US3683921A

US3683921A - Absorbent sponges

Info

Publication number: US3683921A
Authority: US
Inventors: Berry A Brooks; Norman R Eisdorfer
Original assignee: BERRY A BROOKS; NORMAN R EISDORFER
Current assignee: BERRY A BROOKS; NORMAN R EISDORFER
Priority date: 1970-08-17
Filing date: 1970-08-17
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15
Also published as: NL7111337A; FR2102312B1; ZA715487B; FR2102312A1; GB1367959A

Abstract

A bonded, self-sustaining, single-use, disposable absorbent product having excellent softness and excellent strength, bulk, resilience and resistance to surface abrasion and linting, particularly when wet, comprising a plurality of layers of reinforced nonwoven textile fabrics, each of said layers comprising a synthetic polymeric thermoplastic reinforcing reticulate grid netting covered on each side by at least one layer of overlapping, intersecting fibers mechanically intertwined around and bonded to the individual elements of said grid netting, said plurality of layers of reinforced nonwoven textile fabrics being secured together at their peripheral edges to form a bonded, self-sustaining, single-use, disposable absorbent product, having excellent softness and excellent strength, bulk, resilience and resistance to surface abrasion and linting particularly when wet.

Description

United States Patent Brooks et al.

[54] ABSORBENT SPONGES [72] Inventors: Berry A. Brooks, 284 English Court, Somerville, NJ. 08876; Norman R. Eisdorfer, 14 Colburn Rd., East Brunswick, NJ. 08816 [22] Filed: Aug. 17, 1970 [21] Appl. No: 64,455

[52] US. Cl. ..128/296, 128/156, 161/160 [51] Int. Cl. ..A61f 13/00 [58] Field of Search ..l28/l32, 156, 290, 296; 161/160-161 [56] References Cited UNITED STATES PATENTS 2,705,692 4/1955 Petterson 128/290 W 2,833,283 5/1958 Spahr et a1 ..128/290 W 2,902,037 9/1959 Harwood et al ..128/290 W 2,986,780 6/1961 Bletzinger ..128/290 W 3,047,444 7/1962 l-larwood ..128/290 W 3,063,454 11/1962 Coates et a1. ..l28/290 W 3,482,567 12/1969 Franklin ..128/132 D [151 3,683,921 [451 Aug. 15,1972

Atzorney--Alexander T. Kardos and Robert L. Minier [5 7] ABSTRACT A bonded, self-sustaining, single-use, disposable absorbent product having excellent softness and excellent strength, bulk, resilience and resistance to surface abrasion and linting, particularly when wet, comprising a plurality of layers of reinforced nonwoven textile fabrics, each of said layers comprising a synthetic polymeric thermoplastic reinforcing reticulate grid netting covered on each side by at least one layer of overlapping, intersecting fibers mechanically intertwined around and bonded to the individual elements of said grid netting, said plurality of layers of reinforced nonwoven textile fabrics being secured together at their peripheral edges to form a bonded, self-sustaining, single-use, disposable absorbent product, having excellent softness and excellent strength, bulk, resilience and resistance to surface abrasion and linting particularly when wet.

5 Claims, 9 Drawing Figures Patented Aug. 15, 1972 3,683,921

4 Sheets-Sheet 75 ATTORNEY Patented Aug. 15, 1972 3,683,921

4 Sheets-Sheet 4 ABSORBENT SPONGES Thepresent invention relates to absorbent products for absorbing and retaining body fluids, blood, and other body exudates. More particularly, the present invention relates to absorbent products, such as surgical are equally applicable to other absorbent products wherein the properties of softness, strength, bulk, resilience, and resistance to surface abrasion and linting, particularly when wet, are of interest. Such other absorbent products include, for example, general use sponges and pads, diapers, surgical dressings, postoperative dressings, underpads, combine pads, compresses, and the like.

A laparotomy is a medical or surgical procedure or operation involving an incision through any part of the abdominal wall into the abdominal cavity. During such a medical procedure, and in many other medical procedures and operations, such as open heart, thoracic, GYN, etc., laparotomy sponges are used to absorb relatively large amounts of body fluids, blood, and other body exudates. Such laparotomy sponges are also used to Wall off organs, cover the outer edges of the incision, handle organs, pack off areas in the inci sion opening so that itis easier to gain access to other organs in the cavityopening, etc.

At the present time, sponges made of cotton gauze are customarily used to carry out such functions. Such cotton gauze sponges are usually made from 4 plies of USP. 28 X 24 mesh cotton gauze and usually come in sizes of 12 inches X 12 inches square, 18 inches X 18 inches square, 18 inches X 4 inches oblong, 36 inches X 8 inches oblong, etc.

Such cotton gauze sponges, however, are subject to many disadvantages. For example, they have a relatively high initial cost and have relatively high subsequent I labor costs due to their re-usable nature requiring laundering and sterilization after each use, hand removal of pills or neps from the surface to prevent them from falling off during an operation, repairing, resewing, hand-folding, etc. Also, the danger of infection and cross-contamination is a very serious consideration.

Additionally, the used sponges, even though thoroughly washed and sterilized, are usually spotted with blood or other stains from previous medical or surgical procedures or operations and thereby present a very unsightly and somewhat repulsive appearance. The esthetic and psychological effect of such a stained or spotted sponge is not very pleasing.

It is therefore very desirable that an economical, sin gle-use, disposable sponge or pad be developed and used to avoid the above-mentioned disadvantages. It is also very necessary that such a sponge or pad be soft and that it possess excellent strength, bulk, resilience, and resistance to surface abrasion and linting, particularly when wet.

