US3801401A

US3801401A - Apparatus for making convolute wound structures

Info

Publication number: US3801401A
Application number: US00183590A
Authority: US
Inventors: A Cope; S Cope
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1971-09-24
Filing date: 1971-09-24
Publication date: 1974-04-02
Anticipated expiration: 1991-04-02

Abstract

An improved apparatus for assembling a convolute wound structure suitable for use in making an element of a selective permeation separation device comprises 1. A WEB FEEDER ADAPTED TO UNROLL A WEB-LIKE FORAMINOUS MATERIAL IN SUBSTANTIALLY PLANAR FORM, 2. A TAKEUP ADAPTED TO WRAP THE WEB-LIKE MATERIAL AROUND A CORE TO FORM A CONVOLUTE WOUND STRUCTURE, 3. A WHEEL STRUCTURE BEARING PACKAGES OF HOLLOW FILAMENT PERMEATION SEPARATION MEMBRANES AND ADAPTED TO WRAP THE HOLLOW FILAMENT MEMBRANES AROUND THE PLANAR WEB-LIKE MATERIAL AS THE WHEEL ROTATES AND THE WEB-LIKE MATERIAL IS UNROLLED BY THE WEBFEEDER AND WRAPPED AROUND THE CORE BY THE TAKEUP, 4. GUIDES ADAPTED TO SUPPORT THE TWO EDGES OF THE WEB-LIKE MATERIAL WITH EACH EDGE WRAPPED NOT LESS THAN ABOUT 180* AROUND A GUIDE, AND 5. GUIDES FOR THE FILAMENTS ADAPTED TO CAM THE FILAMENTS TO PREDETERMINED POSITIONS ON THE WEB-LIKE MATERIAL.

Description

Apr. 2, 1974 APPARATUS FOR- MAKING CONVOLUTE WOUND STRUCTURES 3,169,087 2/1965 Van Ness et a1 156/431 Primary ExaminerDaniel J. Fritsch [75] Inventors: Andrew Passmore Cope; Steven Andrew Cope, both of Wilmington, Del. [5 7] ABSTRACT [73] Assigneez L d Pom de Nemours and An improved apparatus for assembling a convolute Company, Wilmington, DBL wound structure suitable for use in making an element of a selectlve permeation separation device compnses [22] Filed: Sept. 24, 1971 [21] AppL N02 183 590 l. a web feeder adapted to unroll a web-like foraminousmaterial in substantially planar form,

US. a takeup adapted to wrap the web-like material 156/425, 156/438, around a core to form a convolute wound 156/439, 156/443, 156/446, 156/461, 156/495 structure, 1 f B319 1332b /02, B321? 31/00 3. a wheel structure bearing packages of hollow Fleld of Search .1 filament permeation eparation membranes and 156/ 87, 430, 436, adapted to wrap the hollow filament membranes 210/321, 494, 500 around the planar web-like material as the wheel rotates and the web-like material is unrolled by References Clted the web-feeder and wrapped around the core by UNITED STATES PATENTS the takeup, 3,690,465 9 1972 McGinnis et a1. 210 321 guides adapted to pp the two edges of the 1,195,949 8/1916 Harrison 156/172 web-like material with each g pp not 3,493,455 2/1970 LeBolt et al. 156/440 less than about 180 around a guide, and 3,041,230 6/1962 Diehl ..156/430 5. guides for the filaments adapted to cam the 1,460,949 Currier filaments to predetermined positions on the 1,990,849 2/1935 Wagon 156/441 b lik i l 3,112,897 12/1963 Eshbaugh et a1. 15'6/169 2,772,718 12/1956 Magnoson 156/439 8 Claims, 13 Drawing Figures 15 80 l n w 45 i j 11 n 4 ;z 5Q l 4V1, A 15 1 M 27 47 we 26 41 J X 1 7a; 1

57 v 0 11. I 45 ,0 o O I 6 M as 0 4-0 Z5 l A a PATENTEDAPR 2 I974 3,801,401

sum 2 0r 5 FIGlA H99 FIG. 10 r 17 INVENTORS ANDREW P. COPE STEVEN A. COPE BY g M ATTORNEY INVENTORS ANDREW F. COPE STEVEN A. COPE BY g mw ATTORNEY APR 21974 3,801,401

sum u or s INVENTORS ANDREW P COPE STEVEN A. COPE BY M ATTORNEY PATENTEDAPR 21.914 3,801 ,401 s'um 5 0r 5 FIGS INVENTORS ANDREW P COPE STEVEN A. COPE BY 8,9 Q. P

ATTORNEY APPARATUS FOR MAKING CONVOLUTE WOUND STRUCTURES BACKGROUND OF THE INVENTION the web being supported in a plane by web guides.

