Unoriented polypropylene films
2024-03-26 16:05Unoriented polypropylene films can be produced by casting or blown film processes. Chill roll casting and tubular water quenching are commonly used. Conventional air quenching, widely used for polyethylene, produces brittle films with poor clarity in polypropylene; however, newer polypropylene resins and copolymers developed for air-quenched processes can provide economical alternatives to polyethylene. The tubular water-quench process is commonly used to produce monolayer film Unoriented films have a very soft hand and are easily heat sealed. They exhibit good heat stability, low flexural moduli, excellent puncture resistance,excellent impact strength, and low moisture permeability but provide only poor barriers to gases, such as oxygen and carbon dioxide, some perfumes, and oil such as peppermint oil. Clarity of unoriented random copolymer film is moderate and is affected by processing conditions. Because its physical properties are balanced, unoriented film is easier to process on bag-making equipment than cast-oriented film, and slitting and sealing is easier in the transverse direction. Applications include packaging for shirts, hosiery, bread, and produce, used as a strength and barrier layer in disposable diapers, and used in electrical capacitors.