US3100306A - Liquid application to running lengths of fibers in superimposed baths - Google Patents

Description

Aug. 13, 1963 c. F. OLDERSHAW 3,100,306

LIQUID APPLICATION TO RUNNING LENGTHS OF FIBERS IN SUPERIMPOSED BATHS Filed May 28, 1958 2 Sheets-Sheet 1 INVENTOR. C/mrks F. O/oens/zaw WNEY Aug. 13, 1963 c. F. OLDERSHAW 3,100,306

LIQUID APPLICATION TO RUNNING LENGTHS 0F FIBERS IN SUPERIMPOSED BATHS 2 Sheets-Sheet 2 Filed May 28, 1958 BY MW K HTTOANEV United States Patent 3,1tltl,3tl LIQUID APPLICATIQN T0 RUNNING LENGTHS 0F FBERS m SUPEQSED BATES Charles F. Gldershaw, Concord, Calif., assignor to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Filed May 28, 1958, Ser. No. 738,547 6 Claims. (ill. 8-15L2) This invention relates to a new and improved method of handling continuous or essentially endless sheets or webs of flexible material, especially filamentary textile material, particularly when it is assembled in tow bundle form, through consecutive and sequential liquid treating baths.

In many textile processes, especially those in which the various man-made synthetic textile fibers are being manufaotured, it is oftentimes found necessary or advantageous to subject the textile material in filamentary form to various treatments that may be accomplished in a plurality of sequential liquid treating baths. Thus, filamentary or strandular textile material may be subjected to washing for purposes of extracting undesired impurities therefrom, or to the action of beneficial treating agents (including finishes, lubricants, dyes, textile assistants and so forth). Quite frequently, especially in connection with synthetic textile fibers, it is desirable or necessary to hot stretch or physically elongate the textile material in order to effect its orientation. This may advantageously be accomplished While the textile material is immersed in a hot liquid bath, such as a hot aqueous bath (which may also simultaneously provide washing or other treating effects).

In many such operations, it is generally expedient to handle the fibers while they are in continuous filament form and arranged in a bundle or tow of assembled filaments. Such a tow bundle may consist of a rope-like mass of the filaments, such as in sliver or roving-resembling arrangements or, frequently with greater advantage, as relatively thin and fiat, rectangularly cross-sectioned assemblies that have a tape or ribbon-like configuration. It is not uncommon for such tow bundles in the manufacture, for example, of say, 1 to 10 denier per filament products to be comprised of from 10,000 or 50,000 to 200,000 .or more individual, component endless or continuous filaments. Thus, the resulting assembly is one of considerable magnitude.

Synthetic fibers that have been prepared by wet spinning techniques are oftentimes handled through various liquid treatments, including hot stretch baths for orientation, in the form of such large size tow bundles. Along with numerous other fiber-forming materials, many acrylonitrile polymer compositions, including polyacryloni trile, are beneficially suited for handling and processing in such manner. When polyacrylonitrile and certain other fiber-forming acrylonitrile polymers that contain in the polymer molecule at least about 80 weight percent of acrylonitrile are wet spun, it is quite advantageous to utilize aqueous, polyacrylonitrile-dissolving saline solutions of zinc chloride and its saline equivalents for such purpose in the preparation of the spinning solution that.

is employed, and nonpolymer-dissolving aqueous saline solutions of the same salt or salts for the coagulating spin bath, and to subsequently process the extruded aquagel filaments through various aqueous washing treatments and hot stretching baths prior to their being irreversibly dried to obtain the final desired, characteristically hydrophobic, synthetic textile fiber. As is well known, the hydrated aquagel forms of acrylonitrile polymers generally contain an amount of water in the aquagel which is at least gravimetrically equal to the'hydrated polymer.

It may oftentimes be preferable for the water to polymer weight ratio in an aquagel to be in the neighborhood of from about 1.521 to 20:1, respectively, although aquagel structures in which the water to polymer ratio is as high at 5 :1 or more may oftentimes be satisfaotorilyhandled.

