Disposable, Compostable Surgical/Medical Masks and Methods of Production Therefor

Abstract

Disclosed are disposable, compostable surgical/medical masks comprising (i) a 3-ply face-mask component wherein the two outer layers are a spunbond PLA textile and the third center layer is a meltblown PLA textile, (ii) a deformable nose bar formed from a PLA extrudate, and (iii) a pair of elongate narrow-width 3-ply stretchable soft ear loop strips wherein the two outer strips are spunbond PLA textile and the third middle layer is a compostable elastic film. Some embodiments relate to 4-ply disposable, compostable surgical/medical masks comprising two outer layers each comprising a spunbond PLA textile and two middle layers comprising meltblown PLA textile. Some embodiments relate to 4-ply disposable, compostable surgical/medical masks comprising two outer layers each comprising a spunbond PLA textile, a middle layer comprising a spunbond PLA textile, and a middle layer comprising a meltblown PLA textile.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

This disclosure generally relates to disposable surgical/medical masks. More specifically, this disclosure pertains to disposable, compostable 3-ply surgical/medical soft masks and to methods, equipment, and systems for producing the masks.

Background

The recent rapid onset and spread of the Covid 19 virus throughout the globe followed by the subsequent emergence and even more rapid spread of Covid variants has resulted in an urgent and increasing high demand for face masks for use by medical service providers and for personal use to shield and protect individuals from air-borne virus particles that are expelled in aerosols and droplets from virus-infected individuals.

As a result, there has been a rapid increase in production and availability of a variety of masks and face shields for protection against contact with and inhalation of airborne virus particles and aerosol-borne virus particles. The Centers for Disease Control and Prevention (“CDC”) has published numerous guidelines and updates regarding types and use of face masks to reduce the risk of infection by airborne viruses. Their recommendations for “medical procedure masks”, also commonly referred to as “surgical masks” or disposable face masks intended for health care provider use and community use are to select masks that are made of multilayered, non-woven materials, have adjustable nose wires, and are provided with ear loops that provide a secure fit or alternatively, can be adjusted to provide a secure fit.

Currently available in large quantities are disposable surgical/medical face masks that generally satisfy the CDC masking guidelines and are generally advertised as satisfying ASTM (American Society for Testing and Materials) Level 1 (low barrier protection) and/or Level 2 (moderate barrier protection) and/or Level 3 (maximum barrier protection) based on their fluid resistance, filtration efficiency, and breathability.

ASTM Level 1 surgical/medical masks are rated as having low fluid resistance (resistance of the mask to penetration of a small volume of fluid at a high velocity) of 80 mmhg, a bacterial filtration efficiency (BFE) of ≥95% and a 0.1-micron particulate filtration efficiency (PFE) of ≥95%, and a breathability differential pressure (delta P) of <4.0 mm H₂O/cm³ (as the DP value increases, the less the breathability or ease of breathing, but the better the filtration).

ASTM Level 2 surgical/medical masks are rated as having moderate fluid resistance of 120 mmhg, a BFE of ≥98% and PFE of ≥98%, and a breathability delta P of <5.0 mm H₂O/cm³.

ASTM Level 3 surgical/medical masks are rated as having high fluid resistance of 160 mmhg, a BFE of ≥98% and PFE of ≥98%, and a breathability delta P of <5.0 mm H₂O/cm³.

Most commercially available disposable ASTM Level 2 and Level 3 surgical/medical masks have 3 or 4 layers (that is 3-ply or 4-ply) of pleated polypropylene and melt-blown polymeric textiles comprising microfibers and nanofibers produced by extruding thermoplastic polymer melts through small nozzles surround by a high-speed blowing gas to thereby form non-woven sheets. Examples of thermoplastic polymers commonly used to produce melt-blown textiles include polypropylene, polystyrene, polyesters, polyurethane, polyamides (nylons), polyethylene, polycarbonate, and the like. Such disposable surgical/medical masks are typically manufactured by drawing out from spools or bobbins along a machine, a three-layered sheet having a middle layer of a selected textile with a top layer and a bottom layer of a selected non-woven textile. The three-layered sheet is pleated then ultrasonically welded, then stamped with a deformable metal nose strip and a pair of elasticized ear loops that are ultrasonically welded to the mask. Some manufacturing processes, prior to ultrasonically welding the three layers together, insert the deformable metal nose strips between two layers along an elongate side edge prior to the ultrasonic welding step.

Problems associated with the currently available disposable medical/surgical masks include many poorly and/or loosely fitting masks that result in gaps around the noses and along the sides of the mask wearers that provide entrance routes for virus-containing respiratory aerosols. Highly resilient elastic materials used for many medical/surgical mask types may cause compressive and pinching strains around wearers' ears when worn for only short periods of time.

