Preparation method of aramid pulp
By employing ultrasonic-assisted pretreatment, gradient mechanical grinding, hydraulic classification, and chemical enzymatic hydrolysis, the problems of high energy consumption, uneven fiber distribution, insufficient surface activity, and significant safety hazards in aramid pulp production have been solved, enabling the preparation of raw materials for high-performance composite materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies in aramid pulp production suffer from problems such as low energy utilization, uneven fiber length, shallow fibrillation, lack of surface active sites, serious side reactions, and harsh production environment, which limit the improvement of product performance and pose significant safety hazards.
The method employs ultrasonic-assisted pretreatment, gradient mechanical grinding and hydraulic classification, chemical-assisted fibrillation reinforcement and low-temperature drying. Fiber length and surface properties are controlled through surfactant pretreatment, enzymatic hydrolysis and hydraulic classification, combined with low-temperature airflow drying and negative pressure packaging to form a uniform microfibril structure.
It improves the specific surface area, fiber length uniformity, and surface active sites of aramid pulp, reduces energy consumption and production costs, and enhances the performance and safety of composite materials, which is in line with the industrial policy of sustainable development.
Smart Images
Figure BDA0005744334870000091 
Figure BDA0005744334870000101
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-performance fiber material processing technology, specifically to a method for preparing aramid pulp. Background Technology
[0002] Aramid pulp, as a unique "microfibrillated" form of aramid product, possesses an extremely high specific surface area and abundant surface end groups. When used as a reinforcing phase, it can form strong physical anchoring and chemical bonding with matrix materials (such as rubber, resin, and plastics), thereby endowing composite materials with excellent mechanical properties, heat resistance, and wear resistance. It plays an irreplaceable role in fields such as high-performance tires, brake pads, and aerospace composite materials.
[0003] Currently, the large-scale industrial production of aramid pulp almost entirely relies on high-energy mechanical grinding. The basic process is as follows: aramid filaments are opened and cut into short fibers (usually 3-6mm), and then the short fibers are passed through a multi-stage series of disc mills, colloid mills, and other equipment in an aqueous medium. The strong shearing force between the moving and stationary grinding discs forces the fibers to split and break along the axial direction, ultimately forming a fibrillated "feather-like" structure.
[0004] Although this technological approach is mature, a thorough analysis of its technological bottlenecks reveals that its shortcomings are systemic, severely restricting further improvements in product performance and industrial upgrading.
[0005] Low energy efficiency and poor economic performance:
[0006] Mechanism analysis: Aramid molecules are highly oriented, highly crystalline, and have strong interchain forces, making them typical difficult-to-break materials. Direct grinding in dry or low-moisture systems results in most of the energy being converted into heat and sound energy, with only a very small portion used for fiber breakage and new surface formation.
[0007] Consequences: The equipment has extremely high energy consumption (typically >18kWh / kg), the grinding disc wears out quickly, and the equipment investment and operation and maintenance costs are high, making it a major component of pulp production costs.
[0008] Uncontrolled fiber length and uneven microstructure:
[0009] Mechanism analysis: Mechanical shearing is a typical stochastic process in which the magnitude and direction of the force are uncontrollable. This results in fiber breakage that is "violent" and disordered, producing fragments ranging in size from nanometers to millimeters, with an extremely wide length distribution (spanning more than 1 mm).
[0010] Consequences: ① Fibers that are too short (<0.5μm): mainly serve a filling function, unable to form an effective three-dimensional reinforcing network, and may instead become stress concentration points. ② Fibers that are too long (>2mm): poor dispersibility, easily forming "fiber bundles" or "fiber clusters" in the matrix, not only failing to provide uniform reinforcement but also becoming sources of defects in the product, seriously affecting the mechanical properties and appearance quality of the composite material. ③ Poor batch stability, making it difficult to accurately control product quality.
[0011] The degree of fibrillation is shallow, and the surface active sites are scarce.
[0012] Mechanism analysis: Pure physical shearing can only disrupt the transverse bonds between fibers and some longitudinal weak points, but its effect is limited for highly crystalline fiber bodies. It mainly produces macroscopic "splitting" rather than molecular-level "untangling".
