Pressure-sensitive adhesives (PSAs) have become a part of everyday life. We find them on many of the products we purchase as primary labels, price stickers and UPC labels. We use them in the form of plastic bandages, duct tape and clear package sealing tape. We know what we use them for, but how are they made?
PSAs are a combination of several materials that come together to form a "construction." A PSA construction is a combination of layers including a facestock (label) or backing (tape), an optional primer coat, an adhesive, and a silicone release coating on a protective liner. The PSA construction - whether a label, tape or transfer adhesive - is manufactured through several coating and laminating steps, including liner-release coating, adhesive coating/drying/curing, optional facestock or backing primer coating, and lamination of the facestock or backing to the liner.
One of the least-discussed aspects of PSAs is that of adhesive coating and adhesive coating methods. The objective of adhesive coating is simply to uniformly deposit a pressure-sensitive adhesive onto a web substrate.