Patent GB-822962-A (GB)
Title: Improvements in or relating to the treatment and washing of sheet material
IPC: B29D7/00
Filed: 1957-03-08
Abstract: Apparatus for washing or treating a web F comprises tanks 15, 16 containing wash liquid, rolls 11, 12, 13, 14 submerged within the tanks, transfer rolls 17, 18, 19, 20 above the tanks, web-treating means comprising a number of elongated L-shaped angles 24 each composed of a substantially horizontal surface and a substantially vertical surface disposed at least four inches above the liquid level in the tanks and transverse to the ascending path of the travelling web, scraping means mounted on the substantially horizontal surface of each angle and means for mixing and reapplying a portion of the removed liquid to the surface of the travelling web at a level above the scraping means, the said web-treating means being arranged in pairs, one on each of the path of the web and at different levels. The scraping means may comprise a blade 25 having a width at least <PICT:0822962/IV(c)/1> <PICT:0822962/IV(c)/2> <PICT:0822962/IV(c)/3> equal to the width of the web mounted on the substantially horizontal surface of each angle and extending at least 0.25 inch beyond the edge of that surface.  Mixing and reapplying means may p  comprise a three-sided triangle formed by fastening dams 28 to each side edge of the blade, in combination with the vertical surface of the angle. The angles may be tilted upwardly to form an angle between the blade and the horizontal plane of up to 15 degrees, and they may be so disposed that the blades displace the travelling web 1-2 inches from a vertical path, as shown in Fig. 3.ALSO:A web of film travelling in a zigzag path in substantially vertical legs has a layer of liquid formed on each side, by applying treating or washing liquid at the bottom of each leg, and the layers are removed by bringing the web into contact with one or more pairs of scrapers on some or all of the ascending legs, the members of each pair being at different levels and bearing against opposite sides of the web and the arrangement being such that part of the liquid removed from the web is reapplied above the point of removal before the liquid is finally removed from the web.  The web may be a regenerated cellulose film travelling at a speed of 100 yards per minute.  Suitable apparatus comprises tanks 15, 16 containing wash liquid, rolls 11, 12, 13, 14 submerged within the tanks, transfer rolls 17, 18, 19, 20 above the tanks, web treating means comprising a number of elongated L-shaped angles 24 each composed of a substantially horizontal surface and a substantially vertical surface disposed at least 4 inches above the liquid level in the tanks and transverse to the ascending path of the travelling web, scraping means mounted on the substantially horizontal surface of each angle and means for mixing and reapplying a portion of the removed liquid to the surface of the travelling web at a level above the scraping means, <PICT:0822962/IV (a)/1> <PICT:0822962/IV (a)/2> <PICT:0822962/IV (a)/3> the said web treating means being arranged in pairs, one on each side of the path of the web and at different levels.  The scraping means may comprise a blade 25, having a width at least equal to the width of the web, mounted on the substantially horizontal surface of the angle and extending at least 0.25 inch beyond the edge of that surface.  Mixing and reapplying means may comprise a three-sided trough formed by fastening dams 28 to each side edge of the blade, in combination with the vertical surface of the angle.  The angles may be tilted upwardly to form an angle between the blade and the horizontal plane of up to 15 degrees, and they may be so disposed that the blades displace the travelling web 1-2 inches from a vertical path as shown in Fig. 3.