Method for continuously producing aramid pulp with high gripping force, aramid pulp with high gripping force and application of aramid pulp
By employing continuous production processes and grinding disc combination design, the problems of quality fluctuations and low efficiency in aramid pulp production have been solved, enabling stable production of aramid pulp with high adhesion. This is suitable for high-end friction materials such as brake pads, improving the adhesion and mechanical properties of the products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-13
AI Technical Summary
The intermittent production of existing aramid pulp results in large quality fluctuations, making it impossible to achieve high adhesion, and the traditional process is inefficient and cannot meet the needs of high-end materials.
By employing a continuous production process, a combination of wide-tooth and fine-tooth grinding discs is used in coarse and fine grinding stages. Combined with online fiber length detection and acoustic emission sensors, an optimized balance between fiber buffing rate and energy consumption is achieved. A graded control mechanism is constructed to ensure precise control of fiber length and specific surface area.
It enables continuous production of aramid pulp with high adhesion, improves production efficiency, reduces energy consumption, and enhances product quality stability. It is suitable for high-end friction materials such as brake pads, and enhances the adhesion and mechanical properties of brake pads.
Smart Images
Figure CN121653987A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fiber preparation technology, and more particularly to a method for continuous production of high-adhesion aramid pulp, as well as the application of high-adhesion aramid pulp. Background Technology
[0002] Aramid pulp is a composite material reinforcing fiber produced by surface microfibrillation of aramid fibers. Its surface exhibits a fluffy, ultrafine microfibrillary structure, possessing characteristics such as large specific surface area, high temperature resistance (long-term operating temperature up to 250℃), and corrosion resistance. In rubber composites, this material can increase tensile strength by 12%-28% and improve impact strength by 9%-22%, and is widely used in industrial fields such as wear-resistant layers for transmission belts and friction materials.
[0003] Existing aramid pulp production is mostly carried out in an intermittent manner. The mass fraction of aramid pulp needs to be adjusted at each stage, which affects production efficiency. Moreover, the product quality fluctuates greatly, and it is impossible to adjust the adhesion of the pulp. Summary of the Invention
[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for continuous production of high-adhesion aramid pulp, as well as the application of high-adhesion aramid pulp, which realizes continuous production from fiber filament to finished pulp, and the prepared aramid pulp has high adhesion.
[0005] To achieve the above objectives, the present invention provides a method for continuous production of high-adhesion aramid pulp, comprising:
[0006] The dispersion of aramid fiber chopped raw material was subjected to coarse grinding and fine grinding in sequence to obtain aramid pulp with high adhesion.
[0007] The coarse grinding uses wide-tooth grinding discs;
[0008] The fine grinding process uses fine-tooth grinding discs.
[0009] This invention addresses the segmented control requirements of a continuous refining system for aramid pulp. It achieves an optimized balance between fiber brooming rate and energy consumption through precise four-stage regulation. Furthermore, by designing and combining the tooth profiles of the grinding discs, it further enhances the specific surface area and adhesion of aramid pulp.
[0010] Figure 4 This is a process flow diagram of the continuous production of high-adhesion aramid pulp provided by the present invention.
[0011] This invention employs a continuous production process to replace the traditional intermittent single-tank pulping mode. This process solves the quality fluctuation problem caused by frequent start-ups and shutdowns in intermittent production through continuous control throughout the entire process: in traditional processes, there are prolonged power fluctuations during the equipment's advance and retreat of the grinding discs, and the effective production time within a single pulping cycle is low; while continuous production allows the pulping equipment to maintain a stable operating state, avoiding periodic power oscillations, effectively improving production efficiency, and simultaneously achieving standard deviation control of product performance parameters, providing process assurance for the large-scale production of high-end aramid pulp.
[0012] The method provided by this invention is applicable to general aramid fibers known to those skilled in the art, including but not limited to para-aramid fibers.
[0013] The length of the aramid fiber chopped raw material is preferably 6 to 12 mm, and for example, it can be 6, 8, 10, or 12 mm.
[0014] The concentration of the aramid fiber chopped raw material dispersion is preferably 4% to 7%, and for example, it can be 4%, 5%, 6%, 7%, or any of the above values as the upper or lower limit.
[0015] In the coarse grinding stage, wide-toothed grinding discs are used to efficiently cut the fibers, quickly achieving the set fiber length and improving production efficiency. Real-time feedback from an online fiber length detector prevents over-cutting. Simultaneously, the wide-toothed grinding discs can break up clusters of fibers, improving fiber dispersibility and specific surface area in water.
