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BPS Blown Prestretch Film Lines

Macro's BPS Series of blown prestretch film lines provides processors with a single line solution for the production of high quality prestretch film rolls.

The BPS Blown Prestretch Film Line Advantage

• Single process from resin to sellable rolls
• Inexpensive resins
• No trim, no reclaim, no waste
• Soft, lightweight rolls
• Very thin film (6-7 microns)
• 2-ply film
• Blown film strength
• Thick edges for extra resilience
• Excellent gauge
• Tacky
• Low tower height

Why Prestretched Film?

Blown film LLDPE grades exhibit better puncture and tear resistance than cast PE grades; however, stretch film produced using blown PE grades have higher yield points than cast PE grades. This means stretch film produced via the blown process requires more energy or strength during prestretching in pallet wrap applications; a limitation steering many end users away from blown stretch films.  Macro’s BPS line removes this limitation by prestretching the film before winding. This creates a film with the superior mechanical properties of a blown process without the high energy stretch requirements of regular blown film stretch films. 

The BPS Film Advantage

Macro’s BPS line creates soft, lightweight prestretched rolls that are easy to handle and unwind. The rolls are suitable for machine and hand wrapping applications.  The film is a 2-ply structure that provides an extra layer of strength; if there is a defect in one ply the other will cover the load. The BPS film is very thin; however, the edges are 40-80% thicker to provide additional strength and minimize the possibility of tearing when wrapping.  The edge thickness can be adjusted. The film is immediately tacky without the need for additional conditioning or special storage.

The BPS Process Advantage

Macro's patented process is based on a single-layer blown film method that is much less complicated than typically used cast coextrusion processes. It consists of a single extruder that processes a mixture of butene-based LLDPE and LDPE with direct injection of tackifier into the extruder barrel. These resins are much less expensive than the octene-based resins that are used in traditional prestretch film production. 

The bubble is formed using a Macro single-layer die, which provides gauge better than +/- 7%. Cooling and stabilizing of the bubble is done with a D10 dual lip air ring combined with a curved-arm stabilizing cage. The bubble is collapsed at a height of only 5.5 m where it is intentionally blocked to create a 2-ply film. The film is then slit either 2-up or 4-up and sent to the stretching unit where it is thinned to 6 or 7 microns. No trims are taken, and no scrap is created in the process.  This combination of very thin film, created with inexpensive resins, and no trim or scrap generates significant savings to
the processor. Not only does the processor use less resin, which is also less expensive, there is also no need for costly reclaim and conveying systems to collect trims.

The stretching unit provides the appropriate stretch to the film through a series of independently driven rollers, which are also independently temperature controlled. This allows for precise control of the prestretch; minimizing the possibility of the film tearing during wrapping.

The film is wound on a fully automatic turret winder, which is specially designed for winding soft rolls. Soft rolls are prepared by reducing the winding tension and deliberately entrapping air between the winding layers. The soft rolls provide the advantage of being more resilient than hard rolls; the edges will not damage if the roll is dropped. The softly wound rolls are also lightweight and require less force to unwind. The winder is capable of indexing every 15 seconds, depending on roll diameter requirements.  For the 4-ply setup, the line is fully automated to remove rolls and insert cores. 

The entire process is very simple. Line startup is only about 10 minutes.

For more information about the BPS line contact us.