Ferromagnetic materials contg. phenolic resin binder - with fibrous filler, lubricant and iron powder

摘要

Ferro-magnetic compsns. contg. (a) 8-25 wt.% opt. modified phenol-formaldehyde resin, (b) 5-20% of fibrous filler, pre-impregnated with (a), (c) 0.5-1.5% lubricant, and (d) iron powder as remainder. Mechanical properties, magnetic permeability and performance are improved in comparison with known mixts. using furnace/epoxy resin or epoxy/novalak block copolymer as binder, which suffer from insufficient vibration resistance and elasticity. Pref. (a) is of novolak or resol type, opt. modified with 10-30% polyolefin and derivs., polyvinyl acetal or rosin. Pref. (b) is asbestos, glass or synthetic fibre, pre-impregnated with a 20-60% binder soln. Pref. (c) is a fatty acid, e.g. oleic or stearic acid, or salt, e.g. Ca stearate.