| 摘要 |
<p>Films of biaxially oriented polypropylene have a heat-weldable coating consisting essentially of an interpolymer of (a) 5-15% by wt. of a mono-ethylenically unsatd. acid chosen from methacrylic acid and its mixts. with acrylic acid, (b) 50-85% of vinylidene chloride and (c) 5-45% of an alkyl acylate selected from Me, Et, Bu, iso-Bu and octyl acylates. It may also contain 0.1-1.0% by wt. of an anti-adhesive agent insoluble in water and consisting of finely divided particles measuring 1-5 mu. This is a finely divided wax or a material such as talc, silica, clay, mica or a PVC resin. The compsns. enable films to be heat-welded over a wider temp. range and at a lower min. temp., ad also increase the resistance of the films to the transfer of gases. The coated films have excellent optical properties. Interpolymers contg. 75-85% vinylidene chloride give films having sufficiently low viscosity to permit their use in automatic packaging machines.</p> |