2. Description of the Prior Art The prior art describes several machines suitable for assembling convolute wound structures. These machines include a web-feeder adapted to unroll a web in planar form, a takeup adapted to roll the web around a core to form a convolute wound structure, and a means between the web-feeder and the takeup adapted to wrap filaments around the moving web. The means adapted for wrapping filaments around a web is usually a rotating wheel through the center aperture of which the web passes and upon which are mounted wound packages of filaments and filament guides adapted to unroll the filaments from the packages and to lead them toward the moving web as the wheel rotates. These machines, however, do not provide the uniformity of filament wrapping, freedom from filament-imperfections, freedom from damage to filaments during the wrapping operation about a web and freedom from damage during filament transporting after the wrapping operation, and the substantially wrinkle-free separating material which are required for the efficient assembly and use of the wound structures.

In the machines of Wagon U.S. Pat. No. 1,990,849 and of Carlson et al. U.S. Pat. No. 2,699,813, for instance, filaments are wrapped around a warp of filaments or a web as it moves overa mandrel slightly wider than the web, with the filaments being forced to slide on the exposed edges of the mandrel. These machines do not provide a tight wrapping of filaments because the thickness and width of the mandrels are larger than those of the web. They also damage hollow filament membranes sliding on the edges of the mandrels.

The machines of Harrison U.S. Pat. No. 1,195,951; Diehl U.S. Pat. No. 3,041,230; and Van Ness et al. U.S. Pat. No. 3,169,087 provide for wrapping filaments around two endless belts. These machines are incapable of providing an orderly or taut wrapping of filaments around the web. because the filaments are severed along a line distant from the edges of the web, thus the filaments can never be coextensive with the web in the crosswise direction; the surplus length of filament would cause them to become disarrayed (i.e., out of parallel with each other) after severing were it not for the fact that they are joined to the web throughout substantially the entire width and length by means of adhesives. However, use of area-wide adhesives is not tolerable in the present invention. The apparatus of Sheffield U.S. Pat. No. 3,332,824 is subject to somewhat similar disadvantages and, in addition, uses an auxiliary filament guide means which would subject substantially the entire length of filament to friction and damage. A further reason for the unsuitability of some of these prior art devices is that with deposition of adhesives in advance of winding, a thickening of the web-form material occurs resulting in a larger diameter wound package in which the filament density is lower than with the present invention.

In operating machines with filament guides mounted on a rotating wheel as described in several of the above-mentioned patents, it is found that the filaments are laid down on the web in an erratic pattern and not in a regular parallel array of constant thickness. For example, when the web is horizontal the filaments hang below the web in bunches, rather than individually. The filaments then accumulate in bunches in the convolute wound structure, making the filament layers of uneven thickness and uniformity. Such bunching of filaments reduces the efficiency of operation of such convolute wound structure elements in selective permeation separation apparatus.

The apparatus of this invention permits for the assembly of convolute wound devices with good uniformity of filament wrapping, substantially free from filament imperfections or damage and with little or no wrinkling of the web-like separating material.

SUMMARY OF THE INVENTION In summary this invention is directed to an improved apparatus for assembling a convolute wound structure, said apparatus comprising 1. a web-feeder a. supported by a frame and b. adapted to unroll a roll or web-like foraminous material in substantially planar form;

2. a takeup a. supported by the frame and b. driven and adapted to wrap the web-like material around a core to form a convolute wound structure; and

3. a wheel structure a. supported by the frame between the web-feeder and the takeup, with the web-like material passing through an aperture thereof,

b. bearing packages of hollow filaments, and

c. driven and adapted to wrap the hollow filaments around the substantially planar web-like material as the wheel rotates and the web-like material is unrolled by the web-feeder and wrapped around the core by the takeup;

the improvements consisting essentially of 1. guides a. supported by the frame,

b. extending through the aperture of the wheel structure, substantially coextensive with the edges of the web-like material, and

c. adapted to support the web-like material in substantially planar array, with each edge of the web-like material wrapped not less than about around a guide; and

2. guides for the filaments adapted to cam the filaments to a predetermined position on the edges of the web-like material wrapped around the web guides as the filaments are wrapped around the web-like material during the rotation of the wheel structure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of an apparatus for assembling a convolute wound structure suitable for use in a selective permeation separatory element.

FIG. 1A is a fragmentary isometric view of an alternate embodiment of the apparatus of FIG. 1.

FIG. 2 is an isometric view ofa portion of the apparatus of FIG. 1, showing a web feeder and web guide.

FIG. 3 is an elevational view showing the web guide and wheel of FIG. 1.

FIG. 3A is an enlarged view of the filament guide of FIG. 3.

FIG. 4 is an elevational view of part of the apparatus of FIG. 1, showing a resin applicator in greater detail.