In many processing arrangements wherein a synthetic textile fiber is being liquid treated during its manufacture, the treatment, as has been indicated-in the foregoing, is accomplished in a sequential series of liquid baths from and between which the filamentary material is physically handled and transferred. This is generally performed by means of rollers or roller systems or other strand advancing devices. Ordinarily, the filamentary material is withdrawn from a first liquid bath by one or a plurality of rolls and passed in air through another roller installation which serves to immerse the filamentary material in the next sequential bath, and so forth, until the final liquid treatment has been accomplished. While in certain liquid treating operations,,such manner and apparatus for handling filamentary material is suitable, it frequently involves certain difficulties which might well be eliminated.

Thus, the plurality of rollers and similar installations for separately withdrawing and sequentially immersing the filamentary material out of and into the treating baths tend to preclude arrival at compact physical arrangenrents in the apparatus installation. This is particularly the case when it is desired to utilize a plurality of several liquid treating baths in superimposed relative disposition. In other cases, in addition to the lack of compactness, the requirement to use pluralities of separate withdrawing and immersing rollers or the like installations whereby the filamentary material being treated is passed out of liquid contact and transferred between baths through the air introduces significant disadvantage. Occurrences :of this nature are not uncommon when the filamentary material is being processed through a plural sequence of hot stretch baths, wherein it is stretch drawn and oriented by physical elongation while being immersed in hot stretching liquids. Oftentirnes, during the transfer through air from stage to stage, the filamentary material being hot stretched is caused to become partially cool by heat transfer with convective currents of air surrounding the operation. Of course, this may result in a temperature differential being obtained from one part of the filamentary material to another, particularly when tow bundles of considerable magnitude are involved in the operation.

Such non-uniform cooling tends to cause difiiculties in a stretching operation. For example, when a tow bundle that has been withdrawn from a first hot stretch bath is passed through air and partially and unevenly cooled prior to being resubmerged for resumption of stretching in the next subsequent hot liquid stage, the diile'rentparts of the tow bundle tend to begin stretching at diiferent'time intervals during the resubmergence' in the second stage. This is for the reason that the stretch apparently begins in any given crystalline, thermoplastic synthetic textile mafilaments in the tow. The reason for this is thought to be i that, although most of the individual component filaments in a tow bundle are presumed to be (and attempted to be arranged) parallel to one another, certain of the compo-j nent endless filaments therein tend unavoidably to be disposed in the tow bundle in a not strictly parallel fashion with the length of the tow so as to lie at greater or freel'y'nor, a the atmosphere;

lesser degrees of divergence from the main parallel mass. oftentimes, the non-parallel filaments are caused to be broken by the action of one part of the substantially parallel mass beginning to stretch while a'neighboringpart fails todoso. l 7

Furthermore, cooling of a heated tow bundle exposed to air by convective air'currents is such an uncontrolled and variable process that theamount of such cooling can readily change in a nandom fashion as a function of time; This also changes the location at which the average stretch begins in any given hot stretch stage so as to alter the fiber inventory in the particular stage under question. As a consequence, the true amount of fiber stretch or physical elongation obtained during the time of change may be seriously and disadvantageously altered. As a consequence, many deleterious effects may be occasioned upon fiber quality tending to-cause less than premium gradeproducts to be obtained a c As will be appreciated by those who are skilled in the art, analogous and related problems and difliculties are involved in the handling and processing through various operations of other materials obtained in the form of flexible sheets or web s, such as plastic sheet'and film,

textile yardage, felt, paper, and the like which is processed continuously through various liquid treatments as substantially -(or completely) endless or continuous lengths.

