Questions and Answers specializing in the adhesives, sealants and coatings industries.
We have recently encountered a problem in converting label stock we purchase for specialty EDP labels that we print, slit, die-cut into sheets and box for our customers. One of our label-stock suppliers convinced us to change the adhesive on this label stock from an acrylic to a hot melt, which is saving us money. However, we are finding it more difficult to slit and die-cut this material, and it is causing a lot of downtime. There seems to be a lot of adhesive buildup on our cutting and slitting tools. What might be causing this problem?
This could be a very simple or a very complex problem, and there are a few obvious things to consider. Many acrylic pressure sensitive adhesives (PSAs) are at least partially crosslinked and have good thermal resistance. Most hot melt pressure sensitive adhesives are reversibly thermoplastic and will soften under heat. Certainly, your converting processes generate heat. This might be causing the hot melt PSA to soften and gum up your tooling. You might try chilling your cutting tools to see if this will alleviate the problem. If not, you might be able to get a similarly low-cost label stock from your supplier with a hot melt adhesive that has a higher temperature resistance, or shear adhesion failure temperature (SAFT).