Smoked particulate natural rubber, method of preparation and use, rubber composite

Abstract

The application provides a smoked granular natural rubber, a preparation method and application thereof, and a rubber composite, and belongs to the technical field of natural rubber processing. Natural rubber latex is mixed with a coagulant to be coagulated, and then crepe and granulation are sequentially performed to obtain rubber wet particles, the particle size of the rubber wet particles is 2-50 mm, and the stacking thickness is 5-100 cm; the rubber wet particles are subjected to smoking treatment to obtain smoked rubber wet particles; and the smoked rubber wet particles are dried to obtain the smoked granular natural rubber. The application takes advantage of the large specific surface area of the rubber wet particles to improve the smoking contact reaction efficiency, increases the active sites of the rubber molecular chains, makes the reaction between the proteins or phospholipids in the natural rubber and the phenols and carbonyl compounds in the smoking gas more uniform, solves the technical problem of uneven smoking reaction of traditional hanging piece rubber, and realizes the decrease of the long chain branching degree of the natural rubber and the widening of the molecular weight distribution index.

Description

Technical Field

[0001] This invention relates to the field of natural rubber processing technology, and in particular to a smoked granulated natural rubber, its preparation method and application, and rubber composite materials. Background Technology

[0002] Natural rubber is a natural polymer compound with cis-1,4-polyisoprene as its main component. The non-rubber components such as proteins and phospholipids bound in its molecular chain are the important basis for the branched structure of rubber molecules. With its excellent elasticity, mechanical strength, flexural resistance and processing adaptability, it has become the core raw material for the production of rubber products such as tires, hoses, rubber seals, and shoe soles, and occupies an irreplaceable position in industrial manufacturing, transportation and other fields.

[0003] Smoking is a key modification process in natural rubber processing. The active components such as phenols and carbonyl compounds in the smoke produced by wood distillation can react with non-rubber components in natural rubber, regulating the topological structure of rubber molecules and improving the rubber's aging resistance and antibacterial properties. Traditional smoking processes mainly target sheet rubber. For example, existing technologies disclose a method to improve the processing performance of natural rubber by pressing solidified rubber into thin sheets and suspending them for smoking. This process has significant technical drawbacks: First, the sheet rubber has a small specific surface area, limiting the contact area between the smoke and the rubber, resulting in insufficient and uneven reaction between the active components and proteins and phospholipids in the rubber. Second, the preparation of sheet rubber lacks strong mechanical shearing action, resulting in few active sites on the rubber molecular chains, making it difficult to effectively regulate the long-chain branched structure. Third, the inherent problem of excessively high long-chain branching in natural rubber remains unresolved, leading to high processing viscosity and poor dispersion of fillers such as carbon black, thus reducing the overall mechanical properties of the rubber products. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a smoked granulated natural rubber, its preparation method and application, and rubber composite materials. The smoked granulated natural rubber obtained by this invention has low long-chain branching degree and a wide molecular weight distribution index.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing smoked granular natural rubber, comprising the following steps: After coagulating the natural rubber latex with a coagulant, the mixture is then creped and granulated in sequence to obtain wet rubber granules. The wet rubber granules have a particle size of 2-50 mm and a bulk thickness of 5-100 cm. The wet rubber granules are subjected to smoking treatment to obtain smoked wet rubber granules. The smoked wet rubber granules are dried to obtain the smoked natural rubber granules.

[0006] Preferably, the particle size of the wet rubber granules is 5~30mm.

[0007] Preferably, the thickness of the wet rubber granules is 10-50 cm.

[0008] Preferably, the smoking treatment is carried out at a temperature of 40~80℃ for 1~8 hours.

[0009] Preferably, the fumigation treatment uses fumigation gas, wherein the fumigation gas contains 10-30 wt% phenolic compounds and 5-15 wt% carbonyl compounds, wherein the phenolic compounds include guaiacol, phenol and 2,4-dimethylphenol, and the carbonyl compounds include acetaldehyde, acetone and furfural compounds.

[0010] Preferably, the smoke is produced by the incomplete combustion of sawdust or oil, and the excess air coefficient during incomplete combustion is <1.0.