[0016] The tooth width of the wide-tooth grinding disc is preferably in the range of 4 to 6.5 mm. For example, it can be 4, 4.5, 5, 5.5, 6, or 6.5 mm, or any of the above values as the upper or lower limit.
[0017] The tooth height of the wide-tooth grinding disc is preferably in the range of 5 to 8 mm. For example, it can be 5, 6, 7, or 8 mm, or any of the above values can be the upper or lower limit.
[0018] The tooth pitch range of the wide-tooth grinding disc is preferably 8 to 16 mm. For example, it can be 8, 9, 10, 11, 12, 13, 14, 15, or 16 mm, or any of the above values as the upper or lower limit.
[0019] In the real-time fissification determination stage, an acoustic emission sensor is used to analyze the high-frequency acoustic signals generated by fissile fibers to determine the fissification rate in real time, thus deciding whether the fiber can enter the fine grinding stage. In practical applications, this determination system reduces the fissification rate detection response time to 8 seconds, achieves an over-grinding determination accuracy of 98.7%, and significantly reduces energy waste caused by excessive fine grinding. It effectively avoids the excessive fiber fragmentation phenomenon commonly found in traditional coarse grinding processes.
[0020] In some specific implementations, during the coarse grinding process, an online fiber length detector is used to determine the fiber state. The average fiber length threshold is set to 2 / 3 of the aramid fiber chopped raw material. When the detected value is lower than this value, the grinding disc speed is automatically reduced by 10%-15%. When the peak value of the acoustic emission signal is higher than 20-25 kHz, it is determined that the buffing rate meets the standard, and the coarse grinding is automatically stopped.
[0021] In the fine grinding stage, fine-toothed grinding discs are used to separate the fibers into bristles, forming fuzz on the surface of the fiber backbone while preserving the integrity of the fiber backbone.
[0022] The tooth width of the fine-tooth grinding disc is preferably in the range of 0.8 to 1.4 mm. For example, it can be 0.8, 1.0, 1.1, 1.2, 1.3, 1.4 mm, or any of the above values as the upper or lower limit.
[0023] The tooth height range is preferably 4.0 to 4.6 mm. For example, it can be 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6 mm, or any of the above values as the upper or lower limit.
[0024] The preferred tooth pitch range is 5.5 to 8.5 mm. For example, it can be 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5 mm, or any of the above values as the upper or lower limit.
[0025] In the dynamic graded feedback stage, a graded control strategy is adopted based on fiber state. When there is a risk of insufficient fibrillation or over-grinding, the mill speed is dynamically controlled. Multi-level linkage control achieves a closed-loop system for finished product quality. Through online fiber length detection and fibrillation rate compensation, secondary microfibrillation in the fine grinding zone is triggered, achieving a high specific surface area while preserving fiber length, thus improving the adhesion of aramid pulp to the fillers in the brake pads. In continuous production trials, this system achieved: fiber length CV value ≤8%, fibrillation rate fluctuation range ±2%, and a 19.6% reduction in unit product energy consumption.
[0026] In some specific implementation schemes, during the fine grinding process, an online fiber length detector is used to determine the fiber state. When the online fiber length detector detects a value lower than 1.2-1.5 mm and the peak value of the acoustic emission signal is lower than 35-45 kHz, a secondary fine grinding is triggered and buffing rate compensation is performed. The grinding disc speed is automatically increased by 15%-25%, and the speed is reduced by 10%-15% during over-grinding.
[0027] In this invention, the coarse grinding stage and the fine grinding stage are each equipped with 3 to 5 stages of series grinding equipment. This series connection ensures that the material passes through each stage of grinding equipment in sequence, ensuring that the material undergoes the same grinding process, resulting in more uniform aramid pulp properties.
[0028] This invention is the first to construct a real-time feedback mechanism based on online fiber length detection, and combines it with a fiber state grading control strategy and a dynamic grading feedback system to achieve precise quantitative control of the fiber cutting process. This technical solution, through real-time monitoring and dynamic adjustment, can effectively suppress excessive fiber cutting and significantly improve fiber buffing rate and specific surface area. Through synergistic optimization and closed-loop control of process parameters, it achieves a systematic improvement in the quality of aramid pulp products while increasing production efficiency, providing a new technical path for industry technological upgrading.
[0029] The present invention also provides a high-adhesion aramid pulp prepared by the above method.
[0030] The experimental results show that the adhesion of the aramid pulp prepared by this invention is higher than 40%.
[0031] Based on this, the present invention provides the application of the high-adhesion aramid pulp prepared by the above method as a brake pad reinforcing material.
