Modification method of one-bath dipping modified aramid fiber and application of one-bath dipping modified aramid fiber in preparation of rubber composite material

Abstract

The invention discloses a modification method of one-bath dipping modified aramid fiber and application of the one-bath dipping modified aramid fiber to preparation of a rubber composite material, and aims to solve the problems that a traditional two-bath dipping modification process is complex, the reaction efficiency is low and an interface is not uniform. The one-bath dipping modified aramid fiber is prepared by mixing epoxy resin E51, glycidyl methacrylate (GMA), blocked hexamethylene diisocyanate (HDI) and butadiene-vinylpyridine rubber latex (VP latex) in a water phase to react to form one-bath dipping liquid, performing primary dipping treatment on aramid fiber, and drying at 80 DEG C for 10 minutes; the modified aramid fiber reinforced styrene-butadiene rubber composite material can be prepared from the modified aramid fiber, styrene-butadiene rubber, white carbon black and auxiliaries through banburying (110-140 DEG C, 6-8 minutes to realize an isocyanate deblocking reaction), open milling and vulcanization processes. Through the design of a multi-component synergistic one-bath system, the production process is simplified, chemical bonding and interface toughness regulation and control of the aramid fiber and the rubber matrix are realized, the mechanical property and stability of the composite material are remarkably improved, and the preparation method is suitable for industrial production of the rubber reinforced material.

Description

Technical Field

[0001] This invention relates to the field of high-performance fiber surface modification technology, specifically to a one-bath impregnation modification method for aramid fibers and its application in preparing rubber composites. It is particularly suitable for interface optimization in rubber matrix reinforcement materials, achieving efficient bonding between aramid fibers and styrene-butadiene rubber matrix through a one-bath process, thereby improving the overall performance of the composite material. Background Technology

[0002] Aramid fibers, with their ultra-high strength, high modulus, and excellent thermal stability, have become ideal reinforcing fillers in the field of high-performance rubber composites, and have broad application prospects in industrial products such as tires, seals, and transmission belts. However, the amide groups in the aramid fiber molecular chain are chemically inert and have low surface polarity, resulting in poor interfacial compatibility and weak adhesion between them and polymer matrices such as styrene-butadiene rubber. This makes them prone to interfacial delamination under stress, severely limiting their reinforcing effect.

[0003] To address the aforementioned issues, various surface modification methods for aramid fibers have been developed in the prior art. Among these, bilayer (two-bath) impregnation modification is a relatively common technical route, which constructs an adhesive layer and a crosslinking layer through two impregnation steps to achieve interfacial reinforcement. However, this type of method has certain drawbacks: on the one hand, the two-bath process is cumbersome, requiring the separate preparation of two impregnation solutions and two impregnation and drying treatments, resulting in low production efficiency and the possibility of uneven interfacial layer structure due to parameter deviations in the two treatments; on the other hand, the synergy of the two-step reaction is difficult to control precisely, which can easily lead to problems such as weak bonding between the modified layer and the fiber surface or insufficient crosslinking with the rubber matrix, affecting the performance stability of the composite material.

[0004] Furthermore, existing one-bath modification systems often suffer from poor component compatibility and low reaction efficiency: some systems use single-functional-group modifiers, failing to simultaneously achieve fiber surface activation and matrix crosslinking; while some multi-component systems are prone to premature polymerization or delamination due to mismatched reactivity of components, resulting in poor modification effects. Therefore, developing a simplified, component-synergistic, and stable one-bath impregnation modification method is of great significance for promoting the industrial application of aramid fibers in rubber reinforcement. Summary of the Invention

[0005] The purpose of this invention is to provide a one-bath impregnation modification method for aramid fibers and its application in the preparation of rubber composites. This invention overcomes the shortcomings of existing two-bath impregnation modification processes, such as complexity, low reaction efficiency, and non-uniform interface, as well as the problems of poor component compatibility and unsatisfactory modification effects in existing one-bath systems. By designing a multi-component synergistic one-bath impregnation system, this invention achieves efficient activation and interface functionalization of the aramid fiber surface, while simplifying the process flow and ensuring stable bonding between the modified layer and the fiber and rubber matrix, ultimately improving the mechanical properties and interface stability of styrene-butadiene rubber composites.

