surface free energy, its dispersion performance in rubber during the mixing process is relatively poor, which is likely to affect the mechanical strength of vulcanized rubber. Therefore, in this application, further surface treatment is carried out on SiO2-CBp after loading silicon dioxide. First, part of its surface is protected with paraffin, and then it is modified with PE6800. After removing the paraffin, an amphiphilic structure is formed, which can be uniformly dispersed during the wet process and can also be uniformly distributed in the rubber through hydrogen bonding, hydrophobic interaction and electrostatic interaction during the subsequent mixing process, greatly increasing the mechanical properties of the mixing rubber in this application. Specific embodiments

[0027] The present invention will be further described below in conjunction with specific embodiments.

[0028] Example 1

[0029] A process for wet mixing composite rubber of pyrolytic carbon black includes the following steps:

[0030] (1) Mix pyrolytic carbon black and water to form a 25% liquid-phase dispersion;

[0031] (2) Uniformly disperse natural rubber latex (solid content 60%) in water, mix it evenly with the liquid-phase dispersion, then drop 5 wt% calcium chloride for flocculation. The floccules are washed, dehydrated, and dried to obtain wet masterbatch rubber. The weight ratio of dry rubber of natural rubber latex to pyrolytic carbon black is 1:0.6;

[0032] (3) First, add the wet masterbatch rubber into a mixer, and add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide, and antioxidant for mixing. The initial temperature is 90 °C, the rotor speed is 80 r, and the mixing time is 6 min; then transfer to an open mill. The roll gap of the open mill is set to 2 mm, pass through the rolls three times, and then adjust to the minimum roll gap for thin passing. When the rubber compound wraps around the roll, add accelerator and sulfur, and cut the rubber compound to make it disperse evenly. After passing through the rolls three times, adjust the roll gap to 3 mm and take off the sheet; Vulcanization: The vulcanization conditions are 150 °C, 10 MPa, and the time is t 90 *1.3 (1.3 times the optimum vulcanization time) to obtain the composite rubber.

[0033] Among them, the above mixing ingredients are in parts by weight: 60 parts of wet masterbatch rubber, 15 parts of epoxidized natural rubber, 3 parts of modified starch, 3 parts of microcrystalline cellulose, 1.0 part of zinc oxide, 0.7 part of antioxidant RD, 0.5 part of sulfur, and 0.8 part of accelerator 2-mercaptobenzothiazole.

[0034] In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which is specifically prepared by the following steps:

[0035] 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 and react at 40 °C for 2 h;

[0036] While stirring, gradually drop 4 wt% sodium silicate solution into the mixed solution formed in the above step, stir and react for 8 h, filter, wash, and dry to obtain SiO2-CBp. The weight ratio of sodium silicate to pyrolytic carbon black is 0.5:10;

[0037] Ultrasonically disperse SiO2-CBp in 1.5 wt% Tween-60 aqueous solution, heat up to 70 °C, add paraffin, ultrasonically disperse for 20 min, cool to room temperature, filter, wash, and dry;

[0038] Transfer the dried product into an ethanol - aqueous solution with a weight 4 times that of the product (the volume ratio of ethanol to water is 1:1), add PE6800 and stir for 10 h. After washing with petroleum ether to remove the paraffin, filter, and then wash with water and ethanol, and dry to obtain the product; the weight ratio of SiO2 - CBp, PE6800, aqueous Tween - 60 solution and paraffin is 10:0.5:50:30.

[0039] The modified starch is prepared by the following steps:

[0040] Dissolve carboxymethyl starch in an ethanol - aqueous solution with a volume fraction of 15% and a weight 3 times that of the carboxymethyl starch, add sodium hydroxide and stir for 30 min, then add benzoyl chloride, raise the temperature to 35 °C, react for 30 - 40 min, neutralize to neutral with glacial acetic acid, precipitate the product with ethanol, filter, wash and dry to obtain the modified starch; the molar ratio of carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0041] Example 2

[0042] A process for wet - mixing composite rubber of pyrolytic carbon black includes the following steps:

[0043] (1) Mix pyrolytic carbon black and water to form a 25% liquid - phase dispersion;

