Patent Application
20190150534
The present invention relates to a collar for protective garments such as disposable surgical gowns worn by medical care providers in the operating room or people in any other environment where exposure to hazardous materials and liquids is a risk.
Surgeons and other healthcare providers often wear an over garment during operating procedures in order to enhance the sterile condition in the operating room and to protect the wearer. The over garment is typically a gown that has a main body portion to which sleeves and a tie cord, hook and loop closures, or other securing means are attached. While fastening means such as the aforementioned hook and loop materials can be used in conjunction with or in place of tie cords, other personal protective equipment such as a bouffant cap can become caught in the hook and loop materials based on their placement, which can be very irritating to the wearer. Moreover, in order to ensure that no blood, bone fragments, or other biologic materials or body fluids come into contact with the wearer, the neck opening or collar of many surgical garments can be tight, restrictive, and uncomfortable to the wearer. The hook and loop closures can be located at the back of the over garment near its proximal end towards a neck opening or collar and help secure the over garment about the wearer. In order to prevent the spread of infection to and from the patient, such neck openings or collars are generally form-fitting, tight, and restrictive so that bodily fluids and other liquids present during surgical procedures are kept from flowing through the gown. For instance, in many embodiments, the neck opening includes a collar that has a scoop-necked design where the gown fabric is covered with a small strip of a spunbond nonwoven material. This material can rub against the sensitive neck area and can also cause the gown to gap open as the wearer leans forward during a surgical procedure, which exposes the wearer to bone fragments, blood, and other biologic materials.
Further, gowns made from an impervious material provide a high degree of protection, but a surgical gown constructed of this type of material is typically heavy, restrictive, expensive, and uncomfortably hot to the wearer. While efforts have been made to utilize a lighter weight material in order to provide for better breathability and help reduce the overall weight of the gown, the higher the breathability of the material, the lower the repellency of the material, where the material may not meet the minimum guidelines that have been created for the rating of the imperviousness of surgical gowns, gloves and the like.
Specifically, the Association for the Advancement of Medical Instrumentation (AAMI) has proposed a uniform classification system for gowns and drapes based on their liquid barrier performance. These procedures were adopted by the American National Standards Institute (ANSI) and were recently published as ANSIA/AAMI PB70: 2012 entitled Liquid Barrier Performance and Classification of Protective Apparel and Drapes Intended for Use in Health Care Facilities, which was formally recognized by the U.S. Food and Drug Administration in October, 2004. This standard established four levels of barrier protection for surgical gowns and drapes. The requirements for the design and construction of surgical gowns are based on the anticipated location and degree of liquid contact, given the expected conditions of use of the gowns. The highest level of imperviousness is AAMI level 4, used in “critical zones” where exposure to blood or other bodily fluids is most likely and voluminous. The AAMI standards define “critical zones” as the front of the gown (chest), including the tie cord/securing means attachment area, and the sleeves and sleeve seam area up to about 2 inches (5 cm) above the elbow.
In light of the above, a need exists for a surgical garment (e.g., a surgical gown) that meets the AAMI level 4 standard while at the same time being stretchable, soft, breathable, and cool to maximize the comfort for the wearer (e.g., medical care providers) with a collar that is not restrictive or uncomfortable. Further, a need exists for a collar that can prevent gapping at the neck opening of the surgical garment, which can put the wearer at risk of exposure to blood, bone fragments, or other biologic materials. A need also exists for a collar configuration that permits the use of fastening means that maintain such a garment securely in place during use but that does not result in other personal protective equipment (e.g., a bouffant) becoming attached or caught in the fastening means.
In accordance with one embodiment of the present invention, a collar for a disposable surgical gown is provided. The collar includes a first portion having a first end and a second end and a second portion having a first end and a second end. The first end of the first portion and the first end of the second portion meet at a front of the collar to form a v-neck shape and the second end of the first portion and the second end of the second portion meet at a rear of the collar to define a neck opening. The v-neck shape at the front of the collar forms an angle of greater than 90° at the neck opening, and wherein the second end of the first portion and the second end of the second portion are tapered.
In one particular embodiment, the first end of the first portion can overlap the first end of the second portion to form the v-neck shape.
In another embodiment, the first end of the second portion can overlap the first end of the first portion to form the v-neck shape.
In still another embodiment, the v-neck shape can form an angle ranging from about 95° to about 140° at the neck opening.
In yet another embodiment, the first end of the first portion and the first end of the second portion of the collar can each have a height ranging from about 10 millimeters to about 75 millimeters.
In an additional embodiment, the second end of the first portion and the second end of the second portion of the collar can each include a tapered section having a height ranging from about 1 millimeter to about 9 millimeters. Further, the ratio of the height of the collar at tapered sections to the height of the collar at the first end of the first portion and the first end of the second portion can range from about 1:2 to about 1:50.
In one more embodiment, the collar can be formed from an extensible material.
In one particular embodiment, the collar can be formed from a knit material.
In another embodiment, the collar can include a polyester.
In still another embodiment, the collar can be air breathable, wherein the collar has an air permeability ranging from about 100 ft3/ft2/minute to about 370 ft3/ft2/minute.
In yet another embodiment, the collar can be liquid resistant.
In an additional embodiment, the collar can lay flat against a wearer during movement by the wearer when the collar is attached to a disposable surgical gown.
In accordance with another embodiment of the present invention, a disposable surgical gown is provided. The gown includes a front panel, a first sleeve, and a second sleeve, wherein the front panel, the first sleeve, and the second sleeve each comprise an outer spunbond layer having a surface that defines an outer-facing surface of the front panel, a spunbond-meltblown-spunbond (SMS) laminate having a surface that defines a body-facing surface of the front panel, and a liquid impervious, moisture vapor breathable elastic film disposed therebetween; a first rear panel and a second rear panel, wherein the first rear panel and the second rear panel are formed from a nonwoven laminate that is air breathable; and a collar, wherein the collar comprises a first portion having a first end and a second end and a second portion having a first end and a second end, wherein the first end of the first portion and the first end of the second portion meet at a front of the collar to form a v-neck shape and the second end of the first portion and the second end of the second portion meet at a rear of the collar to define a neck opening, wherein the v-neck shape at the front of the collar forms an angle of greater than 90° at the neck opening, and wherein the second end of the first portion and the second end of the second portion are tapered.
In one particular embodiment, the first end of the first portion of the collar can overlap the first end of the second portion of the collar to form the v-neck shape.
In another embodiment, the first end of the second portion can overlap the first end of the first portion to form the v-neck shape.
In still another embodiment, the v-neck shape can form an angle ranging from about 95° to about 140° at the neck opening.
In yet another embodiment, the first end of the first portion and the first end of the second portion of the collar can each have a height ranging from about 10 millimeters to about 75 millimeters.
In an additional embodiment, the second end of the first portion and the second end of the second portion of the collar can each include a tapered section having a height ranging from about 1 millimeter to about 9 millimeters.
In one more embodiment, the ratio of the height of the collar at tapered sections to the height of the collar at the first end of the first portion and the first end of the second portion can range from about 1:2 to about 1:50.
In one particular embodiment, the collar can be formed from an extensible material.
In another embodiment, the collar can be formed from a knit material.
In still another embodiment, the collar can include a polyester.
In yet another embodiment, the collar can be air breathable.
In an additional embodiment, the collar can be liquid resistant.
In one more embodiment, the collar can lay flat against a wearer during movement by the wearer.
In accordance with another embodiment of the present invention, a method for forming a collar on a disposable surgical gown is provided. The method includes providing a first collar portion having a first end, a second end and a lower edge; attaching the first collar portion along its attachment side to a disposable gown to form a first section of a collar; providing a second collar portion having a first end, a second end and a lower edge; and attaching the second collar portion along its lower edge to a disposable gown to form a second section of a collar such that the first end of the first portion and the first end of the second portion meet at a front of the collar to form a v-neck shape and the second end of the first portion and the second end of the second portion meet at a rear of the collar to define a neck opening, wherein the v-neck shape at the front of the collar forms an angle of greater than 90° at the neck opening, and wherein the second end of the first portion and the second end of the second portion are tapered.
In one embodiment, the disposable gown has a front panel, a first sleeve, a second sleeve, a first rear panel, and a second rear panel, wherein the first collar portion is attached to the front panel, first sleeve, and first rear panel, and wherein the second collar portion is attached to the front panel, second sleeve, and second rear panel.
In another embodiment, the first collar portion and the second collar portion are attached to the disposable gown by sewing or ultrasonic bonding.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention to one skilled in the art, including the best mode thereof, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.
As used herein, the term “spunbond” refers to fabric made from small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine, usually circular capillaries of a spinneret with the diameter of the extruded filaments then being rapidly reduced as by, for example, in U.S. Pat. No. 4,340,563 to Appel, et al., U.S. Pat. No. 3,692,618 to Dorschner, et at, U.S. Pat. No. 3,802,817 to Matsuki, et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, and U.S. Pat. No. 3,542,615 to Dobo, et al. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface. Spunbond fibers are generally continuous and have average diameters (from a sample of at least 10) larger than 7 microns, more particularly, between about 10 and 20 microns.
