Surgical sponge material

A nonwoven hospital sponge material has been provided comprising a layered fabric having an inner core of a substantially hydrophilic material disposed adjacent at least one outer or surface layer or between a pair of outer layers of a substantially hydrophobic material, said sponge material being bonded by passing the material through rolls engraved in a pattern of lands and grooves in such a way that a repeating pattern of three degrees of compression are imposed therein: high compression, intermediate compression and, little or no compression. A nonwoven fabric bonded in this manner becomes more absorbent, loftier, has good surface integrity and does not adhere to the wound surface, when the nonwoven sponge material is then compacted subsequent to the bonding step. This thusly constructed, rather lighweight nonwoven material, produces a relatively inexpensive and disposable hospital sponge and dressing material having all of the desirable features of the more expensive woven materials commonly used today.

BACKGROUND OF THE INVENTION 
This invention is concerned with surgical sponges and dressings and more 
specifically to an inexpensive disposable primary dressing for use in a 
hospital that most nearly approaches the advantageous characteristics of 
the more expensive dressing materials. 
Conventional wound dressings in the form of sponges and the like can 
generally be divided into four major types or categories. 
Plain gauze dressings are generally transfer types of dressings used either 
directly on a wound or indirectly over a non-adherent dressing. The 
primary function of this type dressing is to lift and transfer the blood 
and other exudates from the wound into a fluid holding reservoir, such as 
an abdominal pad. 
Washed gauze dressings are used where a softer, more open mesh, bulkier 
sponge might be needed for transfer. Such dressings have been made to 
provide a sponge structure that when applied, supplies some gentle 
pressure and cushioning than unwashed gauze sponges, however, inherently 
the structure is not uniform in thickness and several plies have to be 
utilized to provide optimal pressure. 
Another type of dressing in use today is a filled gauze sponge, which 
consists of one or two plies of unwashed gauze, an inner matrix of cotton 
or rayon fibers, and in some cases a layer of creped cellulose wadding 
used as an inner carrier. This type of dressing can be utilized as a small 
fluid reservoir for soaking up and holding limited amounts of exudate. It 
lacks the softness and bulk, and the ability to transfer exudates in the 
same amounts that can be achieved with washed gauze. 
Finally, another type of sponge or dressing being used today is similar to 
the filled gauze sponge with the only difference being the replacement of 
the gauze cover with a nonwoven material. Dressings of this type have 
characteristics similar to filled gauze sponges, but have additional 
deficiencies, for example, the structure has decreased strength when wet 
as compared to gauze, and the existence of a chemical binder in nonwoven 
material can be potentially irritating to some patients. Also, some of 
this type sponge or dressing have an apertured nonwoven cover that not 
only adheres to the wound, but because the apertures are larger than the 
granulating tissue it covers, then this tissue tends to grow through the 
apertures and retards healing. This type dressing has the further problem 
that its transfer characteristics are poor due to the cellulose wadding 
filler. 
A disposable surgical dressing is yet to be produced inexpensively that is 
absorbent, but has good fluid transfer properties; will not adhere to the 
wound; and, has good surface integrity so as to remain as "lint free" as 
possible. 
Accordingly, it is an object of the present invention to provide an 
inexpensive disposable primary dressing for hospital use that has all of 
the advantages of the more expensive counterparts without their inherent 
disadvantages. 
It is another object of this invention to produce a nonwoven dressing 
material that has high fabric volume per unit of weight, good imbibition 
of liquids and good surface integrity. 
It is still another object of this invention to achieve the above-described 
characteristics in a nonwoven material by bulking a layered, thermally 
bonded material. 