[0044] (2) Uniformly disperse natural rubber latex (solid content 60%) in water, mix it evenly with the liquid - phase dispersion, then drop 5 wt% calcium chloride for flocculation. Wash, dehydrate and dry the floccules to obtain wet - mixing masterbatch. The weight ratio of dry rubber of natural rubber latex to pyrolytic carbon black is 1:0.65;

[0045] (3) First, add the wet - mixing masterbatch into a mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing. The initial temperature is 90 °C, the rotor speed is 80 r, and mix for 6 min; transfer to an open mill, set the roll gap of the open mill to 2 mm, pass through the rolls three times, then adjust to the minimum roll gap for thin - passing. When the rubber compound wraps around the roll, add accelerator and sulfur, and cut the rubber compound to make it disperse evenly. After passing through the rolls three times, adjust the roll gap to 3 mm and take off the sheet; Vulcanization: The vulcanization conditions are 150 °C, 10 MPa, and time t 90 *1.3 to obtain the composite rubber.

[0046] Among them, the ingredients are in parts by weight: 60 parts of wet - mixing 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 part of antioxidant RD, 0.6 part of sulfur, 0.9 part of accelerator 2 - mercaptobenzothiazole.

[0047] In step (1), the pyrolytic carbon black undergoes surface pretreatment, which is specifically prepared by the following steps:

[0048] After grinding the pyrolytic carbon black, it was mixed with a nitric acid solution at a weight ratio of 1:20. The pH of the nitric acid solution was 2.5, and the mixture was stirred and reacted at 40 °C for 2 h;

[0049] Under stirring, a 4 wt% sodium silicate solution was gradually dropped into the mixed solution formed in the above step, and the mixture was stirred and reacted for 8 h. After filtration, washing and drying, SiO2-CBp was obtained. The weight ratio of sodium silicate to pyrolytic carbon black was 0.6:10;

[0050] SiO2-CBp was ultrasonically dispersed in a 1.5 wt% Tween-60 aqueous solution. The temperature was raised to 70 °C, paraffin was added, and the mixture was ultrasonically dispersed for 20 min. Then it was cooled to room temperature, filtered, washed and dried;

[0051] The dried product was transferred to an ethanol-aqueous solution with a weight 4 times that of the product (the volume ratio of ethanol to water was 1:1). PE6800 was added and the mixture was stirred and reacted for 10 h. After washing with petroleum ether, filtration was carried out, and then washing with water and ethanol was performed, followed by drying to obtain the product; the weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution and paraffin was 10:0.6:50:30.

[0052] The modified starch was prepared by the following steps:

[0053] The carboxymethyl starch was dissolved in a 15% vol ethanol-aqueous solution with a weight 3 times that of the carboxymethyl starch. Sodium hydroxide was added and stirred for 30 min, then benzoyl chloride was added. The temperature was raised to 35 °C and the reaction was carried out for 30 - 40 min. It was neutralized to neutral with glacial acetic acid, and the product was precipitated with ethanol, filtered, washed and dried to obtain the modified starch; the molar ratio of the carboxymethyl starch, benzoyl chloride and sodium hydroxide was 1:2:2.

[0054] Example 3

[0055] A process for preparing a wet-mixing composite rubber of pyrolytic carbon black, comprising the following steps:

[0056] (1) Mix pyrolytic carbon black and water to form a 25% liquid-phase dispersion;

[0057] (2) Uniformly disperse natural rubber latex (solid content 60%) in water, mix it evenly with the liquid-phase dispersion, and then drop 5 wt% calcium chloride for flocculation. The floccules were washed, dehydrated and dried to obtain the wet masterbatch. The weight ratio of the dry rubber of natural rubber latex to pyrolytic carbon black was 1:0.7;

[0058] (3) First, add the wet masterbatch into a mixer, and add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide, and antioxidant for mixing. The initial temperature is 90 °C, the rotor speed is 80 r, and the mixing time is 6 min. Then transfer to an open mill. The roll gap of the open mill is set to 2 mm, pass through the rolls three times, and then adjust to the minimum roll gap for thin passing. When the rubber compound wraps around the roll, add accelerator and sulfur, and cut the rubber compound to make it disperse evenly. After passing through the rolls three times, adjust the roll gap to 3 mm and take off the sheet. Vulcanization: The vulcanization conditions are 150 °C, 10 MPa, and time t 90 *1.3 to obtain the composite rubber.