[0011] Preferably, the flow rate of the smoke gas during the smoking process is 0.5~2m / s.

[0012] The present invention also provides smoked granular natural rubber prepared by the preparation method described above, wherein the degree of long chain branching of the smoked granular natural rubber is 1.4~2 and the molecular weight distribution index is 3.5~6.0.

[0013] The present invention also provides the application of the smoked granular natural rubber described in the above technical solution in the field of rubber products, wherein the rubber products include engineering tires, aircraft tires, rubber hoses, seals, medical latex products or shoe soles.

[0014] The present invention also provides a rubber composite material comprising the following parts by weight of raw materials: The above technical solution comprises 100 parts of smoked granular natural rubber, 30-60 parts of filler, 4-6 parts of zinc oxide, 1-3 parts of stearic acid, 0.5-1 part of accelerator, and 2-3 parts of sulfur. The filler includes one or more of carbon black, silica, montmorillonite, calcium carbonate, and carbon nanotubes.

[0015] This invention provides a method for preparing smoked granulated natural rubber, comprising the following steps: mixing natural rubber latex with a coagulant and coagulating it, then sequentially creping and granulating it to obtain wet rubber granules, wherein the wet rubber granules have a particle size of 2-50 mm and a bulk thickness of 5-100 cm; subjecting the wet rubber granules to smoke treatment to obtain smoked wet rubber granules; and drying the smoked wet rubber granules to obtain the smoked granulated natural rubber.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention leverages the large specific surface area of ​​wet rubber granules to enhance the efficiency of the fumigation reaction, increasing the active sites on the rubber molecular chains. This results in a more uniform reaction between proteins or phospholipids in natural rubber and phenols and carbonyl compounds in the fumigation gas, solving the technical problem of uneven fumigation reaction in traditional coated rubber. It reduces the branching degree of long-chain rubber, broadens the molecular weight distribution index, and improves the dispersion of carbon black in the rubber compound, thereby enhancing the abrasion resistance of the compound. Furthermore, this invention features a simple and controllable process, stable product quality, and produces fumigated natural rubber granules with excellent overall performance. These granules can be widely used in the production of tires, hoses, and other rubber products, and are easily industrialized and scaled up.

[0017] Furthermore, by adjusting the parameters of the smoking process, the branching structure of natural rubber molecules can be precisely controlled, thereby reducing the branching degree of long chains and broadening the molecular weight distribution index, effectively improving the processing performance of natural rubber.

[0018] Furthermore, the process of this invention is simple and controllable, and the types of coagulants, wood, and oils can be flexibly selected. No new complex processing equipment is required, and it can be achieved by simple modification on existing natural rubber granule production lines. The production cost is low and it is easy to promote industrial-scale production. Detailed Implementation

[0019] This invention provides a method for preparing smoked granular natural rubber, comprising the following steps: After coagulating the natural rubber latex with a coagulant, the mixture is then creped and granulated in sequence to obtain wet rubber granules. The wet rubber granules have a particle size of 2-50 mm and a bulk thickness of 5-100 cm. The wet rubber granules are subjected to smoking treatment to obtain smoked wet rubber granules. The smoked wet rubber granules are dried to obtain the smoked natural rubber granules.

[0020] Unless otherwise specified, all raw materials used in this invention are commercially available products in the field.

[0021] This invention involves mixing natural rubber latex with a coagulant and then coagulating it, followed by creping and granulation to obtain wet rubber granules. The wet rubber granules have a particle size of 2-50 mm and a bulk thickness of 5-100 cm.

[0022] In this invention, the natural rubber latex is fresh natural rubber latex, and the dry rubber content is preferably 20-40 wt%, specifically 20 wt%, 25 wt%, 30 wt%, 35 wt% or 40 wt%, and the nitrogen content is preferably 0.3-0.6%, specifically 0.3%, 0.35%, 0.38%, 0.4%, 0.5% or 0.6%.

[0023] In this invention, the degree of long-chain branching of the natural rubber in the natural rubber latex is preferably 2.12 to 2.35.

