Coating & Laminating
New features of tunable feedblock for extrusion coating N
ordson Corporation has increased the versatility of its most advanced coextrusion feedblock for multi-layer
extrusion coating and cast film. It now provides the option of a selector spool that can be used to vary the sequence of the layers. The new Extrusion Dies Industries Ultraflow V-TS feedblock offers the greatest potential benefit for applications that include layers of costly functional polymers, such as barrier resins for food packaging, because it helps to control the consumption of such materials. In the Ultraflow V-TS feedblock, the
selector spool can change the sequencing of all layer materials, including the polymer in the core layer, resulting in maximum product-structure versatility. By changing selector spools, it is possible to change the sequence of layer materials without having to block off channels or disassemble the feedblock. This provides versatility for processors who periodically switch material from core to skin layer, for example, or from the inside skin to the outside skin. In a five- layer ‘a-b-c-b-a’ structure, one possible variation among many is ‘a-c-b-c-a’.
The use of a selector spool for
layer sequencing is particularly important for extrusion coating and cast film processes, in which the die is mounted vertically for downward extrusion onto a chill roll or into a coating nip. In such a configuration, the extruders can feed material into the system at the same elevation as the spool housing. This simplifies and streamlines the melt pipes that deliver molten polymer to the feedblock. In addition to this, a selector spool allows the layer sequence to be pre- arranged upstream of the combining point, providing a safe method for making adjustments without removing the feedblock from the production line. The new V-TS feedblock expands upon the
recently introduced new-generation design, the Ultraflow V-T, which enables extrusion coating processors to fine-tune individual layers as well as accommodate changes in layer ratio while the line is still running. The ability to refine the layer uniformity ‘on the fly’ allows the processor to minimise consumption of their most expensive resin
by reducing this layer’s average thickness due to the tighter layer tolerances. One of the key devices in the Ultraflow V-
T feedblock is a pair of ‘combining planes’ (located where the outer-layer melt streams join the core layer in the central flow channel) that fine-tune the overall structure by adjusting the gaps at the point of layer combination. The other device is a pair of ‘profiling actuators’ (located opposite the combining planes) within which are mounted interchangeable ‘profile bars’ that fine-tune the thickness uniformity of the individual layers. By rotating the actuators, it is possible to achieve a wide array of results without needing to stop production to re- machine profiling inserts.
www.nordson.com
www.convertermag.co.uk
July/August 2017
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