| 摘要 |
<p>Apparatus and method for fabricating films, especially films containing vinylidene chloride copolymer, wherein the process is susceptible of continued operation over an extended period of time greater than a few days. The process typically can operate for at least 2 weeks between shut downs for cleaning the die. The apparatus comprises a coextrusion feedblock in combination with an annular extrusion die having a crosshead mandrel, and means for conveying the exit stream from the feedblock to the die. The particular apparatus combination especially reduces the rate of carbon buildup in the extrusion apparatus during extrusion of VDC-copolymer, such that the extrusion process can be operated for a longer timebetween shutdowns for cleaning and maintenance of the die. The invention furtherincludes novel tubular films made with the apparatus and methods of the invention, and packages made from the films. In general, the method of the invention produces tubular films having more layers than the annular extrusion die has annular orifices.</p> |
