A rubber tire reinforcing filler and a method for making the same

Abstract

The present application belongs to the field of rubber tire manufacturing, and particularly relates to a rubber tire reinforcing filler and a preparation method thereof. The method comprises: 1) placing steel fiber powder in an aluminum-containing treatment solution, performing surface treatment, adjusting the solution system to be alkaline, and then aging to obtain modified steel fiber; 2) preparing steel wire glue, uniformly spraying the steel wire glue on the surface of the modified steel fiber by using an electrostatic charge spraying method to obtain functionalized fiber; and 3) preparing composite glue, placing the functionalized fiber in the composite glue for negative pressure impregnation, and then filtering to perform rolling curing and pre-sulfurization, thereby obtaining the rubber tire reinforcing filler. The present application constructs a special microstructure by etching deposition, combines silane coupling agent functionalized steel wire glue and an organic functionalized composite glue layer, significantly improves the interfacial adhesion strength of the filler and the steel wire core gold and the like in the belt layer, realizes uniform dispersion and fixation of the steel fiber in the belt layer with a small amount, greatly reduces the specific gravity, and retains the puncture resistance and wear resistance and the like.

Description

Technical Field

[0001] This invention belongs to the field of rubber tire manufacturing, and specifically relates to a rubber tire reinforcing filler and its preparation method. Background Technology

[0002] Traditional tires mostly use fiber materials such as nylon, which can meet basic driving needs, but when faced with increasingly complex road conditions and the requirements of high-performance vehicles, they have gradually revealed shortcomings such as insufficient strength and poor durability. Against this background, steel-belted tires emerged, which use steel cords as the skeleton material and achieve a major leap in performance.

[0003] Steel-belted tires offer significant performance advantages. Their strength far surpasses that of ordinary tires, effectively resisting road impacts and heavy loads when carrying heavy vehicles such as large trucks and construction vehicles, reducing the likelihood of deformation and damage, and ensuring transportation efficiency and driving safety. Simultaneously, steel-belted tires exhibit excellent durability, withstanding prolonged high-intensity operation, extending tire replacement cycles and reducing maintenance costs, which is particularly important for long-haul transport vehicles. In terms of handling stability, steel-belted tires, with their excellent resistance to deformation, enable vehicles to maintain precise steering response and stable driving posture during high-speed driving, emergency braking, and sharp cornering, enhancing the driving experience and safety.

[0004] Due to the unique structure of steel-belted tires, they feature special steel belt layers, typically in multiple layers. Different numbers of layers are suitable for different vehicle types and usage scenarios. For example, two-layer belted tires are commonly used as highway tires, while three- or four-layer belted steel-belted tires are usually used for special transport vehicles. However, their high strength and durability far exceed actual needs, leading to wasted vehicle performance resources and increased manufacturing costs. Furthermore, steel-belted tires have a higher specific gravity and density, increasing their weight. For vehicles with strict lightweight requirements, such as new energy vehicles, this increases power consumption, reduces driving range, and affects overall vehicle performance. It also increases fuel consumption and carbon emissions during transportation, and there is a certain degree of performance overkill. For special vehicles, the high weight limits the use of more belt layers to further enhance tire performance. Therefore, a key research direction for steel-belted tires at present is how to maintain performance while achieving lightweight design. The synergistic effect of fillers and steel core metal (i.e., the steel wires that make up the steel cord) to construct a new type of belt layer is an important research and development direction. However, common fillers have low compatibility with steel core metal, and may even have problems such as segregation, resulting in performance that is far below expectations. Therefore, the research on fillers has always been an important topic in the lightweighting of steel cord tires. Summary of the Invention

[0005] To address the problems of excessive density in existing steel-belt tire belt layers, which leads to overperformance in some scenarios but also affects overall vehicle performance due to excessive density, and also limits the application of more belt layers in some special scenarios, this invention provides a rubber tire reinforcing filler and a method for preparing the filler.

[0006] The main objective of this invention is to: 1. Construct a special filler suitable for steel wire tire belt layers.

[0007] 2. The filler has good compatibility with the rubber coating material of the steel wire tire belt layer and the steel wire core.

[0008] Third, the use of filler can significantly reduce the specific gravity of the steel wire tire belt layer while effectively maintaining most of the belt layer's properties.

[0009] To achieve the above objectives, the present invention adopts the following technical solution.

[0010] A method for preparing a rubber tire reinforcing filler, the method comprising: 1) placing steel fiber powder in an aluminum-containing treatment solution, performing surface treatment, adjusting the solution system to alkaline, and aging to obtain modified steel fiber.

[0011] 2) Prepare steel wire adhesive and use electrostatic spraying method to evenly spray the steel wire adhesive onto the surface of modified steel fiber to obtain functionalized fiber.

[0012] 3) Prepare the composite rubber, place the functionalized fibers in the composite rubber for negative pressure impregnation, and then filter for rolling curing and pre-vulcanization to obtain the rubber tire reinforcing filler.

[0013] Preferably, the steel fiber powder in step 1) is short fiber powder with a diameter of 0.300-0.400 mm; the aluminum-containing treatment solution in step 1) is a mixed iron-aluminum acid solution, which is prepared by the following method: First, industrial hydrochloric acid and industrial hydrofluoric acid are mixed with water to prepare an acidic base solution. The concentration of industrial hydrochloric acid in the acidic base solution is 110-130 mL / L and the concentration of industrial hydrofluoric acid is 10-20 mL / L. Then, ferric chloride is added at a ratio of 3.0-4.0 mol / L of acidic base solution and aluminum chloride is added at a ratio of 0.3-0.8 mol / L of acidic base solution. The mixture is stirred and mixed evenly to obtain the mixed iron-aluminum acid solution.

[0014] Preferably, the surface treatment in step 1) involves placing steel fiber powder in an aluminum-containing treatment solution and stirring at a constant temperature of 55-65°C for 10-15 minutes; the adjustment of the solution system to alkalinity in step 1) involves introducing ammonia gas into the solution system until the pH value is ≥12, then allowing it to stand for 25-35 minutes before filtering and drying to obtain modified steel fibers.

[0015] Preferably, the steel wire adhesive component in step 2) consists of 33-35 wt% carbon black N330, 3-5 wt% silane coupling agent KH-550, 1-2 wt% sulfur, and the balance being natural rubber. After dispensing according to the above components, the mixture is stirred for 15-20 minutes at an ambient temperature of 100-110°C and a rotation speed of 40-60 rpm, and then crushed to a mesh size of ≥800 to obtain the steel wire adhesive.

[0016] Preferably, the control parameters for the electrostatic spraying method in step 2) are: voltage 50-80kV, spraying distance 20-30cm, adhesive layer thickness 80-120μm, and after spraying, the functionalized fiber is obtained by keeping it in an environment with a temperature of 90-110℃ for 5-8 minutes.