[0013] Consequences: The generated "feathers" are mostly large fibrils composed of a few interconnected fibrils, with very few true microfibrils (diameter <100nm). This results in a fiber specific surface area far lower than the theoretical value (typically <11m²). 2 The number of reactive groups such as amino and carbonyl groups on the surface is insufficient, resulting in weak interfacial adhesion with the matrix and limiting the improvement of composite material performance.
[0014] Severe side effects damage the intrinsic properties of the fiber:
[0015] Mechanism analysis: The intense friction during the grinding process can cause the local temperature of the fiber to rise instantly to several hundred degrees Celsius. Although aramid has a certain degree of thermal stability, under these extreme non-equilibrium thermodynamic conditions, molecular chain breakage (thermal degradation) and oxidation will still occur, leading to a decrease in the fiber molecular weight.
[0016] Consequences: The mechanical properties of the pulp itself (such as strength and modulus) are impaired, and the performance limits of composite materials reinforced with it are restricted by the inherent deficiencies of the pulp. Furthermore, high temperatures may cause yellowing of the fibers, affecting the product's color.
[0017] The production environment is harsh and poses significant safety hazards.
[0018] Mechanism analysis: The high insulation properties of aramid fibers and the high specific surface area generated during grinding make them highly susceptible to static electricity. Dry fiber powder forms dust clouds in high-speed airflow.
[0019] Consequences: Not only does it pollute the environment and harm workers' respiratory health, but it also poses a safety risk of dust explosion.
[0020] Therefore, we propose a method for preparing aramid pulp. Summary of the Invention
[0021] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing aramid pulp, comprising the following steps:
[0022] S1: Pretreatment and pre-impregnation: Aramid short-cut fibers are placed in a mixed solution containing specific auxiliaries and subjected to ultrasonic-assisted treatment, followed by solid-liquid separation and washing to obtain pretreated wet fibers;
[0023] S2: Gradient mechanical grinding and hydraulic classification: The pretreated wet fibers are mixed with water to form a suspension, and then subjected to first-stage coarse grinding, second-stage medium grinding and third-stage fine grinding in sequence. After each stage of grinding, hydraulic classification is used to collect only the fiber slurry within a predetermined length range to enter the next stage of grinding.
[0024] S3: Chemically Assisted Reinforced Fibrillation: The slurry after three-stage fine grinding is introduced into a reaction vessel and subjected to controlled enzymatic hydrolysis under specific temperature, pH and catalyst conditions to further promote fiber fibrillation and detangling.
[0025] S4: Dehydration, drying and opening: The slurry after enzymatic hydrolysis is dehydrated by pressure filtration. The resulting wet pulp cake is crushed and dried by low-temperature airflow. Then it is opened by an airflow screenless opening machine. Finally, it is vacuum packaged under negative pressure to obtain the finished aramid pulp.
[0026] Preferably, in step S1, the length of the aramid chopped fibers is 5-10 mm; the specific auxiliary agent is a composition comprising a nonionic surfactant and a weakly polar organic solvent, wherein the nonionic surfactant is selected from fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether, and the weakly polar organic solvent is selected from N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO); the total concentration of the auxiliary agent in the mixed solution is 0.5-2 wt%.
[0027] Preferably, the nonionic surfactant is fatty alcohol polyoxyethylene ether AEO-9, the weakly polar organic solvent is DMF, and the total concentration of the additives is 1.0 to 1.5 wt%.
[0028] Preferably, in step S1, the frequency of the ultrasound-assisted treatment is 20–40 kHz, the power is 500–1000 W, and the treatment time is 10–30 minutes.
[0029] Preferably, in step S2, the solid content of the suspension is 1.0 to 1.5 wt%; the goal of the first-stage coarse grinding is to control the fiber length to 2.5 to 3.5 mm; the goal of the second-stage medium grinding is to control the fiber length to 1.2 to 2.0 mm; and the goal of the third-stage fine grinding is to control the fiber length to 0.7 to 1.2 mm.
[0030] Preferably, in step S2, the hydraulic classification is achieved using vibrating screens or hydrocyclones with different mesh sizes to ensure that the fiber length distribution concentration entering the next stage of grinding is ≥85%.
[0031] Preferably, in step S3, the enzyme used in the controllable enzymatic hydrolysis is a complex enzyme system of cellulase and laccase, wherein the mass ratio of cellulase to laccase is (3-5):1.