As used herein, the term “meltblown” refers to fabric formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. The meltblown fibers are then carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin et al. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are generally tacky when deposited onto a collecting surface.
As used herein, the term “SMS laminate” refers to fabric laminates of spunbond and meltblown fabrics, e.g., spunbond/meltblown/spunbond laminates as disclosed in U.S. Pat. No. 4,041,203 to Brock et al., U.S. Pat. No. 5,169,706 to Collier, et al, U.S. Pat. No. 5,145,727 to Potts et al., U.S. Pat. No. 5,178,931 to Perkins et al. and U.S. Pat. No. 5,188,885 to Timmons et al. Such a 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 below. Alternatively, the fabric layers may be made individually, collected in rolls, and combined in a separate bonding step. Such fabrics usually have a basis weight of from about 0.1 osy to 12 osy (about 3.4 gsm to about 406 gsm), or more particularly from about 0.75 to about 3 osy (about 25.4 gsm to about 101.7 gsm).
Reference now will be made in detail to various embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Generally speaking, the present invention is directed to a collar for a disposable protective garment (e.g., a surgical gown), where the gown meets the AAMI level 4 critical zone requirements while at the same time being comfortable to the wearer in terms of temperature, stretchability, fit, etc. The collar for the disposable surgical gown is formed from an extensible material that can be positioned adjacent a proximal end of the disposable surgical gown. Because of the extensibility of the material, the collar does not gap when the wearer moves, which could potentially expose the wearer to harmful biologic contaminants such as bone fragments or blood. Further, the front of the collar defines a neck opening having a v-neck shape adjacent the front panel. The v-neck shape of the collar forms an angle of greater than 90° at the neck opening. Such a v-neck shape allows the collar to lay flat against the wearer's chest and not gap open, thus protecting the wearer from contact with bone fragments and blood that may enter the neck opening of a surgical gown and contact the wearer's skin or scrubs. In addition, the back of the collar is tapered at the area where the gown is secured with fastening means (e.g., hook and loop fastening means) so that the collar material does not interfere with the fastening means used to secure the surgical gown about the wearer. The tapering also prevents the collar from becoming caught in other personal protective equipment such as a bouffant cap.
The gown onto which the collar is attached or sewn includes a front panel and sleeves that can be formed from a first material that includes a first spunbond layer, a spunbond-meltblown-spunbond laminate, and a liquid impervious, moisture vapor breathable elastic film disposed therebetween. The gown also includes first and second rear panels formed from a second material that is a nonwoven laminate, where the nonwoven laminate is air breathable and allows for an air volumetric flow rate ranging from about 20 standard cubic feet per minute (scfm) to about 80 scfm. The combination of features results in a gown that is stretchable and impervious to liquids, yet can still dissipate heat and humidity.
In addition, a specific combination of additives, pigments, and fillers can be included in the various layers of aforementioned first and second materials, where the combination of additives, pigments, and fillers increases the opacity (e.g., reduces glare) and reduces the light transmittance of the materials. Without intending to be limited by any particular theory, it is believed that this is due to the combination of high levels of light scattering and light absorption of the materials due to the incorporation of the various additives, pigments, and fillers in one or more layers of the materials, where the different refractive indices of the additives, pigments, and fillers in the various layers of the first and second materials enhance the ability of the materials to attenuate light by absorption and scattering, thus reducing glare when used in an operating room setting. For instance, the material used to form the disposable surgical gown of the present invention can have an opacity (diffuse reflectance using C-illuminant) greater than about 98%, such as from about 98% to about 99.9%, such as from about 98.25% to about 99.8%, such as from about 98.5% to about 99.7%. Further, the material used to form the disposable surgical gown of the present invention can have an absorption power of greater than about 0.85, such as from about 0.86 to about 1.2, such as from about 0.87 to about 1.15, such as from about 0.88 to about 1.1. In addition, the material used to form the disposable surgical gown of the present invention can have a transmittance of less than about 0.15, such as from about 0.05 to about 0.14, such as 0.06 to about 0.13, such as from about 0.07 to about 0.11.
Referring now to the front 158 of the gown 100,
Turning now to the rear 160 of the gown 100,
The various components of the protective garment are discussed in more detail below. As an initial matter, it is to be understood that any of the spunbond layers, meltblown layers, or elastic film layers of the first material 200 and/or the second material 300 can include pigments to impart the gown 100 with a gray color, which provides anti-glare and light reflectance properties, which, in turn, can provide a better visual field during surgeries or other procedures where operating room lighting can result in poor visual conditions, resulting in glare that causes visual discomfort, and leads to fatigue of operating room staff during surgical procedures.
For instance, examples of suitable pigments used to arrive at the desired gray pigment for the gown include, but are not limited to, titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites, kaolin, mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and combinations thereof. In certain cases, for instance, each of the various individual layers of the gown materials 200 and 300 can include titanium dioxide in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The titanium dioxide can have a refractive index ranging from about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from about 2.6 to about 2.8, such as about 2.76, to impart the material 200 with the desired light scattering and light absorbing properties. Further, each of the various individual layers of the gown materials 200 and 300 can also include carbon black in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The carbon black can have a refractive index ranging from about 1.2 to about 2.4, such as from about 1.4 to about 2.2, such as from about 1.6 to about 2 to impart the material 200 with the desired light scattering and light absorbing properties. Each of the various individual layers of the gown materials 200 and 300 can also include a blue pigment in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The combination of the carbon black and blue pigment improves the ability of the nonwoven materials and film of the present invention to absorb light.
As a result of the incorporation of one or more of the aforementioned pigments into the gown materials, the first material 200 and/or the second material 300 can thus be a sufficient shade of gray to prevent glare. Gray is an imperfect absorption of the light or a mixture of black and white, where it is to be understood that although black, white, and gray are sometimes described as achromatic or hueless colors, a color may be referred to as “black” if it absorbs all frequencies of light. That is, an object that absorbs all wavelengths of light that strike it so that no parts of the spectrum are reflected is considered to be black. Black is darker than any color on the color wheel or spectrum. In contrast, white is lighter than any color on the color wheel or spectrum. If an object reflects all wavelengths of light equally, that object is considered to be white.
As mentioned above, the front panel 102, sleeves 104, and front fastening means 116 of the gown 100 can be formed from a first material 200. The first material 200 can be a stretchable elastic breathable barrier material that renders the aforementioned sections of the gown 100 impervious to bodily fluids and other liquids while still providing satisfactory levels of moisture vapor breathability and/or moisture vapor transmission and stretchability. The first material 200 can include a combination of a film, which can serve as the key barrier and elastic component of the surgical gown 100, and one or more nonwoven layers (e.g., spunbond layers, meltblown layers, a combination thereof, etc) to provide softness and comfort. The film can be configured to exhibit elastic properties such that the film maintains its fluid barrier characteristics even when elongated in the machine direction by amounts at least as twice as high as currently available gowns such that the gown 100 passes ASTM-1671 “Standard Test Method for Resistance of Materials Used in Protective Clothing to Penetration by Blood-Borne Pathogens Using Phi-X174 Bacteriophage Penetration as a Test System.” Meanwhile, as a result of the inclusion of the nonwoven layers in conjunction with the elastic film, the overall first material 200 can have an increased bending modulus to achieve the desired pliability and softness which results in a material that is comfortable to the wearer.
As discussed above, in one particular embodiment, the first material 200 can include an outer spunbond layer 142, a spunbond-meltblown-spunbond laminate 146, and an elastic film 144 positioned therebetween. The outer spunbond layer 142 can form an outer-facing surface 202 of the front panel 102, sleeves 104, and front fastening means 116 of the surgical gown 100, while one of the spunbond layers of the SMS laminate 146 can form the body-facing surface or inner-facing surface 204 of the front panel 102 and sleeves 104 of the surgical gown 100. Meanwhile, the inner-facing surface of the front fastening means 116 can include a tape material for added barrier protection. Further, the outer spunbond layer 142 and one or more layers of the SMS laminate 146 can include a slip additive to achieve the desired softness, while the film 144 can include a fluorochemical additive to increase the surface energy of the elastic film 144 and enhance the ability of the elastic film 144 to serve as a barrier to bodily fluids and tissues, including fatty oils that may be generated during very invasive surgeries as a result of the maceration of fatty tissue. Each of these components of the first material 200 is described in more detail below.
A. Outer Spunbond Layer
The outer spunbond layer 142 can be formed from any suitable polymer that provides softness, stretch, and pliability to the first material 200. For instance, the outer spunbond layer 142 can be formed from a semi-crystalline polyolefin. Exemplary polyolefins may include, for instance, polyethylene, polypropylene, blends and copolymers thereof. In one particular embodiment, a polyethylene is employed that is a copolymer of ethylene and an α-olefin, such as a C3-C20 α-olefin or C3-C12 α-olefin. Suitable α-olefins may be linear or branched (e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired α-olefin co-monomers are 1-butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be from about 60 mole % to about 99 mole %, in some embodiments from about 80 mole % to about 98.5 mole %, and in some embodiments, from about 87 mole % to about 97.5 mole %. The α-olefin content may likewise range from about 1 mole % to about 40 mole %, in some embodiments from about 1.5 mole % to about 15 mole %, and in some embodiments, from about 2.5 mole % to about 13 mole %.
