Aramid-rubber in-situ composite master batch, and preparation method and application thereof

Abstract

This invention relates to the field of aramid-rubber composite materials, specifically to an aramid-rubber in-situ composite masterbatch, its preparation method, and its application. The preparation method involves: dissolving rubber raw materials in an organic solvent to obtain a rubber solution; mixing the rubber solution with an aramid precipitate fiber polymerization solution to obtain an aramid-rubber blend solution; injecting the aramid-rubber blend solution into a coagulation bath under high-speed stirring for co-precipitation, causing the aramid to precipitate and crystallize in situ, settling simultaneously with the rubber to obtain an aramid-rubber precipitate; and washing, drying, and granulating the precipitate to obtain the aramid-rubber in-situ composite masterbatch. This invention solves the problems of difficult dispersion, easy agglomeration, and weak interfacial bonding of aramid pulp or short fibers in a rubber matrix in existing technologies. It simultaneously achieves uniform dispersion of aramid fibers, strong interfacial bonding, and one-step masterbatch formation without the need for a release agent. The process is simple, efficient, and suitable for industrial-scale production.

Description

Technical Field

[0001] This invention relates to an in-situ aramid-rubber composite masterbatch, its preparation method, and its application, belonging to the technical field of aramid-rubber composite materials. Background Technology

[0002] Aramid-reinforced rubber composites, especially those reinforced with aramid pulp or short fibers, are widely used in high-end tires, seals, and friction materials due to their high strength, modulus, and wear resistance. However, because of the high rigidity and surface polarity of aramid molecular chains, aramid pulp is prone to agglomeration in the rubber matrix, forming unevenly dispersed hard spots that severely affect the mechanical properties and processing experience of the composite material. Therefore, achieving uniform dispersion of aramid fibers in the rubber matrix and establishing good interfacial bonding has become a key technical problem restricting the development of high-end aramid-rubber composites.

[0003] Currently, the industry commonly uses the dry powder mixing method, which involves first drying and pulverizing aramid pulp, then mechanically mixing it into the rubber matrix using an internal mixer. This method has low equipment investment and a simple process, but due to the large specific surface area of ​​aramid pulp and the strong hydrogen bonding between fibers, it is difficult to achieve uniform dispersion during mechanical mixing, easily leading to agglomerates. This not only reduces the mechanical properties of the product but also easily causes equipment wear and filter clogging in subsequent processing. To solve these dispersion problems, researchers have proposed various improvement schemes, among which emulsion blending and solution blending methods have received the most attention.

[0004] DuPont's Kevlar® EE series is a typical example of an emulsion blending product, which blends aramid pulp with rubber latex to prepare aramid pulp masterbatch. Compared to dry powder mixing, this method reduces the introduction of release agents to some extent and allows for the preparation of dispersions of different latex types according to the final rubber compound requirements. However, this method involves the use of a large amount of aqueous phase and emulsifier, has a long processing flow, complex and energy-intensive solvent removal and recovery processes, and residual emulsifiers and moisture in the product may adversely affect the performance of the vulcanizate.

[0005] Regarding solution blending, patent application PCT / US94 / 03991 proposes a method of dissolving elastomer rubber in an organic solvent and then adding aramid pulp for mixing. While this method theoretically allows for a higher proportion of aramid added, it still cannot effectively solve the problem of difficult dispersion of aramid pulp in solution. Because the aramid pulp remains in the form of micron-sized aggregates when added to the solution, it is difficult to break it down to the individual fiber level during stirring and dispersion, resulting in uneven fiber dispersion in the final product. Furthermore, this type of method generally faces difficulties in removing and recovering large amounts of organic solvent, hindering its industrial application.

[0006] Furthermore, patent application CN1896369A discloses a pretreatment method for para-aramid pulp, which uses hollow glass microspheres as a separating agent mixed with the aramid pulp, followed by treatment with phthalate ester lubricants. While this method improves the looseness of the pulp to some extent, it introduces a large amount of additives, increasing the complexity of the formulation. Moreover, the residue of the inorganic separating agent may cause interface defects and heat generation problems during later vulcanization, which is detrimental to the overall performance of the composite material.

[0007] In summary, existing technologies, whether dry powder mixing, emulsion blending, or solution blending, all suffer from the following common drawbacks: First, they all use pre-formed aramid pulp or short fibers as raw materials, making it difficult to effectively break up the inherent agglomerates of the fibers during subsequent mixing. Second, the interfacial bonding between aramid and the rubber matrix is ​​weak, requiring the use of coupling agents or separating agents for improvement. Third, the process consumes a lot of energy, and solvent recovery is difficult, making it hard to achieve green and efficient industrial production. Therefore, developing a novel aramid-rubber composite masterbatch preparation method that can eliminate aramid agglomeration at the source, achieve simultaneous composite of fibers and rubber matrix, and has a simple and efficient process has significant industrial application value. Summary of the Invention

[0008] This invention addresses the shortcomings of existing technologies by providing an aramid-rubber in-situ composite masterbatch, its preparation method, and its applications. It solves the problems of difficult dispersion, easy agglomeration, and weak interfacial bonding of aramid pulp or short fibers in a rubber matrix. By in-situ liquid-phase blending of the aramid precipitated fiber polymerization solution with a rubber solution, and employing a co-precipitation process to allow aramid to precipitate and crystallize in-situ within the rubber matrix, uniform dispersion of aramid fibers, strong interfacial bonding, and one-step masterbatch formation are simultaneously achieved. No separating agent is required, making the process simple, efficient, and suitable for industrial-scale production.