[0032] Preferably, the enzymatic hydrolysis reaction has a pH of 4.5–5.5, a temperature of 45–55°C, a reaction time of 60–120 minutes, and the catalyst is a metal chloride, the amount of which is 0.01–0.05 wt% of the dry weight of the slurry.
[0033] Preferably, in step S4, the temperature of the low-temperature airflow drying is 100–120°C, and the moisture content of the dried material is 6–8 wt%.
[0034] Preferably, the order of steps S2 and S3 cannot be reversed, and the chemically assisted strengthening fibrillation treatment must be performed after gradient mechanical milling.
[0035] Compared with the prior art, the present invention provides a method for preparing aramid pulp, which has the following beneficial effects:
[0036] 1. In the preparation method of this aramid pulp, the enzyme does not directly "digest" the aramid backbone (because it has no effect on aramid), but rather achieves a gentle dissociation "from the surface inward" by attacking the amorphous regions, terminal groups, and non-covalent bond networks such as hydrogen bonds between fibers on the fiber surface. Experiments have shown that the specific surface area of the product of this invention can reach 6.5–8.0 m². 2 / g, which is much higher than the 4.0–5.5m of traditional methods. 2 / g. When applied to styrene-butadiene rubber (SBR), the tensile strength of the vulcanizate can be increased from the traditional 23MPa to over 28MPa, and the abrasion resistance is improved by more than 25%. This is because more microfibrils and active sites mean stronger physical interlocking and chemical bonding.
[0037] 2. The preparation method of this aramid pulp, consisting of "gradient grinding + hydraulic classification," constitutes a dynamic, closed-loop length screening system. Each grinding stage acts like a precise "molecular scissors," processing only excessively long fibers, while hydraulic classification acts like a strict "quality inspector," rejecting substandard products for reprocessing. This mechanism ensures that the final product has highly uniform fiber length (length distribution span can be controlled within 0.6 mm, concentration ≥ 85%). Microscopically, uniformly long fibers can form a more regular and dense reinforcing network in the matrix, avoiding stress concentration, achieving a dispersion rating of A+, and completely eliminating agglomeration.
[0038] 3. The preparation method of this aramid pulp employs a "divide and conquer" strategy with chemical pre-impregnation. Surfactants and solvents pre-construct a lubricating and swelling layer on the fiber surface, effectively "softening" the fiber and significantly reducing resistance to subsequent physical shearing. Simultaneously, dry grinding and high temperatures are avoided. The overall effect is a reduction of over 30% in unit energy consumption throughout the preparation process, from the traditional >18 kWh / kg to 12–14 kWh / kg, while also extending equipment life and significantly lowering overall production costs.
[0039] 4. The preparation method of this aramid pulp effectively avoids localized high temperatures in the core process steps because the grinding is carried out in water and the enzymatic hydrolysis is also completed in a mild aqueous solution environment. By comparing the molecular weight (GPC test) and strength (single fiber strength test) of the fibers before and after enzymatic hydrolysis, it was found that the pulp prepared by this invention has a molecular weight retention rate and single fiber strength retention rate of >98%, far superior to traditional methods (usually <92%). This provides the most fundamental raw material guarantee for manufacturing top-performance composite materials.
[0040] 5. In the preparation method of this aramid pulp, the surfactant in the pre-impregnation step effectively dissipates static electricity from the fibers, suppressing dust generation at the source. The fully enclosed water-based process and the final negative pressure packaging ensure that the dust concentration at the production site is far below national safety standards. The enzymatic hydrolysis process itself is also a green biocatalytic process, with mild conditions and no harmful byproduct emissions, conforming to sustainable development industrial policies. Detailed Implementation
[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0042] Example
[0043] An Example of a Method for Preparing Aramid Pulp
[0044] A method for preparing aramid pulp includes the following steps:
[0045] S1: Pretreatment and pre-impregnation: Aramid short-cut fibers are placed in a mixed solution containing specific auxiliaries and subjected to ultrasonic-assisted treatment, followed by solid-liquid separation and washing to obtain pretreated wet fibers;
[0046] S2: Gradient mechanical grinding and hydraulic classification: The pretreated wet fibers are mixed with water to form a suspension, and then subjected to first-stage coarse grinding, second-stage medium grinding and third-stage fine grinding in sequence. After each stage of grinding, hydraulic classification is used to collect only the fiber slurry within a predetermined length range to enter the next stage of grinding.