FIG. 5 is a fragmentary isometric view of a web guide showing the web in a folded condition.

FIG. 6 is a fragmentary isometric view of a winder showing a slitter blade used for removal of a portion of the web.

FIG. 7 is a fragmentary isometric view of a web guide showing a chisel shaped end.

FIG. 7A is a fragmentary isometric view of a web guide showing a chisel shaped end which is flared outwardly at its tip.

FIG. 8 is an isometric view of a portion of an apparatus similar to that shown in FIG. 1 but with means for feeding and winding an additional layer of web-like material.

FIG. 9 is a schematic partial longitudinal crosssection of a permeation separatory element showing a foraminous tube in the center and a solid resin structure at one end only.

FIG. 10 is a diagrammatic longitudinal cross-section of a selective permeation separation device incorporating an element of the type shown in FIG. 9 which can be assembled with the improved apparatus of this invention.

DESCRIPTION OF THE INVENTION The design and method of operation of the improved apparatus of this invention can be better understood by reference to the drawings wherein FIG, 1 is an apparatus for making the preferred elements of a selective permeability separation device which generally comprises a frame 10, a web feeder 11, a wheel 12 carrying wound packages 13 of hollow filaments 14, a drive roll 15, a resin applicator l6 and a partially completed permeator 35 all of which will be described in greater detail.

The machine frame 10 supports the entire apparatus on a generally horizontal surface extending across which is a beam which carries a pair of posts 21 which carry another horizontal beam 22 thus forming an open frame 27 which surrounds the wheel 12; the latter is supported by a pair of flanged rollers 23 which are carried on bearings mounted on the beam 20 as shown in FIGS. 1 and 3. A similar roller 24 is mounted on the lower side of the beam 22 and engages the top of the wheel 12. One of the two lower rollers 23 is power driven by a chain 25 and a motor 26, the speed of which may be varied by means not shown thus making it possible to drive the wheel 12 and to vary its speed. I

Beyond the right side of the frame 27 and the wheel 12 is the web feeder 11 which comprises a pair of posts 28 which support a rotatable arbor 29 which, in turn, supports a convolute wound roll 30 of web-like mate rial. The roll 30 is rotatable clockwise as viewed in FIG. 1 to pay off web 31 horizontally in a plane which passes through the center of rotation of the wheel 12. Rotation of the roll 30 is resisted by a fabriostrap 61 wrapped around roll 30 and substantially eoextensive with the width of that roll. One end of the strap 61 is anchored to the top of the beam 33a and the opposite end, hanging downward carries a weight 60. (See FIG. 2). In an alternate construction shown in FIG. 1A, driven nip rolls 74, are used to meter the web and coact with a drive motor such as 63 in FIG. 1 to provide a controlled uniform web tension. The upper roll 74 is an idler, mounted on bearings and is spring or weight loaded against the web while the lower roll 75 is mounted in fixed bearings (not shown) and is driven by a drive 76 and a motor 77 which precisely controls the speed of the roll 75, and consequently exerts a preselected and controllable speed for the web 31. The web is guided by means of a pair of fixed, cantilevered

guides

32a, 32b shown best in FIG. 2. These are supported by means of a pair of

horizontal beams

33a, 33b which are secured at each end to the posts 28 being spaced, respectively, slightly above and slightly below the horizontal web 31 thus holding the

guides

32a and 32b above and below the web, respectively. The web guides each have diagonal braces 34 as shown in FIG. 3 to prevent them from being pulled horizontally toward the center of the web. The

guides

32a, 32b extend completely through the center aperature of the wheel 12 and at their free ends are chisel-shaped as shown in FIG. 7. In an alternate construction 7A, the tip of the chisel-shaped guide is flared outwardly on opposite sides of the machine to aid in forming a flattened crease in the web and to maintain tension in the web and the filaments in the transverse direction just prior to winding. The free guide ends lie in close proximity to the outer surface of the drive roll 15. Extending generally between the guides 32 is a horizontal, planar table 62 seen best in FIG. 3, which supports the central part of the web 31. In an alternate construction, not illustrated, the guide 32b can comprise the edge of the table 62 and a second plate can be used in place of guide 32a and brace 34. The drive roll 15 is journalled in bearings not shown in posts 36 which stand on the machine frame 10. These posts also support a pair of swing arms 37 on pivots 38 which arms carry a rotatable arbor which comprises a foraminous hollow tube 18 and a drive comprising a torque motor 63, pulleys 64 and belt 65, the tube 18 being adapted to receive a convolutely wound structure 35 as shown. In a preferred embodiment the axis of the tube 18 and of the wound structure 35 is situated about 45 counterclockwise from a vertical plane through the axis of the drive roll 15 which means that the web 31 carrying filaments l4 wraps the drive roll for 45 before entering the wound structure 35. This finite angle of wrap provides increased frictional engagement between the drive roll and the web 31 and permits the speed controlled drive roll 15 to control the speed of the web. The tension of the web is provided by the coaction between the torque motor 63 and the weight 60 and strap 61. The torque of the motor 63 is inversely proportional to motor speed over the normal operating range thus resulting in constant web tension. The drive roll 15 can be power driven such as by means of a belt or chain 39 and a variable speed motor 40.

