GB647886A - Method and apparatus for coating webs - Google Patents

Abstract

647,886. Coating webs. WALDRON CORPORATION, J. Feb. 19, 1947, No. 4772. Convention date, March 13, 1946. [Class 140] A web, e.g. of paper, is coated by first applying an excess of coating material and then to remove excess coating, impinging a jet of air against the web at such an angle that the component of force tending to drive the composition into the web exceeds that tending to blow the composition backwardly, means being provided adjacent the point of impingement to intercept atomized coating material and prevent its return to the web. A web W, Fig. 1, prewetted by the coating material or a solvent or thinner applied by a roll 15, and doctored by a knife 16, is coated by an applicator roll 17, subjected to an air jet N as it passes round a platen roller 20, and thence passes to a drier or other apparatus through a suction box A containing a travelling perforated rubber apron 22. The air jet N, Fig. 2, comprises a horizontal tube 25 parallel with the roller 20 and having elbows 26 journalled in the machine frame 28 to allow the jet to be rotated between angles of 45 and 90 degrees to the web, bolts 32 and 34 moving in slots 33 and 35 to limit the rotation and serving to hold the jet in any predetermined position. The tube 25 is also rotatable with respect to the elbows 26, a stop lug 57 formed on the tube 25 being engaged by a screw 58 for fine adjustment and to allow the nozzle tn be swung away for cleaning and returned to its original position, and a locking screw 60 on the tube 25 engaging a lug 61 on the machine frame for holding the nozzle in its operative position. The nozzle tube 25 comprises a radial flange 36 which may be integral with the tube and with which cooperates a movable plate 37 to form the nozzle slot. The plate 37 has a ridge 39 pivoting in a groove 38 in the wall of the tube 25 and is spring-urged against a micrometer adjusting screw 42 which may be calibrated for the width of the nozzle slot. A baffle B deflects backward the atomized coating composition and comprises a triangular bar 45 slidably mounted on a shelf 46 on the machine frame. The bottom of the bar 45 is slotted to receive bolts 47 which retain it in position after adjustment by screws 48. The bar 45 has a ridge 49 below the line of impact of the jet, and the inner wall 50 is smoothly curved to further deflect mist from the nozzle slot. A feeding comb 65 operated by a hand lever 68 and having tines 67 is provided for feeding the web over the roller 20.