US1606824A - Drying cellulose films - Google Patents

Description

Nov 16 1926.

, 1,606,824 J. E. BRANDENBERGER DRYING CELLULO SE FILMS Filed Jan. 26, 1924 3 Sheets-Sheet 1 51m uc H To: Jafzzwiflmizdeizhryez" Quorum Nov. 16 1926. 1,606,824

J. E. BRANDENBERGER DRYING 7 VCELLULOS E FILMS Filed Jan. 26, 1924 3 Sheets-Sheet 2 Snow,

Nov. 16 1926.

1,606,824 J. E. BRANDENBERGER DRYING CELLULOSE FILMS Filed Jan. 26, 1924 3 Sheets-Sheet 5 anuewtoz Patented Nov. 1a, 1926.

UNITED STATES PATENT OFFICE.

JAQUES EDWIN BRANDENBERGER, OF NEUILLY-SUB-SEINE, FRANCE, ABSIGNOB TO LA socrfirfi: LA GELLOPHANE SIEGE S;OCIA.L, F LOUVRE, FRANCE.

DRYING CELLULQSE FILMS.

Application filed January 26, 1924, Serial No. 688,873, and in France February 12, 1923.

This invention relates to improvements in drying cellulose films in general, and more particularly cellulose films derived from aqueous solutions of cellulose such, for in- 5 stance, as an aqueous solution of sodium cellulose xanthate.

The possibility of continuously producing cellulose films is common knowledge,the said films being rolled up in rolls in pro- 1" portion as they are manufactured, the film on each roll being-as long as desired. Cellulose films are industrially utilizable if they are dried after being manufactured, but the drying of the films, however, involves great diificulties in practice. If merely exposed to the air, the cellulose film shrinks, shrivels up, loses most of its transparency and becomes of little value for industrial purposes. It has also proven unsatisfactory to anchor or hold in fixed position the edges of the film while it isdrying, as this results in cracks and breaks in the film either while drying or when it is removed.

Attempts have been made to obviate these disadvantages by means of machines which act to prevent the film from shrinking while it is drying; in these machines the film was held at all points by means of elements which did not compress it to any marked ex- 39 tent butm'erely held both faces of the film in contact with'tl1'e rigid surfaces of the said elements. "lTo that end, the film was fed between a series of cylinders rollingover one another and arranged so that one or the other face of the film was constantly in contact with the surface of one of the cylinders. This method of proceeding did prevent the film from shrinking, but was not altogether satisfactory, for instance inasmuch as the surface of the film was scored owing to the pressure, even though slight, exerted by the cylinders thereon.

The present invention relates to a. method of drying which obviates these disadvantages, and it also involves an apparatus for carrying the said method into practice.

The improved method or process is based on the following observations: It has been found that if the cellulose film, while it is drying, is continuously passed over cylinders without either of the faces of the said film width, the extent of shrinking being dependent upon the length of film which at a. certaln time is not in contact with any cylinder, i. 'e., upon the distance apart of the cylinders. The process according to this invention consists, therefore, in drying the cellulose film by causing it to pass over a series of cylinders or rolls which exert no pressure upon the film but merely guide it, with the result that a film is produced which is perfectly smooth, remarkably transparent and which is uniformly shrunk relatively to its initial dimensions, the shrinkin bein accurately predetermined by suita ly a justing the clearance between the rolls.

Heretofore the film was altogether prevented from shrinking by the pressure to which it was subjected, which pressure, even when as slight as it could possibly be made, detrimentally' affected the final product. Aecordin to the present invention, the film is dried without the exertion of any pressure thereon, and it is allowed to shrink uniformly to an accurately predetermined extent.

The process maybe carried into practice by means of any suitable apparatus, but preferably by means of that subsequently described, which comprises a series of driving rolls adapted to rotate another series of rolls, the working faces of these rolls (i. e. the faces on which the film is carried) having no point of contact with each other so that the film is at no time under any pressure. To accomplish this, both ends of each roll, at points beyond the portion with which the fi lm comes in contact, are fitted with rings or flanges forming arolling track. the ends of the driven rolls resting on the driving rolls through the medium of these rings which serve the purpose of providing a clearance between the working faces of ad- 5 jacent rolls and which also afford the means for driving one set of rolls from the other set, as well as for preventing endwise displacement of the rolls.

An apparatus whereby the process according to this invention may be carried into practice is illustrated by way of example in the accompanying drawings, in which:

Figure l is an end elevation showing a number of the rolls of the apparatus.

Figure 2 is a diagrammatic cross-section through the centres of the said rolls and also through the winding mechanism.

Figure 3 is a partial detail view of two rolls, looking from line 3-3 of Fig. 1.