The web 31 has a transverse width a few inches greater than the width across the outer surfaces of the cantilevered guides 32. Thus, as the web 31 is paid off the roll 30, and passes through the wheel 12, the two edges of the web are caused to wrap for not less than about 180 around each outer peripheral surface of the guides 32 under the urging of the filaments 14 as seen best in FIG. 3; the purpose for this will be discussed further below.

Situated on one face of the wheel 12 are packages 13 of hollow filaments 14 obtained from conventional fiber spinning operations such as described in US. Pat. No. 3,442,002. The cores of the packages are preferably nonrotatably supported inside open-ended cannisters 67 on suitable pins or chucks not shown which are carried by the wheel 12. A post 41 stands next to each package 13, being supported by the wheel 12, and carries a yarn guide 42 spaced from the end of the packages which permits over-end removal of the filaments 14 when tension is applied thereto. A single package 13 or a plurality of packages may be used depending on the desired rate of utilization or laydown of filaments. On each post 41 is a magnetic hysterisis type brake 66 for exerting a preselected level of tension in the filaments as they advance around the pulley 66a on the brake 66. Fixed filament guides 70 made of round wire are used on the guides 32 as shown in FIGS. 1, 3 and 4. As shown in FIG. 3, and the enlarged section FIG. 3A, the foot of the filament guide 70 is anchored to the inner face of each web guide 32, clear of the edge of the web 31. The remainder of the filament guide encircles the bar 32 for about 270, then extends inward and upward in a generally straight line, the latter being inclined backward, i.e., toward the roll 30, by about 30 tothe vertical as seen in FIG. 4. The left edge of the portion of the filament guide 70 that encircles the web guide 32 is located slightly to the left of the plane 71 swept by the filaments 14 as they depart from the pulley 66a of the brake 66. Thus, the guide 70 is adapted to cam the filaments to a known position on the guides 32 and the web 31.

Extending transversely between the left part of the posts 36 is a horizontal beam 43 which optionally can support a resin applicator 16 comprising pivotally mounted swing arms 44 which carry a short, e.g., 2 to 4 inch roller 45 and a doctor blade 46 (See FIG. 4). The lower edge of the doctor blade is spaced from the perimeter of the roller 45, and the blade 46 and the roller form a vee-trough which carries a supply of viscous adhesive material 47, such as uncured epoxy resin. The roller rests initially on the bare tube 18 and later on the surface of a convolute wound structure to be rotated thereby, being thus adapted to carry a metered quantity of adhesive 47 counterclockwise around the perimeter of the roller 45 to be deposited on the structure 35 below. Also mounted on the beam 43 is a pair of swing arms 79 which carry a rotatable pressure roll 80 which may be covered with foam rubber and which rests on the wound structure.

Initially the web 31 is withdrawn from the roll 30 by hand in planar form, is strung between the beams 33, through the interior of the wheel 12 and across the table 62 and the guides 32, under the urging of the filaments 14 where the two edges of the web are wrapped partially about each of the guides, as shown in FIG. 3,

but not less than about on each. The web is manually advanced toward the bare tube 18 and as it departs from the chisel-shaped terminal ends of the guides 32 is folded upon itself, as shown in FIG. 5, being retained in the folded form by the tension in the web 31 holding it against the drive roll 15. The leading edge of the folded web is wrapped about the tube 18 a little in excess of one full turn so as to entrap it and secure it thereto. If it is desired to avoid a double thickness of material, as an alternative, the web 31 may be folded upon itself, as described, but in addition may be slit continuously at the site of the crease by means of a fixed circular blade 48 situated with its cutting edge very close to the nip between the tube 18, or the convolute wound structure, and the surface of the drive roll 15. An additional advantage in this is that the adhesive present at the edge of the web 31 and received from applicator 16 may tend to bleed through the web and be deposited on the drive rolls. However, if selvage 49 underlies the web 31 at this point, the bleed-through will be received by the selvage and subsequently discarded as shown generally in FIG. 6, the selvage 49 being drawn axially away from the drive roll by a puller not shown.

Filaments 14 are deposited by securing their leading ends in the nip formed by the web 31 and the tube 18 on the wound structure 35, and then by rotating the wheel 12, thus withdrawing them from the packages 13 around the pulley of the brakes 66. The filaments are laid on the web 31 transversely in a kind of helical path since the web is being advanced at a constant velocity by means described hereinbefore. The filaments may be laid side-by-side or in spaced or even in overlapping relationship depending upon the preselected relative velocity of the wheel 12 and the web 31.

