Brampton Engineering ships first 11-layer blown-film line

-- Converting Magazine, 5/8/2008

In what is reportedly a world first, Brampton, Ontario, Canada-based Brampton Engineering says it has shipped an 11-layer blown-film line from its plant to a proprietary customer.

Thirteen years ago, during the 1995 TAPPI Polymers, Laminations and Coatings Conference, BE presented a paper that provided theoretical justification for the possibility that one day the market would request an 11-layer blown-film line. 

The company's SCD® multilayer, streamlined-coextrusion die became the first successfully commercial 7-layer die and later led the way to the first 8-, 9-, 10- and now, 11-layer blown-film lines, the supplier says. BE has shipped dozens of 7- to 11-layer SCD® systems.

As the number of layers goes up, the die-extruder arrangement becomes increasingly constricted. Eleven extruders radially around the SCD® die require longer adaptors and result in a very crowded hot section. Ideally, for barrier film coextrusion the adaptors should be short and straight. 

BE's solution was to design piggybacked extruders, or two extruders with one mounted on top of another. The design of the SCD® provides a good marriage for piggybacked extruders because the extruder center-line heights are different for each layer, BE says. The configuration for the 11-layer line then became two piggybacked extruders plus seven normal extruders, creating a radial extruder configuration similar to a 9-layer line but with two of the extruders being doubles.