[0059] Among them, the ingredients are 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 part of antioxidant RD, 0.7 part of sulfur, and 0.9 part of accelerator 2-mercaptobenzothiazole.

[0060] In step (1), the pyrolytic carbon black is surface pretreated, and the specific preparation steps are as follows:

[0061] After grinding the pyrolytic carbon black, mix it with an acid solution at a weight ratio of 1:20. The pH of the acid solution is 2.5, and stir and react at 40 °C for 2 h;

[0062] While stirring, gradually drop a 4 wt% sodium silicate solution into the mixed solution formed in the above step, stir and react for 9 h, filter, wash, and dry to obtain SiO2-CBp. The weight ratio of sodium silicate to pyrolytic carbon black is 0.8:10;

[0063] Disperse SiO2-CBp ultrasonically in a 1.5 wt% Tween-60 aqueous solution, heat up to 70 °C, add paraffin, ultrasonically disperse for 20 min, cool to room temperature, filter, wash, and dry;

[0064] Transfer the dried product to a 5-fold weight ethanol-aqueous solution (the volume ratio of ethanol to water is 1:1), add PE6800 and stir and react for 10 h. After washing with petroleum ether, filter, and then wash with water and ethanol, and dry to obtain the product; the weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution, and paraffin is 10:0.7:50:40.

[0065] The modified starch is prepared by the following steps:

[0066] Dissolve carboxymethyl starch in a 3-fold weight 15% vol ethanol-aqueous solution, add sodium hydroxide and stir for 30 min, then add benzoyl chloride, heat up to 35 °C, react for 30 - 40 min, neutralize to neutral with glacial acetic acid, precipitate the product with ethanol, filter, wash, and dry to obtain the modified starch; the molar ratio of carboxymethyl starch, benzoyl chloride, and sodium hydroxide is 1:2:2.

[0067] Example 4

[0068] A process for preparing a wet-mixed composite rubber of pyrolytic carbon black includes the following steps:

[0069] (1) Mix pyrolytic carbon black and water to form a 25% liquid-phase dispersion;

[0070] (2) Uniformly disperse natural latex (solid content 60%) in water, mix it evenly with the liquid-phase dispersion, then drop 5 wt% calcium chloride for flocculation. The floccules are washed, dehydrated, and dried to obtain a wet masterbatch. The weight ratio of the dry rubber of natural latex to pyrolytic carbon black is 1:0.7;

[0071] (3) First, add the wet masterbatch into a mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide, and antioxidant for mixing. The initial temperature is 90 °C, the rotor speed is 80 r, and the mixing time is 6 min; then transfer it to an open mill. The roll gap of the open mill is set to 2 mm, pass through the rolls three times, then adjust the minimum roll gap for thin-sheeting. When the rubber stock wraps around the roll, add accelerator and sulfur, and cut the rubber stock to make it disperse evenly. After passing through the rolls three times, adjust the roll gap to 3 mm and take off the sheet; Vulcanization: The vulcanization conditions are 150 °C, 10 MPa, and time t 90 *1.3, to obtain the composite rubber.

[0072] Among them, the ingredients are in parts 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 part of antioxidant RD, 0.7 part of sulfur, and 1.0 part of accelerator 2-mercaptobenzothiazole.

[0073] In step (1), the pyrolytic carbon black is subjected to surface pretreatment, which is specifically prepared by the following steps:

[0074] After grinding the pyrolytic carbon black, mix it with a nitric acid solution at a weight ratio of 1:20. The pH of the acid solution is 3.0, and stir and react at 40 °C for 2 h;

[0075] While stirring, gradually drop a 4 wt% sodium silicate solution into the mixed solution formed in the above step, stir and react for 10 h, filter, wash, and dry to obtain SiO2-CBp. The weight ratio of sodium silicate to pyrolytic carbon black is 1.0:10;

[0076] Ultrasonically disperse SiO2-CBp in a 2 wt% Tween-60 aqueous solution, heat up to 70 °C, add paraffin, ultrasonically disperse for 20 min, cool to room temperature, filter, wash, and dry;

[0077] Transfer the dried product into an ethanol - aqueous solution with a weight 4 times that of the product (the volume ratio of ethanol to water is 1:1), add PE6800 and stir for reaction for 10 h. After washing with petroleum ether, filter, then wash with water and ethanol, and dry to obtain the product; the weight ratio of SiO2 - CBp, PE6800, aqueous solution of Tween - 60 and paraffin is 10:0.8:50:40.

