Often one requires a bond or an adhesive that is not permanent, and the adhesive joint needs to be debonded at a certain time. Uses for nonpermanent or "reversible" adhesives include nonstructural applications such as removable labels, surface protection films, easily placeable and removable notepaper, bonding credit cards to mailers, as well as semi-structural applications such as tooling placement, prototyping, disassembly of parts for reuse, and repositioning.
One of the most popular types of removable adhesive is the common pressure sensitive adhesive that is applied to labels. However, hot melt or heat reversible adhesives can also be considered removable as can certain UV cured adhesives.
Recently researchers have tried to imitate the adhesion forces of a small lizard called the Gecko. The Gecko can stick to walls and walk across ceilings with ease, yet run with ease when chased. The secret is weak molecular forces and surface geometry of the tips of the Gecko foot hairs. Thus, the Gecko's adhesive never leaves residue, never gets dirty and never wears out.
Humans seem to have developed a technology that comes close to our friendly Gecko's foot hair -- cling film. This is a relatively unique product that seems to imitate the Gecko's ability and requires no adhesion.
The term "cling film" is commonly used to refer to a film that can cling to a substrate without the use of adhesives. Cling films have been used to produce products that are intended to be removed or repositioned. Cling film is simply ultra-conformable, highly plasticized vinyl film that is calendered into a very smooth film. These materials are being commercialized as temporary labels, refrigerator stickers, decals, etc.
Vinyl cling film can be printed on and sticks by making intimate contact with the substrate. These materials adhere by closeness of contact and mechanical attraction. As a result, cling vinyl films are typically adhered to smooth, rigid surfaces such as glass windows, refrigerator doors, and so forth. They do not adhere well to porous, rough, or contaminated surfaces. These vinyl films are printed upon and used as removable labels, decals, protective films, etc. They are available in continuous film form from a great many suppliers.
A popular use for such materials in the US is the attachment of labels to auto windshields that indicates when your next oil change should be scheduled. At the time of an oil change, the auto mechanic simply writes on the film the mileage and / or date when the next oil change should be and places the sticker on the drivers inside window surface.
The simple vinyl cling film may be the beginning of an interesting phase in the history of adhesives. The commercial possibilities for removable adhesives appear to be very high. Removable labels, temporary attaching credit cards to mailers, postable notes, and bookmarks are only some of the possible applications. Future uses of these products may include applications such as easy disassembly of parts for reuse or recycling, removable electronic coatings, preparing modular assemblies for test and then disassembly for diagnostics, and advanced delatching and deployment mechanisms.