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DuPont™ Surlyn®

Flexible DuPont™ Surlyn® bag in a rigid outer-bottle

Case Study Image

Application Description

Düsseldorf, April 21, 2005 - - The 'bottle in the bottle' is an innovative and intelligent packaging concept for cosmetics and pharmacy products, developed by the German company Gaplast GmbH and using DuPont packaging resins. The outer-bottle, made from a stiff thermoplastic, such as PET, encloses a flexible bag of DuPont™ Surlyn®. Thanks to the minimal adhesion between the Surlyn® and the exterior material, the inner-bag easily detaches itself from the bottle and evenly contracts during extraction of the contents. At the same time, a specially designed applicator ensures that the bottle contents do not come into contact with the ambient air (so-called 'AirLEssMOTION') and enables the germ-free dispensing of the product.

The bottle is produced using coextrusion blow molding, whilst a patented process helps attach the inner-bag of Surlyn® to the top and bottom of the outer-bottle. This ensures that the bag remains stretched in the vertical when emptied, and contracts only in the horizontal. Supported by the dispensing appliance - a so-called airless pump - a virtually complete emptying of the bottle is enabled. Depending on the shape and size of the bottle, residual contents range from one, to a maximum of four, percent. 

Packaging manufacturers also benefit from a high degree of design freedom. The bottle can be individually shaped, and maintains its silhouette regardless of the shape of the inner-bag. Last but not least, thanks to the high transparency of the exterior material and of Surlyn®, the contents are presented in a pleasingly aesthetic manner - they appear to float within the bottle.

A key benefit of 'AirLEssMOTION' bottles is the ability to both fill and dispense without exposure to germs. This means that considerably fewer preservatives need to be added than with products in traditional packaging. In addition, this kind of packaging ensures product purity and stability. This in turn helps meet new cosmetics guidelines requiring that the period after opening (PAO) - in other words, the time period that the consumer may use the product without any loss of quality - be stated on the product.

Surlyn® packaging resin was selected as the material for the inner-bag due to its high transparency and chemical resistance, as well as its limited adhesion to the outer-bottle. The film extrusion grades Surlyn® 1650 E and 1652 are used here respectively, as they both provide excellent processing behaviour during extrusion blow molding. In order to optimise barrier properties, the inner-bag may consist of several layers. Materials used in such a case will depend on customer requirements.

Gaplast GmbH was formed in 1969 as part of the Geiger Group, and has operated independently under the name of Gaplast since 1976. The company develops and produces plastics systems for pharmaceutical, medical and cosmetics industry. It provides customers a complete service from the original concept, through production, assembly, packaging, filling to final packaging. In 2003, Gaplast launched the brand 'Lemotion' for its range of cosmetics packaging.

Photo Caption

Outside rigid, inside flexible - this dual-walled bottle with specially-designed applicator enables the germ-free dispensing of cosmetics and pharmaceuticals. As the inner-bag, made of DuPont™ Surlyn®, has only limited adhesion to the rigid outer-bottle, it evenly contracts during dispensing. The highly flexible Surlyn® thus enables a virtually complete extraction of the contents.