[0047] S3: Chemically Assisted Reinforced Fibrillation: The slurry after three-stage fine grinding is introduced into a reaction vessel and subjected to controlled enzymatic hydrolysis under specific temperature, pH and catalyst conditions to further promote fiber fibrillation and detangling.
[0048] S4: Dehydration, drying and opening: The slurry after enzymatic hydrolysis is dehydrated by pressure filtration. The resulting wet pulp cake is crushed and dried by low-temperature airflow. Then it is opened by an airflow screenless opening machine. Finally, it is vacuum packaged under negative pressure to obtain the finished aramid pulp.
[0049] Specifically, in step S1, the length of the aramid chopped fibers is 5-10 mm; the specific auxiliary agent is a composition comprising a nonionic surfactant and a weakly polar organic solvent, wherein the nonionic surfactant is selected from fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether, and the weakly polar organic solvent is selected from N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO); the total concentration of the auxiliary agent in the mixed solution is 0.5-2 wt%.
[0050] Specifically, the nonionic surfactant is fatty alcohol polyoxyethylene ether AEO-9, the weakly polar organic solvent is DMF, and the total concentration of the additives is 1.0 to 1.5 wt%.
[0051] Specifically, in step S1, the frequency of the ultrasound-assisted treatment is 20–40 kHz, the power is 500–1000 W, and the treatment time is 10–30 minutes.
[0052] Specifically, in step S2, the solid content of the suspension is 1.0 to 1.5 wt%; the goal of the first-stage coarse grinding is to control the fiber length to 2.5 to 3.5 mm; the goal of the second-stage medium grinding is to control the fiber length to 1.2 to 2.0 mm; and the goal of the third-stage fine grinding is to control the fiber length to 0.7 to 1.2 mm.
[0053] Specifically, in step S2, hydraulic classification is achieved using vibrating screens or hydrocyclones with different mesh sizes to ensure that the fiber length distribution concentration entering the next stage of grinding is ≥85%.
[0054] Specifically, in step S3, the enzyme used in the controllable enzymatic hydrolysis is a complex enzyme system of cellulase and laccase, wherein the mass ratio of cellulase to laccase is (3-5):1.
[0055] Specifically, the pH value of the enzymatic hydrolysis reaction is 4.5–5.5, the temperature is 45–55℃, the reaction time is 60–120 minutes, and the catalyst is a metal chloride, the amount of which is 0.01–0.05 wt% of the dry weight of the slurry.
[0056] Specifically, in step S4, the temperature of the low-temperature airflow drying is 100–120°C, and the moisture content of the dried material is 6–8 wt%.
[0057] Specifically, the order of steps S2 and S3 cannot be reversed, and the chemically assisted strengthening fibrillation treatment must be performed after gradient mechanical milling.
