In-Mold Bonding of Fluorosilicone Onto Thermoplastic Substrates

Fluorosilicone (FVMQ) is used in sealing many automotive and aerospace applications. With light weighting of components so critical to fuel savings, many designs seek to integrate the FVMQ seal to the rigid thermoplastic. These designs make the component easier to assemble, sure fitting, and lighter weight.

Lord Corporation offers new technologies in IMB (in mold bonding) primers for overmolding of fluorosilicone rubber to a thermoplastic component. Mixing parts A&B of the primer and applying it to the thermoplastic component prepares the surface for bond formation. Overmolding a specially formulated fluorosilicone with added adhesion promoters provides optimal adhesive strength and is resistant to harsh environments.

A study of variables which include thermoplastic substrate type, application method, fluorosilicone grade, and conditions of curing the composite are compared. Comparisons are made in bond strength per ASTM D429 Method B (and other test methods) after exposure to heat, fuel swell, and water immersion. Surface structures of the bond formation are examined and considered as further detailed understanding of the chemical structure of the substrate-to-primer and primer-to-rubber interfaces.