CN1241966A - Improved cloth-like, liquid-impervious, breathable composite barrier fabric - Google Patents

Abstract

The present invention is directed to cloth-like, liquid-impervious, breathable composite barrier fabrics. More particularly, the present invention is directed to cloth-like, liquid-impervious, breathable film-nonwoven composite fabrics, comprising at least one nonwoven layer and a microporous film, having biological liquid barrier capabilities for use as, for example, sterilization wrap, surgical draping, surgical gowns, cover garments, such as over-suits, and the like.

Description

Improved cloth-like liquid impermeable breathable composite barrier fabric

field of invention

This invention relates to cloth-like liquid-impermeable and breathable composite barrier fabrics. In particular, the present invention is directed to cloth-like liquid-impermeable-breathable breathable membrane-nonwoven composite fabrics which have the ability to block biological fluids and are useful, for example, as antiseptic coats, surgical drapes, surgical pajamas, gowns, such as overcoats etc.

Background of the invention

Surgical gowns, surgical drapes, surgical masks, and antiseptic overcoats and antiseptic breakaway pockets (hereinafter collectively referred to as "surgical articles") must have a balance of properties, features, and performance characteristics in order to function satisfactorily. Such surgical articles are primarily designed to greatly reduce, if not prevent, the transmission of biological fluids and/or airborne contaminants through them. In the context of surgical procedures, such fluid sources include perspiration from the wearer of such pajamas, patient body fluids 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 dust, dust, skin flakes, 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, ie, wearing. The air permeability of a surgical article, ie its water vapor transmission rate, is an important measure of its comfort in use. Other characteristics of a surgical article that affect its comfort in use include, but are not limited to, its drapability, clothy feel, hand, cool and dry feel.

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

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

Liquid impermeable and breathable multilayer barrier fabrics using various constructions are known. Surgical articles formed from liquid-repellent fabrics, such as those formed from nonwoven fabrics or layers of yarn, have provided acceptable liquid impermeability, breathability, cloth-like drape, strength and durability, and low cost . However, there is still a need for improved cloth-like liquid-impermeable and breathable barrier materials for forming surgical articles and for other garments and gowns, such as personal protective equipment (such as work clothes), wherein some of the above-mentioned performance characteristics and characteristics Or all that is desired or necessary. Other applications for personal protective equipment include, but are not limited to, laboratory use, clean room use such as in semiconductor manufacturing, agricultural use, mining use, environmental use, and the like.

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

Summary of the invention

Accordingly, it is an object of the present invention to provide such an improved cloth-like liquid-impermeable-breathable barrier material which achieves a superior balance of performance characteristics and features suitable for use in garments, gowns and personal protective equipment, including For surgical products.

More specifically, it is a first object of the present invention to provide such an improved cloth-like liquid-impermeable-breathable-breathable barrier material which is effective in blocking the passage of biological fluids and which complies with the measurements required by ASTMES 21 test method.

It is a further object of the present invention to provide such an improved cloth-like liquid-impermeable-breathable-breathable barrier material which is very comfortable for the wearer when worn. The barrier materials of the present invention exhibit high levels of breathability, eg, 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 drapability, with a drape stiffness of <4.0 cm as measured by the test method described herein.

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

It is a further object of the present invention to provide such an improved cloth-like liquid-impermeable-breathable-breathable barrier material which is lightweight, relatively inexpensive to manufacture, and has a basis weight of less than about 2.0 oz/ ^yd2 .

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

Brief description of the drawings

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

Figure 2 schematically illustrates the process used to make 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 well-balanced set of performance characteristics and characteristics making it suitable for use as surgical articles, as well as for use as other garments and gowns, such as for personal protective gear. Embodiments of the barrier material of the present invention are explained with reference to the drawings. The barrier material 10 is a laminate comprising three layers: a nonwoven top layer 12, for example formed of spunbond fibers; a nonwoven bottom layer 16, for example formed of spunbond fibers; and a breathable middle layer 14, for example formed of a microporous film. The layers of barrier material 10 are bonded by known means, including thermo-mechanical bonding, ultrasonic bonding, adhesives, stitching, and the like. Laminated, glued or attached together.

"Layer" or "fabric" as used herein can have the dual meaning of a single piece or a plurality of pieces when it appears alone. As used herein, "laminate" means two or more layers of fabric materials that have been bonded or bonded to each other. As used herein, "nonwoven fabric" or "nonwoven fabric" means a fabric having an intertwined structure of individual fibers or filaments, but distinct and repeating structures other than knitted or woven fabrics. structure.

