US 3079699 A
Description (OCR text may contain errors)
March 5, 1963 H. P. FRY, JR 3,079,699
WEB HUMIDIFYINC METHOD Filed Oct. 27, less 3,979,699 WEB HUMIDEFYWG METHQE) Horace P. Fry, .in, West (Ihester, Pa, assigns: to American Viscose Corporation, Philadelphia, Pa, a corporation of Delaware Filed Get. 27, 1958, Ser. No. 79,752 2 Claims. (Cl. 34-43) The present invention relates to the application of moisture to sheet materials, and more particularly to a method for humidifying a traveling web of sheet material.
During the manufacture, storage, conversion and use, sheet materials, as for example paper, films, fabrics, etc., undergo a considerable loss of moisture. With conventional and known procedures, restoration or" moisture into the sheet material is achieved by exposing the same to humid air under atmospheric pressure and at an elevated temperature of about 212 F. or below. Increasing the pressure on the humidifying air is not generally possible with existing equipment, while elevating the temperature of the moist air tends to superheat the same and introduces a condition wherein the moisture is actually extracted from the sheet material. Accordingly, the primary object of this invention is to provide an improved method for restoring moisture to traveling sheet materials.
Another object is the provision of the method for humidifying sheet materials uniformly and at a greater speed than heretofore possible.
Still another object is to provide an improved humidifying method wherein a sheet material is subjected to vaporized moisture which is under a pressure greater than atmospheric pressure.
A further object is the provision of a humidifying method wherein moisture is heated while being confined against a sheet material whereby the moisture is transformed into a. vaporous condition and migrates into the sheet material under increased pressure as it expands.
These and other objects and advantages of the invention will be apparent from the following description and accompanying drawing in which:
FIGURE 1 is a shortened vertical section taken longitudinally of the apparatus employed in the method of the present invention;
FIGURE 2 is a vertical section taken longitudinally through a portion of a roll employed in the apparatus shown in FIGURE 1;
FIGURE 3 is an end view of a single roll illustrating a modified arrangement for applying the moisture to a sheet material;
FIGURE 4 is a view similar to FIGURE 3 means for applying moisture to a roll surface;
FIGURE. 5 is a view similar to FIGURE 4 illustrating a modified roll construction; and
FIGURE 6 is an end view of a roll having a porous peripheral surface which is capable of passing a humidifying atmosphere.
In general, application or restoration of moisture to sheet materials in accordance with the present invention is achieved by trapping or confining moisture between the sheet material and a heated surface, whereby its vaporization and accompanying expansion causes the same to migrate into the sheet material under a pressure greater than atmospheric pressure. Following this humidifying treatment the sheet material is cooled to condense the moisture contained therein.
With reference to FlGURE l of the drawing, the sheet material to be humidified, such as illustrated at 15, is passed over and is advanced with a series of spaced rolls 17 which are maintained in a heated condition so as to showing EQQ vaporize moisture applied to the sheet material, as by nozzles 19. Pairs of guide rolls 21 and 23 maintain the sheet material 15 engaged with substantial portions of the peripheries of the rolls 17 and, in addition, cooperate with the rolls 17 to prevent the escape of moisture as it expands during its transformation into a vaporous state. The rolls 17 are driven as indicated by arrows in FIG- URE 1 by any suitable means, not shown, and the sheet material 15 is maintained under sufficient tension so as to msure that its longitudinal edges are pressed snugly against the roll surfaces. From the structure and procedure thus far described, it will be apparent that the moisture is effectively trapped or sealed against escape while the sheet material travels with the rolls 17 and will therefore migrate into the sheet material under increased pressure as it expands during its vaporization.
As the sheet material 15 leaves the last of the series of rolls 17, it is passed about a guide roll 25 and over a chill roll 27 w ere it is cooled to condense the moisture carried therein. To contain the hot humid atmosphere which is evolved during the humidifying procedure, the series of rolls 17 are enclosed within a housing or chamber 29 having elongated slots 31 and 33 in its opposite end walls to permit the continuous passage of the sheet material 15.
The rolls 17 are of known construction, each being provided with concentric hollow shafts 35 and 37 through which a heated fluid, as for example hot water, is circulated to maintain the rolls at a desired elevated temperature. In a similar fashion, the chill roll 27 is also formed with concentric hollow shafts 39 an 41 through which cool water or chilled brine is circulated. It will of course be understood that other heating and chilling surfaces, such as endless metallic belts, may be substituted for the rolls described above, and that electrical heating and air cooling may be employed in lieu of circulating fluids.
if desired, the longitudinal edges of the sheet material 15 may be more snugly held against the surfaces of the rolls 17 by means of pairs of cooperating endless belts 43 which, as shown in FIGURE 1, are trained over a series of rolls or pulleys 45, at least one of which is driven by suitable means, not shown. The endless belts 43 are not intended to advance the sheet material 15 but serve primarily as a means for sealing the longitudinal edges of the sheet material to prevent the escape of moisture during its expansion. The use of endl ss sealing belts 43, of course, reduces or eliminates any tendency for the sheet material 15 to tear or stretch, as when the sheet material is subjected to undue tension, and is of special importance when fragile sheet materials are being treated.