[0006] The technical solution of the present invention is as follows: a method for modifying aramid fibers by one-bath impregnation, wherein the modification method is to first mix epoxy resin E51, glycidyl methacrylate (GMA), blocked hexamethylene diisocyanate (HDI) and butadiene-pyridine latex (VP latex) in an aqueous phase to form a one-bath impregnation solution, add aramid fibers to the one-bath impregnation solution to modify the aramid fibers by one-bath impregnation, and then dry the fibers after impregnation to obtain one-bath impregnated modified aramid fibers.

[0007] The aforementioned one-bath impregnation modification method for aramid fibers is carried out according to the following steps: (1) Preparation of one-bath impregnation solution: Take 55-65g of deionized water, start magnetic stirring at 400-600rpm, add 2.5-3.5g of epoxy resin E51 and 1.5-4.5g of glycidyl methacrylate, and continue stirring for 10-20 minutes until evenly dispersed; then add 6.5-7.5g of blocked hexamethylene diisocyanate, and stir for 18-22 minutes to form a homogeneous system; finally, slowly add 18-22g of butadiene-pyridine latex, keep stirring at low speed for 8-12 minutes, let stand for 25-35 minutes to degas, and then add deionized water to a total mass of 100g to obtain one-bath impregnation solution; (2) Aramid fiber modification treatment: 3.5-4.5g of aramid fiber, which has been cleaned and dried with acetone, is immersed in the one-bath impregnation solution prepared in step (1) for 8-12 minutes at room temperature. After being taken out, it is placed in an oven at 75-85℃ for 8-12 minutes to remove surface moisture, thus completing the one-bath impregnation treatment and obtaining one-bath impregnated modified aramid fiber.

[0008] In step (1) above, the preparation of the one-bath impregnation solution is as follows: Take 60g of deionized water, start magnetic stirring at 500rpm, add 3g of epoxy resin E51 and 3g of glycidyl methacrylate, and continue stirring for 15 minutes until evenly dispersed; then add 7g of blocked hexamethylene diisocyanate, and stir for 20 minutes to form a homogeneous system; finally, slowly add 20g of butadiene-pyridine latex, keep stirring at low speed for 10 minutes, let stand for 30 minutes to degas, and then add deionized water to a total mass of 100g to obtain the one-bath impregnation solution.

[0009] In step (2) above, the aramid fiber is modified by immersing 4g of aramid fiber, which has been cleaned and dried with acetone, in 100g of one-bath impregnation solution prepared in step (1) for 10 minutes at room temperature. After taking it out, it is placed in an oven at 80℃ for 10 minutes to dry the surface moisture, thus completing the one-bath impregnation treatment and obtaining one-bath impregnated modified aramid fiber.

[0010] The aforementioned rubber composite material is prepared by one-bath impregnation of modified aramid fibers and styrene-butadiene rubber matrix through internal mixing, open milling, and vulcanization.

[0011] The aforementioned application of one-bath impregnation modified aramid fiber in the preparation of rubber composite materials, the raw materials of the rubber composite material, calculated by weight composition, consist of 180-220 parts of styrene-butadiene rubber, 3-5 parts of one-bath impregnation modified aramid fiber, 75-85 parts of silica, 28-32 parts of rubber compounding agent, and 3-4 parts of sulfur vulcanizing agent; the rubber compounding agent consists of 8-12 parts of zinc oxide, 6-10 parts of stearic acid, 4-5 parts of accelerator M, 0.8-1.2 parts of accelerator D, 3.5-4.5 parts of accelerator DM, 0.5-0.8 parts of accelerator TMTD, and 2.5-3.5 parts of antioxidant 4010.