Commercially available thermoplastic polymeric materials may well be used to make the fibers or filaments from which the nonwoven topsheet 12 and bottomsheet 16 are formed. As used herein, "polymer" shall include, but is not limited to, homopolymers; copolymers such as block, graft, random and alternating copolymers; terpolymers, and the like, and mixtures and modifications thereof. Furthermore, unless specifically limited otherwise, "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" means a long chain polymer that softens when heated and returns to a solid state when cooled to room temperature. Typical thermoplastic materials include, but are not limited to, polyvinyl chloride, polyesters, polyimides, polyfluorocarbons, polyolefins, polyurethanes, polystyrene, polyvinyl alcohol, caprolactam, and copolymers thereof.

Nonwoven fabrics that can be used in the nonwoven layers 12 and 16 of the present invention can be formed by a variety of known forming methods including spunbond, airlaid, meltblown or bonded carded fabric forming methods. For example, in the illustrated embodiment of the invention, both top layer 12 and bottom layer 16 are spunbond nonwovens, which have proven advantageous in forming barrier material 10 . Spunbond nonwovens are made by melt spinning. As used herein, "melt spinning" refers to small diameter fibers and/or filaments formed by extruding molten thermoplastic material into filaments from the many small, usually circular capillaries of a spinneret, extruded The diameter of the filaments is then rapidly reduced using, for example, non-suction or suction fluid drawing or other known spunbonding mechanisms. Finally, the melt-spun filaments are deposited in a substantially random manner onto a moving carrier belt or similar device to form a web of substantially continuous and randomly arranged melt-spun filaments. Spunbond filaments are generally not bonded when they are deposited onto a gathering surface. The production of such spunbonded nonwovens has been described in U.S. Patent Nos. 4,340,563 (Appel et al.), No. 3,692,618 (Dorschner, etc.), No. 3,802,817 (Matsuki, etc.), No. 3,338,992 and No. 3,341,394 (Kinney), No. 3,502,538 (Peferson) and No. 3,542,615 (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, more specifically between about 10-100 microns. Another common use to express the diameter of a fiber or filament is denier which is defined as grams per 9000 meters of fiber or filament.

Spunbond fabrics are stabilized or cured (pre-bonded) in some manner immediately after they are produced so that the fabrics have sufficient integrity and strength to withstand the rigors of further processing into finished products. This pre-bonding step can be accomplished by applying a heat-activatable adhesive in liquid or powder form to the filaments, or more generally by means of pinch rollers. "Pinch rolls" as used herein means a set of rolls above or below a nonwoven fabric which are used to compress the fabric as a means of handling freshly produced melt-spun, especially spunbond, In order to make the fabric sufficiently integral for further processing, but not to allow subsequent secondary bonding treatments such as by air bonding, thermal bonding, ultrasonic bonding, etc. to produce a stronger bond. Compaction rolls squeeze the fabric slightly to enhance its self-adhesiveness and thus its integrity.

A typical secondary bonding process utilizes an embossing roll arrangement to thermally bond the spunbond fabric, typically comprising an embossing bonding roll and a smooth anvil roll which together define a thermal embossing bonding nip. Alternatively, the above-mentioned anvil roll may also carry a bonded pattern on its outer surface. The embossing roll is heated to a suitable bonding temperature by a conventional heating device and driven to rotate by a conventional driving device, so that a series of thermal patterns can be formed when the spunbonded fabric passes through the gap. The nip pressure in the nip should be sufficient to achieve the desired degree of bonding of the fabric given the line speed, bonding temperature, and material from which the fabric is formed. For such spunbond fabrics, the percent bond area is generally from about 10% to about 20%.

The breathable intermediate film layer 14 can be formed from any microporous film that can be properly bonded or attached to the top layer 12 and the bottom layer 16 to form a film that advantageously combines the performance characteristics and characteristics described herein. The barrier material 10 is enough. A suitable class of films comprises at least two essential components: a thermoplastic elastic polyolefin polymer and a filler. These components (and others) can be mixed together, heated and then extruded into a monolayer or multilayer film using any of a variety of film production methods well known to those in the film processing art. Such film-making processes include, for example, cast embossing, chill cast and flat cast, and blown film methods.