The density of the polyethylene may vary depending on the type of polymer employed, but generally ranges from 0.85 to 0.96 grams per cubic centimeter (“g/cm3”). Polyethylene “plastomers”, for instance, may have a density in the range of from 0.85 to 0.91 g/cm3. Likewise, “linear low density polyethylene” (“LLDPE”) may have a density in the range of from 0.91 to 0.940 g/cm3; “low density polyethylene” (“LDPE”) may have a density in the range of from 0.910 to 0.940 g/cm3; and “high density polyethylene” (“HDPE”) may have density in the range of from 0.940 to 0.960 g/cm3. Densities may be measured in accordance with ASTM 1505. Particularly suitable ethylene-based polymers for use in the present invention may be available under the designation EXACT™ from ExxonMobil Chemical Company of Houston, Tex. Other suitable polyethylene plastomers are available under the designation ENGAGE™ and AFFINITY™ from Dow Chemical Company of Midland, Mich. Still other suitable ethylene polymers are available from The Dow Chemical Company under the designations DOWLEX™ (LLDPE) and ATTANE™ (ULDPE). Other suitable ethylene polymers are described in U.S. Pat. No. 4,937,299 to Ewen et al.; U.S. Pat. No. 5,218,071 to Tsutsui et al.; U.S. Pat. No. 5,272,236 to Lai et al.; and U.S. Pat. No. 5,278,272 to Lai, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Of course, the outer spunbond layer 142 of the first material 200 is by no means limited to ethylene polymers. For instance, propylene polymers may also be suitable for use as a semi-crystalline polyolefin. Suitable propylene polymers may include, for instance, polypropylene homopolymers, as well as copolymers or terpolymers of propylene with an α-olefin (e.g., C3-C20) comonomer, such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer content of the propylene polymer may be about 35 wt. % or less, in some embodiments from about 1 wt. % to about 20 wt. %, in some embodiments, from about 2 wt. % to about 15 wt. %, and in some embodiments from about 3 wt. % to about 10 wt. %. The density of the polypropylene (e.g., propylene/α-olefin copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.91 g/cm3. In one particular embodiment, the outer spunbond layer 142 can include a copolymer of polypropylene and polyethylene. The polypropylene can have a refractive index ranging from about 1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50, such as about 1.49, while the polyethylene can have a refractive index ranging from about 1.46 to about 1.56, such as from about 1.48 to about 1.54, such as from about 1.50 to about 1.52, such as about 1.51, to impart the material 200 with the desired light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the designations VISTAMAXX™ from ExxonMobil Chemical Co. of Houston, Tex; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMER™ available from Mitsui Petrochemical Industries; and VERSIFY™ available from Dow Chemical Co. of Midland, Mich. Other examples of suitable propylene polymers are described in U.S. Pat. Nos. 6,500,563 to Datta, et al.; 5,539,056 to Yang, et al.; and 5,596,052 to Resconi, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Any of a variety of known techniques may generally be employed to form the polyolefins. For instance, olefin polymers may be formed using a free radical or a coordination catalyst (e.g., Ziegler-Natta or metallocene). Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. Nos. 5,571,619 to McAlpin, et at; 5,322,728 to Davis, et al.; 5,472,775 to Obijeski, et al.; 5,272,236 to Lai, et al.; and 6,090,325 to Wheat, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
The melt flow index (MI) of the polyolefins may generally vary, but is typically in the range of about 0.1 grams per 10 minutes to about 100 grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes, determined at 190° C. The melt flow index is the weight of the polymer (in grams) that may be forced through an extrusion rheometer orifice (0.0825-inch diameter) when subjected to a force of 2160 grams in 10 minutes at 190° C., and may be determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin, the outer spunbond layer 142 can also include a slip additive to enhance the softness of the outer spunbond layer 142. The slip additive can also reduce the coefficient of friction and increase the hydrohead of the outer spunbond layer 142 of the front panel 102 and the sleeves 104. Such a reduction in the coefficient of friction lessens the chance of the gown 100 being cut or damaged due to abrasions and also prevents fluids from seeping through the first material 200. Instead, at least in part due to the inclusion of the slip additive, fluid that contacts the outer-facing surface 202 of the gown 100 can remain in droplet form and run vertically to the distal end 156 of the gown 100 and onto the floor. The slip additive can also reduce the glare of the first material 200 in the operating room by reducing the light reflectance of the first material and can also render the first material 200 more opaque than the standard gown material when contacted with fats and lipids during surgery, where the standard gown material turns transparent upon contact with fats and lipids, which can result in the wearer having some concern that the barrier properties of a standard gown have been compromised.
The slip additive can function by migrating to the surface of the polymer used to form the outer spunbond layer 142, where it can provide a coating that reduces the coefficient of friction of the outer-facing surface 202 of the first material 200. Variants of fatty acids can be used as slip additives. For example, the slip additive can be erucamide, oleamide, stearamide, behenamide, oleyl palmitamide, stearyl erucamide, ethylene bis-oleamide, N,N′-Ethylene Bis(Stearamide) (EBS), or a combination thereof. Further, the slip additive have a refractive index ranging from about 1.42 to about 1.52, such as from about 1.44 to about 1.50, such as from about 1.46 to about 1.48, such as about 1.47, to impart the material 200 with the desired light scattering and light absorbing properties by reducing the refractive index. The slip additive can be present in the outer spunbond layer 142 in an amount ranging from about 0.1 wt. % to about 4 wt. %, such as from about 0.25 wt. % to about 3 wt. %, such as from about 0.5 wt. % to about 2 wt. % based on the total weight of the outer spunbond layer 142. In one particular embodiment, the slip additive can be present in an amount of about 1 wt. % based on the total weight of the outer spunbond layer 142.
In addition to the polyolefin and slip additive, the outer spunbond layer 142 can also include one or more pigments to help achieve the desired gray color of the gown 100. Examples of suitable pigments include, but are not limited to, titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites, kaolin, mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and combinations thereof. In certain cases, for instance, the outer spunbond layer 142 can include titanium dioxide in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the outer spunbond layer 142. The titanium dioxide can have a refractive index ranging from about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from about 2.6 to about 2.8, such as about 2.76, to impart the material 200 with the desired light scattering and light absorbing properties. Further, the outer spunbond layer 142 can also include carbon black in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the outer spunbond layer 142. The carbon black can have a refractive index ranging from about 1.2 to about 2.4, such as from about 1.4 to about 2.2, such as from about 1.6 to about 2 to impart the material 200 with the desired light scattering and light absorbing properties. The outer spunbond layer 142 can also include a blue pigment in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The combination of the carbon black and blue pigment improves the ability of the outer spunbond layer 142 to absorb light.
Regardless of the specific polymer or polymers and additives used to form the outer spunbond layer 142, the outer spunbond layer 142 can have a basis weight ranging from about 5 gsm to about 50 gsm, such as from about 10 gsm to about 40 gsm, such as from about 15 gsm to about 30 gsm. In one particular embodiment, the outer spunbond layer 142 can have a basis weight of about 20 gsm (about 0.6 osy).
B. Elastic Film
The elastic film 144 of the first material 200 can be formed from any suitable polymer or polymers that are capable of acting as a barrier component in that it is generally impervious, while at the same time providing moisture vapor breathability to the first material 200. The elastic film 144 can be formed from one or more layers of polymers that are melt-processable, i.e., thermoplastic. In one particular embodiment, the elastic film 144 can be a monolayer film. If the film is a monolayer, any of the polymers discussed below in can be used to form the monolayer. In other embodiments, the elastic film 144 can include two, three, four, five, six, or seven layers, where each of the layers can be formed from any of the polymers discussed below, where the one or more layers are formed from the same or different materials. For instance, in one particular embodiment the elastic film 144 can include a core layer 144B disposed between two skin layers, 144A and 144C. Each of these components of the film are discussed in more detail below.
First, the elastic film core layer 144B can be formed from one or more semi-crystalline polyolefins. Exemplary semi-crystalline polyolefins include polyethylene, polypropylene, blends and copolymers thereof. In one particular embodiment, a polyethylene is employed that is a copolymer of ethylene and an α-olefin, such as a C3-C20 α-olefin or C3-C12 α-olefin. Suitable α-olefins may be linear or branched (e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired α-olefin comonomers are 1-butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be from about 60 mole % to about 99 mole %, in some embodiments from about 80 mole % to about 98.5 mole %, and in some embodiments, from about 87 mole % to about 97.5 mole %. The α-olefin content may likewise range from about 1 mole % to about 40 mole %, in some embodiments from about 1.5 mole % to about 15 mole %, and in some embodiments, from about 2.5 mole % to about 13 mole %.
