| 摘要 |
Closures for plastic containers are contour-sealed by heating inlays placed inside, using a material made of, or a thermoplastic one containing, inductively conducting and/or ferromagnetic substances which is heated by subjecting it to a rapidly alternating magnetic field. Against the inside of a urea-formaldehyde screw cap or like a sealing material is placed pref. composed of PVC- diisooctyl phthalate plastisol filled with 20-60% wt. fine Al, Cu, Fe/Ni powder to be excited, thus, heat softened by eddy currents or hysteresis losses due to e.g. 27.12 megacycles provided by a 5KW induction generator. Readily forming contour sealing inlays into plastic caps e.g. for containers for food or chemicals, by heat softening the inlays through eddy currents and/or hysteresis-loss excitement. |