[0017] Preferably, the composite adhesive in step 3) is prepared by the following method: natural rubber latex, peracetic acid, carbon black N550 and nano-silica are mixed evenly in a mass ratio of 5:(1.4~1.6):2.5:(0.3~0.5), and stirred for 1~2 hours under an environment with a temperature of 30~40℃ and a pressure of 0.5~1.0MPa to obtain the composite adhesive.

[0018] Preferably, the negative pressure impregnation process in step 3) controls the ambient pressure to be ≤0.1 atm; the rolling curing process in step 3) involves placing the material at 70-80℃ and continuously stirring and rolling it at a speed of 30-90 rpm for 25-35 minutes; the pre-vulcanization process in step 3) controls the temperature to be 120-130℃, the pressure to be 0.5-0.8 MPa, and the vulcanization time to be 10-15 minutes.

[0019] A rubber tire reinforcing filler.

[0020] Preferably, the rubber tire reinforcing filler is used for filling the steel wire tire belt layer.

[0021] Preferably, when the rubber tire reinforcing filler is used to fill the steel cord belt layer, it is added to the rubber coating and mixed evenly; the amount of rubber tire reinforcing filler added is 15-25 wt% of the rubber coating, while reducing the steel cord density by 30-50%.

[0022] The core of the technical solution of this invention lies in the significant improvement of the adhesive performance of rubber tire reinforcing filler through interface microstructure design, chemical bonding strengthening and organic-inorganic synergistic effect, and the successful preparation of high-performance rubber tire reinforcing filler.

[0023] First, the pretreatment of the steel wire microstructure is addressed. This invention utilizes a special aluminum-containing oxide etching solution to etch the surface of the steel fiber, creating micro- and nano-scale grooves and pores. This unique microstructure design leverages both mechanical anchoring and capillary wetting effects to significantly increase adhesive adhesion. Specifically, the roughened surface formed by extrusion provides numerous stable physical anchoring points for the adhesive. These surface grooves and pores interact to form a unique "locking structure." Under dynamic load conditions, this "locking structure" creates a strong mechanical interlock between the adhesive layer and the steel wire, effectively suppressing interfacial slippage and significantly reducing the risk of peeling. Simultaneously, the capillary force generated by the microporous structure plays a crucial role, driving the adhesive to penetrate rapidly and deeply into the pores, resulting in a significantly increased wetting depth compared to traditional smooth surfaces. This microstructure design not only lays a solid physical foundation for subsequent chemical bonding and synergistic effects but also directly enhances the adhesive properties of the rubber tire reinforcing filler.

[0024] Then, by adjusting the pH value, aluminum oxide compounds such as iron aluminate and iron oxide compounds are further deposited on the etched rough steel fiber surface, which provides a good foundation for subsequent coupling condensation and chemical bridging.

[0025] The modified steel fibers, after processing, first construct a three-level chemical bonding system of "steel fiber-adhesive layer-rubber" under the multi-level action of steel wire adhesive, which is the core measure of this invention to improve interfacial strength. This system is closely linked to the preceding microstructure design, further consolidating and strengthening the performance of the rubber tire reinforcing filler. Among them, KH-550, as a key coupling agent, undergoes a condensation reaction between its silanol groups (-Si-OH) and oxides (such as Fe-O, Al-O, etc.) and aluminate compounds (M-Al-O) on the surface of the steel wire to generate stable MO-Si bonds, achieving preliminary chemical bridging between the "steel fiber-adhesive layer". At the same time, the amino group (-NH2) at the end of the coupling agent also has the ability to form hydrogen bonds with the carboxyl groups (-COOH) in the rubber, further strengthening this connection. More importantly, the filler of this invention also undergoes pre-vulcanization treatment, during which preliminary cross-linking bonds are formed between the rubber molecular chains. In the subsequent use process, the calendering and rubber coating process during the processing of the belt layer will complete the entire vulcanization process, forming CSSC cross-linking bonds. This crosslinking reaction further solidifies the interfacial bonds bridged by the coupling agent into a complete and stable overall network structure. This chemical bonding system not only relies on the physical adhesion basis provided by the aforementioned microstructure design, but also tightly binds the various parts together through chemical reactions. This allows the rubber tire reinforcing filler to maintain high stability and reliability under various complex working conditions, achieving a significant improvement in interfacial strength. At the same time, it enables the filler of this invention to be effectively dispersed and stabilized in the banding layer.

[0026] Furthermore, the synergistic effect of modified natural rubber and nanofillers achieves stress dispersion and energy dissipation under dynamic loads. The epoxy groups of epoxidized natural rubber coordinate with the steel wire core metal interface, while nano-silica effectively disperses stress through a "particle-rubber" sliding mechanism, significantly reducing dynamic modulus differences. The abundant silanol groups (-Si-OH) on the surface of nano-silica are connected to the rubber molecular chains through weak hydrogen bonds. Under dynamic loads, the nanoparticles can undergo reversible sliding, converting local stress into heat energy, thereby effectively inhibiting crack propagation. This organic-inorganic synergistic effect not only leverages the stable structure provided by the aforementioned microstructure design and chemical bonding but also plays a unique role in dynamic environments, further enhancing the comprehensive performance of rubber tire reinforcing fillers.

[0027] Through the above treatment, the filler of the present invention can be effectively integrated into the belt layer, forming a cross-linked network with the adhesive material for interpenetration, fixation and connection. At the same time, the filler is in direct contact with the steel wire core gold cord, and also has good compatibility to achieve connection and fit.

[0028] Finally, this invention actually combines the pre-vulcanization process with the calendering and coating of the rubber compound during the preparation of the belt layer to form a multi-stage vulcanization process. This multi-stage vulcanization process is a key element ensuring the successful implementation of the entire technical solution. The multi-stage vulcanization process is carried out in stages to prevent the rubber layer from flowing and causing microstructure filling failure, while ensuring that the interfacial chemical bonds can fully react. In the pre-vulcanization stage, the rubber layer initially cross-links to form a gel network. This network structure can effectively fix the rubber liquid within the microstructure pores, preventing the rubber liquid from overflowing during the high-temperature final vulcanization, thereby ensuring the integrity and stability of the microstructure and providing a guarantee for the previously designed microstructure to function. In the final vulcanization stage, the high-temperature and high-pressure environment accelerates the sulfur cross-linking reaction, not only promoting the full formation of Fe-O-Si bonds and further strengthening the chemical bonding system, but also contributing to the perfection of the rubber cross-linking network and ensuring the integrity of the interfacial bonding. Through this multi-stage vulcanization process, the innovative points of the preceding microstructure design, chemical bonding strengthening, and organic-inorganic synergistic effect are organically combined, ultimately achieving a comprehensive improvement in the adhesive performance of the rubber tire reinforcement filler.

