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what is Biaxially Oriented Polypropylene Film?

Mal Baxter
Mal Baxter

Biaxially oriented polypropylene film, or BOPP film, is often seen in small or large rolls of clear plastic sheets used in packaging and wrapping. This popular, widely adopted stretched polypropylene performs duty across a range of industries and products. Its unique properties include shrinkage, transparency, and sealability, all of which permit numerous applications in industrial, commercial, and household use. Common products made from this material include Mylar® and shrink wrap.

This film is manufactured with many different dimensions and treatments for end products from stationery to snack food bags. It can also be metalized for additional uses and applications. On smaller scales, it is used as wrapping for flower sleeves, pressure sensitive tape, and even clear bags.

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Woman posing

The clarity of this film is a result of orienting the molecular structure of polypropylene in two uniform directions, which also enhances molecular strength and self-adhesing while minimizing elongation properties. Several manufacturing processes result in flexible plastic sheets of various sizes, thicknesses, and finishes. With higher tensile strength, the film provides an attractive and stable medium in which to hold products for shipping as well as crisp, clean packaging for products. The film also provides an effective barrier against foreign particles; this trait, along with being waterproof, makes it a conventional packaging choice for food-grade products.

Another advantage of biaxially oriented polypropylene film is its high-seal strength, even with low seal pressure. Its symmetrical polymer structure affords a higher melting point for expedient machine processing. A low initiation temperature and wide window for sealing make it a versatile material for inconsistent handling with minimal damage. An additional characteristic of the film is its resistance to haze that can result from evaporation and humidity.

By providing a thermal resistant barrier, biaxially oriented polypropylene film is heat-sealable. This allows it to perform as lamination in printing and gift wrapping, as well as wrapping for large-scale products on shipping pallets. These thermal-resistant properties enable faster performance when loaded in high-speed form, fill, and sealing (FFS) machines.

In addition to this characteristic, BOPP film possesses lower tackiness and easier jaw release than other types of packaging. As polypropylene carries a measure of health concern regarding toxic byproducts, the minimal amorphous fraction of biaxially oriented polypropylene film means reduced xylene extractables. That is, it is typically a non-toxic, non-adhesive film; it produces few irritants for inhalation or exposure.

Stable surface properties result from low blooming and low amorphous molecular weight or other additives. Manufactured via methods of extrusion, injection, and stretch blow molding, the material surface is given treatments to allow for application of inks and paint. This versatile, ubiquitous film has become a commonplace wrapping and packing product, performing many roles.

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