It has been discovered that such a single-use, disposable sponge or'pad may be made by forming a synthetic polymeric thermoplastic reinforcing grid netting defining a pattern of open areas, placing at least one layer of absorbent fibrous materials on each side of the grid netting, adhering the layer of fibrous materials to the grid netting, then forming a laminate of a plurality of layers of such grid netting and fibrous materials adhered thereto, and securing the plurality of layers together at their peripheral edges, and internally of such edges, if so desired.

The inventive concept will be described in greater specificity by reference to the accompanying drawings and following specification wherein there is illustrated and described preferred apparatus and methods for producing the novel products of the present invention. It must be understood, however, that the inventive concept is not to be considered limited to the constructions shown except as determined by the scope of the ap pended claims.

In the drawings:

FIG. 1 is a simplified, schematic, perspective, exploded view of a reinforced nonwoven textile fabric composed of a plurality of fibrous webs and a centrally located reinforcing reticulate grid netting, prior to assembling and processing in accordance with the principles of the present invention;

FIG. 2 is a fragmentary, perspective view of a preferred embodiment of the reinforcing reticulate grid netting of FIG. I;

FIG. 3 is a simplified, schematic drawing of a preferred embodiment of apparatus and a method suitable for utilizing the principles of the present invention for making the reinforced nonwoven textile fabric such as shown in FIG. 1;

FIG. 4 is a simplified, schematic drawing of a preferred embodiment of apparatus and a method suitable for utilizing the principles of the present invention for assembling a plurality of reinforced nonwoven textile fabrics such as shown in FIG. 1;

FIG. Sis a simplified, schematic drawing of another preferred embodiment of apparatus and a method for utilizing the principles of the present invention for assembling a plurality of reinforced nonwoven textile fabrics such as shown in FIG. 1;

FIG. 6 is a simplified plan view of a laparotomy sponge as prepared by utilizing the principles of the present invention;

FIG. 7 is a partially exploded, magnified cross-sectional view of the laparotomy sponge of FIG. 6, taken on the line 7 7 thereof, in the direction indicated by the arrows.

FIG. 8 is a simplified plan view of another laparotomy sponge as prepared by utilizing the principles of the present invention;

FIG. 9 is a partially exploded, magnified, cross-sectional view of the laparotomy sponge of FIG. 8, taken on the line 9-9 thereof, in the direction indicated by the arrows.

With reference to the drawings and with particular reference to FIG. 1 thereof, there is shown a reinforced nonwoven textile fabric 10 comprising an outer layer- 12 of fibrous material, a centrally or internally disposed reinforcing reticulate plastic grid netting l4, and another outer layer 18 of fibrous material.

THE FIBROUS LAYER Each outer layer 12 and 18 may comprise merely a single fibrous web or may comprise a number of laminated fibrous webs which are brought together, usually to create a heavier weight layer.

The fibers which are employed to make up the layers 12 and 18 are highly absorbent and are preferably of a cellulosic nature, such as cotton or rayon. However, other fibers, either synthetic, man-made, or natural, may be used in various proportions for special purposes or for special effects. Illustrative of such other fibers are the polyamides (nylon 6/6, nylon 6, nylon 610, nylon l 1, etc.), acrylic fibers (Acrilan, Creslan, Orlon, etc.), modacrylic fibers (Dynel, Verel, etc.), polyester fibers (Dacron, Kodel, etc.), polyolefinic fibers (polyethylene, polypropylene, etc.), cellulose ester fibers (cellulose acetate, cellulose triacetate, etc.

It is not essential that the fibrous layers 12, 18 placed on each side of the plastic grid netting 14 be composed of the same type of fiber or the same denier or even that one layer be made of only one type of fiber or that both layers have the same weight. Blends and mixtures of the above referred to fibers are, of course, possible in substantially any range of proportions or weights, as desired or required.

It is preferred that the fibers be of textile staple length or equivalent length, or at least be cardable, that is to say, they should be from about one-half inch in average length up to about 3 inches or more in average length. Shorter fibers, down to about three-sixteenths inch or less in average length may be added in various proportions to comprise up to about 50 percent by weight of the web, or may comprise the entire web, particularly where the original method of web formation involved a fluid deposition of fibers, such as in a conventional or modified aqueous papermaking process, or in air deposition techniques In such fluid deposition processes, average fiber lengths of about three-six teenths inch or one-eighth inch are preferred to the extremely short fiber lengths of down to about one-sixteenth or one thirty-second inch and even below, such as used in conventional papermaking processes for making paper. Such very short fibers, such as these found in conventional papermaking processing, are of use, however, particularly for economic reasons or in those uses and applications wherein the tendencies toward paper-like properties and characteristics of paper and paper products are not objectionable.

The denier of the synthetic or man-made fibers used in forming the fibrous webs is preferably in the range of the approximate thickness of the natural fibers mentioned and consequently deniers in the range of from about 1 to about 3 are preferred. However, where greater opacity or greater covering power is desired, deniers of down to about three-fourths or even about onehalf may be employed. Where desired, deniers of up to l0, 15 or higher, may be used. The minimum and maximum denier are, of course, dictated by the desires or requirements for producing a particular fibrous web or nonwoven fabric, and by the machines and methods for producing the same.

The weight of the individual fibrous layer which is placed on each side of the reinforcing reticulate grid netting may be varied within relatively wide limits, depending upon the requirements of the finished product. A single, thin web of fibers, such as produced by a card,

may have a weight of from about 40 to about 200 grains per square yard. The minimum weight of one individual fibrous layer contemplated by the present invention is, however, about grains per square yard, usually ob tained from one card or by plying two card webs. The maximum weight for one individual fibrous layer may range upwards to about 600 or more grains per square yard depending upon the intended use of the final product. Within the more commercial aspects of the present invention, however, individual fibrous layer weights of from about grains per square yard to about 300 grains per square yard are contemplated.