[0009] The technical solution of this invention to solve the above-mentioned technical problems is as follows: a method for preparing aramid-rubber in-situ composite masterbatch, wherein the preparation method is as follows: S1. Dissolve the rubber raw material in an organic solvent to obtain a rubber solution; S2. The rubber solution is mixed with the aramid precipitated fiber polymerization solution in the liquid phase to obtain an aramid rubber blend solution; S3. The aramid rubber blend solution is injected into a coagulation bath under high-speed stirring to co-precipitate, so that the aramid crystallizes into fibers in situ and settles synchronously with the rubber to obtain aramid rubber precipitate. S4. The precipitate is washed, dried and granulated to obtain aramid-rubber in-situ composite masterbatch.

[0010] Furthermore, the organic solvent mentioned in step S1 is consistent with the solvent system of the aramid precipitated fiber polymerization solution.

[0011] Furthermore, the organic solvent is N-methylpyrrolidone.

[0012] Furthermore, the rubber raw material is nitrile rubber and / or hydrogenated nitrile rubber, and the acrylonitrile content in the rubber raw material is ≥40%.

[0013] Furthermore, the solid content of the rubber solution in step S1 is 5%-10%; The solid content of the aramid precipitated fiber polymerization solution in step S2 is 3-5%.

[0014] Furthermore, the dissolution temperature in step S1 is 80-130℃, and the stirring speed is 300-500 r / min; The stirring speed for liquid phase mixing in step S2 is 400-600 r / min, and the stirring time is 30-60 min.

[0015] Furthermore, in the aramid rubber blend solution, the aramid precipitated fiber polymer accounts for 10%-30% of the total weight of the rubber raw material and the aramid precipitated fiber polymer.

[0016] Furthermore, the high-speed stirring speed in step S3 is 1000-3000 r / min.

[0017] Furthermore, the coagulation bath comprises water and ethanol, with a volume ratio of water to ethanol of 1:(15-25).

[0018] The present invention also discloses an aramid-rubber in-situ composite masterbatch, wherein the aramid-rubber in-situ composite masterbatch is prepared by the preparation method described in the present invention.

[0019] The present invention also discloses an application of an aramid-rubber in-situ composite masterbatch, wherein the aramid-rubber in-situ composite masterbatch is applied to rubber composite materials.

[0020] The beneficial effects of this invention are: This invention provides an in-situ aramid-rubber composite masterbatch and its preparation method. The method replaces the pre-formed aramid pulp or short fibers with an aramid precipitate fiber polymerization solution, and performs in-situ liquid-phase blending and simultaneous co-precipitation with a nitrile rubber solution. This allows the aramid to precipitate and form fibers in situ within the rubber matrix, achieving uniform fiber dispersion, strong interfacial bonding, and masterbatch formation in one step. This solution solves the problems of difficult aramid dispersion in rubber, weak interfacial bonding, complex processes, and high dependence on additives. Specific beneficial effects are as follows: (1) Excellent dispersibility. In the prior art, aramid pulp or short fibers have formed macroscopic fibers after spinning and cutting. Due to hydrogen bonding, the fibers are tightly aggregated and it is difficult to break them down to the single fiber level through subsequent mechanical stirring or blending. The present invention uses aramid precipitation fiber polymerization solution, so that aramid enters the system directly in the form of molecular chains and achieves molecular-level blending with rubber solution in the liquid phase. After being injected into the coagulation bath, aramid precipitates and forms fibers at the same time as rubber precipitates. The newly formed fibers are instantaneously dispersed and wrapped in the rubber matrix under shear action. They are fixed in an isolated state from the moment of fiber formation, which fundamentally avoids fiber agglomeration.

[0021] (2) Strong interfacial bonding, no coupling agent required. In the prior art, the interfacial bonding between aramid and rubber is weak, and coupling agents are usually added to improve it. In this invention, the aramid precipitation fiber polymerization solution and nitrile rubber (acrylonitrile content ≥40%) share the same NMP solvent system. The two polar polymers fully contact each other in the liquid phase and form interchain entanglement. During simultaneous precipitation, the rubber macromolecules are deposited and wrapped in situ on the surface of the nascent aramid fiber, forming a dual interfacial bonding of physical entanglement and polar interaction. The surface of the nascent fiber is not dried or contaminated by processing and has high activity. The interfacial bonding is better than the mechanical interlocking method of first making the fiber and then blending, and no additional coupling agent is required.

[0022] (3) The process is simplified and suitable for industrial production. After the aramid raw material and the rubber solution are mixed at the molecular level in the liquid state, the composite masterbatch is obtained by one-step co-precipitation, which eliminates the many processes in the traditional process, such as drying and crushing of aramid pulp, pre-dispersion, open milling, and internal mixing, which significantly reduces energy consumption and equipment investment. At the same time, the NMP solvent and water / ethanol coagulation bath can be recovered and recycled through conventional distillation, which meets the requirements of green production. Attached Figure Description

[0023] Figure 1 The image shows an electron microscope image of the aramid / rubber composite material prepared in Example 1. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0026] A method for preparing an aramid-rubber in-situ composite masterbatch, wherein the preparation method comprises: S1. Dissolve the rubber raw material in an organic solvent to obtain a rubber solution; S2. The rubber solution is mixed with the aramid precipitated fiber polymerization solution in the liquid phase to obtain an aramid rubber blend solution; S3. The aramid rubber blend solution is injected into a coagulation bath under high-speed stirring to co-precipitate, so that the aramid crystallizes into fibers in situ and settles synchronously with the rubber to obtain aramid rubber precipitate. S4. The precipitate is washed, dried and granulated to obtain aramid-rubber in-situ composite masterbatch.

