| 摘要 |
<p>Transparent impact resistant sheets of polyolefin materials made by lamination of thinner films (1.6 mm. thick) of (biaxially oriented) material at pressures of 3.5-141, pref. 7-70 kg./cm.2 at a temperature (slightly) below the crystalline melting point of the material. Pref. successive films are laid up with the principal axis of orientation normal to one another. Lamination of extrusion blown and oriented films allows thick sheets to be made with a higher degree of transparency and toughness than is possible by moulding or extrusion of material directly to the required thickness.</p> |
