Related Applications

[0001] This application claims priority to United States Provisional Application No. 63/192,457, filed May 24, 2021 , and titled INFECTION CONTROL OR PROTECTIVE CLOTHING ARTICLES, which is incorporated herein by reference in its entirety.

Copyright Notice

[0002] © 2022 Amtek Research International LLC. A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 37 CFR § 1 .71 (d).

Technical Field

[0003] Infection control or protective clothing articles, such as gowns, to be worn by healthcare workers in a medical environment, for example a hospital or assisted living facility are disclosed. The articles are formed of a hydrophobic, breathable, polyolefin-based web with a controlled pore size less than or about equal to the size of most bacterial or viral particles. Methods of manufacturing the articles are also disclosed.

Background Information

[0004] In the environment of a hospital or assisted living facility, it has become a common practice to supply a healthcare worker with protective clothing, including a gown, which can be quickly put on or removed to facilitate medical examinations and other required procedures. The protective clothing is also designed to protect the healthcare worker from bodily fluids and other contaminants. [0005] In many facilities, reusable protective clothing is available which are fabricated of woven natural or synthetic materials such as cotton or polyester. Such gowns must be laundered and resterilized after each wearing, thereby adding to operating costs. As an alternative, non-woven materials can also be used to manufacture protective gowns that are disposable, but both the fiber diameter and pore size are relatively large providing less protection than desired.

[0006] While gowns can be made from a variety of polymers including polyvinyl chloride, these materials are usually non-porous. While the polymer material can be perforated to supply some level of breathability, the pore size is macroscopic and cannot protect the health care worker from microscopic organisms such as bacterial and viral particles.

[0007] Expanded polytetrafluoroethylene (ePTFE) membranes have been used in a wide variety of applications were porosity is required, but they are inherently costly and suffer from deficiencies in ease of handling and recyclability. In many cases, ePTFE membranes are coated with a polyurethane to penetrate the pores and form a non-porous polyurethane (PU) layer as described in US Patent No. 4,194,041. The purpose of the PU layer is to provide resistance to water and other contaminants primarily because of the lack of porosity, i.e., there is no open pathway for contaminants or air to pass through the membrane. [0008] In order to better protect the health care worker while maintaining a level of comfort and ease of removal, it is desirable for the disposable infection control gown to be made from a microporous membrane having a controlled pore size.

Summary of the Disclosure

[0009] The present disclosure describes a strong, light weight, waterproof, microporous polymer web that can be used to manufacture a disposable article of personal protective equipment (PPE). The polymer web contains a polyolefin such as low density (LDPE), medium density (MDPE), linear low density (LLDPE), high density (HDPE), ultrahigh molecular weight (UHMWPE) polyethylene, polypropylene (PP), polymethyl pentene (TPX), or a mixture thereof. The free-standing, polyolefin- based web has 30-70 % porosity with a median pore size less than 0.25 urn. The hydrophobic nature of the web helps it to repel body fluids, the high porosity promotes excellent breathability, while the controlled pore size excludes most bacteria and viruses. The disclosure also describes methods for sealing and cutting the polymer web to form gowns with easy-on and easy-off characteristics.

[0010] Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. Brief Description of the Drawings

[0011] The embodiments disclosed herein will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. These drawings depict only typical embodiments, which will be described with additional specificity and detail through use of the accompanying drawings in which:

[0012] FIGS. 1 A and 1 B depict a gown according to an embodiment of the present disclosure.

[0013] FIG. 2 depicts a portion of a back side of the gown of FIGS. 1A and 1 B, illustrating a tearaway seam.

[0014] FIG. 3 depicts the back side of the gown of FIGS. 1A and 1 B as worn by a user, illustrating the tear-away seam of FIG. 2.

[0015] FIG. 4 depicts an end portion of a sleeve of the gown of FIGS. 1A and 1 B, including a thumb hole.

[0016] FIGS. 5A and 5B depict a gown according to another embodiment of the present disclosure.

[0017] FIG. 6 depicts a scanning electron microscopy image of the pore structure morphology of a polyolefin-based web prepared in accordance with the present disclosure.

[0018] FIG. 7 depicts the log differential intrusion vs. pore size of a polyolefin-based web prepared in accordance with the present disclosure.

