Ask Dr. Dave
Is there a PSA that can be removed and reapplied a number of times without losing adhesion?
Dave Dunn's May 2017 column.
Question: We have a customer who wants to use an adhesive-backed expanded PTFE gasket strip on a steel substrate. However, the customer wants to be able to remove and reapply the strip without losing adhesion. We do not make ePTFE gasket strips, but we have imported some samples for the customer to test. They are not satisfied with the results. I must admit, I am not surprised. Is there such a thing as a PSA that can be removed and reapplied a number of times without losing adhesion?
Answer: As you probably know, bonding to a low-energy “non-stick” surface like PTFE is not easy. However, pressure-sensitive PTFE materials frequently use a silicone pressure-sensitive adhesive (PSA) because of good adhesion and the ability to use the material at high temperatures. I recently tested such a combination on an aluminum surface by applying it, leaving for 24 hrs to develop adhesion and then peeling it off the substrate. After re-applying and subsequent testing, the peel adhesion was still quite high. A few suppliers can help you with this application.
Question: We are looking for an adhesive for holding some metal parts together; however, we want to be able to break the bond before some final finishing operations. What do you suggest?
Answer: Several low-strength adhesive systems might be suitable. Many hot melts, for example, will give decent bond strengths but can then be broken apart with a sharp impact or by heating. Another simpler alternative might be to use a PSA or double-sided tape. They are available with different levels of tack and strength. ASI
Any views or opinions expressed in this column are those of the author and do not represent those of ASI, its staff, Editorial Advisory Board or BNP Media.
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