Particularly suitable polyethylene copolymers are those that are “linear” or “substantially linear.” The term “substantially linear” means that, in addition to the short chain branches attributable to comonomer incorporation, the ethylene polymer also contains long chain branches in the polymer backbone. “Long chain branching” refers to a chain length of at least 6 carbons. Each long chain branch may have the same comonomer distribution as the polymer backbone and be as long as the polymer backbone to which it is attached. Preferred substantially linear polymers are substituted with from 0.01 long chain branch per 1000 carbons to 1 long chain branch per 1000 carbons, and in some embodiments, from 0.05 long chain branch per 1000 carbons to 1 long chain branch per 1000 carbons. In contrast to the term “substantially linear”, the term “linear” means that the polymer lacks measurable or demonstrable long chain branches. That is, the polymer is substituted with an average of less than 0.01 long chain branch per 1000 carbons.
The density of a linear ethylene/α-olefin copolymer is a function of both the length and amount of the α-olefin. That is, the greater the length of the α-olefin and the greater the amount of α-olefin present, the lower the density of the copolymer. Although not necessarily required, linear polyethylene “plastomers” are particularly desirable in that the content of α-olefin short chain branching content is such that the ethylene copolymer exhibits both plastic and elastomeric characteristics—i.e., a “plastomer.” Because polymerization with α-olefin comonomers decreases crystallinity and density, the resulting plastomer normally has a density lower than that of a polyethylene thermoplastic polymer (e.g., LLDPE), which typically has a density (specific gravity) of from about 0.90 grams per cubic centimeter (g/cm3) to about 0.94 g/cm3, but approaching and/or overlapping that of an elastomer, which typically has a density of from about 0.85 g/cm3 to about 0.90 g/cm3, preferably from 0.86 to 0.89. For example, the density of the polypropylene (e.g., propylene/α-olefin copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.91 g/cm3. Despite having a density similar to elastomers, plastomers generally exhibit a higher degree of crystallinity, are relatively non-tacky, and may be formed into pellets that are non-adhesive-like and relatively free flowing.
Preferred polyethylenes for use in the present invention are ethylene-based copolymer plastomers available under the designation EXACT™ from ExxonMobil Chemical Company of Houston, Tex. Other suitable polyethylene plastomers are available under the designation ENGAGE™ and AFFINITY™ from Dow Chemical Company of Midland, Mich. An additional suitable polyethylene-based plastomer is an olefin block copolymer available from Dow Chemical Company of Midland, Mich. under the trade designation INFUSE™, which is an elastomeric copolymer of polyethylene. Still other suitable ethylene polymers are low density polyethylenes (LDPE), linear low density polyethylenes (LLDPE) or ultralow linear density polyethylenes (ULDPE), such as those available from The Dow Chemical Company under the designations ASPUN™ (LLDPE), DOWLEX™ (LLDPE) and ATTANE™ (ULDPE). Other suitable ethylene polymers are described in U.S. Pat. Nos. 4,937,299 to Ewen, et al., 5,218,071 to Tsutsui et al., 5,272,236 to Lai et al., and 5,278,272 to Lai, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Of course, the elastic film core layer 144B of the present invention is by no means limited to ethylene polymers. For instance, propylene plastomers may also be suitable for use in the film. Suitable plastomeric propylene polymers may include, for instance, polypropylene homopolymers, copolymers or terpolymers of propylene, copolymers of propylene with an α-olefin (e.g., C3-C20) comonomer, such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer content of the propylene polymer may be about 35 wt. % or less, in some embodiments from about 1 wt. % to about 20 wt. %, in some embodiments from about 2 wt. % to about 15 wt. %, and in some embodiments from about 3 wt. % to about 10 wt. %. Preferably, the density of the polypropylene (e.g., propylene/α-olefin copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.91 g/cm3.
Suitable propylene polymers are commercially available under the designations VISTAMAXX™ (e.g., 6102), a propylene-based elastomer from ExxonMobil Chemical Co. of Houston, Tex.; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMER™ available from Mitsui Petrochemical Industries; and VERSIFY™ available from Dow Chemical Co. of Midland, Mich. Other examples of suitable propylene polymers are described in U.S. Pat. Nos. 5,539,056 to Yang, et al., 5,596,052 to Resconi, et al., and 6,500,563 to Datta, et at, which are incorporated herein in their entirety by reference thereto for all purposes. In one particular embodiment, the elastic film core layer 144B includes polypropylene. The polypropylene can have a refractive index ranging from about 1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50, such as about 1.49 to help impart the material 200 with the desired light scattering and light absorbing properties.
Any of a variety of known techniques may generally be employed to form the semi-crystalline polyolefins. For instance, olefin polymers may be formed using a free radical or a coordination catalyst (e.g., Ziegler-Natta). Preferably, the olefin polymer is formed from a single-site coordination catalyst, such as a metallocene catalyst. Such a catalyst system produces ethylene copolymers in which the comonomer is randomly distributed within a molecular chain and uniformly distributed across the different molecular weight fractions. Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. Nos. 5,272,236 to Lai et al., 5,322,728 to Davis et al., 5,472,775 to Obiieski et al., 5,571,619 to McAlpin et al., and 6,090,325 to Wheat, et al., which are incorporated herein in their entirety by reference thereto for all purposes. Examples of metallocene catalysts include bis(n-butylcyclopentadienyl)titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium dichloride, bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl) zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride, isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene, titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride, and so forth. Polymers made using metallocene catalysts typically have a narrow molecular weight range. For instance, metallocene-catalyzed polymers may have polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching distribution, and controlled isotacticity.
The melt flow index (MI) of the semi-crystalline polyolefins may generally vary, but is typically in the range of about 0.1 grams per 10 minutes to about 100 grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes, determined at 190° C. The melt flow index is the weight of the polymer (in grams) that may be forced through an extrusion rheometer orifice (0.0825-inch diameter) when subjected to a force of 5000 grams in 10 minutes at 190° C., and may be determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin such as polypropylene, the elastic film core layer 144B can also include a fluorochemical additive to increase the surface energy of the elastic film 144, which, in turn, increases the imperviousness of the elastic film 144 to bodily fluids and biologic materials such as fatty oils that may be generated during very invasive surgeries. One example of a fluorochemical additive contemplated for use in the core layer 144B is a fluoroalkyl acrylate copolymer such as UNIDYNE® TG from Daikin. The fluorochemical additive can have a refractive index that is less than about 1.4 in order to lower the refractive index of the elastic film core layer 144B. For instance, the fluorochemical additive can have a refractive index ranging from about 1.2 to about 1.4, such as from about 1.22 to about 1.38, such as from about 1.24 to about 1.36. Without intending to be limited by any particular theory, it is believed that the fluorochemical additive segregates to the surface of the polyolefin film, where a lower refractive index region is formed, which enhances light scattering of the film as compared to films that are free of a fluorochemical additive. Regardless of the particular fluorochemical additive utilized, the fluorochemical additive can be present in the elastic film core layer 144B in an amount ranging from about 0.1 wt. % to about 5 wt. %, such as from about 0.5 wt. % to about 4wt. %, such as from about 1 wt. % to about 3 wt. % based on the total weight of the elastic film core layer 144B. In one particular embodiment, the fluorochemical additive can be present in an amount of about 1.5 wt. % based on the total weight of the elastic film core layer 144B.
In one embodiment, the elastic film core layer 144B can also include a filler. Fillers are particulates or other forms of material that may be added to the film polymer extrusion blend and that will not chemically interfere with the extruded film, but which may be uniformly dispersed throughout the film. Fillers may serve a variety of purposes, including enhancing film opacity and/or breathability (i.e., vapor-permeable and substantially liquid-impermeable). For instance, filled films may be made breathable by stretching, which causes the polymer to break away from the filler and create microporous passageways. Breathable microporous elastic films are described, for example, in U.S. Pat. Nos. 5,932,497 to Morman, et al., 5,997,981, 6,015,764, and 6,111,163 to McCormack, et al., and 6,461,457 to Taylor, et al., which are incorporated herein in their entirety by reference thereto for all purposes. Examples of suitable fillers include, but are not limited to, calcium carbonate, various kinds of clay, silica, alumina, barium carbonate, sodium carbonate, magnesium carbonate, talc, barium sulfate, magnesium sulfate, aluminum sulfate, zeolites, cellulose-type powders, kaolin, mica, carbon, calcium oxide, magnesium oxide, aluminum hydroxide, pulp powder, wood powder, cellulose derivatives, chitin and chitin derivatives. In one particular embodiment, the filler in the core layer 144B can include calcium carbonate, which can provide the elastic film 144, and thus the material 200, with light scattering and light absorbing properties to help reduce glare, particularly after stretching the calcium carbonate-containing core layer 144B, which further increases the opacity and increases the light scattering of the material 200. For instance, the calcium carbonate (or any other suitable filler) can have a refractive index ranging from about 1.60 to about 1.72, such as from about 1.62 to about 1.70, such as from about 1.64 to about 1.68, such as about 1.66, to impart the material 200 with the desired light scattering and light absorbing properties. In certain cases, the filler content of the film may range from about 50 wt. % to about 85 wt. %, in some embodiments, from about 55 wt. % to about 80 wt. %, and in some embodiments, from about 60 wt. % to about 75 wt. % of the elastic film core layer 1446 based on the total weight of the elastic film core layer 144B.
