— APPLICATION
LDPE and PP for shrink film, bags and heavy-duty sacks
An LDPE shrink film grade, a sack film and a carrier bag share one job: carry weight without tearing, puncturing or stretching out of shape. A shrink hood holds a pallet of bottles together on a lorry. A 25 kg sack of fertiliser is dropped, stacked and left outside for a season. This page covers how melt strength, toughness and stiffness decide the grade, and shows the grades we can supply.
— REQUIREMENTS
What a load-carrying film has to do
Shrink film has to shrink evenly in the tunnel and then keep the load tight. The shrink force left in the cooled film matters as much as the shrink itself.
A heavy-duty sack is dropped full, so it needs dart impact strength. Sharp granules and pallet corners test its puncture resistance, and the top seal has to hold the full weight. Stacked sacks and hooded pallets stay under load for months. Film that creeps lets the stack lean. Liners and carrier bags need tear strength at the lowest gauge the customer will accept.
— SELECTION
Choosing heavy duty sack film and shrink grades
Low-flow LDPE is the base. Its long-chain branches give the melt strength that keeps the bubble stable and freezes orientation into the film, which is what makes it shrink when reheated. Fractional-melt grades, below 1 g/10 min at 190 °C/2.16 kg, give the most shrink and toughness. Higher-flow LDPE gives better optics and easier running for thinner film.
For sacks and liners, LDPE is usually blended with linear low density polyethylene for puncture and dart impact. HDPE adds stiffness, so a thinner sack still runs on the filling machine. Polypropylene impact copolymer makes heavy-duty film with good puncture and tear resistance. PP random copolymer can be made into clear shrink film on double-bubble lines.
Slip and antiblock help bags open and sacks separate. On a pallet you want the opposite: a slippery sack slides off the stack. Woven polypropylene sacks are covered on raffia, tapes and strapping.
— GRADES
Grades we can supply
Compare melt flow at the same test conditions before you compare shrink or toughness.
LDPE
KeyForm
·
Velogy
LDPE
KeyForm L0400
LDPE
Non-additivated low-density polyethylene with high melt strength for blown-film extrusion and good bubble stability.
Blown film extrusion
Film extrusion
Industries
Flexible packaging
KeyForm
·
Velogy
LDPE
KeyForm L0401
LDPE
KeyForm L0401 is a non-additivated low-density polyethylene, for blown-film extrusion. Its high melt strength supports bubble stability.
Film extrusion
Blown film extrusion
Extrusion blow moulding
Industries
Flexible packaging
Rigid packaging
KeyForm
·
Velogy
LDPE
KeyForm L0600
LDPE
KeyForm L0600 is a non-additivated low-density polyethylene, supplied as pellets. Its good melt strength supports bubble stability during blown-film extrusion.
Film extrusion
Blown film extrusion
Industries
Flexible packaging
— NEED HELP CHOOSING?
Not sure which grade fits?
Send us the film type, gauge, blow-up ratio and the load the film has to carry.
— PROCESSING
Blown film and form-fill-seal
Almost all of this film is blown. The blow-up ratio sets the balance between lengthways and crossways shrink, so tell us the ratio as well as the gauge. Heavy-duty sacks are often made on form-fill-seal (FFS) lines from tubular film, where stiffness and seal strength set the filling speed and the seal has to close through product dust.
Blown film extrusion
— DOCUMENTATION
Recycled content and food contact
Shrink hoods, sacks and pallet wraps are packaging under the Packaging and Packaging Waste Regulation (EU) 2025/40. From 2030 at the earliest, plastic packaging that is not contact-sensitive must contain at least 35% post-consumer recycled content, averaged per plant and year (Article 7). Packaging for dangerous goods is exempt. Bags and liners that touch food need a declaration of compliance for the grade under Regulation (EU) No 10/2011, which we pass on from the producer.
— PRODUCERS
Producers for this application
Brands for this application
— FAQ
Common questions
What should I look for in an FFS film grade?
Can I use LDPE for stretch hood film?
Can these grades be blended with recycled polyethylene?
— RELATED