Figures 4 and 5 illustrate a method of rotating the drivin rolls and means for circulating heated uid such, for example, as air in some of the rolls.

Figures 6 and 7 show details of the winding mechanism.

The apparatus represented comprises a set of rolls 1 rotated by any desired means in the direction of the arrows. Each end of each of the rolls has a ring or flange 2 forming a rolling track. Each of the driven rolls 3 is likewise fitted at each of its ends with a ring or flange 4. The rolls 1 are set at a suitable distance apart, and the rolls 3 rest with their rings or flanges 4 on the rings or flanges 2 of the rolls 1, as shown in Figures 1 and 3. The rolls 3 are supported on, and driven by, the rolls 1 and rotate in the direction of the arrows. A clearance is provided between the working faces of all these rolls, the amount of clearance depending upon the thickness of the flanges 2 and 4. There is no point of contact between the working face of one roll and that of another roll.

The cellulose film 5 to be dried is engaged between the various rolls and is carried and fed by the same, as shown in Figures 1 and 2. The film is not compressed between the rolls owing to the gap or clearance between the latter, and at any one time a portion of the film is in contact with the face of the rolls 1, another portion is in contact with the face of the rolls 3 and a further portion is not in contact with either set of rolls. The last-mentioned portion is the one that shrinks when drying and which causes a final uniform shrinking of the film subjected-to drying if care is taken to move the film along at uniform speed and to render the drying uniform. The system of rolls, the component members of which may be arranged in one or more tiers or superposed rows, is preferably located in a closed chamber forming a kind of drying room or enclosure, the temperature of which may be raised (either by direct heating or by circulating a fluid) to the desired extent for the purpose of properly drying the cellulose film to be treated.

The drying apparatus may be used separately for drying a cellulose film previously wound up in a roll, or it may be used in combination with the machines for manufacturing and manipulating the said film, i. e., in cases where the film is not fed to the drying apparatus from a storage drum or roll, but straightaway from the said machines In any case, however, the film coming from the apparatus herein described will be found to be dried and uniformly shrunk and may be wound up on a suitably rotated receiving drum. I

One of the essential features of the invention consists in driving the rolls 1 by resilient or elastic means of any suitable kind,

for instance a slip drive, as opposed to a above described, but also longitudinally. If,-

now, the driving rolls were rotated by rigid or positive driving means, the film would be subjected to tension and would break owing to the fact that the longitudinal shrinking is not the same at the various points of the apparatus.

for the shrinliing of the film, and the rotating of these rolls to be determined in whole or in part by the linear motion of the film, which makes necessary a slipping, resilient, or elastic drive. The latter may be of an desired type'; for instance, a belt drive wit 1 belts adapted to slip on the pulleys.

Figs. 4 and 5 illustrate by way of example a belt-and-pulley drive. Each of the rolls 1 is carried on a shaft 6 supported in suitable bearings fitted to the-walls of the drying chamber, and a pulley 7 is keyed to one end of each shaft externally to the said chamber. A main shaftv 8, driven in any desired manner, is adapted to drive through suitable gearing 19, or in some other preferred way,aseries of shafts 9 all parallel to the shafts 6 and equal in number to half the number of rolls 1. Each shaft 9 rotates two rolls, and is provided to that end with two rigidly secured pulleys 10 and 11. The pul- It is thus necessary to allow the speed of the driving rolls to compensate ley 10 drives, through a belt-12, the pulley 7 of one of the rolls 1, and the pulley 11, through the medium of a belt 13, drives the pulley 7 of the following roll, (Figs. 4 and 5). The tension of the various driving belts 12, 13, etc. is so adjusted that the belts are adapted to slip on their pulleys for the purpose of producing the required give or elasticity.

On leaving the last drying roll, the film passes to a mechanism which winds it up and which also serves to maintain it under tension during its passage through the drythereafter wound up on another mandrel.

The mechanism per se forms no part of the actual invention and any mechanism suitable for the purpose may, therefore, be employed. The one illustrated is that which is regarded as preferable and, as shown, it

ill!

comprises a set of friction ears 22 in driving engagement with other riction gears 23, of which there is one for each of the mandrels 20. The gears 22 are loosely mounted on stub shafts 24 secured to one of the standards 21; and one of these gears, in this instance the upper one, has rigidly connected to it a pulley 25 driven by a belt 26 from a larger pulley 27 which is fixed to a horizontal shaft 28 also journaled at one end in the standard, shaft 28 being connected by a suitable intermeshing gears 29 to the main shaft 8 to be driven therefrom.