Further, the elastic film core layer 1446 can also include one or more pigments to help achieve the desired gray color of the gown 100. Examples of suitable pigments include, but are not limited to, titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites, kaolin, mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and combinations thereof. In certain cases, for instance, the elastic film core layer 144B can include titanium dioxide in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the core layer 144B. The titanium dioxide can have a refractive index ranging from about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from about 2.6 to about 2.8, such as about 2.76, to impart the material 200 with the desired light scattering and light absorbing properties. Further, the elastic film core layer 1446 can also include carbon black in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the core layer 144B. The carbon black can have a refractive index ranging from about 1.2 to about 2.4, such as from about 1.4 to about 2.2, such as from about 1.6 to about 2 to impart the material 200 with the desired light scattering and light absorbing properties. The elastic film core layer 144B can also include a blue pigment in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The combination of the carbon black and blue pigment improves the ability of the elastic film core layer 144B to absorb light.
Further, like the elastic film core layer 144B, the elastic film skin layers 144A and 144C that sandwich the elastic film core layer 1446 can also be formed from one or more semi-crystalline polyolefins. Exemplary semi-crystalline polyolefins include polyethylene, polypropylene, blends and copolymers thereof. In one particular embodiment, a polyethylene is employed that is a copolymer of ethylene and an α-olefin, such as a C3-C20 α-olefin or C3-C12 α-olefin. Suitable α-olefins may be linear or branched (e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired α-olefin comonomers are 1-butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be from about 60 mole % to about 99 mole %, in some embodiments from about 80 mole % to about 98.5 mole %, and in some embodiments, from about 87 mole % to about 97.5 mole %. The α-olefin content may likewise range from about 1 mole % to about 40 mole %, in some embodiments from about 1.5 mole % to about 15 mole %, and in some embodiments, from about 2.5 mole % to about 13 mole %.
Particularly suitable polyethylene copolymers are those that are “linear” or “substantially linear.” The term “substantially linear” means that, in addition to the short chain branches attributable to comonomer incorporation, the ethylene polymer also contains long chain branches in the polymer backbone. “Long chain branching” refers to a chain length of at least 6 carbons. Each long chain branch may have the same comonomer distribution as the polymer backbone and be as long as the polymer backbone to which it is attached. Preferred substantially linear polymers are substituted with from 0.01 long chain branch per 1000 carbons to 1 long chain branch per 1000 carbons, and in some embodiments, from 0.05 long chain branch per 1000 carbons to 1 long chain branch per 1000 carbons. In contrast to the term “substantially linear”, the term “linear” means that the polymer lacks measurable or demonstrable long chain branches. That is, the polymer is substituted with an average of less than 0.01 long chain branch per 1000 carbons.
The density of a linear ethylene/α-olefin copolymer is a function of both the length and amount of the α-olefin. That is, the greater the length of the α-olefin and the greater the amount of α-olefin present, the lower the density of the copolymer. Although not necessarily required, linear polyethylene “plastomers” are particularly desirable in that the content of α-olefin short chain branching content is such that the ethylene copolymer exhibits both plastic and elastomeric characteristics—i.e., a “plastomer.” Because polymerization with α-olefin comonomers decreases crystallinity and density, the resulting plastomer normally has a density lower than that of a polyethylene thermoplastic polymer (e.g., LLDPE), which typically has a density (specific gravity) of from about 0.90 grams per cubic centimeter (g/cm3) to about 0.94 g/cm3, but approaching and/or overlapping that of an elastomer, which typically has a density of from about 0.85 g/cm3 to about 0.90 g/cm3, preferably from 0.86 to 0.89. For example, the density of the polyethylene plastomer may be 0.91 g/cm3 or less, in some embodiments from about 0.85 g/cm3 to about 0.90 g/cm3, in some embodiments, from 0.85 g/cm3 to 0.88 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.87 g/cm3. Despite having a density similar to elastomers, plastomers generally exhibit a higher degree of crystallinity, are relatively non-tacky, and may be formed into pellets that are non-adhesive-like and relatively free flowing.
Preferred polyethylenes for use in the present invention are ethylene-based copolymer plastomers available under the designation EXACT™ from ExxonMobil Chemical Company of Houston, Tex. Other suitable polyethylene plastomers are available under the designation ENGAGE™ and AFFINITY™ from Dow Chemical Company of Midland, Mich. An additional suitable polyethylene-based plastomer is an olefin block copolymer available from Dow Chemical Company of Midland, Mich. under the trade designation INFUSE™, which is an elastomeric copolymer of polyethylene. Still other suitable ethylene polymers are low density polyethylenes (LDPE), linear low density polyethylenes (LLDPE) or ultralow linear density polyethylenes (ULDPE), such as those available from The Dow Chemical Company under the designations ASPUN™ (LLDPE), DOWLEX™ (LLDPE) and ATTANE™ (ULDPE). Other suitable ethylene polymers are described in U.S. Pat. Nos. 4,937,299 to Ewen, et al., 5,218,071 to Tsutsui et al., 5,272,236 to Lai, et al., and 5,278,272 to Lai, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Of course, the elastic film skin layers 144A and 144C of the present invention are by no means limited to ethylene polymers. For instance, propylene plastomers may also be suitable for use in the film. Suitable plastomeric propylene polymers may include, for instance, polypropylene homopolymers, copolymers or terpolymers of propylene, copolymers of propylene with an α-olefin (e.g., C3-C20) comonomer, such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer content of the propylene polymer may be about 35 wt. % or less, in some embodiments from about 1 wt. % to about 20 wt. %, in some embodiments from about 2 wt. % to about 15 wt. %, and in some embodiments from about 3 wt. % to about 10 wt. %. The density of the polypropylene (e.g., propylene/α-olefin copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.91 g/cm3. In one particular embodiment, the elastic film skin layers 144A and 144C can include a copolymer of polypropylene and polyethylene. The polypropylene can have a refractive index ranging from about 1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50, such as about 1.49, while the polyethylene can have a refractive index ranging from about 1.46 to about 1.56, such as from about 1.48 to about 1.54, such as from about 1.50 to about 1.52, such as about 1.51, to impart the material 200 with the desired light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the designations VISTAMAXX™ (e.g., 6102), a propylene-based elastomer from ExxonMobil Chemical Co. of Houston, Tex.; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMER™ available from Mitsui Petrochemical Industries; and VERSIFY™ available from Dow Chemical Co. of Midland, Mich. Other examples of suitable propylene polymers are described in U.S. Pat. Nos. 5,539,056 to Yang, et al., 5,596,052 to Resconi, et al., and 6,500,563 to Datta, et at, which are incorporated herein in their entirety by reference thereto for all purposes.
Any of a variety of known techniques may generally be employed to form the semi-crystalline polyolefins. For instance, olefin polymers may be formed using a free radical or a coordination catalyst (e.g., Ziegler-Natta). Preferably, the olefin polymer is formed from a single-site coordination catalyst, such as a metallocene catalyst. Such a catalyst system produces ethylene copolymers in which the comonomer is randomly distributed within a molecular chain and uniformly distributed across the different molecular weight fractions. Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. Nos. 5,272,236 to Lai et al., 5,322,728 to Davis et al., 5,472,775 to Obijeski et al., 5,571,619 to McAlpin et al., and 6,090,325 to Wheat, et al., which are incorporated herein in their entirety by reference thereto for all purposes. Examples of metallocene catalysts include bis(n-butylcyclopentadienyl)titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconium dichloride, bis(methylcyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl) zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride, isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene, titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride, and so forth. Polymers made using metallocene catalysts typically have a narrow molecular weight range. For instance, metallocene-catalyzed polymers may have polydispersity numbers (Mw/Mn) of below 4, controlled short chain branching distribution, and controlled isotacticity.
The melt flow index (MI) of the semi-crystalline polyolefins may generally vary, but is typically in the range of about 0.1 grams per 10 minutes to about 100 grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes, determined at 190° C. The melt flow index is the weight of the polymer (in grams) that may be forced through an extrusion rheometer orifice (0.0825-inch diameter) when subjected to a force of 5000 grams in 10 minutes at 190° C., and may be determined in accordance with ASTM Test Method D1238-E.
In addition, it is noted that the elastic film skin layers 144A and 144C are free of the fluorochemical additive that is present in the elastic film core layer 144B. As a result, the skin layers 144A and 144C have a higher refractive index than the elastic film core layer 144B, as the fluorochemical additive tends to lower the refractive index of the core layer 144B. The resulting difference in refractive indices at the interfaces between the core layer 1446 and the skin layers 144A and 144C of the elastic film 144 is thought to enhance light scattering, which can result in a high level of opacity and a low level of light reflection (e.g., reduced glare).
In any event, regardless of the number of layers present in the elastic film 144 and regardless of the specific polymer or polymers and additives used to form the elastic film 144, the elastic film 144 can have a basis weight ranging from about 5 gsm to about 50 gsm, such as from about 10 gsm to about 40 gsm, such as from about 15 gsm to about 30 gsm. In one particular embodiment, the elastic film 144 can have a basis weight of about 20 gsm (about 0.6 osy).
