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Question
#1431
Subject: How do multiple corona treatments affect dyne levels?
We use a corona treater to raise the dyne level of film on our laminator, after it has been applied to raw board with an adhesive. When we hit the film with the treater, it typically raises the dyne measurement from about 32 to 36. If we were to hit the film again, would the dyne raise another 4 points or would it stay at 36?
Answers (links jump to full text of answer below)
#1432
Author: Eldridge M. Mount III, EMMOUNT Technologies
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Subject: How do multiple corona treatments affect dyne levels?
The second treatment step would not necessarily raise the dyne level another 4 dynes as in the first step. The actual increase depends on the film surface polymer type as well as the impact. A second pass may result in over-treatment, which could hurt bonding to ink or in other lamination steps by degrading the surface, so you must be careful about successive treatment steps. It is important to look at the treatment power applied to the film to determine the likelihood of polymer damage. The impact of repetitive treatment steps needs to be looked at in terms of what the treatment is supposed to do for the product
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#1457
Author: Larry Gogolin, Gogolin & Associates
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Subject: How do multiple corona treatments affect dyne levels?
What happens on the second pass can depend on many things. The level can improve, stay the same or even degrade. Part of this depends on how effective the first treatment was. If the voltage is too low or the components of the unit are not tuned up, you may gain. If the room humidity or temperature the web experiences after treatment are too high, you can lose treatment effectiveness. Contamination after treatment is also a possibility.
I am sure you cannot double the level with a second pass. Any increase gained will be slight. You did not mention what film you are using. For example, polyethylene and polypropylene both start at about 32 dynes and go to 36 with treatment, so your 4-point jump is very normal.
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