[0078] The modified starch is prepared by the following steps:

[0079] Dissolve carboxymethyl starch in an ethanol aqueous solution with a weight 3 times that of the starch and a volume fraction of 15%, add sodium hydroxide and stir for 30 min, then add benzoyl chloride, raise the temperature to 35 °C, react for 30 - 40 min, neutralize to neutral with glacial acetic acid, precipitate the product with ethanol, filter, wash and dry to obtain the modified starch; the molar ratio of carboxymethyl starch, benzoyl chloride and sodium hydroxide is 1:2:2.

[0080] Comparative Example 1

[0081] Comparative Example 1 is a comparative example of Example 4, and the difference from Example 1 is that:

[0082] Comparative Example 1 adopts a dry - mixing process:

[0083] First, add pyrolytic carbon black and natural latex into a mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide and antioxidant for mixing. The initial temperature is 90 °C, the rotor speed is 80 r, and mix for 6 min; then transfer to an open mill, set the roll gap of the open mill to 2 mm, pass through the rolls three times, then adjust the minimum roll gap for thin - passing. When the rubber compound wraps around the roll, add accelerator and sulfur, and cut the rubber compound to make it disperse evenly. After passing through the rolls three times, adjust the roll gap to 3 mm and take off the sheet; vulcanization: the vulcanization conditions are 150 °C, 10 MPa, and the time is t 90 *1.3 to obtain the composite rubber.

[0084] Among them, the ingredients are in parts by weight: the total of pyrolytic carbon black and natural latex is 60 parts (the weight ratio of dry natural rubber latex to pyrolytic carbon black is 1:0.7), epoxidized natural rubber 21 parts, modified starch 5 parts, microcrystalline cellulose 5 parts, zinc oxide 1.5 parts, antioxidant RD 0.8 parts, sulfur 0.7 parts, accelerator 2 - mercaptobenzothiazole 1.0 part.

[0085] Comparative Example 2

[0086] The difference between Comparative Example 2 and Example 4 is that the pyrolytic carbon black in Comparative Example 2 is not surface - treated, and other processes are the same as those in Example 4.

[0087] Comparative Example 3

[0088] The difference between Comparative Example 3 and Example 4 is that the pyrolytic carbon black only undergoes the first - step acid treatment, that is: in step (1), the pyrolytic carbon black undergoes surface pretreatment, which is specifically prepared by the following steps:

[0089] After grinding the pyrolytic carbon black, it is mixed with a nitric acid solution at a weight ratio of 1:20. The pH of the acid solution is 3.0, and it is stirred and reacted at 40 °C for 2 h, then washed and dried to obtain the product.

[0090] Comparative Example 4

[0091] The difference between Comparative Example 4 and Example 4 is that the pyrolytic carbon black undergoes surface treatment in the first two steps, which is specifically prepared by the following steps:

[0092] After grinding the pyrolytic carbon black, it is mixed with a nitric acid solution at a weight ratio of 1:20. The pH of the acid solution is 3.0, and it is stirred and reacted at 40 °C for 2 h;

[0093] While stirring, a 4wt% sodium silicate solution is gradually dropped into the mixed solution formed in the above - mentioned step, stirred and reacted for 10 h, filtered, washed and dried to obtain the product. The weight ratio of sodium silicate to pyrolytic carbon black is 1.0:10.

[0094] Performance detection

[0095] The comprehensive mechanical properties of the composite rubbers prepared in Examples 1 - 4 and Comparative Examples 1 - 4 were detected, and the results are shown in Table 1.

