Semicrystalline thermoplastics, like polypropylene, polyethylene and polyamide are preferred materials in the packaging industry. These materials change at the glass transition temperature into a partial crystalline structure, where spherulites are created. These spherulites spoil the transparency by refraction of light. In order to prevent this phenomenon the melt must be cooled as fast as possible.
An instantly chilled partial crystalline plastic, e.g. Polyamide, stays amorphous. The film remains highly transparent due to the lack of makrosperulite build up. Side effects of the procedure include: high gloss, extreme puncture and tear resistance and excellent thermo-formability rising from its amorphous structure.
Due to the use of water and the effects of gravity on it, the extrusion has been designed in downward vertical direction. The air-cooling ring, with the possibility of automatic thickness tolerance regulation by segmented air flow if requested, serves mainly as a stabilizer for a defined blow-up ratio. After the desired tubular diameter is reached, the film immediately enters the cooling chamber where it is shock cooled by water rather than the traditional frost line approach and fast crystallization. It is the expertise of Reifenhäuser Blown Film Plamex to optimize this process with efficient water exchange, achieving a turbulence free procedure removing maximum heat in a minimum amount of time with remarkable optical properties. An installed vacuum settles the shape of the bubble and allows the film to leave the cooling chamber almost dry. Approximately 10Kcal / cm circumference can be extracted (PA6, 500 kg/h, ΔT 190, dlf. 800mm, 100 µm).
With respect to achieving a desired stiffness of the film or influencing its curling effects, we highly recommend the integration of SSP (Solid State Postcrystallization) aggregate, which is positioned after the reversing haul-off. With this system, the amorphous film is pulled over a couple of defined tempered rolls, adjusting the film according to desired specifications. No adverse effects on transparency and thermo-formability occur during SSP as the growth of makrosperulites no longer occurs by the time this process begins. On request this system can also be used for MDO (Machine Direction Orientation).
Advantage Aqua Cooled Extrusion – ACE
The optimal mono and biaxial orientation of thermoplastic polymers follows the same basic physical laws. Decades of research and development by Plamex led to mature aggregates tailored to each step of the process and specific raw material requirements.
Process- and Line Description
Biax-fields of application
Related fields of application
Besides extruders, the blown film dies are the heart of each blown film extrusion line. Based on heavily experienced die experts and equipment with appropriate CNC – machine tools, Plamex is known as a reliable and innovative supplier.
In order to meet all demands of their customers, a variety of options are available: Mono and multilayer, conventional-vertical, Pancake–stackable horizontal, conical.
The selection of the right steel, coating and the best finish of the surfaces in contact with the melt are preconditions for the quality of the complete die head.
The specific Plamex design is distinguished by:
Special tubular tools
Special tubular tools for circumferential coating of woven structures e.g. the manufacturing of polyurethane coated polyester-based woven tube, which serves to re-seal corroded pipes in the ground. For this special application Plamex developed and delivered large caliber coating dies up to a diameter of 600mm. Larger diameters are available upon request.