[0012] Specifically, the raw materials of the aforementioned rubber composite material, calculated by weight, consist of 200 parts of styrene-butadiene rubber, 4 parts of one-bath impregnated modified aramid fiber, 80 parts of silica, 30.98 parts of rubber compounding agent, and 3.4 parts of sulfur vulcanizing agent; the rubber compounding agent consists of 10 parts of zinc oxide, 8 parts of stearic acid, 4.42 parts of accelerator M, 1 part of accelerator D, 3.92 parts of accelerator DM, 0.64 parts of accelerator TMTD, and 3 parts of antioxidant 4010.

[0013] The aforementioned method for preparing the rubber composite material involves impregnating 3-5 parts of modified aramid fiber, 180-220g of styrene-butadiene rubber matrix, and 75-85g of silica in a one-bath mixing process at 110-140℃ for 6-8 minutes, cooling to 60-80℃, and then performing open mixing. During the open mixing process, 3-4g of sulfur vulcanizing agent and 28-32g of rubber compounding agent are added, and the mixture is passed through a thin pass 4-6 times to obtain a uniform compound. The compound is then vulcanized at 140-150℃ with a positive vulcanization time of tc90 to obtain the modified aramid fiber reinforced styrene-butadiene rubber composite material.

[0014] Specifically, the aforementioned rubber composite material is prepared by impregnating 4g of modified aramid fiber, 200g of styrene-butadiene rubber matrix, and 80g of silica in a one-bath mixing process at 110-140℃ for 6-8 minutes, cooling to 60-80℃, and then performing open mixing. During the open mixing process, 3.4g of sulfur vulcanizing agent and 30.98g of rubber compounding agent are added. The mixture is passed through a thin tube 4-6 times to obtain a uniform compound. The compound is then vulcanized at 145℃ with a positive vulcanization time tc90 to obtain the modified aramid fiber reinforced styrene-butadiene rubber composite material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with the traditional RFL impregnation system, the impregnation system of the present invention has a significantly simplified process and a greatly improved production efficiency.

[0016] 2. HDI is unsealed at the mixing temperature, forming stable urea bonds with the amide groups of aramid fibers, and simultaneously constructing a crosslinking network with epoxy groups, thus strengthening the interfacial adhesion. GMA provides active double bonds and epoxy sites, both regulating the interfacial modulus and participating in rubber co-vulcanization to achieve chemical bonding. VP latex, as a flexible phase, improves interfacial energy matching and alleviates stress concentration. Compared to existing one-bath systems modified with single functional groups or with poor component compatibility, this invention achieves a triple synergy of "strong adhesion - efficient crosslinking - toughness regulation," enabling the fiber-rubber interface to possess both high strength and excellent peel resistance.

[0017] 3. By adjusting the amount of GMA added, the interfacial modulus and crosslinking density can be precisely adjusted to meet the performance requirements of composite materials in different scenarios. In mechanical property tests, the tensile strength and tear strength reached 18.2 MPa and 61 kN / m, respectively, the 100% constant elongation stress reached 6.39 MPa, and the 300% constant elongation stress reached 12.29 MPa. In H-extraction performance tests, the maximum extraction force reached a maximum of 187.2 N. Furthermore, in fatigue performance tests, when the GMA addition amount reached 10%, the fatigue life reached 43,902 cycles, while the fatigue life without GMA was only 11,392 cycles.

