Dow Corning has taken a step forward in silicone technology with a new silicone reactive hot melt product that combines the properties of instant adhesive and reliable sealant. HM-2510 is a low-viscosity, ultra-clear, 100% silicone product with no fillers. Applied at a temperature of 120oC, it provides an immediate bond with high green strength, allowing freshly bonded parts to be transferred immediately to the next operation with no hold time.
This combination of silicone sealant and pressure sensitive adhesive offers long term adhesion to a wide range of substrates, but Dow Corning is initially targeting the new product at plastic-plastic and plastic-metal bonding in the domestic appliance and automotive component sectors. HM-2510 is particularly suitable for bonding low surface energy plastics such as polypropylene and polyethylene, while its low elastic modulus allows a considerable degree of stress relief along the bond line, allowing for different rates of thermal expansion in dissimilar bonded materials. This generous ‘stretch’, coupled with high bond strength, makes HM-2510 a very suitable alternative to mechanical fasteners.
In terms of assembly operations, this new silicone hot melt offers many productivity enhancements. In addition to eliminating the need for clamps and holding areas, it can be sprayed over an area or automatically dispensed to form a dimensionally stable bead on non-primed surfaces, and remains workable for up to 15 minutes (24 hour pot life). When fully cured, the bond has a continuous service temperature range of –45oC to +150oC and is approved for applications involving contact with food.
Dow Corning has spent several years developing this product and claims that it is currently the only company to offer a silicone hot melt with this level of performance and optical clarity. Next year, the company expects to offer the first of a series of product improvements, including a reduction in the application temperature from 120oC to 70-80oC.