[0019] FIG. 8 depicts an optical micrograph of a commercially available blue polyethylene (PE) gown material.

[0020] FIG. 9 depicts an optical micrograph of a commercially available yellow polypropylene (PP) gown material.

[0021] FIG. 10 depicts a web sample prepared in accordance with ASTM D-1004 90° tear test.

[0022] FIG. 11 depicts a test set up used in accordance with examples of the present disclosure. Detailed Description

[0023] Disclosed herein are disposable, protective articles formed from a free-standing, hydrophobic, breathable, polyolefin-based web with a median pore size less than or equal to 0.25 urn (e.g., such as from 0.05 urn to 0.75 urn, from 0.075 urn to 0.5 urn, or from 0.1 urn to 0.3 urn). The disposable, protective articles preferably have a porosity of 30% to 70%. The disposable, protective article preferably has a tortuosity greater than 1.2 (e.g., such as 1.25, 1.3, 1.4, or 1.5). That level of tortuosity cannot be achieved by simply perforating a membrane with straight holes, which would result in a tortuosity close to 1 . The pores of the disposable, protective article are not straight through. Thus, even if a bacterial or viral particle is small enough to enter a pore, the bacterial or viral particle may be trapped in the pores due to the tortuous nature of the porosity.

[0024] The article can have two-layers of the polyolefin-based web joined at the edges of the article. In forming the article, the first and second layers may be joined together at various locations, including at the edges. Heat sealing, RF welding, ultra-sonic welding, adhesives, tapes, sewing, or other processes or mechanisms suitable for joining thermoplastic materials together may be used to join the edges of the layers together. The joining process preferably defines seams along portions of the article. Suitable processes may also be used to alter the structure of the sheets at other areas of first and second sheets. Such processing may soften edges, adjust tear-resistance, add stiffness or otherwise enhance the functionality of the article.

[0025] Preferably, an individual layer of the polyolefin-based web has a thickness of 9 microns to 30 microns and is lightweight.

[0026] The polyolefin-based web can be made through a variety of processes and with a variety of polyolefins. Example 1 below provides one example of a “wet process” for forming polyolefin- based webs with polyethylene and a plasticizer. Likewise, a “dry process” utilizing biaxial stretching and polypropylene can also be used. The polymer mixture, formulation, and/or process conditions (such as stretch rates and orientation) can be modified to adjust the thickness and porosity of the webs.

[0027] The polyolefins can include polyethylene (PE) (e.g., low density (LDPE), medium density (MDPE), linear low density (LLDPE), high density (HDPE), ultrahigh molecular weight (UHMWPE) polyethylene, or mixtures thereof), polypropylene (PP), polymethyl pentene (TPX), or a mixture thereof.

[0028] In some embodiments the polyolefin-based web is not laminated with any other material, except as may occur during joining to itself or another layer of the polyolefin-based web along an edge (e.g., lateral edge). The polyolefin-based web provides a freestanding characteristic to the disposable articles. “Freestanding” refers to a web having sufficient mechanical properties that permit manipulation such as winding and unwinding in web form for use in article cut out and assembly. The “freestanding” characteristic allows the articles to be made exclusively (except for perhaps adhesives, tapes, threads, etc. used during assembly of the article) from the polyolefin-based web. Accordingly, disposable articles can be made entirely from the polyolefin-based web (as either a single layer or plurality of layers (e.g., two layers)). Therefore, the disposable, protective articles can also be low cost. [0029] The article is preferably a gown but may be any type of a clothing article such as a shirt, pants, hat, glove, etc. The article may be a portion of a clothing article such as sleeves or leggings for example. The article may be a clothing accessory such as a shoe cover, apron, or a bib, for example. [0030] For the gown embodiment, the gown can include a heat-sealed seam on the back that forms a tear-away seam. The gown can include two sleeves and a thumb hole in each sleeve. For example, polyolefin-based web can be folded back on itself and joined at common edges. The gown can also include two integral ties, one on each side of the gown, configured for tying together and securing the back of the gown during use. The gown preferably has an outer surface and an inner surface composed of only the polyolefin-based web.