[0024] In this invention, the coagulant preferably includes one or more of formic acid, acetic acid, microorganisms, and enzymes. Formic acid and acetic acid are classic acidic chemical coagulants, which have fast coagulation speed and stable effect, and are suitable for the needs of continuous industrial production. Microorganisms and enzymes are natural biological coagulants, which are green and environmentally friendly, have no chemical residues, and have a mild coagulation process that will not damage the structure of rubber molecular chains and non-rubber components. They can be used alone or in combination according to product performance requirements to meet the requirements of different production scenarios.

[0025] The preferred mass ratio of the natural rubber latex to the coagulant, based on the dry rubber mass, is 100:0.8.

[0026] The present invention does not have any special limitations on the crepe, and any method known to those skilled in the art can be used.

[0027] In this invention, the granulation is preferably carried out using a rubber granulator. During the granulation process, the mechanical shearing action can form rubber clumps into particles with uniform particle size, which not only greatly increases the contact area between the rubber and the smoke gas, but also increases the active sites of the rubber molecular chains. The particle size of 2~50mm and the stacking thickness of 5~100cm are matched to ensure that the smoke gas can fully penetrate the rubber particle layer, so that the smoke components can achieve uniform and sufficient contact reaction with the proteins and phospholipids in the rubber particles, while avoiding excessive adsorption of smoke components caused by excessively fine particles and excessively thin stacking, thus ensuring the controllability of the smoke treatment modification effect.

[0028] In this invention, the particle size of the wet rubber particles is preferably 5 to 30 mm, specifically 5, 8, 12, 16, 20, 30, 40 or 45 mm.

[0029] In this invention, the preferred thickness of the wet rubber granules is 10-50 cm, specifically 10, 15, 20, 25, 30, 40 or 50 cm.

[0030] After obtaining the wet rubber granules, the present invention performs a fumigation treatment on the wet rubber granules to obtain fumigated wet rubber granules.

[0031] In this invention, the preferred temperature for the fumigation treatment is 40~80℃, specifically 40, 50, 60, 70 or 80℃, and the preferred time is 1~8h, specifically 1, 2, 3, 4, 5, 6, 7 or 8h. The temperature of the fumigation treatment provides suitable kinetic conditions for the reaction. If the temperature is too low, the reaction rate will be slow and the fumigation time will be too long. If the temperature is too high, it will lead to thermal degradation of rubber molecular chains and non-rubber components, destroying the inherent properties of rubber.

[0032] In this invention, the fumigation treatment preferably uses fumigation gas, wherein the content of phenolic compounds in the fumigation gas is preferably 10-30 wt%, specifically 10 wt%, 20 wt%, 25 wt%, or 30 wt%, and the content of carbonyl compounds is preferably 5-15 wt%, specifically 5 wt%, 8 wt%, 10 wt%, 12 wt%, or 15 wt%. The phenolic compounds preferably include guaiacol, phenol, and 2,4-dimethylphenol, and the carbonyl compounds preferably include acetaldehyde, acetone, and furfural compounds. The phenolic and carbonyl compounds in the fumigation gas are the core active ingredients that react with proteins and phospholipids in rubber. Controlling the content range of active ingredients can fully bind with the active sites of rubber molecular chains, achieving precise control of the long-chain branched structure.

[0033] In this invention, the smoke is preferably generated by the incomplete combustion of wood chips or oil, and the excess air coefficient (α) during incomplete combustion is preferably <1.0, specifically 0.9.

[0034] In this invention, the wood chips preferably include one or more of oak, birch, maple, and pine.

[0035] In this invention, the oil preferably includes one or more of diesel oil, engine oil, gasoline, and lubricating oil.

[0036] In this invention, the flow rate of the fumigation gas during the fumigation treatment is preferably 0.5~2 m / s, specifically 0.5, 0.8, 1, 1.2, 1.5, or 2 m / s. Continuous fumigation is preferred, as it ensures a continuous supply of active ingredients in the fumigation gas, maintaining full contact between the rubber particles and the fumigation gas. This guarantees a complete and uniform reaction between the proteins, phospholipids, and fumigation components in the rubber. The flow rate of 0.5~2 m / s avoids both low production efficiency due to excessively slow flow and insufficient contact time between the fumigation gas and rubber particles due to excessively fast flow, thus ensuring the stability of the fumigation modification effect.

