Pressure Sensitive Adhesive
3M, the manufacturer of Scotch Tape is highly secretive about its process. 3M was one of the first companies to begin making this type of tape and regards its process as a complete and total secret. Richard Dew, the inventor of Scotch Tape, actually worked for the company during the 1920s in the Research and Development department. He created masking tape and adapted that formula to create Scotch Tape. He found a way to attach adhesive to cellophane tape, which was completely clear. Dew used a series of polymers and adhesives that dried slightly when added to the surface of the tape. The formula itself is a trade secret, but it involves using a special type of pressure sensitive adhesive developed by the 3M company.
Polymers
Scotch Tape relies on a special series of polymers to work. Polymers are types of molecules that attach together to form long chains. The original polymer contained rubber, natural oils and synthetic resins. Today 3M and other companies making similar types of clear tape use a polymer that includes acrylics in the blend. Acrylics are noted for their strength and durability, as well as their quick drying capabilities. The polymers are mixed together to form a material and heated until it takes on a liquid consistency. The liquids slowly applied to sheets of clear plastic or cellophane. The pieces are then cooled, which causes the adhesive to dry slightly, while still maintaining its sticky feel. They use evaporation or add chemicals to remove the liquids and then dry out the pieces.
Sticking
One of the most common theories regarding how Scotch Tape works and why it remains sticky involves the use of bubbles. While the surface of the tape appears smooth and flat, it actually contains a series of small bubbles. When adhesive is applied to the surface of the tape, it's impossible to remove all the air bubbles and make the surface completely flat. There are small areas where the bubbles rise off the surface and dip back down. This creates a series of small valleys in between the bubbles. When the tape is laid onto another surface, it traps air inside those valleys. The air bubbles function as a sticky substance and attach themselves to the surface of the object and add even more adhesive. The bubbles actually cause the rises on the tape to attach to the object. When viewed under a microscope, this is all evident.