The filaments extend around the curving edge portion of the web which overlies the web guides 32 for not less than about 180", thus they are substantially out of contact with these bars from which it will be seen that slippage of the filaments lengthwise along the guides 32 and concomitant damage from this source is avoided altogether. Since the web 31 is wrapped in a kind of S" form about the guides 32 (FIG. 3) and since the fil-.

aments are being subjected to a slight tensioning effect due to the use of the brakes 66 which tension is exerted in the direction in which the tails of the 8 point, it will be seen that the web edges will each tend to be urged clockwise around the respective guides 32 thus making the web 31 taut in the transverse direction in the expanse between the bars and thus maintaining it in a planar condition.

From the foregoing it will be seen that the filament 14 is laid on the top and bottom of the web 31 as a kind of conveyor belt; the filaments and the web progress into the nip between the hollow foraminous tube 18 or the nip between the convolutely wound structure and the perimeter of the drive roll 15 at which nip they become trapped, forming the successive layers of the convolutely wound structure being secured or encapsulated at one or more sites by adhesive resin being deposited such as by means of applicator 16. The resin is supplied over a limited length such as 2 to 4 inches, and at such a rate as to completely penetrate and fill the interstices between filaments 14 over that length. Similarly the spaces between the filaments and the web 31 and the apertures within the foraminous web are filled in effect forming a solid structure when the resin has cured, save for the spaces inside the hollow filaments which, of course, are not penetrated by the resin.

When the wound structure reaches a desired size, it is removed from the apparatus after which the resin is permitted to cure. Next, the convolutely wound structure, the resin, and all of the potted materials are machined as described below so as to cut and expose the hollow interior portions of the filaments, forming a tube sheet structure as shown in cross section in FIG. 9.

As described above, filaments 14 are laid transversely on the web 31 by means of the rotating wheel 12. However, because the web is moving, the lay of the filaments is not precisely at 90 but it is at an angle, the magnitude of which is contingent on web speed compared to wheel speed. With constant web speed, as the wheel speed is decreased, the angle A shown in FIG. 1 will become smaller with the effect that filaments on the top and bottom of the web 31 have opposite lay at a small angle such as 2 to 5 or more relative to each other. The result is that the filaments in contiguous layers in wound structure 35 will cross each other at about the same angle. While this is not necessarily of major importance, the filament crossovers could cause injury to filaments particularly if a tightly wound structure 35 is desired. This can be avoided by use of the apparatus of FIG. 8 in which an additional web 31a is introduced near the drive roll, passes around an idler or guide roll 59 beneath the web 31 and the lower run of filaments and is subsequently caught in the nip between the drive roll and the lower run of filaments. Thus, in the convolute wound structure 35 the second web 31a will be seen to lie between successively wound layers of upper and lower filaments, thereby separating them from each other. The use of an additional web 31a also serves to support the lower run of filaments as they approach the nip in the winding operation in the event that they tend to sag or in the event that the folded edge of the web 31 and the filaments 14 are slit as shown in FIG. 6 and described above.

It will be recognized that if a different rate of laydown offilaments is desired without removing or adding packages 13 to the wheel 12, the rate of laydown can be altered simply by changing the wheel speed with a constant web speed. For example, it may be desired to have a greater density of filaments in the outer portion of the wound structure 35 in which case the wheel speed can be increased as the structure is prepared.

If desired, a revolution counter 68 can be mounted on the beam 22, or other, convenient places, to be actuated by a cam 69 on the wheel 12. Thus, the total number of revolutions of the wheel 12 can be observed as a measure of the total number of filaments emplaced in a given permeator assembly, and if desired, equipment can be incorporated to automatically cut the filaments 14 after a predetermined number of revolutions of the wheel 12. For convenience the counter can be manually resettable to zero. If desired, a filament detector in the form of a light source and photo-electric cell (neither shown) may be employed to detect breakage or absence of filament at the point of laydown and, by means of suitable electrical circuits (not shown) to shut downthe entire machine if filaments are not being fed.

As described, the selective permeation separation elements assembled with the apparatus of this invention include separating layers of web-like foraminous material between layers of hollow filament membranes. These separating layers of foraminous material restrict movement and nesting of the adjacent hollow filament membranes by preventing their contact and by reducing their freedom of movement perpendicular to their length. Preferably the foraminous material has uneven surfaces so as to touch only a small fraction of the adjacent filament surfaces and thereby to reduce only insignificantly the effective membrane area. The separating material must be thin so that it does not excessively reduce the fraction of the volume of the separatory element which is available for the hollow filament membranes and correspondingly the membrane area which can be achieved in a given volume. It must be foraminous in order to permit flow of the fluid feed mixture through the permeation separatory element.

