What is Pressure Sensitive Adhesive Tape?
Pressure Sensitive Adhesive (PSA) tape consists of a backing material coated with an adhesive on one or both sides of the backing. PSA tapes do not need water, solvent, or heat to adhere to a surface. They work with light finger pressure. Masking tape is a popular type of PSA tape that most people are familiar with. PSA tapes have many different configurations and chemistry that make them valuable for a wide range of applications.
What Is the Structure of Adhesive Tape?
The anatomy of PSA tapes is composed of different elements that influence their ability to adhere to pre-determined types of surfaces, their adhesion strength, their durability, their resistance to environmental conditions, etc. Depending on the combination of elements chosen, the PSA tape will be more appropriate for a specific application than for another.
Let’s take a look at the elements that will impact the selection of the right PSA tape: backing material, adhesive, release liner, primer and topcoat.
Backing Material or Carrier
PSA tape backings, also called the carrier, are what the adhesive is applied to. The backing is one of the most important parts of the structure of the tape. The carrier doesn’t only transport the adhesive, it also protects the adhesive and helps maintain the shape and stability of the tape. The backing material can be plastic, paper, fabric, foam, and more.
The backing material can be designed to withstand different forces or meet certain performance standards such as greater temperature resistance, strength or effectiveness as a moisture barrier. Some carriers are very thin, while others are thick, which may allow them to act as a sound absorber or fill a void.
In the printing industry, the backing material, called facestock, is used as a printing medium for custom printed tapes that can showcase brands, provide handling instructions and more. Once printed, this material is covered with a top coat to protect it from various elements and discoloration.
The adhesive is probably the most vital part of any PSA tape. The main types of adhesives are:
● Rubber: Rubber comes in both synthetic and natural bases. Rubber-based PSA tapes are best for indoor applications because they have a low-temperature range and poor UV resistance. Rubber does have good adhesion properties.
● Acrylic: Acrylic adhesives are either water- or solvent-based. Acrylic PSA tapes have more versatility than rubber-based PSAs, but acrylic tapes may need time to cure to get the strongest bond.
● Silicone: Compared to acrylic or rubber PSAs, silicone is more expensive, but it does have distinct advantages over the other adhesives. Silicone is often used in medical equipment. It has a high-temperature performance and bonds to flesh without harming the skin.
Adhesives are classified according to certain factors, including adhesion, cohesion, and tack. Adhesion is how strong the adhesive bonds to the substrate, which is the surface of the item that the adhesive is in contact with. Cohesion is the strength of the adhesive. Tack is how well the adhesive grips to the object.
Release LinersThe release liner is a paper or other type of film that protects the adhesive as it unwinds from the roll. If you’ve ever used carpet tape or a band-aid, you have used a release liner. The release liner keeps the tape from adhering to its own backing until it’s ready to be applied to the desired surface. Release liners are usually disposed of by the user once the PSA tape has adhered to the substrate. Release liners can be designed for the application, whether manual or mechanical applications.
PrimerA primer can help increase the stickiness of the adhesive to the backing or to the substrate. If the substrate is rough or difficult to bond with, a primer can boost the bonding properties. A tape primer can provide a cleaner surface for bonding and improve the capability of the carrier to stay attached to the adhesive while bonding. Since it is not always a part of the tape, your provider may recommend it, depending on your application needs.
TopcoatThe top coat, also known as the laminate, protects the ink printed on the facestock and increases its adhesion. This layer can be offered in different colors and gloss levels.
Different Pressure Sensitive Tapes, Different Construction Types
Using the above components, PSA tapes can be configured to meet many applications across any industry.
Single-Sided TapeSingle-sided tape has adhesive applied to one side of the carrier. It may use a release liner to protect the adhesive. Using different types of carriers and adhesives can give you a few options to find the right solution for your application.
Double-Sided TapeDouble-sided PSA tape has a carrier coated with adhesive on both sides. Double-sided tapes have a liner to protect the top adhesive. With double-sided tape, the adhesives can be designed in any combination to match different substrates. Medical tape, for example, may have one type of adhesive that sticks to the medical device, while the other side would be silicone-based to stick to the skin.
Adhesive Transfer Tape
Adhesive transfer tape is a thin coating of a PSA on a release liner without a carrier or backing. The benefit of this is that the tape is conformable to the substrate, increasing the bonding capability. Transfer tape can be difficult to work with in certain applications, but many industries use transfer tape to replace rivets and other connectors. It’s important not to confuse transfer tape with double-sided tape.
Self-wound tape is a type of single-sided PSA tape without a release liner. Many commercial tapes are self-wound—cellophane, masking, and electrical tapes are all self-wound tapes. Packaging tapes are usually self-wound tapes. These tapes are inexpensive but may not have the wide range of options that other tapes have.
Choosing the Right Tape
As you can see, the multiple combinations of backing materials and adhesives, with release liners, primers, and top coats offer many possibilities for pressure sensitive adhesive tape design. Therefore, it is the requirements and constraints of a specific application that will determine the right combination to use when creating a custom PSA tape.
The professionals in the tape industry are well-versed in the solutions that exist to meet the needs of various applications. They are also adhesive experts and can help you develop a custom PSA tape for your application.
MPI Matco specializes in the distribution of manufacturing and industrial pressure sensitive tapes, as well as the design and manufacturing of customized PSA tapes. We are able to find the best combination of adhesive, carrier, release liners and more for all types of applications, regardless of the industry.