US2039312A - Reenforced carded web - Google Patents

Description

y 1936- J. H. GOLDMAN 2,039,312

REENFORCED CARDED WEB Filed March 15, 1955 Patented May 5, 1936 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to webs of carded fibers, that is, webs wherein the fibers have decided directional lay by virtue of the carding and/or combing operations that they have undergone in being transformed from a loose conglomerate or tangled mass into a web or sheet of substantially uniform thickness. While not limited thereto, the present invention deals more particularly with carded cotton webs such as are used for a variety of purposes, such as surgical dressing, sponge or absorptive media for wiping or mopping up liquid or pastes, e. g., medicaments, from the body, filter septa, paddings or stumngs for such structures as mattresses and pillows.

The usual carded cotton web is faulty in that it tends to "lint" or shed fibers by reason of the fact that its fibers exist essentially in an individualized state, cohesion of the fibers in the web being ascribable largely to such fiber interfelting or matting as has survived the combing or fiberalining activity of the carding and/or combing machines. This residual cohesiveness between the fibers in the carded web is quite low, insomuch that it is a comparatively easy matter to pluck out fibers from the web or to rupture it. Accordingly, when a carded web is used for wiping the body or other surfaces, there is a tendency to deposit lint" or fuzz on ,the wiped surfaces; and this tendency is accentuated when liquid or pasty materials are being mopped up, since such integrity as the web has is reduced by a wetting of its fibers and since there is a tendency for the fibers loosely integrated with the web to part from the web when the material being mopped up has even a low degree of adhesiveness, as is true not only of paste-like or salvelike materials, such as cold cream, but also'ih some measure of such lowly viscous liquids as water. However, carded cotton webs have various desirable qualities for their intended purposes, including high fiuillness or voluminosity per unit weight of fiber, high absorptivity, softness or compressibility, and pliancy, all of which qualities render such webs satisfactory for purposes for which other fibrous webs, such as even absorbent papers, are quite unsatisfactory.

Generally stated, the objective of the present invention is to reenforce. carded webs of fiber,

especially carded cotton webs to do away with aforementioned desirable properties realized from Before entering into a discussion of such webs. the mode of accomplishment of this objective, it

is well to consider the structural make-up of a carded cotton web. In producing such a web, it is the customary practice to employ cotton fiber of various staple or average fiber length, it being preferable, however, to use as long a cotton staple as available, since the longer the staple, the better the resulting web. However, the cotton staple should properly be of a length of at least about since shorter staple does not comport with proper carding and/or combing or the realization of satisfactory webs. As a result of carding and/or combing cotton of adequate staple or average fiber length, one arrives at a carded web wherein the cotton fibers have distinct directional lay. Indeed, the fibers of the carded web exist essentially in parallelism, their lay being in the direction of the length or longitudinal dimension of the web coming from the carding machine. By virtue of such pronounced directional lay of the fibers, it is especially easy to rupture or tear apart the carded web by exerting tension laterally of the web, since there are relatively few fibers that serve to integrate or reenforce the web laterally, although, as hereinbefore indicated,.the web is weak as a whole, that is, can also be readily torn by longitudinal tensions. In order to offset the lack of lateral tying or integrating fibers in a carded web, it is sometimes the practice to ply into a single sheet a multiplicity of such webs with the substantial parallel fibers in one carded ply running substantially perpendicularly to the substantially parallel fibers in the adjacent carded ply. However, even such multi-ply webs are deficient in the respects already mentioned.

In accordance with the present invention, a carded web, either of unitary or multiaply structure, is reenforced by impregnation with a suitable binder along narrow lines spaced apart a distance which, at its maximum, is preferably slightly less than the average fiber length of the fibers constituting the web. In the case of a unitary or single ply web, the lines of impregnant may run only laterally of therweb, that is, in a direction perpendicular to the fiber lay. By so binding together the fibers locally, it is possible to do away with the original structural weakness of the web without materially sacrificing its valuable properties, since the lines of reinforcement need occupy but a small fraction of the total area of the web and yet firmly integrate or tie together substantially all of the longitudinally lying fibers of the web. Of course, by providing merely lateral lines or localities of binder reenforcement, the small fraction of laterally lying fibers may escape bonding action wherefore, it is ,preferable that there be lines of binder reenforcement longitudinally as well as laterally of the web so that substantially all of the laterally as well as longitudinally lying fibers may be bonded or tied together. when applying the principles of the present invention to a multi-ply carded web wherein the fibers of one carded ply lie substantially perpendicularly to the fibers of the adjacent carded ply, it is possible to secure the advantages of the present invention either by criss-crossing lines, of binder penetrating the bodies of both plies or by introducing or infusing the binder in each ply along lines running perpendicularly to the fiber lay in each ply, in which latter case the reenforcing lines as well as the fiber lay in one ply are perpendicular to the reenforcing lines and fiber lay in the adjacent ply.

