Historically, the first adhesives were composed of vegetable and/or animal elements. The first adhesives based on rubber and resins with benzene then appeared. Since then, other adhesives such as acrylics and silicones have appeared. There is no such thing as a universal adhesive mass: each one has its own advantages and disadvantages, and the determination of the most suitable one is always the result of a compromise between the different characteristics.
How to choose your adhesive mass ?
The choice of adhesive mass is based on several criteria such as temperature resistance and duration of exposure to operating temperatures, resistance to aging, initial adhesion, type of substrate, conditions of use and of course cost. The length of time a tape will be used is a key criterion for selecting an adhesive. The importance of initial adhesion and final adhesion will vary depending on whether the application of the adhesive is permanent or temporary. It should be noted that tack and final adhesion are two different characteristics. A tape may have average tack, but very high final strength after 72 hours. The exposure temperature of the tape and the duration of exposure are also two essential criteria. For very high temperature applications (above 160°C) or very low temperature applications, only a silicone adhesive will be able to offer the desired resistance.
To make a silicone adhesive, a soft silicone gum is mixed with brittle silicone resin and cured to produce the adhesive. By modulating the amount of gum, resin and curing time, different types of silicone adhesive can be produced with optimized performance. Its initial adhesion is average but this adhesive mass has excellent resistance to high and low temperatures, UV, and solvents. On the other hand, its cost is the highest of the three adhesives. If you work in the industrial sector and want to use silicone professionally, you can turn to Elkem, an expert in this field.
The manufacture of a rubber adhesive requires the mixing of natural or synthetic rubbers with various components to create the adhesion. The chemical structure of the components is not changed. They are just combined together to produce the adhesive. Rubber adhesive has the great advantage of being very versatile in its use at a low cost. Its initial adhesion (also called tack) is excellent, but it generally has moderate resistance to aging, UV and temperature. Natural and synthetic rubber adhesives are recommended for bonding to non-polar and multi-purpose surfaces.
To manufacture an acrylic adhesive, components are formulated to obtain specific chemical structures for the desired adhesion. These undergo chemical modification during processing, which can be modulated according to the desired final adhesion performance. This adhesive has the particularity of being transparent and is therefore widely used for all applications requiring the assembly of transparent materials. Its initial adhesion is average but increases progressively over time. Its resistance to UV, aging, shear and solvents is excellent. Acrylic adhesives are recommended for permanent and outdoor applications. The vast majority of technical adhesives on the market have an acrylic adhesive mass
Each of these three adhesive masses can also have the property of being thermosetting: in this case, they require a polymerization cycle (time and temperature indicated in the technical data sheets of the products) thus making it possible to significantly increase the adhesive power and the resistance to solvents.