The weldability of plane foil as affected by linear polyethylene
1991
Stark, L. (Tejgazdasagi Kiserleti Intezet (Hungary))
The aim of the study was to establish the right proportion of the mixture of low density polyethylen and linear polyethylene in order to improve the weldability of the foil. The samples were prepared from low density polyethylene by the addition of 0, 30, 40 and 50 o/o linear polyethylene, resp. (marked "0", "30", "40", "50" mixture). The foil was prepared on a two-slit Windmuller extruder. The flow number of the linear polyethylene was 14 g/10 min (190 C degrees, 21.6 kg) with a density of 0.834 g/cm3. The flow number of low density polyethylene was 0.9/10 min (190 C degrees, 2.16 kg) with a density of 0.921 g/cm3. The samples were used to make pouches at various x temperatures on Type HM-3 (Nagema) packaging machine. The optimum welding temperature zone was in longitudinal direction for every composition 220-270 C degrees. In transversal direction for sample "0" 200-260 C degrees, for sample "30" 200-270 C degrees, for samples "40" and "50" 210-280 C degrees. The stability of the transversal seam was higher by 50 o/o for sample "30", by 25 o/o for sample "40" and by 60 o/o for sample "50" than that of sample "0". The stability of the longitudinal seams was not much affected by the composition. It is evident that the weldability of low density polyethylene was improved by the addition of linear polyethylene, at the same time the proportion of faulty seams was lower (with sample "0" the proportion was 0.2 o/o and with all the foils containing linear polyethylene, 0.1 o/o).
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