These weights are measured prior to any shrinking of the fabric during subsequent processing and will increase accordingly subsequent to such shrinking.

The number of fibrous layers in the reinforced nonwoven fabric should, of course, be at least two, that is, one layer on each side of the plastic grid netting, in order to obtain the desired or required effects. Three, four, five or more layers, in any desired arrangement may be used with the plastic grid netting in the center or closer to one surface, as desired, where special effects are desired.

It is possible that a particular bonded reinforced nonwoven fabric may comprise more than one reinforcing reticulate plastic grid netting. For example, the reinforced nonwoven fabric may comprise three layers of fibrous webs as the two outermost layers and a central layer, with the two plastic grid nettings sandwiched in alternating fashion between the three layers of fibrous webs. Other arrangements and other configurations involving a plurality of plastic grid nettings and a plurality of fibrous webs are also possible depending upon the needs and requirements of the particular situation.

Also, if carded or fiber oriented webs are used as the fibrous webs, it is not essential that the predominant direction of fiber orientation be the same for all the card webs. If desired, the card webs may be cross-laid with their predominant direction of fiber orientation at right angles or other angles to each other, whereby various strength relationships are available.

it is, of course, possible to apply a fibrous layer to merely one side of the plastic grid netting and such would yield a fabric with different properties, characteristics, and appearance on each side. Such a fabric is of use where such differences can be tolerated.

THE GRID NETI'ING The reticulate grid netting 14 which is positioned between the fibrous layers 12 and 18 is a thermoplastic synthetic polymeric material, such'as polypropylene, polyethylene (low density 0.91-0.94, medium density 0.94, and high density 0.95-0.96 and above); polyamides especially nylon 66 (hexamethylene diamineadipic acid); nylon 610 (hexamethylene diaminesebacic acid) and nylon 6 (polycaprolactam); polyesters, especially polyethylene glycol terephtholate; polyacrylics or modacrylics; etc. These and other materials are of use provided they possess the necessary thermoplastic properties and other chemical and physical characteristics to the required degree and are capable of thermal or other activation as described herein.

High density polyethylene having a density generally greater than 0.94 grams per cubic centimeter, as well as predominantly isotactic polypropylene are of exceptional applicability to the principles of the present inventive concept.

As shown in FIG. 2, the reticulate grid netting 14 comprises intersecting rods or monofilaments 15 running in one direction and rods or monofilaments 15a running cross-wise to the rods or monofilaments 15. The intersecting rods or monofilaments l5 and 150 are preferably basically integral at their intersections l6 and define a regular pattern comprising a plurality of rectangular open areas 17 therebetween. Methods and apparatus for making such reticulate grid nettings are disclosed in greater detail in copending, commonly assigned patent applications Ser. No. 736,356, filed July 12, 1968; Ser. No. 799,438, filed Feb. 14, 1969; Ser. No. 857,989,filed Sept. 15, 1969.

The open areas 17 are preferably rectangular or square, as shown, but it is to be appreciated that other geometric shapes may be used. Such other shapes include diamonds, parallelograrns, rhomboids, polygons, etc., and are created by having the rods or monofilaments 15 and 15a intersect each other at acute or obtuse angles, other than the 90 angle shown.

The length of the sides of these geometric figures in the grid netting may vary relatively widely depending upon the needs and the requirements of the particular situation. Sides as small as about one-twelfth inch or about one-eighth inch are of use, although sides having a length of about one-fifth inch to about one-quarter inch are more commonly employed. Longer sides of up to about one-half inch or about three-quarter inch are utilizable, and even longer lengths are useful in special situations.

The grid netting is usually described in terms of its mesh size. For example, a 3 X 5 grid netting means that there are three monofilaments per inch in one direction and five monofilaments per inch in the other direction. Many other mesh sizes are of use. Such include: 4 X 9; 4X4;7X9;etc.

The physical nature and the chemical composition of the grid netting 14, however, must be such that it possesses a sufficient degree of potential therrnoplasticity and potential shrinkability at the time it is inserted between the layers of fibrous materials.

Another important feature of the grid netting 14 is more grains per square yard are found satisfactory. Within the more commercial aspects of the present invention, however, a range of from about grains per' square yard to about 80 grains per square yard is deemed desirable.

The physical nature and the chemical composition of the grid netting 14, however, is such that it possesses a sufficient degree of potential residual shrinkage at the time it is inserted between the layers of fibrous materials. Potential shrinkages of only about 3 percent are of use in the application of the present invention but larger potential shrinkages are preferred in the range of from about 5 percent to about 1.0 percent or l5 percent. Larger potential shrinkages up to 20 percent or 25 percent or even larger are useful in special applications.

The degree of residual or potential shrinkage which exists in the grid netting is controlled to a large extent by the particular processing and manufacturing techniques used in the original formation and pre-treatment of the grid netting itself. This is a very important factor. For example, the greater the degree of elongation, stretching, and drawing of the polymeric material during its original manufacture and the resulting greater degree of molecular orientation created in the polymeric material, then the greater is the tendency of the polymeric material to return or shrink in the the fact that the thicknesses of the intersections of the filaments l5 and 15a can be made the same as the thicknesses of the interstitial filaments between'the intersections whereby there are no high spots or low spots as is present in a conventionally woven gauze or scrim in which the intersections of the warp and filling are considerably thicker than the individual thicknesses of the interstitial warp and filling between the intersections. This flatness feature is, of course, a great advantage in the manufacture of the laparotomy sponge in that there is more intimate and more complete contact of all parts of the grid netting with the adjacent fibrous webs. Additionally, there is a complete absence of high spots or bumbs in the laparotomy sponge which is advantageous during its subsequent use in a medical or surgical procedure or operation.