[0037] In this invention, the fumigation treatment is preferably carried out in a fumigation device.

[0038] After obtaining the smoked wet rubber granules, the present invention dries the smoked wet rubber granules to obtain the smoked natural rubber granules.

[0039] In this invention, the drying is preferably hot air drying, and the temperature of the hot air drying is preferably 60~100℃, specifically 60, 70, 80, 90 or 100℃, and the drying time is preferably 8~24h, specifically 8, 12, 15, 16, 20 or 24h. The hot air drying conditions can achieve slow and uniform removal of moisture from the rubber particles, avoiding thermal degradation of the rubber molecular structure caused by excessively high temperature or too short time, while ensuring that the moisture content of the dried rubber particles meets the industrial use standard (preferably 0.5~1.0wt%), so that the product performance is stable. This avoids both excessive moisture causing the rubber to mold and deteriorate during storage and excessive moisture causing the rubber to be brittle during processing.

[0040] This invention also provides smoked granulated natural rubber prepared by the preparation method described in the above technical solution. The degree of long-chain branching of the smoked granulated natural rubber is 1.4~2, specifically 1.48, 1.52, 1.62, 1.78, 1.85 or 1.98, and the molecular weight distribution index is 3.5~6.0, specifically 3.9, 4.1, 4.8 or 5.6. In this invention, the granulation process increases the active sites of the rubber molecular chains, allowing phenols and carbonyl compounds in the smoke to react uniformly and fully with proteins and phospholipids in the rubber, effectively breaking down some of the long-chain branched structures of the natural rubber, reducing the degree of long-chain branching, and simultaneously broadening the molecular weight distribution and optimizing the molecular topology of the rubber.

[0041] The core of this invention lies in: (1) This invention utilizes the advantage of the large specific surface area of ​​granulated rubber to significantly increase the contact area between smoke and rubber. At the same time, the mechanical shearing effect of granulation increases the active sites of rubber molecular chains, making the reaction between the proteins and phospholipids in the rubber and the phenols and carbonyl compounds in the smoke more complete and uniform, thus solving the technical problem of uneven smoke reaction of traditional sheet rubber. (2) By adjusting the granulation parameters and the smoking process parameters, the branching structure of natural rubber molecules can be precisely controlled, thereby reducing the branching degree of the long chain of natural rubber and widening the molecular weight distribution index, which effectively improves the processing performance of natural rubber. (3) The smoked granular natural rubber prepared by the present invention can significantly improve the dispersion and compatibility of carbon black in the rubber compound, thereby improving the comprehensive mechanical properties and wear resistance of rubber products such as tires and hoses, and the product has high application value. (4) The process of this invention is simple and controllable, and the coagulant and wood types can be flexibly selected. No new complex processing equipment is required. It can be achieved by simple modification on the existing natural rubber granule production line. The production cost is low and it is easy to promote industrialization and scale.

[0042] The present invention also provides the application of the smoked granular natural rubber described in the above technical solution in the field of rubber products, wherein the rubber products include engineering tires, aircraft tires, rubber hoses, seals, medical latex products or shoe soles.

[0043] In this invention, the smoked granular natural rubber can significantly improve the dispersion uniformity of fillers (including one or more of carbon black, silica, montmorillonite, calcium carbonate, and carbon nanotubes) in the rubber compound. The natural rubber with reduced long-chain branching and broadened molecular weight distribution has significantly reduced processing viscosity and greatly improved fluidity, providing a good processing foundation for the uniform dispersion of fillers such as carbon black in the rubber compound, thereby improving the comprehensive mechanical properties of rubber products such as tensile strength, flexural strength, and abrasion resistance.

[0044] The present invention also provides a rubber composite material comprising the following parts by weight of raw materials: The above technical solution comprises 100 parts of smoked granular natural rubber, 30-60 parts of filler, 4-6 parts of zinc oxide, 1-3 parts of stearic acid, 0.5-1 part of accelerator, and 2-3 parts of sulfur. The filler includes one or more of carbon black, silica, montmorillonite, calcium carbonate, and carbon nanotubes.

