New developments in micapaper with improved properties for the electrical tape insulation industry

Summary form only given. New mica papers in muscovite and phlogopite minerals as well as calcined muscovite papers have been developed for the electrical insulating tape industry. These papers offer improved resin penetration time, greater porosity, and added flexibility. The adhesion between the mica particles has also been improved. In practical terms, the improvements will have a direct effect on the rate of resin absorption and tape drying. The good interlaminar flake adhesion prevents the generation of dust at the factory level while the added flexibility helps promote a smooth and regular surface during the winding of the coil. Faster penetration and porosity values will also allow a thicker tape to be vacuum pressure impregnated. The ratio of mica to the thickness of insulation is increased, therefore optimizing the insulating value of the system. These papers are all mechanically produced, and are thus free of any chemical impurities that might affect the polymerization rate of resins added to the paper to manufacture a tape.<>