HK1025074A - Improved cloth-like, liquid-impervious, breathable composite barrier fabric - Google Patents

Description

Improved cloth-like liquid-impermeable breathable composite barrier fabrics

Technical Field

The present invention relates to cloth-like, liquid-impermeable, breathable composite barrier fabrics. In particular, the present invention is directed to cloth-like, liquid-impermeable, breathable film-nonwoven composite fabrics having the ability to retain biological fluids, and which are useful, for example, as antiseptic garments, surgical drapes, surgical gowns, such as coats, and the like.

Background

Surgical gowns, surgical drapes, surgical masks, and antiseptic coats and separate antiseptic garment bags (hereinafter collectively referred to as "surgical articles") must be balanced in terms of properties, characteristics, and performance characteristics in order to function satisfactorily. Such surgical articles are primarily designed to substantially reduce, if not prevent, the transmission of biological fluids and/or airborne contaminants therethrough. In a surgical treatment environment, such sources of liquid include perspiration of the wearer of such pajamas, body fluids of the patient, such as blood, life support fluids such as plasma and saline. Examples of airborne contaminants include, but are not limited to, biological contaminants such as bacteria, viruses, and mold spores. Such contaminants may also include particulate materials such as, but not limited to, lint, mineral fines, dust, skin debris, and respiratory droplets. A measure of the ability of a barrier fabric to prevent the passage of such airborne materials is sometimes expressed in terms of filtration efficiency.

Such surgical articles should also be comfortable in use, i.e. in wear. The breathability, i.e. the water vapor transmission rate, of a surgical article is an important measure of its comfort in use. Other characteristics of the surgical article that contribute to its comfort during use include, but are not limited to, its drape ability, cloth-like feel, hand feel, cold feel, and dry feel.

Surgical articles also need to have a minimum level of strength and durability to provide the necessary degree of safety to the user of the article, particularly in surgical procedures.

Finally, surgical articles are preferably inexpensive to produce, utilize lightweight materials to improve wearer comfort during use, and also reduce the cost of such articles.

Liquid impermeable, breathable, multi-layer barrier fabrics employing a variety of structures are known. Surgical articles formed from liquidphobic fabrics, such as those formed from nonwoven fabrics or layers of yarns, have provided acceptable liquid impermeability, breathability, cloth-like drape, strength and durability, and low cost. However, there remains a need for improved cloth-like, liquid-impermeable, breathable barrier materials for use in forming surgical articles and for use in other garments and gowns, such as personal protective equipment (e.g., coveralls), wherein some or all of the above-described performance characteristics and features are desirable or necessary. Other personal protective equipment applications include, but are not limited to, laboratory uses, clean room uses such as in semiconductor manufacturing, agricultural uses, mining uses, environmental uses, and the like.

In addition, body attachable articles such as adult incontinence products and baby or child diapers or garments such as training pants may employ components having the desired properties described above.

Summary of The Invention

It is therefore an object of the present invention to provide an improved cloth-like, liquid-impermeable, breathable barrier material that achieves a superior balance of performance characteristics and features suitable for use in apparel, gowns, and personal protective equipment, including use as surgical articles.

More specifically, it is a first object of the present invention to provide such an improved cloth-like liquid-impermeable, breathable barrier material which is effective in blocking the passage of biological fluids and which meets the measurements required by the astm es21 test method.

It is a further object of this invention to provide such an improved cloth-like, liquid-impermeable, breathable barrier material which is highly comfortable to wear. The barrier materials of the present invention exhibit a high level of breathability, for example, a Water Vapor Transmission Rate (WVTR) of at least 1000 grams per square meter per 24 hours as measured by the test method described herein. The barrier material of the present invention also exhibits textile-like drapeability with a drape stiffness of < 4.0 cm, as measured according to the test method described herein.

It is a further object of this invention to provide such an improved cloth-like, liquid-impermeable, breathable barrier material having suitable strength and durability for its intended use, having a peak grab tensile energy of at least about 15 inch-pounds force in the machine direction and at least about 19 inch-pounds force in the cross-machine direction; and a peak strain in the machine direction of at least about 35% and a cross-machine direction of at least about 70%.