[0029] The advantages of this invention are as follows: This invention constructs a special microstructure through etching deposition, combined with silane coupling agent-functionalized steel wire adhesive and organic functionalized composite adhesive layer, which significantly improves the interfacial adhesion strength between the filler and the steel wire core, adhesive and other components in the belt layer. It achieves uniform dispersion and fixation of steel fibers in the belt layer with a smaller amount of material. Compared with conventional belt layers, steel fibers can replace a large amount of steel wire core in steel cord, greatly reducing the specific gravity while retaining a high degree of performance in terms of puncture resistance, abrasion resistance and other aspects. Detailed Implementation

[0030] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0031] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0032] Unless otherwise specified, the industrial hydrochloric acid used in the embodiments of the present invention is commercially available industrial hydrochloric acid with a standard concentration of 38 wt%, and the industrial hydrofluoric acid used in the embodiments of the present invention is commercially available industrial hydrofluoric acid with a standard concentration of 48 wt%.

[0033] Example 1: A method for preparing a rubber tire reinforcing filler, the method comprising: 1) mixing industrial hydrochloric acid and industrial hydrofluoric acid with water to prepare an acidic base solution, wherein the concentration of industrial hydrochloric acid in the acidic base solution is 110 mL / L and the concentration of industrial hydrofluoric acid is 10 mL / L, then adding ferric chloride at a ratio of 3.0 mol / L acidic base solution and adding aluminum chloride at a ratio of 0.3 mol / L acidic base solution, and stirring to mix evenly to obtain an iron-aluminum mixed acid solution.

[0034] 2) Take 0.300mm short steel fiber powder and place it in an aluminum-containing treatment solution. Stir for 15 minutes in a constant temperature environment of 55℃. After surface treatment, introduce ammonia gas into the solution system until the pH value is 12. Then let it stand for 35 minutes, filter and dry to obtain modified steel fiber.

[0035] 3) 33wt% carbon black N330, 3wt% silane coupling agent KH-550, 1wt% sulfur, and the balance is natural rubber. After mixing the above components, stir for 20 minutes at an environment of 100℃ and 40rpm. Then crush it to a mesh size of 800 to obtain steel wire rubber.

[0036] 4) The steel wire adhesive was uniformly sprayed onto the surface of the modified steel fiber using electrostatic spraying. The electrostatic spraying voltage was 50kV, the spraying distance was 20cm, and the adhesive layer thickness was 80μm. After spraying, the fiber was kept at 90℃ for 8 minutes to obtain the functionalized fiber.

[0037] 5) Mix natural rubber latex, peracetic acid, carbon black N550 and nano-silica in a mass ratio of 5:1.4:2.5:0.3 until homogeneous. Stir and mix for 2 hours at a temperature of 30℃ and a pressure of 0.5MPa to obtain the composite adhesive.

[0038] 6) The functionalized fibers are placed in the composite rubber and impregnated under negative pressure at an ambient pressure of 0.1 atm. After filtration, the material is placed at 70°C and continuously stirred and rolled at a speed of 30 rpm for 35 minutes. It is then vulcanized at a temperature of 120°C and a pressure of 0.5 MPa for 15 minutes to obtain the rubber tire reinforcing filler.

[0039] 7) Mix natural rubber, carbon black, zinc oxide, stearic acid, antioxidant 4020, accelerator NS and sulfur in a mass ratio of 100:60:5;2;2:1.5:2 to obtain a rubber coating material.

[0040] 8) Pass the steel cord of the steel cord belt through a twin-roll calender, add rubber tire reinforcing filler at an environment temperature of 90℃, and cover the surface with 1.5mm rubber material. Vulcanize for 15 minutes at an environment temperature of 150℃ and a pressure of 20MPa to obtain the reinforced rubber tire.

[0041] In step 8) of the embodiment, a control group was set up, and only the steel cord density and the amount of rubber tire reinforcing filler added (the amount added is calculated based on the rubber coating material, that is, the amount of reinforcing filler used accounts for the mass percentage of the original rubber coating material, the same below) were modified. The specific modifications are as follows.

[0042] Table 1: Comparison of different steel wire cord densities and filler addition amounts in Example 1:

[0043] The above S1-1 is a blank group.

[0044] The rubber tires prepared according to the parameters in Table 1 above were subjected to performance testing, and the specific characterization results are as follows.

[0045] Axial (Y-axis) tensile strength test: Dumbbell-shaped specimens with a thickness of 2.0±0.2mm were cut along the direction of the steel cord. Using a pneumatic clamp on a universal testing machine with an initial clamping distance of 50mm, the maximum tensile force was recorded at a tensile rate of 500mm / min. The strength of the blank group S1-1 was specified as 100%.

[0046] Transverse (X-axis) tensile strength test: Dumbbell-shaped specimens with a thickness of 2.0±0.2mm were cut along the direction perpendicular to the steel cord. Using a universal testing machine with a pneumatic clamp of 50mm initial clamping distance, the maximum tensile force was recorded at a tensile rate of 500mm / min. The strength of the blank group S1-1 was specified as 100%.

[0047] Abrasion resistance testing: The test sample is a cylinder with a diameter of 16±0.2mm and a thickness of 6±0.5mm. The sample is weighed and rotated 40 times using a rotary drum abrasion tester under conditions of 10N pressure and an H-18 type grinding wheel with a Shore hardness of 90. Mass loss is observed, and the abrasion resistance retention rate is calculated based on the percentage of mass retained after wear. The strength of the blank group S1-1 is specified as 100%.

[0048] Puncture resistance test: The material from the example was cut into 100×100mm square films with a thickness of 2.0±0.1mm. A puncture testing machine with a 1.0mm diameter conical needle was used to puncture the sample at a puncture rate of 50mm / min, and the maximum force value during the puncture process was recorded. The strength of the blank group S1-1 was specified as 100%.

[0049] Specific gravity test: The material of the example was cut into 10×10×2mm squares, and the specific gravity was calculated using the water displacement method.

[0050] Table 2: Performance test results of Example 1:

[0051] Analysis of the characterization results in Table 2 shows that the introduction of rubber tire reinforcing filler has a significant impact on the mechanical anisotropy, interfacial microstructure and macroscopic performance of the tire composite system, achieving multi-dimensional optimization of the tire material system.

[0052] From the perspective of anisotropy in mechanical properties, experimental groups S1-2 to S1-5 exhibited a significant mechanical property reconstruction effect with increasing amounts of rubber tire reinforcing filler. The Y-axis (axial) tensile strength showed a decreasing trend, directly related to the reduction in steel cord density; while the X-axis (transverse) tensile strength exhibited a nonlinear change pattern of first increasing and then stabilizing. This anisotropic transformation phenomenon, analyzed from the constitutive relationship of materials mechanics, is attributed to the secondary reinforcing network structure formed by the rubber tire reinforcing filler within the rubber matrix. The reinforcing filler establishes a continuous stress transmission path in the transverse direction, filling the mechanical property "blind spots" between steel cords in traditional tire structures.