[0018] 4. Using deionized water as a solvent, there is no emission of volatile organic pollutants, which meets green production standards. Attached Figure Description

[0019] Figure 1 Comparison of mechanical properties of composite materials before and after modification (1 is Comparative Example 1; 2 is Comparative Example 2; 3 is Example 1; 4 is Example 2; 5 is Example 3; 6 is Example 4). Figure 2 Comparison of H-extraction performance test results before and after composite material modification (1 is Comparative Example 1; 2 is Comparative Example 2; 3 is Example 1; 4 is Example 2; 5 is Example 3; 6 is Example 4). Figure 3 Comparison chart of fatigue performance tests of composite materials (1 is Comparative Example 1; 2 is Comparative Example 2; 3 is Example 1; 4 is Example 2; 5 is Example 3; 6 is Example 4). Detailed Implementation

[0020] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention.

[0021] Reagents and raw materials: aramid fiber, epoxy resin E51, blocked hexamethylene diisocyanate (HDI), glycidyl methacrylate (GMA), deionized water and butyl-butadiene rubber latex (VP latex), styrene-butadiene rubber, silica, zinc oxide, stearic acid, accelerator M (2-mercaptobenzothiazole), accelerator D (diphenylguanidine), accelerator DM (dibenzothiazole disulfide), accelerator TMTD (tetramethylthiuram disulfide), antioxidant 4010 (4-isopropylaminodiphenylamine), sulfur vulcanizing agent.

[0022] Example 1: One-bath impregnation system without GMA 1. Preparation of one-bath impregnation modified aramid fibers (1) Preparation of one-bath impregnation solution: Weigh 60g of deionized water and place it in a stirring cup. Start magnetic stirring at 500rpm, add 3g of epoxy resin E51, and continue stirring for 15 minutes until it is evenly dispersed. Then add 7g of blocked hexamethylene diisocyanate (HDI) and continue stirring for 20 minutes to form a homogeneous system. Finally, slowly add 20g of butadiene-pyridine latex (VP latex), keep stirring at low speed for 10 minutes, let stand for 30 minutes to degas, and then add deionized water to a total mass of 100g to obtain a one-bath impregnation solution containing 0% GMA.

[0023] (2) Fiber impregnation and drying treatment: After cleaning 4g of aramid fiber with acetone, it is impregnated in 100g of one-bath impregnation solution containing 0% GMA for 10 minutes at room temperature to ensure that the fiber surface is fully wetted; after taking it out, use clean filter paper to wipe off the excess liquid on the surface, and place it in an 80℃ oven to dry for 10 minutes to remove the surface moisture, thus completing the one-bath impregnation treatment and obtaining one-bath impregnated modified aramid fiber containing 0% GMA.

[0024] 2. Preparation of modified aramid fiber reinforced styrene-butadiene rubber composites Weigh out 200g of styrene-butadiene rubber, 80g of silica, 30.98g of rubber compounding agent (composed of 10g of zinc oxide, 8g of stearic acid, 4.42g of accelerator M, 1g of accelerator D, 3.92g of accelerator DM, 0.64g of accelerator TMTD and 3g of antioxidant 4010), and 3.4g of sulfur vulcanizing agent.

[0025] Styrene-butadiene rubber, silica, and the one-bath impregnated modified aramid fiber prepared above were put into a mixer at 110-140°C and mixed for 6-8 minutes (this temperature allows the closed hexamethylene diisocyanate (HDI) to unblock and react); then the material was transferred to a two-roll mill at 60-80°C for mixing, sulfur vulcanizing agent and rubber compounding agent were added, and the mixture was passed through a thin mill 4-6 times to obtain a uniform compound; the compound was vulcanized according to the positive vulcanization time tc90 (vulcanization temperature of 145°C) determined by the vulcanizer to prepare a modified aramid fiber reinforced styrene-butadiene rubber composite material containing 0% GMA.

[0026] Example 2: One-bath impregnation system containing 5% GMA 1. Preparation of one-bath impregnation modified aramid fibers (1) Preparation of one-bath impregnation solution: Weigh 60g of deionized water into a stirring cup, start magnetic stirring at 500rpm, add 3g of epoxy resin E51 and 1.5g of glycidyl methacrylate (GMA), and continue stirring for 15 minutes until evenly dispersed; then add 7g of blocked hexamethylene diisocyanate (HDI), and stir for 20 minutes to form a homogeneous system; finally, slowly add 20g of butadiene-pyridine latex (VP latex), keep stirring at low speed for 10 minutes, let stand for 30 minutes to degas, and then add deionized water to a total mass of 100g to obtain a one-bath impregnation solution containing 5% GMA.

