US2920399A - Apparatus for finishing cellophane - Google Patents

Description

Jan 12, 1960 H. P. FRY, JR

APPARATUS FOR FINISHIN G CELLOPHANE 3( |.ll`l l Il O l d) t 5 5 w a s f mm llfllirll a 2 Q 8 5 4 5 8 3 I` 3 m 5 l C. 5 M EL* 9 3 k e 4 v.; lv /7 3 O 7. ...v 7 6 3 7, 7 7 A 5 5\ 5 iw f M M m 6 (1:: l -Ill :lill 5 l l l l l 1 l w Ill l lllllllllllll |||,-|||.I|I .1| Ff 1111 |11' l -.2 mw 7 VIL 5 1|! 1 l I i w NNW. ----IIuUml. F d ull l llll e lul I. I l Ill Illll. Il .l F 9 5 H. P; FRY, JR

APPARATUS FOR FINISHINC CELLOPHANE Jan. 12, 1960 Filed Feb. 29, 1956 5 Sheets-Sheet 2 Jan- 12, 1960 H. P. FRY, JR 2,920,399

APPARATUS FOR FINISHING CELLOPHANE Filed Feb. 29, 1956 5 Sheets-Sheet 3 Jan. 12, 1960 H. P. FRY, JR 2,920,399

APPARATUS OR FINISHING CELLOPHANE I Filed Feb. 29, 1956' 5 Sheets-Sheet 4 f? LRVN" f @CUL g ---lle' H8 f g )Civ3 Jan. 12, 1960 H. P. FRY, .JR 2,920,399

APPARATUS FOR FINISHING CELLOPHANE Filed Feb. 29', 1956 5 Sheets-Sheet 5 United States Patent O APPARATUS FOR FINISHING CELLOPHANE Horace P. Fry, Jr., West Chester, Pa., assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application February 29, 1956, Serial No. 568,532

13 Claims. (Cl. 34-159) This invention relates to `an apparatus for drying sheet material. More specifically it relates to a novel and improved apparatus for drying a freshly coated cellophane sheet.

The manufacture of cellophane sheet or yfilm by the continuous extrusion of an alkaline viscose solution through a slit into an acid coagulating bath is well-known. The coagulated film is drawn from the coagulating bath and through a series of treating baths wherein the film is successively regenerated, washed, desulfurized, washed, bleached, Washed, dyed if desired, and finally softened with plasticizer. The purified wet sheet is passed over and under a number of heated rollers and finally wound up to produce what is known as a mill roll. To render the cellophane moisture-proof it is subsequently coated with a moisture-proofing lacquer by unrolling the mill roll through a lacquer solution of, say nitrocellulose in a solvent such as acetone, toluene, or alcohol. The final step is the drying of the lacquered sheet to expel the lacquer solvent and recover it for re-use. vThis general process is described in U.S. Patent No. 1,826,697.

Since this last drying stage must be a continuous process in order to keep up with the continuous coating of the film it is necessary for the film to move through a considerable linear distance in contact with ,air or other drying uid before the lacquer coating is non-tacky or dry. In addition it is desirable to provide for a rehumidifying stage following the lacquer-drying step as this step may remove from 2-3% moisture from the cellophane. This moisture loss should be replaced and perhaps even increased to a total of from 6-7% in order to give the finished material a smooth hand and make it flexible and non-brittle. It is evident that a considerable volume of plant space could be occupied by the drying and humidifying apparatus.

The prevailing practice is to advance the sheet through the drying step in a generally horizontal direction. The result is that a considerable distance separates the unwind or intake end of the film from the wind up or outlet end. In one plant, for example, this space is over 100 feet. A span of this length requires at least one man at each end which necessarily results in long distance Signalling between the two men as, for example, by hand signals or buzzers. Much delay and wasted manpower occurs in correcting faults; e.g., one man may have to resort to the help of an operator of an adjacent machine to make a correction at his end of the dryer, while the man at the other end stands idle. A similar situation ccurs during the initial lacing of the sheet through the dryer as will be explained later. It would obviously be desirable and an economic saving if the dryer could be so designed that the unwind and the wind up ends were close enough together to eliminate the difficulties mentioned above.