Foraminous materials suitable for use in the fabrication of the separatory elements can be any material which is compatible with the fluid mixture to be separated and with the materials of which the hollow filament membranes are made, and which is sufficiently porous to permit penetration and effective sealing by adhesive materials. Synthetic polymeric materials are preferred because of their low cost and ease of fabrication into suitable shapes and forms. These foraminous materials can be porous flexible solids such as sintered metals or porous plastic sheets; pervious fibrous materials such as paper, cloth or nonwoven cloth-like materials; perforated films; or any other similar material. The preferred materials are in general web-like, in that they are flexible structures of relatively large area compared to their thickness, composed of fibrous elements, and with the general properties of cloth and paper. Particularly preferred structures include the spunbonded structures described by Shealy et al. in the Textile Research Journal, Volume 35, pages 322 to 329 (1965) and Volume 38, pages 7 to 15 (1968).

Hollow filament membranes suitable for use in the selective permeation separation elements assembled with the apparatus of this invention are those which under operating conditions are self-supporting with a reasonable flux. Thus, the filament wall thickness must be small enough to permit a practical flow of permeate through the wall and large enough to give a thickness to diameter ratio characteristic of self-supporting filaments. Suitable hollow filament membranes can be of different structures prepared by appropriate techniques and particularly adapted for particular separation processes as is known in the art. They can be hollow polymeric fibers prepared by melt spinning as described in the art, as for example by Breen et al. in US. Pat. No. 2,999,296. Such hollow filaments can be extracted or otherwise treated chemically or physically to improve their membrane properties as described for example by Mahon in U.S. Pat. No. 3,423,491 and by Cescon et al. in US. Pat. No. 3,551,331. Other hollow filament membranes particularly suited for use in the elements and devices of this invention are prepared by solution spinning as described by Richter et al. in US. Pat. No. 3,567,632.

The composition of the hollow filaments will depend largely upon the fluid composition to be separated and include polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, polyhexamethylene adipamide, copolymers of tetrafluoroethylene and hexafluoropropylene, cellulose acetate, ethyl cellulose, polystyrene, copolymers of butadiene and styrene, cellulose esters, cellulose ethers, acrylonitriles, polyvinyl formals and butyrals, polyolefins, polyurethanes, polyamides and the like.

The filament membrane layers can, theoretically at least, be a single filament thick, with all filaments in a given layer in substantially parallel alignment. In practice, the filament layers are effectively more than a single filament thick and are conveniently formed of multifilament yarns such as are produced by multifilament spinnerets. Thus, the filament membrane layers can be arrays of 1 to about 25 multifilament yarns in overlapping but substantially parallel alignment. Arrays up to about 0.25 inch thick of hollow filaments having properties typical of textile fibers are useful in practice.

crons to no more than three times the outside diameter.

of the individual filaments.

The selective permeation separation elements assembled with the apparatus of this invention also comprises a resinous tube sheet structure through which ends of the hollow filament membranes extend. This structure can be formed, for example, by placing the extremes of the hollow filament membranes and optionally the associated foraminous separating material in a mold and potting" with a setting'resin, as described by Mahon in U.S. Pat. No. 3,228,877 or as described by Maxwell et al. in U.S. Pat. No. 3,339,341, or by impregnating the alternating layers of hollow filament membranes and foraminous material with a setting resin, using techniques similar to those described by McLain in U.S.-Pat. No. 3,422,008 or by Strand in U.S. Pat. No. 3,342,729.

The permeation separatory elements described herein can be used for the separation of components from fluid mixtures, whether they be liquid, vapor, gas, or a combination of these. Suitable processes include any of the separation processes commonly known, for example, as selective permeation, mass diffusion, gaseous diffusion, molecular effusion, dialysis, piezodialysis, thermodialysis, osmosis, reverse osmosis, thermoosmosis, ultrafiltration, and hyperfiltration.

The function and structure of the preferred elements of a selective permeation separation apparatus which can be economically and efficiently assembled with the improved apparatus of this invention can be better understood by reference to FIGS. 9 and 10. FIG. 9 shows a convolute wound structure such as can be made with this apparatus with an associated tube sheet structure in a separation element in which the cured resin tube sheet 19 contains succesive layers of hollow filament membranes 14, the edge of convolutely wound web separating material 31, and the foraminous hollow tube 18. In this embodiment, the end of the tube 18 is closed with a plug 50, and the central, cast-in aperture in the resinous tube sheet is potted with fresh resin 19a. The opposite end of the tube 18 is joined to a nonpervious tubular conduit 51 which is adapted to introduce into or remove from the foraminous tube 18 the fluid mixture to be separated. The opposite portions of the filaments 14 in this embodiment form hairpin bends 52 which generally extend around the folded edge portions of the webs 31 and then extend through the annulus formed on the opposite side of the web 31 and through the cured resin tube sheet 19 from which they emerge, so that the interiors of both ends of the hollow filament membranes are open for fluid flow.