[0045] In this invention, the carbon black binder preferably comprises the following raw materials in parts by weight: The above technical solution comprises 100 parts of smoked granular natural rubber, 50 parts of filler, 5 parts of zinc oxide, 2 parts of stearic acid, 0.8 parts of accelerator, and 2.5 parts of sulfur.

[0046] In this invention, the accelerator preferably includes accelerator CZ.

[0047] In this invention, the carbon black preferably includes one or more of N330, N220, N550 and N110.

[0048] The present invention does not impose any special limitation on the preparation method of the rubber composite material; any method known to those skilled in the art can be used.

[0049] 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.

[0050] Example 1 (1) Take fresh natural rubber latex with a dry rubber content of 20wt% and a nitrogen content of 0.3%, and use formic acid to coagulate it to obtain rubber clumps. The mass ratio of natural rubber latex to formic acid is 100:0.8 based on the dry rubber mass. The rubber clumps are crushed and granulated into rubber wet granules with a particle size of 5mm by a crepe and rubber granulator, and the stacking thickness is controlled to be 10cm. (2) Place the wet rubber granules in a smokehouse, add wood chips to an electric burner for incomplete combustion (excess air coefficient is 0.9) to generate smoke, control the smoke temperature at 40℃, the smoke flow rate at 0.5m / s, and continuously smoke for 2 hours (total phenol content in smoke is 10wt%, carbonyl compound content is 5wt%) to obtain smoked wet rubber granules. (3) Place the smoked wet rubber granules in a hot air drying device and dry at 60°C for 24 hours to obtain smoked natural rubber granules.

[0051] Example 2 (1) Take fresh natural rubber latex with a dry rubber content of 30wt% and a nitrogen content of 0.38%, and coagulate it by a combination of microbial coagulation and formic acid coagulation to obtain rubber granules. The mass ratio of natural rubber latex to formic acid is 100:0.5 based on dry rubber mass, and the mass ratio of natural rubber latex to microorganisms is 100:0.3. The rubber granules are crushed and granulated into rubber wet granules with a particle size of 12mm by a crepe and rubber granulator, and the stacking thickness is controlled to be 20cm. (2) Place the wet rubber granules in a smokehouse, add the sawdust to the electric burner for incomplete combustion (excess air coefficient is 0.9) to generate smoke, control the smoke temperature at 60℃, the smoke flow rate at 1.2m / s, and continuously smoke for 5h (total phenol content in smoke is 10wt%, carbonyl compound content is 10wt%) to obtain smoked wet rubber granules. (3) Place the smoked wet rubber granules in a hot air drying device and dry at 80°C for 15 hours to obtain smoked natural rubber granules.

[0052] Example 3 (1) Take fresh natural rubber latex with a dry rubber content of 40wt% and a nitrogen content of 0.6%, and use microbial coagulation to obtain rubber clumps. The mass ratio of natural rubber latex to formic acid is 100:0.3 based on dry rubber mass. The rubber clumps are crushed and granulated into rubber wet granules with a particle size of 20mm by a crepe and rubber granulator, and the stacking thickness is controlled to be 30cm. (2) Place the wet rubber granules in a smokehouse, add wood chips to an electric burner for incomplete combustion (excess air coefficient is 0.9) to generate smoke, control the smoke temperature at 80℃, the smoke flow rate at 2m / s, and continuously smoke for 8h (total phenol content in smoke is 30wt%, carbonyl compound content is 15wt%) to obtain smoked wet rubber granules. (3) Place the smoked wet rubber granules in a hot air drying device and dry at 100℃ for 8 hours to obtain smoked natural rubber granules.

[0053] Example 4 (1) Take fresh natural rubber latex with a dry rubber content of 25wt% and a nitrogen content of 0.35%, and use enzyme coagulation to obtain rubber clumps. The mass ratio of natural rubber latex to enzyme is 100:0.8 based on dry rubber mass. The rubber clumps are crushed and granulated into rubber wet granules with a particle size of 8mm by a crepe and rubber granulator, and the stacking thickness is controlled to be 15cm. (2) Place the wet rubber granules in a smokehouse, add the sawdust to the electric burner for incomplete combustion (excess air coefficient is 0.9) to generate smoke, control the smoke temperature at 50℃, the smoke flow rate at 0.8m / s, and continuously smoke for 4h (total phenol content in the smoke is 15wt%, carbonyl compound content is 8wt%) to obtain smoked wet rubber granules. (3) Place the smoked wet rubber granules in a hot air drying device and dry at 70°C for 20 hours to obtain smoked natural rubber granules.

