Westvaco Corporation

Giancarlo A Cavagna

Joseph M Murphy

Robinson Camden Claytor

Domenick Larry Raschella

Ernest J Groome

Barrier coatings are disclosed to reduce the migration of contaminants from paperboard into food products packaged in containers prepared from the paperboard. The barrier coatings operate to either absorb the contaminants or provide a tortuous path to their migration from the paperboard particularly at the high temperatures reached during the cooking of the food products in microwave ovens.

Barrier coating to reduce migration of contaminants from paperboard

Unbleached paper and paperboard for use as outer packaging material is coated and printed on a printing press. The unbleached rawstock must be relatively smooth and nonporous prior to coating and printing with a Sheffield roughness less than about 300 units for linerboard and less than about 330 units for folding carton material. The coating formulation preferably comprises a mixture of temperature insensitive binders and pigments having a viscosity lower than normal paper coatings, and is applied in layers of about 1.5 lb./1000 square feet up to a total of about 5 lb./1000 square feet. Best results are obtained when the coated surface is doctored with a blade or fixed roll after coating and before drying to achieve a smooth surface for printing on the same or a different press.

Method for making coated and printed packaging material on a printing

A process and apparatus is disclosed for dry refining cellulosic pulp wherein the liberated fibers are structurally deformed and twisted without producing unwanted knots or fiber bundles. For the purposes of the invention, a disk refiner is used which is modified to include one or more air jets located at the periphery of the refiner housing. During refining, the refiner is provided with a cooling means, while air is introduced into the housing through the air jets to prevent fibers from becoming trapped between the ends of the refiner disks and the housing walls, thus preventing the formation of knots and fiber bundles.

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Silver Spring, MD, United States of America

Giancarlo A Cavagna