It would be anadvantage to provide a new and improved method for treating filamentary and the like indicated materials in liquid baths so as to avoid the abovementioned difficulties and limitations, particularly during hot stretch operations in sequential bath stages of synthetic textile fiber materials. Amongst the several cognate purposes, objects and design of the present invention there maybe made particular mention of and included: I j

To enrich and make significant contribution to the art 'of process handling of various textilematerials; To'provide' an efiective and efficient liquid treatin method for textilefibers that may be either of the artificial or synthetic varieties or of natural origin;

To do' so especially for fibers multiple, continuous filament tow bundles or in analogous sliver or' roving-' like arrays; V r l 7 To do so particularly for multiple continuous filament artificial and synthetic textile fiber tow bundles and the the liquid'treatment of textile fibers'through sequential treating'stages that are advantageously superimposed one above the other;

To provide'a method for liquid treatment of textile'. fibers-through sequential treating stages wherein the matelr-ial being transferred; from stage to stage is neither ;To provide a method that is particularly adapted to hot stretch synthetic, textile fibers in tow bundle assemblages through a plural se'quence'of hot stretching liquid baths;w To provide a method particularly adapted for thecompact and eflicient handling of tow bundles of acrylonitrile ment of continuous lengths of other flexible sheet-like or web materials that are processedfin physical forms and embodiments approximately to fiber tow bundles, including-diverse materials of the types mentioned in the foregoing.

' :The indicated objectives and their associated advantages completely exposed manner subjected to 1 4 r and benefits may be achieved readily by practice of th present invention. Accordingly, in its most elementary aspects, the present invention comprehends a method using appropriate apparatus, for the liquid treatrnent of textile fibers, of either synthetic or natural origin, especially those arranged in a tow bundle or equivalent array and other flexible sheet-like materials of similar form, through a sequential series of superimposed baths of treating liquid (to, in arrangement wherein each bath is contained in troughs or relatively fiat and shallow pans positioned directly one on top of the other) in which the transfer means between each of the sequentially related stages is comprised of a single large roller, the. bottom portion of which is immersed in the liquid in the lower stage for purposes of admitting or withdrawing the textile fiber or the like thereto or therefrom; the upper peripheral portion of which is positioned with an uppermost tangent line thereto being about parallel to or slightly higher than the liquid level in an upper stage in which said roller is not physically immersed and from or at which said roller operates to withdraw or admit the fiber or the like material being treated. V

The invention is further delineated and manifest, in both method embodiments: that are not intended to be limiting thereof, in the iollowingdescription and specifi- I cation, taken in connection withthe accompanying drawing wherein:

FIGURE 1 is a simplified schematic, representation presented in fragmentary perspective view of the single roller tow bundle or other filament or material'handling means between sequential stages of the present invention; FIGURE 2 is a schematic elevation presented in broken out cross-section of a plural stage liquid treating bath according to the invention in operation with a tow bundle passing therethrough;

FIGURE 3'is a fragmentary perspective View, partly in section, illustrating the handling of filamentary or'other material in accordance with the present invention; and FIGURE 4 is a simplified schematic representation of a typical conventional arrangement for handling filamentary material through sequential liquid treating stages.

In the ensuing description, the present invention is predominantly illustrated in connection with fiber tow bundles.

However, as indicated in the foregoing, it is readily apparent that other flexible sheet-like materials in continuous lengths are also capable of being utilized and handled in the practice of the method of the present invention using an appropriate apparatus for the purpose.

- With initial reference to FIGURE 1 of the drawing, there is shown a superimposed'pair of pans or troughs P1 and P2 for containing sequential baths of beneficial treating liquid fora tow bundle or other array of fibers or sheets or webs of other materials (not shown in the figme) to be passed in sequence through the baths contained in the superimposed troughs.- The troughs P1 and P2,

which may be of'any desired or necessary length, width and depth, are positioned in vertical relative disposition. Asinigle large roller R is arranged at the end of the upper trough P1 in such a manner that its upper pe-' ripheral portion is at about the same height as (or .slightly'higher than) the intended liquid level in the bottom portion of the roller is arranged to extendinto the a trough P1. "The roller is positioned as closely as possible to the 'end Wall E of thetrough P1. Advantageously,

as indicated, the end wallE is sloped or slanted to accommodate the nearest possible approximation therea-ginst of' the roller R although vertical end walls can also be utilized for the side of the trough adjacent to the roller. The

lower trough P2 in such a'manner that it is at least partially immersed in any liquid that is contained therein. This, of course, advantageously causes the filamentary materialbeing handled over the roller to be drawn in immersion through the bath of treating liquid in the lower trough.

