From paper pulp to high-performance materials: horizontal bead mills drive the industrialization process of bio based new materials
From paper pulp to high-performance materials: horizontal bead mills drive the industrialization process of bio based new materials
In the paper industry, fine grinding of pulp is a key step in improving the properties of cellulose materials. As an efficient mechanical grinding equipment, the horizontal bead mill achieves micro nano processing of fibers through physical shear force, providing important technical support for the development of high-performance micro/nano fiber materials. The application of this equipment in the field of pulp grinding not only breaks through the performance limitations of traditional cellulose materials, but also promotes the industrialization process of bio based new materials in high-end fields such as electronics, healthcare, and packaging.
Cellulose, as the most abundant renewable resource in nature, has a rigid structure formed by β-1,4-glycosidic bonds connecting its molecular chains. This special structure gives it a theoretical elastic modulus of 7.5 GPa and a theoretical strength of 3 GPa. However, cellulose in natural plant fibers exists in the form of microfibril bundles, which are enveloped by a matrix formed by hemicellulose and lignin, resulting in actual mechanical properties far below theoretical values. By using a horizontal bead mill for mechanical fiber breaking treatment, this binding structure can be effectively broken down, decomposing the original fibers with a diameter of 20-50 μm into micro/nano fibers with a diameter less than 100nm, increasing the specific surface area of the material from 1-2m ²/g to 200-400m ²/g, thereby fully releasing the performance potential of cellulose.
In terms of optimizing specific process parameters, the control of grinding intensity and time is particularly crucial. Experimental data shows that when using a grinding speed of 1500r/min, a grinding disc gap of -10 μm can generate sufficient shear force to cause longitudinal fiber splitting. As the grinding time increased from 5 minutes to 120 minutes, the diameter of eucalyptus pulp fibers showed a stepwise decrease: at 30 minutes, the fibers began to separate into fibers, reaching an average diameter of 420nm at 60 minutes, and forming a network interwoven structure of 128nm after 120 minutes. It is worth noting that prolonged grinding time can lead to a sharp increase in energy consumption. After more than 90 minutes, the rate of change in fiber diameter decreases to below 5%, and the economic benefits of continuing grinding significantly decrease.
The synergistic effect of biological pretreatment and mechanical grinding of cellulase provides a more efficient solution for the preparation of micro/nanofibers. During enzymatic hydrolysis, cellulase specifically attacks the amorphous region of fibers, causing erosion holes on the surface of the fibers. When the enzyme dosage is controlled at 15-20 FPU/g (filter paper enzyme activity unit) and the action time is 6 hours, the fiber crystallinity can be reduced from 60% to 45%. At this time, mechanical grinding can reduce energy consumption by 30%. However, it should be noted that after the enzymatic hydrolysis time exceeds 8 hours, the degradation rate of cellulose tends to plateau, while the yield of reducing sugars increases to over 12%, resulting in waste of raw materials. By optimizing this bio mechanical combined process, the final micro/nanofiber diameter distribution is more uniform, with a length to diameter ratio of up to 50-100, significantly better than products prepared by a single mechanical method.
The structural design of a horizontal bead mill has a decisive impact on the grinding effect. Modern high-performance bead mills adopt a multi-stage grinding chamber design, combined with a 0.3-0.5mm grinding medium made of zirconia material, which can achieve gradient utilization of energy. The first stage cavity mainly completes the initial dissociation of fiber bundles, the second stage focuses on the refinement of fibers, and the third stage achieves size homogenization. This design saves 40% energy compared to traditional single chamber devices, while avoiding fiber breakage caused by excessive grinding. In terms of temperature control, an external circulation cooling system is used to maintain the slurry temperature below 40 ℃, which can prevent a decrease in cellulose polymerization degree caused by high temperatures.
In the specific application of the paper industry, micro/nano fibers prepared by horizontal bead mills exhibit multiple values. When used as a reinforcing material, adding 5wt% of micro/nano fibers can increase the tensile strength of paper by more than 50%; In the field of specialty paper, battery separator paper with air permeability ranging from 1-100 μ m/(Pa · s) can be prepared by adjusting the fiber size; More noteworthy is that by combining fibers with a diameter less than 100nm with polylactic acid, a fully biodegradable packaging material with a tensile strength of 120MPa can be produced. This material has an oxygen permeability two orders of magnitude lower than ordinary plastics and has unique advantages in the field of food preservation.
From the perspective of industrial development, horizontal grinding technology is driving the transformation of the paper industry towards high value. According to industry statistics, the market value of micro/nano fiber products processed using this technology can reach 8-10 times that of ordinary pulp. In emerging fields such as electronic paper substrates, medical dressings, and flexible sensors, the annual demand growth rate for cellulose microfibers/nano fibers remains above 25%. However, it should also be noted that the current equipment still has the problem of high energy consumption when processing high concentration slurries with viscosity higher than 2000cP. In the future, developing a new type of grinding system with low shear force field coupled with ultrasonic assistance may become a key direction to break through technological bottlenecks.
With the increasingly strict environmental regulations and the promotion of carbon neutrality goals, cellulose micro/nano fiber materials based on horizontal grinding technology are showing great potential to replace petrochemical based materials. This development model that combines traditional paper making techniques with modern nanotechnology not only improves the efficiency of fiber resource utilization, but also creates a new sustainable development path of "replacing plastic with paper". From the perspective of technological evolution, the next generation of intelligent grinding systems will integrate online particle size monitoring and adaptive control systems, which is expected to control the production accuracy of micro/nano fibers within ± 10nm, opening up broader space for the precise application of cellulose materials.