Any of the convolutely wound permeation separation element embodiments described herein are suitable for use in the permeation separation device such as that shown diagrammatically in FIG. 10, which generally comprises a shell 53, usually tubular in form, closed at each end by heads 53a and 53b, respectively. The heads may be secured to the shell 53 in any conventional fashion, such as by welding, by snap rings (shown), or by bolting, sealing being affected by means of flat gaskets or elastomeric O-rings or the like. The convolute wound structure is installed in the shell 53 with a sealing means, such as an O-ring 58, between the cured resin 19 and the shell 53. The nonpervious conduit 51 of the structure extends through a suitable aperture in the head 53a and is sealed relative thereto. An aperture 57 in the shell 53 serves to admit feed fluid while reject fluid emerges from the conduit 51. Product or permeate flows through the interior of the hollow filaments l4 and thence to the head space 55 where it is collected, emerging from the apparatus via aperture 56. In this embodiment it will be seen that the feed fluid entering aperture 57 flows generally radially inward through successive layers of the convolute wound web 31 and amongst the generally parallel filaments 14.

The following example illustrated this invention.

EXAMPLE 1 A permeator separatory element was assembled using, as the foraminous web material, a 30 inch wide sheet of spunbonded polypropylene non-woven fabric with a basis weight of 2.5 ounces per square yard and a thickness of 0.01 inch and used as the membranes were hollow filaments made of an aromatic polyamide containing sulfonic acid groups by procedures described by Richter et al., in U.S. Pat. No. 3,567,632. The filaments were in the form of filament 3,000 denier yarns. The fabricating equipment used was that of FIG. 1 and was operated for 10 minutes at a web speed of 12 inches per minute, during which the hollow filament yarns from 12 bobbins were wrapped on the web at a wheel speed of 18 revolutions per minute. The resulting wrapped web was wound as it was made onto a 32 inch long porous polyethylene tube having an inside diameter of 0.4 inch, an outside diameter of 1.0 inch, and uniformly covered with pores of about 10 microns diameter. Epoxy resin was applied by hand brushing during the winding operation to encapsulate the hollow filaments and to form the solid structure for the tube sheet end of the unit. After removal from the machine, the recessed end of the porous tube at the tube sheet end of the unit was plugged, the central recess was filled with resin and a 3 inch long, one-inch thick thick layer of resin was cast onto the perimeter of the tube sheet structure. After the resin had hardened, the face of the tube sheet was cut off to open the ends of the hollow filament membranes to fluid flow and the newly cast outer peripheral surface was machined to accept an O-ring. The porous tube at the opposite end was cut flush with the filament ends and a nonporous polyethylene tube was then joined and sealed to the porous tube. A removable restraining collar mold was placed around the end, and the end was covered with resin to encapsulate the U turns of the filaments and the end of the porous tube with the nonporous tube attached. The resulting separatory element was about 3.9 inches in outside diameter, contained about 600,000 filaments, each with an effective length of about 25 inches, and contained a total membrane area of about 1,300 square feet. When installed in a shell like that shown in FIG. 10, this element effectively desalts brackish waters under reverse osmosis conditions for a significantly longer time than a similar element without the layers of foraminous web material.

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:

1. An improved apparatus for assembling a convolute wound structure, said apparatus comprising 1. a web-feeder a. supported by a frame and b. adapted to unroll a roll of web-like foraminous material in substantially planar array;

3. a wheel structure a. supported by the frame between the web-feeder and the takeup, positioned so that the web-like material passes through the aperture thereof when unrolled by the web-feeder and wrapped around the core by the takeup,

b. adapted to bear packages of hollow filaments,

and

c. driven and adapted to wrap the hollow filaments around the web-like material as the wheel rotates and the web-like material is unrolled by the webfeeder, passed through the aperture of the wheel structure, and wrapped around the core by the takeup;

the improvements consisting essentially of 1. web guides a. supported by the frame,

b. extending through the aperture of the wheel structure, substantially coextensive with the edges of the web-like material as the web-like material passes through the aperture of the wheel structure in substantially planar array, and

c. adapted to support the web-like material in substantially planar array, with each edge of the web-like material wrapped not less than about 180 around a guide; and

2. guides for the filaments adapted to cam the filaments to predetermined positions on the web guides and to bend the filaments around each of the web guides for about 180 during the rotation of the wheel structure, the filaments and web being maintained in the bent condition, and wherein the guides for the filaments are:

a. made of wire, each with a first end and a second end,

b. each first end anchored clear of web-like material to a web guide,

c. each encircling a web guide and spaced there from extending about 270 in the direction opposite of wrapping of filaments,

d. each second end extending toward the roll of web-like material.

