Morton International, Inc.

Morton Thiokol Inc.

Richard L Brook

A free flowing powder of discrete particles of a polar group-containing modified propylene polymer (MPP) is disclosed. This MPP powder has an average particle size of less than about 5 microns and comprises about 25-45 wt. % of discrete particles of the MPP and about 55-75 wt. % of a liquid which is a solvent for a film forming resin material, all wt. percentages being based on the total weight of the powder. The preferred MPP is maleic anhydride polypropylene. The preferred film forming resin solvent is methyl ethyl ketone (MEK). The MPP powder is adapted to be suspended in a primer composition containing a film forming resin, preferably an epoxy resin.

Free flowing modified polypropylene powder for prime compositions with

A process for preparing a free-flowing powder is disclosed, which powder is useful in primer compositions. The process comprises the steps of (a) dissolving a polar group-containing modified propylene polymer (MPP) at an elevated temperature in a solvent for the MPP, (b) cooling the solution to precipitate particles of the MPP, (c) collecting the precipitated particles by simultaneously centrifuging and spraying the particles with a liquid capable of removing the solvent from the particles and which is also a solvent for a film forming resin, such as an epoxy, which is present in the primer composition, (d) continuing step (c) until substantially all of the solvent for the MPP has been removed from the particles, and (e) collecting the resulting powder, which has an average particle size of less than about 5 microns.

Process for preparing a free-flowing, modified polypropylene powder

Primer compositions are disclosed which are a homogeneous, fluid, uncured suspension of discrete particles of a polar group-containing modified propylene polymer (MPP) in a film forming resin material, the particles having an average particle size of less than about 5 microns, and the primer composition being substantially free, i.e., containing less than about 5%, of a solvent for the MPP based upon the weight of said MPP. The preferred MPP is maleic anhydride polypropylene. The preferred film forming resin material is an epoxy resin. The particles of MPP are present in the primer in an amount of at least about 3%, preferably at least 40%, by weight based on the weight of the nonvolatile content of the primer. A free flowing powder adapted to be suspended in the primer composition is also disclosed which not only has an average particle size as above stated but comprises about 25% to about 45% by weight of discrete particles of a MPP and about 55% to about 75% by weight of a liquid which is a solvent for the film forming resin material of the primer, all percentages by weight being based on the total weight of the powder.

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Harvard, IL, United States of America

Richard L Brook