It is a further object of this invention to provide such an improved cloth-like, liquid-impermeable, breathable barrier material which is lightweight, relatively inexpensive to manufacture, and has a basis weight of less than about 2.0 ounces per square yard²。

These and other objects are achieved by the improved cloth-like, liquid-impermeable, breathable barrier material disclosed and claimed herein.

Brief description of the drawings

FIG. 1 is a cross-sectional view of a barrier material of the present invention;

figure 2 schematically illustrates a process for making the barrier material of the present invention.

Detailed description of the invention

The present invention is directed to an improved cloth-like, liquid-impermeable, breathable barrier material having a good balance of performance characteristics and features that make it suitable for use in the manufacture of surgical articles, as well as in other garments and gowns, such as for personal protective equipment. Embodiments of the barrier material of the present invention are described with reference to the accompanying drawings. The barrier material 10 is a laminate comprising three layers: a nonwoven top layer 12, for example formed from spunbond fibers; a nonwoven bottom layer 16, for example formed from spunbond fibers; the breathable intermediate layer 14 is formed, for example, from a microporous membrane. The layers of barrier material 10 are bonded using known methods including thermo-mechanical bonding, ultrasonic bonding, adhesives, stitching, and the like. Laminated, adhered or attached together.

As used herein, a "layer" or "fabric" when taken alone can have the dual meaning of a single piece or multiple pieces. As used herein, "laminate" refers to a composition of two or more layers of fabric material that have been bonded or otherwise joined to one another. As used herein, "nonwoven fabric" or "nonwoven web" refers to a fabric having a structure of individual fibers or filaments interlaid, but not in an identifiable and repeating manner as in a knitted or woven fabric.

Commercially available thermoplastic polymeric materials may be well suited for making the fibers or filaments of the nonwoven top and bottom layers 12, 16 formed therefrom. As used herein, "polymer" shall include, but is not limited to, homopolymers; copolymers such as block, graft, random and alternating copolymers; terpolymers, etc., and mixtures and modifications thereof. Further, unless otherwise specifically limited, "polymer" shall include all possible geometric configurations of such polymeric materials, including, but not limited to, isotactic, syndiotactic, random, and random symmetric configurations. As used herein, "thermoplastic polymer" or "thermoplastic polymeric material" refers to a long chain polymer that softens when exposed to heat and returns to a solid condition when cooled to room temperature. Typical thermoplastic materials include, but are not limited to, polyvinyl chloride, polyester, polyimide, polyfluorocarbon, polyolefin, polyurethane, polystyrene, polyvinyl alcohol, caprolactam, and copolymers thereof.

The nonwoven fabrics that can be used in the nonwoven layers 12 and 16 of the present invention can be made by a variety of known forming processes including spunbond, airlaid, meltblown or bonded carded fabric forming processes. For example, in the illustrated embodiment of the invention, both the top layer 12 and the bottom layer 16 are spunbond nonwovens, which have proven advantageous for forming the barrier material 10. Spunbond nonwoven fabrics are made from meltspun filaments. As used herein, "melt spinning" refers to the formation of small diameter fibers and/or filaments from a plurality of fine, usually circular capillaries of a spinneret by extruding a molten thermoplastic material into filaments whose diameters are then rapidly reduced by, for example, non-aspirating or aspirating fluid drawing or other well-known spunbonding mechanisms. Finally, these melt-spun filaments are deposited in a substantially random manner onto a moving carrier tape or similar device to form a substantially continuous and randomly arranged melt-spun web. Spunbond filaments are generally not bonded when they are deposited onto a collecting surface. The production of such spunbond nonwoven fabrics has been described in U.S. Pat. Nos. 4340563(Appel et al), 3692618(Dorschner et al), 3802817(Matsuki et al), 3338992 and 3341394(Kinney), 3502538(Peferson) and 3542615(Dobo et al), all of which are incorporated herein by reference. Melt-spun filaments formed by the spunbond process are generally continuous and have an average diameter greater than 7 microns (microns) based on at least 5 measurements, and more particularly between about 10 and 100 microns. Another commonly used expression for fiber or filament diameter is denier, which is defined as grams per 9000 meters of fiber or filament.

