Higher tape tenacity and indexed micro perforation

BSW’s processing technology for woven PP bags

BSW Machinery’s AD proTex LS bag

The new Light and Strong technology (LS) will allow bag producers to reduce their material usage. Critical areas of the bags are made stronger compared to older technologies. The overall thickness and weight of the bag material can be reduced while maintaining current strength. For cement bags 80 grams a bag are quite common.

Tape strength directly influences the weight of a woven PP bag and meets certain mechanical bag requirements like impact resistance at bag drop. For a wide range of bags an increase of strength can directly be transferred into a lighter bag. As the raw material dominates up to 80% of the cost of a bag, every increase in strength can reduce the production cost for a converter. Moreover, less material directly results in less energy for a bag needed in extrusion.

Up to now higher strength values were compromising the elasticity or vice versa. Now, the new processing technology implemented on BSW’s tape extrusion line tiraTex has broken down this old barrier. Even with standard PP grades which are commonly used in the industry, tenacity values of 7 g/den can be achieved with elongation at break values ranging between 25% and 30%. The processing characteristics provide the best results even at highest outputs and production speeds of 500 metres a minute or more.

Micro- or nano perforation provides the needed holes for bag ventilation during the filing process. However, each hole weakens the tapes which define the strength of the bag – especially the feather edges are vulnerable when handling or dropping the bags. The new LS concept protects crucial edges and other areas through indexed perforation. The perforation is disengaged whenever vital sections of bag material are passing through the bag conversion machine. Synchronization ensures that the unperforated areas are matching to the print on the bag and are placed such that in the final bag the critical zones are built from unperforated material.

Packaging South Asia is the cooperating media partner for drupa 2016 which is scheduled to be held from 31 May to 10 June at Dusseldorf, Germany