__TROUBLE-SHOOTING GUIDES ON BLOWN PLASTIC FILM MANUFACTURING
One of the most common topics in blown plastic film is troubleshooting the manufacturing of the film. Today's film production lines move at such a high speed that any seemingly small problem can rapidly lead to significant lost production and scrap product costing convertors those precious commodities - time and money.
Here are three excellent troubleshooting guides for plastic film links for your use.
- HOW TO SOLVE BLOWN FILM PROBLEMS - this 33 page document is a great starting place for trouble-shooting. The table of contents at the front can lead you to more specific information quickly.
- Blown Film Processes and Troubleshooting - this powerpoint from TAPPI labels itself "The Ultimate Quality Control Tool". Over 60 slides in the deck and the figures are wonderful for finding the right terminology for your particular issue.
- Polyethylene Film Processing Guide - this eight page guide is quite helpful because it breaks out polyethylene film processing into both HDPE and LLDPE sections.
USE OF FROST-LINE HEIGHT FOR MACHINE-SIDE OPTIMIZATION OF PROPERTIES
Polyethylene film properties are fundamentally controlled by crystallinity and orientation. All of the processing variables such as blow up ratio, haul off speed and the rate of cooling as well as the equipment and resin specifics determine the crystallinity and orientation and thereby the film’s performance. Often various process variables are in conflict and there is a need to understand these interactions in order to optimize the properties of greatest value while trading-off other properties. A classic tell-tale for the extrusion operator is frost line height since as the melt temperature is decreased or the rate of cooling is increased, the frost line height will tend to decrease allowing less time for melt relaxation, molecular orientation and in turn reducing crystallinity and the properties which correlate to crystallinity.
The two papers provided below illustrate a number of useful examples utilizing these concepts.
VARIABLES THAT AFFECT/ CONTROL HIGH DENSITY POLYETHYLENE FILM OXYGEN/ MOISTURE BARRIER
Multiple layer polyolefin based films continue to be one of the preferred packages for both the food and medical industries. This paper discusses moisture and oxygen barrier for multi-layer films that include polyethylene as the primary film component. Such structures are useful for affordable films providing protection from insects, bacteria, germs and dust.
Correlation between Structural Parameters and Property of PE Blown Films
A variety of types of polyethylene (LLDPE, HDPE, and LDPE) were used along with variation in the process conditions of the film blowing process. Through design of experiment, correlations were developed between various processing parameters and mechanical properties including tensile, tear, dart impact, and clarity. Microstructural parameters were also studied including the degree of crystallinity, lamellar thickness, and crystal size.
Tie Resin Selection Tool
There are so many different flexible materials used for film and so many tie resins to choose from, it becomes difficult to figure out which tie layer to choose for a particular pairing of dissimilar film resins. The link below makes finding a starting place simple. Check it out.
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