Continuous gradient dyeing of plastic ribbon
AssigneeAmerican Hoechst Corporation
InventorRobert Weis
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Abstract
There is described a process for producing, in a continuous manner, a gradient dyeing across the width of a long strip of a plastic sheet and an apparatus used therefor. In a preferred embodiment of the invention, the orientation of the plastic strip is maintained substantially constant during the passage through a dye bath, and the dye liquid level is repetitively varied by use of a liquid level control means. This invention is particularly useful for making gradient-dyed plastic sheets which in turn are used for making sunglass lenses.
Claims8
A process for producing in a continuous manner a gradient dyed plastic ribbon, wherein said ribbon is passed longitudinally through a dye bath by a ribbon drive means, the plane of said ribbon is maintained at a substantially constant angle with respect to the dye bath surface during the residence of said ribbon in the dye bath, the liquid level of the dye bath is repetitively varied with time between two pre-determined levels by a liquid level control means and the overall orientation of that portion of the ribbon which is undergoing the dyeing process in the dye bath is substantially level from one end to the other.
Dependencies are inferred from the claim text.