In the blow molding sector, sustainability has become a strategic factor. Bottle manufacturers are increasingly adopting post-consumer recycled (PCR) materials and biodegradable polymers to reduce environmental impact and meet new market demands.
However, the use of these materials introduces significant challenges in Extrusion Blow Molding processes, requiring advanced and innovative technological solutions.
Challenges of PCR materials in Extrusion Blow Molding
PCR materials exhibit variable rheological properties, which can change significantly from batch to batch. This variability often leads:
- process instability
- un-melted fragments
- black spots
- inconsistencies in bottle weight
Similarly, biodegradable polymers, while environmentally promising, present comparable challenges:
- they are sensitive to processing temperature
- require precise melting
- need longer residence times in extruders to achieve homogeneous flow
The extrusion screw: a key element in the process
An optimized screw is more than just a mechanical component; it is the key to controlling:
- melting
- mixing
- material stability
A properly designed screw enables better handling of complex materials such as PCR and biodegradable polymers, reducing defects and improving production efficiency.
Specific screw design for processing sustainable materials
To achieve optimal results in Extrusion Blow Molding, screw design must be adapted to the specific characteristics of the materials, focusing on 3 critical zones:
1. Feeding zone
Ensures a constant and regular material supply, compensating for variations in pellet size, density, and moisture content typical of recycled materials.
2. Compression zone
Provides gradual and controlled melting, enabling full homogenization and reducing defects such as unmelted granules. Extended compression sections and carefully optimized channel geometry are essential for PCR resins.
3. Metering and dispersion zone
Ensures a uniform output and perfect mixing before the molten material reaches the filtration system and die head. This guarantees stable weight, uniform appearance, and high-quality bottles.
Impurity filtration systems for recycled materials
In extrusion blow molding processes using recycled materials, filtration systems are essential as they capture impurities and ensure that the final product meets the highest possible standards of quality and reliability.
Bimetallic screws for post-consumer recycled (PCR) materials
Bimetallic screws with an L/D ratio of 28, designed and optimized for processing these materials, allow manufacturers to integrate sustainable solutions into their production processes without compromising efficiency, reliability, or quality—while also turning environmental sustainability into a concrete competitive advantage for the industry.