SUMMARY OF THE INVENTION 
A nonwoven surgical dressing material includes an inner core of a 
substantially hydrophilic fibers or blends of fibers having a 
substantially hydrophilic property characterizing same, said inner core 
being disposed adjacent to or sandwiched between outer or surface layer(s) 
of substantially hydrophobic fibers or blends of fibers having a 
substantially hydrophobic property characterising same. The thusly 
structured material may be bonded by passing the material through heated 
rolls engraved in a pattern of lands and grooves in such a way that 
imparts a repeating pattern thereon of three degrees of compression: high 
compression, intermediate compression and little or no compression. This 
bonded fabric is then compacted, thereby becoming bulkier, softer and more 
absorbent. Owing to the substantially hydrophobic nature of the outer 
layers of the dressing, it is also non-adherent and has good surface 
integrity--yet, with all these advantages, the product is relatively 
inexpensive to manufacture.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A unitary nonwoven fabric composed of layers of fibers is bonded together 
with heat and pressure, and is subsequently bulked or compacted to produce 
a fabric having high fabric volume per unit weight, having good imbibition 
of liquids, non-adherent characteristics, and has good surface integrity, 
as well as having improved absorbent capacity and fluid transfer rates 
from the outer layers to the inner core, and on to a secondary dressing. 
Referring to the drawings, FIG. 1 shows such a layered fabric wherein an 
inner layer of substantially hydrophilic textile-length fibers 11 has at 
least one outer layer 12 of substantially hydrophobic textile-length 
fibers in bonded contact therewith. The layers are bonded together with 
heat and pressure by passing the array between a pair of rolls which are 
both engraved in a pattern of lands and grooves which forms a series or 
pattern of pressure areas of various degrees. In general, the overall 
character of the fiber-displacement pattern caused by the bonding can be 
shown in FIG. 2 wherein three bonding areas are disclosed: a highly 
compacted area 22 where a land on one roller has traversed a land on 
another roll; an intermediately compressed area 23 formed where a land on 
one roll has traversed a groove on the other roll; and, a substantially 
uncompacted area 24 where a groove on one roll has traversed a groove on 
the other roll. There are approximately 25% highly compacted areas, 25% 
uncompacted areas and 50% intermediately compacted areas in any modular 
position of the bonded fabric, and the areas are in the form of 
quadrilaterals with parallel but do not necessarily have equal sides, 
herein given the term rhomboidal. Such a bonding process is outlined and 
described in U.S. Pat. No. 3,542,634, of common assignee. 
While FIG. 1 shows an inner layer of substantially hydrophilic fibers 
sandwiched between a pair of outer layers of substantially hydrophobic 
fibers, it should be understood that a single outer surface can be 
successfully used herein. Further, such a construction could be folded 
over on itself forming essentially the same fabric as shown in FIG. 1. 
Thus, we are actually disclosing a nonwoven fabric having an inner layer 
of substantially hydrophilic textile-length fibers, and at least one outer 
or surface layer of substantially hydrophobic textile-length fibers. 
FIG. 3 is a sectional view of the bonded fabric of FIG. 2 wherein the high 
compacted areas 32 have nearly no open or porous areas therein due to the 
high compaction and fusion of fibers therein. The substantially 
uncompacted areas 34 can be seen to be relatively porous and open due to 
the lack of compaction (groove to groove traverse) therein. 
The thusly bonded fabric is then compacted or bulked by treating, for 
example, with apparatus such as is described in U.S. Pat. No. 3,260,778, 
or the like. Micro-pleats or the like can be imparted to a fabric by 
squeezing or compacting same, which compaction causes the fabric to become 
rearranged into a repeating series of wave-like undulations substantially 
throughout its length and running across the width of the fabric. 
Upon compaction or bulking, the rhomboidal areas of varying compression 
become more open and porous due to the fiber rearrangement and 
displacement taking place therein. This would be especially true of the 
intermediately compressed and the uncompressed areas, which comprise 
approximately 75% of the area of the fabric. The stresses produced in a 
compaction process have a greater rearranging effect on these areas. This 
characteristic is what makes it possible for the fabric to be bulked 
without seriously breaking the major bonds holding the fabric together. 