The weight of the plastic grid netting may vary relatively widely depending upon the needs and requirements of the particular situation. Weights as low as about 15 grains per square yard up to about 150 or material to shrink is recognized in the art and such recognition leads to the second factor affecting the shrinkage characteristics of the polymeric material.

The second factor exists in the extent and in the duration of the annealing and relaxing treatment which is used to stabilize or heat-set the grid netting subsequent to its original formation. Use of extensive annealing or other heat-setting treatments such as normally used previously in theart with such products will generally tend to reduce'the tendency of the formed grid netting to shrink whereby its shrinkage capability substantially disappears. On the other hand, the use of less extensive annealing or heat stabilizing treatments or the complete ommission thereof will serve to maintain the tendency of the grid netting to shrink after formation whereby it is rendered suitable for the purpose of the present invention.

A third factor in the development of the shrinkage properties lies in the subsequent treatment of the laminated fabric'containing the grid netting having the residual or potential shrinkage characteristics. if such a laminated fabric is bonded and is then exposed to a heat treatment, such as a drying or resin-curing treatment at elevated temperatures and the grid netting is maintained in a tensioned condition, then the shrinkage characteristics are usually unable to assert themselves and substantially no shrinkage takes place. However, if the heat treatment takes place under controlled tension conditions, such as the passage of the laminated fabric over heated drying cans which rotate with controlled, predetermined progressively decreasing surface speeds, then the shrinkage'characteristics can be asserted and thegrid netting will shrink.

Such shrinkage properties and characteristics are of great advantage in controlling the thickness and bulk of the final product as well as the degree of rippling or puckering which can be imparted thereto. Such controlled rippling and puckering may be brought about at any desired time but preferably takes place during the heat sterilization of the absorbent product prior to use. As a result of such shrinking, rippling and puckering, the bulk or thickness is increased, and the softness and surface interest are enhanced.

The extent of the increase in bulk or thickness, softness and surface interest, etc., depends, of course, to a large extent upon the differential in shrinkage properties between the thermoplastic grid netting and the fibrous webs which are adhered thereto. Inasmuch as the peripheral edges of the thermoplastic grid netting and the fibrous webs are autogenously bonded together, and inasmuch as the thermoplastic grid netting shrinks to a far greater degree than the fibrous webs adhered thereto, the puckering and rippling in the central area bounded by the peripheral edges will be greater when the difference in shrinkage properties and characteristics is greater.

THE MANUFACTURE OF THE REINFORCED NONWOVEN FABRIC In FIG. 3, there is shown apreferred embodiment of a method and apparatus suitable for assembling an outer fibrous layer 22, a reinforcing reticulate plastic grid netting 24, and another outer fibrous layer 28 to form a reinforced nonwoven fabric Pressure-applying rotatable rolls 29, 30 and 31, 32 operate to press the various layers together into a laminated structure 33. This laminated structure 33 is then passed through a conventional fluid-rearranging apparatus 36 so as to rearrange the individual fibers thereof into a KEYBAK bundled non-woven textile fabric possessing a predetermined pattern of fabric openings and fiber bundles. Such apparatusis described ingreater detail in U. Pat. No. 2,862,251 which issued to Frank Kalwaites on Dec. 2, 1958 and reference thereto, particularly to FIGS. 7-10 thereof, is incorporated herein.

The rearrangement of the fibers during such a KEYBAK bundling process is particularly advantageous in that the individual fibers of the fibrous layers are rearranged and moved about sufiiciently so that they become mechanically intertwined and wrapped around the individual rods or filaments of the plastic grid netting. Such mechanical adherence of the fibrous layers to the grid netting is particularly advantageous in the case of those polymeric grid materials which are more difficult to adhesively bond to the fibrous layers.

The rearranged laminated structure 33' is then passed through conventional adhesive-applying or bonding apparatus 34 wherein a bonding agent is applied. The specific form of bonding method and apparatus is not critical and basically any well known form of rotatable print rolls which are suitably engraved or embossed as to pick up the proper amount of bonding agent from a trough or tank and deposit the same in the desired pattern on the laminated fabric is suitable.

Other forms of bonding, using other forms of coating and impregnating methods and apparatus, are also possible. Spraying, padding, dipping, and other forms of saturation or overall bonding are of value.

The binder used in adhering the plurality of webs and the grid netting together may be selected from a large group of such binders known to industry. It is necessary, however, that a binder be used which can satisfactorily adhere to and bond the different types of fibers together or at least mechanically interlock the fibers together. Representative of the binders available for such a purpose are: regenerated cellulose; vinyl resins such as plasticized or unplasticized polyvinyl acetate, polyvinyl chloride, polyvinyl alcohol, etc., either as homopolymers or copolymers; acrylic resins such as ethyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, etc.; butadiene resins such as butadiene-acrylonitrile, butadiene-styrene, etc.; other synthetic rubbers; natural rubber; urea resins such as urea-formaldehyde, cyclic urea-formaldehyde, etc.; aldehyde resins such as melamine-formaldehyde, phenolformaldehyde, resorcinol-formaldehyde, etc.; epoxy resins; cellulose derivatives such as carboxymethyl cellulose; hydroxyethyl cellulose, etc.; starches; gums; casein; etc.

These binders may be added, as desired, in the form of emulsions, solutions, dispersions, plastisols, powders, etc. Autogenic bonding preferably by heat and/or pressure and/or solvents, may also be used when thermoplastic fibers are present.