C. Spunbond Meltblown Spunbond (SMS) Laminate
The first material 200 also includes an SMS laminate 146 that is attached to the skin layer 144C of the elastic film 144. One of the spunbond layers 146C of the SMS laminate 146 can form the inner-facing surface 204 of the first material 200 of the gown 100, which is used to form the front panel 102, the sleeves 104, and the front fastening means 116. Further, it is to be understood that the spunbond layer 146A, which is adjacent the skin layer 144C, the spunbond layer 146C, and the meltblown layer 1466 disposed therebetween can be formed from any of the polymers (e.g., polyolefins) mentioned above with respect to the outer spunbond layer 142. In other words, the SMS laminate 146 can be formed from any suitable polymer that provides softness, stretch, and pliability to the first material 200.
In one particular embodiment, the SMS laminate 146 can include a first spunbond layer 146A and a second spunbond layer 146C, where the spunbond layers 146A and 146C can be formed from any suitable polymer that provides softness, stretch, and pliability to the first material 200. For instance, the spunbond layers 146A and 146C can be formed from a semi-crystalline polyolefin. Exemplary polyolefins may include, for instance, polyethylene, polypropylene, blends and copolymers thereof. In one particular embodiment, a polyethylene is employed that is a copolymer of ethylene and an α-olefin, such as a C3-C20 α-olefin or C3-C12 α-olefin. Suitable α-olefins may be linear or branched (e.g., one or more C1-C3 alkyl ranches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired α-olefin co-monomers are 1-butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be from about 60 mole % to about 99 mole %, in some embodiments from about 80 mole % to about 98.5 mole %, and in some embodiments, from about 87 mole % to about 97.5 mole %. The α-olefin content may likewise range from about 1 mole % to about 40 mole %, in some embodiments from about 1.5 mole % to about 15 mole %, and in some embodiments, from about 2.5 mole % to about 13 mole %.
The density of the polyethylene may vary depending on the type of polymer employed, but generally ranges from 0.85 to 0.96 grams per cubic centimeter (“g/cm3”). Polyethylene “plastomers”, for instance, may have a density in the range of from 0.85 to 0.91 g/cm3. Likewise, “linear low density polyethylene” (“LLDPE”) may have a density in the range of from 0.91 to 0.940 g/cm3; “low density polyethylene” (“LDPE”) may have a density in the range of from 0.910 to 0.940 g/cm3; and “high density polyethylene” (“HDPE”) may have density in the range of from 0.940 to 0.960 g/cm3. Densities may be measured in accordance with ASTM 1505. Particularly suitable ethylene-based polymers for use in the present invention may be available under the designation EXACT™ from ExxonMobil Chemical Company of Houston, Tex. Other suitable polyethylene plastomers are available under the designation ENGAGE™ and AFFINITY™ from Dow Chemical Company of Midland, Mich. Still other suitable ethylene polymers are available from The Dow Chemical Company under the designations DOWLEX™ (LLDPE) and ATTANE™ (ULDPE). Other suitable ethylene polymers are described in U.S. Pat. No. 4,937,299 to Ewen et al.; U.S. Pat. No. 5,218,071 to Tsutsui et al.; U.S. Pat. No. 5,272,236 to Lai, et al.; and U.S. Pat. No. 5,278,272 to Lai, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Of course, the spunbond layers 146A and 146C of the first material 200 are by no means limited to ethylene polymers. For instance, propylene polymers may also be suitable for use as a semi-crystalline polyolefin. Suitable propylene polymers may include, for instance, polypropylene homopolymers, as well as copolymers or terpolymers of propylene with an α-olefin (e.g., C3-C20) comonomer, such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer content of the propylene polymer may be about 35 wt. % or less, in some embodiments from about 1 wt. % to about 20 wt. %, in some embodiments, from about 2 wt. % to about 15 wt. %, and in some embodiments from about 3 wt. % to about 10 wt. %. The density of the polypropylene (e.g., propylene/α-olefin copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.91 g/cm3. In one particular embodiment, the spunbond layers 146A and 146C can each include a copolymer of polypropylene and polyethylene. The polypropylene can have a refractive index ranging from about 1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50, such as about 1.49, while the polyethylene can have a refractive index ranging from about 1.46 to about 1.56, such as from about 1.48 to about 1.54, such as from about 1.50 to about 1.52, such as about 1.51, to impart the material 200 with the desired light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the designations VISTAMAXX™ from ExxonMobil Chemical Co. of Houston, Tex.; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMER™ available from Mitsui Petrochemical Industries; and VERSIFY™ available from Dow Chemical Co. of Midland, Mich. Other examples of suitable propylene polymers are described in U.S. Pat. Nos. 6,500,563 to Datta, et al.; 5,539,056 to Yang, et al.; and 5,596,052 to Resconi, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Any of a variety of known techniques may generally be employed to form the polyolefins. For instance, olefin polymers may be formed using a free radical or a coordination catalyst (e.g., Ziegler-Natta or metallocene). Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. Nos. 5,571,619 to McAlpin et at; 5,322,728 to Davis et al.; 5,472,775 to Obiieski et al.; 5,272,236 to Lai et al.; and 6,090,325 to Wheat, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
The melt flow index (MI) of the polyolefins may generally vary, but is typically in the range of about 0.1 grams per 10 minutes to about 100 grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes, determined at 190° C. The melt flow index is the weight of the polymer (in grams) that may be forced through an extrusion rheometer orifice (0.0825-inch diameter) when subjected to a force of 2160 grams in 10 minutes at 190° C., and may be determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin, the spunbond layers 146A and 146C can each include a slip additive to enhance the softness of the spunbond layers 146A and 146C. The slip additive can also reduce the glare of the first material 200 in the operating room by reducing the light reflectance of the first material and can also render the first material 200 more opaque than the standard gown material when contacted with fats and lipids during surgery, where the standard gown material turns transparent upon contact with fats and lipids, which can result in the wearer having some concern that the barrier properties of a standard gown have been compromised.
Variants of fatty acids can be used as slip additives. For example, the slip additive can be erucamide, oleamide, stearamide, behenamide, oleyl palmitamide, stearyl erucamide, ethylene bis-oleamide, N,N′-Ethylene Bis(Stearamide) (EBS), or a combination thereof. Further, the slip additive have a refractive index ranging from about 1.42 to about 1.52, such as from about 1.44 to about 1.50, such as from about 1.46 to about 1.48, such as about 1.47, to impart the material 200 with the desired light scattering and light absorbing properties by reducing the refractive index. The slip additive can be present in each of the first spunbond layer 146A and the second spunbond layer 146C in an amount ranging from about 0.25 wt. % to about 6 wt. %, such as from about 0.5 wt. % to about 5 wt. %, such as from about 1 wt. % to about 4 wt. % based on the total weight of the particular spunbond layer 146A or 146C. In one particular embodiment, the slip additive can be present in an amount of about 2 wt. % based on the total weight of the particular spunbond layer 146A or 146C.
In addition to the polyolefin and slip additive, the spunbond layers 146A and 146C can also include one or more pigments to help achieve the desired gray color of the gown 100. Examples of suitable pigments include, but are not limited to, titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites, kaolin, mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and combinations thereof. In certain cases, for instance, each of the spunbond layers 146A or 146C can include titanium dioxide in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the particular spunbond layer 146A or spunbond layer 146C. The titanium dioxide can have a refractive index ranging from about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from about 2.6 to about 2.8, such as about 2.76, to impart the material 200 with the desired light scattering and light absorbing properties. Further, each of the spunbond layers 146A or 146C can also include carbon black in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the particular spunbond layer 146A or spunbond layer 146C. The carbon black can have a refractive index ranging from about 1.2 to about 2.4, such as from about 1.4 to about 2.2, such as from about 1.6 to about 2 to impart the material 200 with the desired light scattering and light absorbing properties. In addition, each of the spunbond layers 146A or 146C can also include a blue pigment in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The combination of the carbon black and blue pigment improves the ability of the spunbond layers 146A or 146C to absorb light.
The meltblown layer 146B of the spunbond-meltblown-spunbond second material 300 can also be formed from any of the semi-crystalline polyolefins discussed above with respect to the first spunbond layer 146A and the second spunbond layer 146C of the first material 200. In one particular embodiment, the meltblown layer 146B can be formed from 100% polypropylene.
Regardless of the specific polymer or polymers and additives used to form the SMS laminate 146, the SMS laminate 146 can have a basis weight ranging from about 5 gsm to about 50 gsm, such as from about 10 gsm to about 40 gsm, such as from about 15 gsm to about 30 gsm. In one particular embodiment, the SMS laminate 146 can have a basis weight of about 22 gsm (about 0.65 osy).