Generally, on a dry weight basis, the film layer 14 will comprise from about 30 to about 60 percent by weight of a thermoplastic polyolefin polymer or mixture thereof, and from about 40 to about 70 percent by weight of a thermoplastic polyolefin, based on the total weight of the film. filler. Other additives and ingredients may be added to 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 fillers in addition to the polyolefin polymer. "Filler" as used herein includes particulate and other forms of materials 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 will be in particulate form, which 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 scope of the present invention as long as they do not interfere with the film forming process or enable the film layer to function as required by the present invention. Suitable fillers include calcium carbonate (CaCO ₃ ), various clays, 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, can be applied to the filler particles.

As noted above, film layer 14 may be formed by any conventional method known to those skilled in the art of film formation. Polyolefin polymers and fillers are mixed in the ranges given above, then heated and extruded into films. In order to provide uniform breathability as reflected in 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. As far as the present invention is concerned, when calculated with the aforementioned test method, when its water vapor transmission rate is at least 300 g/m ² /24 hours (g/m ² /24hr), it is considered that the film layer is "breathable". Generally, the film layer will have a weight per unit area of less than about 80 grams per ^square meter (gsm) once formed and from about 10 to about 25 gsm after stretch thinning.

The film layer used in the examples of the invention described below is a single layer film, but other types of film layers such as multilayer films are also within the scope of the invention, as long as the forming technology can be matched with the film being filled That's it. This film is generally thick and unusually noisy in its initial formation, it tends to "click" when shaken. Furthermore, the as-formed film does not possess a sufficient degree of air permeability in terms of its water vapor transmission rate. To do this, the film is heated to a temperature equal to or about 5° below the melting point of the polyolefin polymer, and then the film is stretched to about 50% of its original length using a linear machine direction orientation (MDO) device. At least 2 times (2x) to thin the film and make it porous. This film layer 14 is further stretched to about 3 times (3x), 4 times (4x) or more multiples of its original length, and the original length of this film layer is obviously formed in connection with the film layer 14 of the present invention. Word.

The film layer 14 should have an "effective" film thickness or film thickness after stretch thinning of from about 0.2 to about 0.6 mils. This effective thickness is used to take into account voids or air gaps in the breathable film layer. For a typical unfilled gas impermeable membrane, the actual and effective thickness of the membrane are the same. However, for stretch-filled films, as mentioned earlier, the thickness of the film will include air gaps. In order to ignore the increased volume, the effective thickness can be calculated according to the test method listed below.

Referring to Figure 2, there is illustrated a process for the continuous preparation of the barrier material 10 of the present invention. Film layer 14 is formed using an optional type of conventional film forming equipment 20 such as cast film or blown film equipment. Film layer 14 having the formulation is then passed through film stretching apparatus 22 to stretch and thin the film to an effective thickness of 0.6 mils or less. A suitable type of film stretching equipment is a machine direction orientation unit, Model 7200, available from Marshall & Williams Company, having a place of business in Providence, Rhode Island.

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

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

As shown in Figure 2, the bonding roll 30 is an embossing roll, while the second bonding roll 32 is a smooth roll. Both rollers are driven by transmission means such as electric motors (not shown). The embossing roll 30 is a right cylinder and may be formed of any suitable durable material, such as steel, to reduce wear of the roll in use. The outermost surface of the embossing roll 30 has a pattern of raised bond areas. For example, an intermittent pattern of discrete, regularly repeating adhesive points may suitably be employed, as is usual in the art. The bonded area on the embossing roll 30 forms a nip with the smooth or flat outer surface of the opposed anvil roll 32, which is also a right cylinder and may be formed of any suitable durable material, such as steel, Formed from hardened rubber, resin-treated cotton or polyurethane.

The pattern of raised bonding areas on the embossing roll 30 is selected such that at least one surface of the resulting barrier material 10 is the area occupied by the adhesive after passing through the gap formed between the rolls 30, 32, for this purpose From about 10% to about 30% of the surface area of the barrier material. The bonded area of the barrier material 10 can be varied to achieve the above mentioned percent bonded areas, as is well known in the art.

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

Various modifications to the above can be readily suggested by those skilled in the art without departing from the spirit and scope of the invention. For example, after barrier material 10 is formed, it can continue on-line for further processing or transformation. Alternatively, different equipment can be used to stretch the film layer 14. Other known means for bonding and laminating the film layer 14 to the nonwoven layers 12, 16 may be used so long as the resulting barrier material 10 has the desired properties described above. Finally, the film layer 14 and/or the nonwoven layers 12, 16 can be formed remotely by unwinding the individual layers in a roll from a spool and feeding them into the nip formed between the embossing roll 30 and the smooth roll 32. . Also, in some applications, for example, one of the two spunbond fabrics can be advantageously omitted to 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 yard ² (osy), and generally from about 0.9 to 1.3 osy. Such materials can be laminated to stretch-thinned films by heating or bonding to form composites.