[0054] Example 5 (1) Take fresh natural rubber latex with a dry rubber content of 35wt% and a nitrogen content of 0.4%, and coagulate it with formic acid and enzyme to obtain rubber granules. The mass ratio of natural rubber latex to formic acid is 100:0.4 based on dry rubber mass, and the mass ratio of natural rubber latex to enzyme is 100:0.4. The rubber granules are crushed and granulated into rubber wet granules with a particle size of 16mm by a crepe and rubber granulator, and the stacking thickness is controlled to be 25cm. (2) Place the wet rubber granules in a smokehouse, add the sawdust to the electric burner for incomplete combustion (excess air coefficient is 0.9) to generate smoke, control the smoke temperature at 70℃, the smoke flow rate at 1.5m / s, and continuously smoke for 6 hours (total phenol content in the smoke is 25wt%, carbonyl compound content is 12wt%) to obtain smoked wet rubber granules. (3) Place the smoked wet rubber granules in a hot air drying device and dry at 90°C for 10 hours to obtain smoked natural rubber granules.

[0055] Example 6 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled at 30 cm.

[0056] Example 7 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled at 15 cm.

[0057] Example 8 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled to be 5 cm.

[0058] Example 9 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled at 50 cm.

[0059] Example 10 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled to be 100 cm.

[0060] Example 11 Same as Example 1, except that the wet rubber particles have a particle size of 2 mm and the stacking thickness is controlled to be 10 cm.

[0061] Example 12 Same as Example 1, except that the wet rubber particles have a particle size of 20 mm and the stacking thickness is controlled to be 10 cm.

[0062] Example 13 Same as Example 1, except that the wet rubber particles have a particle size of 50 mm and the stacking thickness is controlled to be 10 cm.

[0063] Comparative Example 1 (Untreated with smoke) (1) Take the fresh natural rubber latex from Example 1 and coagulate it with formic acid to obtain rubber clumps. The mass ratio of natural rubber latex to formic acid is 100:0.8 based on the dry rubber mass. The rubber clumps are crushed and granulated into rubber wet granules with a particle size of 5 mm by a crepe and rubber granulator, and the stacking thickness is controlled to be 10 cm. (2) Place the wet rubber granules in a hot air drying equipment and dry them at 80°C for 24 hours to obtain untreated natural rubber granules.

[0064] Comparative Example 2 (Traditional Smoked Adhesive Patch Process) (1) Same as (1) in Example 2, except that the rubber block is pressed into a rubber hanging sheet with a thickness of 8mm after being crepeed and then suspended in the smoking equipment; (2) Same as (2) in Example 2; (3) Same as (3) in Example 2, to obtain smoked granular natural rubber.

[0065] Comparative Example 3 Same as Example 1, except that the wet rubber particles have a particle size of 55 mm and the stacking thickness is controlled to be 10 cm.

[0066] Comparative Example 4 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled at 105 cm.

[0067] Comparative Example 5 Same as Example 1, except that the wet rubber particles have a particle size of 1 mm and the stacking thickness is controlled to be 10 cm.

[0068] Comparative Example 6 Same as Example 1, except that the wet rubber particles have a particle size of 5 mm and the stacking thickness is controlled to be 2 cm.

[0069] The rubbers obtained in the examples and comparative examples were mixed and vulcanized according to the same basic formula (100 parts by weight of natural rubber, 50 parts by weight of carbon black N330, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 0.8 parts by weight of accelerator CZ, and 2.5 parts by weight of sulfur), and the abrasion resistance of the rubber composites was determined. The results are shown in Table 1.

[0070] Performance testing: Long-chain branching degree test: The long-chain branching degree of raw rubber was determined using a rubber processing analyzer. For details, please refer to (Industrial Crops and Products, 2026, 239, 122483).

[0071] Molecular weight distribution index: determined by gel permeation chromatography, and is the ratio of weight-average molecular weight to number-average molecular weight.

