Biaxially Oriented Polypropylene or BOPP as it is called is basically a plastic film made out of polypropylene. It is stretched in both the machine and cross directions during manufacturing. BOPP films have gained popularity in the world due to some of their special characteristics. They act as a good barrier against water vapor and are resistant to grease and oil. They do not shrink because of changes in the environment, and are also resistant to moisture. They are dimensionally stable and have a low electrostatic charge. In fact, the BOPP films are also recyclable.
Whenever you buy a new
household device, it is always packed in a tightly sealed plastic wrap. Even
small items like soaps and shampoo bottles come with a sealed plastic film
around them. Have you ever wondered how this is done? This is all thanks to
innovation in the plastic films industry. Many variations of the BOPP film are now
produced in the market, one of which is the heat sealable BOPP film. Its
excellent sealing characteristic is a result of the co-extrusion process during
manufacturing. This film can be one or two-side heat sealable. In a one-side
heat sealable BOPP film, the non-sealable side is generally used for printing
and laminating. It used for general purpose packaging for food items, tea,
toffees, tooth brushes and cassette tapes. The BOPP films have good heat
sealing strength and a smooth surface, and are highly transparent. Heat sealing
is usually done at a temperature of around 130 degrees Celsius. The BOPP
structure is also sometimes modified in order to lower the Seal Initial
Temperature (SIT). This improves the sealing performance and allows high speed
packaging, especially useful for temperature sensitive products like snacks and
ice-creams.
There are different
kinds of heat sealing devices available, the basic principle being to heat up
two separate layers of plastic film together till the seal is made.