Learn what makes tape stick!
Pressure-sensitive adhesive (PSA) tapes consist of a backing material coated on one or both sides with a permanent or temporary acrylic, rubber, or silicone adhesive, often supplied with a release liner. Depending on the component’s chemistry and the construction configuration, adhesive tapes are used for a wide range of applications.
The Pressure Sensitive Tape Council (PSTC) define PSA tape as a continuous flexible strip of cloth, paper, metal, film, or foam coated on one or both sides with a permanently tacky adhesive at room temperature that will adhere to a variety of surfaces with light finger pressure.
PSA tapes do not require activation by water, solvent, or heat. They work because of three unique properties: Adhesion, Cohesion, and Tack. These three properties balance each other out and can’t work without one another, meaning that it is impossible to have a tape with 100% of each. Adhesion is the bonding strength of the adhesive to the substrate. Cohesion is the inner strength of the adhesive. Tack is the immediate grip of the tape (adhesive) to the substrate (object).
There are three main groups of adhesives used in PSA tapes: rubber, acrylic, and silicone adhesive systems. Polymers can be a blend of natural or synthetic materials, with or without additives. The adhesive is coated on one or both sides of the backing material. When needing to bond to different energy surfaces, differential acrylic/rubber adhesives may be used. Each type of adhesive has different characteristics that affect production and end-user performance.
Rubber-based pressure-sensitive adhesive systems typically bond to a wide variety of substrates, including low surface energy materials, and satisfy most adhesion requirements. Due to their low-temperature range, poor UV and chemical resistance, they are best for indoor applications.
Rubber-based adhesives are divided into natural and synthetic rubber.
- Natural Rubber typically offers the highest adhesion and shear properties, compared to acrylic adhesives.
- Synthetic Rubber is broken down into three groups.
- Hot melt has low-temperature resistance and ages poorly.
- Solvent rubber has better temperature and aging performance, but still poor UV resistance.
- Butyl rubber offers excellent UV and aging resistance, but lower mechanical strength.
Acrylic-based adhesive systems are more versatile and a little higher cost than rubber-based systems. While rubber-based adhesives have a higher initial bond, the acrylic pressure sensitive adhesives go through a 24-hour cure cycle, allowing the bond to continue to improve over time.
Acrylic adhesives can either be Water-based, also referred to as Emulsion or Dispersion, or Solvent-based. Modified acrylics typically have superior adhesion to a wider variety of surfaces.
- Water-based are slower drying compared to solvent-based systems.
- Solvent-based systems are generally better resistant to solvents, chemicals, and water.
- Pure acrylic, also known as standard acrylic, have a lower tack and less adhesion to low-energy surfaces than modified acrylic or rubber adhesives.
Compared to acrylic and rubber adhesive, silicone is significantly more expensive. Silicone bonds to fewer substrates, but due to their excellent high temperature performance and chemical resistance, they are well suited for splicing tapes, polyimide tapes and medical applications, to name a few.
Medical Grade Adhesives
- Silicone Gels
A backing material, also referred to as facestock, carrier, or substrate, is a thin, flexible material that can be coated with an adhesive. A substrate can be made of cloth, non-woven material, film, metal foil, foam, rubber, paper, or laminate. These flexible materials offer a wide choice of performance and handling characteristics. When selecting a backing material, consider the thickness, strength, conformability, color and resistance to temperature, solvents, chemicals, moisture, and abrasion.