[0027] Specifically, the organic solvent in step S1 is the same as the solvent system of the aramid precipitated fiber polymerization solution.

[0028] Specifically, the organic solvent is N-methylpyrrolidone. This organic solvent is consistent with the solvent in the aramid precipitation polymerization solution to prevent precipitation of the aramid precipitation polymerization solution when the rubber solution is added in step S2 due to differences in solvent solubility.

[0029] Specifically, the rubber raw material is nitrile butadiene rubber (NBR) and / or hydrogenated nitrile butadiene rubber (HNBR), and the acrylonitrile content in the rubber raw material is ≥40%.

[0030] Specifically, the solid content of the rubber solution in step S1 is 5%-10%; The solid content of the aramid precipitated fiber polymerization solution in step S2 is 3-5%.

[0031] Preferably, the solid content of the rubber solution in step S1 is 10%; and the solid content of the aramid precipitated fiber polymerization solution in step S2 is 4%.

[0032] Specifically, in step S1, the dissolution temperature is 80-130℃, and the stirring speed is 300-500 r / min; The stirring speed for liquid phase mixing in step S2 is 400-600 r / min, and the stirring time is 30-60 min.

[0033] Specifically, in the aramid rubber blend solution, the aramid precipitated fiber polymer accounts for 10%-30% of the total weight of the rubber raw material and the aramid precipitated fiber polymer.

[0034] Specifically, the high-speed stirring speed in step S3 is 1000-3000 r / min.

[0035] Specifically, the coagulation bath comprises water and ethanol, with a volume ratio of water to ethanol of 1:(15-25).

[0036] An aramid-rubber in-situ composite masterbatch is prepared by the preparation method described in this invention.

[0037] An application of an aramid-rubber in-situ composite masterbatch, wherein the aramid-rubber in-situ composite masterbatch is applied to rubber composite materials.

[0038] More specifically, in this embodiment of the invention, the preparation method of the rubber composite material is as follows: HNBR / NBR rubber, carbon black, and aramid-rubber in-situ composite masterbatch are mixed in an internal mixer at a temperature not exceeding 80°C. Then, ZnO, stearic acid, and plasticizer are added to the internal mixer and mixed uniformly to obtain the mixed rubber. The mixed rubber is then cooled to 25-30°C. The cooled mixed rubber is then milled on a two-roll mill, with BIPB-40 and TAIC-70 added, and the milling temperature controlled not to exceed 50°C, so that the vulcanizing agent and the mixed rubber are mixed uniformly into sheets. After sheeting, the sheets are hot-pressed at 170°C and 5MPa using an 80-ton flat vulcanizing apparatus to obtain the rubber composite material. However, the process conditions of this application method do not constitute a limitation of the invention.

[0039] More specifically, the aramid precipitation polymerization stock solution used in this embodiment of the invention is self-made, wherein the solid content of the para-aramid polymer is 4% (the solvent is N-methylpyrrolidone). The specific preparation method is as follows: NMP and CaCl2 are mixed, and p-phenylenediamine is added under a nitrogen atmosphere for dissolution. Then, terephthaloyl chloride is added at a low temperature (-5~0℃) for pre-condensation, wherein the molar ratio of p-phenylenediamine to terephthaloyl chloride is 1:0.6. After the pre-condensation is completed, terephthaloyl chloride is added and stirred vigorously to carry out the condensation reaction. The molar ratio of the added terephthaloyl chloride to the p-phenylenediamine in the system is 0.4:1. Stirring is stopped when colloid is formed, and the mixture is aged at 50-80℃ under a nitrogen atmosphere to obtain the aramid precipitation polymerization stock solution.

[0040] Example 1: Preparation of aramid-rubber in-situ composite masterbatch and rubber composite material.

[0041] (1) This embodiment provides a method for preparing aramid-rubber in-situ composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Rueon Company, ZP0020, acrylonitrile content of 50%), add it to 450g of NMP (N-methylpyrrolidone) solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely transparent, to obtain a rubber solution with a solid content of 10%.

[0042] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 312.5g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 20%.

[0043] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:20) under high-speed stirring at 3000 r / min to obtain aramid rubber precipitate.

[0044] S4. Granulation: The precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber in-situ composite masterbatch.

[0045] (2) This embodiment provides a method for preparing a rubber composite material. The specific preparation process is as follows: Compound formulation: 200g HNBR rubber (the same rubber raw material used in step S1 of this embodiment), 100g carbon black, and 20g aramid-rubber in-situ composite masterbatch prepared in this embodiment. The above components are mixed in a Banbury mixer, with the temperature controlled not to exceed 80℃; then 10g ZnO, 2g stearic acid, and 10g plasticizer TOTM are added, and mixing continues until uniform to obtain the mixed rubber. The mixed rubber is removed and allowed to cool to 30℃; then it is milled on a two-roll mill, with 16g BIPB-40 and 4g TAIC-70 added, controlling the milling temperature not to exceed 50℃, so that the vulcanizing agent and the mixed rubber are mixed uniformly into sheets. After sheeting, an 80-ton flat vulcanizing apparatus is used for hot pressing at 170℃ and 5 MPa to obtain the rubber composite material.

[0046] Example 2: Preparation of aramid-rubber in-situ composite masterbatch and rubber composite material.

[0047] (1) This embodiment provides a method for preparing aramid-rubber in-situ composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of nitrile rubber (NBR, Rion Corporation, DN003, acrylonitrile content of 50%), add it to 450g of NMP solvent, and dissolve it at 120℃ with a stirring speed of 400 r / min until it is completely transparent, to obtain a rubber solution with a solid content of 10%.