[0031] Methods of making disposable, protective gowns are also disclosed herein. The methods include extruding a polyolefin-based web, processing and stretching the polyolefin-based web to impart a median pore size of 0.25 micron or less (e.g., such as from 0.05 micron to 0.75 micron, from 0.075 micron to 0.5 micron, or from 0.1 micron to 0.3 micron); and cutting a gown shape out of a sheet of the polyolefin-based web. The methods can include extruding two layers of the polyolefin-based web and heat sealing the two layers together to define at least some of the edges of the gown. The methods can include folding a portion of the polyolefin-based web back on itself and joining common edges to form a sleeve of the gown.

[0032] FIGS. 1 A and 1 B depict an example gown 100 according to an embodiment of the present disclosure. FIG. 1A depicts a rear view of the gown 100, and FIG. 1 B depicts a front view of the gown. The gown 100 is shaped or otherwise configured to cover the front side and the back side of a wearer from the neck to below the knees. The gown 100 can include long sleeves 106 to cover the arms of the wearer from the shoulder to beyond the wrist. The sleeve 106 can also cover a portion of the hand and include a thumb hole 108 as described below. The gown 100 includes a neck opening 101 through which the head of the wearer may pass through when donning gown 100. In some embodiments, the first layer of the polyolefin-based web forms the outer surface of the gown 100 and the second layer forms the inner surface. The gown 100 can include slits, openings or other features to facilitate handling, donning, wearing, and removal of the gown 100. The gown 100 can include a back side slit 104 extending along a length of the gown 100. The back side slit 104 may facilitate donning and/or removal of the gown 100. After donning, the edges of the back side slit 104 may be tied together (either with integral ties or a separate tie) at one or more locations along the back side slit 104.

[0033] The gown 100 can optionally include other components attached to the polyolefin-based web to enhance functionality of the gown 100. Such other components may enhance elasticity, flexibility, stiffening, weight, shape, and/or other functional aspects of the gown 100.

[0034] As depicted in FIG. 1A, the back side slit 104 can optionally extend only partially along the length of the gown 100 (e.g., the back side slit 104 begins a location spaced downward from a neck opening of the gown 100 and continues downward to a bottom end of the gown 100).

[0035] The back side seam 102 of the gown 100 may comprise a tear-away seam 103, as illustrated in FIG. 1A and FIG. 2. The tear-away back side seam 103 may have a tear resistant strength sufficient to maintain closure of the back side seam 102 during donning and wearing of the gown 100. The tear-away seam 103 may have an area of lower tear resistant strength relative to other portions of the gown 100. The tear-away seam 103 may be formed from a heat seal. The area of lower tear resistant strength may be disposed along a line extending the length of the back side seam 102, such as a perforation line for example. The tear-away back side seam 103 may facilitate ease of removal of the gown 100. One or more additional seams may be tear-away seams or have tear-away portions.

[0036] FIG. 3 depicts the back side of the gown from FIGS. 1A and 1 B as worn by the wearer, illustrating placement of the tear-away back side seam 103 and the back side slit 104 extending downward. Sleeves 106 and thumb holes 108 are also depicted as being worn by the user..

[0037] FIG. 4 shows an end portion of a sleeve 106 of the gown of FIGS. 1A and 1 B, including a thumb hole 108. In some instances, extended infection control coverage of a person may be desired. As such, gloves may be a portion of the personal protective equipment worn by a person. In such instances, it may be desirable to extend the gloves over the sleeve portions 106 of the gown to establish an infection barrier between the glove and the sleeve 106. As such, the gown can include a thumb hole 108 adjacent the end of the sleeve 106 to hold the sleeve 106 adjacent the hand when the glove is extended over the sleeve 106.

[0038] FIGS. 5A and 5B illustrate another example of a gown 200 in the form of a partial gown having an open back side produced from a single sheet of polyolefin-based web (as opposed to two layers as with the previous example), or a single sheet of a multilayer composite. The gown 200 resembles the previous gown in some respects. Relevant disclosure set forth above regarding similarly identified features and/or components thus may not be repeated hereafter. Moreover, specific features of the second gown may not be specifically discussed in the written description that follows. However, such features and/or components may clearly be the same, or substantially the same, as features depicted in other embodiments and/or described with respect to such gowns. Accordingly, the relevant descriptions of such features and/or components apply equally to the features of the second gown. Any suitable combination of the features, and variations of the same, described with respect to the first gown and related components can be employed with the second example gown.