[0053] Durability evaluation showed that the wear resistance retention rate of each experimental group was higher than 93%, with S1-4 and S1-5 reaching over 95%, demonstrating excellent wear resistance characteristics. Analysis of the wear mechanism revealed that the microstructure of the wear surface of the filler-modified samples was more uniform, and the standard deviation of the wear trajectory width was reduced. This is directly related to the optimized energy dissipation mechanism resulting from the restrictive effect of the filler on the movement of rubber molecular chains. Of particular note is the effective maintenance of puncture resistance. The puncture resistance of the S1-5 sample decreased by only about 3% compared to S1-1. Moreover, the reinforcing filler altered the crack propagation path, causing more frequent crack deflection and bifurcation, lengthening the crack propagation path, and increasing energy dissipation. This "crack passivation" mechanism plays a crucial role in improving the tire's puncture resistance.

[0054] Lightweighting benefit analysis shows that the introduction of rubber tire reinforcing fillers effectively reduces tire weight while maintaining performance. As the filler content increases, the steel cord density decreases, and the tire specific gravity decreases from 2.13 g / cm³ in S1-1. 3 It gradually decreased to 1.97 g / cm³ for S1-5. 3 This results in a weight reduction of approximately 7.51%. The lightweight design not only reduces energy consumption during use but also lowers carbon emissions during tire production by reducing the amount of steel wire used, achieving a dual optimization of economic and environmental benefits.

[0055] Compared to the blank group S1-1, the experimental groups S1-2 to S1-5 achieved synergistic adjustments in multiple dimensions of performance, including lateral strength, puncture resistance, wear resistance, and lightweight, while maintaining axial strength that meets design requirements. In particular, the formulations S1-4 and S1-5 showed the best performance in terms of the balance of various performance indicators, with average cardiac function very close to that of the S1-1 experimental group and a significantly lower proportion, representing the best performance balance point achievable under current technological conditions.

[0056] Characterization of the filler-matrix interface interaction revealed a significant positive correlation between the adhesive absorption effect and the amount of filler added. As the filler addition amount increased, the adhesive absorption weight gain rate showed a gradient increase. This weight gain phenomenon is mainly due to the strong adsorption capacity of the microporous structure on the filler surface for the rubber precursor, forming an extended interface layer. The adhesive successfully penetrates into the depth of the micropores, forming an effective mechanical anchoring structure.

[0057] Adhesive absorption capacity is a key parameter for maintaining the mechanical properties of composite materials. Under similar filler addition levels, the S1-4 / S1-5 group with high adhesive absorption weight gain rate exhibits significantly better puncture resistance than the low adhesive absorption group S1-3, with an increase in puncture resistance of approximately 22-28%. This difference can be attributed to the three-dimensional network interface structure formed by the "deep penetration of adhesive into micropores," which provides a more efficient stress transmission path. From the perspective of material-structure-performance relationships, this lightweight strategy is essentially achieved by optimizing the mechanical transmission path. Traditional tires mainly rely on high-density steel cords to provide mechanical properties, while this invention achieves more efficient stress distribution by constructing a ternary synergistic system of "steel cord-filler-rubber," which allows for maintaining or even improving overall performance while reducing the amount of steel cords used.

[0058] This invention achieves a technological upgrade of the tire material system from a traditional single reinforcement structure to a "steel wire + filler" synergistic reinforcement structure through the innovative application of rubber tire reinforcement fillers. This improves the overall performance of tires while meeting the automotive industry's demands for lightweighting, safety, and environmental protection.

[0059] Example 2: A method for preparing a rubber tire reinforcing filler, the method comprising: 1) mixing industrial hydrochloric acid and industrial hydrofluoric acid with water to prepare an acidic base solution, wherein the concentration of industrial hydrochloric acid in the acidic base solution is 120 mL / L and the concentration of industrial hydrofluoric acid is 15 mL / L, then adding ferric chloride at a ratio of 3.5 mol / L acidic base solution and adding aluminum chloride at a ratio of 0.55 mol / L acidic base solution, and stirring to mix evenly to obtain an iron-aluminum mixed acid solution.

[0060] 2) Take 0.350mm short steel fiber powder and place it in an aluminum-containing treatment solution. Stir for 13 minutes in a constant temperature environment of 60℃. After surface treatment, introduce ammonia gas into the solution system until the pH value is 13. Then let it stand for 30 minutes, filter and dry to obtain modified steel fiber.

[0061] 3) 34wt% carbon black N330, 4wt% silane coupling agent KH-550, 1.5wt% sulfur, and the balance is natural rubber. After mixing the above components, stir for 18 minutes at an ambient temperature of 105℃ and a rotation speed of 50rpm. Then crush it to a mesh size of 900 to obtain steel wire rubber.

[0062] 4) The steel wire adhesive was uniformly sprayed onto the surface of the modified steel fiber using electrostatic spraying. The electrostatic spraying voltage was 65kV, the spraying distance was 25cm, and the adhesive layer thickness was 100μm. After spraying, the fiber was kept at 100℃ for 7 minutes to obtain the functionalized fiber.

[0063] 5) Mix natural rubber latex, peracetic acid, carbon black N550 and nano silica in a mass ratio of 5:1.5:2.5:0.4 until homogeneous. Stir and mix for 1.5 h at a temperature of 35℃ and a pressure of 0.75MPa to obtain the composite adhesive.

[0064] 6) The functionalized fibers are placed in the composite rubber and impregnated under negative pressure at an ambient pressure of 0.08 atm. After filtration, the material is placed at 75°C and continuously stirred and rolled at a speed of 60 rpm for 30 minutes. It is then vulcanized at a temperature of 125°C and a pressure of 0.65 MPa for 13 minutes to obtain the rubber tire reinforcing filler.

[0065] 7) Mix natural rubber, carbon black, zinc oxide, stearic acid, antioxidant 4020, accelerator NS and sulfur in a mass ratio of 100:60:5;2;2:1.5:2 to obtain a rubber coating material.

[0066] 8) The steel cord of the steel cord belt is passed through a twin-roll calender, and rubber tire reinforcing filler is added under an environment of 95°C and the surface is covered with 1.5mm rubber material. It is vulcanized for 13 minutes under an environment of 155°C and 23MPa to obtain a reinforced rubber tire. The amount of rubber tire reinforcing filler added is 22wt% of the rubber material.

[0067] In step 8) of the embodiment, a control group was set up, and only the density of the steel wire cord was modified. The specific modifications are as follows.

[0068] Table 3: Comparison of different steel wire cord densities in Example 2:

[0069] The rubber tires prepared according to the parameters in Table 3 above were subjected to performance testing, and the specific characterization results are as follows.

[0070] Axial (Y-axis) tensile strength test: Dumbbell-shaped specimens with a thickness of 2.0±0.2mm were cut along the direction of the steel cord. Using a pneumatic clamp on a universal testing machine with an initial clamping distance of 50mm, the maximum tensile force was recorded at a tensile rate of 500mm / min. The strength of the blank group S1-1 was specified as 100%.

[0071] Transverse (X-axis) tensile strength test: Dumbbell-shaped specimens with a thickness of 2.0±0.2mm were cut along the direction perpendicular to the steel cord. Using a universal testing machine with a pneumatic clamp of 50mm initial clamping distance, the maximum tensile force was recorded at a tensile rate of 500mm / min. The strength of the blank group S1-1 was specified as 100%.