Accordingly the principal object of the present invention is to provide a novel land improved means for drying a continuous -lm or sheet. A more specific object is to provide an improved cellophane dryer and humidifier having the unwind end suiciently near the wind up end so that one man can observe and be able to make corrections on both. A further object is the provision of means having the aforesaid features which will permit uniform impingement of drying or humidifying gas against the sheet gas being withdrawn from windup ends are on opposite sides of a common accessv aisle. By using a multiple pass arrangement itis possible to advance the sheet through a considerable linear distance within a comparatively small cubic space. Further, arranging the sheet passes along predominantly vertical planes, the bulk of the structure may extend in a vertical direction, instead of horizontally, thereby economizing on construction costs and the expense of land. By designing the dryer and humidifier so that it spans or bridges an access aisle, it is not only possible for one man standing in the aisle to observe the entire operation, but also allows trucks to unload the mill rolls and pick up finished rolls from lthe windup side of the aisle.

In the drawings,

Fig. 1 is an elevational view of the entire coating, ing, and humidifying apparatus of the present invention,

Fig. 2 is an elevational view, partly in section, of the coater and the first zone of the dryer shown in Figure 1,

Fig. 3 is a horizontal section taken along the line 3 3 of Fig. 2, showing the air circulation pattern,

Fig. 4 is an isometric View of a portion of the structure of Fig. 3, showing louvers and ports for controlling air recirculation,

Fig. 5 is an enlarged detail of a louver shown in Figs. 3 and 4,

Fig. 6 is an elevational view, partly in section of the upper or zone II dryer of the structure shown in Fig. 1,

Fig. 7 is a section taken along line 7 7 passing through the humidifier zone III of Fig. l,

Fig. 8 is a perspective view of one side of the humidifier of Fig. l, and Y Fig. 9 is an enlarged detail of the encircled portion 9 of Fig. 8.

showing the drainage system employed therein,

Referring to the drawing, the lilm or sheet is delivered to an unwind stand 1 from the casting machine in thousand pound mill rolls, one of which is indicated atV 2.- The unwind stand is designed to carry three cylinders, thev roll being unwound for lacquering, another roll ready to be rotated into the place of the first and spliced on when the first one is stripped, and an empty core 3 which is ready to vbe unloaded. In one specific modification the sheet is 62-68 inches wide; the mill roll is 16 inches'in diameter and weighs about 1,000

3 is about 8 inches in diameter.

The film or sheet, shown at 5, is unwound around spring-mounted dancer roll 6, passed around three or more and then enters preand enters coating head 13. The sheet 5 is passed down through a lacquer pool 12in dip pan '14, around a roller. 15 immersed therein, and up between squeeze rolls 16,

16a the first of a pair of dryers, indicated generally as zones I and II.

The pressed sheet advances through zones I and II vertically unsupported except for a pull roll 51 at thev top of zone II. Zone I includes a vertically elongated .y tower 20 of rectangular cross-section and having a taperpounds, while the core` Rolls 7 tension the Sheet as it passes ing top and bottom. 'Essentially it is an elongated drying oven wherein the bulk of the solvent is evaporated from the lacquer on the sheet. Air enters zone I through pipe 31 which is dampered at 31a, and feeds into duct 25, with some additional air entering around access doors 24. The air from both sources is pulled through duct 25 andheater 26 by means Yof blower 22 and recirculated through duct `23. Acertain amount of solvent-laden air is drawn from the system through absorber 27 and passed to a recovery unit 28, .wherein the solvent is recovered for reuse indip tank'ld. Conventional separation means may be employed here; hence the details of the apparatus need not be illustrated. The air supply to zone I may be'supplemented by air withdrawn from zone II through conduit 30 and admitted to absorber 28 or by-passed to duct 25, depending on the setting of dampers 32, 33.

Zone II is similar to zone I in that it comprises a vertical drying kiln 35 to which air is supplied partly from inlet pipe 38, dampered at 33a and opening into duct 40, and partly through air leaking into the system as around access doors 44. This combined air supply, along with that withdrawn through exhaust duct 39, is pulled in series through heater 41 and humidifier 42 by means of a blower 36, and returned to zone II by duct 37. A portion of this air may be exhausted from the system through exhaust'line 37a depending on the setting of damper 37b. Blowers 22, 36 are driven by motors 65, 46 respectively. Zone II has the added flexibility of being used as a humidication zone, as will be explained later.

From the top of zone II the sheet next is pulled under a combination spreader and sheet aligning roll 50, over pull roll 51, and under nip roll 52 cooperating therewith. Nip roll 52 is rubber covered and serves to press the sheet against the pull roll drum so that the latter can pull the sheet with a minimum of slippage.

