Patent Application
20240215666
© 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).
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.
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.
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.
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.
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 U.S. Pat. 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.
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.
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 um. 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.
Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.
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:
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 um (e.g., such as from 0.05 um to 0.75 um, from 0.075 um to 0.5 um, or from 0.1 um to 0.3 um). 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.
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.
Preferably, an individual layer of the polyolefin-based web has a thickness of 9 microns to 30 microns and is lightweight.
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.
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.
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.
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.
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.
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.
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.
As depicted in
The back side seam 102 of the gown 100 may comprise a tear-away seam 103, as illustrated in
While the free-standing, polyolefin-based web with 35-70% porosity and a median pore size less than 0.25 um 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.
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.
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.
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.
The following examples are meant to be exemplary and not exhaustive in any way.
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:
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×) and transverse direction (2.18×) 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%.
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.
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
Key properties for the polyolefin-based web from Example 1 are shown below and compared with some commercial infection control gown material.
Optical micrographs of the Blue polyethylene (PE) gown material (
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.
The sleeves were then opened at the end, and a 50 mm×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.
A single layer of 1.5 meter×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
A polyester spunbond (20 g/m2; Johns Manville) was lightly sprayed with an adhesive (Spraymount; 3M) and then combined with a 20 um 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.
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 (
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.
A polyester spunbond (20 g/m2; Johns Manville) was lightly sprayed with an adhesive (Spraymount; 3M) and then combined with a 5 um 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.
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.
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.
This application claims priority to U.S. 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.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/072540 | 5/24/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63192457 | May 2021 | US |
