The plastics industry produces special or technical compounds used to make parts and products in a wide range of industries: transport and automotive, packaging, appliances, etc. Twin-screw extrusion technology is particularly well suited to make these complex plastics that incorporate up to five or six chemical components. These components have different characteristics, such as their viscosity or melting threshold, and are used in a variety of post-forming processes such as injection moulding machines, blown film machines, etc.
Clextral has developed its expertise in technical compounds for over 50 years, supplying systems to major chemical companies and working closely with private and public R&D centers.
Special compounds, usually provided in granular or pellet form, are polymers with specific base characteristics, which are then enhanced in twin-screw extrusion processes with the addition of different organic or non-organic substances to give them special functional features.
For example, rubber may be added for greater flexibility, flame retardant can make them safer, and other additives can provide greater strength, heat conductivity, insulation, resistance to impact, etc. Clextral lines produce the full range of these products based on polyamides, polyolefins, elastomers, etc.
Clextral twin-screw process features
Clextral twin-screw lines offer major advantages in processing special and technical compounds:
- Optimum product quality and process flexibility
- Dedicated screw profiles, ensuring mixing quality and pigment dispersion
- Pigment and polymer pre-mixing capabilities, fed by dosing systems upstream or injected at subsequent stages in the process
- High torque levels for efficient shearing and homogeneous mixing
- Adaptation of residence time for heat-sensitive materials
- Slide-open barrels for easy access to screws and other parts, facilitating reconfiguration of screws, reducing down time between batches and simplifying changeover
- Self-cleaning screws to facilitate maintenance and color changes.
- Very accurate screw surface machining, to prevent infiltration of materials between screw sections