In a typical vembodiment pull roll 51 is approximately 18 inches lin diameter, and is made from chrome plated steel designed to be chilled with water. Pull roll 51 is the first member to actually pull the sheet, with the tension `in 'the vsheet from this Vpoint back down through zones I and II, the squeeze rolls, the dip pan 14, and prehumidier V8 being regulated by the resistance put on tension rolls 7. The mill roll spindle 3 in the unwind stand 1 has a small friction brake which is manually controlled to'put some resistance on the sheet as it unwinds and this resistance adds to the resistance of the tension rolls 7 to further increase the tension in the sheet passing through the'tower. This tension is far below the strength limits of the sheet and must not be a magnitude that would cause wrinkles to come into the sheet, an ever present possibility.

From Vpull roll `51 the sheet passes alternately over and under rotating rolls 53 which alternately support and deflect the sheet so as to reduce flutter as it travels horizontally from the vtop of zone II to the humidifier, zone III. After leaving the last of rolls 53 the sheet passes over a second pull roll 55 equipped with aligner roll 54 and cooperating nip rolls (not shown) in the manner of first pull roll 51, and enters the humidifier. The function of this section is to humidify the lm and remove the last traces of coating composition.

Zone III consists basically of a group of vertical columns, approximately 50 feet high, through which the sheet passes alternately up and down, the number of passes being'sufcient to effect hydration of the sheet to'the desired degree, preferably 6-7% moisture content. In the drawing, five passes are shown but it should be understood that this number may be increased or dccreased according to the degree of hydration desired.

'The sheet changes direction at the top of each upward pass by means of larger pull rolls 57, 59 with their matching aligner rolls 56, 58 respectively, and at the base of the downward passes by means of pull rolls 62, 63 and 66, 67 each set cooperating with aligning rolls 61 and 65 respectively. Pull rolls 57, 59 are about 2l inches in diameter, as compared to '18 inches diameter for roll 55, and are water-Cooled so as to chill the sheet and thus permit increased moisture absorption during the next pass.

Broadly, the gas circulation through zone III is effected by a pair of motors 70,70' which drive blowers 71, 71 for pulling humid air (whichenters through apertures 60 at the top of zone III) through ducts Y73 and 74, '74', and recirculates it through yheaters 75, 75', humidiflers 76, 7 6', and then back into zone III through inlet ducts 72, 72. Recirculation is at the ratefof 20,000 c.f.m. Dehumidied air may be exhausted into Ythe atmosphere in the proportion necessary through vents 78, 78', by adjustment of dampersS, 80. Access Vdoors indicated at 81, 82 permit access to each pass. As the sheet emerges from the bottom of the last column it passes around aligner roll 84 and then laces around the last pull roll unit 85, which consists of yfour rolls, approximately l foot in diameter and water-cooled so as to cool the sheet down to room temperature before it is wound up on rolls. The sheet then is passed between a small roll 87 and a rubber-covered nip roll 88 which are driven to feed the sheet forward to the wind-up mechanism where it is wrapped into a roll 90 similar to roll `2 at the unwind. The core of this roll is motor driven at a controlled rate so `that the tension of the sheet as it is wound up is held within specified limits. Additional cores are indicated 'at V91, 92. The sheet is wound up on roll 90 until a weight of about 1,000 pounds is obtained. The wind-up 'mechanism is rotated so that the full roll is rotated towards the operator standing inthe aisle which brings up van rempty core 92 into Vwinding position. The operator breaks the sheet by snippingthe ends with his fingers and tucking the end around vthe empty Vcore so that the sheet wraps on itself.

Dip pan 14, as shown in somewhat more detail in Fig. 2, is adjustable vertically and can be lowered on hydraulic cylinder '14a vto the bottom position (shown in dotted outline) when-the sheet is rst wound under roller 15 and up between 'squeeze rolls 16, 16a. In this way the operator can avoid putting his hands in the lacquer solution. Preferably dip pan 14 is all aluminum. Squeeze rolls 16, 16a are of hardened alloy steel, chrome plated, precision ground, and accurately positioned to limit Vthe clearancethrough'whichithe-sheet passes to about 21/2 thousandths of an inch. Roll 16 has its journal box bolted to the frame of the coating head while roll 16a has slidable journals which are adjustable to permit extremely ne movements of the roll so that accurate spacing can be maintained between the two. From rolls 16, 16a the sheet passes between two pairs of small diameter rolls, known as doctor rolls indicated at 1'7; these are staggered so that the sheet describes a slight zig-zag path in passing between them. Doctor rolls 17 run counter to the direction of sheet travel at a surface speed the same as or less than that of the sheet, depending on coating conditions. Their purpose is to smooth out minute irregularities in the coating as it comes from the squeeze rolls.