The percent add-on of such binder materials may be varied within relatively wide limits, depending to a large extent upon the specific binder employed and upon the type, weight and thickness of the fibrous web. For some binders, as low as about 1 percent by weight up to about 12 percent by weight, based on the weight of the dry webs being bonded, has been found satisfactory. For other binders, as high as from about 15 to about 50 percent by weight has been found preferable. Within the more commercial aspects of the present invention, however, from about 2 to about 35 percent by weight based on the weight of the dry webs being bonded has been found desirable.

The particular size, shape and configuration of the binder pattern used falls within the scope and range of binder areas previously used in the prior art. Examples of some of these binder patterns may be found in the abovementioned U. S. Pat. Nos. 2,705,687 and 2,705,688 or in U. S. Pat.'No. 2,880,111. Specific examples of binder areas, binder shapes and sizes, and interbinder spaces are noted in said patents.

The rearranged laminated structure 33" with the applied binder is then forwarded to a suitable heating device such as a heated oven 35 which is maintained at an elevated temperature in order to dry and, if necessary, cure the applied binder.

The temperature, pressure and duration of time of the heating, drying and curing are, of course, interdependent. Higher'temperatures permit the use of shorter exposure times, and lower temperatures require the use of longer exposure times. Temperatures in the range of from about 212 to about 325 F. are normally used with exposure times of from about 20 seconds to about 30 minutes.

The combined mechanical and adhesive bonding between the fibrous webs and the plastic grid netting thus forms a superior bond to that obtained by mechanical bonding alone or by adhesive bonding alone.

The bonded nonwoven fabric 10' is then forwarded to suitable wind-up rolls 37 to be used as supply rolls for the next procedure.

THE MANUFACTURE OF THE ABSORBENT PRODUCT under a heated cutting and heat-sealing platen 42 which reciprocates vertically, as shown, and serves to heat-seal the laminate 39 into a bonded, self-sustaining absorbent product.

The temperature, pressure, and duration of time of the heat-sealing are, of course, interdependent. Higher temperatures permit the use of shorter exposure times and lower pressures, and lower temperatures require the use of longer exposure times and higher pressures. Temperatures in the range of from about 225 to about 400 F. or 600 F., for periods of a part of a second, say 0.2 second, or a few seconds, say 1 or 2, up to or seconds, are possible. The pressures employed are generally in the range of from about 30 pounds per square inch (gauge) to about 100 pounds per square inch (gauge) and preferably from about 40 pounds per square inch to about 80 pounds per square inch (gauge).

As will be described in greater detail hereinafter, the heat sealing takes place along the peripheral edges of the laminate 39 as well as internally thereof, as desired or required. Pressure is exerted by the heated platen 42 which presses the laminate 39 against a stationary base or anvil 44. At the rearward or trailing edge of the platen 42 and anvil 44, a conventional cutting device (not shown) is used to cut the endless length of laminate 39 into shorter lengths 46 which are forwarded by conveying means such as a conveyor belt 48 to an assembly zone 50 where tapes or loops 52 are applied, as desired or required.

Although four reinforced nonwoven fabrics are used to illustrate the invention, it is to be appreciated that other combinations and other numbers of reinforced nonwoven fabrics may be used.

In FIG. 5, there is shown a variation of the method and apparatus illustrated in FIG. 4. In FIG. 5, supply rolls 57 forward four reinforced nonwoven fabrics through the nips of rotatable pressure-applying rolls 58, 60 to form a laminate 59. This laminate is then passed through the nip of heated rotatable sealing and cutting rolls 62 and 64 which serve to press together and heat the laminate at its peripheral edges and internally thereof, as desired or required. Conventional cutting means (not shown) are used to sever the endless lengths of the laminate 59 into short lengths 66 which are forwarded by conveying means such as a conveyor belt 68 to an assembly zone 70 where tapes of loops 72 are attached, as desired or required.

FIGS. 6 and 7 illustrate one typical form of bonding used to bond the laminate 39 at its peripheral edges 51 and internally thereof. FIG. 6 shows one manner of attaching the tapes or loops 52 to the main body of the laparotomy sponge.

FIGS. 8 and 9 illustrate another typical form of bond ing used to bond the laminate 59 at its peripheral edges 71 and internally thereof. FIG. 8 shows another manner of attaching the tapes or loops 72 to the main body of the laparotomy sponge.

It is to be appreciated that many other forms of bonding and bonding designs internally of the peripheral edges may be employed. For example, instead of using diagonals which form an X as in FIG. 8, lines parallel to the peripheral edges may be used to form a dividing the sponge into four substantially equal quadrants. Instead of using rectangles as in FIG. 6, other geometric figures may be used. Such other figures include squares, ellipses, ovals, circles, annuli, polygons, hexagons, etc.

The invention will be further described by reference to the following Examples wherein there are disclosed preferred embodiments of the present invention. However, it is to be appreciated that such Examples are illustrative and not limitative of the broader aspects of the inventive concept.

EXAMPLE I Four laparotomy sponges having dimensions of about 14 inches X 14 inches (after sterilization) are prepared to the following specifications:

1. Four plies of bonded rearranged KEYBAK nonwoven fabric comprising rayon fibers, 1% denier and l 9/ 16 inches staple length with each ply comprising two fibrous webs weighing about 172 grains per square yard to provide a total weight (four plies) of 1,376 grains per square yard. No reinforcement is used.

2. Four plies of reinforced bonded rearranged KEYBAK nonwoven fabric with each ply comprising a polypropylene reinforcing re'ticulate grid 3 X 5 netting weighing 45 grains per square yard covered on each side by a fibrous web of rayon fibers 1%. denier and 1 9/ 16 inches staple length, each web weighing 185 grains per square yard to provide a weight of 414 grains per square yard per ply or a total weight (four plies) of 1,656 grains per square yard.