With the foregoing and other features in view, the present invention will now be described in greater detail with reference to the accompanying drawin wherein,-

Figure 1 illustrates in plan view a reenforced web of carded fibers embodying the present invention.

Figure 2 is a longitudinal section through such reenforced web.

Figure 3 shows in plan view another embodiment of the present invention.

Figure 4 is a similar view of a reenforced multi-ply web embodying the present invention, a corner fragment of the upper ply being lifted away to show the crossing fiber lay of the lower Ply.

Figure 5 shows diagrammatically and conventionally apparatus for reenforcing a web.

Figure 6 illustrates one form of applicator roll that may be used in applying the reenforcing binder to the web.

As shown in Figure l, a carded web I0 may be treated to carry binder reenforcement therein in regularly recurring lines running transversely thereof, that is, in a direction substantially perpendicular to the fiber lay therein. The web may be composed of cotton fibers of a staple or average fiber length ranging all the way from a minimum of say, about to such high staple or average fiber lengths as exist in the highest grades of cotton, such as Egyptian and Sea Island. Preparatory to carding, the cotton may be suitably treated, as by boiling in alkaline liquors, to remove natural waxes, resins, and oils therefrom and thus to purify it and increase its absorbency. As already indicated, the lines of binder reenforcement should be spaced a distance which at most is preferably slightly less than the average fiber length of the particular grade of cotton constituting the web. Of course, any spacing less than this maximum might be adopted, but inasmuch as it is desired to preserve as much as possible the absorbency and other desirable qualities in the original web while adequately reenforcing it, it is preferable not only to keep the reenforcing lines of minimum width but also to use a minimum number of lines of reenforcement thin webs.

connection, it might be mentioned that I prefer to use binders of sufficiently high viscosity to result in minimum spread or diffustion of binder beyond the lines of application. Thus, such binders or adhesives as rubber latex, cellulose acetate or other cellulose ester solutions, resin solutions, and similar binders may be employed at a sufiiciently high concentration to be quite thick, to effect a tenacious local binding action on the fibers upon being dried or set, and to have low natural diffusing or migrating tendencies in the web. Because it is desirable to incorporate the binder throughout the body of the web and the comparatively viscous binders that are preferably employed do not naturally tend to penetrate deeply into the web, it may be necessary to squeeze or otherwise force the binder into the web body, as by using a binder-applicator roll having raised or projecting binder-applying portions which, as they deposit binder locally onto the web, also force or squeeze the binder into and throughout the body of the web. If desired, the projecting binder-applying portions may be cupped or recessed, as in intaglio printing, to minimize spread or diffusion of the binder from the loci of application, the cup or recess ridges pinching or locally compacting the web so as to diminish tendency for the binder to spread or diffuse beyond the pinched or locally compacted web portions. As shown in Figure 2, the web regions ll into and throughout which the binder has been squeezed are shown as being indented, since once the web has undergone sig nificant compression, it does not tend to recover fully its original thickness. Of course, the local .condensation or compression of the web along the lines II makes for added reenforcement of the web.

In a single ply carded web, the best reenforcement is realized when the lines of binder occur longitudinally as well as laterally of the web. Accordingly, as shown in Figure 3, the web may be binder-impregnated throughout its body along criss-crossing lines comprising the longitudinal reenforcing lines l2 as well as the transverse reenforcing lines I l, the spacing of both sets of reenforcing lines being accordant with the principles already enunciated.

Criss-crossing lines of binder reenforcement may also be applied advantageously to the multiply carded web depicted in Figure 4, wherein the upper carded ply [3 consists essentially of longitudinally extending fibers and the lower carded ply l4 consists essentially of laterally extending fibers, the lines of reenforcement preferably penetrating throughout the bodies of both plies. Such a reenforced multi-ply structure is especially tough; and it is eminently satisfactory for use as a filtering septum in the filtration of aqueous and other liquids tending to disintegrate an unreenforced carded cotton web. For such purpose it is, of course, important that the reenforcing binder be substantially unaffected by the liquid being filtered, water-insoluble binders, such as rubber and cellulose esters being useful for webs to be used in filtering water and aqueous liquids.

The reenforced webs of the present invention may be of varying thicknesses, depending upon the use to which they are to be put. Thus, for such purpose as filter septa, the reenforced webs of the present invention may be comparatively thin and range from, say, about 0.005 to 0.015 inch thickness. It is a comparatively easy matter to realize penetration of binder through such Indeed, in the case of such thin webs,

the binder-applicator roll or other applying instrumentality need not exert pressure on the web on the localities receiving the binder even when the'binder is quite viscous, since even viscous binders will tend to diffuse or spread before setting a distance equal to the web thickness. However, the reenforced webs of the present invention may assume considerable thickness, for instance, the thickness of bats or sheets such as are requisite for stufiing or padding purposes. In such case, it is desirable to squeeze or otherwise force the binder throughout the web body in order to effect the desired localized binding action while at the same time using binders of sufliciently high viscosity to obviate undesirable natural lateral diffusion. In the case of exceedingly thick battings or pads comprising a multiplicity of carded plies, reenforcement of the individual plies according to the present invention may be effected before they are matted or otherwise built up into the finished thick structure.