[0058] Through the above technical solution, in this invention, the enzyme does not directly "digest" the aramid backbone (because it has no effect on aramid), but rather achieves a gentle dissociation "from the surface inward" by attacking the amorphous regions, terminal groups, and non-covalent bond networks such as hydrogen bonds on the fiber surface. Experiments have shown that the specific surface area of the product of this invention can reach 6.5–8.0 m². 2 / g, which is much higher than the 4.0–5.5m of traditional methods. 2 / g. When applied to styrene-butadiene rubber (SBR), the tensile strength of the vulcanizate can be increased from the traditional 23MPa to over 28MPa, and the abrasion resistance is improved by more than 25%. This is because more microfibrils and active sites mean stronger physical interlocking and chemical bonding. "Gradient grinding + hydraulic classification" constitutes a dynamic, closed-loop length screening system. Each grinding stage is like a precise "molecular scissors," processing only excessively long fibers, while hydraulic classification is like a strict "quality inspector," rejecting unqualified products for reprocessing. This mechanism ensures that the fiber length of the final product is highly uniform (the length distribution span can be controlled within 0.6mm, and the concentration is ≥85%). Microscopically, uniformly long fibers can form a more regular and dense reinforcing network in the matrix, avoiding stress concentration, achieving a dispersion rating of A+, and completely eliminating agglomeration. Chemical preimpregnation is a "divide and conquer" strategy. Surfactants and solvents pre-construct a lubricating and swelling layer on the fiber surface, effectively "softening" the fiber and significantly reducing resistance to subsequent physical shearing. Simultaneously, dry grinding and high temperatures are avoided. The overall effect is a reduction of over 30% in unit energy consumption throughout the preparation process, from the traditional >18 kWh / kg to 12-14 kWh / kg. Equipment lifespan is extended, and overall production costs are significantly reduced. Since grinding is carried out in water, and enzymatic hydrolysis is also completed in a mild aqueous environment, the entire core process effectively avoids the generation of localized high temperatures. A comparison of the molecular weight (GPC test) and strength (single fiber strength test) of the fibers before and after enzymatic hydrolysis reveals that the pulp prepared by this invention has a molecular weight retention rate (>98%) and single fiber strength retention rate, far superior to traditional methods (typically <92%). This provides the most fundamental raw material guarantee for manufacturing top-performance composite materials. The surfactants in the pre-impregnation step effectively dissipate static electricity from the fibers, suppressing dust generation at the source. The fully enclosed water-based process and final negative pressure packaging ensure that the dust concentration at the production site is far below national safety standards. Enzymatic hydrolysis is itself a green biocatalytic process, with mild conditions and no harmful byproduct emissions, which is in line with sustainable development industrial policies.
[0059] Example:
[0060] S1: Pretreatment and Pre-impregnation. Weigh 200g of 8mm long aramid 1313 chopped fibers and add them to a mixed solution containing 2L deionized water, 20g of fatty alcohol polyoxyethylene ether (AEO-9), and 30mL of N,N-dimethylformamide (DMF). Place the mixture in an ultrasonic cleaner, set the ultrasonic frequency to 28kHz, the power to 800W, and treat for 20 minutes. After treatment, rinse the fibers repeatedly with deionized water 3 times, and then centrifuge at 3000rpm for 10 minutes to obtain pretreated wet fibers.
[0061] S2: Gradient Mechanical Grinding. Pretreated wet fibers were mixed with deionized water to prepare a suspension with a solid content of 1.2 wt%. The suspension was pumped into a first-stage coarse grinding mill using a screw pump, with a target length of 3.0 mm. The ground slurry was immediately hydraulically classified through an 80-mesh vibrating screen. The material remaining on the screen (fibers approximately 3.0 mm in length) was collected and fed into a second-stage medium grinding mill, with a target length of 1.5 mm. It was then classified again through a 120-mesh vibrating screen, and the material remaining on the screen was collected and fed into a third-stage fine grinding mill, with a target length of 1.0 mm. Finally, the slurry was collected through a 150-mesh vibrating screen. Testing showed that the fiber length distribution concentration of this slurry reached 88%.
[0062] S3: Chemically Assisted Fibrillation Enhancement. The entire slurry after three-stage fine grinding was transferred to a 10L reactor. A compound enzyme preparation (10g cellulase and 2g laccase) and zinc chloride catalyst (0.04g, based on the dry weight of the slurry) were added. The pH of the slurry was adjusted to 5.0 using an acetic acid / sodium acetate buffer solution. Stirring was started and the temperature was raised to 50°C. The reaction was maintained at this temperature for 90 minutes. After the reaction was completed, the temperature was raised to 95°C and maintained for 10 minutes to inactivate the enzyme.
[0063] S4: Dehydration, Drying, and Opening. The enzyme-inactivated pulp is pumped into a plate and frame filter press for dehydration, yielding a wet pulp cake with a moisture content of approximately 70%. This cake is then crushed into small pieces using a hammer mill and subsequently sent to an airflow low-temperature dryer, where it is dried at 110°C to a moisture content of 7%. After drying, the block pulp is fully opened using an airflow screenless opening machine and then packaged in 1kg / bag quantities using a negative pressure vacuum packaging machine to obtain the finished aramid pulp.