(3) Four plies of reinforced bonded rearranged KEYBAK nonwoven fabric with each ply comprising a 6 X 4 rayon leno'weave weighing 71 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighing 185 grains to provide a weight of 440 grains per square yard per ply or a total weight of 1,760 grains per square yard.

(4) Four plies of reinforced bonded rearranged KEYBAK" nonwoven fabric with each ply comprising a 6 X 6 rayon leno weave weighing 106 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighing 185 grains per square yard to provide a weight of 476 grains per square yard per ply or a total weight of 1,904 grains per square yard.

All the fibrous webs are bonded with a formulated Rohmgg Haas HA-8, which is essentially a self crosslinkable ethyl acrylate copolymer binder. A wavy line print pattern is used with four 0.024 inch wide lines per inch. There are apertures formed per square inch during the fluid-rearranging process. The general procedures of FIG. 3 are followed, when applicable to the type of sample being made.

The four samples are formed into laparotomy sponges in accordance with the method illustrated in FIG. 4. They are sterilized to shrink and ripple to varying degrees of surface interest, softness, bulk and rippled effect as a result of such sterilization.

Sample 2 containing the thermoplastic grid netting bonds autogenously at its peripheral edges and internally thereof as illustrated in FIGS. 6 and 7. The thermoplastic grid netting softens and causes the bonding.

Samples

1, 3 and 4, not containing any thermoplastic grid netting do not bond autogenously and are stitched and sewn together at their peripheral edges and internally thereof.

Three samples of each are prepared; all three are evaluated and the average evaluation is shown below:

nonwoven nonwoven IIOI'IWOVCI'I nonwoven fabric fabric fabric fabric w/ grid w/ 6 X 4 w/ 6 X 6 control netting leno leno Grain weight per 344 414 440 476 sq. yd. per ply v Total grain weight 1376 1656 1760 1904 per 4 plies *Tensile Strength 18.6 21.3 29.4 28.6 M/D Dry (lbs.) *Tensile Strength 11.8 16.6 15.5 16.6 M/D Wet (lbs.) *Tensile Strength 0.9 7.9 5.9 10.2 C/D Dry (lbs.) *Tensile Strength 0.8 7.5 3.9 6.4 CID Wet (lbs.) Bulk (1 ply) lbs. 0.012 0.014 0.014 0.017 Bulk 4 ply) lbs. 0.038 0.053 0.049 0.057 Softness 4 X 4 10.2 16.2 34.5 31.5

*4-ply strips, l-inch width 1 Sample 1 (four plies of bonded nonwoven fabric without any reinforcement) is unsatisfactory. The cross tensile strengths are too low; and the wet and dry bulk and resilience are too low.

2. Sample 2 (4 plies of bonded nonwoven fabric with grid netting reinforcement) is satisfactory. Tensile strengths are excellent; wet and dry bulk and resilience are good; and softness is excellent. The puckered, rippled effect creates desirable softness, bulk, and surface interest.

3. Sample 3 (four plies of bonded nonwoven fabric with 6 X 4 leno weave reinforcement) is unsatisfactory. Softness is too low; wet and dry resilience are too low; and fabric is too harsh and has an unsatisfactory hand.

4. Sample 4 (four plies of bonded nonwoven fabric with 6 X 6 leno weave reinforcement) is unsatisfactory. Softness is too low; wet and dry resilience are too low; and fabric is too harsh and has an unsatisfactory hand.

EXAMPLE II The procedures of Example 1 are followed substantially as set forth therein with the exception that the HA-8 ethyl acrylate polymer binder is replaced with a viscose regenerated cellulose binder. All other conditions remain the same.

The test results are comparable to those obtained in Example I. Only the second sample (four plies of bonded nonwoven fabric with a grid netting reinforcement) is completely satisfactory.

EXAMPLE Ill The procedures of Example 1 are followed substan tially as set forth therein with the exception that the PIA-8 ethyl acrylate polymer binder is replaced by a Goodrich 2600Xl20 self cross-linkable. acrylic copolymer binder. All other conditions remain the same.

The test results are comparable to those obtained in Example 1. Only the second sample (four plies of bonded nonwoven fabric with a grid netting reinforcement) is completely satisfactory.

EXAMPLE IV The procedures of Example I are followed substantially as set forth therein with the exception that there are (a) apertures, (b) 225 apertures, and (c) 144 apertures formed per square inch rather than apertures during the fluid-rearranging process. The 144 and 225 apertured designs are square designs; that is, the apertures are aligned in rows in two directions in checkerboard fashion. The 95 and 165 apertured designs have the apertures staggered or nesting into each other in adjacent rows.

The test results are comparable to those obtained in Example I. Only the second sample (four plies of bonded nonwoven fabric with a grid netting reinforce ment) is completely satisfactory.

EXAMPLE V The procedures of Example I are followed substantially as set forth therein with the exception that in Sample 2, the 3 X 5 polypropylene reinforcing reticulate grid netting weighs: (a) 39 grains per square yard; (b) 47 grains per square yard; and (c) 55 grains per square yard rather than 45 grains per square yard.

The results are generally comparable to those obtained for Sample 2 in Example I, with the additional observation that autogenic bonding is easier and more effective with larger amounts of the thermoplastic polypropylene grid netting.

EXAMPLE VI The procedures of Example I are followed substantially as set forth therein with the exception that in Sample 2 the reinforcing reticulate grid netting is (a) predominantly 'isotactic polypropylene and (b) high density polyethylene having a density between 0.95 and 0.96 grams per cubic centimeter.