Spunbond fabrics are stabilized or cured (prebonded) in some manner immediately after their production so that the fabric has sufficient integrity and strength to withstand the rigors of further processing into a finished product. This pre-bonding step may be accomplished by applying a heat-activatable adhesive in liquid or powder form to the filaments, or more generally by a pressure roller. As used herein, "pressure rollers" means a set of rollers above or below the nonwoven fabric used to press the fabric as a means of treating the as-produced meltspun filaments, particularly spunbond fabrics, to provide sufficient integrity for further processing of the fabric, but not to provide stronger bonds by subsequent auxiliary bonding treatments such as through air bonding, thermal bonding, ultrasonic bonding, and the like. The compaction rollers are slightly squeezing the fabric to enhance its self-adhesion and thus its integrity.

A typical secondary bonding process thermally bonds the spunbond fabric using an embossing roll assembly, which generally includes an embossed bond roll and a smooth anvil roll, which together define a heated embossed bond nip. Alternatively, the anvil roll may carry a bonding pattern on its outer surface. The embossing roll is heated to a suitable bonding temperature by conventional heating means and rotated by conventional drive means to form a series of thermal patterns as the spunbond web passes through the nip. Given the line speed, bonding temperature, and material forming the web, the nip pressure in the nip should be sufficient to achieve the desired degree of bonding of the web. For such spunbond fabrics, the percent bond area is typically from about 10% to about 20%.

The breathable intermediate film layer 14 can be formed of any microporous film that is suitably bonded or attached to the topsheet 12 and backsheet 16 to form the barrier material 10 that advantageously combines the performance characteristics and features described herein. One suitable class of film materials comprises at least two essential components: a thermoplastic elastomeric polyolefin polymer and a filler. These components (and other components) can be mixed together, heated and then extruded into a single or multilayer film using any of a variety of film production methods well known to those in the film processing arts. Such film-making processes include, for example, cast embossing, chill casting, and flat casting, as well as blown film processes.

Generally, film layer 14 will comprise from about 30 to about 60 weight percent of a polymer of a thermoplastic polyolefin, or mixtures thereof, and from about 40 to about 70 weight percent of a filler, based on the total weight of the film, on a dry weight basis. Other additives and formulations may be added to the film layer 14 so long as they do not significantly interfere with the ability of the film layer to function in accordance with the principles of the present invention. Such additives and ingredients include, for example, antioxidants, stabilizers, and pigments.

The film layer 14 includes a filler in addition to the polyolefin polymer. As used herein, "filler" includes particulate and other forms of material that can be added to the film polymer extrusion mixture without chemically interfering with the extruded film, while being uniformly dispersed throughout the film. Generally, the filler is in particulate form, and may be spherical or non-spherical, with an average particle size of about 0.1 to about 7 microns. Both organic and inorganic fillers are within the purview of the present invention so long as they do not interfere with the film forming process or enable the film layer to function as claimed in the present invention. Suitable fillers include calcium carbonate (CaCO)₃) Various kinds of clay, Silica (SiO)₂) Alumina, barium carbonate, sodium carbonate, magnesium carbonate, talc, barium sulfate, magnesium sulfate, aluminum sulfate, titanium dioxide (TiO)₂) Zeolite, cellulose type powder, kaolin, mica, carbon, calcium oxide, magnesium oxide, aluminum hydroxide, wood pulp powder, wood flour, cellulose derivatives, chitin and chitin derivatives. If desired, a suitable coating, such as stearic acid, may be applied to the filler particles.

As described above, the film layer 14 may be formed by any conventional method known to those familiar with film forming processes. The polyolefin polymer and the filler are mixed in the ranges given above and then extruded into a film by heating. To liftFor uniform breathability, as reflected by the water vapor transmission rate of the film layer, the filler should be uniformly dispersed throughout the polymer mixture and thus throughout the film layer itself. For the purposes of the present invention, water vapor transmission rates of at least 300 g/m, when calculated by the test methods described above, are²At 24 hours (g/m)²At/24 hr), the film is considered "breathable". Generally, once formed, the film layer will have a weight per unit area of less than about 80 grams/meter²(gsm) and after stretch thinning, has a basis weight of from about 10 to about 25 gsm.