[0032] The high-adhesion aramid pulp provided by this invention can effectively improve the adhesion and preform strength of brake pads, reduce the wear of friction materials, and enable brake pads to maintain high mechanical properties even at high temperatures.
[0033] Compared with the prior art, the present invention provides a method for continuous production of high-adhesion aramid pulp, comprising: sequentially subjecting a dispersion of aramid fiber chopped raw materials to coarse grinding and fine grinding to obtain high-adhesion aramid pulp; wherein the coarse grinding uses wide-tooth grinding discs; and the fine grinding uses fine-tooth grinding discs.
[0034] This invention employs a combination of wide-tooth and fine-tooth grinding discs in the pulping process, constructing a hierarchical control mechanism based on the physical-mechanical principles of fiber: the wide-tooth grinding discs utilize a wide-tooth-stepped tooth profile structure with rounded tooth ends to achieve the effect of "long fiber retention + moderate fibrillation," thereby enabling precise control of fiber length distribution and optimized dispersion. The fine-tooth grinding discs, relying on a comb-like design and staggered arrangement to form a micro-tooth array structure, enhance the broom-like effect, promoting the formation of a uniform fuzzy structure on the fiber backbone while maintaining the overall strength. This combined process, through the coupled control of grinding disc tooth profile parameters and operating parameters, constructs a precise control system for fiber morphology evolution, providing a process solution with both efficiency and energy consumption advantages for the industrial preparation of high-performance aramid pulp.
[0035] Meanwhile, the method provided by this invention adopts a continuous production method from fiber filament to finished pulp. It uses a series continuous refining process to produce high-adhesion para-aramid pulp from chopped para-aramid raw materials through dispersion, coarse grinding, and fine grinding. The pulp mass percentage remains constant throughout the production process and does not require adjustment. This continuous production method solves the quality fluctuation problem of traditional intermittent single-tank refining, improves production efficiency, and reduces labor costs. Furthermore, the different refining disc designs used at different refining stages achieve high specific surface area while preserving the strength of the fiber backbone. When used as a reinforcing material in brake pads, it exhibits high adhesion to the fillers in the brake pads, improving the strength of the brake pad blank, reducing wear of friction materials, and maintaining high mechanical properties even at high temperatures, meeting the requirements of high-end friction materials for para-aramid pulp. Attached Figure Description
[0036] Figure 1 A 50x magnified micrograph of the aramid pulp prepared in Example 3;
[0037] Figure 2 A microscope image magnified 50 times for the aramid pulp prepared in Comparative Example 1;
[0038] Figure 3 A microscope image magnified 50 times for the aramid pulp prepared in Comparative Example 2;
[0039] Figure 4 The process flow diagram of the continuous production method of high-adhesion aramid pulp provided by the present invention. Detailed Implementation
[0040] To further illustrate the present invention, a detailed description is provided below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.
[0041] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0042] Example 1
[0043] 1) Aramid filament fibers are cut into 6mm aramid staple fibers. The aramid staple fibers and pure water are continuously added to the dispersion tank through an automatic weighing system. The para-aramid staple raw material is dispersed by stirring, and the slurry concentration is 4.0%.
[0044] 2) The raw material slurry in the dispersion tank in 1) is transported to the coarse grinding zone. Wide-tooth grinding discs with a tooth width of 4 mm, a tooth height of 5 mm, and a tooth pitch of 8 mm are used. The coarse grinding slurry is obtained through a three-stage coarse grinding process with a power of 185KW. The fiber state is determined by an online fiber length detector. The average fiber length threshold is set to 4 mm. When the detected value is lower than 4 mm, the grinding disc speed is automatically reduced by 10-15%. When the peak value of the acoustic emission signal is higher than 25 kHz, the buffing rate is determined to be up to standard, and the coarse grinding is automatically stopped.
[0045] 3) The coarse grinding slurry from 2) is transported to the fine grinding zone. Fine-tooth grinding discs with a tooth width of 0.8 mm, a tooth height of 4 mm, and a tooth pitch of 5.5 mm are used. The slurry is refined through a five-stage 280KW fine grinding process. When the fiber length detected by the online detector is lower than 1.2 mm and the peak value of the acoustic emission signal is lower than 40 kHz, a second fine grinding is triggered and buffing rate compensation is performed. The grinding disc speed is automatically increased by 20%, and the speed is reduced by 10% during over-grinding.
[0046] 4) The finely ground slurry from 3) is conveyed to the filter screen for drying through the central slurry distributor. After vacuum filtration, the moisture content of the pulp lumps is 50% to 90%. After passing through the high-pressure air dewatering and drying equipment, the moisture content of the pulp lumps is 8% to 15%.