a The roller maybe mechanically rotated by any. suitable drive means (not shown) at any desired or suitable rate for accommodation of the liquid or fiber treatment being effected.

In FIGURE 2 there is shown an installation containing a plurality of superimposed bath containing troughs or pans P10, P11, P12, P13, P14- and P15, respectively, conttaining the respective liquid treating baths L1, L2, L3, L4, L5, and L6. Although they are shown to be open, covered troughs can also be employed. A tow bundle T of filamentary material is being sequentially passed rthrough the superimposed wash liquids in a generally upward manner, being introduced in the lowermost trough P14- about the admitting roller W2 immersed in the liquid L6 and, after having been withdrawn through the sequential stages, being forwarded away from the entire installation after withdrawal from the. uppermost trough Plil over the roller W1. The filamentary material is handled through and between the sequential stages around and about the rollers R7, R6, R5, R4, R3, and R2, respectively, and is withdrawn from the liquid L1 in the uppermost final treating stage about the immersing roller R1.

Each of the interstage transfer rollers R7 through R2, inclusive, are adapted to pass the tow bundle T directly from immersion in a lower stage to the next consecutive upper stage without permitting the filamentary material to experience substantial unprotected exposure to the atmosphere. This is accomplished, :as is evident, by employing rollers of such a diameter that their uppermost peripheral portion is about equal in height to the liquid level in an upper treating stage or trough while its lower most portion is immersed in a lower trough from which the filamentary material is being withdrawn for transfer to the upper trough. As a practical matter, there are no critical limitations in the design or size of the rollers or the bath-containing troughs between which the rollers transfer the filamentary material being treated. The trough can be of any desired size or shape to accommodate a suitable volume of treating liquid, taking into account the desired residence time at any given rate of travel of the filamentary material being passed through the bath. Likewise, the rollers can be of any desirable suitable size and diameter to adequately handle the filamentary material being treated With the obvious requirement that their diameters must be suificiently large to permit immersion in the lower stage and effective transfer of the filamentary material into an upper stage. Of course, the relative depth to which it is desired to immerse the filamentary material in any given treating stage will effectively govern the degree of immersion of the lowermost portion of any roller in the treating liquid.

While the filamentary material is depicted as progressing through the sequential stages in a generally upward manner in FlGURE 2 of the drawing (i.e., being admitted to the lowermost stage and progressing through the vertically superimposing stage until final withdrawal from the uppermost stage), it is obvious that the processing sequence can be reversed and the filamentary material introduced and initially admitted into the uppermost stage so as to progress generally downwardly through the stages for ultimate withdrawal from the lowermost stage in the sequence. The rate of rotation of the rollers, as will be apparent to those skilled in the art, depends almost entirely on the particular treatment being effected. Thus in ordinary washing or other liquid treating operations wherein the physical properties of the fibers are not being mechanically altered, it is generally desirable for all of the rollers to be operated at the same peripheral rate of speed. In stretching operations, however, the sequential rollers (or at least part of them) are operated at increasing peripheral rates of speed so as to eifect the desired physical elongation of the textile material being oriented.

There is no requirement, incidentally, for all of the rollers in any particular installation to have the same diameter, even though it may be most expedient for such arrangements to be in effect. If desired, however, the size and shape of the several troughs in a particular plural stage sequence may be altered to suit particular requirements, as may be the size and shape of the particular filament transferring rollers that are handling the textile material through and between stages. All that is necessary in any given roller is for it to be of an adequate diameter for the interstage transfer; to be immersible in a lower bath; and about of equal height in its. upper peripheral portion to the liquid level of the next immediate upper bath.

