Sack kraft paper for bag converters
Mill-direct sack kraft reels for SOS, open-mouth and valve sack lines.
Request a quoteSack kraft is the long-fibre, high-porosity grade developed for sack and bag converting: it has to survive the forming shoulder, the bottomer and, in cement or chemical filling, a violent air-displacement shock at the filling spout. That is why it is specified by tensile energy absorption (TEA) and stretch rather than by tensile strength alone.
WeePaper supplies sack kraft in standard and semi-extensible grades from European mills, slit to the converter's reel width and delivered against a rolling call-off. Minimum order is 20 t per grade and width combination.
Technical specification
Applications
- Multiwall cement and mortar sacks
- SOS shopping and takeaway bags
- Open-mouth sacks for chemicals, feed and seed
- Valve sacks for powdered products
Converter questions
What is sack kraft paper?
Sack kraft is a long-fibre unbleached or bleached kraft grade made specifically for sack and bag production. Compared with ordinary kraft wrapping paper it has much higher tensile energy absorption, controlled stretch and a porous structure that lets air escape when the sack is filled at speed.
What grammage should a bag line run?
Most shopping-bag and takeaway lines run 70–90 g/m². Multiwall cement and chemical sacks typically use 70–100 g/m² per ply across two or three plies. Above 120 g/m² the grade is normally used as a single-ply heavy-duty sack or as a reinforcement layer.
Standard or extensible?
Standard sack kraft is enough for hand-filled and light mechanical filling. Where the sack is filled by an impeller or air-packer, semi-extensible kraft with 4–7% stretch absorbs the shock and cuts burst losses on the filling line.