[0048] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 312.5g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 20%.

[0049] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:20) under high-speed stirring at 3000 r / min to obtain aramid fiber / rubber precipitate.

[0050] S4. Granulation: The precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber in-situ composite masterbatch.

[0051] (2) This embodiment provides a method for preparing a rubber composite material. The specific preparation process is as follows: Compound formulation: 200g NBR rubber (same as the rubber raw material used in step S1 of this embodiment), 100g carbon black, and 20g aramid-rubber in-situ composite masterbatch prepared in this embodiment. The above components are mixed in a Banbury mixer, with the temperature controlled not to exceed 80℃; then 10g ZnO, 2g stearic acid, and 10g plasticizer TOTM are added, and mixing continues until uniform to obtain the mixed rubber. The mixed rubber is removed and allowed to cool to 30℃; then it is milled on a two-roll mill, with 6g BIPB-40 and 4g TAIC-70 added, controlling the milling temperature not to exceed 50℃, so that the vulcanizing agent and the mixed rubber are mixed uniformly into sheets. After sheeting, an 80-ton flat vulcanizing apparatus is used for hot pressing at 170℃ and 5 MPa to obtain the rubber composite material.

[0052] Example 3: Preparation of aramid-rubber in-situ composite masterbatch and rubber composite material.

[0053] (1) This embodiment provides a method for preparing aramid-rubber in-situ composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Ruwen Company, ZP0020, acrylonitrile content of 50%), add it to 950g of NMP (N-methylpyrrolidone) solvent, and dissolve it at 80℃ with a stirring speed of 500r / min until it is completely transparent, to obtain a rubber solution with a solid content of 5%.

[0054] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 1250g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 600r / min for 30min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 30%.

[0055] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:25) under high-speed stirring at 2000 r / min to obtain aramid rubber precipitate.

[0056] S4. Granulation: The precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber in-situ composite masterbatch.

[0057] (2) This embodiment provides a method for preparing a rubber composite material. The specific preparation process is as follows: Compound formulation: 200g HNBR rubber (the same rubber raw material used in step S1 of this embodiment), 100g carbon black, and 20g aramid-rubber in-situ composite masterbatch prepared in this embodiment. The above components are mixed in a Banbury mixer, with the temperature controlled not to exceed 80℃; then 10g ZnO, 2g stearic acid, and 10g plasticizer TOTM are added, and mixing continues until uniform to obtain the mixed rubber. The mixed rubber is removed and allowed to cool to 30℃; then it is milled on a two-roll mill, with 16g BIPB-40 and 4g TAIC-70 added, controlling the milling temperature not to exceed 50℃, so that the vulcanizing agent and the mixed rubber are mixed uniformly into sheets. After sheeting, an 80-ton flat vulcanizing apparatus is used for hot pressing at 170℃ and 5 MPa to obtain the rubber composite material.

[0058] Example 4: Preparation of aramid-rubber in-situ composite masterbatch and rubber composite material.

[0059] (1) This embodiment provides a method for preparing aramid-rubber in-situ composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of nitrile rubber (NBR, Rion Corporation, DN003, acrylonitrile content of 50%), add it to 450g of NMP solvent, and dissolve it at 120℃ with a stirring speed of 400 r / min until it is completely transparent, to obtain a rubber solution with a solid content of 10%.

[0060] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 140g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 10.07%.

[0061] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:15) under high-speed stirring at 1000 r / min to obtain aramid fiber / rubber precipitate.

[0062] S4. Granulation: The precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber in-situ composite masterbatch.

[0063] (2) This embodiment provides a method for preparing a rubber composite material. The specific preparation process is as follows: Compound formulation: 200g NBR rubber (same as the rubber raw material used in step S1 of this embodiment), 100g carbon black, and 20g aramid-rubber in-situ composite masterbatch prepared in this embodiment. The above components are mixed in a Banbury mixer, with the temperature controlled not to exceed 80℃; then 10g ZnO, 2g stearic acid, and 10g plasticizer TOTM are added, and mixing continues until uniform to obtain the mixed rubber. The mixed rubber is removed and allowed to cool to 30℃; then it is milled on a two-roll mill, with 6g BIPB-40 and 4g TAIC-70 added, controlling the milling temperature not to exceed 50℃, so that the vulcanizing agent and the mixed rubber are mixed uniformly into sheets. After sheeting, an 80-ton flat vulcanizing apparatus is used for hot pressing at 170℃ and 5 MPa to obtain the rubber composite material.

[0064] Comparative Example 1: Preparation of aramid-rubber in-situ composite masterbatch.

[0065] Aramid-rubber in-situ composite masterbatch was prepared using the same method as in Example 2, except that the solvent used in step S1 of Comparative Example 1 was industrial xylene, and other process conditions were the same as in Example 2. The specific preparation process is as follows: S1. Preparation of rubber solution: Weigh 50g of nitrile rubber (NBR, Rion Company, DN003, acrylonitrile content of 50%), add it to 450g of industrial xylene solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely dissolved, to obtain a rubber solution with a solid content of 10%.

[0066] Preparation of S2, aramid rubber blend solution: The rubber solution prepared in step S1 was poured into a reaction vessel, and 312.5g of aramid precipitate fiber polymerization stock solution (self-made, para-aramid solid content 4%) was slowly added while stirring. After the addition was complete, stirring was continued at 400r / min for 60min. During the stirring process, it was found that para-aramid precipitated in industrial xylene solvent, and the two solutions could not be mixed, making subsequent operations impossible.

[0067] Comparative Example 2: Preparation of aramid-rubber in-situ composite masterbatch.