For the purpose of effecting a reenforcement of a carded web, I may employ such instrumentalities as are diagrammatically depicted in Figure 5. As shown therein, carded web W may be progressively withdrawn from a roll l and fed into the nip of a pair of rolls IS, the lower roll of which is the applicator roll and the upper roll of which serves to back up the web as binder is being forced locally and throughout the web body. As shown in Figure 6, the periphery of the applicator roll may assume the form of a grid of criss-crossing, dull-edged blades l1 welded or otherwise secured together and projecting from the body or core of the roll la in which they may be suitably embedded or fastened. The dull edges of the blades l1 may lie in the same cylindrical surface and receive a coating of the binder or adhesive from a kissing roll l9, which may rotate partially submerged in a bath 20 of the binder and which may progressively transfer a film of the binder of suitable thickness to the blade edges as such edges progressively contact with the roll IS. The peripheral portion of the upper roll I6 is preferably resilient or yielding, being composed, for instance, of such material as rubber, so as to permit the dull blade edges to dig or bite into the web and thus to squeeze the binder throughout the body of the web without cutting or cleaving apart the fibers. The binder-impregnated web progressively emerging from the nip of the rolls I6 may be dried as by passage over a bank of drier drums 2| whence it may be delivered to a wind-up roll 22. The dried, reenforced web may then be put through such other operations as cutting into filter disks, surgical bandages, surgical wadding, or, if desired, plied into thick pads such as are useful for stufiing mattresses, furniture, etc.

An important sphere of use of the reenforced web of the present invention is as a filtering septum. In filtering various liquids of aqueous and other varieties, it has heretofore sometimes been the practice to use the usual carded webs of commerce as filtering media. However, the usual carded webs, even when they are of multi-ply structure with the fibers of one ply running perpcndicularly to the fibers of the adjacent ply, tend to disintegrate and lose their filtering effectiveness in the course of filtering operation, that is, after they have undergone the soaking and fiber-dislodging action of the liquid being filtered. In order to prevent impairment of the usual carded webs of commerce as filtering media, it has sometimes been the practice to back and/or face such webs with cheesecloth or equivalent textile fabric.

Not only is this an expensive. expedient, but it does not prevent displacement of the carded fibers and the concomitant loss of filtering efiectiveness of the webs. The reenforced webs of the present invention not only require no woven backing or facing fabrics to remain substantially intact during a liquid-filtering operation, but substantially all of the web fibers are tied together in such a way that the fibers do not tend to become dislodged from their original positions. The reenforced webs of the present invention hence do not lose in significant measure their filtering effectiveness. Moreover, inasmuch as only a small fraction of the total area of the webs of the present invention is binder-treated, the filtering capacity of the webs is not materially less than that of the original or non-reenforced webs. It might be further observed that the cost of reenforcing webs as herein described is decidedly lower than the cost entailed in providing woven fabric backings and/or facings for carded webs.

Another use for reenforced web of the present invention is as a bandage material, that is, a material to be used in lieu of the usual surgical gauze in the dressing of wounds. Because of its tenacity, the bandage material of the present invention can, without tending to disintegrate, be wrapped around a wound which releases blood; and such bandage material may even be wetted down with liquid medicaments, wound-selves, or the like, without rupturing or losing the original tightness of wrap.

While the foregoing description emphasizes the utility of the present invention as applied to carded cotton webs, it will be appreciated that the present invention extends to carded webs of fibers other than cottons, for instance, sisal, fiax,

- hemp, jute, silk, or other fibrous material of sufficiently long average fiber length to lend itself to satisfactory carding and/or combing operations. The reenforoing binder may be any one of the large variety of binders or adhesives; and while I have hereinbefore indicated the desirability of using for some purposes water-insoluble binders, nevertheless, for other purposes, one may use such water-soluble binders as starch paste, glue, gum arabic, etc. In addition to the Water-insoluble binders hereinbefore mentioned as being useful, I might name such others as viscose, phenol condensation products and other artificial resins, such as the vinyl resins, rubber cements, thermoplastic gums or waxes, etc. As already indicated, no matter what binder is employed, it is locally distributed or infused into the body of the web so as to tie down or fix substantially all the fibers of the web while substantially or to all practical intents and purposes preserving the desiderata of the original unimpregnated web.