The results are generally comparable to those obtained for Sample 2 in Example 1. Both products are satisfactory for use as laparotomy sponges.

EXAMPLE VII Six laparotomy sponges are prepared to the following specifications:

1 Four plies of bonded rearranged KEYBAK nonwoven fabric comprising rayon fibers, 196 denier and 1 9/16 inches staple length; each ply comprising two fibrous webs weighing about 172 grains per square yard to provide a total weight (four plies) of 1,376 grains per square yard.

2 Four plies of reinforced bonded rearranged KEYBAK nonwoven fabric with each ply comprising a polypropylene reinforcing reticulate 3 X 5 grid netting weighing 45 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighing 185 grains per square yard to provide a weight of 4 1 4 grains per square yard per ply or a total weight (four plies) of 1,656 grains per square yard. i

3. Four plies of reinforced bonded rearranged KEYBAK" nonwoven fabric with each ply comprising a 6 X 4 rayon leno weave weighing 71 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighting 185 grains to provide a weight of 440 grains per square yard per ply or a total weight of 1,760 grains per square yard.

4. Four plies of reinforced bonded rearranged KEYBAK nonwoven fabric with each ply comprising a 6 X 6 rayon leno weave weighing. 106 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighting 185 grains to provide a weight of 476 grains per square yard per ply or a total weight of 1,904 grains per square yard.

5. Four plies of bonded MASSLINN nonwoven fabric which are not rearranged and not reinforced are made from rayon fibers 1% denier and 1 9/16 inches staple length; each ply comprises two fibrous webs each weighing about 172 grains per square yard to provide a total weight (four plies) of 1,376 grains per square yard.

6. Four plies of U.S.P-. 28 X 24 cotton mesh gauze.

All the fibrous webs are bonded with a formulated Rohm & Haas HA-8, which is essentially a self crosslinkable ethyl acrylate copolymer binder. A wavy line print pattern is used with four 0.024inch wide lines per inch. There are 165 apertures formed per square inch during the fluid-rearranging process. The general procedures of FIG. 3 are followed, when applicable to the type of sample being made.

The six samples are formed into laparotomy sponges in accordance with the method illustrated in FIG. 4. They are sterilized by heating. Only Sample 2 shrinks and puckers to a desirable surface interest and appearance, and possesses excellent bulk and a pleasing rippled effect as a result of such sterilization and the differential shrinking effect.

Sample 2 containing the thermoplastic grid netting bonds autogenously at its peripheral edges and internally thereof, as illustrated in FIGS. 6 and 7. Samples 1 and 3-6 which do not contain a thermoplastic grid netting do not bond autogenously and are stitched and sewn together.

36 inch X 36 inch squares are cut from each sample and are autoclaved at 250 F. for minutes. Each sample is then soaked in distilled water for thirty seconds and allowed to absorb 150ml. Excess water absorption is removed by squeezing. Each sample is then placed in a 1,000 ml. tall Pyrex beaker (4 inch internal diameter) in a randomlyballed manner. A plastic beaker (3% inch external diameter) is placed on top on the randomly balled sample and various weights are added, causing the sample to compress. The degree of compression is observed. All weights are then removed and the amount of spring-back or resilience is observed. The results are as follows:

63 l .5 1282.5 1941.5 Amount of grams grams grams spring-back Keybuk nonwoven 730 800 820 30 fabric Nonwoven fabric 390 600 670 with grid netting 450 630 700 I00 (3 samples) 450 650 700 I00 Nonwoven fabric 650 740 800 40 with 6 X 4 leno Nonwoven fabric 600 750 770 60 with 6 X 6 leno Masslinn nonwoven 670 760 820 i 50 fabric 28x24 cotton gauze 750 800 820 40 The larger the number, the greater is the compaction. Values of 800 and 820 reveal substantially no resistance to the application of compressive force. Such EXAMPLE Vllll The procedures of Example V11 are followed substantially as set forth therein with the exception that (0.9 percent) saline solution, containing sodium chloride in the proportion of nine to 1000, is substituted for the distilled water.

The results are comparable to those obtained in Example VII. Sample 2 containing the thermoplastic grid netting passes the wet bulk compression test and the resilience test. All other samples fail these tests.

EXAMPLE 1X Six laparotomy sponges are prepared to the following specifications:

1. Four plies of bonded rearranged KEYBAK" nonwoven fabric comprising rayon fibers, l k denier and 1 9/16 inches staple length; each ply comprising two fibrous webs weighing about 172 grains per square yard to provide a total weight (four plies) of 1,376 grains per square yard.

2. Four plies of reinforced bonded rearranged KEYBAK" nonwoven fabric; polypropylene reinforcing reticulate 3 X 5 grid netting weighing 45 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighing grains per square yard to provide a weight of 414 grains per square yard per ply or a total weight (four plies) of 1,656 grains per square yard.

3. Four plies of reinforced bonded rearranged KEYBAK nonwoven fabric; polypropylene reinforc- 15 ing reticulate 4 X 9 grid netting weighing 55 grains per square yard covered on each side by a fibrous web of rayon fibers 156 denier and 1 9/ 16 inches staple length, each web weighing 185 grains to provide a weight of 425 grains per square yard per'ply or a total weight (four plies) of 1,700 grains per square yard.

4. Four plies of reinforced nonwoven fabric; 6 X 4 rayon leno weave weighing 71 grains per square yard covered on each side by a fibrous web of rayon fibers 196 denier and 1 9/16 inches staple length, each web weighing 185 grains per square yard to provide a weight of 440 grains per square yard per ply or a total weight of 1,760 grains per square yard.