2. The apparatus of claim 1 wherein the ends of the web guides taper to a chisel edge and the outwardly facing portions are flared.

3. The apparatus of claim 1 wherein means are provided for feeding the web at a controlled rate and tension.

4. The apparatus of claim 1 wherein a pressure roll rests on top of the wound structure and rotates with the wound structure.

5. The apparatus of claim 1 wherein means are provided for applying adhesive to the wound structure.

6. The apparatus of claim 1 wherein the takeup drive comprises a torque motor drivingly engaged with a core for the convolute wound structure.

7. The apparatus of claim 6 wherein the output torque of the torque motor is inversely proportional to the output speed of said motor.

8. A method of assembling a convolute wound structure in which a web-like material is wrapped about a foraminous core in discrete layers each containing cross-laid hollow filaments, the method comprising:

1. feeding a web-like material,

a. in substantially planar condition, and

b. at a controlled rate and tension;

2. taking up the web-like material,

a. in a convolute winding on a foraminous core,

while b. exerting torque on the core in the winding direction in inverse relationship to its rotational speed;

3. guiding the advancing web-like material, on web guides, each guide substantially coextensive with an edge of the web in its planar condition; 4. wrapping hollow filaments about the substantially planar web, a. substantially at to an edge of the web, by b. orbiting a filament supply around said web while simultaneously bending the edges of the web into wrapping engagement with the web guides sufficient to preclude all direct contact between filament and web guides, c. under controlled filament tension; and 5. flattening the bent edge portions of the web and of the filament simultaneously, a. to form a crease, while b. guiding the web on tapering terminal end portions of the fixed web guides.

Claims

1. A WEB FEEDER ADAPTED TO UNROLL A WEB-LIKE FORMANIOUS MATERIAL IN SUBSTANTIALLY PLANAR FORM,

2. A TAKEUP ADAPTED TO WRAP THE WEB-LIKE MATERIAL AROUND A CORE TO FORM A CONVOLUTE WOUND STRUCTURE

2. taking up the web-like material, a. in a convolute winding on a foraminous core, while b. exerting torque on the core in the winding direction in inverse relationship to its rotational speed;

2. guides for the filaments adapted to cam the filaments to predetermined positions on the web guides and to bend the filaments around each of the web guides for about 180* during the rotation of the wheel structure, the filaments and web being maintained in the bent condition, and wherein the guides for the filaments are: a. made of wire, each with a first end and a second end, b. each first end anchored clear of web-like material to a web guide, c. each encircling a web guide and spaced therefrom extending about 270* in the direction opposite of wrapping of filaments, d. each second end extending toward the roll of web-like material.

3. a wheel structure a. supported by the frame between the web-feeder and the takeup, positioned so that the web-like material passes through the aperture thereof when unrolled by the web-feeder and wrapped around the core by the takeup, b. adapted to bear packages of hollow filaments, and c. driven and adapted to wrap the hollow filaments around the web-like material as the wheel rotates and the web-like material is unrolled by the web-feeder, passed through the aperture of the wheel structure, and wrapped around the core by the takeup; the improvements consisting essentially of

3. guiding the advancing web-like material, on web guides, each guide substantially coextensive with an edge of the web in its planar condition;

3. A WHEEL STRUCTURE BEARING PACKAGES OF HOLLOW FILAMENT PERMEATION SEPARATION MEMBRANES AND ADAPTED TO WRAP THE HOLLOW FLAMENT MEMBRANES AROUND THE PLANAR WEBLIKE MATERIAL AS THE WHEEL ROTATES AND THE WEB-LIKE MATERIAL IS UNROLLED BY THE WEB-FEEDER AND WRAPPED AROUND THE CORE BY THE TAKEUP,

4. GUIDES ADAPTED TO SUPPORT THE TWO EDGES OF THE WEB-LIKE MATERIAL WITH EACH EDGE WRAPPED NOT LESS THAN ABOUT 180* AROUND A GUIDE, AND

4. wrapping hollow filaments about the substantially planar web, a. substantially at 90* to an edge of the web, by b. orbiting a filament supply around said web while simultaneously bending the edges of the web into wrapping engagement with the web guides sufficient to preclude all direct contact between filament and web guides, c. under controlled filament tension; and

5. flattening the bent edge portions of the web and of the filament simultaneously, a. to form a crease, while b. guiding the web on tapering terminal end portions of the fixed web guides.

5. GUIDES FOR THE FILAMENTS ADAPTED TO CAM THE FILAMENTS TO PREDETERMINED POSITIONS ON THE WEB-LIKE MATERIAL.