Thermoplastic Magnet Having Highly Improved Heat-Resistance

Plastic magnets were formed with SmCo5 powder using nylon-12 (PA-12), and PBT (conventional type and low-viscosity type) binders. The magnetic properties and resistance to thermal degradation were studied. Whereas general magnetic properties were best for PA-12 magnets, such properties as the flexure strength and heat resistance were better for PBT magnets, directly reflecting the binder properties. When metal, oxide, a heat-resistant coupling agent, and a conventional coupling agent were used to coat SmCo5 powder, the best stability against heating was obtained for the metal coating (stable to above 300°C), followed by the oxide coating, heat-resistant coupling agent, and conventional coupling agent.