Among the ingredients of the coating composition used in coating head 13 may beincluded cellulose derivatives such as cellulose esters and ethers, resins, both natural and synthetic, plasticizers, such as tricresyl phosphate, and moistureproofing agents, such as paraiiin wax.

The internal details of zone I are well illustrated in Fig. 2, especially in conjunction with Figs. 3, 4, and 5. Dryer 20 contains a metallic outer shell 100, approximately square in cross-section, and two duplicate units on each side of the sheet. In a typical embodiment it would be approximately v25 feet high, 7-71/2 feet square, aluminum-lined Yandinsulated. 'The unit whichris numbered on ,the drawing comprises a hot air inlet manifold or `header 101 adjacent the vpath lof the sheet, andan exhaust manifold or header `,102 adjoining it on-the .out-

side. A common wall 104 separates the two headers. Each hot air manifold 101 is provided with a series of horizontal parallel nozzles 106 running the full length of the manifold and spaced uniformly up the sides of the column in the nature of shelves.l Preferably the nozzle outlet 107 (Fig. 4) is simply a horizontal slot aimed `downward about 60 to the vertical.

As shown in Fig. 3, inlet duct 23 extends around both ends of the dryer 20 and feeds into inlet manifolds 101, from which the air is forced directly outwardly through nozzles 106 against the sides of sheet 5. Deflecting from the sheet the solvent-laden air travels laterally through the trough-shaped spaces between the rows of nozzles, around the ends of manifolds 101 through screens 110 and louvers 111, and into outlet manifolds 102,

From outlet manifolds 102 the air returns through ducts 25, 27; duct 25 returns the air to the heater 26, fan 22, etc., for recirculation; duct 27 takes a portion of the exhaust gas directly to solvent-recovery means 28, as stated in connection with Fig. 1. The air recirculation in zone I should be at the rate of about 15,000 c.f.m.

n Screen 110 runs the full length of both zones and is designed to trap fragments of sheet or, in the case of a break in the sheet, to prevent long lengths of sheet entering into the air system. The screen can be a coarse mesh type, say 1/2 inch mesh, of aluminum. Louvers 111 are metal sheets extending from the end ofthe inlet manifold 101 to the adjacent corner of the outer shell 100.

As further illustrated in Fig. 5, louvers 111 include an orice 112 which can be set to the desired opening proper positioning of a vertically adjustable cover 113. The outer edges of louvers 111 are secured to the inner wall of the housing `by bolting them to the abutting ridge 99 of upright corner braces 98, as illustrated in Fig. 4.

A pair of dampers 114, 114a (Fig. 2) are located in outer manifold 102 between the adsorber duct connections and the recirculating fan suction ductconnections. These dampers can be turned to more or less control the air ow to the adsorbers as will be explained later. Another pair of dampers 115, 115 permit solvent-laden air that leaks into the base of zone I from the coating head 13, to be carried directly into outlet duct 27. Due to the vertical arrangement of zones I and II a stack effect is inherent so that the air from coating head 13 tends to rise as in a chimney. The action of dampers 115, 115 effectively prevents such air from reaching the drying zone.

At the level where the sheet passes from zone I into zone II (Fig. 6) an access door 120, opening by swinging up and out as indicated by the dotted line, covers two nip rolls 123, 124 to steady the sheet and to reduce the amount of uttering experienced when blowing air onto the lm. These nip rolls can only be used if the lacquer has dried to a tack-free condition. The zone II air duct.l differs from that of zone I in that it contains a humidifier 42 adjacent the heater 41; this permits the option of airdrying as in zone I or humidifying to return to the sheet the moisture driven olf during the drying operation in zone I. To implement this option the return manifold 37 of zone II is equipped with exhaust line 37a opening directly into the atmosphere. In addition, the return conduit 30 connects either to absorber 28 or to duct 25 (Fig. l). This arrangement permits the efluent air from zone II to be exhausted in one of three ways as follows:

(1) If the eluent air contains little or no entrained solvent it is vented to the atmosphere at 37a. This will be the case where drying has been completed in zone I, and zone II is functioning as a humidifier.

