Ask Dr. Dave
Question: Do you know of an adhesive that retains its tackiness, similar to the material used in adhesive traps for rodents?
Answer: The adhesive you refer to is a pressure-sensitive adhesive (PSA). PSAs are formulated in different ways using a range of raw materials to produce varying degrees of tack, shear strength, heat resistance, etc. What you need to do to approximate the tackiness of rodent traps is source some polyisobutylene polymers. This polymer is chemically similar to butyl rubber but is not crosslinked. These polymers come in various molecular weights and can be blended to get the right amount of tack. Low-molecular-weight polymers have the highest tack, and you can apply the polymers either from a solvent or from the melt.
Question: My company uses a process in which wool-based mineral board is preheated prior to being laminated to fiberglass scrim. We currently use a polyvinylacetate adhesive. It is applied to the scrim via forward roll coater and then laminated to the mineral board through a pair of heated calendar rolls. To date, we have been unsuccessful in creating a laminate that is relatively flat and exhibits good adhesion. We have done all we can with the current laminator, process conditions and selected materials to meet both requirements, but without success. What types of adhesives would you suggest we try?
Answer: It sounds like you might be getting excessive shrinkage coupled with poor adhesion. You might consider using a very high solids emulsion adhesive, or a highly filled one that will allow for less shrinkage. You might also try a polychloroprene adhesive; emulsion versions of these are now available as alternatives to solvent-based ones. One other alternative might be to use a reactive hot-melt adhesive, but this will require some investment in application equipment.