[0027] (2) Fiber impregnation and drying treatment: In the same way as step (2) in Example 1, 4g of aramid fiber was washed with acetone and then impregnated in 100g of one-bath impregnation solution containing 5% GMA at room temperature for 10 minutes and dried at 80°C for 10 minutes to obtain one-bath impregnated modified aramid fiber containing 5% GMA.

[0028] 2. Preparation of modified aramid fiber reinforced styrene-butadiene rubber composites The preparation steps of the modified aramid fiber reinforced styrene-butadiene rubber composite material are completely consistent with those in Example 1, except that the one-bath impregnation solution containing 0% GMA is replaced with a one-bath impregnation solution containing 5% GMA to modify the aramid fiber, and finally the modified aramid fiber reinforced styrene-butadiene rubber composite material containing 5% GMA is obtained.

[0029] Example 3: One-bath impregnation system containing 10% GMA 1. Preparation of one-bath impregnation modified aramid fibers (1) Preparation of one-bath impregnation solution: Weigh 60g of deionized water into a stirring cup, start magnetic stirring at 500rpm, add 3g of epoxy resin E51 and 3g of glycidyl methacrylate (GMA), and continue stirring for 15 minutes until evenly dispersed; then add 7g of blocked hexamethylene diisocyanate (HDI), and stir for 20 minutes to form a homogeneous system; finally, slowly add 20g of butadiene-pyridine latex (VP latex), keep stirring at low speed for 10 minutes, let stand for 30 minutes to degas, and then add deionized water to a total mass of 100g to obtain a one-bath impregnation solution containing 10% GMA.

[0030] (2) Fiber impregnation and drying treatment: In the same way as step (2) in Example 1, 4g of aramid fiber was washed with acetone and then impregnated in 100g of one-bath impregnation solution containing 10% GMA at room temperature for 10 minutes and dried at 80°C for 10 minutes to obtain one-bath impregnated modified aramid fiber containing 10% GMA.

[0031] 2. Preparation of modified aramid fiber reinforced styrene-butadiene rubber composites The preparation steps of the modified aramid fiber reinforced styrene-butadiene rubber composite material are completely consistent with those in Example 1, except that the one-bath impregnation solution containing 0% GMA is replaced with a one-bath impregnation solution containing 10% GMA to modify aramid fibers, and finally the modified aramid fiber reinforced styrene-butadiene rubber composite material containing 10% GMA is obtained.

[0032] Example 4: One-bath impregnation system containing 15% GMA 1. Preparation of one-bath impregnation modified aramid fibers (1) Preparation of one-bath impregnation solution: Weigh 60g of deionized water into a stirring cup, start magnetic stirring at 500rpm, add 3g of epoxy resin E51 and 4.5g of glycidyl methacrylate (GMA), and continue stirring for 15 minutes until evenly dispersed; then add 7g of blocked hexamethylene diisocyanate (HDI), and stir for 20 minutes to form a homogeneous system; finally, slowly add 20g of butadiene-pyridine latex (VP latex), keep stirring at low speed for 10 minutes, let stand for 30 minutes to degas, and then add deionized water to a total mass of 100g to obtain a one-bath impregnation solution containing 15% GMA.

[0033] (2) Fiber impregnation and drying treatment: In the same way as step (2) in Example 1, 4g of aramid fiber was washed with acetone and then impregnated in 100g of one-bath impregnation solution containing 15% GMA at room temperature for 10 minutes and dried at 80°C for 10 minutes to obtain one-bath impregnated modified aramid fiber containing 15% GMA.

