CA2389473A1 - Slip-resistant and absorbent material - Google Patents

Abstract

A medical fabric having an absorbent fabric having a slip-resistant material applied to a surface of the absorbent fabric forming a slip-resistant surface.
The medical fabric has an absorbency, as measured through the slip-resistant surface, of at least half of the absorbency of the absorbent material. The slip-resistant surface has a coefficient of friction of at least about 0.3.

Description

SLIP-RESISTANT AND ABSORBENT MATERIAL
Field of the Invention The present invention relates to slip-resistant and absorbent materials, and more particularly to slip-resistant and absorbent materials useful in surgical drape applications.
Background of the Present Invention Drapes are used during surgical procedures to create and maintain a sterile environment about the surgical site. Draping fabrics and materials are selected to create and maintain an effective barrier that minimizes the passage of microorganisms between non-sterile and sterile areas. Biological contaminates may be carried by liquids such as blood, saliva, perspiration, and life support liquids such as plasma and saline. To be effective, a draping material should be resistant to these liquids and prevent such liquids from passing through the draping materials and contaminating the sterile field.
A variety of surgical drapes exist, but most share several common features.
Most drapes are made of a fluid-repellent or fluid-impermeable material, or are coated with such a material, to prevent the passage of bodily fluids as well as contaminating microorganisms. Many of today's surgical drapes are made of disposable nonwoven

2 0 fabrics, plastic films, or papers. Additionally, many surgical drapes include an opening or aperture (more commonly known in the medical field as a "fenestration") through which the surgical procedure is performed. It may also be desirable that the fabric that is disposed about the fenestration be sufficiently absorbent to manage fluids that are typically present in surgical procedures. Such reinforcement may also assist in maximizing aseptic conditions around the fenestration by not only absorbing the fluids present, but by preventing the fluids from passing through the surgical drape to the patient.
During surgical procedures, it is sometimes convenient for operating personnel to place surgical and other medical instruments on the drape which is disposed over the patient. These instruments are placed near the fenestration in the drape through which the procedure is being conducted. In such instances, the surgical drape area surrounding the fenestration may be reinforced against tearing or puncture. It may be desirable to have the drape area near the fenestration be sufficiently slip-resistant to minimize the unintentional movement of surgical or other medical instruments disposed thereupon.
These drape enhancements may compromise the absorbency of the draping material around the fenestration. For example, foam reinforcement materials have been utilized to

3 PCT/US00/30613 increase the slip-resistance of a draping system in the area proximate to the fenestration.
Unfortunately, the absorbency of the foam reinforcement material may not be adequate to assist in controlling fluids about the fenestration.
In surgical drapes made from polymeric fibers, especially those made from hydrophobic polymers such as polypropylene and polyethylene, the combination of fluid management and slip resistance attributes are not typically present. This is most likely due to several factors, including the inherently low coefficient of friction (COF) values of fiber-forming polymers, especially polypropylene and polyethylene. The low coefficient of friction may also be attributable to the various treatments that are added to the fibers, either internally or topically, to change the way the polymeric fibers interact with fluids, typically aqueous and or alcohol-based fluids, that are present in surgical procedures.
Prior to this invention, commercial disposable surgical drapes made from 100%
polymeric materials (containing no cellulose elements) have used reinforcement materials that provide either sufficient fluid management (absorbency) or sufficient anti-slip attributes, but not both. For example, polyurethane foams provide sufficient anti-slip properties, but do not provide sufficient absorbency in many applications.
Thus, there remains a need for a fabric suitable for use in surgical applications as a reinforcement material which possesses sufficient slip-resistance to minimize unintentional movement of surgical instruments placed on the fabric, while being 2 0 sufficiently absorbent to manage fluids which are typically present in surgical procedures.
In response to this need, the present invention is directed to a medical fabric that includes a slip-resistant material applied to an absorbent material in a manner that increases the frictional properties of the absorbent material to reduce instrument slippage without having a significant negative impact on the absorbent properties of the material.
Other objects, advantages and applications of the present invention will be made clear by the following detailed description.
Summary of the Present Invention The present invention relates to a medical fabric suitable for use in a variety of applications, including, but not limited to, surgical drapes and surgical drape fenestration materials. The medical fabric may be formed from many different types of absorbent fabrics, such as, for example, nonwoven or other types of fabrics. The absorbent fabric may be an absorbent laminate, such as a meltblown/spunbonded laminate material. The absorbent laminate may, in some embodiments, have a fluid impermeable film attached to the side of the laminate that does not have a slip-resistant material applied thereupon.

A slip-resistant material may be applied to a surface of the absorbent fabric by using any of a number of available processes, such as, for example, meltspraying, laminating, and the like. The slip-resistant material may be any of a variety of polymers, including, but not limited to, amorphous polyalphaolefins. Thus, a slip-resistant surface is formed on the medical fabric. In selected embodiments, the slip-resistant surface has a coefficient of friction of at least about 0.3. The coefficient of friction may be higher in some embodiments.
In some embodiments, the medical fabric of the present invention has an absorbency, as measured through the slip-resistant surface, of at least half the absorbency of the absorbent material. The medical fabric may have an absorbency in the range of at least 50% to 100% of the absorbent fabric, as measured through the slip-resistant surface. The absorbency may be measured by different tests.
When the slip-resistant surface is applied to the absorbent fabric, the percentage of area of the surface of the absorbent fabric that is covered by the slip-resistant material may vary considerably. In selected embodiments, the percentage of area of the slip resistant surface that is covered by the slip-resistant material may range from a negligible amount to greater than 90%.
The slip-resistant and absorbent fabric of the present invention may be formed by varying processes, including first providing an absorbent material having a first and 2 0 second surface. A meltspray of fibers of a slip-resistant material may be applied to the first surface of the absorbent material. The slip-resistant material is applied to the absorbent material so that the absorbency of the slip-resistant and absorbent material is at least half of the absorbency of the absorbent material. The slip-resistant and absorbent material is then packed so that the first surface containing the slip-resistant material is 2 5 adjacent to the second surface of another layer of the absorbent material.
Winding the slip-resistant and absorbent material onto a roll can do this. These adjacent layers may be easily separated from each other without sticking to the adjacent layer.
Detailed Description of the Present Invention 30 Reference will now be made in detail to certain embodiments of the invention. It should be appreciated that each example is provided to explain the invention, and not as a limitation of the invention. For example, features described with respect to one embodiment may be used with another embodiment to yield still a further embodiment.
Such modifications and variations are within the scope and spirit of the invention.

