GB992437A - Process and apparatus for applying film-forming liquid compositions to webs - Google Patents

Abstract

992,437. Web coating apparatus. E.I.DU PONT DE NEMOURS & CO. March 25, 1963, No. 11761/63. Heading D1L. In a process for applying a film-forming liquid composition to webs on the overflow principle in which a film of the liquid is formed by such liquid overflowing over a weir, the said weir is a roll, the liquid being supplied to one side of such roll and overflowing over the top of the roll to form a film flowing down the other side of the roll, and the web is moved past a position on said other side of the roll below the top thereof so that the liquid composition is taken up from such film and applied to the web. The apparatus shown comprises a vessel having an entry section 1 separated except at the bottom from an adjacent section 9 which in turn is separated by partition 10 from a third section 6 containing a cleaning liquid. A roll 3 dips into the cleaning liquid and adjacent thereto is a guide roll 11. Partition 10 is angled at the top to define a drying zone 7 and a chamber 5 is provided in which a reduced pressure can be maintained. In use coating liquid is fed into section 1 and rises in section 9 into contact with roll 3 until it reaches overflow point 2. It then flows in a thin film to the line of application 4 between rolls 3 and 11 where it comes into contact with the film base 12 and is applied thereto. The roll 3 may be stationary in which case reduced pressure may be applied to chamber 5, for application of liquid beyond a specified viscosity and film thickness, to effect adequate penetration of the liquid into slit 4. Alternatively the roll 3 may be rotatable. After application of the liquid roll 3 is cleaned in the bath 6 and dried in drying zone 7. The vessel and roll 3 may be provided with heating means.