[0096] Table 1 Performance detection results

[0097]

[0098] As can be seen from Table 1, the composite rubbers prepared by the wet - process in Examples 1 - 4 of the present application have high hardness, excellent mechanical properties and wear resistance.

[0099] It can be seen from Comparative Examples 1-4 that in Comparative Example 1, a dry mixing process was used, and its overall mechanical properties were lower than those of the wet process in Example 4, indicating that the pyrolytic carbon black of the present application is more suitable for wet preparation, with better dispersibility and more excellent reinforcement effect in the wet preparation process. It can be seen from Comparative Examples 2-4 that the pyrolytic carbon black in Comparative Example 2 was not surface-treated, and its hardness, 100% / 300% modulus at 100% / 300% elongation, tensile strength, and elongation at break were far lower than those in Example 4, and the wear amount was 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 in Comparative Examples 3-4, it can be seen that the pickling process can improve the wear resistance of the composite rubber, and after pickling, its particle size surface area increases, the interfacial strength with rubber increases, and its mechanical properties are also improved to a certain extent; after being loaded with silica, its mechanical properties can be further improved. Finally, the pyrolytic carbon black after amphiphilic modification can not only be fully dispersed in natural latex in the wet process, but also be more evenly distributed in rubber during the mixing stage, and its mechanical properties and wear resistance are greatly improved.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention shall be covered by the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for wet mixing and compounding pyrolytic carbon black, characterized in that: It includes the following steps: (1) Disperse pyrolytic carbon black in water to form a liquid-phase dispersion; (2) Uniformly disperse natural latex in water, mix it evenly with the liquid-phase dispersion, then perform flocculation. The flocs are washed, dehydrated, and dried to obtain wet-process masterbatch rubber; (3) Knead and vulcanize the wet-process masterbatch rubber and additives according to the formulation to obtain compound rubber; In the step (1), the pyrolytic carbon black is subjected to surface pretreatment, which specifically includes 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 at 40 °C for 2 h; Dropwise add the sodium silicate solution into the mixed solution formed in the above step under stirring, stir and react for 8 - 10 h, filter, wash, and dry the product to obtain SiO2-CBp. The weight ratio of sodium silicate to pyrolytic carbon black is 0.5 - 1:10; Ultrasonically disperse SiO2-CBp in a 1 - 2 wt% Tween-60 aqueous solution, heat up to 70 °C, add paraffin, ultrasonically disperse for 20 min, cool to room temperature, filter, wash, and dry; Transfer the dried product to an ethanol-aqueous solution, add PE6800 and stir and react for 10 h, wash with petroleum ether, filter, then wash with water and ethanol, and dry to obtain the product; The weight ratio of SiO2-CBp, PE6800, Tween-60 aqueous solution, and paraffin is 10:0.5 - 0.8:50:30 - 40.

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

7.

3. The process of a wet mixing composite rubber of pyrolytic carbon black according to claim 1, characterized in that: The formulation in the step (3) is by weight: 60 parts of wet-process masterbatch rubber, 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, 0.8 - 1.0 parts of accelerator 2-mercaptobenzothiazole.

4. A process for wet mixing and compounding a pyrolytic carbon black, according to claim 3, 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 min, then add benzoyl chloride, heat up to 35 °C, react for 30 - 40 min, adjust to neutral with acid, precipitate the product with ethanol, filter, wash, and dry to obtain modified starch; the molar ratio of carboxymethyl starch, benzoyl chloride, and sodium hydroxide is 1:2:

2.

5. The process for preparing a pyrolytic carbon black wet mixing composite rubber according to claim 3, characterized in that: In the step (3), first add the wet-process masterbatch rubber into a mixer, add epoxidized natural rubber, modified starch, microcrystalline cellulose, zinc oxide, and antioxidant for kneading. The initial temperature is 90 °C, and knead for 6 min; enter an open mill, set the roll gap of the open mill to 2 mm, pass through the rolls three times, then adjust the minimum roll gap for thin passing. When the rubber compound wraps around the roll, add the accelerator and sulfur, roll three times, then adjust the roll gap to 3 mm and take off the sheet; Vulcanization: The vulcanization conditions are 150 °C, 10 MPa.

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