In response to the foregoing challenges that have been experienced by those of skill in the art, the present invention is directed to a fabric or material that has both slip-resistant and absorbent properties that make it suitable for use in surgical draping applications. Such a material may be suitable as use for a surgical drape, or may be suitable for use as a reinforcement material that may be applied to a surgical drape. The material of the present invention is formed in a manner that increases the frictional properties of the material to reduce instrument slippage without negatively impacting the absorbent properties of the material.
As used herein, the terms "nonwoven fabric" or "nonwoven web" refer to a fabric that has a structure of individual fibers or filaments which are randomly and/or unidirectionally interlaid in a mat-like fashion. Nonwoven fabrics can be made from a variety of processes including, but not limited to, airlaid processes, wetlaid processes, hydroentangling processes, staple fiber carding and bonding, and solution spinning.
Suitable nonwoven fabrics include, but are not limited to, spunbonded fabrics, meltblown fabrics, wetlaid fabrics, hydroentangled fabrics, spunlaced fabrics and combinations thereof.
As used herein, the term "meltspun fabric" refers to a nonwoven web of filaments or fibers, which are formed by extruding a molten thermoplastic material, or coextruding more than one molten thermoplastic material, as filaments or fibers from a plurality of fine, usually circular, capillaries in a spinnerette with the diameter of the extruded filaments or fibers. Meltspun fabrics include, but are not limited to, spunbonded fabrics and meltblown fabrics and are characterized as having thermal bonding junctions throughout the fabric.
As used herein, the term "spunbonded fabric" refers to a meltspun fabric having small diameter continuous filaments which are formed by extruding a molten 2 5 thermoplastic material, or coextruding more than one molten thermoplastic material, as filaments from a plurality of fine, usually circular, capillaries in a spinnerette with the diameter of the extruded filaments then being rapidly reduced, for example, by noneductive or eductive fluid-drawing or other well known spunbonding mechanisms.
These small diameter filaments are substantially uniform with respect to each other. The diameters that characterize these filaments range from about 7 to 45 microns, preferably from about 12 to 25 microns. The production of spunbonded nonwoven webs is illustrated in patents such as Appel et al., U.S. Pat. No. 4,340,563; Dorschner et al., U.S. Pat. No.
3,692,618; Kinney, U.S. Pat. Nos. 3,338,992 and 3,341,394; Levy, U.S. Pat: No.
3,276,944; Peterson, U.S. Pat. No. 3,502,538; Hartman, U.S. Pat. No.
3,502,763; Dobo et al., U.S. Pat. No. 3,542,615; and Harmon, Canadian Patent No. 803,714.

4 As used herein, the term "meltblown fabrics" refers to a meltspun fabric comprising fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into a high velocity gas (e.g.
air) stream which attenuates the filaments of molten thermoplastic material to reduce their diameters, which may be to "microfiber" diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers. The meltblown process is well known and is described in various patents and publications, including NRL Report 4364, "Manufacture of Super Fine Organic Fibers" by V. A. Wendt, E. L. Boone, and C. D. Fluharty;
NRL
Report 5265, "An Improved Device for the Formation of Super Fine Thermoplastic Fibers"
by K. D. Lawrence, R. T. Lukas, and J. A. Young; and U.S. Pat. No. 3,849,241 issued Nov. 19, 1974 to Buntin et al. As used herein, the term "melt spraying" refers to applying meltblown fibers to a surface of a material.
As used herein, the term "microfibers" means small diameter fibers having an average diameter not greater than about 100 microns, for example, having a diameter of from about 0.5 microns to about 50 microns. More specifically microfibers may also have an average diameter of from about 1 micron to about 20 microns. Microfibers having an average diameter of about 3 microns or less are commonly referred to as ultra-fine microfibers.
2 0 As used herein, the term "wetlaid fabrics" refers to fabrics formed by a process, such as a paper-making process, wherein fibers dispersed in a liquid medium are deposited onto a screen such that the liquid medium flows through the screen, leaving a fabric on the surface of the screen. Fiber bonding agents may be applied to the fibers in the liquid medium or after being deposited onto the screen, or may be thermally bonded 2 5 after removal from the screen. Wetlaid fabrics may contain natural and/or synthetic fibers.
As used herein, the term "hydroentangle" or "hydroentangling" refers to a process wherein a nonwoven web of material consisting of one or more types of fibers are subjected to high velocity water jets, which entangle the fibers to achieve mechanical bonding.
30 As used herein, the term "spunlaced fabrics" refers to a nonwoven web of material consisting of one or more types of noncontinuous fibers, where the fibers are hydroentangled to achieve mechanical bonding without binder materials or thermal bonding.
The present invention may be formed from many different types of absorbent 3 5 fabrics, such as, for example, nonwoven or other types of fabrics. The absorbent fabric

