Gneuss: Top quality PET strapping tape efficiently made from bottle flake

Interstrap B.V. in Heerlen, Holland is extremely satisfied with the performance of their fully automatic rotary filtration system RSFgenius and the Online Viscometer from Gneuss Kunststofftechnik GmbH (www.gneuss.com). This company has been using these systems for the processing of PET bottle flakes to strapping tape since mid 2007 and is delighted with the high product quality which is achieved and the short return on investment of the equipment.

PET Strapping tape replacement for steel strapping
Strapping tape made from PET is on the advance throughout the world as a replacement for steel strapping. For securing loads such as paper, cotton but also wood and building materials such as stones and bricks, PET strapping tapes have major advantages. Unlike steel strapping, PET strapping tapes have a high shock reserve for sudden loads and are at the same time sufficiently elastic, that they can securely hold shrinkable loads. They are easier to secure, lighter and are immune to weather as they do not rust (and can not stain the product) and have no sharp edges which could cause injury when they are opened.

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Interstrap is a specialist in this growing market segment. In addition to other products, Interstrap manufactures PET strapping tape with widths of between 8 and 16 mm. Interstrap belongs to the Orgapack Strapex Group, a group of companies specialised in packaging and logistics. Interstrap is a member of the ITW group, the larges manufacturer of strapping in the world.

For the manufacture of strapping tapes (which are generally coloured a shade of green) this company exclusively uses post consumer bottle flake which is available at a low cost. When using this material, it is imperative that the extrusion line runs without disturbances in spite of the varying contamination load in the form of sand, paper, adhesives and foreign polymers in the product.

The continuous filtration of the polyester melt in the extrusion line for strapping tapes is ensured by the RSFgenius from Gneuss Kunststofftechnik. In spite of the frequently high contamination level of the PET flakes, only one filtration system is used. There is no need for a pre-filter or downstream filter.

The Rotary Filtration System RSFgenius was purchased to replace a double piston screen changer which had proven to be unsuitable for this application with a high contamination level due to the disturbances created during the frequent screen changes.

Ideal Filtration System for PET Bottle Flakes
The RSFgenius is equipped with a unique, integrated sequential high pressure back flushing system which achieves complete cleaning. Depending on the filtration fineness, up to 400 uses can be obtained from the screenpacks, which typically means screen pack changes every 2 months. The rheologically optimised melt flow channel design completely avoids the creation of degraded particles. The residence time of the polymer in the screenchanger is extremely short and the residence time spectrum extremely narrow. Thanks to the completely encapsulated design, there is no contact between the polymer and oxygen or moisture. The system is above all characterised by its extremely economic performance and its user friendliness in terms of minimal operator attention and maintenance. Due to all these advantages, the RSFgenius has become established worldwide as the ideal polymer melt filtration system for the processing of PET bottle flakes, whether in the manufacture of bottles, fibres, strapping tape, fibres (nonwovens and filament yarn) sheet and film.

Reliable Monitoring of the Melt Viscosity
In addition to the Rotary Filtration System, Interstrap also uses the Gneuss Online Viscometer. This unit continuously monitors the melt viscosity which is the key parameter for the tensile strength and therefore for the quality classification of the strapping tape. Variations in the drying process and - more commonly - variations in the properties of the bottle flake are immediately identified so that action can be taken as early as possible.

Photo: Online-Viscometer and Filtrationsystem RSFgenius in Interstrap production line

Gneuß Kunststofftechnik GmbH, Bad Oeynhausen, Germany

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