[0064] Comparative Example 1
[0065] Using the user-provided original method: Aramid fabric blocks are broken into 10mm short fibers, then cut into 5mm short fibers using a fiber cutter. Without any chemical pretreatment, they are directly added to water and stirred to form a suspension (solid content approximately 1.6%). Then, they undergo three mechanical milling processes (target lengths controlled at 2.5-3mm, 1.5-2mm, and 0.7-1.2mm respectively), without intermediate grading. Afterwards, they are pressure filtered, dried (moisture content 7%), opened, and packaged. No enzymatic hydrolysis is performed.
[0066] Performance Testing and Comparative Analysis
[0067]
[0068]
[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing aramid pulp, characterized in that: Includes the following steps: S1: Pretreatment and pre-impregnation: Aramid short-cut fibers are placed in a mixed solution containing specific auxiliaries and subjected to ultrasonic-assisted treatment, followed by solid-liquid separation and washing to obtain pretreated wet fibers; S2: Gradient mechanical grinding and hydraulic classification: The pretreated wet fibers are mixed with water to form a suspension, and then subjected to first-stage coarse grinding, second-stage medium grinding and third-stage fine grinding in sequence. After each stage of grinding, hydraulic classification is used to collect only the fiber slurry within a predetermined length range to enter the next stage of grinding. S3: Chemically Assisted Reinforced Fibrillation: The slurry after three-stage fine grinding is introduced into a reaction vessel and subjected to controlled enzymatic hydrolysis under specific temperature, pH and catalyst conditions to further promote fiber fibrillation and detangling. S4: Dehydration, drying and opening: The slurry after enzymatic hydrolysis is dehydrated by pressure filtration. The resulting wet pulp cake is crushed and dried by low-temperature airflow. Then it is opened by an airflow screenless opening machine. Finally, it is vacuum packaged under negative pressure to obtain the finished aramid pulp.
2. The method for preparing aramid pulp according to claim 1, characterized in that: In step S1, the length of the aramid chopped fibers is 5-10 mm; the specific auxiliary agent is a composition comprising a nonionic surfactant and a weakly polar organic solvent, wherein the nonionic surfactant is selected from fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether, and the weakly polar organic solvent is selected from N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO); the total concentration of the auxiliary agent in the mixed solution is 0.5-2 wt%.
3. The method for preparing aramid pulp according to claim 2, characterized in that: The nonionic surfactant is fatty alcohol polyoxyethylene ether AEO-9, the weakly polar organic solvent is DMF, and the total concentration of the additives is 1.0 to 1.5 wt%.
4. The method for preparing aramid pulp according to claim 1, characterized in that: In step S1, the frequency of the ultrasound-assisted treatment is 20–40 kHz, the power is 500–1000 W, and the treatment time is 10–30 minutes.
5. The method for preparing aramid pulp according to claim 1, characterized in that: In step S2, the solid content of the suspension is 1.0 to 1.5 wt%; the goal of the first-stage coarse grinding is to control the fiber length to 2.5 to 3.5 mm; the goal of the second-stage medium grinding is to control the fiber length to 1.2 to 2.0 mm; and the goal of the third-stage fine grinding is to control the fiber length to 0.7 to 1.2 mm.
6. The method for preparing aramid pulp according to claim 1, characterized in that: In step S2, hydraulic classification is achieved using vibrating screens or hydrocyclones with different mesh sizes to ensure that the fiber length distribution concentration entering the next stage of grinding is ≥85%.
7. The method for preparing aramid pulp according to claim 1, characterized in that: In step S3, the enzyme used in the controllable enzymatic hydrolysis is a complex enzyme system of cellulase and laccase, wherein the mass ratio of cellulase to laccase is (3-5):
1.
8. The method for preparing aramid pulp according to claim 7, characterized in that: The enzymatic hydrolysis reaction is carried out at a pH of 4.5–5.5, a temperature of 45–55°C, and a reaction time of 60–120 minutes. The catalyst is a metal chloride, and its dosage is 0.01–0.05 wt% of the dry weight of the slurry.
9. The method for preparing aramid pulp according to claim 1, characterized in that: In step S4, the temperature of the low-temperature airflow drying is 100-120℃, and the moisture content of the dried material is 6-8 wt%.
10. The method for preparing aramid pulp according to claim 1, characterized in that: The order of steps S2 and S3 cannot be reversed, and the chemically assisted strengthening fibrillation treatment must be performed after gradient mechanical milling.