The film layers used in the examples of the invention described below are single layer films, but other types of film layers, such as multilayer films, are also within the scope of the invention, as long as the forming technique can be matched to the filled film. Such films are generally thick and generate extraordinary noise when they are initially formed, which tends to "click" when shaken. In addition, such as-formed film does not have a sufficient degree of air permeability as calculated from its water vapor transmission rate. To this end, the film is heated to a temperature at or below the melting point of the polyolefin polymer at about 5 ° and then the film is stretched to at least 2 times its original length (2 ×) using a linear Machine Direction Orientation (MDO) apparatus to thin and render the film porous. The film 14 is further stretched to about 3 (3x), 4 (4x) or more times its original length, which is apparent in connection with the film 14 formed in accordance with the present invention.

The film layer 14 should have an "effective" film thickness or film thickness of about 0.2 to about 0.6 mils (mil) after being stretched and thinned. This effective thickness is used to reference the pores or air gaps in the breathable film layer. For a typical unfilled impermeable membrane, the actual thickness and effective thickness of the membrane are the same. However, for films which have been stretch-filled, as mentioned above, air gaps will be included in the thickness of the film, and to disregard this added volume, the effective thickness can be calculated according to the test methods described below.

Referring to fig. 2, a process for continuously preparing the barrier material 10 of the present invention is illustrated. The film layer 14 is formed by using an optional type of conventional film forming apparatus 20 such as a casting film or a blowing film apparatus. The film layer 14 with the formulation is then stretched by passing it through a film stretching apparatus 22 and thinning the film to an effective thickness of 0.6 mils or less. One suitable film stretching apparatus is a machine direction orientation device, model 7200, available from Marshall & Williams Company, having business place Providence, Rhode Island.

While the film layer 14 is stretched, the spunbond nonwoven layers 12 and 16 are formed. As noted above, conventional spunbond nonwoven manufacturing processes may be used to form the nonwoven layers 12 and 16. As shown in FIG. 2, the spunbond fabrics 12, 16 are formed from substantially continuous and randomly arranged melt-spun filaments deposited from extruders 28A, 28B, 29A, 29B onto moving continuous forming wires 24, 26. Such webs of randomly arranged meltspun filaments may then be pre-bonded by passing each web 12, 16 through a pair of nip rolls (not shown) to impart sufficient bulk and strength to the webs 12, 16 for further processing. One or both of the pressure rollers may be heated to assist in the bonding of the fabrics 12, 16. Typically, one of the pair of pressure rollers has a patterned outer surface that imparts a discrete bond pattern having a defined bond area to the fabric 12 and/or the fabric 16. The other pressure roller opposite thereto is typically a smooth anvil roller, but this roller may also have a knurled outer surface, if desired.

After the film layer 14 has been sufficiently stretch reduced and oriented and the spunbond fabrics 12, 16 have been formed, the three layers are brought together and laminated to one another using a pair of laminating or bonding rolls 30, 32 as shown in FIG. 2, or other conventional bonding means, to produce the barrier material 10 of the present invention.

As shown in fig. 2, the bonding roll 30 is an embossing roll and the second bonding roll 32 is a smooth roll. Both rollers are driven by a transmission means such as an electric motor (not shown). The patterned roll 30 is a right circular cylinder and may be formed of any suitably durable material, such as steel, to reduce wear of the roll during use. The outermost surface of the embossing roll 30 has a pattern of raised bonding areas. As is generally the case in the art, for example, an intermittent pattern of discrete, regularly repeating adhesive dots may suitably be employed. The bonding zones on the embossing roll 30 form a nip with the smooth or flat outer surface of an oppositely disposed anvil roll 32, which is also a right circular cylinder, and may be formed of any suitable durable material, such as steel, hardened rubber, resin treated cotton, or polyurethane.

