Implementing Proper Measurement

Pressure sensitive adhesives exhibit a distinctive characteristic of being permanently tacky at room temperature. They bond to surfaces under pressure through polar attractive forces instead of creating chemical bonds. The two primary categories are rubber and acrylic based adhesives. While rubber-based adhesives are more cost-effective, they do not offer the same level of physical and chemical stability as acrylic-based adhesives.

There are three unique methods for applying PSAs:

• Solvent-based – where the adhesive components are polymerized in solvent and then applied onto the web.
• Hot melt – where hot melt adhesive is applied onto the web and then cooled before or during winding.
• Emulsion-based – where the adhesive components are polymerized in water, applied onto the web, and then dried.

PSAs can be single-coated, double-coated, pattern-coated, and self-wound.

Single coatings are adhered to a single surface known as the face stock, which can be film, PE foam, paper, tissue, or non-woven material. A release liner, which is silicone coated and made of PET, PE, or poly coated Kraft, is then applied to protect the adhesive layer. Double coatings are utilized to bond two substrates together, with different PSAs applied on each side of a carrier such as plastic film, tissue, or non-woven material to enhance the adhesive configuration. Transfer tape is an unsupported adhesive film that is coated onto a release liner and is commonly used in medical packaging with pattern coating. Self-wound systems consist of face stock coated with PSA on one side and silicone release on the other, examples include diaper tapes and short roll lengths of tape. PSAs play a crucial role in the production of specialty tapes, medical packaging, surgical drapes, and laminated film.

There are two primary reasons why measuring coat weight is crucial. Firstly, for adhesive coating to effectively adhere to the desired area, it must be uniformly applied. This ensures a strong coefficient of adhesion between the two substrates. Secondly, in order to reduce the consumption of expensive acrylic, it is essential to apply the minimum amount of coat weight necessary to achieve adhesion.