Extensible and semi-extensible sack kraft
High-stretch kraft for impeller and air-packer filling lines.
Request a quoteExtensible kraft is microcreped on the paper machine so the sheet can absorb elongation before it breaks. The property that matters is tensile energy absorption: the area under the stress–strain curve, i.e. how much work the sheet takes before rupture.
On a cement line filling at 1,800 sacks per hour, moving from standard to semi-extensible kraft typically removes the majority of burst-at-spout losses without changing the bag format or the machine settings.
Technical specification
Applications
- Cement and dry-mortar multiwall sacks
- Air-packer and impeller filling lines
- Chemical and fertiliser sacks
- Heavy-duty industrial packaging
Converter questions
What is the difference between extensible and standard sack kraft?
Standard sack kraft stretches around 2–2.5% in the machine direction. Semi-extensible kraft is creped during manufacture to reach 4–7%, which multiplies the energy the sheet absorbs before rupture. The trade-off is a higher price per tonne and slightly different runnability on the tuber.
Does extensible kraft need machine changes?
Usually not. Tension on the tuber may need reducing because the sheet elongates more, but the bag format, glue system and bottomer settings normally stay as they are.