5 may be a laminate, such as a nonwoven laminate. Multilayer laminates may be utilized in the present invention wherein some of the layers are spunbond and some are meltblown such as a spunbond/meltblown/spunbond (SMS) laminate as disclosed in U.S. Pat.
No.
4,041,203 to Brock et al. and U.S. Pat. No. 5,169,706 to Collier, et al., or any of a variety of film/spunbond laminates such as an SFS (spunbond/film/spunbond) construction. An SMS laminate may be made by sequentially depositing onto a moving forming belt first a spunbond fabric layer, then a meltblown fabric layer and last another spunbond layer and then bonding the laminate in a manner described above. Alternatively, the fabric layers may be made individually, collected in rolls, and combined in a separate bonding step.
The fabric of this invention may also be laminated with staple fibers, paper, and other web materials. Multiple meltblown, spunbond, film or other layers may of course be used. Each nonwoven fabric layer within the laminate may also be formed from a plurality of separate nonwoven webs wherein the separate nonwoven webs may be similar to or different from one another. The layers within the laminate may be attached to each other using a variety of attachment methods, including, for example, point bonding and adhesive lamination.
Additionally, an absorbent material that may be useful in the present invention may include at least one hydrophilic meltspun fabric layer and a film attached to the meltspun fabric layer. The hydrophilic meltspun fabric may be provided as an outermost layer of the material of the present invention. Thus, this outer layer is helpful in absorbing fluids that 2 0 contact the outermost surface of the fabric. The material may include a hydrophilic spunbonded fabric layer, or a hydrophilic spunbonded fabric having a breathable film attached thereto. As used herein, the term "breathable" refers to a material allows the passage of vapor and/or gas therethrough, but forms a barrier against the passage of liquids. Breathable films are well known in the art and may be produced by any known 2 5 method.
Although the fibrous components of the meltspun fabric may be formed from hydrophobic polymeric materials, the meltspun fabric may be made hydrophilic by incorporating a hydrophilic chemical additive in or on the meltspun fibrous components of the fabric.
30 The hydrophilic meltspun fabric may be combined with at least one other layer that provides additional properties to the material. For example, the material of the present invention may include an outermost layer of a hydrophilic meltspun fabric, in the form of a spunbonded fabric, and an inner film layer which, when in use, may contact a patient.
The nonwoven fabrics useful in the present invention may also include 35 monocomponent and/or multi-component, or conjugate, synthetic filaments and/or fibers

6 that may be produced from a wide variety of thermoplastic polymers that are known to form fibers. Suitable polymers for forming the nonwoven fabrics include, but are not limited to, polyolefins (such as polyethylene and polypropylene), polyesters, polyamides, polyurethanes, and the like. Of the polymers that are suitable for forming conjugate fibers that are made from components that melt at different temperatures, particularly suitable polymers for one of the components of the conjugate fibers include polypropylene, copolymers of propylene and ethylene and blends thereof, polyesters, and polyamides, more particularly polypropylene. Particularly suitable polymers for one of the components include polyethylenes, and more particularly linear low density polyethylene, high density polyethylene and blends thereof. Most suitable component polymers for conjugate fibers are polyethylene and polypropylene. In such a conjugate fiber having two different components, the polymer components may be selected so that the resulting bicomponent filament is capable of developing a helical crimp.
In addition, the polymer components may contain thermoplastic elastomers blended therein or additives for enhancing the crimpability and/or lowering the bonding temperature of the fibers, and enhancing the abrasion resistance, strength and softness of the resulting webs. For example, the low melting polymer component may contain about 5 to about 20% by weight of a thermoplastic elastomer such as an ABA' block copolymer of styrene, ethylenebutylene and styrene. Such copolymers are commercially available and some of which are identified in U.S. Pat. No. 4,663,220 to Wisneski et al. An example of a highly suitable elastomeric block copolymer is KRATON 62740.
Another group of suitable polymer additives is ethylene alkyl acrylate copolymers, such as ethylene butyl acetate, ethylene methyl acrylate, and ethylene ethyl acrylate.
The suitable amount to produce desired properties is from about 2 wt. % to about 50 wt. %, based on 2 5 the total weight of one of the polymer components. Other suitable polymer additives include polybutylene copolymers and ethylenepropylene copolymers.
One fabric that is commonly utilized as a fenestration reinforcement fabric includes a polyurethane foam that is laminated to a liquid impervious film, and is referred to herein as "Type 1" fabric, web or material. Another fabric that is commonly utilized as a fenestration reinforcement material is described in U.S. Patent No. 4,379,192, the entirety of which is hereby incorporated by reference. This material is referred to herein as "Type 2" fabric, web or material, and includes an upper layer of a polypropylene spunbond (SB) material that is topically treated with a surfactant. A second layer, which is adjacent to the upper layer of spunbond material, is a polypropylene meltblown (MB) layer that is topically