Additionally, the heavy usage of disposable surgical/medical masks since the onset of the Covid pandemic has created significant problems with large-volume processing of discarded used masks. The currently available surgical/medical masks are made with materials, that is metal strips, elasticized ear loops, and biodegradable-resistance textiles spun from thermoset polymers, that can only be safely disposed of and eliminated through incineration and then valorization.

BRIEF SUMMARY OF THE INVENTION

The embodiments of the present disclosure generally relate to disposable, compostable surgical/medical masks comprising assemblies of a plurality of components wherein the components have been fashioned from polylactic acid (PLA) materials and polymeric resin materials.

One example embodiment relates to a disposable, compostable surgical/medical mask comprising (i) a 3-ply face-mask component wherein the two outer layers are a spunbond PLA textile and the third center layer is a meltblown PLA textile, (ii) a deformable nose bar formed from a PLA extrudate, and (iii) a pair of elongate narrow-width 3-ply stretchable soft ear loop strips wherein the two outer strips are spunbond PLA textile and the third middle layer is a compostable elastic polymeric resin film. According to an aspect, a pair of resilient elastic ear loops may be substituted for the pair of elongate narrow-width 3-ply stretchable soft ear loop strips.

The 3-ply face-mask component may be produced by concurrently unspooling a first spunbond PLA textile with a meltblown PLA textile and a second spunbond PLA textile to thereby form a 3-ply layered assembly that may then be pleated by pleating rollers and ultrasonically welded to form a laminated 3-ply face-mask component.

Another example embodiment relates to a disposable, compostable surgical/medical mask comprising (i) a 4-ply face-mask component wherein the two outer layers are a spunbond PLA textile and the two middle layers are a meltblown PLA textile, (ii) a deformable nose bar formed from a PLA extrudate, and (iii) a pair of elongate narrow-width 3-ply stretchable soft ear loop strips wherein the two outer strips are spunbond PLA textile and the third middle layer is a compostable elastic polymeric resin film. According to an aspect, a pair of resilient elastic ear loops may be substituted for the pair of elongate narrow-width 3-ply stretchable soft ear loop strips. According to an aspect, a pair of resilient elastic ear loops may be substituted for the pair of elongate narrow-width 3-ply stretchable soft ear loop strips.

The 3-ply face-mask component may be produced by concurrently unspooling a first spunbond PLA textile with two meltblown PLA textiles and a second spunbond PLA textile to thereby form a 4-ply layered assembly that may then be pleated by pleating rollers and ultrasonically welded to form a laminated 4-ply face-mask component.

The deformable nose bar may be produced by extrusion of an extrusion-grade PLA through an extruder fitted with a die with round bores therethrough to produce elongate solid round PLA bars or alternatively, through a die having elongate slits therethrough to produce solid rectangular PLA strips. According to an aspect, the solid round PLA bars may be corrugated. According to another aspect, the solid rectangular bars may be corrugated. According to another aspect, the deformable nose bar may be an aluminum strip.

The 3-ply soft ear loop strips may be produced by concurrently unspooling a first spunbond PLA textile with a first compostable elastic film and a second spunbond PLA textile to thereby form a 3-ply layered assembly that may then be bonded together by ultrasonic welding to produce an intermediate laminate textile. According to an aspect, the first and second PLA textiles may be meltblown PLA textiles. According to another aspect, the 3-ply layered assembly may be bonded together by passage through a hot-roll calendaring apparatus. According to another aspect, the 3-ply layered assembly may be bonded together by an adhesive bonding process. The intermediate textile may then be activated by passage through one or more stages of rollers having circumferential grooves of generally rectangular or triangular form that closely mesh to thereby stretch the two outer inelastic layers and cause a permanent elongation in the laminated textile in the cross direction (CD) that does not exceed the elastic limit of the elastic film sandwiched between the two outer layers. This elongation activates 3-ply laminated textile and provides soft resilience that enables the textile to be stretched and then return to its original shape in the cross direction (CD) while maintaining stiffness in the machine direction (MD). The activated 3-ply stretchable textile may then be cut into elongate strips having a selected width, along the machine-direction axis of the activated 3-ply stretchable textile to thereby form 3-ply stretchable soft ear loop strips. According to some aspects of the present disclosure, the disposable, compostable soft ear loop strips may comprise two layers of textile wherein one layer may be a spunbond PLA textile and the second layer may be a compostable elastic polymeric resin film. According to some other aspects, the disposable, compostable soft ear loop strips may comprise four or more layers of heat-embossed textiles wherein are alternating layers of spunbond PLA textiles and compostable elastic polymeric resin films.

