Why are there different types and which applicatio

Of the three films used, biaxially oriented polypropylene films, called OPP, are the most economical. It offers good gloss, or matte appearance depending upon the type. It does not absorb water.

Polyethylene terephthalate, called PET, offer high strength and stiffness for books, menus, identification cards and such. PET has the highest melting temperature of the three main films.

Nylon-6 is a unique polymer. Oriented nylon can absorb up to 6% moisture by weight and swell of expands. Paper also expands with changes in moisture so that both materials move together. As a result curl of the laminate is minimal. Most laminations of a paper to an impervious plastic material such as OPP or PET exhibit curl depending upon the moisture content of the paper. Paperback books are the largest application for the nylon thermal laminating films because the book will not curl open with humidity changes.