[0034] 2. Preparation of modified aramid fiber reinforced styrene-butadiene rubber composites The preparation steps of the modified aramid fiber reinforced styrene-butadiene rubber composite material are completely consistent with those in Example 1, except that the one-bath impregnation solution containing 0% GMA is replaced with a one-bath impregnation solution containing 15% GMA to modify aramid fibers, and finally the modified aramid fiber reinforced styrene-butadiene rubber composite material containing 15% GMA is obtained.

[0035] Comparative Example 1: Preparation of pure styrene-butadiene rubber composite material Preparation method of pure styrene-butadiene rubber composite material: Weigh 200g styrene-butadiene rubber, 80g silica, 31g rubber compounding agent (composed of 10g zinc oxide, 8g stearic acid, 4.42g accelerator M, 1g accelerator D, 3.92g accelerator DM, 0.64g accelerator TMTD and 3g antioxidant 4010), and 3.4g sulfur vulcanizing agent. Add the styrene-butadiene rubber and silica to a mixer at 110-140℃ and mix for 6-8 minutes; then transfer to a two-roll mill at 60-80℃ and mix, adding the sulfur vulcanizing agent and rubber compounding agent, passing through a thin mill 4-6 times to obtain a compound; vulcanize the compound according to the positive vulcanization time tc90 determined by a vulcanizing apparatus to prepare pure styrene-butadiene rubber composite material (without aramid fiber reinforcement).

[0036] Comparative Example 2: Unmodified aramid fiber / styrene-butadiene rubber composite material Preparation method of unmodified aramid fiber / styrene-butadiene rubber composite material: Weigh 200g styrene-butadiene rubber, 80g silica, 4g unmodified aramid fiber (used directly after acetone washing, without impregnation modification treatment), 31g rubber compounding agent (composed of 10g zinc oxide, 8g stearic acid, 4.42g accelerator M, 1g accelerator D, 3.92g accelerator DM, 0.64g accelerator TMTD and 3g antioxidant 4010), and 3.4g sulfur vulcanizing agent. Add styrene-butadiene rubber, silica, and unmodified aramid fiber to a Banbury mixer at 110-140℃ and mix for 6-8 minutes; then transfer to a two-roll mill at 60-80℃ and mix, adding sulfur vulcanizing agent and rubber compounding agent, passing through a thin mill 4-6 times to obtain a compound; vulcanize the compound according to the positive vulcanization time tc90 determined by a vulcanizer to prepare the unmodified aramid fiber reinforced styrene-butadiene rubber composite material.

[0037] The mechanical properties of various styrene-butadiene rubber composites prepared by the methods in Examples 1-4 and Comparative Examples 1-2 were tested, including extraction performance tests and fatigue performance tests. The results of the experimental research of this invention are as follows: 1. Mechanical property testing: such as Figure 1Samples 1, 2, 3, 4, 5, and 6 represent Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4, respectively. Compared to Comparative Example 1 and Comparative Example 2, the overall mechanical properties of the Examples were improved. After modification with the impregnation system, the tensile strength and tear strength of the styrene-butadiene rubber composite material continuously increased with the increase of GMA content, reaching the highest point in Example 3, with a tensile strength of 18.2 MPa and a tear strength of 61 kN / m. Example 4, however, experienced a decline in performance due to material embrittlement caused by excessive crosslinking. Simultaneously, the 100% and 300% tensile stresses of the composite material also showed similar trends, initially increasing and then decreasing with the increase of GMA content. Example 3 exhibited the highest tensile stress, reaching 6.39 MPa and 12.29 MPa, respectively, indicating that the crosslinking density of the composite material was continuously increasing. In summary, through the impregnation solution modification designed in this experiment, Example 3 demonstrated the best overall mechanical properties.

