COLOWE's New Breakthrough in Biodegradable Material Granulation - Why Is The Co Rotating Twin-screw Extruder A Better Solution For Biodegradable Material Granulation?
1, An accelerating track and an underestimated processing challenge
The global biodegradable plastic market has climbed to 12.84 billion US dollars in 2025, an increase of 18.7% compared to the previous year. The European Bioplastics 2025 market data report states that the global production capacity of bio based plastics is expected to double from 2.31 million tons in 2025 to approximately 4.69 million tons in 2030. The policy side is also accelerating: the revised version of the EU Packaging and Packaging Waste Regulation has been officially implemented in 2026, requiring that the recycled content in all plastic packaging should not be less than 30% by 2030.
However, the rapid expansion of the demand side has obscured a practical problem: the processing window for biodegradable material granulation is extremely narrow. The ester bonds in PLA and PBAT molecular chains are easily hydrolyzed or thermally degraded at high temperatures. Once the screw configuration is improper and the melt temperature is out of control, it can lead to a sudden drop in molecular weight, yellowing of particles, and significant loss of mechanical properties. In other words, biodegradable materials do not lack a market, what is lacking is processing equipment that can stably produce them.
2, The three major technical thresholds for granulation of biodegradable materials
2.1 Thermal sensitivity: The temperature window is only a few tens of degrees
The processing temperature window for conventional PE or PP is wide, while the melting processing window for PLA is usually only between 170 ℃ and 210 ℃. Exceeding the upper limit, thermal degradation is irreversible; Below the lower limit, insufficient plasticization. Industry research clearly states that the core principles of PLA/PBAT extrusion granulation are "low temperature, low shear, and high distribution". This poses extremely high requirements for the temperature control accuracy and screw combination design of the co rotating twin-screw extruder.
2.2 Shear sensitivity: balance between dispersion and degradation
Degradable materials often need to be blended with fillers such as starch, bamboo powder, and calcium carbonate, and must rely on sufficient shear force to achieve uniform dispersion. But excessive shear can also break the molecular chain. This requires the co rotating twin-screw extruder to achieve "zone differentiation" in screw configuration - mild conveying in the feed section, precise kneading in the middle section, and low-pressure homogenization in the rear section, with each section's thermal history within a controllable range.
2.3 Moisture and residual monomers: Exhaust capacity determines quality
The residual monomers and moisture in biodegradable resins are the main sources of bubbles and coking during the granulation process. Industry practice has shown that the combination of co rotating twin-screw extruders and online devolatilization technology can improve product performance stability by more than 20%. The multi-stage vacuum exhaust design is a key link in ensuring the quality of biodegradable material granulation.
3, The 'Symptomatic Solution' of COLOWE co rotating twin-screw extruder
3.1 Ultra long diameter ratio+multi section cylinder: making thermal history controllable
The 35 type co rotating twin-screw extruder launched by Nanjing Kelongwell Chemical Machinery Co., Ltd. adopts a 60:1 ultra long diameter ratio design and a modular configuration of 15 cylinder bodies. The significance of the aspect ratio is that the material has more ample space to gradually heat up and plasticize, rather than being "violently" heated over a short distance. The front section is equipped with a main feeding and forced conveying area, the middle section is composed of multiple kneading blocks for gentle mixing, and the rear section is equipped with dual vacuum exhaust ports to remove moisture and residual monomers. The actual measurement shows that this configuration can control the melt temperature fluctuation within ± 1 ℃, and fundamentally avoid gel particles and black spots.
3.2 High specific torque+low-speed strategy: sufficient shear without excessive shear
COLOWE's co rotating twin-screw extruder is equipped with a high torque gearbox, with a specific torque of 11 Nm/cm ³, and operates at low to medium speeds of 330rpm. High specific torque means that sufficient shear force can be output at lower speeds, ensuring uniform dispersion of the packing and avoiding shear heat accumulation caused by high speeds. This strategy is particularly suitable for PLA/PBAT systems - molecular chains are dispersed and mixed in a mild shear field, rather than being "torn apart".
3.3 Energy consumption data: Hard indicators of cost-effective extruders
In the continuous production of PP+40% calcium carbonate filled granulation using a certain model of co rotating twin-screw extruder from Kelongwell, the power consumption per ton has been reduced to 0.25 kWh/kg, which is about 15% to 20% energy-saving compared to the common industry level. In the scenario of biodegradable material granulation, the industry average specific energy consumption of equipment of the same specifications is 0.28-0.32 kWh/kg, while the actual measurement by Kelongwell is stable at 0.24 kWh/kg, saving about 20% energy. Based on an annual production line of 5000 tons of modified plastics, it can save about 120000 yuan in electricity costs and reduce indirect carbon emissions by about 96 tons of CO ₂ e. This is the actual meaning of a cost-effective extruder: it is not cheap to buy, but economical to use.
4, First contact with biodegradable material granulation? Three key questions and answers
Q1: This is my first time doing biodegradable material granulation. Is a co rotating twin-screw extruder suitable?
fit. The co rotating twin-screw extruder, with its modular screw components and excellent self-cleaning performance, is the mainstream choice for modified and regenerated granulation worldwide. Kelongwell's modular threaded components and split barrel design allow the screw configuration to be reassembled like building blocks, reducing cleaning time by about 40% compared to traditional models, which is very suitable for the initial development rhythm of small batches and multiple varieties.
Q2: Degradable materials are so sensitive to temperature, will the equipment be prone to problems?
The key lies in the compatibility between the temperature control system and the screw design. COLOWE provides a "turnkey" service from material testing, screw configuration recommendation to whole line scheme design. Customers can send materials for testing, complete feasibility verification in the experimental center, and then scale up to mass production. For international customers, we also provide English operation manuals and remote installation guidance.
Q3: With limited budget, will the opportunity to squeeze out high cost-effectiveness not shrink in core configurations?
No. COLOWE's cost-effective co rotating twin-screw extruder maintains high standards in core components such as gearboxes and cylinder liners: the gearbox adopts carburizing quenching and gear grinding technology, and the cylinder liner is made of bimetallic centrifugal casting, with wear resistance three times higher than that of nitrogen doped steel. The cost-effectiveness is reflected in the overall cost control and full lifecycle operation and maintenance costs, rather than compromising on core parameters.
5, Conclusion
The core contradiction of biodegradable material granulation is the conflict between the thermal sensitivity of the material itself and the heat and shear required for the processing. The reason why the co rotating twin-screw extruder has become a key equipment in this field is that it can resolve this conflict through modular design, precise temperature control, and graded shearing, in the coordination of each screw component and each section of the cylinder. Nanjing Kelongwell Chemical Machinery Co., Ltd. has been dedicated to the research and development of co rotating twin-screw extruders for over 20 years, and has delivered over 2000 sets of equipment to more than 60 countries worldwide. For international customers who are trying to develop new biodegradable materials, choosing a cost-effective extruder that truly understands the processing characteristics of biodegradable materials is the first step in moving the formula from the laboratory to mass production.