[0047] 5) The dried para-aramid pulp block from step 4) is transported to the opening equipment for opening. After opening, the finished para-aramid pulp is obtained through an automatic weighing and packaging system.
[0048] Example 2
[0049] 1) Aramid filament fibers are cut into 6mm aramid staple fibers. The aramid staple fibers and pure water are continuously added to the dispersion tank through an automatic weighing system. The para-aramid staple raw material is dispersed by stirring, and the slurry concentration is 5.0%.
[0050] 2) The raw material slurry in the dispersion tank in 1) is transported to the coarse grinding zone and subjected to a four-stage coarse grinding process with a power of 280KW (tooth width 4.5 mm, tooth height 6 mm and tooth pitch 10 mm) to obtain coarse grinding slurry;
[0051] 3) The coarse grinding slurry from 2) is transported to the fine grinding zone and undergoes a four-stage 220KW fine grinding process (tooth width 1 mm, tooth height 4.2 mm and tooth pitch 6.5 mm) to obtain the fine grinding slurry;
[0052] 4) The finely ground slurry from 3) is conveyed to the filter screen for drying through the central slurry distributor. After vacuum filtration, the moisture content of the pulp lumps is 50% to 90%. After passing through the high-pressure air dewatering and drying equipment, the moisture content of the pulp lumps is 8% to 15%.
[0053] 5) The dried para-aramid pulp block from step 4) is transported to the opening equipment for opening. After opening, the finished para-aramid pulp is obtained through an automatic weighing and packaging system.
[0054] Example 3
[0055] 1) Aramid filament fibers are cut into 6mm aramid staple fibers. The aramid staple fibers and pure water are continuously added to a dispersion tank through an automatic weighing system. The para-aramid staple raw material is dispersed by stirring, and the slurry concentration is 6.0%.
[0056] 2) The raw material slurry in the dispersion tank in 1) is transported to the coarse grinding zone and subjected to a three-stage coarse grinding process with a power of 355KW (tooth width 5.5 mm, tooth height 7 mm and tooth pitch 14 mm) to obtain coarse grinding slurry;
[0057] 3) The coarse grinding slurry from 2) is transported to the fine grinding zone and undergoes a five-stage 132KW fine grinding process (tooth width 1.2mm, tooth height 4.4mm and tooth pitch 7.5mm) to obtain the fine grinding slurry;
[0058] 4) The finely ground slurry from 3) is conveyed to the filter screen for drying through the central slurry distributor. After vacuum filtration, the moisture content of the pulp lumps is 50% to 90%. After passing through the high-pressure air dewatering and drying equipment, the moisture content of the pulp lumps is 8% to 15%.
[0059] 5) The dried para-aramid pulp block from step 4) is transported to the opening equipment for opening. After opening, the finished para-aramid pulp is obtained through an automatic weighing and packaging system.
[0060] Example 4
[0061] 1) Aramid filament fibers are cut into 6mm aramid staple fibers. The aramid staple fibers and pure water are continuously added to the dispersion tank through an automatic weighing system. The para-aramid staple raw material is dispersed by stirring, and the slurry concentration is 7.0%.
[0062] 2) The raw material slurry in the dispersion tank in 1) is transported to the coarse grinding zone and subjected to a four-stage coarse grinding process with a power of 500KW (tooth width 6.5 mm, tooth height 8 mm and tooth pitch 16 mm) to obtain coarse grinding slurry;
[0063] 3) The coarse grinding slurry from 2) is transported to the fine grinding zone and undergoes a four-stage 75KW fine grinding process (tooth width 1.4 mm, tooth height 4.6 mm and tooth pitch 8.5 mm) to obtain the fine grinding slurry;
[0064] 4) The finely ground slurry from 3) is conveyed to the filter screen for drying through the central slurry distributor. After vacuum filtration, the moisture content of the pulp lumps is 50% to 90%. After passing through the high-pressure air dewatering and drying equipment, the moisture content of the pulp lumps is 8% to 15%.
[0065] 5) The dried para-aramid pulp block from step 4) is transported to the opening equipment for opening. After opening, the finished para-aramid pulp is obtained through an automatic weighing and packaging system.
[0066] Comparative Example 1
[0067] The difference from Example 3 is that wide-tooth grinding discs are used in both the coarse grinding and fine grinding stages.
[0068] Comparative Example 2
[0069] The difference from Example 3 is that fine-tooth grinding discs are used in both the coarse grinding and fine grinding stages.
[0070] The parameters and experimental results of each embodiment and comparative example are shown in Table 2.
[0071] Brake pads were prepared using the para-aramid pulp products prepared in Examples 1-4 and Comparative Examples 1-2 as reinforcing materials. The composition of the brake pads is shown in Table 1.