[0038] 2. H extraction performance test: such as Figure 2 Samples 1, 2, 3, 4, 5, and 6 are Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4, respectively. It can be seen that compared to Comparative Example 2, the H-pull-out force of the modified styrene-butadiene rubber composite material is significantly improved, indicating that the double-layer impregnation system prepared in this experiment has better interfacial adhesion. Among them, Example 3 achieved the highest H-pull-out force of 187.2 N.

[0039] 3. Fatigue performance testing: such as Figure 3Samples 1, 2, 3, 4, 5, and 6 are Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4, respectively. A dynamic fatigue testing machine was used under load control conditions, with an initial load of 27 N, an amplitude of 13 N, and a frequency of 5 Hz, applied as a sinusoidal wave. Tensile fatigue tests were conducted on each group of composite materials under the above conditions to obtain the fatigue tensile cycle data. Compared to Comparative Examples 1 and 2, the modified styrene-butadiene rubber composite material showed a significant increase in fatigue cycles. This is because the fibers were not modified, the aramid fiber surface is chemically inert, and styrene-butadiene rubber is a non-polar rubber. There is a significant difference in interfacial compatibility between the aramid fiber and the rubber matrix, resulting in poor interfacial bonding and a very short fatigue life, making it prone to rapid failure under cyclic stress loading. The fatigue lives of samples in Examples 1, 2, 3, and 4 were 11392, 21679, 43902, and 36230 cycles, respectively. With increasing GMA content, the fatigue life of the composite material also increased. This is because the composite material with superior fatigue performance was obtained through impregnation treatment. The principle is that the impregnation treatment creates a gradient interface layer at the fiber-rubber interface, which enhances stress transmission and dissipates strain energy during fatigue cycles, thus inhibiting rapid crack propagation. However, when the GMA content reaches 4.5g, the fatigue life of the composite material decreases compared to Example 3. This is due to the increased curing agent content in the impregnation solution, resulting in excessive cross-linking of the impregnation layer.

Claims

1. A method for modifying aramid fibers by one-bath impregnation, characterized in that: The modification method involves first mixing epoxy resin E51, glycidyl methacrylate, blocked hexamethylene diisocyanate, and butadiene-pyridine latex in an aqueous phase to form a one-bath impregnation solution. Aramid fibers are then added to the one-bath impregnation solution to modify the aramid fibers through one-bath impregnation. After impregnation, the fibers are dried to obtain one-bath impregnated modified aramid fibers.

2. The modification method for one-bath impregnation of modified aramid fibers according to claim 1, characterized in that: The modification method is carried out according to the following steps: (1) Preparation of one-bath impregnation solution: Take 55-65g of deionized water, start magnetic stirring at 400-600rpm, add 2.5-3.5g of epoxy resin E51 and 1.5-4.5g of glycidyl methacrylate, and continue stirring for 10-20 minutes until evenly dispersed; then add 6.5-7.5g of blocked hexamethylene diisocyanate, and stir for 18-22 minutes to form a homogeneous system; finally, slowly add 18-22g of butadiene-pyridine latex, keep stirring at low speed for 8-12 minutes, let stand for 25-35 minutes to degas, and then add deionized water to a total mass of 100g to obtain one-bath impregnation solution; (2) Aramid fiber modification treatment: 3.5-4.5g of aramid fiber, after being cleaned and dried with acetone, is immersed in the one-bath impregnation solution prepared in step (1) for 8-12 minutes at room temperature. After taking it out, the excess liquid on the surface is wiped off with clean filter paper, and then placed in an oven at 75-85℃ to dry for 8-12 minutes to remove surface moisture. The one-bath impregnation treatment is completed, and one-bath impregnated modified aramid fiber is obtained.

