SML has developed and installed a new laminating line that is capable of downgauging the coating layer to a previously unobtainable extent using the so-called “DoubleCoat” process. “DoubleCoat”, for which a patent is pending, has been integrated into the proven FlexPack extrusion coating line thereby enlarging considerably the attainable range of breathable products.
“DoubleCoat” combines extrusion coating with hot melt lamination and thus facilitates coating thickness minimisation. For example, a minimum coating layer thickness of 7µm can be achieved using TPE on a PP nonwoven. This corresponds with roughly a mere quarter of the current average for such coatings and results in enormous material savings. Excellent product quality is guaranteed and even with thin coating layers adhesion to the substrate is perfect and no pinholes occur.
Another exciting feature of the process is enhanced product breathability. The coating thickness has a significant effect on the water vapour transmission rate (WVTR), as a thinner layer results in a reduction in water vapour flow resistance. Consequently, standard product breathability can be increased several times over. A further advantage offered by the new process is a reduction in the melt temperature to a minimum. This has a very positive effect on the mechanical characteristics of the coating because the material is subject to less stress during extrusion.
The advantages of the “DoubleCoat” process at a glance:
• Reduced coating layer thickness
• Material savings and hence lower costs
• Strong adhesion
• Improved breathability
• High water column
• Enhanced mechanical properties
The “DoubleCoat” process provides fresh possibilities for enhanced product properties and lower production costs with regard to a variety of applications. These include medical products such as surgical drapes, which are highly breathable, flexible and serve as an effective barrier against viruses and bacteria. The process could also be used for protective clothing such as disposal overalls, or in view of its soft touch, stretchability and high breathability, for hygiene products. Moreover traditional construction industry products such as roofing underlay can benefit to an equal extent from this new method.
Interested customers will soon be able to see the outstanding performance of SML’s FlexPack extrusion coating line with the “DoubleCoat” process for themselves, as a production scale pilot plant will be available for trials from April 2016.