[0072] Abrasion resistance testing: The test sample is a cylinder with a diameter of 16±0.2mm and a thickness of 6±0.5mm. The sample is weighed and rotated 40 times using a rotary drum abrasion tester under the conditions of a 10N pressure and an H-18 type grinding wheel with a Shore hardness of 90. The mass loss is observed, and the abrasion resistance retention rate is calculated. The strength of the blank group S1-1 is specified as 100%.

[0073] Puncture resistance test: The material from the example was cut into 100×100mm square films with a thickness of 2.0±0.1mm. A puncture testing machine with a 1.0mm diameter conical needle was used to puncture the sample at a puncture rate of 50mm / min. The maximum force value during the puncture process was recorded, and the average value was calculated from 5 points. The strength of the blank group S1-1 was specified as 100%.

[0074] Specific gravity test: The material of the example was cut into 10×10×2mm squares, and the specific gravity was calculated using the water displacement method.

[0075] Table 4: Performance test results of Example 2:

[0076] Analyzing the characterization results in Table 4 above, compared to Example 1, Example 2 further optimized the performance of the rubber tire reinforcing filler by adjusting the parameters and raw material ratios in the preparation process. Specifically, increasing the concentrations of industrial hydrochloric acid and industrial hydrofluoric acid, and increasing the amounts of ferric chloride and aluminum chloride, allowed for a more complete reaction of the iron-aluminum mixed acid solution, thereby improving the performance of the modified steel fibers. Simultaneously, optimizing the steel wire adhesive formulation and increasing the amounts of carbon black N330 and silane coupling agent KH-550 improved the adhesion and abrasion resistance of the steel wire adhesive. Furthermore, increasing the voltage and spraying distance of electrostatic spraying and increasing the adhesive layer thickness made the preparation of functionalized fibers more reliable.

[0077] During the preparation of the composite rubber, the proportions and reaction conditions of each component were adjusted to achieve a more uniform mixing effect and higher reaction efficiency. The conditions for negative pressure impregnation and vulcanization were also optimized to ensure that the rubber tire reinforcing filler could fully penetrate into the functional fibers and form a good interfacial bond.

[0078] Based on the performance test results, the rubber tire prepared in Example 2 showed a slight decrease in Y-axis tensile strength, but improvements in X-axis tensile strength, abrasion resistance, and puncture resistance. In particular, the puncture resistance showed a more significant improvement compared to Example 1.

[0079] Example 3: A method for preparing a rubber tire reinforcing filler, the method comprising: 1) mixing industrial hydrochloric acid and industrial hydrofluoric acid with water to prepare an acidic base solution, wherein the concentration of industrial hydrochloric acid in the acidic base solution is 130 mL / L and the concentration of industrial hydrofluoric acid is 20 mL / L, then adding ferric chloride at a ratio of 4.0 mol / L acidic base solution and adding aluminum chloride at a ratio of 0.8 mol / L acidic base solution, and stirring to mix evenly to obtain an iron-aluminum mixed acid solution.

[0080] 2) Take 0.400mm short steel fiber powder and place it in an aluminum-containing treatment solution. Stir for 10 minutes in a constant temperature environment of 65℃. After surface treatment, introduce ammonia gas into the solution system until the pH value is 14. Then let it stand for 25 minutes, filter and dry to obtain modified steel fiber.

[0081] 3) 35wt% carbon black N330, 5wt% silane coupling agent KH-550, 2wt% sulfur, and the balance is natural rubber. After mixing the above components, stir for 15 minutes at an environment of 110℃ and 60rpm. Then crush it to a mesh size of 1000 to obtain steel wire rubber.

[0082] 4) The steel wire adhesive was uniformly sprayed onto the surface of the modified steel fiber using electrostatic spraying. The electrostatic spraying voltage was 80kV, the spraying distance was 30cm, and the adhesive layer thickness was 120μm. After spraying, the fiber was kept at 110℃ for 5 minutes to obtain the functionalized fiber.

[0083] 5) Mix natural rubber latex, peracetic acid, carbon black N550 and nano-silica in a mass ratio of 5:1.6:2.5:0.5 until homogeneous. Stir and mix for 1 hour at a temperature of 40℃ and a pressure of 1.0MPa to obtain the composite adhesive.

[0084] 6) The functionalized fibers are placed in the composite rubber and impregnated under negative pressure at an ambient pressure of 0.05 atm. After filtration, the material is placed at 80°C and continuously stirred and rolled at a speed of 90 rpm for 25 minutes. It is then vulcanized at a temperature of 130°C and a pressure of 0.8 MPa for 10 minutes to obtain the rubber tire reinforcing filler.

[0085] 7) Mix natural rubber, carbon black, zinc oxide, stearic acid, antioxidant 4020, accelerator NS and sulfur in a mass ratio of 100:60:5;2;2:1.5:2 to obtain a rubber coating material.

[0086] 8) The steel cord of the steel cord belt is passed through a twin-roll calender and coated with 1.5mm rubber material at an environment temperature of 100℃. It is then vulcanized for 10 minutes at an environment temperature of 160℃ and a pressure of 25MPa to obtain a reinforced rubber tire. The amount of reinforcing filler added to the rubber tire is 25wt% of the rubber material.

[0087] In step 8) of the embodiment, a control group was set up, and only the density of the steel wire cord was modified. The specific modifications are as follows.

[0088] Table 5: Comparison of different steel wire cord densities in Example 3:

[0089] The performance of the rubber tires prepared in the examples was tested, and the specific characterization results are as follows.

[0090] Axial (Y-axis) tensile strength test: Dumbbell-shaped specimens with a thickness of 2.0±0.2mm were cut along the direction of the steel cord. Using a pneumatic clamp on a universal testing machine with an initial clamping distance of 50mm, the maximum tensile force was recorded at a tensile rate of 500mm / min. The strength of the blank group S1-1 was specified as 100%.

[0091] Transverse (X-axis) tensile strength test: Dumbbell-shaped specimens with a thickness of 2.0±0.2mm were cut along the direction perpendicular to the steel cord. Using a universal testing machine with a pneumatic clamp of 50mm initial clamping distance, the maximum tensile force was recorded at a tensile rate of 500mm / min. The strength of the blank group S1-1 was specified as 100%.

[0092] Puncture resistance test: The material from the example was cut into 100×100mm square films with a thickness of 2.0±0.1mm. A puncture testing machine with a 1.0mm diameter conical needle was used to puncture the sample at a puncture rate of 50mm / min. The maximum force value during the puncture process was recorded, and the average value was calculated from 5 points. The strength of the blank group S1-1 was specified as 100%.

