| 摘要 |
<p>Film or sheet of flexible thermoplastic material is characterised by at least a part of one surface presenting a series of ribs extending between two of its edges. The film or sheet pref. consists of polyethylene. The film or sheet is used in the manufacture of a container, such as an envelope, in such manner that the series of ribs define a tear path, which facilitates the opening of the sealed container.</p> |