The absorbent capacity of the thusly treated fabric is increased nearly 
two fold. Furthermore, due to increased surface area, wicking and fluid 
transfer rates are also advantageously increased. 
FIG. 4 shows a fabric 40 that has been bonded and compacted as described 
herein, wherein wave-like undulations, such as 41, are imparted into the 
fabric. Slightly lesser undulations or micro-pleats 42 are also 
interspersed generally throughout the fabric. It has been found that these 
undulations 41 and 42 are able to open up the interfiber relationships 
therein without seriously breaking the major bonds holding the fabric 
together. FIG. 5 further shows this especially when compared to FIG. 3. In 
FIG. 5, the highly compacted or bonded areas 52 can be seen to be somewhat 
more porous and open than before the compacting step was performed; while 
the intermediately compacted areas (not shown) and the substantially 
uncompacted areas 54 are much more open and porous, thereby permitting the 
fabric to be substantially more absorbent and have more loft than its 
untreated counterpart, while still maintaining the major fabric bonding 
mechanism. 
A primary dressing for hospital use can be made from this material that has 
all of the advantages of the more expensive counterparts without their 
inherent disadvantages. For example, using polyester fibers with a 
hydrophilic finish (such as 1.5 denier, 11/2" Eastman Type 41D) in the 
outer layers sandwiched around, for example, a predominately rayon inner 
core layer produces a surgical dressing having the following qualities or 
attributes important to such a dressing: excellent nonadherence 
characteristics; absorbent qualities found in the more expensive 
conventional dressings; and, surface integrity, or the lint-free 
characteristic, is improved significantly. 
The following examples are illustrative of the fabrics of this invention: 
EXAMPLE I 
An array of fiber layers comprising a pair of outer or surface layers of 
100% 1.5 denier, approximately 11/2" polyester fibers, each being 
approximately 20% of the total fabric weight (gms/sq. yd.), sandwiched 
around blended inner core layer of 85% 1.5 denier 1 9/16" rayon fibers and 
15% 3.0 denier, 11/2" polyester binder fibers, said inner layer being 
approximately 50% of the total fabric weight and being bonded with heat 
and pressure generally as outlined in U.S. Pat. No. 3,542,634. The 
repeating pattern of the variously compacted rhomboidal areas is thereby 
formed thereon. 
This thusly layered fabric is then treated with a compactor, such as is 
described in U.S. Pat. No. 3,260,778 or the like, so as to impart a 
repeating series of wave-like undulations substantially throughout its 
length and width and to cause portions of the highly compacted areas, the 
intermediately compacted areas and the substantially uncompacted areas to 
become more open and porous than before said treatment. 
The resulting fabric weighs approximately 37.6 gms/sq. yd., has a thickness 
of 26.0 mils (as measured by the Ames-Mercer gauge), a bulk of 14.7 
cm.sup.3 /gm. and an absorbent capacity of approximately 1100%. These 
figures compare favorably with those of the same fabric prior to being 
compacted: 34 gm/sq. yd., a thickness of 12.5 mils, a bulk of 7.85 cm 3/g 
and an absorbent capacity of 640%. 
EXAMPLE II 
An array of fiber layers comprising a pair of outer or surface layers of 
80% 1.8 denier 11/2" polypropylene fibers and 20% 3.0 denier polyolefin 
binder fibers sandwiched around an inner core layer of 75% of bleached 
comber cotton and 25% of the 3.0 denier polyolefin binder fiber. The 
fabric is bonded and compacted as described in Example I. 
The resulting nonwoven fabric was a soft, absorbent material having good 
surface integrity and similarly favorable improvements in bulk, thickness 
and absorbency as described above in Example I. 
