Plastic nettings for improved product performance

Paul Boughton

In many applications, product strength specifications are met by increasing the weight or thickness of the substrates. The use of Conwed plastic netting structures in product construction can help save material, improve physical product performance and increase line speed.

There are different methods to use Conwed nettings in various manufacturing processes.

In the production of non-wovens, improved strength can be obtained by incorporating Conwed nettings. This involves much less operating work than might be expected.

The non-woven is produced via a dry-laid, a wet-laid, a spunbond or a melt blown process. Plastic nettings can be introduced in the web formation step during the nonwoven production. Then the web of  fibres, together with the netting, are bonded to form the final non-woven composite.

Several processes are available for bonding various types of non-wovens:

* Chemical bonding: the composite is generated by dipping the complete composite into bonding agent and drying it afterwards.

* Thermal bonding: there are several technologies, but they feature in common that heat, time and pressure are necessary for an outstanding adhesion. Proved in practice are the technologies of using a flatbed laminating machine or heated calendar rollers.

* Mechanical bonding: hydro-entanglement and needlepunching are techniques to intertwine the non-woven fibres and the netting to form a strong non-woven composite.

Some examples of these applications are cleaning wipes, roofing underlayment materials, pleated air cabin filters, etc.

Extrusion coating or extrusion lamination is used e.g. to produce foil-based roofing underlayment products, packaging materials or composites for technical applications. A poly-olefin film is extruded directly onto the substrate to achieve an impervious surface and to avoid an additional adhesive layer in the product construction. When plastic nettings are applied between the substrate layer and the extruded film layer, tensile strength and tear strength can be increased significantly and the dimensional stability of the product is secured.

Lamination

Laminates are materials which are constructed by uniting two or more layers, either similar or different materials: plastic nettings, plastic films, nonwovens, paper. For lamination with Conwed plastic netting, basically three different methods are applicable:

* Thermal lamination: one of the two materials of the laminate is melted to the other material under increased temperature and pressure, which results in a strong permanent bond.

* Ultrasonic lamination: similar polymers are combined using mechanical vibration and pressure. The substrates are threaded through a well-precised gap and welded together by means of high frequency vibration and pressure.

* Adhesive lamination: in case none of the fabrics of the composite structure develop adhesive properties or when the process conditions (low temperature or pressure) are limited to obtain a good bond, an adhesive can be used to bond the layers together. Depending on the final application, wet or dry lamination processes are used. Conwed can also produce Thermanet nettings with a built-in adhesive. This is a patented co-extrusion technique. Via this way no separate adhesive needs to be applied because these nettings can be easily laminated with thermal heating to the substrate that needs reinforcement.

Tailor-made solutions

Conwed plastic nettings can be produced accordingly customer specifications, varying in mesh size, shape, thickness, weight and tensile strength. So, before you assume we are no solution for your project, challenge us!

Conweb Plastics is based in Genk, Belgium. www.conwedplastics.com

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