Coextrusion Automates Bag-in-Bottle Production

Innovative bag-in-the-bottle technology from Gaplast GmbH of Saulgrub-Altenau, Germany, uses coextrusion blow molding to produce a thin bag made of ionomer inside a PP bottle.

Innovative bag-in-the-bottle technology from Gaplast GmbH of Saulgrub-Altenau, Germany, uses coextrusion blow molding to produce a thin bag made of ionomer inside a PP bottle. The two incompatible materials separate easily after molding, leaving a flexible bag joined at the neck with a stiffer bottle. This concept eliminates labor-intensive assembly of four separately produced components. The 1-liter disinfectant spray bottle—winner of a recent 2008 DuPont Packaging Award—is the largest size bottle using this approach. It was made on a BM 206 DL dual-station coex tandem shuttle machine from Bekum (U.S. office in Williamston, Mich). The Bekum unit has four extrusion heads and six extruders running twin four-cavity molds. The extrusion head has a spiral distributor for the PP bottle resin, while a side-fed die head with a heart-shaped curved tube introduces the inside bag layer (0.1 to 0.2 mm of Surlyn ionomer from DuPont Packaging & Industrial Polymers, Wilmington, Del.). The machine has bobbing extruders to optimize control of the tubing, and a quick-change feature for the extrusion head. The machine can run up to six layers; three for the outer bottle and three for the inner bag. A post-molding operation in a separate machine partially delaminates the bag from the PP, and vent holes are incorporated without piercing the bag. A co-molded seal connects the bag and 1-mm-thick bottle at the bottom. Gaplast is targeting other cosmetics and pharmaceutical applications in Europe. +49-8845-741326 • www.gaplast.de (517) 655-4331 • www.bekumamerica.com (800) 438-7225 • www.dupont.com

DuPont Co., Packaging &
Industrial Polymers
Barley Mills Plaza BMP 22-1157 Wilmington, DE 19880-0022
Phone (302) 999-5912 Fax (304) 863-2779 

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