I am aware of the fact that it has been proposed to reenforce a paper sheet with binder applied thereto along criss-crossing lines. Aside from the fact that the characteristics as a whole of paper, including fiber lay therein, are quite different from those of carded webs, such as carded cotton webs, it is to be noted that papermaking fibers are comparatively exceedingly short, since, for fabricating a satisfactory paper sheet, that is, a web of substantially uniform texture and thickness, it is necessary to employ fibers such as typified by spruce sulphite pulp or spruce kraft pulp having an average fiber length in the order of magnitude of about 1.5 millimeters. On the other hand, it is impossible to form a satisfactory carded web from such short fibers, since such fibers do not respond at all to the combing action binder length orat least about theydo not yield a carded web of uniform texture and thickness.

,From the foregoing, it can be seen that one cannot bond together substantially all of. the fibers in a paper sheet without, in efi'ect, impregnating thewhole body or a large fraction of the sheet, for it is physicallyirnpossible toapply binder t'o a paper sheetat sufilciently close intervals-to ensure bonding. of substantially all of the fibers without at the same time causing a spread vof substantially throughout the entire paper body or a large fraction thereof. Contrariwise, it is quite feasible and, in fact, eminently practicable totie together substantially all of the comparatively long fibers of a carded web by binder infused locally into the body of the-web and occupying only a small fraction of the total area of the web. r

The principles of the present invention may be extended to unwoven fibrous webs or sheets other than carded ones, for instance, garnetted or bats of cotton or other fiber, airlaid or waterlaid webs of fiber, etc., wherein the fibers are of an average length similar to or approximating that of the fibers in carded webs but are entangled or interielted with heterogeneous or promiscuous fiber' arrangement or lay. By introducing into such unwoven fibrous webs criss-crossing lines of binderreeniorcement, as hereinbeiore described, it is possible to tie together substantially all of the fibers while at the same time limiting the bindertreated areas in the webs to only a small fraction of the total areas of the webs.

I claim:-

I. A web of carded fibers practically all of whose fibers are tied together by binder infused locally into the body of the web, the web area occupied by binder being only a small fraction of the tota area of the web.

2. A web of carded fibers substantially all of whose fibers lying in parallelism are tied together by binder infused into the body of the web along narrow lines running transversely of the fiber lay in said web, the web area occupied by binder being only a small fraction of the total area of the web.

3. A web of carded fibers substantially all of whose fibers lying in parallelism are tied together by binder infused into the body of the web along narrow lines running transversely of the fiber lay in said web and spaced apart a distance not exceeding the average fiber length of the fibers constituting the web, the web area occupied by binder being only a small fraction of the total area of the web.

4. A web of carded fibers substantially all of whose fibers are tied together by binder infused into the body of the web along narrow criss- -crossing lines spaced apart aadistance not exceeding the average fiber length of the fibers constitutingthe web,'the web area occupied by binder being only a small fraction or the total area oiithe web.

5. A.web otcarded fibers substantially .11 of .whose fibers lying in parallelism are tied together .by binder. infused into the body of the web along narrow lines running transversely of the fiber layin said web, said lines further defining compressed web regions but saidregions occupying only a small fraction 01- the-total area of the web. 6. A web of carded cotton fibers or an average fiber length selected from a range upwards oi about one-half inch and substantially all of whose fibers lying in parallelism are tiedtogether by binder infused into the body of the web along the lines running transversely of the fiber lay in said web and spaced apart a distance not exceeding the selected'average fiber length, the web .area occupied by binder being only a small fraction of the total area of the web.

7. A multi-ply web of carded fibers wherein the carded fibers of one ply are disposed angularly to the carded fibers of the adjacent ply and substantially all of whose fibers lying in parallelism in each ply are tied together by binder infused into the body of each ply along narrow lines running transversely of the fiber lay in each ply, the web area occupied by binder being only a small fraction of the total area of the web.

8. A multi-ply web of carded fibers wherein the carded fibers of one ply are disposed substantially perpendicularly to the carded fibers of the adjacent ply and substantially all of whose fibers are tied together'by binder infused into the bodies of both plies along narrow criss-crossing lines spaced apart a distance not exceeding the average fiben length of the fibers constituting the web, the web area occupied by binder being only a small fraction of the total area of the web.

9. A web of unwoven fibers of an average fiber length greater than about A and substantially all of whose fibers are tied'together by binder occurring locally in the body of the web, the web area occupied-by binder being only a. small fraction of the total area of the web.

10. A web of unwoven but entangled fibers of an average fiber length selected from a range upwards of about /2" and substantially all of whose fibers are tied together by binder occurring in the body of the web along criss-crossing lines spaced apart a distance not exceeding the selected average fiber length, the web area occupied by binder being only a small fraction of the total area of the web.

JOSHUA H. GOLDMAN.

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