The rollers may be smooth surfaced or roughened, as may be desired and suitable in particular instances, and may be made out of any material of construction best adapted or deemed best qualified for the operation at hand. Likewise, the troughs may be of any suitable material of construction and may be built so as to permit internal fiow and/or agitation of the liquid contained therein. The troughs may also be adapted to sequentially pass the liquid from stage to stage in any desired countercurrent, concurrent, or mixed oountercurrent/concurrent arrangement relative to the filamentary material being handled through the stages. Thus, the liquid may be pumped upwardly through the troughs or it may be permitted to flow downwardly from pan to pan by taking advantage of gravity and overflow arrangements with each upper pan spilling excess liquid over into the pan immediately below.

A-dvantageously, as shown in FIGURE 3, the edge of the trough adjacent to the upper periphery of any of the filament transfer rollers may be provided with a bridging lip or scraper blade extension S from the uppermost edge of the trough extending to about the uppermost peripheral surface of the roller in order to provide smooth guided passage for and to control wrap ups of the filamentary material being handled into or out of the upper bath by means of the roller R.

As is apparent, the method of the present invention provides for exceptional compactness in a given installation. The compactness is secured to such an extent that, frequently, a reduction in the height necessary for any given number of required stages which is as great as 50 to 75 percent may be experienced in comparison to that needed when conventional varieties of sequential stages (such as those illustrated in FIGURE 4) are replaced with arrangements according to the present invention. Furthermore, particularly when hot stretching operations are being performed, the single transfer roll arrangement of the present invention accomplishes stage-to-stage trans:

fer Without substantial unsupported or unprotected exposure of the filamentary material to the atmosphere. This nicely avoids partial cooling of the filamentary material with convective cur-rents of air. Such an arrangement is of great significance when tow bundles of considerable magnitude are being handled through the sequential stages. As a consequence, a much more uniform and better controlled process may be eifeoted and minimized damage to or breaking of the individual components of a multiple filament arrangement may be achieved.

By practice of the present invention, all of the fibers being handled through the stages, particularly when hot liquid stages are involved, are substantially synthermally maintained by being kept in contact with either the transfer rolls (which are maintained at about the same tem perature as the treating liquid by virtue of their partial immersion therein) or due to actual submergence in the liquid. As a desirable consequence, the tem erature of the filamentary material being treated is continuously maintained at about the desired temperature of the treating liquid being employed. Stated alternatively, the beneficial design of the present invention does not permit the filamentary material to be moved to any significant extent through air wherein capricious convective air currents may be permitted to alter the temperature of the filaments. Furthermore, as is apparent from observation of the present design, apparatus used in practice of the method in accordance with the present invention is'much easier to thread or lace up, since it may be embodied with significantly fewer rollers for handling and transferring the tow or other filamentary material between any given number of stages. Likewise, having fewer rollers, the apparatus employed for purposes of the present invention permits a much simpler and more positive drive arrangement to be made. Also, with great advantage, the present arrangement avoids the use of idler rolls. The latter feature is of particular significance in stretching operations, wherein it is frequently experienced that the bearings on idler rolls tend to stick and cause disturbance in the control of the stretching operation.

In order to further illustrate the invention, an apparatus patterned after that shown in FIGURE 2 is employed for the hot stretching for purposes of orientation of a freshly wet spun, washed and partially (2.4 times) stretched tow bundlecf polyacrylonitrile aquagel filaments that consists of about 60,000 (sixty-thousand) individual continuous filaments, each of which has an ultimate denier, as a finely finished textile fiber product, of about three. Upon their introduction into the hot stretch stages, the aquagel filaments contain about 4 parts by weight of water to each part by weight of polymer (on a dry basis) therein.