The pattern of raised bonding areas on the embossing roll 30 is selected so that at least one surface of the resulting barrier material 10 is occupied by adhesive in an area that is between about 10% and about 30% of the surface area of the barrier material after passing through the gap formed between the rolls 30, 32. The bond area of the barrier material 10 may be varied to achieve the percent bond area described above, as is well known in the art.

The temperature of the outer surface of patterned roll 30 may be changed by heating or cooling relative to smooth roll 32. Heating and/or cooling may affect, for example, the degree of lamination of the layers forming the barrier material 10. Heating and/or cooling of the patterned roll 30 and/or smooth roll 32 may be performed by conventional means (not shown) well known in the art. The particular temperature range employed in forming the barrier material 10 depends on a number of factors including the type of polymeric material used in the layers forming the barrier material 10, the residence time of the layers in the nip, and the nip pressure between the embossing roll 30 and the anvil roll 32. As the barrier material 10 exits the nip formed between the bonding rolls 30, 32, the material 10 may be wound onto a roll 34 for subsequent processing.

Modifications to the above would be obvious to those of ordinary skill in the art, but would not bring the invention so modified beyond the spirit and scope of the present invention. For example, after the barrier material 10 is formed, it may continue to be further processed or transformed on the wire. Alternatively, a different apparatus may be used to stretch the thinned film layer 14. Other known means may be employed to bond and laminate the film layer 14 to the nonwoven layers 12, 16 so long as the resulting barrier material 10 has the desired properties described above. Finally, the film layer 14 and/or nonwoven layers 12, 16 may be formed at a remote location, with each layer in a rollThe plies are unwound from a reel and fed into a nip formed between an embossing roll 30 and a smooth roll 32. Furthermore, in certain applications, it may be advantageous, for example, to dispense with one of the two spunbond fabrics and form a bicomponent material as described above. Typical spunbond fabric weights for such applications range from about 0.6 to about 1.5 ounces per square yard²(osy) and typically about 0.9-1.3 osy. Such materials may be laminated to the stretch thinned film by heating or bonding to form a composite.

Having described certain examples of the present invention, an array of sample barrier materials was tested to further illustrate the present invention and to indicate to the skilled artisan the manner in which the present invention may be practiced. The results of measuring certain physical properties of the barrier material thus formed and the test methods used are set forth below. As a comparison, the same physical properties were measured for several commercially available barrier materials. The results reported here are the average of the values obtained for 5 measurements of various properties for each sample and for the barrier materials used for comparison.

Test method

The following test methods were used to analyze the samples indicated below and comparative barrier materials.

Effective thickness

The effective thickness of the film is calculated from the density of the polymer and filler forming the film divided by the basis weight of the film. To obtain the effective thickness of the film in inches, the measured weight per square yard ounce (osy) per unit area is multiplied by 0.001334 (a unit conversion factor of metric to english) and the result is divided by grams/cm³(g/cc) is the density of the polymer composition in units.

Tensile Strength and elongation test

The grab strength test for tensile strength and elongation measures the load at break and percent elongation before break, i.e., "stretchability" of the material. These measurements were made under a continuously increasing load of the material in a single direction at constant elongation. Test procedures were strictly in accordance with ASTM standards D-5035-92 and INDA IST110.1-92, using a constant speed elongation tester such as the Sintech System 2 computer integrated test System, manufactured by MTS systems Inc. of Eden Prairie, Minnesota.

For each sample material, 5 samples were cut with a 4 inch (100 mm) wide precision cutter, each 4 inches (100 mm) wide and 6 inches (150 mm) long, with the long dimension parallel to the direction of the test and force. The test specimen was placed in a fixture in a constant rate elongation tester. Each sample is set so that its length or long dimension is as parallel as possible to the direction of action of the force. A continuous load was applied to the specimen and the crosshead speed (load rate) was set at 300 mm/min until the specimen broke. The peak load, peak energy and peak strain were recorded as well as the average. The measurements in the Machine Direction (MD) and cross-machine direction (CD) are recorded separately.