The mandrel spindles are disposed in horizontal co-planar relation with horizon tal stub shafts 30 on which the gears 23 are loosely mounted and which are alsofastened to the standard; the gears 23 having associated with themv similar gears 31 in mesh with.and driving gears 32 on the mandrel spindles. The cooperating gears 28 and 31 are related by devices which function as slip clutches to variably couple them together, and means are provided for regulating the action of these clutches! In the constructionillustrated, leather disks 33 are employed, and a presser plate 34 is splined on the stub-shaft 30 in' position to bear against the outer face of gear 23 and is subjected to the action of acoil spring 35 which encircles said shaft and the tension of which is adjusted by a hand wheel 36 or the like.

It will be apparent, therefore, that by properly adjusting the corresponding hand wheel, the degree of frictional coupling between any pair of gears 23 and 31 can be regulated at will from a maximum in which the two gears rotate at the same speed with no slippage whatever, to a minimum in which gear 23'virtually rotates idly and transmits no motion to its associated gear 31. The latter gear, assuming that it is in mesh with the gear 32 on the mandrel which is being filled, determines the speed of rotation of the mandrel and, hence, the tension exerted on the film during the winding operation, thus permitting the tension to be regulated in accordance with the increasing diameter of the roll of film on the mandrel.

The rolls 1,moreover, may be utilized to assist in, or to supplement, the drying action above described. Hollow rolls may be resorted to for this purpose, and may be heated either directly or by circulating a heated fluid therein, or in any other convenient manner. Heated fluid may be supplied to the various rolls 1 through headers 14 and suitable piping 15 (Fig. ,5). The temperature to which the rolls are heated must be regulated so as not to produce, at any point of the drying apparatus, a layer or film of steam between the cellulose film and the heating face of the roll, as this would have the serious drawback of doing away with contact and, therefore, adherence between the said cellulose film and of the roll, the conse and unforeseen shrin The outer casing or drying chamber surrounding the ro s may be dispensed with in an apparatus fitted with internally heated rolls as described; but the casin is nevertheless advantageous inv that it afl brds the possibility of accelerating the drying operation by enabling the circulation of heated air therethrough.

The film shrinks transversely in accordance with the thickness of the flanges 2 and 4, so that it is possible to construct a'machine which, for a given thickness of flange or ring and under definite conditions of drying, yields a filmshrunk to a predetermined extent. Rolls may be used the flanges or rings of which are removable and, therefore, adapted to be replaced by rings of another thickness in order to shrink the material to various degrees in the course of the drying operation.

It is understood that the above-described structural details are merely given by way of example and do not limit the scope of the invention.

I claim as my invention:

1. Apparatus for drying continuous celluthe heating face ing of the material.

lose films, comprising two separate sets of coact-ing rolls around which the film is fed, means for driving one set, and mutuallyengaging rings on the opposite ends of contiguous rolls of the two sets for driving the other set from the first set while maintaining the working surfaces of the contiguous rolls of both sets out of contact with each other, thereby to support and'guide the film without subjecting it to compression; substantially as described.

2. Apparatus for drying continuous cellulose films, comprising two separate sets of coacting rolls around which the film is fed, mechanism includin slip-driving devices for rotating the rolls of one set, and means for driving the rolls of the other set from the first set; substantially as described.

3. Apparatus for drying continuous cellulose films, comprising two separate sets of coacting rolls around which the film is fed, mechanism including slip-driving devices for rotating the rolls of one set,and means for driving the rolls of the other set from the first set while maintaining the working surfaces of contiguous rolls of the two sets out of mutual contact, thereby to support and guide the film without subjecting it to compression; substantially as described.

4. Apparatus for drying continuous cellulose films, comprising a set of driving rolls, a set of rolls coacting with the driving rolls and driven therefrom, the two sets of rolls conjointly feeding the film between them, a main drive shaft, a series of driven shafts connected therewith, and slip-drive connecuence being an undue tions between each driven shaft and} two of- (i'AbParatus. for drying continuoustcel 15 the driving rolls. 5. Apparatus lulose films, comprising a set of drivingrol ls;

a set of driven rolls, mutually-engaging rings on the opposite ends of contiguous driving and driven rolls to operate the latter from the former and to maintain their working surfaces in spaced relatiornthe two sets of rolls conjointly feeding the film between them, a main drive shaft, a series of driven: shafts connected therewith, and slip-drive connections between each driven shaft and two of the driving rolls.

' i for drying continuous cel;

lnlose films, comprising a set of driving rolls, a set of rolls coacting with the driving rolls and driven therefrom, the two sets of rolls conjointlyfeeding the film between them, a main drive shaft 'a series of driven shafts connected therewith, slip-drive connections between each driven shaft and two of the driving rolls, and mechanism for Winding up the film and exerting a variable tension thereon.

In-testimony whereof I afiix my signature.

.JAQUES tnwm BRANDEhBERcER.

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