According to another embodiment, the disposable, compostable 3-ply surgical/medical masks disclosed herein may be assembled by ultrasonic welding the deformable PLA nose bar along one of the elongate edges of the laminated 3-ply face-mask component, then ultrasonically welding of the ends of a first. 3-ply stretchable soft ear loop strip about the top and bottom of one side edge of the laminated 3-ply face-mask component, and then ultrasonically welding of the ends of a second. 3-ply stretchable soft ear loop strip about the top and bottom of the opposite side edge of the laminated 3-ply face-mask component to thereby produce a disposable, compostable surgical/medical mask according to this disclosure. Alternatively, each of a pair of resilient elastic ear loops may be electronically welded to the top and bottom edges of the laminated 3-ply face-mask component.

According to another embodiment, the disposable, compostable 4-ply surgical/medical masks disclosed herein may be assembled by ultrasonic welding the deformable PLA nose bar along one of the elongate edges of the laminated 4-ply face-mask component, then ultrasonically welding of the ends of a first. 3-ply stretchable soft ear loop strip about the top and bottom of one side edge of the laminated 3-ply face-mask component, and then ultrasonically welding of the ends of a second. 3-ply stretchable soft ear loop strip about the top and bottom of the opposite side edge of the laminated 4-ply face-mask component to thereby produce a disposable, compostable surgical/medical mask according to this disclosure. Alternatively, each of a pair of resilient elastic ear loops may be electronically welded to the top and bottom edges of the laminated 4-ply face-mask component.

According to some aspects of the present disclosure, the disposable, compostable surgical/medical masks may comprise five layers of compostable textile layers in which case, the masks may be referred to as 5-ply disposable, compostable surgical/medical masks. According to some other aspects, the intermediate layer or layers may comprise an electrospun PLA layer or layers.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

FIGS. 1A-1B show perspective exploded views of a disposable, compostable 3-ply mask according to an embodiment disclosed herein wherein FIG. 1A is a front view of the three layers before pleating, and FIG. 1B is a front view of the three layers after pleating;

FIG. 2A is an outward-facing front view of an example embodiment of a disposable, compostable 3-ply mask disclosed herein;

FIG. 2B is an inward-facing back view of the mask shown in FIG. 2A;

FIG. 3A is a close-up front view of a side edge of the mask shown in FIG. 2B, showing a soft resilient ear loop component prior to use of the mask;

FIG. 3B is a close-up front view of the side edge after the ear loop component has been separated from the mask and activated for securing the mask to the individual's face;

FIG. 4A is an inside back view of the mask shown in FIG. 2A, unfolded with the ear loops separated and deployed for mounting onto an individual's face;

FIG. 4B is a front view of the unfolded mask shown in FIG. 4A;

FIG. 5 is a close-up front view of the side edge of the unfolded mask shown in FIG. 4B after the ear loop component has been separated from the mask;

FIGS. 6A-6B show perspective exploded views of the disposable, compostable 3-ply mask shown in FIG. 1, wherein FIG. 6A is a front view of the 3-ply mask provided with an elastic ear loop component, and FIG. 6B is a front view of the 3-ply mask provided with a soft resilient ear loop component;

FIGS. 7A-7B show perspective exploded views of a disposable, compostable 4-ply mask according to an embodiment disclosed herein wherein FIG. 7A is a front view of the four layers before pleating, and FIG. 7B is a front view of the four layers after pleating;

FIGS. 8A-8B show perspective exploded views of the disposable, compostable 4-ply mask shown in FIG. 7, wherein FIG. 8A is a front view of the 4-ply mask provided with an elastic ear loop component, and FIG. 8B is a front view of the 4-ply mask provided with a soft resilient ear loop component;

FIGS. 9A-9D provide an outward-facing front view (FIG. 9A) and an inward-facing rear view (FIG. 9B) of the 4-ply mask provided with an elastic ear loop component shown in FIG. 8A, while FIG. 9C is an outward-facing front view and FIG. 9D is an inward-facing rear view of the 4-ply mask provided with a soft resilient ear loop component shown in FIG. 8B;

FIGS. 10A-10B show a scanning electron microscope image of a meltblown textile according to an embodiment disclosed herein taken at a magnification of 250× (FIG. 10A) and at a magnification of 1000× (FIG. 10B);

FIG. 11 is a chart illustrating the pore distribution and polymer fiber diameter properties of an example single meltblown textile disclosed herein;

FIG. 12 is a chart illustrating the pore distribution and polymer fiber diameter properties of an example double meltblown textile disclosed herein;

FIG. 13 is chart illustrating blood penetration correlation plots for an example single meltblown textile and an example double meltblown textile disclosed herein;

FIG. 14 is a chart illustrating multivariable correlation plots of the GSM and blood penetration performance characteristics of an example single meltblown textile;

FIG. 15 is a chart illustrating multivariable correlation plots of the GSM and blood penetration performance characteristics of an example double meltblown textile; and

FIGS. 16A-16D show images taken after performance of a sessile drop test with artificial blood on meltblown textiles produced with four difference corona charge processes (FIGS. 16A, 16B, 16C, 16D).

