| 摘要 |
<p>Multiple layer films, and novel polymer compositions are disclosed for use in packaging sterile medical products and shelf stable foods. The films include at least two layers (12, 14) of modified polypropylene-based compositions, and optionally a third layer of polypropylene-based composition. The two layers (12, 14) of the film comprise polypropylene polymers having melting point temperatures, differing by at least 3 DEG C, with corresponding ethylene contents disparate by at least 1 weight percent ethylene. In 2-layer films, the compositions include ethylene butene-1 copolymer in both layers, and optionally an elastomer in either or both layers. Three and four layer films are also disclosed wherein outer polypropylene based layers protect the inner layers, as of the two layer composition, from bonding to corresponding portions of adjacent like layers. The films can be fabricated into packages formed as by heat sealing, a covered tray type package being shown in Fig. 6.</p> |
