Pressure-sensitive tapes are made with pressure-sensitive adhesive and some type of backing material such as film, foil, fabric or paper. This article will provide a better understanding of why so many different types of backing materials can be used successfully when crafting tape. But first, let’s jump into defining a few common terms from the industry.
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 is used in double-coated tapes, which 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 were adhered to a steel surface, the steel would be the substrate. Substrates can be almost any surface the imagination can dream up, as tape can stick to most things. The substrate influences the type of carrier or backing used.
Here are some examples:
- Electrical tape is used on electrical wires, and those wires are generally coated with PVC – polyvinyl chloride – plastic. That’s because the wires need to stay flexible and might be susceptible to heat, cold or other harsh elements. In the past, someone figured out that flexible PVC film had the perfect properties to withstand these conditions and could serve as a tape backing. PVC backing is also flexible and conformable to various contours. Once the tape is applied to the wires, the substrate can still be bent or worked without affecting the adhesive bond. The backing of electrical tape likewise has good resistance to weather and environmental conditions. Another great feature of PVC film is its electrical insulation properties. These are some of the key 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 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 for this. Backings from simple aluminum foil to fiberglass/foil composites provide the heat protection needed to get the job done. 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, and recreational vehicles, among other things.
Therefore, backings are selected based on the features and benefits needed for the application. The same holds true for the carrier of a double-coated tape.
When the application calls for joining 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 way, 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.
This overview barely skims the surface of the many considerations tape manufacturers must address. Yet it hopefully provides a window of understanding into what goes into selecting tape backings and carriers and why there is such a wide variety of tapes.