A total of five superimposed wash baths are employed in the hot stretching sequence. Each of theb'aths, which is contained in a similar sized trough, has a total length of about feet and a Width of about 1 feet. The first of the baths is lowermost and is cold water. The last four are adapted to contain a hot stretch liquid (which is water at a temperature of about 99 C.) at an average depth of about 3 inches. Each of the troughs are spaced verticallyso that the bottommost part of each upper trough is about 8 inches above the liquid level in the next imrne diate lower trough. The tow is introduced into the lower- 7 most trough to be immersed in the cold Water therein under a first admitting roller having a diameter of about 12 inches and operated at a rate of rotation of about 15 rpm. which is so positioned thatits lowermost peripheral portion is just under the liquid level of the bath in the lowermost trough.

. The tow bundle is passedthrough the first hot stretch bath and withdrawn therefrom over a first transfer roll,

having a diameter of about l2 inches, which is operated at a rateof about 35 rpm. so as to impart a stretch of about 2.3 times to the filaments in the tow in the cold water of thefir'st stretch bath. The first transfer roll is immer'sedto a depth of about 2 inches in the liquid of the first cold water stretch stage. about the first transfer roller is passed on the surface of 'the roll directly into the next upper bath (which is the.

The tow withdrawn length (including the preliminary'cold stretching) is about 12 times its original extruded length. r

After final withdrawal from the last of the hot stretch stages, the aquagel fiber is irreversibly dried at about 150 C. for 15 minutes to transform it into the desired, char-. acteristically hydrophobic, textile fiber product. The filamentary material is produced in the indicated manner with excellent uniformity and control so as to obtain premium quality polyacrylonitrile synthetic textile fiber product. All of the finally manufactured fibers have substantially the same degree of orientation'and are produced without any significant breakage during the hot stretching operation.

, In contrast'with the foregoing, when the same stretcha ing openation was attempted with conventional apparatus using a plurality of sequential stages (each of about the same bat-h size) between which the tow bundle was transfenred through air over conventional multiple roller systems, as depicted in FIGURE 4- by mhe plumal roller system W10W11, W12 and W13-W14, operating to transfer the tow bundle T from the trough P21 to the trough P20, much more vertical space was required for the same operation. Dissatisfactory processing, nonuniforrnity, poor control, and inferior quality were also obtained in the conventionally pnacticed process. In addition, serious difiicul-ties were encountered with the conventional apparatus due to brealage of individual filament components of the tow bundle caused by the uneven cooling effects introduced in the open air passage of the tow bundle between the stages. 7 7

Excellent results s milar to the foregoing may be achieved when the present invenuion is practiced for conventional washing of filamentary textile material, or for other liquid treatments including lubrication or finishing, dyeing, bleaching, impregnation with various beneficial treating agents, such as polymeric dye assistin-g adjuvants, and the like on acrylonitrile polymer as well as other freshly Wet spun artificial and synthetic fibers as well as for the accomplishment of desired liquid treatments on tow bundles and the like arrays of various natural and other synthetic textile filaments and fibers using suitable baths of treating liquid for any intended purpose.

7 Excellent results may also be achieved when the method of Ithe present invention is used in an analogous manner for theliquid treatment of any other flexible sheet or Web like materials typified :by those mentioned in the foregoing which are handled through various processing operations in continuous or substantially endless lengths. Since many changes and alterations in practice of the present invention can be entered into readily without substantially departing from its intended spirit 'and scope, the invention is to be interpreted and construed not by strict l limitation to the foregoing illustrative specification and 7 ever limitations may be attributable to the prior art.

