Induction Bonding of Plastics and Organics with a Nonmetal Bonding Agent

Useful heat for bonding of plastics and organics can be generated by induction hysteresis heating of iron oxide particles at megahertz frequencies. The heat is generated even though the particles are only micron size and electrically insulated from one another in a plastic carrier. The principles and applications of this process differ from other induction methods in that the heat-generating material can be applied as either a solid or a liquid, a flexible bond is achieved, and nonplastic nonmetals can be bonded. Numerous advantages are achieved because the heat is generated directly at and only at the joint interface with no need for heat transfer. Many applications are feasible for heat sealing, bonding, accelerated drying, and other heat-dependent processes applied to wood, paper, plastics, leather, corrugated board, rubber, fabrics, or essentially any electrical nonconductor that can be heat sealed or adhesively bonded. Special coil designs have been developed to help provide the desired intense fields at the typical operating frequency such as 4 MHz.