Understanding Pressure-Sensitive Adhesives and Performance in the Field

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colorful Pressure Sensitive Adhesives Pressure-sensitive adhesive tapes (often referred to as adhesive tape, sticky tape, or just tape) utilize a family of permanently tacky adhesives designed to be applied with light pressure. These adhesive systems differ from other types of adhesives in that they don’t require any type of moisture, oxygen (or lack of oxygen), solvent, or heat to establish a bond. There are literally thousands of different tapes available on the market. Some of the differences among them are significant and in other cases the differences can be extremely subtle. For purposes of this article, we will focus on tapes used for bonding and assembly applications primarily in manufacturing settings. The first set of “screens” to help narrow the myriad of tape options include:
  1. The type of assembly being considered
  2. The materials to be bonded (substrates)
  3. The manufacturing process itself
  4. What the product encounter during its’ life cycle(end use requirements)
  5. Cost considerations

Type of Assembly

Getting clear on the type of assembly you are designing seems rather obvious but it really does help separate the ‘wheat from the chaff”. Is it a small area bond such as a wire management hook, screw anchor, or metal or plastic housing? Is it a gasket or seal? Is it filling a gap? Are you attaching trim, nameplates, or badges? Are you fabricating more structural components such as bonding large metal, glass, or composite panels to a frame system?

Materials to be Bonded

Simply put, not all tapes stick to every surface. For example, some adhesive systems have tenacious bonds to bare metals but will not adhere well to a painted metal surface. Pressure –sensitive adhesives work primarily through a concept commonly called  “wet out “ or the ability to flow and develop intimate surface contact with the substrates. Wet out is a function of surface energy, surface texture, and cleanliness. Some materials such as stainless steel, polycarbonate, and polystyrene have higher surface energies and are easier to bond to while other substrates such a polyethylene, polypropylene, or PVDF (polyvinylidene fluoride) can be much more challenging. Various tapes have been designed with adhesive systems to work effectively with all of these surface energies. The texture of the surface can also play a role in bond strength. Softer adhesive can systems “flow” into the microscopic “hills and valleys” in  the surface to develop increased surface area and bond strength while firmer systems might adhere primarily to the “peaks” and generate lower adhesion values. Cleanliness can significantly influence tape performance and service life. Manufacturers all indicate that the surface should be clean and free of dust, dirt, moisture, and other fluids such as oils. The presence of these contaminants block the adhesive from establishing intimate contact with the surface thus reducing or compromising bond strength.

The Manufacturing Process

How do you manufacture the assembly now? Is the process locked down or is there any room for change? How many steps are there in the current process? Will you apply the tape by hand, via a laminating system, or via an automatic or semi-automatic applicator? The beauty of tapes is their versatility. Small parts might be able to be applied via hand quite easily while other tape require more robust and consistent pressure to ensure long service life and performance.

End Use Requirements

Will the final product be used indoors or outdoors? Will it encounter any chemicals? If so, what chemicals must it resist? Will the tape be asked to resist very high or very low temperatures? Tape manufacturers have done an outstanding job formulating adhesive systems to withstand almost anything you can throw at them. Doing the homework up front saves surprises later when you find out that a bond is compromised and worse, yet, you have an upset customer.

Cost ConsiderationsPressure Sensitive Adhesives on rolls

Tapes vary widely in cost depending on what they are made from what they are being asked to do. There are very inexpensive tape products that will do some jobs very nicely but they operate in a very narrow performance range and can give  some nasty surprises if specified in an application beyond their means. In many assemblies, the unit cost of the tape is very low. Mere pennies in some cases and much more in others. The more interesting question is what will a tape allow you to do? It’s the total applied cost exercise. It’s a harder concept to think about but it makes a huge difference! Tapes let you select lighter weight materials in many cases. You eliminate rework, clean up, replacing mechanical fasteners, and a host of other benefits that are often overlooked when considering costs. Tom Brown, Inc. has a wide selection of bonding and assembly tapes to meet the needs of manufacturers. Contact Tom Brown today to learn more.
Rick Alexander

About the Author

Rick Alexander is the National Sales Manager for Tom Brown, Inc. His early experience was in R&D, product management, and sales management for both Main Tape and Adhesives Research, Inc. Rick brings over 40 years of pressure-sensitive tape experience and Tom Brown’s world class converting capabilities to help solve customer bonding, assembly, and sealing challenges.