[0072] Table 1 Brake pad composition
[0073]
[0074] In Table 1, aramid refers to the para-aramid pulp product prepared by any of Examples 1-4 and Comparative Examples 1-2.
[0075] The coefficient of friction of brake pads is shown in Table 2.
[0076] Table 2
[0077]
[0078] The method for testing adhesion is as follows: the ratio of barite to aramid pulp is 98:2. Mix the mixture in a mixer for 10 minutes, weigh 100 grams of the mixture and place it in a 30-mesh sieve. After sieving for 10 minutes, weigh the remaining weight on the sieve.
[0079] Figure 1 The image shown is a 50x magnified micrograph of the para-aramid pulp product prepared in Example 3. It can be seen that the aramid pulp prepared by using a combination of wide-tooth and fine-tooth grinding discs retains the main fiber structure to a high degree. At the same time, the fiber surface exhibits a high-density hair distribution, giving it a high specific surface area and thus significantly enhancing its adhesion to the mixed materials.
[0080] Figure 2This is a 50x magnified micrograph of the finished para-aramid pulp prepared in Comparative Example 1. In both the coarse and fine grinding stages, wide-tooth grinding discs were used in Comparative Example 1. The main effect was to cut the fibers at high speed, resulting in clear fiber trunks. However, the fiber surface fibrillation was weak, with few surface hairs, low beating degree and specific surface area, poor adhesion to the mixture, and low adhesion force.
[0081] Figure 3 This is a 50x magnified micrograph of the finished para-aramid pulp prepared in Comparative Example 2. Comparative Example 2 uses fine-tooth grinding discs in both the coarse and fine grinding stages. The main effect is to separate and bristle the fibers, but the cutting effect on the fibers is weak. In the end, the main fiber stem splits and all the fibers are broken into a fuzzy state. The beating degree and specific surface area are high, but the broken fuzzy structure cannot play a skeletal support role in the mixture, so the adhesion is low.
[0082] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A method for continuous production of high-adhesion aramid pulp, comprising: The dispersion of aramid fiber chopped raw material was subjected to coarse grinding and fine grinding in sequence to obtain aramid pulp with high adhesion. The coarse grinding uses wide-tooth grinding discs; The fine grinding process uses fine-tooth grinding discs.
2. The method for continuous production of high-adhesion aramid pulp according to claim 1, characterized in that, The aramid fiber is a para-aramid fiber.
3. The method for continuous production of high-adhesion aramid pulp according to claim 1, characterized in that, The length of the aramid fiber chopped raw material is 6~12mm.
4. The method for continuous production of high-adhesion aramid pulp according to claim 1, characterized in that, The concentration of the aramid fiber chopped raw material dispersion is 4% to 7%.
5. The method for continuous production of high-adhesion aramid pulp according to claim 1, characterized in that, The tooth width of the wide-tooth grinding disc ranges from 4 to 6.5 mm, the tooth height ranges from 5 to 8 mm, and the tooth pitch ranges from 8 to 16 mm.
6. The method for continuous production of high-adhesion aramid pulp according to claim 1, characterized in that, The fine-tooth grinding disc has a tooth width ranging from 0.8 to 1.4 mm, a tooth height ranging from 4.0 to 4.6 mm, and a tooth pitch ranging from 5.5 to 8.5 mm.
7. The method for continuous production of high-adhesion aramid pulp according to claim 1, characterized in that, During the coarse grinding and fine grinding processes, an online fiber length detector is used to determine the fiber state.
8. The method for continuous production of high-adhesion aramid pulp according to claim 7, characterized in that, During the coarse grinding process, the average fiber length threshold is set to 2 / 3 of the aramid fiber chopped raw material. When the detected value is lower than this value, the grinding disc speed is automatically reduced by 10%-15%. When the peak value of the acoustic emission signal is higher than 20-25 kHz, it is determined that the buffing rate meets the standard, and the coarse grinding is automatically stopped. During the fine grinding process, an online fiber length detector is used to determine the fiber state. When the online fiber length detector detects a value lower than 1.2-1.5 mm and the peak value of the acoustic emission signal is lower than 35-45 kHz, a secondary fine grinding is triggered and buffing rate compensation is performed. The grinding disc speed is automatically increased by 15%-25%, and the speed is reduced by 10%-15% during over-grinding.
9. The high-adhesion aramid pulp prepared by the method according to any one of claims 1 to 8.
10. The application of the high-adhesion aramid pulp prepared by the method according to any one of claims 1 to 8 as a brake pad reinforcing material.