Despite the use of a front panel 102 and sleeves 104 that are formed from a moisture-vapor breathable first material 200, the amount of heat that becomes trapped can be uncomfortable to the wearer. As such, the present inventor has discovered that the placement of highly breathable and air permeable first rear panel 120 and second rear panel 120 formed from a second material 300 in the rear 160 of the gown 100 that overlap when the gown 100 is secured with, for instance, hook and loop fastening means 168, can facilitate the dissipation of trapped humidity and heat between the gown 100 and the wearer. In one particular embodiment, the second material 300 can be in the form of a spunbond-meltblown-spunbond (SMS) laminate that has enhanced air breathability in order to facilitate removal of trapped heated air and moisture from the gown 100. For instance, the second material 300 allows for an air volumetric flow rate ranging from about 20 standard cubic feet per minute (scfm) to about 80 scfm, such as from about 30 scfm to about 70 scfm, such as from about 40 scfm to about 60 scfm, as determined at 1 atm (14.7 psi) and 20° C. (68° F.). In one particular embodiment, the second material 300 allows for an air volumetric flow rate of about 45 scfm. Because the first rear panel 120 and the second rear panel 122 can be formed from the air breathable second material 300, the heat and humidity that can build up inside the space between the gown 100 and the wearer's body can escape via convection and/or by movement of air as the movement of the gown materials 200 and 300 changes the volume of space between the gown 100 and the wearer's body. Further, the SMS laminate used to form the second material 300 can have a basis weight ranging from about 20 gsm to about 80 gsm, such as from about 25 gsm to about 70 gsm, such as from about 30 gsm to about 60 gsm. In one particular embodiment, the second material 300 can have a basis weight of about 40 gsm (about 1.2 osy).
In addition to the first rear panel 120 and the second rear panel 122, the rear fastening means (ties) 118 can also be formed from the second material 300. The various layers of the second material 300 are discussed in more detail below.
A. First and Second Spunbond Layers
The first spunbond layer 148 and second spunbond layer 152 of the second material 300 can be formed from any suitable polymer that provides softness and air breathability to the second material 300. For instance, the first spunbond layer 148 and the second spunbond layer 152 can be formed from a semi-crystalline polyolefin. Exemplary polyolefins may include, for instance, polyethylene, polypropylene, blends and copolymers thereof. In one particular embodiment, a polyethylene is employed that is a copolymer of ethylene and an α-olefin, such as a C3-C20 α-olefin or C3-C12 α-olefin. Suitable α-olefins may be linear or branched (e.g., one or more C1-C3 alkyl branches, or an aryl group). Specific examples include 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl or propyl substituents; 1-heptene with one or more methyl, ethyl or propyl substituents; 1-octene with one or more methyl, ethyl or propyl substituents; 1-nonene with one or more methyl, ethyl or propyl substituents; ethyl, methyl or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly desired α-olefin co-monomers are 1-butene, 1-hexene and 1-octene. The ethylene content of such copolymers may be from about 60 mole % to about 99 mole %, in some embodiments from about 80 mole % to about 98.5 mole %, and in some embodiments, from about 87 mole % to about 97.5 mole %. The α-olefin content may likewise range from about 1 mole % to about 40 mole %, in some embodiments from about 1.5 mole % to about 15 mole %, and in some embodiments, from about 2.5 mole % to about 13 mole %.
The density of the polyethylene may vary depending on the type of polymer employed, but generally ranges from 0.85 to 0.96 grams per cubic centimeter (“g/cm3”). Polyethylene “plastomers”, for instance, may have a density in the range of from 0.85 to 0.91 g/cm3. Likewise, “linear low density polyethylene” (“LLDPE”) may have a density in the range of from 0.91 to 0.940 g/cm3; “low density polyethylene” (“LDPE”) may have a density in the range of from 0.910 to 0.940 g/cm3; and “high density polyethylene” (“HDPE”) may have density in the range of from 0.940 to 0.960 g/cm3. Densities may be measured in accordance with ASTM 1505. Particularly suitable ethylene-based polymers for use in the present invention may be available under the designation EXACT™ from ExxonMobil Chemical Company of Houston, Tex. Other suitable polyethylene plastomers are available under the designation ENGAGE™ and AFFINITY™ from Dow Chemical Company of Midland, Mich. Still other suitable ethylene polymers are available from The Dow Chemical Company under the designations DOWLEX™ (LLDPE) and ATTANE™ (ULDPE). Other suitable ethylene polymers are described in U.S. Pat. Nos. 4,937,299 to Ewen et al.; 5,218,071 to Tsutsui et al.; 5,272,236 to Lai et al.; and 5,278,272 to Lai, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Of course, the first spunbond layer 148 and the second spunbond layer 152 of the second material 300 are by no means limited to ethylene polymers. For instance, propylene polymers may also be suitable for use as a semi-crystalline polyolefin. Suitable propylene polymers may include, for instance, polypropylene homopolymers, as well as copolymers or terpolymers of propylene with an α-olefin (e.g., C3-C20) comonomer, such as ethylene, 1-butene, 2-butene, the various pentene isomers, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-unidecene, 1-dodecene, 4-methyl-1-pentene, 4-methyl-1-hexene, 5-methyl-1-hexene, vinylcyclohexene, styrene, etc. The comonomer content of the propylene polymer may be about 35 wt. % or less, in some embodiments from about 1 wt. % to about 20 wt. %, in some embodiments, from about 2 wt. % to about 15 wt. %, and in some embodiments from about 3 wt. % to about 10 wt. %. The density of the polypropylene (e.g., propylene/α-olefin copolymer) may be 0.95 grams per cubic centimeter (g/cm3) or less, in some embodiments, from 0.85 to 0.92 g/cm3, and in some embodiments, from 0.85 g/cm3 to 0.91 g/cm3. In one particular embodiment, the spunbond layers 148 and 152 can each include a copolymer of polypropylene and polyethylene. The polypropylene can have a refractive index ranging from about 1.44 to about 1.54, such as from about 1.46 to about 1.52, such as from about 1.48 to about 1.50, such as about 1.49, while the polyethylene can have a refractive index ranging from about 1.46 to about 1.56, such as from about 1.48 to about 1.54, such as from about 1.50 to about 1.52, such as about 1.51, to impart the material 300 with the desired light scattering and light absorbing properties.
Suitable propylene polymers are commercially available under the designations VISTAMAXX™ from ExxonMobil Chemical Co. of Houston, Tex.; FINA™ (e.g., 8573) from Atofina Chemicals of Feluy, Belgium; TAFMER™ available from Mitsui Petrochemical Industries; and VERSIFY™ available from Dow Chemical Co. of Midland, Mich. Other examples of suitable propylene polymers are described in U.S. Pat. Nos. 6,500,563 to Datta, et al.; 5,539,056 to Yang, et al.; and 5,596,052 to Resconi, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
Any of a variety of known techniques may generally be employed to form the polyolefins. For instance, olefin polymers may be formed using a free radical or a coordination catalyst (e.g., Ziegler-Natta or metallocene). Metallocene-catalyzed polyolefins are described, for instance, in U.S. Pat. Nos. 5,571,619 to McAlpin et at; 5,322,728 to Davis et al.; 5,472,775 to Obijeski et al.; 5,272,236 to Lai et al.; and 6,090,325 to Wheat, et al., which are incorporated herein in their entirety by reference thereto for all purposes.
The melt flow index (MI) of the polyolefins may generally vary, but is typically in the range of about 0.1 grams per 10 minutes to about 100 grams per 10 minutes, in some embodiments from about 0.5 grams per 10 minutes to about 30 grams per 10 minutes, and in some embodiments, about 1 to about 10 grams per 10 minutes, determined at 190° C. The melt flow index is the weight of the polymer (in grams) that may be forced through an extrusion rheometer orifice (0.0825-inch diameter) when subjected to a force of 2160 grams in 10 minutes at 190° C., and may be determined in accordance with ASTM Test Method D1238-E.
In addition to a polyolefin, the first spunbond layer 148 and the second spunbond layer 152 can also include a slip additive to enhance the softness of the first spunbond layer 148 and the second spunbond layer 152. The slip additive can also reduce the coefficient of friction and increase the hydrohead of the first spunbond layer 148 and the second spunbond layer 152 of the first rear panel 120 and second rear panel 122. Such a reduction in the coefficient of friction lessens the chance of the gown 100 being cut or damaged due to abrasions and also prevents fluids from seeping through the second material 300. Instead, at least in part due to the inclusion of the slip additive, fluid that contacts the outer-facing surface 302 of the gown 100 can remain in droplet form and run vertically to the distal end 156 of the gown 100 and onto the floor. The slip additive can also reduce the glare of the second material 300 in the operating room by reducing the light reflectance of the first material and can also render the second material 300 more opaque than the standard gown material when contacted with fats and lipids during surgery, where the standard gown material turns transparent upon contact with fats and lipids, which can result in the wearer having some concern that the barrier properties of a standard gown have been compromised.
