Pressure-Sensitive Tapes are made with pressure-sensitive adhesive and some type of backing material such as film, fabric or paper. In this article, I’m going to focus on the film, foil, fabric or paper portion of the tape to provide a better understanding of why so many different types of materials are used. I’ll start by defining some common terms.
“Backing” is the film, fabric, foil, foam or paper portion of a one-side coated tape. Masking tape, for example, has a paper backing.
A “Carrier” is basically the same as a backing but indicates use in a double coated tape. Double coated tapes typically have a paper, film, foil, foam or fabric carrier.
The term “Substrate” refers to the material the tape is applied to. For example, if tape is adhered to a steel surface, the steel would be the substrate. A substrate can be just about any surface you can think of. The substrate can influence the type of carrier or backing used. Here are some examples:
Electrical tape is used on electrical wires. The wire is generally coated in PVC plastic, needs to stay flexible, and might be susceptible to heat, cold or other weather elements. At one time, someone figured out that flexible PVC – polyvinyl chloride- film has the perfect properties. The PVC backing is flexible and conformable to various contours. Once the tape is applied the substrate can still be bent or worked without affecting the adhesive bond. The backing also has good resistance to weather and environmental conditions. Another feature of the PVC film is its electrical insulation properties. These are some of the reasons why PVC backing is used for electrical tape.
Many of the finger bandages on the market today have a flexible, stretchable fabric as the backing. The stretch and flexibility of the fabric allows for greater conformability to body contours. The stretch allows the bandage to be applied tightly, yet flex and stay comfortable. The fabric is softer and stronger than the older vinyl type bandages and allows for comfort and longer wear. Since the backing is fabric, it has some breathability, which helps the wound heal faster as well.
In the automotive industry, various tapes are used in very specific applications. One high-performance application is protecting sensitive components from high heat, generally in the engine compartment. Pressure- sensitive tapes made with heat reflective backings are commonly used. Backings from simple aluminum foil to fiberglass/foil composites provide the heat protection needed. These materials reflect heat and thereby reduce the temperature that sensitive components are exposed to. Although heat shielding is the basic requirement of the backing, other features like conformability, thickness, and insulating properties are also important in certain applications. Additionally, these backings are also used in generators, tractors, heavy equipment, electronics, recreational vehicles and more.
As you can see – backings are selected based in the features and benefits needed for the application. The same holds true for the carrier of a double coated tape.
When the application is to join two uneven parts together, a double coated foam tape is often a good option. The foam will conform to contours and act as a seal. In this example, the tape will bond two surfaces together and act as a gasket to prevent dirty air from entering at the joint. Before the tape can be used it must be cut into a shape to fit the part. The foam carrier works because of its compressibility and conformability. Foam will provide the gap filling properties required to fill in the uneven surfaces. The carrier also provides some dimensional stability, which will help in die cutting the part.
Although this article has only skimmed the surface, I hope it helped you gain a better understanding of what goes into selecting a tape backing or carrier and why there’s such a wide variety of tapes.