US Patent 7951419 Dry-coated oxygen-scavenging particles and methods of making them

Heterogeneous oxygen-scavenging particles are formed by dry coating activating component particles onto oxidizable component particles, largely through a succession of mechanical motions. The component particles are repeatedly mixed, compressed, and sheared. Smaller activating component particles coat the surface of larger oxidizing component particles by force-induced contact, while irregularities are removed by abrasion among the particles. The oxygen-scavenging particles can be blended together with a base polymer into a masterbatch having a higher concentration than required for use as an active barrier to oxygen permeation. The masterbatch can be diluted with the same or a compatible polymer to form the active barrier.