3. The modification method for one-bath impregnation of modified aramid fibers according to claim 2, characterized in that: In step (1), the preparation of the one-bath impregnation solution is as follows: Take 60g of deionized water, start magnetic stirring at 500rpm, add 3g of epoxy resin E51 and 3g of glycidyl methacrylate, and continue stirring for 15 minutes until evenly dispersed; then add 7g of blocked hexamethylene diisocyanate, and stir for 20 minutes to form a homogeneous system; finally, slowly add 20g of butadiene-pyridine latex, keep stirring at low speed for 10 minutes, let stand for 30 minutes to degas, and then add deionized water to a total mass of 100g to obtain the one-bath impregnation solution.

4. The modification method for one-bath impregnation of modified aramid fibers according to claim 2, characterized in that: In step (2), the aramid fiber is modified by immersing 4g of aramid fiber, which has been cleaned and dried with acetone, in 100g of one-bath impregnation solution prepared in step (1) for 10 minutes at room temperature. After taking it out, use clean filter paper to gently wipe off the excess liquid on the surface, and place it in an 80℃ oven to dry for 10 minutes to remove the surface moisture. The one-bath impregnation process is completed to obtain one-bath impregnated modified aramid fiber.

5. The application of the one-bath impregnation modified aramid fiber according to any one of claims 1 to 4 in the preparation of rubber composite materials, characterized in that: The rubber composite material is prepared by one-bath impregnation of modified aramid fibers and styrene-butadiene rubber matrix through mixing, open milling, and vulcanization.

6. The application according to claim 5, characterized in that: The raw materials of the rubber composite material, calculated by weight, consist of 180-220 parts of styrene-butadiene rubber, 3-5 parts of one-bath impregnated modified aramid fiber, 75-85 parts of silica, 28-32 parts of rubber compounding agent, and 3-4 parts of sulfur vulcanizing agent; the rubber compounding agent consists of 8-12 parts of zinc oxide, 6-10 parts of stearic acid, 4-5 parts of accelerator M, 0.8-1.2 parts of accelerator D, 3.5-4.5 parts of accelerator DM, 0.5-0.8 parts of accelerator TMTD, and 2.5-3.5 parts of antioxidant 4010.

7. The application according to claim 6, characterized in that: The raw materials of the rubber composite material, calculated by weight, consist of 200 parts of styrene-butadiene rubber, 4 parts of one-bath impregnated modified aramid fiber, 80 parts of silica, 30.98 parts of rubber compounding agent, and 3.4 parts of sulfur vulcanizing agent; the rubber compounding agent consists of 10 parts of zinc oxide, 8 parts of stearic acid, 4.42 parts of accelerator M, 1 part of accelerator D, 3.92 parts of accelerator DM, 0.64 parts of accelerator TMTD, and 3 parts of antioxidant 4010.

8. The application according to claim 5, characterized in that: The method for preparing the rubber composite material is as follows: 3-5 parts of modified aramid fiber, 180-220g of styrene-butadiene rubber matrix, and 75-85g of silica are impregnated in a one-bath mixture and then internally mixed at 110-140℃ for 6-8 minutes. After cooling to 60-80℃, the mixture is then subjected to open mixing. During the open mixing process, 3-4g of sulfur vulcanizing agent and 28-32g of rubber compounding agent are added. The mixture is passed through a thin pass 4-6 times to obtain a uniform compound. The compound is then vulcanized at 140-150℃ with a positive vulcanization time tc90 to prepare the modified aramid fiber reinforced styrene-butadiene rubber composite material.

9. The application according to claim 8, characterized in that: The preparation method of the rubber composite material is as follows: 4g of modified aramid fiber, 200g of styrene-butadiene rubber matrix and 80g of silica are impregnated in a one-bath mixture and then mixed at 110-140℃ for 6-8 minutes. After cooling to 60-80℃, the mixture is subjected to open mixing. During the open mixing process, 3.4g of sulfur vulcanizing agent and 30.98g of rubber compounding agent are added. The mixture is passed through a thin tube 4-6 times to obtain a uniform compound. The compound is then vulcanized at 145℃ with a positive vulcanization time tc90 to obtain the modified aramid fiber reinforced styrene-butadiene rubber composite material.

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