Water vapor transmission rate

The Water Vapor Transmission Rate (WVTR) of the sample material was calculated according to ASTM Standard E96-80, and a 3-inch diameter circular sample was cut from each of the test material and a comparative material, which was a piece of CELGARD^2500 membranes, available from Hoechst Celanese corporation of Sommerville, N.J.. CELGARD^The 2500 membrane was a microporous polypropylene membrane, and three samples were prepared for each material. The test dish was a No.60-1 volatility meter dish, available from the Thwing-Albert Instrument Company of Philadelphia, Pennsylvania. 100 milliliters (me) of distilled water was poured into each volatility meter pan while each sample of both sample and contrast material was placed across the open top end of each pan, a screw flange was fastened, a seal was formed along the edge of each pan (no sealing paste used), the associated test or contrast material was exposed to ambient atmosphere to a 6.5 centimeter diameter circle having an exposed area of about 33.17 centimeters². The trays were weighed and then placed in a forced draft oven at 37 ℃. The furnace is a constant temperature furnace through which external air circulates to prevent water vapor from accumulating inside. A suitable forced draft oven is, for example, Blue M Power-O-Matic 60Furnace, purchased from Blue M Electric Co of Blue Island, Illinois. After 24 hours, the pan was removed from the oven and weighed again. The water vapor transmission rate values for this preliminary test were calculated as follows:

test WVTR (g/m)²24 hours) — (g weight loss after 24 hours) × 315.5 g/m²The relative humidity in the/24 hour furnace was not specifically controlled.

Under preset conditions of 100 DEG F (32 ℃) and ambient relative humidity, CELGARD^The WVTR of 2500 films has been determined to be 5000 grams/meter²24 hours (g/m)²24 hr). Thus, each test was carried out on the comparative sample while correcting the preliminary test values with respect to the set conditions using the following formula:

WVTR (g/m)²24 hours) — (test WVTR/comparative WVTR) × 500 g/m²24 hours

Basis weight

The basis weight of the sample material was determined according to Federal test method No. 191A/5041. The sample size of the sample material was 15.24 cm × 15.24 cm, and 5 values were obtained for each material and then averaged.

Hydrostatic pressure test

Hydrostatic pressure test measures the resistance of a nonwoven to penetration by water at low hydrostatic pressures. The test procedure was modified to include a standard synthetic fiber window material in accordance with method 5514-federal test method standard No.191A, AATCC test method 127-89 and ZNDA test method 80.4-92.

A Textest FX-300 hydrostatic head tester is available from Schmid Corp, having the trade name Spartanburg, South Carolina, the test head of which is filled with purified water. The purified water was maintained at a temperature of 65 ° F-85 ° F (18.3 ℃ -29.4 ℃), which was tested in a range of standard environmental conditions (about 73 ° F (23 ℃) and about 50% relative humidity), and test material from an 8 inch x 8 inch (20.3 cm x 20.3 cm) square specimen was placed in a reservoir completely covering the test head. The sample was placed under standard water pressure and the water pressure was increased at a constant rate until leakage was observed on the outer surface of the sample material. Hydrostatic resistance was measured at the onset of leak signs in three separate areas of the sample. This test was repeated for 5 samples of each sample material. The hydrostatic resistance obtained for each sample was averaged and the results were recorded in mbar. Higher value surfaces offer greater resistance to fluid penetration.

Cup crush test

The cup crush test is a test in which the material is softer when the peak load value is lower, as measured by the isokinetic elongation tensile tester using peak load and energy units.

The test procedure was conducted in a controlled environment at a temperature of about 73F (23 c) and a relative humidity of about 50%. The samples were run using the previously described Sintech System 2 computer Integrated test System and the crush test stand was purchased from Kimberly-Clark Corp quality assessment in Neenah, Wisconsin and included a model 11 bracket, a model 31 steel ring, a base plate, a model 41 cup assembly and a calibration device.