[0072] Abrasion resistance: The abrasion resistance was determined using the Akron abrasion tester in accordance with GB / T 1689-2014 standard.

[0073] Table 1 Performance test results of the rubber composite materials prepared in the examples and comparative examples

[0074] As can be seen from the table above: 1) Compared with Comparative Example 1, which was not smoked, the smoked natural rubber granules prepared in this embodiment of the invention showed a significant reduction in long-chain branching and a marked broadening of molecular weight distribution. This indicates that the smoked treatment effectively altered the molecular chain structure of the rubber.

[0075] 2) Compared with Comparative Example 3, the smoked granulated natural rubber prepared in Example 1 of this invention exhibits a significantly reduced degree of long-chain branching and a markedly broadened molecular weight distribution. This indicates that granulation with a particle size greater than 50 mm has a lower effect on reducing the degree of long-chain branching and results in a narrower molecular weight distribution.

[0076] 3) Compared with Comparative Example 4, the smoked granular natural rubber prepared in Example 1 of this invention exhibits a significantly reduced degree of long-chain branching and a markedly broadened molecular weight distribution. This indicates that the effect of reducing long-chain branching is less pronounced and the molecular weight distribution is narrower when the packing thickness is greater than 100 cm.

[0077] 4) Regarding abrasion resistance, the Akron abrasion values ​​of the embodiments of the present invention are all much lower than those of Comparative Example 1, and significantly better than those of Comparative Example 2 using the traditional sheet-like smoking process, as well as Comparative Examples 3 and 4. This directly proves that the rubber prepared by the method of the present invention has significantly improved comprehensive physical and mechanical properties, especially abrasion resistance.

[0078] In summary, the method for preparing smoked granulated natural rubber provided by this invention successfully integrates the advantages of smoked modification into an efficient granulated rubber production process, resulting in products with excellent performance, stable quality, and promising industrial application prospects.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 smoked granular natural rubber, characterized in that, Includes the following steps: After coagulating the natural rubber latex with a coagulant, the mixture is then creped and granulated in sequence to obtain wet rubber granules. The wet rubber granules have a particle size of 2-50 mm and a bulk thickness of 5-100 cm. The wet rubber granules are subjected to smoking treatment to obtain smoked wet rubber granules. The smoked wet rubber granules are dried to obtain the smoked natural rubber granules.

2. The preparation method according to claim 1, characterized in that, The particle size of the wet rubber granules is 5~30mm.

3. The preparation method according to claim 1 or 2, characterized in that, The thickness of the accumulated wet rubber granules is 10~50cm.

4. The preparation method according to claim 1, characterized in that, The smoking treatment is carried out at a temperature of 40~80℃ for 1~8 hours.

5. The preparation method according to claim 1 or 4, characterized in that, The fumigation treatment uses fumigation gas, which contains 10-30 wt% phenolic compounds and 5-15 wt% carbonyl compounds. The phenolic compounds include guaiacol, phenol, and 2,4-dimethylphenol, and the carbonyl compounds include acetaldehyde, acetone, and furfural compounds.

6. The preparation method according to claim 5, characterized in that, The smoke is produced by the incomplete combustion of wood chips or oil, wherein the excess air coefficient during incomplete combustion is <1.

0.

7. The preparation method according to claim 1 or 4, characterized in that, The flow rate of the smoke gas during the fumigation process is 0.5~2m / s.

8. The smoked granular natural rubber prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The smoked granular natural rubber has a long-chain branching degree of 1.4~2 and a molecular weight distribution index of 3.5~6.

0.

9. The application of the smoked granulated natural rubber according to claim 8 in the field of rubber products, characterized in that, The rubber products include engineering tires, aircraft tires, hoses, seals, medical latex products, or shoe soles.

10. A rubber composite material, characterized in that, The raw materials include the following parts by weight: The smoked granular natural rubber of claim 8 comprises 100 parts, 30-60 parts, filler, 4-6 parts, zinc oxide, 1-3 parts, stearic acid, 0.5-1 part, accelerator, and 2-3 parts, wherein the filler includes one or more of carbon black, silica, montmorillonite, calcium carbonate, and carbon nanotubes.

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