7 treated with a surfactant. A lower layer of liquid impervious film is bonded to the second layer.
Yet another fenestration reinforcement fabric used in surgical drape applications includes an upper layer of a bicomponent spunbond (SB) that is internally treated with a surfactant, a center layer of polypropylene meltblown (MB) that is topically treated with a surfactant, and a lower layer of liquid impervious film that is bonded to the second layer.
This material is referred to herein as "Type 3" fabric, web or material. This material is more fully described in U.S. Patent No. 5,540,979 to Yahaoui et al., the entirety of which is hereby incorporated by reference. This fabric is utilized in the samples of the present invention and is currently available from Kimberly-Clark Corporation as Absorbent Fabric Reinforcement.
To increase the slip resistance of an absorbent material, a slip-resistant layer may be applied to a surface of the absorbent material. A wide variety of materials may be applied to an absorbent fabric, web or material to improve its slip resistance while maintaining its absorption characteristics. For example, ethylene vinyl acetate copolymers, styrene-butadiene, cellulose acetate butyrate, ethyl cellulose, synthetic rubbers including for example KratonT"" block copolymers, natural rubber, polyethylenes, polyamides, flexible polyolefins, and amorphous polyalphaolefins. These materials may also be applied to the absorbent material in a variety of ways, such as, for example, melt 2 0 spraying, slot coating and printing.
A quantitative comparison of the attributes of the currently available fenestration reinforcement fabrics and materials of the present invention may be shown by a variety of tests that provide quantitative measurements that are indicative of slip-resistance and absorbency.
2 5 To measure the slip-resistance of a material, a coefficient of friction (COF) test may be utilized. One such test is ASTM D1894, which tests the coefficient of friction of a material surface. The slip-resistant surface of the material is placed against a stainless steel plate to measure the propensity of a stainless steel instrument to slip with respect to the slip-resistant surface of the material. For the Type 2 and Type 3 samples, the upper 30 layer of spunbond was placed against the stainless steel plate. For Type 1 samples, the upper layer of foam was placed against the stainless steel plate. For the materials of the present invention, the surface of the material upon which the meltspray of adhesive has been applied is considered to be the slip-resistant surface of the material.
A sled, to which the test specimen has been mounted, is pulled over a stationary 35 stainless steel platen. As used herein, the term coefficient of friction (COF) is defined as

8 the relative difficulty encountered when the surface of one material slides over an adjoining surface of a stainless steel plate. A high coefficient of friction denotes low slip between the surfaces (high slip resistance), while a low coefficient of friction denotes high slip between the surfaces (low slip resistance). "Peak" or "static"
coefficient of friction is the highest instantaneous value obtained during the test. "Mean" or "dynamic"
coefficient of friction is the average of the values obtained during the sixty seconds of the test. In the tests performed on the examples herein, a Sintec Model 25 tester, which is available from Sintech, North Carolina was utilized. Five (5) 40-gram Class F stainless steel calibration weights and a coefficient of friction testing sled, weighing 200 ~ 0.25 grams was utilized.
The dry coefficient of friction test was conducted by placing a material sample on the testing sled and activating the Sintec Model 25 tester to draw the testing sled six (6) inches across a polished stainless steel friction test plate for sixty seconds. The wet coefficient of friction test was conducted by wetting the material on the testing sled with a given quantity of fluid, waiting 30 seconds before placing the test sled on the stainless steel friction test plate, and activating the tester.
To quantify and characterize the fluid absorbency attributes of various materials, various test procedures are conducted to measure the quantity of fluid absorbed into the fabric and to determine the amount for fluid retained within the fabric. One test used herein to measure the fluid absorbency of a material measures the ability of a material to 2 0 allow penetration of a fluid into the material. This test is referred to herein as the "run off°
test. In this procedure, 20 ml of a 0.85% saline solution is dispensed at the top of a section of material that is approximately 8 inches long and approximately 5.25 inches wide. The material is positioned on a 30 degree inclined surface. Any fluid not transmitted into the material will run off and be collected one inch from the edge of the sample and 2 5 measured.
An additional test used herein to measure the fluid absorbency capabilities of a material determines the rate at which a sample of absorbent material will absorb a liquid by measuring the time required for it to completely absorb a specified volume of liquid.
This test is referred to herein as the liquid absorption rate test, and measures the liquid 3 0 absorption rate of a material. As used herein, "liquid absorption rate" is the time required for a sample of absorbent material to become completely wet by the test liquid. In this test, 0.1 ml of the test liquid, which is water, is dropped from a pipette held at a 45 degree angle and adjacent to a 4 inch x 4 inch specimen onto the specimen. The time for the drop to be completely absorbed (as indicated by a lack of visual, specular reflection of

9 light) is measured. Test results are expressed in seconds. Three separate drops are timed on each specimen.
A "rewet test" may also be used to indicate the absorbency of a material. This test is used to determine the amount of fluid that is forced back through the surface of a pre-y saturated material when a specific load is applied to the material. The amount of fluid that comes back through the surface when the material is subjected to a specific load is called the "rewet" value. The more fluid that comes to the surface, the larger the "rewet" value.
Lower rewet values are associated with a dryer material. In this test, the specimen is placed on a flat surface with the absorbent side up. For materials without film backings, a baffle is placed beneath the specimen being tested to prevent migration of fluid through the specimen and onto the flat surface. The test block, which is placed above the specimen, includes a slot. The specimen is positioned on the surface so that the long dimension of the specimen is parallel to the long dimension of the slot. One ml of test fluid is dispensed onto the specimen through the slot and allowed to absorb into the material. The specimen is then removed from the test block. Pieces of blotter paper are weighed and placed on top of the specimen. A pressure of 1 psi is applied to the surface of the material, and is held fixed for three minutes. After the pressure is removed, the blotter paper is weighed. The difference in weight between the original blotter weight and the blotter after the absorption test is the rewet value reported herein.
2 0 To compare the absorbency of the fabric of the present invention with the absorbency of the absorbent fabric, one can take the difference between the absorbency of the absorbent material and the absorbency of the medical fabric, and divide this difference by the absorbency of the absorbent material.
A test for determining peel strength between laminate layers is described in U.S.
Patent No. 5,997,981, which is hereby incorporated by reference in its entirety. As described therein, a sample is tested to determine the amount of tensile force (commonly referred to as "peel strength") that is required to pull apart the selected attached layers of the specimen. Values for peel strength are obtained using a specified width of the specimen, clamp jaw width, and a constant rate at which the clamp jaws are moved apart 3 0 from one another. The sample size is 2 inches wide by 6 inches long. The attached layers of the sample are pulled apart, by hand, a sufficient amount to allow the layers to be clamped into position. A pair of clamps is then attached to the sample, each clamp being attached to one of the layers that are being separated. Each clamp has a pair of jaws, and each jaw has a surface in contact with the sample. The jaws hold the sample in the same plane, usually the vertical plane. At the beginning of the test, the clamps are separated by one inch. The jaw surface is 1 inch by at least 4 inches, and the clamps are moved apart from each other at a constant rate of extension of 300 mm/min. The clamps move apart at the specified rate to pull the layers apart. The sample is pulled apart so that the layers are at an angle of about 180° with respect to each other. The peel strength value is reported as peak load, in grams, and is the maximum force needed to completely separate the layers. The Sintech 2 tester, available from the Sintech Corporation, 1001 Sheldon Dr., Cary; N.C. 27513, the Instron Model TM, available from the Instron Corporation, 2500 Washington St., Canton, Mass. 02021, or the Thwing-Albert Model INTELLECT II available from the Thwing-Albert Instrument Co., 10960 Dutton Rd., Philadelphia, Pa. 19154, may be used for this test. The test may be performed with the specimen in the cross direction (CD) or in the machine direction (MD).
The existing fenestration materials discussed above and identified as Type 1, Type 2 and Type 3 materials were tested for slip resistance and absorbency. Table 1 reports the average values for dry and wet static and dynamic coefficients of friction for each material type, as well as the liquid absorption rate of each material type using the tests described herein. The coefficient of friction tests were performed on the materials along the direction of manufacture or machine direction ("MD") and the cross direction ("CD").
Table 1 also lists the static and dynamic values of the coefficients of friction for these materials when tested in both a dry and a wet condition. Three and six milliliters of water 2 0 were applied to the specimens for testing in the wet condition in the manner previously described.
Table 1 Type Type Type Sample Group No. 1 2 3 Static MD Dry 0.615 0.221 0.248 Static MD Wet 3 0.474 0.206 0.261 ml Static MD Wet 6 0.515 0.214 0.228 rnl Dynamic MD Dry 0.562 0.191 0.218 Dynamic MD Wet 3 0.420 0.192 0.246 ml Dynamic MD Wet 6 0.437 0.192 0.213 ml As illustrated by the values reported in Table 1, the Type 1 material showed the greatest slip resistance of the samples tested.