' (2) If zone II is used as a dryer, the effluent air can be returned through ducts 30 and 25 as make-up air for zone I, thereby conserving its heat content for reuse. The air -recirculation rate in zone II is similar to that of zone I, e.g. 15,000 bc.f.m.

(3) If zone II is used as a dryer and the euent air is not needed as make-up air for zone I, it is routed directly through line 30 to the absorber 28 for solvent recovery, a reasonable rate being 8,000 c.f.m. maximum.

At the top of zone II is an enlarged seal chamber bounded on two sides by two rows of nned pipes 125, 126 which are steam heated to warm any air entering through aperture 127, thus avoiding condensation in this area. Otherwise the mixing of the room air with high humidity air in zone II would lower the dew point of the mixture sutliciently to cause moisture droplets to forml at the interface. The dampers 129, 130 are regulated to4 pull olf air which comes up with the sheet beyond the range of the nozzles, and hence are necessarily opened wide enough to draw in some room air through It-he aperture 127.

Dampers 117,117 at the top of zone I and dampersr 118, 118 at the base of zone II (Fig. 6) function in the same manner as dampers 115, at the base of zone I. These dampers are designed to open when the access door is open so as to draw olf any air coming in the doorway.

Sheet aligning roll 50 at the top of zone II can be any device of .this type known in the prior art. In one embodiment the aligner roll is mounted on a frame having a pivot located in the center of the sheet path and is oscillated through a vacuum cylinder which is controlled by a conventional vacuum sheet edge sensing `device. The aligning roll 50 also functions to iron outthe sheet before it passes over the pull roll immediately followingv r The purpose of zone III, the humidifier, is to increase the moisture content of the sheet suciently to give it the proper physical characteristics, e.g., to reduce its brittleness, before it is wound up. This zone is somewhat larger in cross-section than zones I and II. The distribution ofr air-through this zone is similar to that of zones I and I-I,l although there are some differences. The humidifier is housed in a metallic shell which, as seen in Fig. 9, consists of an inner metallic liner 140a such as aluminum, an outer sheath or hide 140b, and an intermediate layer of insulation 140C. Housing 140 is divided into a series of vertical headers 142, 143, 144, 145, 146, andV 147 (Fig. 7). This number would, of course, be reduced or increased if the number of passes of the sheet were reduced or increased. The headers 142, 147, which are adjacent the wall of housing 140, have nozzles 150, 150j respectively, on their inner side, as is the case with those in zones I and II, the wall 140 in this case forming theback sides of the header. Internal headers 143-146 have nozzles 151 on both sides facing the sheet. These nozzles are pointed downward in the manner of those in zones I and II. Each of these headers can be considered an inlet manifold into which air enters from duct 72, which encircles the housing 140, and is jetted directly outward through the nozzles against the sheet.

lFrom the sheet the air passes horizontally each way. from the center of the sheet to the narrow sides of the headers, through ports 155, and out through exhaust duct 74 leading back to fan 71. As shown in Fig. 8 a vertical passageway is formed at the narrow side of each header and this passage is enclosed at its narrow sides by the end of the header and the portion of wall 140 directly opposite, and at its broad side by two sheets of metal 153 placed at right angles to these surfaces. These sheets contain screened ports 155 which are located about two feetapart vertically and adjustable so as to vary the air, distribution at various levels. The cross-sectional area of these vertical passageways is of course designed to handle the air apportioned to them at the necessaryl velocity. l

, Ducts 80, 80' are vented to the outside atmosphereat, the rate necessary to exhaust the air which leaks in at such points as doors 81, 82. This exhausting of airis,

. 75, necessary in order to guarantee that air is drawnlinward through the 4apertures especially Aat-the top of the tower `Ii'here the stack `eiiect is greatest. kIn practice no more airis vexhausted than is necessary to maintain suction through rapertures 60. .Thebulk of the air is recirculated, reheated, and rehumidified. :Each and every aperture 60 has adjustable flaps that are positioned so that the open ing can be made as small as is practical. This is determined by the amount of sheet flutterexperienced.

vMidway of each of the 5 passes in the humidifier are 5 pairsof power-driven rolls (not shown) which steady the sheet in a manner similar to rolls 123, 124 between zones I andll (Fig. 6). Each pass of the humidifier has a-seal chamberat the top and bottom with finned heating coils similar to-units 125, 126 (Fig. 6) to heat up the air that bleeds in through-the apertures where the sheet enters and leaves each pass. There are screens similar to screen 11() (Fig. 2) across these steam pipes to catch bits of sheet. `Midway of the humidifier there are also seal chambers in each pass -above and below the 5 pairs of rolls mentioned. These seal chambers help to draw olf the air that comes through the access doors S1, 82 when they are open.

