Minnesota Mining and Manufacturing Company

Norman E Gehrke

John D Munter

Robert P McCollam

Karl J Warren

Donald M Lewis

Kevin K Kuck

Joseph H Lam

Michael J Brost

Mark D Larson

George D Kostuch

Thomas W Braid

A coater incorporates a die, a reservoir, a gravure cylinder, and a doctor blade for applying coating fluid to a moving surface. The flow rate of coating fluid to the gravure cylinder is controlled to equal the rate at which coating fluid is consumed by the coating process. This eliminates the need to recycle surplus coating fluid. The coating fluid can be quickly and conveniently replaced with a solvent in the reservoir when coating is not being performed to reduce the occurrence of coating defects arising from excessive evaporation of solvent and premature solidification of coating fluid.

Non-recirculating, die supplied doctored roll coater with solvent

A magnetizable layer can be applied to a flexible backing web by gravure coating at high speeds by independently driving the backing web at a speed that is substantially different from the surface speed of the gravure roll. Especially high coating speeds have been achieved when the gravure roll rotates oppositely to the direction in which the backing web is advancing. In one embodiment, a nip roll presses the backing web against the backup roll, there is a gap between the gravure roll and a backup roll, and an idler roll is positioned downstream of the gap to force the backing web into contact with the gravure roll over a short arc. When that backup roll has a hard surface such as metal, its surface can be machined with precision, and that precision can be maintained in spite of exposure to solvent vapors.

Differential-speed gravure coating of magnetizable layers in the

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Browton, MN, United States of America

Norman E Gehrke