Examples of improved slip-resistant and absorbent materials suitable for use in surgical drapes or as a fenestration reinforcement material attached to the drape were produced by applying a meltspray of a low-tack adhesive onto the Type 3 material. Table 2 lists various properties for four amorphous polyalphaolefins (APAOs). These adhesives were obtained from Huntsman Corporation, Houston, Texas. As noted below, each APAO
has a relatively low melt viscosity and a short "open time", which is defined herein as the period of time that the hot melt adhesive retains most of its adhesive attachment capability. The data listed in Table 2 is available from the manufacturer.
Table 2 APAO Grade RT 2180 RT 2115 RT 2215 RT 2315 (2180) (2115) (2215) (2315) Propylene Propylene Ethylene Ethylene Description homopolymer homopolymercopolymerCopolymer Melt Viscosity 6000 1200 1200 1100 at 204C, mPascal-sec (ASTM D3236) Open Time, sec, 0 0 10 20 Kraft/Kraft at The amorphous polyalphaolefins (APAOs) listed in Table 2 were applied to Type material and these samples were tested for various attributes. The results of those tests are reported herein.
For some samples, the materials listed in Table 2 were applied to the spunbond surface of the Type 3 material using a melt spray technique utilizing meltblown processing equipment. The melt spray was in the form of small diameter filaments and/or microfibers, and were applied to the Type 3 material at 1 to 5 grams per square meter (gsm). The 2 0 meltblowing die had 30 holes per inch. The APAO melt and processing air temperatures were within the range of about 370-380°F. The quantity of adhesive added to the Type 3 fabric was determined by adjusting the speed at which the Type 3 material passed under the meltblowing die and the amount of polymer exiting the meltblown die. In the examples listed in Table 3, the Type 3 material moved at a speed between 10 and 50 feet per 2 5 minute (fpm).

Each value reported in Table 3 is the average of three measurements, each measurement being taken from a separate specimen within the sample group.
Water absorbency and COF values that are reported in Table 3 were measured using the above-described test procedures. The standard deviation for the coefficient of friction values is between about 5-8%.