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present disclosure generally relate to disposable, compostable surgical/medical masks comprising assemblies of a plurality of components wherein each of the components has been fashioned from polylactic acid (PLA) materials.

An embodiment of an example of a disposable, compostable 3-ply surgical/medical mask 10 disclosed herein is shown in FIGS. 1 to 6. The disposable, compostable surgical/medical mask 10 has an inward-facing outer layer 20 made from a spunbond PLA textile, an outward-facing outer layer 40 made from a spunbond PLA textile, a middle layer 30 made from a meltblown PLA textile sandwiched between the outward-facing and inward-facing layers 40, 20, and a deformable nosebar 35 formed from extruded PLA. The compostable, disposable surgical/medical mask 10 may be referred to as a 3-ply compostable, disposable surgical/medical mask. It is to be noted that the outward-facing and inward-facing spunbound textile layers 40, 20 may be considered to be and may be referred to as barrier layers. It is also to be noted that the middle meltblown PLA textile layer 30 may be considered to be and may be referred to as a filtration layer.

The deformable nose bar 35 may be produced by extrusion of an extrusion-grade PLA through an extruder fitted with a die with round bores therethrough to produce elongate solid round PLA bars or alternatively, through a die having elongate slits therethrough to produce solid rectangular PLA strips. According to an aspect, elongate solid round PLA bars may be corrugated around their linear axis. According to an aspect, elongate solid rectangular PLA bars may be corrugated around their linear axis. According to another aspect, the deformable nose bar may be a deformable aluminum strip.

The disposable, compostable surgical/medical mask 10 shown in FIGS. 1 to 6 may be referred to as a 3-ply disposable, compostable surgical/medical mask. The 3-ply surgical/medical mask 10 may be produced with conventional disposable mask production equipment known to those skilled in this art, by concurrently unspooling a first spunbond PLA textile 20 with a meltblown PLA textile 30 and a second spunbond PLA textile 40 onto a conveyer belt to thereby form a 3-ply layered assembly that then passes through a set of pleating rollers to thereby form a flat pleated 3-ply assembly. An extruded deformable PLA nosebar 35 material from a continuous roll is then inserted between the first spunbond PLA textile 20 with the meltblown PLA textile 30 near what will be upward-facing upper edge of the mask as the pleated 3-ply assembly is conveyed along by the conveyer belt. After the PLA nosebar 35 material has been inserted, the bottom and top longitudinal edges of the first spunbond PLA textile 20 are folded over the layered meltblown PLA textile 30 and the second spunbond PLA textile 40 and are concurrently heat embossed to form a first continuous multiple-welded strip 21 along the top longitudinal edge of the mask and a second continuous multiple-welded strip 22 along the bottom longitudinal edge of the mask (FIGS. 2A, 2B, 3A, 3B, 5). Suitable heat-embossing processes include ultrasonically welding, hot roll calendaring, adhesive bonding, and the like. According to an aspect, the middle layer sandwiched between the two outer layers may be produced integrally or alternatively, bonded together for assembly into a 3-ply disposable, compostable surgical/medical mask.

In the example embodiment shown in FIGS. 2-5 and 6B, the nosebar 35 is secured in place between top row and the second row of the multiple-welded strip 21. It is optional if so desired, to insert the extruded deformable nosebar material between the melt-blown PLA textile 30 and the outward-facing second spunbond PLA textile 40 prior to the heat embossing step, for example, by ultrasonic welding. It is optional if so desired, to have the extruded deformable nosebar material positioned between the top two welded strips of the plurality welded strips at the top edge of the mask.

The next step after the upper and lower edges of the flat pleated 3-ply assembly comprising the inward-facing spunbond PLA textile layer 20, the middle meltblown PLA textile layer 30, the outward-facing meltblown PLA textile layer 40 and ultrasonically welded to form the welded top strip 21 and the welded bottom strip 22, the side edges 23a, 23b of the mask 10m wherein the mask 10 has upper corners 24a, 24b, and bottom corners 25a, 25b.

The 3-ply disposable, compostable soft ear loop strips 50 may be produced by concurrently unspooling a first spunbond PLA textile with a compostable elastic polymeric resin film and a second spunbond PLA textile to thereby form a 3-ply layered assembly comprising the compostable elastic film sandwiched between the first and second spunbond PLA textile layers. The 3-ply layered assembly may then be bonded together by a heat embossing process to produce a continuous intermediate 3-ply laminate textile. The continuous intermediate textile may then be activated by conveyance through one or more stages of rollers having circumferential grooves of generally rectangular or triangular form that closely mesh together to thereby stretch the two outer inelastic layers and cause a permanent elongation in the 3-ply laminate textile in the cross direction (CD) that does not exceed the elastic limit of the elastic film layer sandwiched between the two outer spunbond PLA textile layers. The elongation of two outer spunbond PLA textile layers caused by conveyance through the rollers activates the 3-ply laminated textile and to thereby provide a soft resilience that enables the textile to be stretched and then return to its original shape in the cross direction (CD) while maintaining stiffness in the machine direction (MD). The activated 3-ply stretchable textile may then be cut into elongate strips along the cross-direction axis of the activated 3-ply stretchable textile to thereby form 3-ply stretchable soft ear loop strips 50.