5. Four plies of reinforced bonded rearranged KEYBAK nonwoven fabric; 6 X 6 rayon leno weave weighing 106 grains per square yard covered on each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, each web weighing 185 grains to provide a weight of 476 grains per square yard per ply or a total weight of 1,904 grains per square yard.

6. Four plies of USP. 28 X 24 cotton gauze fabric.

The linting properties and characteristics of these samples are determined as follows: 10 samples of each sponge are steam sterilized at 250 F. for 30 minutes and then conditioned at 65 percent Relative Humidity and 70 F. for at least 4 hours. The samples are then weighed. The samples are then immersed and dipped five times in 1,000 ml. saline solutions in a 1,500 m1. beaker. The samples are squeezed once to remove all free running water which is returned to the 1,500 ml. beaker. The wet samples are then placed on a black filter paper on a Buchner funnel and the remainder of the collected 1,000 ml. saline solution filtered through the sample on the black filter paper. The samples are then washed with distilled water. The lint is then collected and weighed and averages for the ten samples are calculated. The results are as follows:

Linting 1. Keybak nonwoven fabric 0.016% 2. Nonwoven fabric with 3 X 5 0.005% grid netting (3 samples) 0.005%

3. Nonwoven fabric with 4 X 9 0.005% grid netting 4. Nonwoven fabric with 6 X 4 0.01 1% leno 5. Nonwoven fabric with 6 X 6 0.010% leno 6. 28 X 24 cotton gauze 0.01 1% Samples 2 and 3 containing the reinforcing thermoplastic grid netting pass the linting test and are considered satisfactory. Samples 1 and 4-6 do not pass the linting test described above and are considered relatively unsatisfactory.

EXAMPLE X A reinforced bonded rearranged KEYBAK nonwoven fabric is prepared by placing a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length weighing 750 grains per square yard on each side of a polypropylene reinforcing reticulate 4 X 9 grid netting weighing 100 grains per square yard. Rearrangement forms fabric openings and fiber bundles, whereby many individual fibers are intertwined and wrapped around the grid netting. Adhesive bonding with I-IA-8, a self cross-linkable ethyl acrylate copolymer, bonds the nonwoven fabric. Autogenic heat sealing at the peripheral edges and internally thereof is rendered more difficult due to the heavier weight of the fibrous webs. However, the heavier weight of the polypropylene grid netting helps in the autogenic bonding. The resulting product, however, is relatively stiff and has poor drape and hand. It is not soft. Upon sterilization, the reinforced nonwoven fabric shrinks as doall such fabrics but the instant fabric becomes stiff and boardy. It is not suitable for use as a surgical sponge or pad.

EXAMPLE XI Four samples as described in particularity in Example I are prepared and their bulk or thicknesses measured both before and after undergoing sterilization procedures in steam at 250 F. for 30 minutes. The results are as follows:

Thicknexs Percent Before After Change 1. Keybak" nonwoven fabric 0.009" 0.009" 0.0%

2. Keybak" nonwoven fabric 0.018" 0.020" +1 1.1%

with grid netting 0.020" 0.023" +l5.0%

(3 samples) 0.014" 0.018" +28.6%

3. Keybak nonwoven fabric 0.013" 0.014" +0.77% with 6 X 4 leno 4. Keybak" nonwoven fabric 0.017" 0.016" 0.59% with 6 X 6 leno Sample 2 shrinks as noted and creates a very desirable rippling and puckering effect, thus enhancing the surface interest of the product and increasing the softness and bulk thereof. These products are considered satisfactory for use as laparotomy sponges.

Samples

1, 3 and 4 do not shrink materially and remain relatively flat without any enhancement of the surface interest, softness or bulk. These products are not considered satisfactory for use as laparotomy sponges.

EXAMPLE XII A laparotomy sponge is formed of six plies of reinforced, bonded, rearranged KEYBAK nonwoven fabric, each ply comprising a central layer of polypropylene reinforcing reticulate grid 3 X 5 netting weighing 40 grains per square yard, covered bn each side by a fibrous web of rayon fibers 1% denier and 1 9/16 inches staple length, weighing grains, for a total weight (six plies) of 1,920 grains per square yard. The laparotomy sponge is found satisfactory in use.

EXAMPLE XIII l7 specific Examples, such is for the purpose of illustrating the invention and is not to be construed as limiting it, except as defined by the appended claims.

What is claimed is: 1. An improved sterilized surgical sponge comprising a plurality of layers of reinforced, non-woven, textile fibers; said layers each comprising a synthetic, polymeric thermoplastic reinforcing grid covered on each side by at least one layer of a non-woven textile fabric of overlapping, intersecting fibers mechanically intertwined around the individual elements of said grid; said grid having, prior to sterilization, a shrinkage potential of about 3 to about 25 percent; said plurality of reinforcedlayers being secured together continuously at their peripheral edges and intermittently interfrom about three-sixteenths inch and to about 3 inches.

3. The sponge of claim 1 wherein the weight of each individual fibrous layer ranges from about grains per square yard to about 600 grains per square yard.

4. The sponge of claim 1 wherein the plurality of layers are secured together by heat binding.

5. The sponge of claim 1 wherein the thermoplastic reinforced grid is made of polypropylene.

Claims

2. The sponge of claim 1 wherein the fibers of said non-woven textile fabric are of an average length of from about three-sixteenths inch and to about 3 inches.
3. The sponge of claim 1 wherein the weight of each individual fibrous layer ranges from about 100 grains per square yard to about 600 grains per square yard.
4. The sponge of claim 1 wherein the plurality of layers are secured together by heat binding.
5. The sponge of claim 1 wherein the thermoplastic reinforced grid is made of polypropylene.