Having described certain embodiments of the invention, a series of sample barrier materials were tested to further illustrate the invention and to show those skilled in the art the manner in which it may be practiced. The results of measurements of certain physical properties of the barrier materials 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 5 measurements of various properties for each sample and comparative barrier material.

experiment method

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

Effective thickness

The effective thickness of the film is calculated by dividing the basis weight of the film from the density of the polymers and fillers forming the film. To obtain the effective thickness of the film in inches, multiply the measured weight per square yard (osy) by 0.001334 (metric-to-imperial unit conversion factor) and divide the result by grams The density of a polymer composition in units per centimeter ³ (g/cc).

Tensile strength and elongation test

The grab test for tensile strength and elongation measures the breaking load and percent elongation before breaking, the "stretchability" of a material. These measurements are made with the material under constant elongation under successively increasing loads in a single direction. The test process is strictly in accordance with ASTM standard D-5035-92 and D-5035-92 and INDA IST110.1-92, using constant velocity elongation testing machine such as Sintech system 2 computer integrated test system, developed by MTS in Eden Prairie, Minnesota Systems Inc. manufactures.

For each sample material, use a 4 inch (100 mm) wide precision knife to cut 5 test specimens, each 4 inches (100 mm) wide and 6 inches (150 mm) long, so that the direction of the long dimension is parallel to Tested and applied directions. The specimen is placed in the grips of the constant velocity tensile testing machine. Each specimen 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 is applied to the specimen with the crosshead speed (loading rate) set at 300 mm/min until the specimen breaks. Record the peak load, peak energy and peak strain as well as the average value. Record machine direction (MD) and cross-machine direction (CD) measurements separately.

water vapor transmission rate

According to ASTM standard E96-80, calculate the water vapor transmission rate (WVTR) of sample material, cut out the circular sample of 3 inches diameter from each test material and contrast material, this contrast material is a piece of CELGARD ²⁵⁰⁰ film, Available from Hoechst Celanese Corporation of Sommerville, New Jersey. The ^CELGARD® 2500 membrane is a microporous polypropylene membrane and three samples were prepared for each material. The test disc was a No. 60-1 Volatility Disc available from Thwing-Albert Instrument Company of Philadelphia, Pennsylvania. Pour 100 milliliters (me) of distilled water into each volatility meter pan, and simultaneously place each sample of both the sample material and the reference material across the open top of each pan, fasten the upper helical flange, and The edges formed a seal (no sealing paste was used) and the associated test or control material was exposed to ambient atmosphere up to a 6.5 cm diameter circle with an exposed area of approximately 33.17 ^cm2 . The pans were weighed and then placed in a forced air oven at a temperature of 37°C. The furnace is a constant temperature furnace through which outside air is circulated to prevent water vapor from collecting inside. A suitable forced air oven is, for example, the Blue M Power-O-Matic 60 oven, available 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 value for this preliminary test is calculated as follows:

Test WVTR (g/ ^m2 /24 hours) = (gram weight loss after 24 hours) x 315.5 g/ ^m2 /24 hours The relative humidity in the furnace is not specifically controlled.

Under preset conditions of 100°F (32°C) and ambient relative humidity, the WVTR of ^CELGARD® 2500 film has been determined to be 5000 grams per square meter ^per 24 hours (g/ ^m2 /24hr). In this way, each test is carried out on the comparative sample, and the preliminary test value is corrected relative to the set conditions by applying the following formula:

WVTR (g/ ^m2 /24 hours) = (test WVTR/comparative WVTR) × 500 g/ ^m2 /24 hours

base weigh

The basis weight of the sample material is determined in accordance with Federal Test Method No. 191A/5041. The sample size of the sample material was 15.24 cm x 15.24 cm, and 5 values were obtained for each material and then averaged.

hydrostatic pressure test

The hydrostatic pressure test measures a nonwoven's resistance to penetration of water under low hydrostatic pressure. The test procedure was based on Method 5514-Federal Test Method Standard No. 191A, AATCC Test Method 127-89, and ZNDA Test Method 80.4-92, modified to include window supports with standard synthetic fiber screen materials.

