| 摘要 |
<p>A biaxially oriented heat shrinkable polyolefin film comprises a layer of polypropylene-based resin containing microvoids, the microvoids being formed by stretching a web containing the beta-form of polypropylene, the film having a shrinkage after 10 minutes at 130‹C of at least 10% in at least one direction. Preferably a nucleating agent, such as an amide, is used to induce the formation of the beta-form of polypropylene. Preferably the film is formed by extrusion and is then stretched firstly along the extrusion direction and then transverse to the extrusion direction. The film may contain additional polyolefin layers, eg layers which are heat sealable, printable or glossy, and may have additives incorporated therein, eg. slip agents, antistatic agents, antiblock agents, stabilizers, UV absorbers or pigments.</p> |