IFigures 8 and 9 bring out a feature of construction in the humidier which is lbelieved unique in this connection. Moisture which condenses in the housing 140 would normally leak, to some extent, around the edges of welds 141 in inner lining 140a, and then run down along the interior through insulation `140C. The orthodox solution to this problem is to drill holes at various points in fthe outer wall to let the condensation drain out. This is undesirable because it not only weakens the structure but leads to'rusting of the surface. This problem is solved as shown in Figs. 8 and 9 by putting up the outer shell in sections leaving a gap between them, and laying aneN-shaped gutter 160 in this `gap to collect the seepage draining down through the'sections of Wall immediately above. At one corner of the structure is a pipe1162 which carries the run-olf from all four walls down for disposal.

The machine is threaded by a threading cable which is afcontinuous loop. The cableenters at the coating head 13, 'goes vertically up the dryers 20, 35, around the pull roll 51, andthen follows the general path of the sheet as it r` festoons up .and down in the humidifier. It then laces around the several rolls which lead to the wind-up, around various pulleys to slack take-up means (not shown) and across'the aisle to coating head 13 again. Normally this threading cable is stationary.

(During threading, the operator manually laces the paper from the mill roll 2 around the dancer roll 6 and tension rolls 7, through the prehumidiiier 8, around spreader roll 10, and over and under the rolls in the coating head 1'3, with dip tank 14 having been lowered on its piston and the squeeze rolls 16, 16a opened. The sheet is manually threaded between the squeeze rolls 16, 16a and Ydoctor rolls 17, and pulled by hand until the Wrinkles and folds are out of it. The operator then clamps an attachment to the cable and by one or more means ties the twisted end of the sheet to the attachment. The sheet is now ready to b e pulled through the machine by the'threading cable.

The operator brings the dip tank 14 up into position, closes the doors, cranks the squeeze rolls 16, 16a to their proper setting, and actuates electrical clutches at the top'pull rolls and the last pull rolls so that the cable is tied into a driving means at these rolls simultaneously. The pull rolls are all started at once, the cable being driven likewise, and the sheet is pulled through themachine at a slow rate. When the cable attachment gets the sheet around through the wind-up the operator breaks the sheet and wraps it around the wind-up core. The electrical clutches are then disengaged and the cable is disconnected from its tive driving points simultaneously.

-An important feature of vthis design is ythat one man can thread lthe machine, while on conventional Yequipment of thisftype, three .menare required.

An important innovation in the design of this application .is that the sheet unwind stations and wind-up are located on opposite sides of a common aisle. This en ables one `operator to handle the machine under normal conditions and observe its operation both at the unwind and wind-up stations.

The system herein described is designed for a maximum sheet speed of 600 feet/minute and a minimum of ISOeet/minute.

For convenience the invention has been described .with particular reference to regenerated cellulose sheets and films (which in the dry state are water-sensitive), since it is here that the Iinvention displays its greatest advantages. However it is to be understood that the invention is also applicable in general to sheets and films which in the dry state are water-sensitive, including those cast from substituted cellulose ethers such as glycol cellulose, methyl cellulose and ethyl cellulose, substituted cellulose esters such as acetylated cellulose and substituted cellulose ether-esters, such as acetylated, substituted ethyl cellulose, also sheets and ltns castfrom albuminous materials such as gelatin, and from other water-sensitive film-forming materials, such as alginic materials.

