Silicone Rubber, a "Low Surface Energy" Elastomer - What Does This Mean?
Silicone is a high-performance elastomer with the ability to withstand extreme temperatures, both high and low. It also naturally repels, which makes it an excellent choice for a water seal or a moisture barrier. However, this also makes silicone tricky to bond to other surfaces.
When bonding dissimilar materials, the surface energy of each is an important consideration. Materials with a high surface energy have a molecular construction that provides a more accepting bond than materials with low surface energy, which resist bonding. Silicone is a low surface energy elastomer.
Surface Treatment
A silicone adhesive will bond quite well to silicone rubber. However, an acrylic or rubber-based adhesive will not bond securely to the silicone without some help. Help most often comes in the form of a surface treatment of the silicone, such as priming or corona treatment. Both effectively alter the surface energy of the silicone: one chemically, the other with an electrical plasma charge. Both methods of surface treatment are capabilities that Marian can provide.
Differential Double Coated Tape
Another alternative to providing silicone rubber with an acrylic pressure sensitive adhesive is the application of a differential double coated tape. Pressure sensitive adhesive (PSA) products like 3M 9731, tesa® 61529, and PSI-1186 are constructed with a polyester film coated on one side with a silicone adhesive, and on the other side with acrylic adhesive. Assuming the silicone surface is free of lubricant (like talc), the silicone PSA readily bonds there, leaving the acrylic PSA protected by a release liner and ready to bond to the other surface. Marian sources all of the differential PSA products mentioned in this article and can provide samples and/or prototypes.
Differential Double Coated Tape Data Sheets
Is Silicone Rubber Right for Your Design?
The ability to bond to a silicone surface is one of many key factors you should examine when considering silicone rubber material for your design. We encourage you to download our Free eBook, Pros and Cons of Designing with Silicone Rubber to learn more about this high performing material.
Let Marian Help with Silicone Rubber Material Selection
Material selection can be an overwhelming process. Marian engineers are available to help you weigh out your many options, providing data, material samples, and rapid prototypes. Contact us today!