The steel ring was placed on the forming cylinder and a 9 inch by 9 inch (22.9 cm by 22.9 cm) specimen was centered over the forming cylinder. The forming cup is slid over the forming cylinder until the sample is completely sandwiched between the forming cylinder and the steel ring around the steel ring. The forming cup is placed on top of the load chamber and sits securely on the back of the base plate. The crosshead speed was set at 400 mm/min, the frame was mechanically lowered into a forming cup, the specimen was crushed, and the peak load (in grams) and energy (in grams. mm) required to crush the specimen were measured by a constant rate elongation tensile tester. The peak load and energy for each sample material for 5 samples were averaged and reported.

Drape stiffness test

The drape stiffness test measures the bending length of a fabric using the cantilever bending principle of the fabric under its own drape. This test method measures the resistance of a fabric to bending for drape stiffness. The bending length is used to measure the interaction between the fabric weight and the fabric stiffness as indicated by the fabric when it bends under its own sag. It reflects the stiffness of the fabric to bend in one plane under gravity.

A 1 inch x 8 inch (2.54 cm x 20.32 cm) specimen was slid parallel to its long dimension at a speed of 4.75 inches/minute (12.07 cm/minute) with its front edge protruding from the edge of the horizontal surface. The length of the protruding portion was measured when the tip end of the test specimen was pressed down by the self weight of the test specimen until the line connecting the tip end to the edge of the test stand was at an angle of 41.5 ° to the horizontal. The longer the extension, the slower the fabric is bent, and thus a higher value indicates that the fabric is stiffer.

This test procedure is in accordance with ASTM Standard test D1388, except that the dimensions of the test specimens are as described above. MD and CD measurements of the bending length were made and recorded, respectively, using a cantilever bending tester such as model 79-10 available from test machines corporation, Amityville, New York.

The drape stiffness was calculated as follows:

drape stiffness (cm) — bending length (in) × 2.54 an average value of drape stiffness is reported here.

Examples of the present invention

Sample No.1

The barrier material of the present invention was prepared. The film layer comprises the following components by weight percent: 13% Shell 6D82 Polypropylene/polyethylene copolymer containing 5.5% ethylene; 18% Rexene FD-D1700 low crystallinity polypropylene having atactic stereoisomers of high molecular weight polymer chains; 3% Dow5004 with 60000ppm Irgafos168 as an antioxidant and stabilizer; 2% SCC12673 blue concentrate, available from stonridge colorcorp; and 64% of English China Supercoat calcium carbonate (CaCO)₃) Coated with 1.5% behenic acid, having an average particle size of 1 micron and a top kerve of 7 microns. Such carbonic acidCalcium was purchased from ECCA Calcium Products, Inc, in Sylacauga, Alabama, a division of ECC International. The film material is blown into a single-layer film.

The spunbond layers on both the top and bottom surfaces were 0.6 oz/yd²Is formed from an extrudable thermoplastic resin comprising: 97% Shell 6D43 random copolymer of propylene and ethylene monomer containing 3% ethylene; 2% titanium dioxide (white); 0.09% of an antistatic compound and 0.91 SCC11111 blue concentrate. Such spun bond filaments are essentially continuous in nature with an average fiber size of 2.0 dpf.

The film and top and bottom nonwoven layers are laminated together as previously described with a thermal bonding roll. The bonding temperature of the patterned roll was about 185 ° F and the temperature of the smooth anvil roll was about 145 ° F. The nip pressure formed between the two rolls was about 440 psig.

Comparative example 2

Trial 3 a commercially available Baxter Vira Block surgical gown.

Comparative example 3

Trial 3 a commercial 3M surgical gown with a Prevention fabric was used.

Comparative example 4

Trial 3 a commercial Baxter Optima standard surgical gown.

Comparative example 5

Test 3A standard surgical gown available from Evolution3 of Kimberly-Clark Corp.