[0068] Aramid-rubber in-situ composite masterbatch was prepared using the same method as in Example 1, except that the solvent used in step S1 of Comparative Example 2 was acetone, and other process conditions were the same as in Example 1. The specific preparation process is as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Rueon Company, ZP0020, acrylonitrile content of 50%), add it to 450g of acetone solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely dissolved, to obtain a rubber solution with a solid content of 10%.

[0069] Preparation of S2, aramid rubber blend solution: The rubber solution prepared in step S1 was poured into a reaction vessel, and 312.5g of aramid precipitate fiber polymerization stock solution (self-made, para-aramid solid content 4%) was slowly added while stirring. After the addition was complete, stirring was continued at 400r / min for 60min. During the stirring process, it was found that para-aramid precipitated in acetone solvent, and the two solutions could not be mixed, making subsequent operations impossible.

[0070] Comparative Example 3: Preparation of aramid-rubber in-situ composite masterbatch.

[0071] Aramid-rubber in-situ composite masterbatch was prepared using the same method as in Example 2, except that the acrylonitrile content in the rubber raw material used in Comparative Example 3 was <40%. Other process conditions were the same as in Example 2, and the specific preparation process is as follows: S1. Preparation of rubber solution: Weigh 50g of nitrile rubber (NBR, Rion Corporation, N41, acrylonitrile content of 29%) and add it to 450g of NMP solvent. Dissolve it at 120℃ with a stirring speed of 400 r / min. During the stirring process, it was found that NBR was difficult to dissolve and could not form a homogeneous and stable solution system.

[0072] Comparative Example 4: Preparation of aramid-rubber in-situ composite masterbatch.

[0073] Aramid-rubber in-situ composite masterbatch was prepared using the same method as in Example 1, except that the acrylonitrile content in the rubber raw material used in Comparative Example 4 was <40%. Other process conditions were the same as in Example 1, and the specific preparation process is as follows: S1. Preparation of rubber solution: Weigh 50g of nitrile rubber (HNBR, Reion Corporation, 2000L, acrylonitrile content 36%) and add it to 450g of NMP solvent. Dissolve it at 120℃ with a stirring speed of 400 r / min. During the stirring process, it was found that HNBR was difficult to dissolve and could not form a homogeneous and stable solution system.

[0074] Comparative Example 5: Preparation of aramid-rubber composite masterbatch and rubber composite material.

[0075] Aramid-rubber composite masterbatch was prepared using the same method as in Example 1, except that the coagulation bath used in step S3 of Comparative Example 5 was pure water, and the other process conditions were the same as in Example 1. The specific preparation process is as follows.

[0076] (1) A method for preparing an aramid-rubber composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Ruwen Company, ZP0020, acrylonitrile content of 50%), add it to 450g of NMP (N-methylpyrrolidone) solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely transparent, to obtain a rubber solution with a solid content of 10%.

[0077] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 312.5g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 20%.

[0078] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into water under high-speed stirring at 3000 r / min to obtain aramid rubber precipitate.

[0079] S4. Granulation: The obtained precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber composite masterbatch.

[0080] (2) Preparation of a rubber composite material, the specific preparation process is as follows: Similar to Example 1, except that the aramid-rubber in-situ composite masterbatch was replaced with the aramid-rubber composite masterbatch prepared in Comparative Example 5.

[0081] Comparative Example 6: Preparation of aramid-rubber composite masterbatch and rubber composite material.

[0082] The aramid-rubber composite masterbatch was prepared using the same method as in Example 1, except that the volume ratio of water to ethanol in the coagulation bath used in step S3 of Comparative Example 6 was 1:40 (i.e., the proportion of ethanol was increased). Other process conditions were the same as in Example 1. The specific preparation process is as follows.

[0083] (1) A method for preparing an aramid-rubber composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Ruwen Company, ZP0020, acrylonitrile content of 50%), add it to 450g of NMP (N-methylpyrrolidone) solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely transparent, to obtain a rubber solution with a solid content of 10%.

[0084] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 312.5g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 20%.

[0085] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:40) under high-speed stirring at 3000 r / min to obtain aramid rubber precipitate.

[0086] S4. Granulation: The obtained precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber composite masterbatch.

[0087] (2) Preparation of a rubber composite material, the specific preparation process is as follows: Similar to Example 1, except that the aramid-rubber in-situ composite masterbatch was replaced with the aramid-rubber composite masterbatch prepared in Comparative Example 6.

[0088] Comparative Example 7: Preparation of aramid-rubber composite masterbatch and rubber composite material.

[0089] The aramid-rubber composite masterbatch was prepared using the same method as in Example 1, except that the stirring speed in step S3 of Comparative Example 7 was 500 r / min (lower than the stirring speed specified in this invention), and other process conditions were the same as in Example 1. The specific preparation process is as follows.

[0090] (1) A method for preparing an aramid-rubber composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Ruwen Company, ZP0020, acrylonitrile content of 50%), add it to 450g of NMP (N-methylpyrrolidone) solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely transparent, to obtain a rubber solution with a solid content of 10%.

[0091] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 312.5g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 20%.

[0092] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:20) under high-speed stirring at 500 r / min to obtain aramid rubber precipitate.

[0093] S4. Granulation: The obtained precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber composite masterbatch.

[0094] (2) Preparation of a rubber composite material, the specific preparation process is as follows: Similar to Example 1, except that the aramid-rubber in-situ composite masterbatch was replaced with the aramid-rubber composite masterbatch prepared in Comparative Example 7.

[0095] Comparative Example 8: Preparation of aramid-rubber composite masterbatch and rubber composite material.

