Injection-molded liquid silicone rubber (LSR) is used in the manufacture of many goods, from medical devices to cookware to electronics. The material offers many advantages:
- Softness and flexibility
- Thermal stability
- Low surface energy
- Biocompatibility (i.e., compatibility with human hosts in medical or infant care applications)
- Chemical resistance
- Ease of manufacturing
With so many pluses, LSR is being used in an ever-greater number of applications—many of which require that the silicone be bonded to other substrates. It is in the bonding process that LSR has shown one of its downsides: because of its ultra-low surface energy and chemical resistance, LSR can be difficult to bond to other materials.
While primers or special self-bonding LSRs can be used to achieve a bond between LSR and other materials, these solutions are far from perfect. Primers require extra process steps, specialized application equipment and management of volatile solvents. Self-bonding LSRs suffer from short shelf life and limited availability, not to mention their high price.
However, there is now a different bonding method to consider and that’s our new adhesion additive, Chemlok 3Stream (3S), to address the challenges associated with bonding LSRs. Chemlok 3S imparts self-bonding properties to non-self-bonding LSRs, eliminating the need for expensive self-bonding LSRs. Chemlok 3S has been proven to achieve LSR primerless adhesion to thermoplastics and clean metals, including polyamide (PA), polybutylene terephthalate (PBT), aluminum, steel, nickel and many more.
Chemlok 3S can be fed via a standard additive pump directly into the LSR feed stream, similar to colorant dosing. With no need for a primer, the time-consuming primer application process is eliminated from manufacturing efforts, as are the associated VOCs. Chemlok 3S can also be used with multi-shot applications or multi-material applications. The use of standard LSRs with this additive represents a great cost savings – up to 50 percent – over self-bonding LSRs, which are more expensive and have longer lead times.
Learn more about this groundbreaking new product and read Part II of our blog series, “Introducing Chemlok 3Stream: Tips on Using the New Additive in LSR Molding.”