[0093] Table 6: Performance testing and characterization results of Example 3:

[0094] Analyzing the characterization results in Table 6 above, Example 3 further improves the preparation process of the rubber tire reinforcing filler compared to Example 2. By increasing the concentrations of industrial hydrochloric acid and industrial hydrofluoric acid, and increasing the amounts of ferric chloride and aluminum chloride, the reaction of the iron-aluminum mixed acid solution becomes more vigorous, generating more active iron-aluminum compounds, thereby further improving the performance of the modified steel fibers. Simultaneously, the formulation of the steel wire adhesive is also optimized, increasing the proportion of carbon black N330 and silane coupling agent KH-550. This not only improves the adhesion of the steel wire adhesive but also significantly enhances its wear resistance and anti-aging properties.

[0095] Based on the performance test results, the rubber tire prepared in Example 3 showed a slight decrease in Y-axis tensile strength, but an improvement in X-axis tensile strength and puncture resistance. Particularly in terms of puncture resistance, the rubber tire of Example 3 exhibited superior performance compared to Example 2, almost completely equivalent to the puncture resistance of the high-density steel cord in the control group.

[0096] Comparative Example 1: Based on Example 2, this example only modifies the fiber filler; the remaining steps are the same as in Example 2. Specific settings are as follows.

[0097] Table 7: Comparison Table of Process Adjustments for Comparative Example 1

[0098] The performance testing method for the product of Comparative Example 1 is completely consistent with that of Example 1, and the characterization results are shown in the table below.

[0099] Table 8: Comparison of performance test characterization results between Comparative Example 1 and Example 2:

[0100] Analysis of the characterization results in Table 8 shows that replacing the steel fibers of this invention with nylon short fibers significantly degrades the performance of the composite system. From the perspective of material constitutive properties, the modulus of nylon short fibers is significantly lower than that of the steel fibers of this invention. This fundamental difference prevents nylon fibers from forming an effective load transfer path in the composite system. In sample D1-1, the modulus gradient between the fiber and the rubber matrix is ​​too large and the compatibility is poor, while in Example 2, the steel fibers with special surface treatment form a transition zone of about 5-8 μm wide, and the modulus shows a gradient distribution. During the deformation of the rubber matrix, the nylon fibers undergo significant bending and buckling due to insufficient stiffness, resulting in a significant reduction in stress transfer efficiency. This stiffness mismatch effect is directly reflected in the Y-axis tensile strength of D1-1, which is only 72% of that of the blank group, far lower than the 88% of Example 2, indicating that nylon short fibers cannot effectively cooperate with the steel cord to bear the axial load.

[0101] In D1-1, only physical adsorption characteristics were observed on the nylon fiber surface, failing to form a similar chemical bonding structure. Example 2 showed an elemental interdiffusion region approximately 2.5 μm wide at the fiber-rubber interface, while the transition region width at the D1-1 interface was less than 0.8 μm, indicating poor interfacial compatibility. The interfacial bond strength of D1-1 was only 43% of that of Example 2. This significant difference in interfacial bond strength is one of the fundamental reasons for the deterioration of the composite material's performance, indicating severe interfacial stress concentration and a significantly increased risk of interfacial failure.

[0102] The stress transfer efficiency of nylon short fibers in composite systems is far lower than that of steel fibers, leading to early failure characteristics. This is directly reflected in the X-axis tensile strength, where D1-1 only reaches 66% of the control group. This indicates that steel fibers provide significantly better transverse reinforcement to the rubber matrix than nylon fibers, and that nylon fibers, due to their low modulus and poor compatibility, are essentially unable to achieve X-axis reinforcement and may even cause severe deterioration. Furthermore, due to insufficient stiffness, nylon fibers cannot form an effective "bridging effect" in the composite system, resulting in a significant reduction in microcrack propagation resistance, which is consistent with the poor wear resistance test results of D1-1. The wear volume of D1-1 is significantly higher than that of Example 2, and the wear surface roughness increases by approximately 42%, indicating that nylon short fibers cannot effectively improve the wear resistance of the rubber matrix.

[0103] Specific gravity analysis showed that although the overall density of the composite material in D1-1 was slightly higher due to the use of lower-density nylon fibers (due to the good adhesive absorption capacity of nylon itself), it was close to that of Example 2, indicating that the filler of the present invention has excellent adhesive absorption capacity. In contrast, the D1-1 experimental group still produced a significant weight reduction effect, but this weight reduction benefit was offset or even covered by a significant decrease in performance. Based on the "performance / weight" index evaluation, the overall efficiency of D1-1 was only about 68% of that of Example 2, indicating that simply using low-density fibers cannot achieve true weight reduction optimization.

[0104] Comparative Example 2: Based on Example 2, this example only modifies the modified steel fiber filler; the remaining steps are the same as in Example 2. Specific settings are as follows.

[0105] Table 9: Comparison Table of Process Adjustments for Comparative Example 2

[0106] The performance testing method for the product of Comparative Example 2 is completely consistent with that of Example 1, and the characterization results are shown in the table below.

[0107] Table 10: Comparison of performance test characterization results between Comparative Example 2 and Example 2:

[0108] Analysis of the characterization results in Table 10 shows that the original steel fibers without surface modification lead to a significant deterioration in the performance of the composite system, fully demonstrating the decisive role of interfacial chemical bonding and microstructure engineering in the reinforcement of the filler-matrix interface.

[0109] From the perspective of surface chemical properties, in Example 2, a covalent chemical bond network is formed between the metal matrix, silicon-oxygen bridging bonds, and rubber molecular chains on the surface of the steel fiber after acid treatment and coupling agent spraying. In contrast, D2-1 lacks chemical bonding sites with rubber molecular chains, and interfacial chemical bonding is absent.

[0110] Microscopic morphology characterization revealed the significant impact of surface modification on the surface structure of steel fibers. The surface roughness parameter of the steel fibers in Example 2 reached 380 nm, while that of the original steel fibers in D2-1 was only 42 nm, a difference of nearly an order of magnitude. The acid-treated steel fiber surface formed micro-nano-scale pit structures with a depth of approximately 0.5–1.5 μm. These structures increased the effective specific surface area and formed mechanical anchoring points. In Example 2, the rubber molecular chains penetrated deeply into the pits on the fiber surface, forming a finger-like interlocking structure; while the interface of D2-1 showed a clear flat interface, lacking mechanical interlocking effect. This difference in microscopic morphology explains the insufficient amount of adhesive in D2-1 due to its smooth surface, directly limiting the interfacial contact area and adhesion strength. The significant difference in interfacial stress transfer efficiency is directly reflected in the macroscopic mechanical properties: the Y-axis tensile strength of D2-1 was only 68% of that of the blank group, significantly lower than the 88% of Example 2; the X-axis tensile strength decreased to 96%, without producing a strengthening effect, lower than Example 2. Of particular note is that in the puncture resistance test, the maximum puncture force that D2-1 could withstand decreased by about 18% compared with Example 2, and the puncture energy decreased by about 25%. This indicates that under complex stress conditions, the interfacial bonding strength plays a decisive role in the mechanical properties of the composite material.