[0096] The aramid-rubber composite masterbatch was prepared using the same method as in Example 1, except that the solid content of the rubber solution in step S1 of Comparative Example 8 was 15% (higher than the solid content limited by the present invention), and the other process conditions were the same as in Example 1. The specific preparation process is as follows.

[0097] (1) A method for preparing an aramid-rubber composite masterbatch, the specific steps of which are as follows: S1. Preparation of rubber solution: Weigh 50g of hydrogenated nitrile butadiene rubber (HNBR, Ruwen Company, ZP0020, acrylonitrile content of 50%), add it to 450g of NMP (N-methylpyrrolidone) solvent, and dissolve it at 120℃ with a stirring speed of 400r / min until it is completely transparent, to obtain a rubber solution with a solid content of 15%.

[0098] Preparation of S2, aramid rubber blend solution: Pour the rubber solution prepared in step S1 into a reaction vessel, and slowly add 312.5g of aramid precipitated fiber polymerization stock solution (self-made, para-aramid solid content of 4%) while stirring. After the addition is complete, continue stirring at 400r / min for 60min to mix the two solutions evenly, and obtain an aramid rubber blend solution with an aramid content (based on the total weight of the aramid precipitated fiber polymer as a percentage of the rubber raw material and the aramid precipitated fiber polymer, the same below) of 20%.

[0099] S3, coprecipitation: The aramid rubber blend solution from step S2 was slowly injected into a coagulation bath composed of water / ethanol (volume ratio 1:20) under high-speed stirring at 3000 r / min to obtain aramid rubber precipitate.

[0100] S4. Granulation: The obtained precipitate was washed, dried, and extruded and granulated in sequence to obtain aramid-rubber composite masterbatch.

[0101] (2) Preparation of a rubber composite material, the specific preparation process is as follows: Similar to Example 1, except that the aramid-rubber in-situ composite masterbatch was replaced with the aramid-rubber composite masterbatch prepared in Comparative Example 8.

[0102] Comparative Example 9: Preparation of aramid-rubber composite masterbatch and rubber composite material.

[0103] Comparative Example 9 uses finished aramid pulp as a raw material to replace the aramid precipitated fiber polymerization solution to prepare aramid-rubber composite masterbatch. The rubber raw material used is the same as in Example 1. The specific preparation process is as follows: (1) Pre-dispersion: Weigh 100g of aramid pulp, 395g of paraffin oil and 5g of dispersant (zinc stearate) and put them into a high-speed mixer. Stir at 2500rpm for 15 minutes at 30℃ to obtain a pre-dispersion. (2) Internal mixing: Weigh 2000g of HNBR rubber by weight, put HNBR into the internal mixer and preheat it to 130°C, add the pre-dispersion obtained in step (1), and internally mix at 150°C for 8 minutes. Discharge the material to obtain the internally mixed rubber. (3) Extrusion granulation: The intensive rubber is extruded at 160°C using a twin-screw extruder, air-cooled, granulated and packaged to obtain aramid pulp predispersed masterbatch, in which aramid pulp accounts for 20 wt% of the total mass of the masterbatch.

[0104] (4) Mixing: 200g of HNBR rubber (the same rubber raw material used in step S1 of this embodiment), 100g of carbon black, and 20g of aramid pulp pre-dispersion masterbatch prepared in this comparative example. The above components were mixed in an internal mixer, with the temperature controlled not to exceed 80℃; then 10g of ZnO, 2g of stearic acid, and 10g of plasticizer TOTM were added, and the mixture was continued to be mixed evenly to obtain the mixed rubber. The mixed rubber was taken out and placed to cool to 30℃; then it was milled on a two-roll mill, with 16g of BIPB-40 and 4g of TAIC-70 added, and the milling temperature controlled not to exceed 50℃, so that the vulcanizing agent and the mixed rubber were mixed evenly to form sheets. After sheeting, the rubber composite material was hot-pressed at 170℃ and 5MPa using an 80-ton flat vulcanizing machine.

[0105] Blank Example 1: Preparation of rubber composite material.

[0106] Rubber composite materials were prepared using the same method as in Example 1, except that no aramid-rubber in-situ composite masterbatch was added in this blank example 1. The specific preparation process is as follows: Compound formulation: 200g HNBR rubber (same as the rubber raw material used in step S1 of Example 1), 100g carbon black. The above components were mixed in a Banbury mixer, with the temperature controlled not to exceed 80℃; then 10g ZnO, 2g stearic acid, and 10g plasticizer TOTM were added, and mixing continued until homogeneous to obtain the mixed rubber. The mixed rubber was removed and allowed to cool to 30℃; then it was milled on a two-roll mill, with 16g BIPB-40 and 4g TAIC-70 added, controlling the milling temperature not to exceed 50℃, to ensure the vulcanizing agent and the mixed rubber were uniformly mixed into sheets. After sheeting, it was hot-pressed using an 80-ton flat vulcanizing press at 170℃ and 5 MPa to obtain the rubber composite material.

[0107] Blank Example 2: Preparation of rubber composite materials.

[0108] Rubber composite materials were prepared using the same method as in Example 2, except that no aramid-rubber in-situ composite masterbatch was added in this blank example 2. The specific preparation process is as follows: Compound formulation: 200g NBR rubber (same as the rubber raw material used in step S1 of Example 2), 100g carbon black. The above components were mixed in a Banbury mixer, with the temperature controlled not to exceed 80°C; then 10g ZnO, 2g stearic acid, and 10g plasticizer TOTM were added, and mixing continued until homogeneous to obtain the mixed rubber. The mixed rubber was removed and allowed to cool to 30°C; then it was milled on a two-roll mill, with 6g BIPB-40 and 4g TAIC-70 added, controlling the milling temperature not to exceed 50°C, to ensure the vulcanizing agent and the mixed rubber were uniformly mixed into sheets. After sheeting, it was hot-pressed using an 80-ton flat vulcanizing press at 170°C and 5 MPa to obtain the rubber composite material.