[0039] FIG. 5A shows a single sheet of the polyolefin-based web cut along an outline according to a two-dimensional pattern of the gown 200 as viewed from the back. The gown 200 is shaped and otherwise configured to cover the front side, shoulders, and arms of the wearer. As shown, the gown 200 has a front cover portion 212. The gown 200 includes strips of the web material 214 extending lateral to the front cover portion 212 which may be used as ties to secure the gown 200 to the wearer by extending around the torso of the wearer and being tied together (or tied at the back). The gown 200 includes an upper portion 216 configured to cover the shoulders and arms of the wearer. The upper portion includes a front section to cover the front shoulder area of the wearer and a rear section to cover the rear shoulder area of the wearer. A neck opening 211 is disposed between the front and rear sections. FIG. 5A also shows sleeve sections 218 to be folded and formed into sleeves. Thumb holes 208 are also depicted. [0040] FIG. 5B shows the rear section folded over the front section to form sleeves 206 of the gown. The edges of the front and rear sections are joined together at a seam 205 to finish forming the sleeves 206, such as with heat, tape, or an adhesive. Thumb holes 208 are also depicted.

[0041] While the free-standing, polyolefin-based web with 35-70% porosity and a median pore size less than 0.25 urn can be used itself to form an infection control gown or other protective article, the web can also be combined with another layer, such as a non-woven layer or similar material. The polyolefin web and non-woven layer can be joined at selected points to form a multilayer composite using an adhesive, heat, pressure, ultrasonics or other bonding methods such that the article properties can be enhanced without negatively impacting breathability or the median pore size of the polyolefin layer.

[0042] The type of non-woven material used is not particularly limited, so long as the overall porosity and median pore size is not significantly reduced. By way of non-limiting example, the non- woven material can contain polyethylene terephthalate, polypropylene, cellulose, glass, or combinations thereof.

[0043] In some cases, the article will exhibit different haptics or acoustic characteristics. In other cases, the multilayer structure will improve mechanical properties such as tear resistance.

[0044] The composite articles can be formed by joining the non-woven material to the polyolefin- based web to form a multilayer structure and then cutting or otherwise manipulating the multilayer structure to form the article. Alternatively, the individual layers can be partially or completely cut or otherwise manipulated into the shape of the article prior to the layers being joined together. In some embodiments, the non-woven material can be spunbond directly onto the polyolefin-based web in a roll-to-roll continuous process prior to formation of the article.

Examples

[0045] The following examples are meant to be exemplary and not exhaustive in any way.

[0046] Example 1

[0047] A 140 kg of a naphthenic process oil was dispensed into a Ross mixer where it was stirred and degassed. Next, the following were added and mixed with the oil:

64 kg UHMWPE (Molecular weight ~ 5 million g/mol)

32 kg VHMWPE (Molecular weight ~ 1 million g/mol)

32 kg HMW-HDPE ( Molecular weight ~ 0.6 million g/mol)

1 .2 kg Stearate lubricant 1 .2 kg Hindered phenol antioxidant

The mixture was blended at ~ 40 C until a uniform 47 w/w % polymer slurry was formed. The polymer slurry was then pumped into a 103 mm diameter, co-rotating twin screw extruder, while a melt temperature of ~ 215 C was maintained. The extrudate passed through a melt pump that fed a 257 mm diameter annular die having a 2.75 mm gap. The throughput through the die was 230 kg/hr, and the extrudate was inflated with air to produce a biaxially oriented, oil-filled film with a ~ 2000 mm diameter, which then passed through an upper nip at 20 m/min to collapse the bubble and form a double layer. [0048] The collapsed double layer web was slit open on both edges and then conveyed through an extractor tank filled with trichloroethylene to remove the process oil. Next, the extracted web was sequentially stretched in the machine direction (1.5 x) and transverse direction (2.18 x) at 128 C. The rails were narrowed at the end of the transverse direction orientation (TDO) equipment and the sheet was relaxed ~ 18%. The individual webs were briefly separated over a series of rollers, but then recombined and wound as a 1 .5 meter wide, double layer onto a cardboard core at 31.8 m/min. The porosity of the individual sheets was calculated to be 45%.