Table 3 Sample Sample GSM of Static Dynamic COF Absorbency COF

Description Group No. APAO Dry Dry (sec) Type 1 4 0 0.841 0.684 53.3 Type 2 5 0 0.231 0.204 4.9 Type 3 6 0 0.269 0.237 0.8 Type 3 with 7 5 0.914 0.729 1.1 Type 3 with 8 2 1.194 0.894 0.6 Type 3 with 9 5 1.098 0.949 1.4 Type 3 with 10 2 1.296 0.911 0.5 Type 3 with 11 1 0.763 0.673 1.2 Type 3 with 12 5 1.362 1.122 1.4 Type 3 with 13 2 1.809 1.338 0.7 Type 3 with 14 1 1.035 0.879 1.3 As shown in Table 3, Samples 7-14 demonstrated an improved balance of absorbency and slip resistance characteristics.
To further confirm the advantages obtained by applying the hot melt adhesives of the types cited in Table 2 to absorbent reinforcement materials, the APAO
grades 2115 and 2215 were melt sprayed onto Type 3 fabric using a different meltblown processing arrangement. The samples listed in Table 4 were produced at adhesive melt temperatures in the range of about 370°F to about 380°F and air processing temperatures in the range of about 400°F to about 450°F. The meltblowing die had 10 holes per inch. The Type 3 material speed was in the range of about 25 feet per minute to about 50 feet per minute (fpm). The adhesives were applied to specimens to achieve a layer of adhesive of at least about 4 gsm.
The Type 3 fabric samples with 2115 and 2215 polymers were tested for coefficient of friction values before (15, 17) and after (16, 18) assembly into surgical drapes as fenestration reinforcement materials to ensure the retention of desired attributes. Table 4 reports the average static and dynamic coefficient of friction values for these samples, and indicates that the COF values remained higher than the COF
values for the Type 3 material without the slip-resistant layer, even after assembly.
Table 4 Sample Sample StaticStatic Static Dynamic Dynamic Dynamic DescriptionGroup MD MD MD Wet MD Dry MD Wet MD Wet No. Dry Wet 6 ml 3 ml 6 ml ml Type 3 15 0.892 0.516 0.496 0.892 0.516 0.457 with Adhesive Before Assembly Type 3 16 0.844 0.544 0.498 0.844 0.544 0.451 with Adhesive 2115 After Assembly Type 3 17 1.201 0.638 0.655 1.201 0.638 0.543 with Adhesive Before Assembly Type 3 18 1.043 0.575 0.619 1.043 0.575 0.516 with Adhesive 2215 After Assembly Each value reported in Table 4 is the average of three measurements, each measurement being taken from a separate specimen within the sample group.
The relative coverage of the melt sprayed fibers on the absorbent material and the fiber size was estimated from measurements made by melt spraying the same materials onto transparent film sheets at the same processing conditions. The fibers on the transparent film sheets were stained with Os04 for over 48 hours so that the adhesive fibers would absorb transmitted light. The measurements were obtained using the Quantimet 970 IA system. Using this tool, the area covered by the adhesive fibers, their diameter, and their orientation could be estimated.
The relative coverage of the adhesive fibers and the fiber size were estimated for the adhesives listed in Table 5. Samples 19-24 were prepared by melt spraying the adhesive onto the surface of the transparent film material. Fibers were melt sprayed onto the transparent film material at 1 to 5 grams per square meter (gsm). The meltblown die had 30 holes per inch. The APAO melt and processing air temperatures were within the range of about 370-380°F. The quantity of adhesive added to the transparent film material was determined by adjusting the speed at which the transparent film material passed under the meltblown die and the amount of polymer exiting the meltblown die.
In the examples listed in Table 5, the transparent film material moved at a speed between about

10 and 50 feet per minute (fpm).
Each value reported in Table 5 is the average of three measurements, each 2 0 measurement being taken from a separate specimen within the sample group.

Table 5 Sample Sample APAO Mean Fiber Diameter% Area Description Group No. (gsm) (gym) Covered Transparent 19 5 8.8 82.9 Film with Transparent 20 2 9.8 82.3 Film with Transparent 21 5 16.3 89.2 Film with Transparent 22 2 13.4 83.9 Film with Transparent 23 5 15.5 87.5 Film with Transparent 24 2 13.9 70.6 Film with As shown by the data in Table 5, the percent of area covered ranged from about 70% to about 90%, although other levels of coverage may be used in the present invention. Also as shown in Table 5, the mean fiber diameter ranged from about 9 to about 16 microns. Other levels of fiber diameter may also be suitable for use with the present invention.
The samples listed in Table 6 were produced by the same process that produced the samples reported in Table 4. Each value reported in Table 6 is the average ofi three measurements, each measurement being taken from a separate specimen within the sample group.

Table 6 Sample Sample Mean Fiber Standard Description Group Diameter Deviation (gym) No.

Type 3 with 15 12.3 3.0 Type 3 with 17 15.6 3.6 Table 7 reports values for COF, water absorbency and run-off for samples of a Type 3 material having 0 and 4 gsm of various adhesives applied to the material. The process utilized was the same process utilized to prepare the samples reported in Tables 4 and 6. Water absorbency, COF and the run off tests were conducted as described above. Standard deviation values for the coefficient of friction values reported in Table 7 are in the range of 5% to 8%. Each value reported in Table 7 is the average of three measurements, each measurement being taken from a separate specimen within the sample group.

Table 7 Sample Static Dynamic Sample Group Static COF Dynamic COF Water Run off, No. COF (wettedCOF (wettedAbsorbency(grams (dry) with (dry) With (secs) of water) mils mils water) water) Type 25 0.240 0.343 0.206 0.301 1.18 15.3 no adhesive applied Type 26 0.546 0.761 0.433 0.720 0.93 13.9 with gsm APAO

Type 15 0.711 0.697 0.481 0.661 1.08 14.6 with gsm APAO

Type 17 0.954 .771 0.682 0.726 1.02 14.5 with gsm APAO

As shown by the data in Table 7, the samples demonstrated adequate slip resistance under wet and dry conditions. Modified absorbency tests were performed on the samples listed in Table 8, the only modification to the test being the substitution of synthetic blood for water. Absorbency was measured using the rewet test procedure and absorbency test procedures described above. The results were consistent with the results reported in the previous tables in that the absorbent properties of the Type 3 material are retained despite the addition of the slip-resistant fibers to the Type 3 material. Each value reported in Table 8 is the average of three measurements, each measurement being taken from a separate specimen within the sample group.
Table 8 Sample Sample AdhesiveModified AbsorbencyModified Rewet Group (gsm) (sec) Blotter Difference No. (gms water) Type 1 27 0 97.1 +/- 24 1.492 Type 3 28 0 47.4 +/- 22 0.618 Type 3 with 17 4 57.7 +/- 5 I 0.645 A variety of processes may be utilized to apply these hot melt adhesives to the Type 3 material to achieve the necessary absorbency and slip resistance.
The 2115 hot melt adhesive was applied to a Type 3 material at speeds in the range of about 500 feet per minute using three types of hot melt spray nozzles available from ITW Dynatec (Hendersonville, TN). The UFD 17-2 type nozzles, designated in Table 9 as Nozzle type A, sprayed the hot melt adhesive into fibers that were deposited onto the fabric as a relatively uniform dispersion. The Omega nozzles (8 HPI), designated in Table 9 as Nozzle type B, sprayed the adhesive into fibers that were deposited in overlapping sine wave patterns. The nozzles were positioned 1.125" away from the fabric, and the adhesive was applied to the fabric at a distance of about 22 inches before the final processing step where the fabric is wound onto a roll.
2 0 Each value reported in Tables 8 and 9 is the average of at least three measurements, each measurement being taken from a separate specimen within the sample group. Standard deviation values are 5-8% of coefficient of friction values.

