| 摘要 |
<p><FORM:0842879/III/1> In a process for coating fibrous sheets 9, e.g. printed cards, envelopes, book jackets, in which the cards are coated with a liquid comprising a plastic material dissolved in a volatile thinner and are dried, e.g. by infra red heating, to evaporate the thinner and leave the plastic as an adherent film on the cards 9, the cards 9 are chilled immediately after drying while the cards 9 are tacky to eliminate the tackiness and harden the coating. The cards 9 are fed singly through rubberfaced rollers 11, 12, which coat them on both faces, the roller 11 dipping in a trough 14 of varnish or lacquer 13 having a vinyl chloride base, the lacquer being circulated through a line 17 by a pump 16. The coated cards 9 are carried by an endless conveyer 24 beneath a suction fan 33 to remove solvent vapours, through a drying tunnel 34 equipped with infra red heaters 35, 36, through a cooling tunnel 40 through which atmospheric air is passed, and through a chilling tunnel 43 through which air chilled by a refrigerator 44 is circulated. Adjacent tunnels 34, 40, 43 are separated above and below the conveyer 24 by flaps 49, 50. Where thick cards 9 are to be coated, a valve 21 is opened to ensure that lacquer is delivered directly to the roller 12, the rollers 11, 12 being slightly spaced to accommodate the cards 9. The conveyer 24 comprises a pair of parallel chains between which extend transverse bars which are oval in section and which carry a series of sharp, upstanding pins which support the cards 9. The conveyer may travel at 60 to 150 feet per minute, and, where the solvent is amylacetate and xylene, the tunnel 34 is at 250 DEG F. receiving 650 cubic feet air per minute, while 2000 cubic feet air per minute through the tunnel 40 reduce the cards 9 from 150 DEG F. or 170 DEG F. by 25 DEG F. or 30 DEG F. In the tunnel 43 800 cubic feet air per minute at 30 DEG F. reduces the cards 9 to about 70 DEG F.</p> |