[0111] These interfacial defects collectively lead to significant degradation in the axial strength, transverse strength, and puncture resistance of the composite material. This comparative experiment systematically verifies the crucial role of surface engineering in steel fiber reinforced rubber composites, particularly the synergistic effect between the microstructure modification resulting from acid treatment and the chemical bonding network established by coupling agent spraying, providing a scientific basis for the interfacial design of high-performance tire composite materials.

[0112] Comparative Example 3: Based on Example 2, this example only modifies the reinforced rubber tire; the remaining steps are the same as in Example 2. The specific settings are as follows.

[0113] Table 11: Comparison Table of Process Adjustments for Comparative Example 3

[0114] The performance testing method for the product of Comparative Example 3 was completely consistent with that of Example 1, and the characterization results are shown in the table below.

[0115] Table 12: Comparison of performance test characterization results between Comparative Example 3 and Example 2:

[0116] Analysis of the characterization results in Table 12 above shows that the traditional carbon black filling system and the reinforced filler system of the present invention exhibit fundamental differences in microstructure, mechanical reinforcement mechanism, anisotropic characteristics and lightweight benefits, fully verifying the significant advantages of innovative filler technology in tire composite material design.

[0117] Traditional carbon black N330 and the reinforcing filler of this invention differ significantly in geometry and size. Carbon black N330 exhibits a typical spherical aggregate structure with a primary particle size of approximately 28–36 nm, while the reinforcing filler of this invention has a fibrous structure with a high aspect ratio >100, a diameter of approximately 15–25 μm, and a length of 2–5 mm. This difference in geometry determines that the two fillers have drastically different reinforcing mechanisms in the composite system. In D3-1, the carbon black forms a network structure in the rubber matrix, with a typical three-dimensional random distribution; while in Example 2, the filler of this invention exhibits obvious orientation, forming an ordered and oriented reinforcing structure. This difference in microstructure directly results in D3-1 achieving only 75% of the Y-axis tensile strength, lower than the 88% of Example 2; more significantly, the X-axis tensile strength drops sharply to 88%, far lower than Example 2, fully exposing the fundamental limitations of traditional carbon black fillers in terms of transverse reinforcing ability.

[0118] In D3-1, the carbon black-rubber interface forms a confined rubber layer as the main reinforcement mechanism; while in Example 2, the macroscopic continuous reinforcement network established by the filler of this invention provides the reinforcement effect through stress transfer and load sharing mechanisms. The movement of rubber molecular chains in D3-1 is less restricted by carbon black, indicating that the latter significantly enhances the constraint ability on polymer chain segment activity. Under high strain conditions, the carbon black network structure is prone to collapse, while the filler network of this invention can still maintain effective load transfer.

[0119] The specific gravity of D3-1 reached 1.96, slightly lower than that of Example 2. This difference stems from the fundamental difference between the two design strategies and the difference in adhesive absorption capacity after filling. In reality, the carbon filler filling creates several gaps and pores, leading to a further decrease in specific gravity. D3-1 adopts the traditional reinforcement scheme of "increasing steel cord density + carbon black filling". Due to the increase in high-density steel wire content, the overall density inevitably increases. In contrast, Example 2, through the innovative design of "optimizing steel cord distribution + synergistic reinforcement of the filler of this invention", reduces the amount of steel wire used while compensating for or even surpassing the performance level of the traditional design through the lateral reinforcement effect of the filler of this invention.

[0120] Comparative Example 4: Based on Example 2, this example omits the pre-vulcanization step; the remaining steps are the same as in Example 2. Specific settings are as follows.

[0121] Table 13: Comparison Table of Process Adjustments for Comparative Example 4

[0122] The performance testing method for the product of Comparative Example 4 was completely consistent with that of Example 1. Partial performance characterization was performed, and the characterization results are shown in the table below.

[0123] Table 14: Comparison of performance test characterization results between Comparative Example 4 and Example 2:

[0124] Analysis of the characterization results in Table 14 shows that the lack of pre-curing process leads to a cascade effect of microstructural failure and macroscopic performance collapse in steel fiber reinforced rubber composites. At the molecular crosslinking network level, the absence of pre-curing prevents the D4-1 sample from forming a preliminary sulfur crosslinking structure. This stage is a critical temperature window for the formation of polysulfide bonds in CSSCs. These initial crosslinking points construct a semi-cured gel network, which is crucial for fixing the adhesive within the micropores. The lack of this pre-crosslinking structure results in abnormally high fluidity in the D4-1 sample during the final high-temperature curing stage, causing the adhesive within the micropores to melt and overflow before sufficient crosslinking, thus destroying the designed micro-anchoring structure. Regarding interfacial chemical bonding, the pre-curing temperature range is also the optimal temperature window for the hydrolysis-condensation reaction of the silane coupling agent KH-550. At this temperature, the ethoxy groups in the KH-550 molecule undergo moderate hydrolysis to generate active silanol groups (-Si-OH), which then condense with the hydroxyl groups on the Fe / Al oxide layer on the steel fiber surface to form a stable Fe-O-Si covalent bond network. D4-1 directly enters the high-temperature final vulcanization stage, causing partial thermal degradation of the coupling agent molecules before the reaction, preventing the formation of an effective interfacial chemical bond structure and losing the molecular link bridging the steel fiber and the rubber matrix. This microstructural defect directly leads to a systematic degradation of macroscopic mechanical properties. The Y / X axis tensile strength of D4-1 decreased by 14% / 19%, respectively. This mechanical property deterioration stems from a significant decrease in interfacial stress transfer efficiency. The puncture resistance of D4-1 decreased sharply by 25% compared to Example 2. Cross-sectional analysis shows that this is closely related to the crack propagation path—in D4-1 lacking effective interfacial bonding, cracks mainly propagate rapidly along the interfacial region; while in Example 2, the effective interfacial bonding makes the crack propagation path more tortuous, increasing energy absorption. Durability assessment also shows that the wear of D4-1 increased to 2.2 times that of Example 2, mainly due to the ease of peel wear between the adhesive layer and the fiber, resulting in a loss of the ability to synergistically resist wear.

[0125] This example verifies the dual crucial role of pre-vulcanization in steel fiber reinforced rubber composites. On one hand, the preliminary cross-linking network formed by pre-vulcanization effectively controls the flowability of the adhesive, preventing overflow during the high-temperature stage of final vulcanization and ensuring the integrity of the micro-anchoring structure. On the other hand, pre-vulcanization provides the optimal temperature window for interfacial coupling reactions, promoting the formation of Fe-O-Si chemical bond networks and strengthening interfacial bonding performance. The full-spectrum performance collapse of D4-1 provides reverse verification, confirming the irreplaceable role of the multi-stage vulcanization process (pre-vulcanization + final vulcanization) emphasized in this invention in achieving the three-in-one reinforcement mechanism of "microstructure design - chemical bonding - organic-inorganic synergy".

[0126] Comparative Example 5: Based on Example 2, this example only modifies the modified steel fiber process; the remaining steps are the same as in Example 2. The specific settings are as follows.

