Silicone rubber is a high performance elastomeric material. It has a wide variety of uses. Silicone is often used as seals or gaskets due to its flexibility and ability to be compressed between two surfaces. Other uses include flexible medical devices and tubing, prosthetics, surgical implants and special effects in the film industry. Thanks to its high temperature resistance, it is becoming popular in the kitchen for items such as non-stick bakeware and molds. Maybe the “non-stick” is a bit of a clue when it comes to trying to bond silicone material.
In its solid, cured state it is normally very flexible, stretchy and… hard to bond!
There isn’t much you can do to improve the surface of the silicone. It is always going to have plasticizers migrating to the surface to add to bonding woes! A solvent wipe with isopropanol will prepare the surface for bonding and remove any processing lubricants present and give a consistent bonding surface. Acetone can be a bit aggressive, and other cleaners, such as meths or white spirit can leave a residue. Always make sure all solvent evaporates fully before bonding!
This is quite a short section because there are not many industrial adhesive options available to a poor soul looking to bond silicone! Silicone-based adhesives tend to work well on silicone. However, if you are looking for a fast cure and to get away from isocyanate chemicals, options are limited. Prime the silicone’s surface with polyolefin primer such as Permabond POP, and then parts bond the parts with a cyanoacrylate. Permabond 2050 is a favorite for bonding silicone as it is flexible. It doesn’t affect the “feel” of the silicone – it can be very hard to detect the bonded joint as it remains soft like the parent material – this is great for seals and o-rings as you don’t end up with a “crunchy” hard bit.
To receive further information about the products recommended, please contact Permabond.