All measurements shown in the following two tables were taken from the body portion of various surgical gowns. All values shown are averages based on 5 measurements. TABLE 1

Test specimen	Basis weight (osy)	MD Peak load (lb)	Sample grabbing peak energy (in-lb)	Tensile Peak Strain (%)	CD peak load (lb)	Sample grabbing peak energy (in-lb)	Tensile Peak Strain (%)
								1	1.844	23.015	15.605	39.306	16.676	19.073	71.458
2	2.681	28.451	14 877	34.748	21.507	18.216	54.796
								3	1.822	29.929	30.191	57.490	22.995	29.697	70.650
4	2.239	27.332	12.174	28.230	15.763	17.164	77.252
								5	1.579	19.648	13.237	37.172	14.844	12.486	51.040

TABLE 2

Test specimen	Fluid pressure head (mbar)	WVTR(g/m2/24hr)	Cup energy (g/mm)	Crushing load (g)	Drape stiffness (MD) (cm)	Drape stiffness (CD) (cm)
							1	250.00	3019.45	2940.12	163.99	3.580	2.240
2	250.00	1628.82	4975.54	284.27	3.890	3.020
							3	250.00	4308.00	3829.26	189.16	2.190	2.230
4	26.6	4846.97	5514.46	317.65	4.100	2.180
							5	54.6	4861.78	2954.77	154.94	3.370	2.520

The data in tables 1 and 2 clearly show that the barrier material 10 of the present invention advantageously combines the physical characteristics and properties of low basis weight, good strength and durability, barrier properties, breathability, and the like of textiles, drape and softness.

It should be appreciated that the improved cloth-like, liquid-impermeable, breathable barrier materials constructed in accordance with the present invention can be adjusted and modified by the average person to accommodate varying degrees of performance requirements in actual use. Thus, while the invention has been described above with reference to certain specific embodiments and examples, it is to be understood that the invention is capable of other configurations. This application is therefore intended to cover any variations, uses, or adaptations of the invention following, in general, the principles thereof, and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the following claims.

Claims (23)

1. A cloth-like, liquid-impermeable, breathable barrier material comprising:

at least one nonwoven layer;

a microporous film layer bonded to said nonwoven layer to form a laminate, said laminate being breathable and having a measured WITR of at least 300 gm/m²24 hours and has a basis weight of about 2.0 ounces per yard²Or less, a peak energy in the machine direction of at least 15 inches per pound, a peak strain in the machine direction of at least about 35%, a peak energy in the cross-machine direction of at least about 19 inches per pound, and a peak strain in the machine direction of at least about 19 inches per poundAbout 70%, a hydrostatic head of about 250 millibar (mbar) or greater, a cup crush peak load of less than about 180 grams, a cup compression energy of less than about 3000 grams/millimeter, a drape stiffness in the machine direction of less than 4.0 centimeters, and a drape stiffness in the cross-machine direction of less than 3.0 centimeters.

2. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 further comprising first and second nonwoven layers.

3. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the nonwoven layer comprises a spunbond fabric.

4. The cloth-like, liquid-impermeable, breathable barrier material of claim 2 wherein the first and second nonwoven layers comprise first and second spunbond fabrics.

5. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the film layer is a single layer film.

6. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the film layer is a multilayer film.

7. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the laminate has a water vapor transmission rate of at least 1000 grams/meter²And/24 hours.

8. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the laminate has a water vapor transmission rate of at least 3000 grams/meter²And/24 hours.

9. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the nonwoven layer comprises about 98% random copolymer of both polypropylene and polyethylene having an ethylene content of 3%.

10. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 wherein the film layer comprises, in percent by weight based on its total weight, from about 40 to about 70 percent of the filler and from about 30 to about 60 percent of the polyolefin polymer, or mixtures thereof.

11. The cloth-like, liquid-impermeable, breathable barrier material of claim 1, consisting essentially of a nonwoven layer and a film layer.

12. A surgical gown comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 1.

13. A surgical gown comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 11.

14. A surgical drape comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 1.

15. A surgical drape comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 11.

16. A surgical breakaway garment bag comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 1.

17. A surgical breakaway garment bag comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 11.

18. An industrial protective garment comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 1.

19. An industrial protective garment comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 11.

20. The cloth-like, liquid-impermeable, breathable barrier material of claim 1 which comprises a thermoplastic elastomeric polyolefin.

21. The cloth-like, liquid-impermeable, breathable barrier material of claim 11 which comprises a thermoplastic elastomeric polyolefin.

22. A personal care product comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 1.

23. A personal care product comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 11.