I claim:

l. Apparatus for drying a continuous sheet of material containing volatile solvent comprising a vertical tower having upstanding opposite inner walls forming a chamber, means for drawing the sheet up through said charnber between said walls, a plurality of horizontal elongated nozzles mounted on said walls at substantially uniformly spaced intervals and directly opposite each other, a pair of vertical elongated headers of substantially rectangular cross-section for supplying air to said nozzles, each of said opposite inner walls forming one wallof said headers, a pair of exhaust manifolds positioned directly behind the headers, said exhaust manifold and headers being ycoexteusive and similar in form, said tower having outer walls forming a housing enclosing said headers and manifolds, said housing Vforming the back wall of the exhaust manifolds and being spaced from the end walls of the headers and manifolds sufriciently to form a vertical channel along said end walls, said channels extending the full height of the drying chamber and permitting the solvent-laden air withdrawn from the sheet to pass outwardly from the sheet in both directions, a series of ports spaced vertically along the end walls of the exhaust manifolds and communicating with said channels so as to permit withdrawal of the solvent-laden air from said channels and into said manifolds, and means for individually adjusting the dimensions Vof the ports so that the rate of exhaust can be varied at various levels of the dryer.

2. Apparatus of claim l wherein a screen extends outwardly from the edges of each of said inner walls and across the adjacent vertical channel to the housing wall, said screens extending the full height of the chamber and serving as a filter to prevent large solid particles of sheet from entering the exhaust manifolds.

3. Apparatus for drying a continuous sheet of material containing Volatile solvent comprising a vertical tower having upstanding opposite inner walls forming av chamber, means for drawing the sheet up through `said chamber between said walls, a plurality of horizontal elongated nozzles mounted on said walls at substantially uniformly spaced intervals and directly opposite each other, a pair of vertical elongated headers of substantially rectangular cross-section for supplying air to said nozzles, each of said opposite inner Walls forming one wall of said headers, an inlet duct connected to theinlet headers, means for forcing a drying gas through said duct and into the headers, -a pair of exhaust manifolds positioned directly behind the headers, said manifolds andheaders being coextensive and similarin form, said tower having outer walls forming a housing :enclosing 9:. said headers and manifolds, said housing forming the back wall of the exhaustA manifolds and being spaced from the end walls of the headers and manifolds suiiciently to provide a vertical channel along said end walls, said channels extending the full height of the drying chamber. and permitting the solvent-laden air withdrawn from the sheet to pass outwardly from the sheet in both directions, a series of ports spaced vertically along the end walls of the exhaust manifolds and communicating with said channels so as to permit withdrawal of the solvent-laden air from said channels and into said manifolds,A said ports having means for individual adjustment of port dimensions so that the exhaust rate therethrough can be varied at various levels of the dryer, screens extending across said channel so as to prevent fragments of sheet from entering the exhaust ports, an exhaust duct connected to said exhaust manifolds and extending outwardly of the tower for exhausting the solvent-laden air from said manifolds, a second vertical tower similar in construction to and superimposed upon the first tower, said first-mentioned means serving to draw the sheet through the second tower, and a recycle line connecting the exhaust duct from the second tower with the inlet duct to the rst tower.

4. In an apparatus as defined in claim 3 further including solvent recovery means located outwardly of the vertical towers and connected to an exhaust duct from the rst tower and the recycle line from the second tower.

5. In an apparatus as dened in claim 4 further nclud-ing dampers in the recycle line for selectively connecting the recycle lines with the inlet duct from the first tower and said solvent recovery means.

6. A wall construction for a vertical housing comprising a continuous inner shell, a discontinuous outer shell, said outer shell being constructed in sections, each section separated by a gap from the section immediately above and below so as to form a series of parallel horizontal grooves extending all the way around the housing, a layer of insulation between said inner and outer shells, and means for draining the insulation of moisture which collects therein, said means comprising a gutter trough positioned within each groove and extending the full length thereof, and means for drawing olf moisture which accumulates in said gutters.

7. Apparatus for treating a running sheet material including walls forming a housing, a pair of supply chambers positioned within said housing, said supply chambers disposed in spaced apart relationship relative to each other and the walls of said housing, means for delivering a treating lluid to said supply chambers, means for drawing a sheet material along a path extending between said supply chambers, at least one nozzle mounted on each of said supply chambers for directing a treating fluid from said supply chambers and against opposite sides of a sheet material traveling therebetween, walls extending from each of said supply chambers to said housing, said last-mentioned walls serving to partition the space between said housing and supply chambers into at least one discharge chamber, and openings in said lastmentioned walls whereby treating uid directed against opposite sides of a sheet material traveling through said apparatus is withdrawn a-t opposite sides of said supply chambers and passes into said discharge chamber through the openings in said last-mentioned walls.

