| 摘要 |
A coating head for use in strip-coating paper-card material with water-based, thixotropic magnetic recording ink, in order to produce disposable magnetic recording media which is intended for one write operation, followed by only a few read operations. The head sits on the card and contains a quantity of ink at ambient pressure and temperature. As the head and card move relative one another, the ink is subjected to a shear force, and a bottom surface layer of the ink is drawn into a trailing wall of the head, which wall contains a metering orifice. This orifice is of gradually increasing cross-section. That is, the orifice's entrance area is smaller than is its exit area. In this manner, the ink is subjected to a coating interface through which the ink experiences a reduction in hydrodynamic pressure, and a decrease in velocity, as the volume of the coating orifice increases. As a result, the viscosity of the ink increases as the ink progresses through the coating orifice.
|
