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Question
#925
Subject: The cell pattern on the cylyinder is seen on the coated part after the coating is transferred on to the substrate. How do we eliminate?
Among several gravure cylinders that we use, we also use a trihelical type gravure cylinder. Coating with this cylinder has been challanging. We get what we call as the TH marks and also the cell pattern on the cylyinder is seen on the coated part after the coating is transferred on to the substrate. This makes the coating look very ugly. We feel that it may be a flow issue of the coating. Is there anybody who have had this issue when using the TH cyinders for gravure coating?
Answers (links jump to full text of answer below)
#926
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Subject: The gravure pattern you are seeing is always there at some level in the
gravure transfer.
The gravure pattern you are seeing is always there at some level in the
gravure transfer. You are right that it may be lack of leveling. You can help
this by lowering viscosity and surface tension. Solvent fluids are less prone
to this defect. It is most prevalent in direct gravure and less in offset.
Another solution often used is placement of a "zero" bar or smooth rod inches
after the film leaves the gravure nip. This will help level the fluid by
pushing the peaks into the valleys.
If you are applying a thick coating, you may east the problem by using a fine
screen (200 lpi) and make two passes to help cover the pattern. You might
also use a thin "skim" coat for the same purpose.
Larry Gogolin
Gogolin & Associates
978-779-9845
Lgogolin@aol.com http://members.aol.com/lgogolin/coating/index.htm
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