To achieve a greater degree of humidification and/or to increase the rate of humidification without a corresponding increase in the size of the structure, the sheet material may be chilled after leaving selected or each of the rolls 17, thus subjecting the sheet material to alternate heating and cooling stages. This cooling of the sheet material may be accomplished by a dip roll 4-7 which applies cool water from a tank 49, or alternatively an internally cooled chill roll, similar to the chill roll 27, may be employed. It will be understood that chilling the sheet material 15 during its passage through the chamber ER is not essential to the satisfactory practics of the present invention, and therefore only a final cooling of the sheet material, as by the chill roll 27, need be employed.
In lieu of applying a mist of moisture to the sheet material and the peripheries of the rolls 17, as is accomished by the nozzles 19, moisture may be applied to the sheet material in a manner as shown in FIGURE 3 wherein a dip roller 51, turned by the advancing sheet material, delivers water from a tank 53 to the sheet material as it travels over the guide roll 21. A further modification is illustrated in FIGURE 4- wherein liquid from a tank 55 is applied directly to the periphery of a roll 17 by a dip roller 57 which engages and turns therewith. The structure illustrated in FIGURE is generally similar to that shown in FIGURE 4 with the exception that the roll 17 is provided with an outer absorbent covering 59, as for example of felt. One particular advantage of this last-mentioned arrangement is that the absorbent covering 59 quickly absorbs the moisture applied by the dip roller 57 and thus there is no tendency for any moisture to be squeezed from the sheet material as it travels between the roll 17 and the guide roll 21.
The'roll structure 61 shown in FIGURE 6 difiers from the heated rolls described above in that the roll61 is provided with a porous peripheral surface 63 formed, for example, by a mass of powdered metal particles sintered or otherwise bonded into an integral cylindrical unit. With this'arrangement, the liquid to be vaporized may be applied to either the sheet material 15, as shown in FIGURES 1' and '3, or to the roll periphery, as shown in FIGURE 4, whilera heated medium, as for example air, is delivered through a hollow shaft 65 andlpasses through the porous roll periphery. It is preferred, however, 'to apply the moisture to the sheet material in a heated'condition directly through theporous'wall 63 of the roll, as for example in'the form of wet'steam under pressure. This procedure insures that the applied moisture has no opportunity to escape" before it is further vaporized as the sheet material'lS travels with the heated wall of the roll 61. I
The degree of sheet material humidification isof course controlled by regulating the number of heated rolls employed, the temperature of the heating and cooling surfaces or mediums, and the rate of advancement of the sheet'material, and thus the procedure described can be modified to best suit the particular material being treated without departing from the spirit and scope of the invention. I
The present invention may be used in treating'a'variety of sheet materials, as for example fabrics, papers and films; The compact and simple nature of'the humidifying apparatus here described renders it highly suitable for use on printing machines in treating papers or 'films, as for example cellophane, which have become over-dry and brittle during the ink-drying stages. Further, the novel method of maintaining the humidifying moisture under pressure only While this moisture is contained between the sheet material being treated and the surfaces of the heatedrolls results in a rapid and uniform humidification of the sheet material and, in addition, reduces or eliminates any tendency for the humidifying atmosphere to be forced out from the enclosing chamber through the slots 31 and 33. I
It is seen from the above description that the objects of the invention are well fulfilled by the method described. The description is intended to be illustrative 4 only and it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.
1. A method of humidifying a continuous traveling web of sheet material including the steps of applying a humidifying liquid to one side of the traveling web progressively in a longitudinal direction thereof, engaging successive portions of said one side of the traveling web with an endless heated surface to vaporize the liquid applied thereto, pressing transversely extending areas of said successive portions of said web against the heated surface at longitudinally spaced areas thereof, urgingzthe longitudinal edges of said web extending between said longitudinally spaced areas into snug contact'with the heated surface to thereby prevent the escape of the liquid as his vaporized and expands whereby the vaporized liquid is caused to enter into the successive portions or the web under a pressure greater than atmospheric pressure, and cooling the humidified web. v
2. A method of humidifying a continuous traveling web of'sheet material including the steps of applying a humidi-' tying liquid to one side of the traveling webprogressively in a longitudinal direction thereof, engaging successive portions of said one side of the traveling web with a heated surface to vaporize the liquid applied thereto, pressing transversely extending areas of said successive portions of said web against the heatedsurface at longi tudinallyspaced areas thereof, urging the longitudinal edges of said web extending-between said longitudinally spaced areas into snug contact with the heated surface to thereby prevent the escape of the liquid'as it is vaporized and expands whereby the vaporized liquid is caused to enter into the successive portions of the web under apressure greater than atmospheric pressure, and. cooling the humidified web.
References (Zited in the file of this patent UNITED STATES PATENTS