The disposable, compostable surgical/medical masks 10 may be assembled by ultrasonically welding of the ends of a first 3-ply stretchable soft ear loop strip 50 about the top corner 24a and bottom corner 25a of one side edge 23a of the laminated 3-ply face-mask component, and then ultrasonically welding of the ends of a second. 3-ply stretchable soft ear loop strip 50 about the top corner 24b and bottom corner 25b of the opposite side edge 23b of the laminated 3-ply face-mask component to thereby produce a disposable, compostable surgical/medical mask 10 according to this disclosure. After the mask assembly 20, 30, 40 and the soft resilient ear loops 50 have been completely welded together, the continuous mask assemblies may be separated by cutting bars into individual disposable, compostable pleated surgical/medical masks 10.

According to an aspect, the disposable, compostable, surgical/medical masks 10 may be assembled by ultrasonically welding of the ends of a first 3-ply stretchable soft ear loop strip 50 about the top corners 24a, 24b, and then ultrasonically welding of the ends of a second 3-ply stretchable soft ear loop strip 50 about the bottom corners 25a and bottom corner 25b of the opposite side edge 23b of the laminated 3-ply face-mask component to thereby produce another embodiment of a disposable, compostable surgical/medical mask according to this disclosure.

According to an aspect, a suitable compostable elastic film for use in preparing the soft-resilient ear loops disclosed herein, may be prepared from one of TERRATEK® FLEX FX2200, TERRATEK® FLEX FX1515, TERRATEK® FLEX GDH-B1FA, all available from Green Dot Bioplastics Inc. Emporia, KS, USA (TERRATEK is a trademark owned by Green Dot Bioplastics LLC, Cottonwood Falls, KS, USA), and the like.

According to an aspect, the first and second PLA textiles used to produce a 3-ply stretchable textile suitable to produce stretchable soft ear loop strips may be meltblown PLA textiles. According to another aspect, the 3-ply layered laminate assembly may be bonded together by passage through a hot-roll calendaring apparatus. According to another aspect, 3-ply layered laminate assembly may be bonded together by adhesive bonding.

Alternatively, the 3-ply layered laminate assembly may be provided with a pair of resilient elastic ear loops 45 (FIG. 6A) in place of the 3-ply soft ear loops 50 (FIG. 6B).

An embodiment of an example of a disposable, compostable 4-ply surgical/medical mask 60 disclosed herein is shown in FIGS. 7 to 10. The disposable, compostable surgical/medical mask 60 has an inward-facing outer layer 85 made from a spunbond PLA textile, an outward-facing outer layer 65 made from a spunbond PLA textile, two middle layers 75, 80 made from meltblown PLA textile sandwiched between the outward-facing and inward-facing layers 65, 85, and a deformable nosebar 70 formed from extruded PLA. The compostable, disposable surgical/medical mask 60 may be referred to as a 4-ply compostable, disposable surgical/medical mask.

The 4-ply compostable, disposable surgical/medical mask 60 may be produced with conventional disposable mask production equipment known to those skilled in this art, by concurrently unspooling a first spunbond PLA textile 65 with two meltblown PLA textiles 75, 80 and a second spunbond PLA textile 85 onto a conveyer belt to thereby form a 4-ply layered assembly (FIG. 7A) that then passes through a set of pleating rollers to thereby form a flat pleated 4-ply assembly (FIG. 7B). An extruded deformable PLA nosebar 70 material from a continuous roll is then inserted between the first spunbond PLA textile 75 and the first meltblown PLA textile 75 near what will be upward-facing upper edge of the mask as the pleated 4-ply assembly is conveyed along by the conveyer belt. After the PLA nosebar 70 material has been inserted, the bottom and top longitudinal edges of the first spunbond PLA textile 95 are folded over the layered meltblown PLA textiles 75, 80 and the second spunbond PLA textile 85 and are concurrently heat embossed to form a first continuous multiple-welded strip along the top longitudinal edge of the mask and a second continuous multiple-welded strip along the bottom longitudinal edge of the mask. Suitable heat-embossing processes include ultrasonically welding, hot roll calendaring, adhesive bonding, and the like.

