- February 28, 2006, David J. Bent David J. Bentley Jr., Contributing Editor
Providing practical information to the converting and packaging industries…
Effects Of Converting Operations On The Barrier Levels Of Metallized Films
by Thomas Dunn and Eric Jordan, Printpack, Inc.
Our company metallizes many grades of OPP and OPET films primarily for internal use in extrusion laminations with reverse printed OPP. Confirmation testing confirms the effectiveness of process control efforts for both processes. The laboratory regularly measures the oxygen and water vapor transmission rates of product sampled from both processes. Information in the paper summarizes the test methods and conditions used to generate the results discussed. This paper attempts to analyze these data to understand better the barrier levels now possible with commercial metallized films, the effects of a commercial barrier process on those levels, and actual barrier levels delivered to form-fill-seal packaging operations.
Advanced technology with surface modification and hybrid OPP base films provides robust, reliable barrier performance through converting operations. While oxygen barrier is lost, initial values are sufficiently low to give finished laminations low OTR. As a result, current barrier performance from barrier metallized OPET and OPP films provides a substantial structural component in barrier packaging materials.
First Principles Cause of Melt Fracture in LLDPE
by Dave Smith and Mike Andrews, Battenfeld Gloucester Engineering
Ignoring all the previous information available, our work looked for a simple physical explanation to explain some strange process problems encountered when blowing LLDPE film. The paper does not discuss the long and complicated process that led us to our conclusions but only presents a few of many observations made.
The paper presents a new and as yet unproven theory and the data gathered in support of that theory. We recognize that it is difficult to have every detail of a new theory correct when only a small fraction of the required research has been completed. We fully expect others will modify and improve the theory as new data emerges. The new theory explains melt fracture in LLDPE resins using volatile induced flow defects (VIFD). The theory and its resulting techniques have worked as predicted. Additional work is necessary to prove or disprove the theory and expand on the knowledge base relating to it.
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