In the paper industry, fine grinding of pulp is a key step in improving the properties of cellulose materials. As an efficient mechanical grinding equipment, the horizontal bead mill achieves micro nano processing of fibers through physical shear force, providing important technical support for the development of high-performance micro/nano fiber materials. The application of this equipment in the field of pulp grinding not only breaks through the performance limitations of traditional cellulose materials, but also promotes the industrialization process of bio based new materials in high-end fields such as electronics, healthcare, and packaging.
Cellulose, as the most abundant renewable resource in nature, has a rigid structure formed by β-1,4-glycosidic bonds connecting its molecular chains. This special structure gives it a theoretical elastic modulus of 7.5 GPa and a theoretical strength of 3 GPa. However, cellulose in natural plant fibers exists in the form of microfibril bundles, which are enveloped by a matrix formed by hemicellulose and lignin, resulting in actual mechanical properties far below theoretical values. By using a horizontal bead mill for mechanical fiber breaking treatment, this binding structure can be effectively broken down, decomposing the original fibers with a diameter of 20-50 μm into micro/nano fibers with a diameter less than 100nm, increasing the specific surface area of the material from 1-2m ²/g to 200-400m ²/g, thereby fully releasing the performance potential of cellulose.
In terms of optimizing specific process parameters, the control of grinding intensity and time is particularly crucial. Experimental data shows that when using a grinding speed of 1500r/min, a grinding disc gap of -10 μm can generate sufficient shear force to cause longitudinal fiber splitting. As the grinding time increased from 5 minutes to 120 minutes, the diameter of eucalyptus pulp fibers showed a stepwise decrease: at 30 minutes, the fibers began to separate into fibers, reaching an average diameter of 420nm at 60 minutes, and forming a network interwoven structure of 128nm after 120 minutes. It is worth noting that prolonged grinding time can lead to a sharp increase in energy consumption. After more than 90 minutes, the rate of change in fiber diameter decreases to below 5%, and the economic benefits of continuing grinding significantly decrease.
The synergistic effect of biological pretreatment and mechanical grinding of cellulase provides a more efficient solution for the preparation of micro/nanofibers. During enzymatic hydrolysis, cellulase specifically attacks the amorphous region of fibers, causing erosion holes on the surface of the fibers. When the enzyme dosage is controlled at 15-20 FPU/g (filter paper enzyme activity unit) and the action time is 6 hours, the fiber crystallinity can be reduced from 60% to 45%. At this time, mechanical grinding can reduce energy consumption by 30%. However, it should be noted that after the enzymatic hydrolysis time exceeds 8 hours, the degradation rate of cellulose tends to plateau, while the yield of reducing sugars increases to over 12%, resulting in waste of raw materials. By optimizing this bio mechanical combined process, the final micro/nanofiber diameter distribution is more uniform, with a length to diameter ratio of up to 50-100, significantly better than products prepared by a single mechanical method.
The structural design of a horizontal bead mill has a decisive impact on the grinding effect. Modern high-performance bead mills adopt a multi-stage grinding chamber design, combined with a 0.3-0.5mm grinding medium made of zirconia material, which can achieve gradient utilization of energy. The first stage cavity mainly completes the initial dissociation of fiber bundles, the second stage focuses on the refinement of fibers, and the third stage achieves size homogenization. This design saves 40% energy compared to traditional single chamber devices, while avoiding fiber breakage caused by excessive grinding. In terms of temperature control, an external circulation cooling system is used to maintain the slurry temperature below 40 ℃, which can prevent a decrease in cellulose polymerization degree caused by high temperatures.
In the specific application of the paper industry, micro/nano fibers prepared by horizontal bead mills exhibit multiple values. When used as a reinforcing material, adding 5wt% of micro/nano fibers can increase the tensile strength of paper by more than 50%; In the field of specialty paper, battery separator paper with air permeability ranging from 1-100 μ m/(Pa · s) can be prepared by adjusting the fiber size; More noteworthy is that by combining fibers with a diameter less than 100nm with polylactic acid, a fully biodegradable packaging material with a tensile strength of 120MPa can be produced. This material has an oxygen permeability two orders of magnitude lower than ordinary plastics and has unique advantages in the field of food preservation.
From the perspective of industrial development, horizontal grinding technology is driving the transformation of the paper industry towards high value. According to industry statistics, the market value of micro/nano fiber products processed using this technology can reach 8-10 times that of ordinary pulp. In emerging fields such as electronic paper substrates, medical dressings, and flexible sensors, the annual demand growth rate for cellulose microfibers/nano fibers remains above 25%. However, it should also be noted that the current equipment still has the problem of high energy consumption when processing high concentration slurries with viscosity higher than 2000cP. In the future, developing a new type of grinding system with low shear force field coupled with ultrasonic assistance may become a key direction to break through technological bottlenecks.
With the increasingly strict environmental regulations and the promotion of carbon neutrality goals, cellulose micro/nano fiber materials based on horizontal grinding technology are showing great potential to replace petrochemical based materials. This development model that combines traditional paper making techniques with modern nanotechnology not only improves the efficiency of fiber resource utilization, but also creates a new sustainable development path of "replacing plastic with paper". From the perspective of technological evolution, the next generation of intelligent grinding systems will integrate online particle size monitoring and adaptive control systems, which is expected to control the production accuracy of micro/nano fibers within ± 10nm, opening up broader space for the precise application of cellulose materials.
