OPPs

Oriented polypropylene film (OPP) may be classified as heat-set and non-heat-set, blown and tentered, coextmded and coated. Orientation improves the cold-temperature resistance and other physical properties. Heat-set biaxially oriented polypropylene film (BOPP) is the most widely used protective packagiag film ia the United States. It is used to wrap bakery products, as lamination pHes for potato and com chips, and for pastas and numerous other flexible pouch and wrapping appHcations. Nonheat-set OPP is used as a sparkling, transparent shrink-film overwrap for cartons of candy. 

OPP producers have expanded the core, creating a foam stmcture with lower density, greater opacity, and a stiffer, more paper-Hke feel. Vacuum metallisation increases opacity and water-vapor barrier properties. 

Catalog of OPP Publications and Other Information Media, EPA 730-B-94-011, Mat. 1994,105 pp available from Communications Branch, Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington, D.C. 

The purpose of the reaetor design is to aequire the optimum reaetor size. However, the ideal optimum reaetor size (V/F o)opp obtained by integrating the optimum temperature profile. That is. 

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