EXAMPLE III 
Another method of making a nonwoven fabric for use as a primary surgical 
dressing, or the like, is to make a two-layered structure in the same 
manner as described above, wherein the first layer is approximately 6 
grams/sq. yd. of 11/2" 1.5 denier polyester fibers and a second layer of 
approximately 24 grams/sq. yd. composed of 80% 1 9/16" 1.5 denier rayon 
fibers and 20% 11/2" 3.0 denier polyester binder fibers. This two-layered 
structure is bonded with heat and pressure between the engraved rolls 
described in Example I. The fabric is then compacted as described earlier 
in Example I. This bonded and compacted fabric is then folded over on 
itself in a manner such that the rayon layer becomes the inner layer 
sandwiched between the polyester outer layers. 
This resulting nonwoven primary dressing material will have as improved an 
absorbent capacity as the 3-ply structure. The fabric has the desired 
nonadherence characteristics and the absorbent qualities of conventional 
dressings, while the surface lint present thereon has been significantly 
reduced. 
As can be observed above, the absorbent capacity of the fabrics have been 
significantly and unexpectedly increased due to the compacting step. 
Whereas the fabrics, such as outlined above, have an absorbent capacity 
before compacting of about six times its own weight, the same fabrics 
increase their absorbent capacity to more than eleven times their own 
weight after compaction, while still maintaining a good fiber bond 
therein. 
Substantially hydrophobic and thermoplastic outer layers and substantially 
hydrophilic inner layers used in this invention unexpectedly provides the 
fabrics produced herein with a combination of useful properties, as 
compared to the products shown in the examples of U.S. Pat. No. 3,542,634. 
For instance, Example I of U.S. Pat. No. 3,542,634 has surfaces of all 
cotton as opposed to the substantially hydrophobic surface used herein, 
and even though the patent states that fabrics described therein are "lint 
free" it is urged that the fabrics described in this invention, having 
substantially thermoplastic and hydrophobic surfaces is much more lint 
free than one with a cotton surface, partially due to fusion of the 
thermoplastic fibers used herein. Cellulosic fibers form only weak self 
bonds with adjacent cellulosic fibers in a heat and pressure bonding 
process, such as is used herein, and these bonds are usually destroyed by 
aqueous liquids. Additionally, cellulosic fibers are somewhat brittle and 
the carding action used to produce nonwoven webs tends to break some 
fibers and results in the undesirable presence of short fiber lint or 
dust. However, thermoplastic fibers are more resilient, by their nature, 
and are less prone to breakage. Furthermore, thermoplastic fibers will 
form bonds with adjacent fibers in such a heat and pressure bonding 
operation as is used herein, and these bonds are not destroyed by aqueous 
liquids, thereby increasing the surface integrity of the fabric. 
In order to more accurately describe this invention, the hydrophobic 
property of the outer or surface layer should have a rather high degree of 
hydrophobicity. The degree of hydrophobicity is commonly reported as the 
percent moisture regain for fibers, at 70.degree. F. and 65% relative 
humidity. For the purposes of this invention, the fibers used in the 
hydrophobic layers, should have a moisture regain of less than 5%. 
The outer surface of substantially thermoplastic fibers and inner layer of 
substantially hydrophilic fibers also has the additional features of good 
absorbency with the correspondingly desirable feature of nonadherence. 
These features are especially good properties for a primary hospital 
dressing. Having the hydrophobic surface in close contact with the wound 
permits the ready transfer of body fluids into secondary dressings, but it 
will not adhere to the wound itself. The hydrophobic surface will only 
transfer body fluids but will not retain moisture while the hydrophilic 
layer or surface will collect that body fluid and will also transfer the 
fluid into an adjacent secondary dressing. 
Of course, in addition to the use of this fabric as a primary dressing or 
surgical sponge material, it is urged that the material could also be 
advantageously used as dressing substrate for finger bandages, or the 
like. 
Since it is obvious that many modifications and embodiments can be made in 
the above-described invention without changing the spirit and scope of the 
invention, it is intended that this invention not be limited by anything 
other than the appended claims.