ALLVAC and its sister company BREVAC jointly develop and produce coextruded blown films. The multi-layer film solutions which are used for special requirements and can be further processed on all common machines offer special advantages with regard to variable strength, flexibility and resilience, due to blow extrusion.
In blow extrusion, the melt is firstly pressed through a device equipped with a ring die. The resulting melt hose is inflated with air and cooled from the outside and inside by cooling air jet. The column formed during this process is now in a stable position. As soon as the melt mixture has cooled below the melting temperature range, the hose is joined by two opposite sliding rollers. Subsequently, the flattened hose is transported from guide rollers to a cutting device, assembled into individual webs and wound onto rollers. ALLVAC uses this process to produce films with up to 18 layers which are placed on top of each other in the blow head. Water-cooled blown film extrusion achieves very high cooling rates resulting in soft, elastic films with an almost amorphous molecular structure.
Blow extrusion layer by layer
Our composite films produced by means of blow extrusion consist of several layers which combine the positive properties of different materials in one film. Each layer performs an important function: The PA layers are the crucial factor for the mechanical strength of the packaging. Working as a functional barrier layer, EVOH seals in aroma and prevents the penetration of oxygen, thereby extending the shelf life of your product. The PE layer on the inside of the packaging serves as a sealing medium and is the crucial factor for providing airtight seams and a proper skin sealing. It serves as a moisture barrier and, although it stops your product from drying out, it also prevents the uncontrolled absorption of moisture. The tie layer between PA and PE has the task of reliably tying them together so as to prevent delamination, even at high or varying temperatures. These specific characteristics make these films particularly suitable for the food industry.