In the example embodiment shown in FIGS. 7-9, the nosebar 35 is secured in place between top edges of the outward-facing spunbond textile and the first meltblown textile layer 75. It is optional if so desired, to insert the extruded deformable nosebar material between the top edges of the two melt-blown PLA textiles 75, 80 prior to the heat embossing step, for example, by ultrasonic welding. It is optional if so desired, to have the extruded deformable nosebar material positioned between top edges of the second meltblown textile layer 80 and the inward-facing spunbond textile 85. It is optional to substitute deformable aluminum nosebars in place of the extruded deformable nosebar materials. It is to be noted that the outward-facing and inward-facing spunbound textile layers 65, 85 may be considered to be and may be referred to as barrier layers. It is also to be noted that the two middle meltblown PLA textile layers 75, 80 may be considered to be and may be referred to as filtration layers.

The next step after the upper and lower edges of the flat pleated 4-ply assembly comprising the inward-facing spunbond PLA textile layer 85, the middle meltblown PLA textile layers 75, 80, the outward-facing meltblown PLA textile layer 65 are laminated with a deformable nosebar 70 placed near the top edges of two selected textile layers, is ultrasonically welding to form the welded top and bottom strips, followed by ultrasonically welding the side edges together, followed ultrasonically welding each of the pair of ear loops 90, 95FIGS. 8A, 8B) to the upper corners and bottom corners of the 4-ply disposable, compostable surgical/medical mask 60.

Another example embodiment relates to lamination of layered textile assemblies to provide 3-ply or 4-ply disposable, compostable face masks according to the present disclosure, that selectively may pass (i) level 1 of the ASTM F2100 Standard Specification for Performance of Materials used in Medical Face Masks for use in environments wherein there is low risk of fluid exposure (no splashes or sprays expected), or alternatively, (ii) level 2 of the ASTM F2100 Standard Specification for use in environments wherein there is moderate risk of fluid exposure (some occurrence of splashes or sprays expected), or alternatively (iii) level 3 of the ASTM F2100 Standard Specification for use in environments wherein there is a high risk of fluid exposure (likely occurrence of splashes or sprays expected).

Examples of suitable layers of spunbond PLA textiles that may pass a selected level of ASTM F2100 Standard Specification include single layers having a GSM value (weight in grams per square metre) from a range of about 20 to about 65, for example about 25 GSM, about 40 GSM, about 50 GSM. Also suitable are double layers of spunbond PLA textiles having a about 20/20 GSM or a about 25/25 GSM or a about 30/30 GSM.

Examples of suitable layers of meltblown PLA textiles that may pass a selected level of ASTM F2100 Standard Specification include single layers having a gsm value (weight in grams per square metre) from a range of about 20 to about 65, for example about 25 GSM, about 40 GSM, about 50 GSM. Also suitable are double layers of meltblown PLA textiles having a about 20/20 GSM or a about 25/25 GSM or a about 30/30 GSM.

It should be noted that doubled-layered meltblown PLA textiles and double-layered spunbond PLA textiles may pass a selected ASTM F2100 level may be thinner than single-layer meltblown and spunbond PLA textiles GSMs required to pass the same ASTM F2100 level. For example, a double-layered spunbond PLA textile with a GSM of about 25/25 may be thinner than a single-layer spunbond PLA textile having a GSM of about 40 or about 50.

Suitable 3-ply disposable, compostable masks configured to pass level 1 or alternative, level 2 or alternatively, level 3 of the ASTM F2100 Standard Specification, may comprise an outward-facing spunbond layer, a meltblown middle layer, and an inward-facing spunbond layer. It was found that this configuration was able to achieve the performance requirements for level 3 ASTM F2100 Standard Specification. The overall construction of the masks can be reduced in weight and therefore, in cost. Additionally, with two layers of meltblown, the barrier properties of one layer can be varied in relation to the other. This allows for a more optimal construction of the mask which results in exceeding the minimum performance requirements of the mask. Suitable 4-ply disposable, compostable masks configured to pass level 1 or alternative, level 2 or alternatively, level 3 of the ASTM F2100 Standard Specification, may comprise an outward-facing spunbond layer, two meltblown middle layers, and an inward-facing spunbond layer or alternatively, an outward-facing spunbond layer, a middle spunbond layer, a meltblown middle layer, and an inward-facing spunbond layer.

Samples of double-layer meltblown PLA textile and double-layer spunbond PLA textile were examined under a high-resolution large-chamber scanning electron microscope (SEM). Samples were prepared by gold sputtering, and then were examined with a JSM-IT700HR In TouchScope™ Field Emission SEM (Jeol USA Inc.). FIG. 10A is a micrograph of a double-layer meltblown PLA textile taken at a 1000× magnification, wherein it is apparent that the diameters of the meltblown fibers were in a range of 1 μm to 10 μm. FIG. 10B is a micrograph of a double-layer spinbond PLA textile taken at a 250× magnification, wherein it is apparent that the diameters of the spunbond fibers were in a range of about 10 μm to about 20 μm.