[0109] The performance test results of the rubber composite materials obtained in the above embodiments and comparative examples are shown in Table 1 below. The test methods involved are as follows: (1) Hardness test: The hardness of the rubber composite material was tested in accordance with GB / T 531.1-2008; (2) Tensile property test: The tensile strength of rubber composite material shall be tested in accordance with GB / T 528-2009; the elongation at break shall be tested in accordance with GB / T 528-2009; the stress at 100% constant elongation shall be tested in accordance with GB / T 528-2009. (3) Tear performance test: The tear strength of the rubber composite material was tested in accordance with GB / T 529-2008.

[0110] Table 1 Performance Test Results

[0111] From the experimental phenomena of the above examples and comparative examples, and the data in Table 1, it can be seen that: Examples 1-4, prepared using the method described in this invention, involve in-situ liquid-phase mixing of the aramid precipitate fiber polymerization solution and the rubber solution. High-speed stirring in the precipitate solution causes the para-aramid fibers to orient and form the aramid-rubber composite masterbatch. This method is simple to prepare, reduces fiber agglomeration and entanglement, and improves the dispersibility of aramid in rubber. When applied to rubber composite materials, the aramid-rubber in-situ composite masterbatch can yield rubber composite materials with superior mechanical properties. Figure 1 The image shown is an electron microscope image of the rubber composite material prepared in Example 1. Figure 1 It can be seen that the aramid fibers are evenly dispersed in the rubber matrix with less agglomeration and entanglement. The rubber has excellent encapsulation properties for the aramid fibers, and the aramid fibers are relatively long, thus having a good reinforcing effect.

[0112] It should be noted that when comparing performance results between different experiments, comparisons can be made between the same rubber raw material systems, but horizontal comparisons cannot be made between different rubber raw material systems.

[0113] The comparison of results between Example 1 and Blank Example 1, and between Example 2 and Blank Example 2, shows that under the same rubber formulation and mixing process conditions, the mechanical properties of the composite material are significantly improved after adding the aramid-rubber in-situ composite masterbatch prepared according to this invention. This invention achieves uniform fiber dispersion and strong interfacial bonding by liquid-phase blending and co-precipitation of the aramid precipitation solution and the rubber solution, allowing the aramid to form fibers in situ within the rubber matrix and be simultaneously encapsulated by the rubber. This results in better reinforcing performance of the aramid. The blank example did not contain any aramid component; its mechanical properties originated solely from the rubber / carbon black system itself. Therefore, the comparative results verify the effective reinforcing function of the aramid fibers in the in-situ composite masterbatch of this invention on the rubber matrix.

[0114] Comparisons of the results from Comparative Example 1 and Example 2, and Comparisons of the results from Comparative Example 2 and Example 1, show that when industrial xylene or acetone is used as the organic solvent to replace NMP, the aramid fiber polymerization solution precipitates during mixing with the rubber solution, failing to form a stable aramid-rubber blend solution. Subsequent co-precipitation and granulation operations cannot proceed. The fundamental reason is that the aramid molecular chains in the aramid precipitation solution maintain their dissolved state through strong polar interactions with NMP solvent molecules. When solvents such as xylene or acetone, which have significantly different polarities and mismatched solubility parameters with NMP, are used, the change in the solvent environment disrupts the solvation layer of the aramid molecular chains, causing the hydrogen bonds between the aramid molecular chains to reassociate and precipitate instantaneously.

[0115] Comparisons of the results from Comparative Example 3 and Example 2, and Comparative Example 4 and Example 1, show that when the acrylonitrile content in the rubber raw material is below 40%, even when NMP is used as a solvent, aramid fiber polymerization solution will still precipitate when mixed with the rubber solution, making subsequent operations impossible. This is because the acrylonitrile content determines the polarity of the rubber molecules. When the acrylonitrile content is ≥40% in high-polarity NBR / HNBR, the abundant cyano groups (-CN) on its molecular chains can form a fully compatible molecular-level entanglement network with the high-polarity aramid molecular chains in the NMP system through dipole-dipole interactions. When the acrylonitrile content is too low, the polarity of the rubber molecular chains is significantly reduced, resulting in repulsion and desolvation effects on the aramid molecular chains in NMP, disrupting the dissolution state of the aramid, and ultimately affecting the preparation of the composite masterbatch.

[0116] A comparison of the results from Comparative Example 5 and Example 1 shows that when the coagulation bath is replaced with pure water, although co-precipitation and granulation can be completed, the reinforcing effect of the resulting masterbatch is significantly reduced. Pure water is a strong non-solvent for aramid; after the blending solution is injected with pure water, the aramid precipitation rate is too fast, and the aramid molecular chains are precipitated before they are fully oriented, failing to form microfibers with high aspect ratio and regular structure. At the same time, the rubber also precipitates rapidly due to strong coagulation. The two cannot be synchronized in time, and the rubber cannot be deposited and coated on the surface of the newly formed fibers in time, resulting in the separate precipitation of fibers and rubber matrix and weakened interfacial bonding. This invention uses a coagulation bath with a suitable water / ethanol ratio. The addition of ethanol reduces the polarity of the coagulation bath, slows down the precipitation rate of aramid, and provides sufficient time for the aramid molecular chains to be fully oriented under high shear and for the rubber to be simultaneously precipitated and coated, achieving the synchronous occurrence of fiber formation and coating processes, and finally obtaining an aramid-rubber in-situ composite masterbatch with excellent application performance.

