Permanent magnet composites and method therefor

DETAILED DESCRIPTION OF THE INVENTION The present invention pertains generally to magnetic composites comprised of a polymer matrix having dispersed therein a quantity of hard magnetic ferrite particulates.
The polymer matrix is based upon various liquid rubbers, and may be selected from a large variety of effective chemical compounds.
The hard magnetic ferrite particles are represented generally by the formula MO.
n Fe.
sub.
2 O.
sub.
3 ; wherein M is selected from the group consisting of barium, strontium, lead, and mixtures thereof; and, n has a value of between about 4.
5 and about 6.
2.
Various additives to improve the compatibility of the ferrite particles with the polymer matrix, thus improving the relative amount of particulate which may be dispersed in the matrix, or additives to tailor the viscosity of the polymer may, preferably, be present.
In order to more fully elucidate upon the various objects and advantages of the present invention, the following detailed description will be given in terms of various preferred embodiments and exemplified with respect thereto.
However, this is intended to be illustrative and in no wise limitative.
The polymeric matrix of the present invention is based on a liquid rubber and may be selected from the liquid polybutadiene, liquid polyisoprene, liquid polyisobutylene, and the corresponding liquid copolymers thereof, as well as such polymers modified by hydroxyl, carboxyl, maleic anhydride, isocyanate, acryl, and other similar groups.
Blended matrices comprised of the aforementioned liquid polymers and liquid polymers containing a small amount of a solid rubber are also envisioned within the scope of the present invention.
It has been determined that the viscosity of the liquid polymer matrix must be within the range of from about 10.
sup.
3 to about 10.
sup.
6 cps (Brookfield viscosity at 25.
degree.
C), and preferably within the range of from about 5 .
times.
10.
sup.
3 to about 5 .
times.
10.
sup.
5 cps.
As will be more fully described hereinbelow, various additives may be incorporated to properly tailor the viscosity of the polymer matrix