[0127] Table 15: Comparison Table of Process Adjustments for Comparative Example 5

[0128] The performance testing method for the product of Comparative Example 5 was completely consistent with that of Example 1. Partial performance characterization was performed, and the characterization results are shown in the table below.

[0129] Table 16: Comparison of performance test characterization results between Comparative Example 5 and Example 2:

[0130] Analysis of the characterization results in Table 16 above shows that surface microstructure characteristics have a decisive influence on the filler-rubber interfacial interaction and the overall performance of the composite material. Sample D5-1 was prepared using a non-etching process, maintaining a dense and smooth surface, lacking an effective microporous structure, leading to a significant deterioration in interfacial performance and mechanical properties. The adhesive absorption weight gain of D5-1 was only 0.2%, far lower than the 3.8% of Example 2 (a reduction of approximately 95%). This significant difference stems directly from the fundamental difference in microstructure. The etched surface of Example 2 formed a three-dimensional network-like microporous structure, increasing the specific surface area; while the surface of D5-1 remained relatively smooth, with only nanoscale roughness. This difference in microstructure results in a qualitative difference in the penetration ability of the rubber precursor during impregnation, quantitatively manifested as a significant difference in adhesive absorption weight gain. Interfacial bonding strength testing revealed the key influence of surface microporous structure on interfacial bonding performance. The interfacial peel strength of D5-1 was 67% lower than that of Example 2. Firstly, the lack of microporous structure led to the loss of mechanical anchoring effect, with interfacial bonding relying mainly on weaker physical adsorption forces. Secondly, interfacial bonding strength is directly proportional to the actual contact area, resulting in a significant reduction in the effective contact area. This difference in interfacial characteristics directly translates to macroscopic mechanical properties, particularly transverse tensile strength. The X-axis tensile strength of D5-1 was only 89%, significantly lower than the 112% of Example 2, indicating a significant deficiency in the filler-rubber matrix synergy. Notably, the specific gravity of D5-1 was slightly lower than that of Example 2, decreasing by approximately 3%. This density difference is directly attributed to the different amount of adhesive adsorbed—the microporous structure in Example 2 adsorbed more rubber, resulting in a slightly higher overall density. However, this slight weight advantage is far from sufficient to compensate for the significant performance decline, especially the 23% decrease in X-axis tensile strength. This trade-off clearly demonstrates that the "adhesive adsorption weight gain" caused by the microporous structure is a necessary cost in exchange for interfacial strengthening and performance improvement, representing a reasonable design trade-off.

[0131] This example verifies the core mechanism of this invention: "etching microporous structures can effectively improve adhesive absorption capacity and specific gravity, and effectively enhance interfacial bonding performance." The research results indicate that in the design of steel fiber reinforced rubber composites, surface microporous structures are key to constructing efficient interfaces, and the lightweight goal should primarily be achieved by optimizing the overall structural design and reducing the amount of steel cord used, rather than sacrificing the interfacial bonding ability of the filler.

Claims

1. A method for preparing a rubber tire reinforcing filler, characterized in that, The method includes: 1) placing steel fiber powder in an aluminum-containing treatment solution, performing surface treatment, adjusting the solution system to alkaline, and aging to obtain modified steel fibers; 2) preparing steel wire adhesive, and uniformly spraying the steel wire adhesive onto the surface of the modified steel fibers using an electrostatic spraying method to obtain functionalized fibers; 3) preparing composite adhesive, placing the functionalized fibers in the composite adhesive for negative pressure impregnation, followed by filtration for rolling curing and pre-vulcanization to obtain rubber tire reinforcing filler; Step 2) The steel wire adhesive consists of 33-35 wt% carbon black N330, 3-5 wt% silane coupling agent KH-550, 1-2 wt% sulfur, and the balance being natural rubber. After dispensing the above components, the mixture is stirred for 15-20 minutes at a temperature of 100-110 ℃ and a speed of 40-60 rpm. Then, it is crushed to a mesh size of ≥800 to obtain the steel wire adhesive. Step 3) The composite adhesive is prepared by the following method: natural rubber latex, peracetic acid, carbon black N550 and nano-silica are mixed evenly in a mass ratio of 5:(1.4~1.6):2.5:(0.3~0.5), and stirred for 1~2 h under an environment with a temperature of 30~40 ℃ and a pressure of 0.5~1.0 MPa to obtain the composite adhesive.

2. The method for preparing a rubber tire reinforcing filler according to claim 1, characterized in that, Step 1) The steel fiber powder is short fiber powder with a diameter of 0.300-0.400 mm; Step 1) The aluminum-containing treatment solution is a mixed iron-aluminum acid solution, which is prepared by the following method: First, industrial hydrochloric acid and industrial hydrofluoric acid are mixed with water to prepare an acidic base solution. The concentration of industrial hydrochloric acid in the acidic base solution is 110-130 mL / L and the concentration of industrial hydrofluoric acid is 10-20 mL / L. Then, ferric chloride is added according to the dosage ratio of 3.0-4.0 mol / L acidic base solution and aluminum chloride is added according to the dosage ratio of 0.3-0.8 mol / L acidic base solution. The mixture is stirred and mixed evenly to obtain the mixed iron-aluminum acid solution.

3. A method for preparing a rubber tire reinforcing filler according to claim 1 or 2, characterized in that, Step 1) The surface treatment involves placing steel fiber powder in an aluminum-containing treatment solution and stirring at a constant temperature of 55-65 ℃ for 10-15 min; Step 1) The adjustment of the solution system to alkalinity involves introducing ammonia gas into the solution system until the pH value is ≥12, then letting it stand for 25-35 min, filtering and drying to obtain modified steel fibers.

4. The method for preparing a rubber tire reinforcing filler according to claim 1, characterized in that, Step 2) The control parameters for the electrostatic spraying method are: voltage 50-80 kV, spraying distance 20-30 cm, adhesive layer thickness 80-120 μm, and after spraying, keep warm in an environment with a temperature of 90-110 ℃ for 5-8 min to obtain functionalized fibers.

5. The method for preparing a rubber tire reinforcing filler according to claim 1, characterized in that, Step 3) The negative pressure impregnation process controls the ambient pressure to ≤0.1 atm; Step 3) The rolling curing process involves placing the material at 70-80 ℃ and continuously stirring and rolling at 30-90 rpm for 25-35 min; Step 3) The pre-vulcanization process controls the temperature to 120-130 ℃, the pressure to 0.5-0.8 MPa, and the vulcanization time to 10-15 min.

6. A rubber tire reinforcing filler prepared by any one of claims 1 to 5.

7. The rubber tire reinforcing filler according to claim 6, characterized in that, The rubber tire reinforcing filler is used to fill the belt layer of the steel wire tire.

8. The rubber tire reinforcing filler according to claim 7, characterized in that, When the rubber tire reinforcing filler is used to fill the steel cord belt layer, it is added to the rubber coating and mixed evenly; the amount of rubber tire reinforcing filler added is 15-25 wt% of the rubber coating, while reducing the steel cord density by 30-50%.

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