| 摘要 |
<p>A method of reducing the gas-permeability of a substrate comprises applying a barrier coating of a first polymer to the substrate, and then applying a protective coating of a second polymer to the barrier-coated substrate. The substrate may be a film for shrink-wrapping, a bottle, gasoline tank or paint can, or a preform which is expanded by blow moulding, after applying the coatings, to become oriented. The barrier coating may be polyvinyl alcohol, ethylene-polyvinyl alcohol copolymer or polyvinylidene chloride, of thickness 1-5 Ám. The protective coating may be a solution of a second polymer of molecular weight 5,000 - 50,000.</p> |