It should be noted that the performance of the single-layer and double-layer meltblown PLA textiles may be improved by corona charging of the meltblown PLA textiles with forward/reverse charging with negative ions. The corona charging process creates an electrostatic charge on the fibers of the meltblown textile and is used to increase the filtration efficiency of the media while allowing the pressure drop through the media to remain within the ASTM F2100 Standard Specification performance requirements of the mask specification. Corona charging typically takes place in the production environment using ambient air around the manufacturing site. Charging for typical filtration media utilizes negative corona charging ions (typically 30 kV-100 kV DC potential) and is applied to both surfaces of the filter media during production. An example of a suitable final charging process for a meltblown textile may be −30 kV top side, −30 kV bottom side, +60 kV top side. However, those skilled in these arts will know how to vary the process to obtain their desired results.

It should be noted that the hydrophobicity of the spunbond and meltblown PLA textiles may be increased by incorporation of selected additives during production of the textiles to modify the surface charge of the fibers and/or to modify the surface structure of the fibers. Some additives such as metallic soaps may bloom to the surface of the fibers during processing and thereby create a waxy coating that will increase the hydrophobicity of the textile. Other additives may include depositing nanospheres onto the fiber surfaces to thereby modify their surface structures and to increase their hydrophobic properties.

The pore size distributions in a single-layer meltblown PLA textile (FIG. 11) and in a double-layer meltblown PLA textile (FIG. 12) were determined with a capillary flow porometer iPore-1050A (Porous Materials Inc.). The thickness of the single-layer meltblown PLA textile (FIG. 11) was in the range of about 229 μm to about 305 μm with a GSM of about 40. The thickness of the double-layer meltblown PLA textile (FIG. 12) was in the range of about 152 μm to about 229 μm with a GSM of about 25/25. Comparisons of the data in FIGS. 11 and 12 shows that the pore sizes in the double-layer material meltblown PLA textile (FIG. 12) are generally smaller and tighter than in the single-layer meltblown PLA textile (FIG. 11). Accordingly, double-layer material meltblown PLA textile (FIG. 12) may reduce porosity and provide a better barrier to aerosols in comparison to the single-layer meltblown PLA textile (FIG. 11). It was also noted that the thinner double-layer material meltblown PLA textile had a much “softer” tactile feel and would be less expensive to produce than the single-layer meltblown PLA textile.

FIG. 13 shows the particulate filtration efficiencies (PFE) of a 4-ply disposable, compostable mask comprising an outward-facing spunbond layer, a middle spunbond layer, a meltblown middle layer, and an inward-facing spunbond layer (solid line with dark-shaded 95% confidence interval) with a 4-ply disposable, compostable mask comprising an outward-facing spunbond layer, two meltblown middle layers, and an inward-facing spunbond layer (dashed line with light-shaded 95% confidence interval). These data show that the 4-ply disposable, compostable mask comprising an outward-facing spunbond layer, two meltblown middle layers, and an inward-facing spunbond layer performed better (higher PFE performance) than the 4-ply disposable, compostable mask comprising an outward-facing spunbond layer, a middle spunbond layer, a meltblown middle layer. In reference to FIGS. 10A and 10B, it is apparent that the higher PFE-performing 4-ply disposable, compostable mask contained a much higher proportion of small-diameter meltblown fibers about (1 μm to 10 μm) than did the lower PFE-performing 4-ply disposable, compostable mask.

Multivariable correlation analyses were done with 192 4-ply masks configured with an outward-facing spunbond layer, a middle spunbond layer, a meltblown middle layer, and an inward-facing spunbond layer (FIG. 14) and with 480 4-ply masks configured with an outward-facing spunbond layer, two meltblown middle layers, and an inward-facing spunbond layer (FIG. 15). The multivariable analysis (FIG. 14 and FIG. 15) indicated the strongest contributor to blood penetration resistance was Particulate Filtration Efficiency (PFE) which prompted further investigations into the causality of PFE to blood penetration resistance. From a theoretical sense it can be shown that fiber diameter, packing density and thickness can be used to predict PFE (Russel, S. J., 2007, Handbook of Nonwovens. CRC Press). One could theorize fiber diameter, packing density and thickness are also important properties to predict blood penetration resistance which supports the conclusion higher PFE will result in improved fluid jet barrier properties. With this in mind, a PFE measure is used as proxy to blood penetration resistance. This further supports the investigation into capillary flow pore size to blood penetration resistance.