Table 9 Sample GSM of Nozzle Process Static Static Dynamic Dynamic Group 2115 Type Air COF COF COF COF
No. added Pressure(dry) (wetted (dry) (wetted to (psi) with 3 with Type 3 at mils 3 375- water) mils 400F water) 29 2 A 30 0.469 0.627 0.402 0.551 30 2 A 30 0.399 0.507 0.352 0.463 31 2 A 40 0.465 0.548 0.402 0.477 32 4 A 30 0.364 0.594 0.320 0.532 33 4 A 30 0.471 0.643 0.421 0.584 34 4 A 30 0.497 0.600 0.426 0.545 35 4 A 30 0.555 0.555 0.458 0.506 36 4 A 30 0.462 0.551 0.391 0.483 37 4 A 40 0.421 0.585 0.359 0.534 38 4 A 40 0.575 0.640 0.485 0.583 39 4 A 40 0.477 0.513 0.412 0.454 40 4 A 60 0.496 0.696 0.426 0.635 41 4 A 60 0.613 0.703 0.513 0.655 42 4 A 60 0.660 0.748 0.541 0.679 43 4 A 60 0.562 0.592 0.460 0.557 44 6 A 60 0.607 0.617 0.507 0.557 45 6 B 15 0.461 0.561 0.371 0.513 The values for the coefficient of friction reported in Table 9 are greater than coefficient of friction values for the Type 3 material without the adhesive, and still provide improved slip resistance. Still higher COF values may be achieved by further varying the processing conditions, as noted in Table 10.
The relative coverage and fiber size of meltsprayed fibers applied to Type 3 fabric at 500 ft/min via hot melt spray nozzles was estimated from measurements made using fibers meltsprayed at the same conditions onto paper sheets. The fibers were stained and measured by procedures previously described. Table 10 lists the process conditions used to apply the RT 2115 meltsprayed fibers to the paper and the corresponding measurements. The samples listed were produced at adhesive melt temperatures in the range of about 360°F to about 380°F and air processing temperatures in a range of about 400°F to about 450°F. RT 2115 adhesive was added at 4 gsm with a UFD 17-1, or Type C nozzle design. The nozzles were positioned 1.125" away from the paper for the adhesive application.
Table 10 Sample Gsm of Nozzle Process Air Mean Fiber% Area Group 2115 addedType Pressure Diameter Covered (psi) No. to Paper at 375-400F m 46 4 C 40 si 101.1 34.4 47 4 C 60 si 92.4 44.3 While the coverage values listed above are lower than those reported for adhesives applied via a meltblown process, the coefficient of friction values are still greater than Type 3 fabric without adhesive.
Table 11 shows coefficient of friction values for samples prepared using the same process as for the samples reported in Table 10, except that the slip-resistant material was added to the Type 3 material.
Table 11 Sample Static COF Dynamic COF

Group Static (wetted Dynamic COF (wetted with COF with 3 3 No. d mils water d mils water 48 0.821 0.778 0.639 0.737 49 0.849 0.911 0.702 0.837 It may be desirable, in some instances, to process the slip-resistant and absorbent material so that it can be wound into rolls soon after the slip-resistant material is added to the absorbent material. Improper processing may cause attachment of the slip-resistant top surface to the bottom surface after the fabric has been wound into rolls.
Higher basis weight additions of the adhesives, for example, 12 gsm, and other processing conditions 2 5 affecting fiber size may result in the inadequate solidification of the larger fibers of adhesive prior to winding of the fabric into rolls. The inadequate solidification of the larger fibers of adhesive can cause attachment between the layers of the slip-resistant and absorbent material, although it is possible to correct these issues with processing adjustments. For example, providing additional cooling time prior to winding may provide sufficient time for the larger fibers of adhesive to solidify sufficiently to prevent undesired adhesion between the layers of the slip-resistant and absorbent material.
To determine the level of attachment between the top surface and the bottom surface of the slip-resistant and absorbent material, samples were subjected to peel strength testing in the manner previously described. The RT 2315 and the RT

meltsprayed fibers were deposited onto Type 3 fabric via UFD 17-1 hot melt spray nozzles at 4 gsm at 500 feet per minute. The nozzles were positioned 1.125"
away from the fabric for the adhesive application. Table 12 reports MD peel strength values, determined per the test described herein, for samples of the RT 2315 meltsprayed onto the Type 3 fabric and placed against the bottom surface of a Type 3 fabric.
Each of the samples formed with RT 2115 did not show a measurable average or peak load, indicating that the layers were separated without the application of a measurable force.
Table 12 Sample Description Average Load Peak Load (g) (g) Group No.

50 RT 2315; No Chill Roll 21.26 45.43 6.70 std dev 15.77 std dev 51 RT 2315; Chill Roll 13.98 30.60 7.28 std dev 14.83 std dev Samples with RT 2315 applied to the surface resulted in measurable peel strength that is undesirable. Use of a chill roll during fabric processing decreased peel values.
2 0 Other processing aids and adjustments may enable a wide variety of slip-resistant surfaces to help to minimize unwinding issues during fabric converting.
Materials other than those listed in the above tables may also be used in the present invention. For example, any of a wide variety of adhesives, including those delineated above, may be applied to any of a number of absorbent materials, including multilayer 2 5 laminates. For example, an adhesive may be applied to an apertured film that is attached to or supported by an absorbent material. The apertured film permits fluid to pass through the film and into the absorbent materials positioned beneath the film where it is retained.
Such a fabric may thus exhibit both anti-slip and absorbent properties sufficient for use in surgical applications. While adhesives may be well-suited for this application, other 3 0 materials which provide slip-resistance may also be utilized.