[0117] A comparison of the results from Comparative Example 6 and Example 1 shows that an excessively high ethanol ratio reduces the coagulation capacity of the coagulation bath, resulting in insufficient driving force for aramid precipitation. Some aramid molecules cannot effectively escape the solvent environment and are unable to fully precipitate, remaining suspended in the coagulation bath and failing to settle, leading to a decrease in yield. Simultaneously, the precipitated fibers are too thin and weak due to the slow precipitation rate, making them prone to breakage and damage during subsequent washing and drying processes, and difficult to maintain a complete microfiber reinforcement morphology. Therefore, it can be seen that using a suitable ratio of water and ethanol in the coagulation bath is more conducive to obtaining aramid-rubber in-situ composite masterbatch with excellent comprehensive application performance.

[0118] A comparison of the results from Comparative Example 7 and Example 1 shows that the reinforcing effect of the masterbatch decreases significantly when the stirring speed of the co-precipitation process is reduced. This is because the blend solution contains a large amount of high-viscosity rubber components, and the aramid molecular chains experience viscous resistance during precipitation. Sufficiently high shear stress can force the aramid molecular chains to extend, orient, and crystallize along the shear direction. When the stirring rate is insufficient, the aramid molecular chains cannot orient themselves at the moment of precipitation and can only precipitate as amorphous powder or short rods, rather than forming fibers with a high aspect ratio, ultimately affecting the reinforcing effect of the masterbatch in the rubber composite material.

[0119] A comparison of the results from Comparative Example 8 and Example 1 shows that when the solid content of the rubber solution is high, the viscosity of the blend solution increases. After the aramid precipitate is added, it is difficult for the aramid molecular chains to diffuse uniformly at the molecular level, and the aramid and rubber molecular chains cannot form sufficient molecular entanglement in the liquid phase. This results in uneven distribution of the precipitated fibers in the rubber matrix, with fibers clustered in some areas and sparse in others. Simultaneously, the interfacial bonding quality decreases due to insufficient contact between the two phases, ultimately affecting the reinforcing effect of the masterbatch in the rubber composite material.

[0120] A comparison of the results from Comparative Example 9 and Example 1 shows that when finished aramid pulp is used instead of the aramid precipitated fiber polymerization solution, the resulting masterbatch, while exhibiting some reinforcing effect, is significantly weaker than that of Example 1. This is because the finished aramid pulp is fiber formed through spinning, cutting, and other processes, resulting in strong agglomerates between the fibers due to intense hydrogen bonding. Even under the high shear conditions of this invention, these agglomerates cannot be completely broken down to the single fiber level, existing as residual agglomerates in the masterbatch, becoming stress concentration points and potential defects in the composite material. In contrast, this invention uses the aramid precipitated solution, where the aramid enters the masterbatch preparation system in the form of molecular chains. Hydrogen bonds between the fibers have not yet formed, therefore, no agglomerates need to be broken down during the co-precipitation process. Fibers are directly generated through molecular chain orientation crystallization, eliminating the possibility of agglomeration at the source. Ultimately, an aramid-rubber in-situ composite masterbatch with superior reinforcing effect is obtained, improving the overall performance of the rubber composite material.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing an aramid-rubber in-situ composite masterbatch, characterized in that, The preparation method is as follows: S1. Dissolve the rubber raw material in an organic solvent to obtain a rubber solution; S2. The rubber solution is mixed with the aramid precipitated fiber polymerization solution in the liquid phase to obtain an aramid rubber blend solution; S3. The aramid rubber blend solution is injected into a coagulation bath under high-speed stirring to co-precipitate, so that the aramid crystallizes into fibers in situ and settles synchronously with the rubber to obtain aramid rubber precipitate. S4. The precipitate is washed, dried and granulated to obtain aramid-rubber in-situ composite masterbatch.

2. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 1, characterized in that, The organic solvent mentioned in step S1 is the same as the solvent system of the aramid precipitated fiber polymerization solution.

3. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 2, characterized in that, The organic solvent is N-methylpyrrolidone.

4. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 1, characterized in that, The rubber raw material is nitrile rubber and / or hydrogenated nitrile rubber, and the acrylonitrile content in the rubber raw material is ≥40%.

5. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 1, characterized in that, The solid content of the rubber solution in step S1 is 5%-10%; The solid content of the aramid precipitated fiber polymerization solution in step S2 is 3-5%.

6. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 1, characterized in that, The dissolution temperature in step S1 is 80-130℃, and the stirring speed is 300-500 r / min; The stirring speed for liquid phase mixing in step S2 is 400-600 r / min, and the stirring time is 30-60 min.

7. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 1, characterized in that, In the aramid rubber blend solution, the aramid precipitated fiber polymer accounts for 10%-30% of the total weight of the rubber raw material and the aramid precipitated fiber polymer.

8. The method for preparing an aramid-rubber in-situ composite masterbatch according to claim 1, characterized in that, The high-speed stirring speed mentioned in step S3 is 1000-3000 r / min; The coagulation bath comprises water and ethanol, with a volume ratio of water to ethanol of 1:(15-25).

9. An aramid-rubber in-situ composite masterbatch, characterized in that, The aramid-rubber in-situ composite masterbatch is prepared by the preparation method described in any one of claims 1-8.

10. An application of the aramid-rubber in-situ composite masterbatch according to claim 9, characterized in that, The aramid-rubber in-situ composite masterbatch is used in rubber composite materials.

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