8. Apparatus for treating a running sheet material including walls forming a pair of spaced elongated headers, means for drawing a sheet material between said headers, means for supplying a treating lluid to said headers, a plurality of nozzles mounted on said headers in opposed relationship for directing a treating lluid from said headers and against opposite sides of a sheet material traveling therebetween, walls cooperating with each of said headers to form a pair of elongated exhaust manifolds, said manifolds being disposed outwardly of said headers,

walls spacedfrom the opposite side walls of each of said headers and cooperating with walls of said manifolds to provide channels at opposite sides of each of said headers, said channels extending along substantially the entire length of the apparatus and permitting withdrawal of treating liuid along opposite longitudinal edges of the sheet material being treated, and openings in the walls between said channels and manifolds to permit withdrawal of treating fluid into said manifolds.

9. Apparatus for treating a running sheet material including walls forming a housing, at least two spaced headers positioned within said housing, each of said headers extending substantially the entire length of said housing and having a pair of side walls disposed in spaced apart relationship relative to a pair of opposing side walls of said housing, means formoving a sheet material between said headers, means for delivering treating lluid to each of said headers through opposite side walls thereof, nozzles carried by each of said headers for directing treating fluid from said headers and against opposite surfaces of a sheet material traveling therebetween, walls extending between each of said headers and said housing to provide exhaust manifolds at the opposite sides of each said headers, openings in said last-mentioned walls allowing treating lluid to ow from the area between headers and into said exhaust manifolds, and an exhaust duct connected to said manifolds for removing treating uid therefrom. y

10. Apparatus for treating a running sheet material including walls forming a housing, a pair of supply charnbers positioned within said housing, said supply chambers disposed in spaced-apart relationship relative to each other and the walls of said housing, means for delivering a treating fluid to said supply chambers, means for drawing a sheet material between said supply chambers, at least one nozzle mounted on each supply chamber for directing a treating fluid from said supply chambers and against opposite sides of a sheet material traveling therebetween, walls extending from said supply chambers to said housing to provide at least one discharge chamber, openings in said last-mentioned walls whereby treating fluid directed against opposite sides of a sheet material traveling through said apparatus is withdrawn at opposite sides of said supply chambers and passes into said discharge chamber through the openings in said last-mentioned walls, a second sheet material treating apparatus of similar construction connected to the irst sheet material treating apparatus, means for withdrawing treating uid from said second treating apparatus and conveying the same to said first treating apparatus, and means for regulating the ow of treating material through said last-mentioned means.

l1. Apparatus for treating a Continuous sheet material including walls forming a housing, a series of spaced headers positioned within said housing, each of said headers extending substantially the entire Ilength of said housing and having a pair of side walls disposed in spacedapart relationship relative to opposite side walls of said housing, rolls disposed adjacent to the opposite ends of said headers for advancing the sheet material along a sinuous path between said series of spaced headers, means for delivering a treating uid to each of said headers through opposite side walls thereof, nozzles carried by each of said headers for directly treating fluid from said headers and against opposite surfaces of a sheet material traveling therebetween, walls extending between each of said headers and the said housing to provide exhaust manifolds at the opposite sides of each of said headers, openings in said last-mentioned walls allowing treating uid to flow from the area between said headers and into said exhaust manifolds, and an exhaust duct connected to said manifolds for removing treating fluids therefrom.

12. Apparatus as delined in cla-im 1l wherein treating fluid is a humidifying atmosphere and wherein certain of said rolls are cooled to effect a chilling of a sheet material il?! during selected portions ofits .snuous travel through the apparatus.

13. Apparatus as defined in claim 11 wherein the Walls of said housing include a continuous inner shell, a discontinuous outer shell, said outer shell being formed in sections, each section separated by a kgap from the sections immediately above and below so as to form a series of parallel horizontal grooves extending all the way around the housing, a layer of insulation disposed between said inner and outer shells, and means fordraining the insulation of moisture which collects therein, said Vmeans including a trough positioned withineach of Asaid grooves and extending the full length thereof, and means for drawing off moisture whichaccumulates in said troughs.

Retereucested ,in thetlwfthsfpatent UNITED STATES 'PATENTS Seidell etal. Y 11113110.1928 Charch et.al. V..V Oct. 6, 1931 Willis 1 Mar. 13, 193.4 Coates V vMay 1, 19,34 Boyer. et al Aug. 18,1936 Spooner `Nov. 10, 1936 Gehnrich Y Ian.;2 1, 1941 Mayer Aug. .7, Y19.45 Dungler ....V `Apr. 1,1952

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