A Textest FX-300 hydrostatic head tester, available from Schmid Corp, having a place of business in Spartanburg, South Carolina, has its test head filled with purified water. This purified water is maintained at a temperature of 65°F-85°F (18.3°C-29.4°C), which is within the range of standard ambient conditions (approximately 73°F (23°C) and approximately 50% relative humidity). For testing, an 8 inch by 8 inch (20.3 cm by 20.3 cm) square specimen of test material is placed to completely cover the reservoir of the test head. The sample is under standard water pressure and the water pressure is increased at a constant rate until leakage is observed on the outer surface of the sample material. The hydrostatic resistance was measured at the first sign of a leak in three separate areas of the test specimen. This test was repeated on 5 samples of each sample material. The hydrostatic resistance obtained for each sample was averaged and the result reported in millibars. Higher value surfaces have greater resistance to fluid penetration.

cup crush test

The cup crush test is based on a constant velocity elongation tensile tester that uses peak load and energy units to measure the softness of a material. The lower the peak load value, the softer the material.

The test procedure was conducted in a controlled environment with a temperature of about 73°F (23°C) and a relative humidity of about 50%. The sample was carried out with the aforementioned Sintech System 2 computer-integrated test system, and the crushing test bench was purchased from Kimberly-Clark Corp Quality Assurance Department in Neenah, Wisconsin. This test bench includes a model 11 bracket, a model 31 steel ring, a base plate , Type 41 cup assembly and calibration device.

The steel ring is placed on the forming cylinder and a 9 inch by 9 inch (22.9 cm by 22.9 cm) specimen is centered over the forming cylinder. Slide the forming cup over the forming cylinder until the specimen is completely sandwiched between the forming cylinder and the steel ring around the steel ring. The forming cup is placed on top of the substrate in the load chamber and sits firmly on the back of the substrate. Set the crosshead speed at 400 mm/min, lower the support into the forming cup mechanically, crush the sample, and measure the peak load required to crush the sample by the constant velocity elongation tensile tester (in grams) and energy (in grams.mm). The average of the peak loads and energies for five specimens was calculated for each specimen material and reported here.

Suspension Stiffness Test

The drape stiffness test uses the cantilever bending principle of the fabric under its self-sag to determine the bending length of the fabric. This test method measures the resistance of a fabric to bending by drape stiffness. The bend length is a measure of the interaction between the weight of the fabric and the stiffness of the fabric represented by the fabric as it bends from its sag. It reflects the stiffness of the fabric bending in a plane under gravity.

A 1 inch by 8 inch (2.54 cm by 20.32 cm) specimen is slid at a speed of 4.75 in/min (12.07 cm/min) parallel to its long dimension so that its front edge protrudes from the edge of the horizontal surface. When the tip of the sample is pressed down under the self-weight of the sample until the line connecting the tip to the edge of the test bench forms an angle of 41.5° with the horizontal plane, measure the length of the protruding part. The longer the extension, the slower the fabric bends, so a higher value indicates a stiffer fabric.

This test procedure is in accordance with ASTM standard test D1388, except that the dimensions of the specimens are as described above. The MD and CD measurements of the bend length were made and recorded separately using a cantilever bend tester such as the Model 79-10 available from Test Machine Company having offices in Amityville, New York.

The suspension stiffness is calculated as follows:

Drape Stiffness (cm) = Bending Length (inches) x 2.54 The average value of the sag stiffness is reported here.

example

Sample 1

Barrier materials of the present invention were prepared. The film layer, based on its total weight percentage, contains: 13% Shell 6D82 polypropylene/polyethylene copolymer containing 5.5% ethylene; 18% Rexene FD-D1700 low crystallinity polypropylene, which has high Atactic stereoisomers of molecular weight polymer chains; 3% Dow5004 with 60000ppm Irgafos168 used as antioxidant and stabilizer; 2% SCC12673 blue concentrate available from Stondridge ColorCorp.; and 64% English China Supercoat Calcium Carbonate (CaCO ₃ ), coated with 1.5% behenic acid, has an average particle size of 1 micron and a top cut of 7 microns. This calcium carbonate was purchased from ECCA Calcium Products, Inc, in Sylacauga, Alabama, a division of ECC International. The above-mentioned film material is blown into a single-layer film.

The aforementioned top and bottom spunbond layers are both 0.6 oz/ ^yd2 nonwoven fabrics formed from an extrudable thermoplastic resin comprising: 97% Shell of propylene and ethylene monomer containing 3% ethylene 6D43 random copolymer; 2% titanium dioxide (white); 0.09% antistatic compound and 0.91 SCC11111 blue concentrate. The spunbond filaments are substantially continuous in nature and have an average fiber size of 2.0 dpf.