[0049] Example 2

[0050] Scanning electron microscopy was used to examine the pore structure and morphology of the polyolefin-based web from Example 1. It revealed interconnected polymer fibrils with spherical and/or elliptical pores distributed throughout. FIG. 6 depicts the scanning electron microscopy image. [0051] Example 3

[0052] Hg porosimetry (Micromeritics ASAP 2000) was used to evaluate the pore size distribution of the polyolefin-based web from Example 1 and gave a median pore size of ~ 0.16 um. The pore size distribution for the Example 1 material is displayed below. A graph depicting the log differential intrusion vs. pore size is depicted in FIG. 7.

[0053] Example 4

[0054] Key properties for the polyolefin-based web from Example 1 are shown below and compared with some commercial infection control gown material.

[0055] Optical micrographs of the Blue polyethylene (PE) gown material (FIG. 8) reveal a diamond pattern, but no porosity as also evidenced by the material being too dense to test, indicating there is no porosity for air flow. In contrast, optical micrographs of the yellow polypropylene (PP) non-woven material (FIG. 9) reveal large fibers and pores which result in a zero air permeability value, indicating that the structure results in no resistance to air flow.

[0056] Example 5

[0057] A 2-meter long sample of the double layer, polyolefin-based web from Example 1 was pulled from the roll and placed on a clean table. A cardboard cut-out representing the outline of a medical gown was placed on the sample. A 10 mm wide, heat sealer was then used to trace the perimeter of the cardboard cutout except for the edge which would be the bottom portion of the gown. A length of clear packaging tape was placed on the sample at the bottom edge and cut to a length which would be in the middle of the shoulder blades. A vertical slit was then made along the packaging tape at what would become the back of the infection control gown. Next, the web was cut with scissors to form a neck hole and a vertical heat seal was applied from the top of the gown to the top of the slit in the packaging tape to form a back side seam.

[0058] The sleeves were then opened at the end, and a 50 mm x 50 mm piece of packaging tape was applied to one surface and a circular, thumb hole was then punched. This feature allows gloves to easily be worn and mate to the gown for better protection.

[0059] Example 6

[0060] A single layer of 1.5 meter x 2.0 meter polyolefin-based sheet from Example 1 was placed on a clean table. A cardboard cut-out of a medical gown was placed on the sample which was then cut into the gown precursor as shown in FIG. 5A. In this design, the sleeve was created by folding and then sealing the edge with either heat sealing or double-sided tape, as shown in FIG. 5B.

[0061] Example 7

[0062] A polyester spunbond (20 g/m ² ; Johns Manville) was lightly sprayed with an adhesive (Spraymount; 3M) and then combined with a 20 urn thick UHMWPE-based web as manufactured in Example 1. As shown in the Table below, the Gurley value for the multilayer composite was only slightly higher and within the variation expected for the UHMWPE-based web itself. This result indicates that multilayer composite retains good air permeability for comfort.

[0063] A benefit to the multilayer composite is observed in a Notch test to measure tear resistance, or the load required to initiate a tear in either the machine direction (MD) or transverse direction (TD) relative to the UHMWPE-based web. The Notch test was performed using an Instron. Samples were cut into the shape specified by the ASTM D-1004 90° tear, or Graves’ tear, test (FIG. 10). Fig. 11 depicts the Instron set up. Tests were run at 25 mm gauge length and 254 mm/min speed. [0064] The presence of the spunbond in the multilayer composite increased the load required to initiate a tear greater than two-fold in either direction relative to the UHMWPE-based web alone.

[0065] Example 8

[0066] A polyester spunbond (20 g/m ² ; Johns Manville) was lightly sprayed with an adhesive (Spraymount; 3M) and then combined with a 5 urn thick UHMWPE-based web (ENTEK Membranes LLC). As shown in Table below, the Gurley value for the multilayer composite was slightly lower and within the variation expected for the UHMWPE-based web itself. This result indicates that multilayer composite retains good air permeability for comfort.

[0067] A benefit to the multilayer composite is observed in a Notch test to measure tear resistance, or the load required to initiate a tear in either the machine direction (MD) or transverse direction (TD) relative to the UHMWPE-based web. The presence of the spunbond in the multilayer composite increased the load required to initiate a tear greater than 6 times in either direction relative to the UHMWPE-based web alone. The tests were performed in the same manners as the Notch tests in Example 7.

[0068]

[0069] Changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.