As used herein, any given range is intended to include any and all lesser included ranges. For example, a range of from 45-90 would also include 50-90; 45-80; 46-89; and the like.
While the invention has been described in detail with respect to specific preferred embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to and variations of the preferred embodiments. Such alterations and variations are believed to fall within the scope and spirit of the invention and the appended claims.

Claims (35)

We claim:

1. A slip-resistant and absorbent material comprising:

an absorbent nonwoven fabric having a first surface and a second surface;
a layer of hot melt adhesive fibers applied to the first surface of the nonwoven web to form a slip-resistant surface; and a film attached to the second surface of the nonwoven fabric;

wherein the slip-resistant surface of the nonwoven material has a coefficient of friction of at least about 0.3, and the slip-resistant and absorbent material has an absorbency, as measured through the slip-resistant surface, of at least half the absorbency of the absorbent nonwoven fabric.

2. The material of claim 1 wherein the coefficient of friction is at least about 0.5.

3. The material of claim 1 wherein the coefficient of friction is at least about 0.6.

4. The material of claim 1 wherein the absorbency of the slip-resistant and absorbent material is at least 60% of the absorbency of the absorbent nonwoven fabric.

5. The material of claim 1 wherein the absorbency of the slip-resistant and absorbent material is at least 80% of the absorbency of the absorbent nonwoven fabric.

6. The material of claim 1 wherein the absorbency of the slip-resistant and absorbent material is at least 90% of the absorbency of the absorbent nonwoven fabric.

7. The material of claim 1, wherein the percentage of area of the first surface that is covered by the fibers is at least about 20%.

8. The material of claim 1, wherein the percentage of area of the first surface that is covered by the fibers is at least about 50%.

9. The material of claim 1, wherein the absorbent nonwoven fabric is a meltblown/spunbonded laminate nonwoven material.

10. The material of claim 1, wherein the adhesive is an amorphous polyalphaolefin.

11. A slip-resistant and absorbent material comprising:

an absorbent fabric having a surface; and fibers applied to the surface of the fabric to form a slip-resistant surface;
wherein the slip-resistant surface has a coefficient of friction of at least about 0.3, and the slip-resistant and absorbent material has an absorbency, as measured through the slip-resistant surface, of at least half the absorbency of the absorbent nonwoven fabric.

12. The material of claim 11 herein the absorbent fabric is a nonwoven fabric.

13. The material of claim 11 wherein the fibers are amorphous polyalphaolefin, natural rubber, synthetic rubber, or flexible polyolefins.

14. The material of claim 11, wherein the adhesive is an amorphous polyalphaolefin.

15. The material of claim 11 herein the coefficient of friction is at least about 0.4.

16. The material of claim 11 wherein the coefficient of friction is at least about 0.6.

17. The material of claim 11 wherein the absorbency of the slip-resistant and absorbent material is at least 60% of the absorbency of the absorbent nonwoven fabric.

18. The material of claim 11 wherein the absorbency of the slip-resistant and absorbent material is at least 80% of the absorbency of the absorbent nonwoven fabric.

19. The material of claim 11 wherein the absorbency of the slip-resistant and absorbent material is at least 90% of the absorbency of the absorbent nonwoven fabric.

20. The material of claim 11, wherein the percentage of area of the surface that is covered by the fibers is at least about 20%.

21. The material of claim 11, wherein the percentage of area of the surface that is covered by the fibers is at least about 40%.

22. The material of claim 11, wherein the percentage of area of the surface that is covered by the fibers is at least about 70%.

23. A medical fabric comprising:

an absorbent fabric having a slip-resistant material applied to a surface of the absorbent fabric forming a slip-resistant surface, the medical fabric having an absorbency, as measured through the slip-resistant surface, of at least half the absorbency of the absorbent material, the slip-resistant surface having a coefficient of friction of at least about 0.3.

24. The material of claim 23 wherein the coefficient of friction is at least about 0.5.

25. The material of claim 23 wherein the coefficient of friction is at least about 0.6.

26. The material of claim 23 wherein the absorbency of the slip-resistant and absorbent material is at least 60% of the absorbency of the absorbent nonwoven fabric.

27. The material of claim 23 wherein the absorbency of the slip-resistant and absorbent material is at least 80% of the absorbency of the absorbent nonwoven fabric.

28. The material of claim 23 wherein the absorbency of the slip-resistant and absorbent material is at least 90% of the absorbency of the absorbent nonwoven fabric.

29. The material of claim 23, wherein the absorbent fabric is a nonwoven material

30. The material of claim 29, wherein the nonwoven material includes a meltblown layer and a spunbonded layer.

31. The material of claim 23, wherein the slip-resistant material is an amorphous polyalphaolefin.

32. The material of claim 23, wherein the percentage of area of the surface that is covered by the slip-resistant material is at least about 20%.

33. A surgical drape including the material of claim 23.

34. A surgical drape fenestration material including the material of claim 23.

35. A method of forming a slip-resistant and absorbent material including the steps of:

providing an absorbent material having a first and second surface; and applying a meltspray of fibers of a slip-resistant material to the first surface of the absorbent material so that the absorbency of the slip-resistant and absorbent material is at least half of the absorbency of the absorbent material;

packing the material so that the fibers of the slip-resistant material are adjacent to the second surface of the absorbent material, peel away from the adjacent material without sticking to the adjacent material.