The above film and the top and bottom nonwoven layers were laminated together with thermally bonded rolls as previously described. The bond temperature for the embossed roll is about 185°F and the temperature for the smooth anvil roll is about 145°F. The nip pressure developed between the two rolls was about 440 psig.

Comparative example 2

Trial 3 Commercially available Baxter Vira Block surgical gown.

Comparative example 3

Trial 3 Commercially available 3M surgical gown with Prevention fabric.

Comparative example 4

Trial 3 Commercially available Baxter Optima standard surgical gown.

Comparative Example 5

Test 3 is commercially available as the Evolution3 standard surgical gown from Kimberly-Clark Corp.

All measurements shown in the following two tables were taken from the body portions of various surgical gowns. All values shown are based on the average of 5 measurements. Table 1 sample Basis weight (osy) MD Peak Load (lb) Grab sample peak energy (in-lb) Tensile peak strain (%) CD Peak Load (lb) Grab sample 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 sample Fluid pressure head (mbar) WVTR(g/m ² /24hr) Cup energy (g/mm) Breaking load (g) Hanging stiffness (MD) (cm) Hanging 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 demonstrate that the barrier material 10 of the present invention has an excellent combination of low basis weight, good strength and durability, barrier properties, breathability, and textile-like drape and softness and physical characteristics. characteristic.

It will be appreciated that the improved cloth-like liquid-impermeable-breathable-breathable barrier material constructed in accordance with the present invention is modifiable by those skilled in the art to accommodate various degrees of performance in practice. Therefore, while the invention has been described above with reference to certain specific embodiments and examples, it should be understood that the invention is capable of other various configurations. Therefore, this application is intended to cover any variation, use or modification of the present invention under its general principles, and is intended to include, although departing from the content disclosed in this application, which is involved in the present invention and belongs to the appended claims. Known or usual technical practice within the scope of the requirement.

Claims (23)

1. A cloth-like liquid-impermeable-breathable barrier material comprising: at least one nonwoven layer; A microporous film layer bonded to the above nonwoven layer to form a laminate which is breathable, has a WUTR measuring at least 300 gm/ ^m2 /24hr and has a basis weight of about 2.0 oz/yd ² or less, peak energy in the machine direction of at least 15 inches a pound, peak strain in the machine direction of at least about 35 percent, peak energy in the cross-machine direction of at least about 19 inches a pound, and peak strain in the machine direction of at least about 70 percent , a hydrostatic head of about 250 millibars (mbar) or greater, a cup crush peak load of less than about 180 grams, a cup compression energy of less than about 3000 g/mm, a hang stiffness of <4.0 cm in the machine direction, and a cross-cut Machine direction overhang stiffness < 3.0 cm. 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-breathable barrier material of claim 1, wherein the film layer is a monolayer film. 6. The cloth-like liquid-impermeable-breathable-breathable barrier material of claim 1, wherein the film layer is a multilayer film. 7. The cloth-like liquid-impermeable-breathable-breathable barrier material of claim 1, wherein said laminate has a water vapor transmission rate of at least 1000 g/ ^m2 /24 hours. 8. The cloth-like liquid-impermeable-breathable-breathable barrier material of claim 1, wherein said laminate has a water vapor transmission rate of at least 3000 g/ ^m2 /24 hours. 9. The cloth-like liquid-impermeable-breathable-breathable barrier material of claim 1 , wherein the nonwoven layer comprises about 98% random copolymer of both polypropylene and polyethylene having a 3% ethylene content. 10. The cloth-like liquid-impermeable-breathable-breathable barrier material of claim 1 , wherein said film layer comprises about 40 to about 70 percent by weight of its own total weight of filler and about 30 to about 60% polyolefin polymer, or their mixture. 11. The cloth-like liquid-impermeable-breathable-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-breathable barrier material of claim 1. 17. A surgical breakaway garment bag comprising the cloth-like liquid-impermeable-breathable-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-breathable barrier material of claim 1 comprising a thermoplastic elastic polyolefin. 21. The cloth-like liquid-impermeable-breathable-breathable barrier material of claim 11 comprising a thermoplastic elastic polyolefin. 22. A personal article comprising the cloth-like liquid-impermeable-breathable barrier material of claim 1. 23. A personal article comprising the cloth-like, liquid-impermeable, breathable barrier material of claim 11.