The effects of different methods of corona charging on the hydrophobicity of a single-layer meltblown PLA textile were assessed with the ASTM F1862 Standard Test Method for Resistance of Medical Face Masks to Penetration by Synthetic Blood (Horizontal Projection of Fixed Volume at a Known Velocity) using a sessile drop test to measure the apparent contact angles and are shown in FIG. 16. Samples of single-layer meltblown PLA textile were treated with different corona charging processes as follows:

• • FIG. 16A: No charge: control
  • FIG. 16B: Double N: negative corona charge on both sides of the textile
  • FIG. 16C: Double N+P: negative corona charge on both sides of the textile plus positive charge on one side.
  • FIG. 16D: P only: positive corona charge only

The apparent contact angles determined with the sessile drop test, are measured between the tangent to the liquid-fluid interface and the solid surfaces of the of single-layer meltblown PLA textile treated with different corona charging processes. Assessment of the images FIGS. 16A-16D in FIG. 16 indicated that the best-performing textile was the double N negative corona charge on both sides of the textile plus P positive charge on one side (FIG. 16C). Although the positive corona charge provided an apparent better contact angle (FIG. 16F), the textile receiving this corona charge process did not provide the required PFE performance.

According to some embodiments of the present disclosure, the dimensions of the disposable, compostable, pleated surgical/medical masks at this according to this disclosure, may have a length selected from a range of about 12 cm to about 21 cm and therebetween, and a width selected from a range of about 6 cm to about 13 cm. The disposable, compostable, pleated surgical/medical masks disclosed herein suitable for use by toddlers and young children from the ages of 2 yrs old to 6 yrs old, may have a length selected from a range of about 12 cm to about 14 cm and a width selected from a range of about 6 cm to about 8 cm. The disposable, compostable, pleated surgical/medical masks disclosed herein suitable for use by children and young juveniles from the ages of about 6 yrs old to about 14 yrs old, may have a length selected from a range of about 13 cm to about 16 cm and a width selected from a range of about 7 cm to about 9 cm. The disposable, compostable, pleated surgical/medical masks disclosed herein suitable for use by young adults and adults, may have a length selected from a range of about 15 cm to about 21 cm and a width selected from a range of about 9 cm to about 13 cm. Particularly suitable dimensions for disposable, compostable, pleated surgical/medical masks disclosed herein for adults may have a length of about 17.5 cm and a width of about 10 cm.

A disposable, compostable, pleated surgical/medical mask configured as disclosed herein, may be easily mounted by a user onto their face and secured in place, by simply unfolding the pleats to form a 3-dimensional structure as shown in FIG. 4A, and then separating and activating the soft-resilient ear loop strips 50a from the side edges 23a, 23b as shown in FIG. 4B. The soft-resilient ear loop strips 50a can then be looped around the user's ears. An advantage of the present disposable, compostable, pleated surgical/medical mask with soft-resilient ear loops is that the mask may be worn by a user for an extended period of time without experiencing discomforts associated with prior art disposable surgical/medical masks with elastic ear loops such as pinching and loss of sensory sensation around the ears.

Another advantage of the disposable, compostable, pleated surgical/medical masks disclosed herein, comprising PLA textiles, deformable nosebars, and soft-resilient PLA ear loops is that they can be simply and easily disposed by composting. For example, used disposed compostable masks configured as disclosed herein, may be collected in bulk and then conveyed to a composting site.

The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited.

As used herein “a”, “an”, “said” or “the” means one or more unless otherwise indicated.

Although the invention has been described in detail with particular reference to these embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.

Claims

1. A disposable, compostable pleated surgical/medical mask, comprising: a mask assembly having, (i) an outward-facing first outer layer consisting of a spunbond polylactic acid (PLA) textile,(ii) an inward-facing second outer layer consisting of a spunbond PLA textile,(iii) an intermediate layer(s) consisting of a meltblown PLA textile disposed between the first outer layer and the second outer layer, and(iv) a deformable nosebar disposed between the meltblown PLA layer and one of the first outer layer and the second outer layer about an upper linear edge of the assembly,wherein the mask assembly is pleated with(v) a bottom linear edge of the mask assembly ultrasonically welded together with a first plurality of spaced-apart rows of welds,(vi) the top linear edge of the mask assembly ultrasonically welded together with a second plurality of spaced-apart rows of welds whereby the PLA nosebar is disposed between a pair of the second plurality of spaced-apart rows of welds, and(vii) opposing side edges of the mask assembly ultrasonically welded together with a pair of a third plurality of spaced-apart rows of welds; anda pair of wherein each of the pair of the ear loop strips is formed from a soft-resilient textile wherein the first layer is a spunbond PLA textile, the second layer is a compostable elastic film, and the third layer is a spunbond PLA textile, said soft-resilient textile laminated together by a heat-embossing process, said soft-resilient textile having a stiffness in a machine direction and a resilience in a cross direction;wherein opposing ends of each one of the pair soft-resilient ear loop strips are ultrasonically welded to an upper corner and a bottom corner of the opposing side edges of the mask assembly.

2. The disposable, compostable pleated surgical/medical mask of claim 1, wherein the deformable nosebar is formed from an extruded PLA material.

3. The disposable, compostable pleated surgical/medical mask of claim 1, wherein the deformable nosebar is an aluminum strip.