The slip additive can function by migrating to the surface of the polymer used to form the first spunbond layer 148 and/or the second spunbond layer 152, where it can provide a coating that reduces the coefficient of friction of the outer-facing surface 302 and/or body-facing surface or inner-facing surface 304 of the first material 300. Variants of fatty acids can be used as slip additives. For example, the slip additive can be erucamide, oleamide, stearamide, behenamide, oleyl palmitamide, stearyl erucamide, ethylene bis-oleamide, N,N′-Ethylene Bis(Stearamide) (EBS), or a combination thereof. Further, the slip additive have a refractive index ranging from about 1.42 to about 1.52, such as from about 1.44 to about 1.50, such as from about 1.46 to about 1.48, such as about 1.47, to impart the material 200 with the desired light scattering and light absorbing properties. The slip additive can be present in the first spunbond layer 148 and/or the second spunbond layer 152 of the second material 300 in an amount ranging from about 0.25 wt. % to about 6 wt. %, such as from about 0.5 wt. % to about 5 wt. %, such as from about 1 wt. % to about 4 wt. % based on the total weight of the first spunbond layer 148 and/or the second spunbond layer 152. In one particular embodiment, the slip additive can be present in an amount of about 2 wt. % based on the total weight of the first spunbond layer 148 and/or the second spunbond layer 152.
In addition to the polyolefin and slip additive, the spunbond layers 148 and 152 can also include one or more pigments to help achieve the desired gray color of the gown 100. Examples of suitable pigments include, but are not limited to, titanium dioxide (e.g., SCC 11692 concentrated titanium dioxide), zeolites, kaolin, mica, carbon black, calcium oxide, magnesium oxide, aluminum hydroxide, and combinations thereof. In certain cases, for instance, each of the spunbond layers 148 or 152 can include titanium dioxide in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the particular spunbond layer 148 or 152. The titanium dioxide can have a refractive index ranging from about 2.2 to about 3.2, such as from about 2.4 to about 3, such as from about 2.6 to about 2.8, such as about 2.76, to impart the material 200 with the desired light scattering and light absorbing properties. Further, each of the spunbond layers 148 or 152 can also include carbon black in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the particular spunbond layer 148 or spunbond layer 152. The carbon black can have a refractive index ranging from about 1.2 to about 2.4, such as from about 1.4 to about 2.2, such as from about 1.6 to about 2 to impart the material 300 with the desired light scattering and light absorbing properties. In addition, each of the spunbond layers 148 or 152 can also include a blue pigment in an amount ranging from about 0.1 wt. % to about 10 wt. %, in some embodiments, from about 0.5 wt. % to about 7.5 wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % based on the total weight of the individual layer. The combination of the carbon black and blue pigment improves the ability of the spunbond layers 148 or 152 to absorb light.
B. Meltblown Layer
The meltblown layer 150 of the spunbond-meltblown-spunbond second material 300 can also be formed from any of the semi-crystalline polyolefins discussed above with respect to the first spunbond layer 148 and the second spunbond layer 152 of the second material 300. In one particular embodiment, the meltblown layer 150 can be formed from 100% polypropylene.
The collar 110 and the cuffs 106 of the gown 100 of the present invention can be formed from a woven or knit material that is air breathable, soft, and extensible. The collar 110 can also be liquid resistant. In one particular embodiment, the collar 110 and the cuffs 104 can be formed from a knit polyester that is air breathable yet liquid resistant. For instance, the collar 110 can have an air permeability ranging from about 100 ft3/ft2/minute to about 370 ft3/ft2/minute, such as from about 175 ft3/ft2/minute to about 360 ft3/ft2/minute, such as from about 250 ft3/ft2/minute to about 350 ft3/ft2/minute. The breathability of the collar 110 facilitates the dissipation of heat through the neck opening 108 of the gown 100 to provide comfort to the wearer. Further, because the material from which the collar 110 is formed is extensible, the collar 110 can stretch and conform to a wearer's particular neck dimensions to lay flat against the wearer's neck and prevent any gapping of the collar 110, which could allow bone fragments, blood splatter, and other biologic materials to come into contact with the wearer. The extensibility of the collar 110 also allows a single collar size to fit many different wearers who have different sized necks. Moreover, the stretch and recovery properties of the collar allow for the wearer to have freedom of movement without sacrificing the ability of the collar to form a snug fit about the wearer. Further, as mentioned above, at the rear 160 of the gown 100, the collar 110 can have a tapered section 140 to allow for easy gown removal and to prevent the hook material 136 and loop material 138 of the hook and loop rear fastening means 168 from interfering with the collar 110. For instance, since the collar 110 is stretchable, any interference between the hook and loop rear fastening means 168 and the collar 110, such as would be the case if the collar 110 were not tapered to have a smaller height H2 and instead had a height H1 at the second end 130 of the first portion 126 of the collar 110 and at the second end 132 of the second portion 128 of the collar 110 (see
The present invention also encompasses a method for forming a collar on a disposable surgical gown. The method includes the following steps: providing a first collar portion having a first end, a second end and a lower edge; attaching the first collar portion along its attachment side to a disposable gown to form a first section of a collar; providing a second collar portion having a first end, a second end and a lower edge; and attaching the second collar portion along its lower edge to a disposable gown to form a second section of a collar. When the first and second collar portions are attached, the first end of the first portion and the first end of the second portion meet at a front of the collar to form a v-neck shape and the second end of the first portion and the second end of the second portion meet at a rear of the collar to define a neck opening. According to the method, the v-neck shape at the front of the collar forms an angle of greater than 90° at the neck opening, and the second end of the first portion and the second end of the second portion are tapered.
In an aspect of the method, the disposable gown may have a front panel, a first sleeve, a second sleeve, a first rear panel, and a second rear panel. The first collar portion is attached to the front panel, first sleeve, and first rear panel, while the second collar portion is attached to the front panel, second sleeve, and second rear panel. The first collar portion and second collar portion may be attached to the disposable gown by sewing, ultrasonic bonding, adhesive bonding, thermal bonding or combinations thereof.
The present invention may be better understood with reference to the following examples.
In Example 1, the opacity (diffuse reflectance), scattering power, scattering coefficient, absorption power, absorption coefficient, and transmittance were determined for the elastic film nonwoven laminate of the present invention according to a standard TAPPI test method for paper using C-illuminant as the light source, which is similar to light sources used in hospital operating rooms. The same properties were also determined for three commercially available materials used in disposable surgical gowns. The basis weight for the materials was also determined. The results are summarized in Table 1 below:
As shown above, the material used in the disposable surgical gown of the present invention has a lower transmittance and higher opacity than the other four materials.
Next, the opacity (diffuse reflectance), scattering power, scattering coefficient, absorption power, absorption coefficient, and transmittance for the various layers of the material used to form the front panel and sleeves (the elastic film nonwoven laminate) were determined as in Example 1. The results are shown below in Table 2.
As shown above, the optical properties of the elastic film nonwoven laminate used to form the disposable surgical gown of the present invention, (e.g., the combined SMS laminate (inner-facing surface or body-facing surface), film, and spunbond (outer-facing surface)), when such properties are determined by for its outer-facing surface (the SB side), are indicative of a gown material that has reduced glare compared to the individual components of the laminate each tested alone. Specifically, the opacity is increased to 98.6%, the scattering power is increased to 1.97, the scattering coefficient is increased to 30 m2/g, and absorption coefficient is reduced to 13.6 m2/g, and the transmittance is reduced to 0.107.
Next, in Example 3, the air permeability of the collar was determined for 10 separate samples. The results are shown below in Table 3.
As shown, the air permeability of the 10 samples of material used to form the collar of the present invention that were tested ranged from 292 ft3/ft2/minute to 340 ft3/ft2/minute.
Next, in Example 4, various mechanical properties of the material used to form the collar of the present invention were determined for 20 separate samples. The results are shown below in Tables 4 and 5. For all testing, a tensile testing machine was utilized, where the crosshead speed was set to 500+/−10 millimeters/minute and the gage length (initial vertical distance between grips) was 50+/−1 millimeter.
Referring to Table 4, the peak load (grams-force or gf), elongation at break (%), load at break (gf), elongation at which the force equals 1400 grams on the first upward elongation curve (%), elongation at which the force equals 2000 grams on the first upward elongation curve (%), hysteresis loss (%), elongation at peak load—break cycle (%), energy loading at break cycle (g*cm), percent set at 0 grams (%), percent set at 10 grams (%), energy loading (g*cm), energy unloading (g*cm), and energy unloading/energy loading.
As shown below, the hysteresis loss generally ranged from 55.9% to 65.1% with one outlier at 100%, where the lower the hysteresis loss, the more the collar material retains its elastic behavior and acts like a rubber band.
Referring now to Tables 5 and 6, to determine the load during extension (loading) and retraction (unloading) for the samples, the load was measured at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% elongation, and then the load was determined during retraction at 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, and 10% elongation. As shown below, the load during extension at the measured percent elongations ranges increases on average from 6.5 gf at 10% elongation to 45.3 gf at 100% elongation, while the load during retraction at the measured percent elongations decreases on average from 83.2 gf at 100% elongation to −1.1 gf at 10% elongation, where a lower extension load indicates that less force is required to elongate the sample to a particular position so that the sample is perceived to be stretchy, while a higher retraction load indicates that the sample is better able to return to its original position (like a rubber band).
The present invention has been described both in general and in detail by way of examples. These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.
The present application claims priority to U.S. Provisional Application Ser. No. 62/368,414, filed on Jul. 29, 2016, which is incorporated herein in its entirety by reference thereto.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/030741 | 5/3/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62368414 | Jul 2016 | US |