The second transfer roll withdraws incompletely stretched tow bundle from the second hot stretch bath and transfers it directly oflf its upper parallel portion to the next upper- 7 most bath, whereinthe filamentary material is immersed in the hot liquid and further stretched by withdrawal about rpm, respectively. Thus, the total stretch eifected ,7

. in the fivedescribed stages of the completely oriented aquagel fiber isabout 5 times so that its overall stretched What is claimed is:' V V 1. In a process wherein a continuous, flat, ribbon-like sheet of flexible material is treated with a beneficial treating liquid in a sequential series of at least two supermaterial between sequential superimposed stages out of and into the sequential liquid treating baths in said stages by means of and while said material is supported on a single, eircumferentialrotating surface which is in contact with the flat side of said material in said lower stage while being partially immersed therein and whose uppermost pemipheralpontion is about equal with the liquid level a next adjacent uppermost stage, said matenial being tnausferred from stage to stage without substantial unsupported 'freepassage through the 2. In a process wherein a textile fiber material in stmandular form is treated with a beneficial treating liquid in a sequential series of at least two superimposed liquid treating baths and said textile fiber material is sequentially passed out of and into the treating liquids in sequential treating baths, the improvement in the textile art for handling said stnandular material which comprises transtier-ring said stra-ndulat material bet-ween sequential superimposed stages out of and into the sequential liquid treating baths in said stages by means of and while said strandul-ar material is supponted 1011 a single, circumferential rotating surface which is in contact with said strandulatmaterial in said lower stage while being partially immersed therein and whose uppermost peripheral portion is about equal with the liquid level in a next adjacent uppermost stage, said strandular material being transferred from stage to stage without substantial unsupported free passage through the air.

3. The process of 2, wherein said textile fiber material is hand-led in the form of \a relatively flat, mibbonlike .tow bundle.

4. The process of claim 3, wherein said textile fiber material is an aory-lonitrile polymer in aquagel form.

5. The process of claim 4 and including the step of stretching said textile fiber material during its passage through said stages.

6. The process of claim 4, wherein more than two superimposed liquid treating baths are employed.

References Cited in the file of this patent UNITED STATES PATENTS 663,452 M aerrtens Dec. 11, 1900 2,501,480 Stec Mar. 21, 1950 2,693,689 .Hannay Nov. 9, 1954 2,720,442 Keggin Oct. 11, 1955 2,728,629 Blomberg Dec. 27, 1955 FOREIGN PATENTS 607,057 Germany June 4, 1931 362,557 Great Britain Dec. 10, 1931

Claims (1)

1. IN A PROCESS WHEREIN A CONTINUOUS, FLAT, RIBBON-LIKE SHEET OF FLEXIBLE MATERIAL IS TREATED WITH A BENEFICIAL TREATING LIQUID IN A SEQUENTIAL SERIES OF AT LEAST TWO SUPERIMPOSED LIQUID TREATING BATHS AND SAID MATERIAL IS SEQUENTIALLY PASSED OUT OF AND INTO THE TREATING LIQUIDS IN SEQUENTIAL TREATING BATHS, THE IMPROVEMENT IN THE ART FOR HANDLING SAID MATERIAL WHICH COMPRISES TRANSFERRING SAID MATERIAL BETWEEN SEQUENTIAL SUPERIMPOSED STAGES OUT OF AND INTO THE SEQUENTIAL LIQUID TREATING BATHS IN SAID STAGES BY MEANS OF AND WHILE SAID MATERIAL IS SUPPORTED ON A SINGLE, CIRCUMFERENTIAL ROTATING SURFACE WHICH IS IN CONTACT WITH THE FLAT SIDE OF SAID MATERIAL IN SAID LOWER STAGE WHILE BEING PARTIALLY IMMERSED THEREIN AND WHOSE UPPERMOST PERIPHERAL PORTION IS ABOUT EQUAL WITH THE LIQUID LEVEL IN A NEXT ADJACENT UPPERMOST STATE, SAID MATERIAL BEING TRANSFERRED FROM STAGE TO STAGE WITHOUT SUBSTANTIAL UNSUPPORTED FREE PASSAGE THROUGH THE AIR.

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