Since the invention of the first adhesive using birch bark tar, the fundamental principle of adhesion remains the same: use of a flowable raw material to hold two substrates together. Today, advances in naturally derived and synthetic materials have resulted in two common formats for the creation of industrial adhesive products. The most common types of industrial adhesives are liquid adhesives and tapes.
By a physical change or chemical reaction, a liquid adhesive applied between two substrates forms a solid material that bonds the substrates together. Liquid adhesives are available in several formats, providing manufacturers with opportunities to offer customers a liquid adhesive to meet various specifications.
Solvent- and water-based adhesives use a liquid carrier (solvent or water) to apply the adhesive to the substrates. The carrier evaporates and the adhesive remains. Common delivery methods include tubes, pails and aerosol cans.
Tapes are pressure sensitive adhesives, so called “PSAs”, and due to their performance characteristics they can provide freedom when designing a product and increase production efficiency. They are provided fully cured so there is no additional curing that takes place to form a bond. PSAs bond on contact with pressure applied. Bonds are performed by using mechanical interlocking and electrostatic interactions at the interface. The customer is provided with a fully cured material with the viscoelastic properties necessary to hold two materials together, often through the use of pressure.
Pressure sensitive adhesive is laminated with a pressure sensitive adhesive on either side of a foam carrier (e.g. acrylic, urethane, polyethylene). This allows the tape to have different functionality on the A and B sides, plus the foam provides unique gap-filling or elastomeric properties.
An endless variety of design requirements has led to the development of a wide variety of adhesive and tape products and formats. This broad range is represented in the spectrum of bonding technologies known at 3M as the adhesive and tapes bonding continuum. This continuum of adhesives and tapes ranges from removable pressure sensitive adhesives similar to that seen on Post-It® Notes, to high-strength curing epoxies used to bond components of airplanes.